ELECTROLYTE FOR A SOLID-STATE BATTERY
Electrolyte for a solid-state battery includes a body having grains of inorganic material sintered to one another, where the grains include lithium. The body is thin, has little porosity by volume, and has high ionic conductivity.
This application is a continuation of U.S. application Ser. No. 16/534,573 filed Aug. 7, 2019, which is a continuation of U.S. application Ser. No. 16/295,673 filed Mar. 7, 2019, which issued as U.S. Pat. No. 10,581,115 and is a continuation of International Application No. PCT/US2017/067376 filed Dec. 19, 2017, which claims the priority benefit of U.S. Application Nos. 62/556,712 filed Sep. 11, 2017, 62/526,806 filed Jun. 29, 2017, 62/484,106 filed Apr. 11, 2017, 62/483,726 filed Apr. 10, 2017, 62/470,550 filed Mar. 13, 2017, 62/439,609 filed Dec. 28, 2016, 62/439,598 filed Dec. 28, 2016, 62/439,613 filed Dec. 28, 2016, and 62/437,157 filed Dec. 21, 2016, each of which is incorporated by reference herein in its entirety.
BACKGROUNDThe disclosure relates generally to processes for sintering, such as sintering green tape including polycrystalline ceramic grains or other inorganic particles, bound in a binder, as well as continuous and discrete sintered articles, such as ceramic sheets, tapes or ceramic pieces made from such processes. The disclosure relates articles, such as thin sheets, tapes, ribbons or pieces of ceramic or other inorganic materials that have many potential uses, such as serving as waveguides, when the ceramic is transmissive to light, serving as substrates that may be coated or laminated, and integrated in batteries and other components, or used as or joined with a substrate such as to act as a dielectric in an electronics package (e.g., LED package), or other applications. Various material properties, particularly of ceramic materials, such as high resistivity, low reactivity, low coefficient of thermal expansion, etc. make such articles particularly useful in a wide variety of applications.
SUMMARYSome aspects of the present disclosure relate to a tape separation system for sintering preparation. The tape separation system includes a source of tape material comprising a green tape and a carrier web supporting the green tape. The green tape comprising grains of inorganic material in a binder. The tape separation system further includes a peeler for directing the carrier web in a rewind direction and directing the green tape in a downstream processing direction that differs from the rewind direction, and a vacuum drum positioned and configured to receive the tape material from the source and convey the tape material to the peeler. The vacuum drum comprises holes for applying suction to the carrier web to facilitate tensioning the carrier web, and tension, in force per cross-sectional area, in the carrier web is greater than tension in the green tape as the tape material is conveyed from the vacuum drum to the peeler, thereby mitigating deformation of the green tape during separation of the green tape from the carrier web.
Other aspects of the present disclosure relate to a system for processing tape for sintering preparation. The system includes a tape comprising a green portion of the tape, the green portion having grains of an inorganic material in an organic binder; and a binder burnout station comprising an active heater. The tape advances through the binder burnout station such that the binder burnout station receives the green portion of the tape and chars or burns the organic binder as the green portion of the tape interfaces with heat from the heater, thereby forming a second portion of the tape prepared for sintering the inorganic material of the tape. In some embodiments, at an instant, the tape simultaneously extends to, through, and from the binder burnout station such that, at the instant, the tape includes the green portion continuously connected to the second portion, such as where the binder burnout station chars or burns at least most of the organic binder, in terms of weight, from the green portion of the tape without substantially sintering the grains of the inorganic material. In some embodiments, system for processing tape for sintering preparation further includes an ultra-low tension dancer that includes light-weight, low-inertia rollers to redirect the tape without exerting significant tension such that tension in the second portion of the tape is less than 500 grams-force per mm2 of cross section, thereby reducing chances of fracture of the second portion of the tape and facilitating long continuous lengths of the tape for sintering. In some embodiments, system for processing tape for sintering preparation blows and/or draws gas over the tape as the tape advances through the binder burnout station, and the binder burnout station heats the tape above a temperature at which the organic binder would ignite without the gas blown and/or drawn over the tape, whereby the organic binder chars or burns but the tape does not catch fire.
Additional aspects of the present disclosure relate to a manufacturing line comprising the above system for processing tape, where the binder burnout station is a first station and the manufacturing line further comprises a second station spaced apart from the first station. The second station at least partially sinters the inorganic material of the second portion of the tape to form a third portion of the tape, where, at an instant, the tape includes the green portion continuously connected to the third portion by way of the second portion. For example, in some such embodiments, the third portion of the tape is substantially more bendable than the second portion such that a minimum bend radius without fracture of the third portion is less than half that of the second portion, and the green portion is substantially more bendable than the second portion such that a minimum bend radius without fracture of the green portion is less than half that of the second portion. The manufacturing line may further include the tape separation system described above.
Some aspects of the present disclosure relate to a sintering system comprising a tape material comprising grains of inorganic material and a sintering station. The sintering station includes an entrance, an exit, and a channel extending between the entrance and the exit. At an instant, the tape material extends into the entrance of the sintering station, through the channel, and out of the exit. Heat within the channel sinters the inorganic material such that the inorganic material has a first porosity at the entrance and a second porosity at the exit that is less than the first porosity. Further, the wherein the tape material is positively tensioned as the tape material passes through the channel of the sintering station, thereby mitigating warpage. In some embodiments, the tape material moves through the sintering station at a speed of at least 1 inch per minute. In some embodiments, the channel of the sintering station is heated by at least two independently controlled heating elements, where the heating elements generate a temperature profile where the channel increases in temperature along the length of the channel in a direction from the entrance toward the exit of the sintering station, and where a sintering temperature in the channel exceeds 800° C. In some embodiments, the sintering system further includes a curved surface located along the channel of the sintering station, where the tape material bends relative to a widthwise axis of the tape material around the curved surface as the tape material moves through the sintering station, thereby influencing shape of the tape material. In some embodiments, the exit and the entrance of the sintering station lie in a substantially horizontal plane, such that an angle defined between the exit and the entrance of the sintering station relative to a horizontal plane is less than 10 degrees, thereby at least in part controlling flow of gases relative to the channel; for example, in some such embodiments, the sintering station further comprises an upward facing channel surface defining a lower surface of the channel, and a downward facing channel surface defining an upper surface of the channel, where the downward facing channel surface is positioned close to an upper surface of the tape material such that a gap between the upper surface of the tape material and the downward facing channel surface is less than 0.5 inches, thereby at least in part controlling flow of gases in the channel. The tape material may be particularly wide, long, and thin, having a width greater than 5 millimeters, a length greater than 30 centimeters, and a thickness between 3 micrometers and 1 millimeter, and the inorganic material of the tape may be at least one of a polycrystalline ceramic material and synthetic mineral.
Other aspects of the present disclosure relate to a process for manufacturing ceramic tape, the process comprising a step of sintering tape comprising polycrystalline ceramic to a porosity of the polycrystalline ceramic of less than 20% by volume, by exposing particles of the polycrystalline ceramic to a heat source to induce the sintering between the particles. The tape is particularly thin such that a thickness of the tape is less than 500 μm, thereby facilitating rapid sintering via heat penetration. Further, the tape is at least 5 mm wide and at least 300 cm long. In some embodiments, the process further includes a step of positively lengthwise tensioning the tape during the sintering. In some such embodiments, the process further includes a step of moving the tape toward and then away from the heat source during the sintering. In some embodiments, the amount of time of the sintering is particularly short, that being less than two hours in aggregate, thereby helping to maintain small grain size in the ceramic tape; for example, in some such embodiments, the time in aggregate of the sintering is less than one hour, and density of the polycrystalline ceramic after the sintering is greater than 95% dense by volume and/or the tape comprises closed pores after the sintering. In some embodiments, the tape comprises a volatile constituent that vaporizes during the sintering, where the volatile constituent is inorganic, and where the tape comprises at least 1% by volume more of the volatile constituent prior to the sintering than after the sintering.
Still other aspects of the present disclosure relate to a tape comprising a body comprising grains of inorganic material sintered to one another. The body extending between first and second major surfaces, where the body has a thickness defined as distance between the first and second major surfaces, a width defined as a first dimension of the first major surface orthogonal to the thickness, and a length defined as a second dimension of the first major surface orthogonal to both the thickness and the width. The tape is long, having a length of about 300 cm or greater. The tape is thin, having a thickness in a range from about 3 μm to about 1 mm. The tape is particularly wide, having a width of about 5 mm or greater. According to an exemplary embodiment, geometric consistency of the tape is such that a difference in width of the tape, when measured at locations lengthwise separated by 1 m, is less than 100 μm; and a difference in thickness of the tape, when measured at locations lengthwise separated by 1 m along a widthwise center of the tape, is less than 10 μm. In some embodiments, the tape is flat or flattenable such that a length of 10 cm of the tape pressed between parallel flat surfaces flattens to within 0.05 mm of contact with the parallel flat surfaces without fracturing; and for example in some such embodiments, when flattened to within 0.05 mm of contact with the parallel flat surfaces, the tape exhibits a maximum in plane stress of no more than 1% of the Young's modulus thereof. In some embodiments, the first and second major surfaces of the tape have a granular profile, where the grains are ceramic, and where at least some individual grains of the ceramic adjoin one another with little to no intermediate amorphous material such that a thickness of amorphous material between two adjoining grains is less than 5 nm. In some embodiments, the body has less than 10% porosity by volume and/or the body has closed pores. In some embodiments, the grains comprise lithium, and the body has ionic conductivity of greater than 5×105 S/cm. In some embodiments, the body has a particularly fine grain size, that being 5 μm or less. In some embodiments, the tape further includes an electrically-conductive metal coupled to the first major surface of the body, where in some such embodiments the body comprises a repeating pattern of vias, and the electrically-conductive metal is arranged in a repeating pattern. In some embodiments, the first and second major surfaces have a granular profile, the tape further includes a coating overlaying the granular profile of the first major surface, and an outward facing surface of the coating is less rough than the granular profile of the first surface, where electrically-conductive metal coupled to the first major surface is so coupled by way of bonding to the outward facing surface of the coating. In some embodiments, the inorganic material has viscosity of 12.5 poise at a temperature greater than 900° C.
Additional aspects of the present disclosure relate to a roll of the tape of any one of the above-described embodiments, wherein the tape is wrapped around and overlapping itself, bent to a radius of less than 30 cm.
Still other aspects of the present disclosure relate to a plurality of sheets cut from tape of any one of the above-described embodiments.
Some aspects of the present disclosure relate to a tape, comprising a body comprising ceramic grains sintered to one another, the body extending between first and second major surfaces, where the body has a thickness defined as distance between the first and second major surfaces, a width defined as a first dimension of the first major surface orthogonal to the thickness, and a length defined as a second dimension of the first major surface orthogonal to both the thickness and the width; where the tape is thin, having a thickness in a range from about 3 μm to about 1 mm; and where first and second major surfaces of the tape have a granular profile, and at least some individual grains of the ceramic adjoin one another with little to no intermediate amorphous material such that a thickness of amorphous material between two adjoining grains is less than 5 nm.
Some aspects of the present disclosure relate to a tape, comprising a body comprising ceramic grains sintered to one another, the body extending between first and second major surfaces, where the body has a thickness defined as distance between the first and second major surfaces, a width defined as a first dimension of the first major surface orthogonal to the thickness, and a length defined as a second dimension of the first major surface orthogonal to both the thickness and the width; where the tape is thin, having a thickness in a range from about 3 μm to about 1 mm; where first and second major surfaces of the tape have a granular profile; and where the grains comprise lithium and the body has ionic conductivity greater than 5×105 S/cm.
Additional features and advantages will be set forth in the detailed description that follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims.
The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and the operation of the various embodiments.
Referring generally to the figures, various embodiments of a system and process for manufacturing long, thin and/or wide sintered articles are shown and described, where by the term sinter Applicant refers to the process of coalescing (e.g., directly bonding to one another) particles or grains (e.g., of a powdered or granular material) into a solid or porous body by heating the particles or grains without completely liquefying the particles or grains such that crystal structure of the particles or grains remain in the coalesced body, however aspects of the present inventive technology may be used to manufacture amorphous material, such as those that are difficult or impossible to process using conventional manufacturing techniques, as may be intuitive to those of skill in the art of inorganic material processing. In addition, Applicant has discovered that new sintered articles having a variety of properties may be formed using the systems/processes discussed herein that were previously unachievable utilizing prior technology. Specifically, Applicant has developed material handling systems and processes that allow for a very precise level of control of a variety conditions/forces that the material experiences during formation of the sintered article, and that this precise control/material handling allows for production of long, thin and/or wide sintered tape materials believed to be unachievable with prior systems. Further, articles manufactured using technology disclosed herein may have other unique qualities, such as: strength, such as may be due to low number defects; purity, such as may be due to controlled airflow and sintering duration, and properties related to purity, such as dielectric constant and impermeability; consistency, such as along a length and/or widthwise, such as in terms of flatness, thickness, roughness, grain size, etc.; and other unique attributes.
In general, the system described herein utilizes an input roll of web supported green tape wound on a spool or reel. As explained in more detail below, the web supported green tape includes a green tape material including grains of inorganic material (e.g., such as grains of ceramic material, grains of polycrystalline ceramic material, metal grains or grains of synthetic material) bound with an organic binder material, and the green tape material is supported on carrier web (e.g., a sheet of polymer material). The input roll of web supported green tape is unwound, and the carrier web/backing layer is carefully separated from the green tape material. Applicant has found that by precisely controlling separation of the carrier web from the green tape with little or no distortion of the green tape, a sintered article having various properties (e.g., thickness, flatness, density, shape etc.) that are very consistent/controlled along its length can be produced. With that said, in other contemplated embodiments the green tape may not be web supported and/or may not be on a roll, such as if the tape is formed in-line, such as along the manufacturing line prior to sintering.
Following removal of the carrier web, the self-supporting green tape (including the grains of inorganic material supported by organic binder material) is moved through a binder removal station. In general, the binder removal station applies heat to the self-supporting green tape in a manner that removes or chemically alters the organic binder such that the tape material exiting the binder removal station is an unbound tape material. By unbound, Applicants refer to the binder material having been removed, however the unbound tape may still hold together, such as via char of the burned binder or by interweaving or bonding between the inorganic particles, or by other means (e.g., electrostatic forces, air pressures). Following removal of the organic binder, the unbound tape material is moved into a sintering station that applies heat to the unbound tape material that sinters (e.g., fully sinters or partially sinters) the inorganic particles forming a sintered article which exits the sintering station.
Applicant has found that, surprisingly, the grains of inorganic material will support themselves as an unbound tape material even after the organic binder is removed and/or that the tape may be otherwise supported, as described above. However, following removal of the organic binder, the unbound tape material is very delicate prior to sintering or may be very delicate prior to sintering. Thus, Applicant has further identified a new binder removal and sintering station arrangement that allows for handling of the delicate unsupported tape material in a manner that allows for production of very high quality sintered articles. (By unsupported in the preceding sentence, Applicant means unsupported by organic binder after the binder has been removed or burned.) In particular, wide, long, high quality sintered articles suitable for roll to roll handling are produced without introducing substantial distortion or without breaking the article during binder removal or sintering.
In particular, Applicant has identified that air flow (e.g., turbulent air flow generated by thermal gradients) within the binder removal station and/or sintering station may impinge upon the tape material causing distortion or breakage of the tape material. Further, Applicant has discovered that a highly horizontal processing path within the binder removal station and/or sintering station reduces or eliminates turbulent airflow which in turn produces or may produce sintered articles without significant distortion. Further, Applicant has determined that eliminating air flow based distortion is particularly important when forming wide sintered articles (e.g., articles having width greater than 5 mm) because Applicant believes that susceptibility to air flow based distortion increases as the width of the tape material increases. Further, Applicant has determined that eliminating or reducing air flow based distortion is particularly important to allow for roll to roll processing as Applicant has found that even minor levels of distortion may cause the sintered article to break or otherwise not wind properly on the uptake reel (also called a tape-up reel).
Identification of horizontal positioning of the tape during binder removal and/or sintering was a surprising discovery given the inorganic green material and prior sintering technologies. For example, some tape material sintering may use downwardly angled positioning (e.g., a 12 to 20 degree downward incline) of the tape material as a means of utilizing gravity to pull the delicate tape material through the heating steps of the system, possibly intended for application of an evenly distributed force across the tape material to pull the tape material through heating steps of the process.
However, Applicant has discovered that when the heating portions of a sintering system are positioned at an incline, turbulent air flows may form as the hot air rises through channels of the heating system that holds the tape material. Thus, this flowing air impinges on the tape material, possibly forming distortions or potentially breaking the tape. Further Applicant discovered that incidence of air flow based distortions created in the sintered tape formed using a non-horizontal heating arrangement may increase as the width of the tape material increases. With that said, aspects of technology disclosed herein may be used with systems that include non-horizontal heating channels or systems, such as a binder removal station. Further, aspects of technology disclosed herein, such as unique materials and form factors (e.g., thin ribbons of garnet or other materials or geometries), may be manufactured using non-horizontal heating channels or systems.
Applicant attempted to sinter a wider tape (e.g. a tape having a width greater than 5 mm, and specifically a green tape of 25 microns thickness, width of 32 mm, with zirconia—3 mole % Y2O3 inorganic particles) using an incline arrangement. As shown in
In addition to air flow control, Applicant has identified that control of the thermal profiles within the binder removal station and/or sintering station is or may be important to forming a high quality sintered article. In particular, Applicant has discovered that when heating a wide tape material in a roll to roll process, such as the one discussed herein, the thermal stresses that the tape material is exposed to, particularly during sintering, should be precisely controlled to limit distortion or breakage that may otherwise occur as the tape material shrinks/densifies during sintering for at least some materials and/or forms disclosed herein, such as at least some thin, wide tapes of inorganic material. As an example shown in
Thus, as shown and described below, Applicant has determined that by utilizing a sintering furnace with independently controlled heating zones and/or multiple independently controlled sintering furnaces, a wide, long segment of tape material may be sintered without significant distortion and/or breakage at a high process throughput rate. Similarly, the binder removal furnace and sintering furnaces are designed and positioned relative to each other to limit the thermal shock (e.g., exposure to a sharp temperature gradient) that the tape is exposed to as the tape transitions between different heated zones within the system discussed herein.
Following sintering, the wide, sintered tape is or may be wound onto an uptake reel forming a roll of sintered tape material. In contemplated embodiments the roll is cylindrical or otherwise shaped, such as when rolled around geometry that is not circular, such as oblong, triangular with rounded vertices, etc. Because of the high quality (e.g., low distortion) of the tape formed by the system(s) discussed herein, in at least some embodiments the tape may be wound into a roll in a manner that allows for the sintered tape roll be used conveniently and efficiently in subsequent manufacturing processes, e.g., as a substrate in downstream, roll-to-roll manufacturing processes. Applicant has found that the high level of width, length, thickness, shape and/or flatness consistency and/or other attributes (purity, strength, impermeability, dielectric performance) of the tape or other articles produced by the system(s) discussed herein allows for spooling of the tape on the uptake reel. In contrast, a tape with high levels of distortion or irregularities would or may tend to break or otherwise form a distorted, inconsistent tape roll and may be unsuitable for uptake onto a reel to form a roll of sintered tape. With that said, some contemplated non-horizontal sintering systems, especially those that employ technology disclosed herein, may allow for undistorted tapes, such as if air flow is controlled, the tape is thin enough and sufficiently tensioned, the rate of sintering and temperatures are controlled, for example, as disclosed herein.
Lastly, some conventional sintered articles are formed in systems in which discreet unsintered pieces or pieces of green tape are placed upon a surface, called a setter board, and placed inside a furnace that burns off the organic binder and sinters the inorganic grains. Applicant has identified that roll-to-roll formation of a sintered article will provide a number of advantages not found by discreet, conventionally sintered articles. For example, wide, wound rolls of sintered articles can be formed at high throughput speeds (e.g., speed of 6 inches per minute or greater). In addition, system(s)/process(es) discussed herein forms wide, thin sintered (e.g., thin ceramic and/or sintered articles) which allows for use of the sintered article as a substrate to form small and low cost devices (e.g., semi-conductor devices, batteries, etc.). Similarly, providing a roll of sintered material allows the sintered material be used as an input substrate roll to high throughput downstream manufacturing processes, further allowing for downstream articles to be formed at high speed and/or at low cost utilizing the sintered articles discussed herein.
System OverviewReferring to
In general, continuous tape material 18 includes a layer of green tape material 20 that includes grains of inorganic, sinterable material bound together with an organic binder (e.g., (e.g., polyvinyl butyral, dibutyl phthalate, polyalkyl carbonate, acrylic polymers, polyesters, silicones, etc.). The green tape material 20 of the continuous tape material 18 is or may be supported on a carrier web or backing layer 22. As will be discussed in more detail below, in specific embodiments, system 10 is configured to form long, wide and/or thin sintered articles and in such embodiments, the green tape material 20 coming into the system 10 is also relatively long, wide and/or thin. For example, in specific embodiments, green tape material 20 has a width greater than 5 mm, greater than 10 mm, greater than 40 mm or greater than 125 mm. In specific embodiments, green tape material 20 has a length greater than 10 meters (m), specifically greater than 30 m, and more specifically greater than 60 m. In specific embodiments, green tape material 20 has a thickness between 3 microns and 1 millimeter. In addition, incoming green tape material 20 has a porosity that is greater than the porosity of the sintered article produced by system 10. In other contemplated embodiments, the green tape material 20 may have a width less than 5 mm, such as at least 0.5 mm, at least 1 mm, at least 2.5 mm, or smaller than 0.5 mm in some such embodiments. Similarly, the tape may have another thickness and/or length and/or porosity. In some embodiments, the tape material 20 may have a non-rectangular cross-section orthogonal to its length, such as round, oblong, parallelogram, rhomboid, etc., where, as may be intuitive, width of such embodiments refers to a maximum cross-sectional dimension orthogonal to length and thickness is a minimum cross-sectional dimension orthogonal to length.
Separation system 12 includes carrier web removal station 24. At carrier web removal station 24, carrier web 22 is separated from green tape material 20, and the removed carrier web 22 is or may be wound onto an uptake reel 26. In general, carrier web removal station 24 includes a tension isolator 28, which can include a vacuum drum, and a peeler 30 that removes carrier web 22 in manner that does not distort or compress green tape material 20 and that isolates the tension within carrier web 22 generated by uptake reel 26 from green tape 20. Following separation from carrier web 22, green tape 20, is or may be a self-supporting green tape including the grains of inorganic material supported by the organic binder material, but does not include a carrier web or other support structure to hold the tape material together during downstream processing through system 10.
Self-supporting green tape 20 moves or may move into an ultralow tension control system 32. In general, self-supporting green tape 20 is a relatively delicate structure that is being pulled through system 10 via the operation of various spools, reels, rollers, etc. The pulling action imparts a tension to self-supporting green tape 20. Applicant has found that a uniform, low level (e.g., gram levels; 0.1 grams to less than 1 kg; at least 1 gram, at least 5 grams, and/or no more than 100 grams, depending upon the tape size and binder strength) of tension applied to self-supporting green tape 20 is or may be advantageous as it improves various characteristics, such as cross-width shape and flatness of the final sintered article. However, due to the delicate nature of the self-supporting green tape 20 (which becomes even more delicate following binder removal as described in more detail below), the low level of tension is precisely controlled such that enough tension is provided to tape 20 to limit distortion during binder removal/sintering of tape 20 while also limiting maximum tension to ensure tape 20 does not break. With that said, in other contemplated embodiments, greater tension, such as for stronger tapes, or zero tension, other than tension due to weight of the tape itself, is applied.
In one or more embodiments, as shown in
Following tension control system 32, self-supporting green tape 20 moves into binder removal station 34. In general, binder removal station 34 includes one more heating element that delivers heat to a channel formed with the station 34. Heat within binder removal station 34 chemically changes and/or removes at least a portion of the organic binder material of self-supporting green tape 20 such that an unbound tape 36 exits binder removal station 34. In general, unbound tape 36 includes the grains of inorganic material with very little or no organic binder remaining. Applicant has found that unbound tape 36 will hold itself together even without the presence of the organic binder in manner that allows the unbound tape 36 to be moved into sintering station 38, such as utilizing the tension-control, air flow control, proximity of the binder removal station 34 to the sintering station 38 and temperature control therebetween, orientation and alignment of the tape and stations 34, 38 as shown in
In general, binder removal station 34 is arranged and controlled in a manner that provides for low distortion of tape 20 as it traverses the binder removal station 34. Further, binder removal station 34 may include heating elements that allow for removal of volatile organic compounds without applying too much heat too quickly, which otherwise may ignite the organic binder compounds. Ignition may also be controlled by air flow.
In addition, binder removal station 34 is positioned in manner relative to sintering station 38 such that the thermal shock or temperature gradient that unbound tape 36 is exposed to during movement from binder removal station 34 into sintering station 38 is low (e.g., spaced apart, but with pathways aligned linearly and respective openings aligned and/or close to one another, such as within 1 m, such as within 10 cm, such as within 2 cm, and/or closer). Applicant has found that due to the delicate nature of unbound tape 36, limiting the thermal shock experienced by the tape 36 between stations 34 and 38 further provides for production of flat, consistent and/or unwarped sintered tape by limiting/eliminating distortion that would otherwise occur due to the temperature gradients experienced between stations 34 and 38.
In various embodiments, temperature within station 34 is precisely controlled to achieve the desired properties of tape 36 leaving station 34. In various embodiments, the temperature within station 34 is between 200 degrees Celsius (° C.) (or about 200° C.) and 500° C. (or about 500° C.), and station 34 is heated to provide a temperature profile along its length such that very little or no binder material remains within the tape material exiting binder removal station 34. Further, in some embodiments, some sintering (e.g., shrinkage, increase in density, decrease in porosity, etc.) of the grains of inorganic material may occur during traversal of binder removal station 34.
Following binder removal in station 34, unbound tape 36 moves into the sintering station 38. In general, sintering station 38 includes one or more heating element (see, e.g., further discussion of heating elements and types thereof below) that heats sintering station 38 to temperatures above 500 degrees ° C. (e.g., between 500° C. (or about 500° C.) and 3200° C. (or about 3200° C., such as 3200° C.+10% of 3200° C.)) which causes sintering of the grains of inorganic material of unbound tape 36. In general, the porosity of the inorganic material decreases during sintering. This decrease in porosity may also result in a shrinkage (e.g., a reduction in width, thickness, length, etc.) of the tape material as the material is sintered, such as in sintering station 38. With some materials, during sintering, the elastic modulus can increase, the strength can increase, the shape of the porosity can change, without a significant decreasing in porosity or significant shrinkage. In some embodiments, the sintering station 38 transforms the tape 38 into a bisque material that is partially, but not fully sintered.
Applicant has found that as unbound tape 36 traverses sintering station 38, the unbound tape 36 is susceptible to deformation or breakage which may be caused by a variety of forces that the unbound tape 36 encounters during sintering. In particular, as noted above, Applicant has discovered that forces caused by turbulent air flow through sintering station 38 is one source of significant deformation, and Applicant has also found that the stress internal to tape 36 during sintering is another significant potential source of deformation. Based on these discoveries, Applicant has arranged or configured sintering station 38 in variety of ways in order to limit these forces to produce a sintered article having acceptably low levels of distortion.
In particular, as shown in
As shown in the embodiment of
In addition, Applicant has discovered that if unbound tape 36 is exposed to a temperature profile along the length of sintering station 38 that has drastic rises/drops in temperature, high levels of stress are or may be generated within tape 36 which in turn causes or may cause deformation or breakage of tape 36 during sintering. Further, Applicant has discovered that the sintering stresses increase the risk of deformation as the width of tape 36 increases. Thus, based on these discoveries, Applicant has determined that by utilizing a sintering station 38 with multiple, independently controllable heating elements (and potential multiple sintering furnaces), a temperature profile along the length sintering station 38 can be generated that keeps the stress with tape 36 below a threshold that Applicant has discovered that tends to causes deformation or breakage based on a particular tape configuration.
Following traversal of sintering station 38, a partially or fully sintered tape material 40 exits sintering station 38 and enters the output side, uptake system 42. Sintered tape material 40 is wound upon uptake reel 44. An interlayer support material 46 is paid off of a reel 48. Support material 46 is wound unto uptake reel 44 such that a layer of support material 46 is or may be located between each layer or at least some layers of sintered tape material 40 on uptake reel 44. This arrangement forms a roll or spool of supported sintered tape material 50. In general, support material 46 is a compliant, relatively high friction material that allows sintered tape material 40 to be held on to uptake reel 44 at a relatively low wind tension. The compliance of support material 46 can compensate for cross-web shape that may be present in tape 40 (sintered tape material 40). The support material 46 also increases friction between adjacent layers of tape 40 (sintered tape material 40) on reel 44 which limits tape 40 (sintered tape material 40) from sliding/telescoping of reel 44. Applicant believes that without support material 46, sintered tape material 40 tends to slide off (e.g., telescope) of spool 50 at least in part because the modulus of sintered tape 40 (sintered tape material 40) is relatively high, limiting the ability of tape 40 (sintered tape material 40) to stretch under wind tension, which in turn tends to or may result in poor roll integrity.
As discussed herein, system 10 is configured to form a sintered tape material 40 having low levels of distortion, low level risk of breakage, consistent properties along its length, etc. despite the width and/or length of the sintered article. As Applicant has discovered, the risk of distortion and breakage of tape at various stages of system 10 may increase, particularly as the width of the tape increases. For example, in specific embodiments, sintered tape 40 (sintered tape material 40) has a width greater than 5 mm, greater than 10 mm, greater than 40 mm or greater than 125 mm, and the various arrangements of system 10 discussed herein limit the deformation or breakage risk despite the width of the tape material. In other embodiments the sintered tape has a width less than 5 mm and/or at least 0.5 mm, such as at least 1 mm, such as at least 2 mm.
In addition, the various material handling and heating mechanism(s) of system 10 allow for sintered tape 40 (sintered tape material 40) to be formed at a high throughput rate. In specific embodiments, the roll to roll processing of system 10 allows for production of sintered tape at speeds believed to be substantially faster than other sintering processes, such as tunnel kiln processing in at least some instances, such as conventional tunnel kiln processing. In specific embodiments, system 10 is configured to produce sintered tape 40 at a rate of at least 6 inches per minute, at least 8 inches per minute, at least 19 inches per minute, at least 29 inches per minute, and at least 59 inches per minute. In yet additional specific embodiments, system 10 is configured to produce sintered tape 40 at a rate of at least 3 inches per minute for green tape 20 having a width greater than 50 mm, of at least 5 inches per minute for green tape 20 having a width between 35 mm and 50 mm, of at least 9 inches per minute for green tape 20 having a width between 15 mm and 35 mm, and of at least 10 inches per minute for green tape 20 having a width between 5 mm and 15 mm. In additional specific embodiments, system 10 is configured to produce sintered tape 40 at a rate of at least 1 inches per minute (ipm) for green tape 20 having a width greater than 50 mm, of at least 1.5 inches per minute for green tape 20 having a width between 35 mm and 50 mm, of at least 2 inches per minute for green tape 20 having a width between 15 mm and 35 mm, and of at least 3 inches per minute for green tape 20 having a width between 5 mm and 15 mm.
Support Web Removal StationFormation of the embodiments of the sintered articles described herein includes applying a uniform web tension to the green tape material before and after sintering. The separation system according to one or more embodiments of this disclosure is designed to apply such uniform web tension, along with uniform velocity, to a green tape material as it is separated from a supporting carrier web. Accordingly support of web removal, as disclosed herein, allows for consistency of the shape of the green tape material, reducing or eliminating instances of necking or contracting of the green tape as well as reducing or eliminating instances of imprinting features of surfaces of the equipment on the green tape, which in turn may otherwise be present in the sintered tape. With that said, technology disclosed herein may be used without the support web removal station to produce new sintered tapes as disclosed herein, where the tapes may have characteristics attributed to the lack of support web removal station, such as changes in thickness, repeating imprinted surface features, etc.
As noted above, system 10 includes a support web removal station generally at the input side of system 10. One aspect of the support web removal station includes a separation system 12. Referring to
According to an exemplary embodiment, the green tape material 20 includes grains of inorganic material (as described herein) that are sinterable and are bound together with an organic binder. The carrier web 22 may include a polymer, paper or a combination of a polymer and a paper material. In some embodiments, the green tape material includes an amount of polymer that is less than the polymer content of the carrier web 22, where polymer content is in terms of volume percent of the respective material. According to an exemplary embodiment, the green tape material 20 and the carrier web 22 each have a respective thickness (t) defined as a distance between the first major surface and the second major surface, a respective width (W) defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a respective length (L) defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width, such as for green tape having a continuous cross-sectional geometry that is rectangular or oblong (e.g., where edges may be removed after sintering to form straight sides). In other contemplated embodiments, a tape of inorganic, sinterable material may be held together by an inorganic binder, such as an inorganic binder that becomes part of the sintered tape after processing in the system 10. In still other contemplated embodiments, the tape of inorganic material may be held together by bonding of the inorganic material to itself, such as with a partially sintered bisque tape as opposed to green tape, as disclosed herein, for example.
As will be described herein, according to an exemplary embodiment, the carrier web 22 provides or may provide the primary contact surface for conveying the continuous tape material through the separation system 12 and, in particular conveying the continuous tape material through the carrier web removal station 24. In other words, in at least some such embodiments the carrier web 22 is primarily contacted, leaving the green tape material 20 substantially uncontacted and thus, is substantially free of defects or flaws that are or may be generated by contact, such as repeating surface features due to imprinting of the surface of a wheel or roller on the green material of the tape that may be detectable in a finished sintered product. Other embodiments may include such defects or flaws, such as when aspects of technology disclosed herein are used without the carrier web removal station 24, for example.
When the source 16 is a spool, the continuous tape material has a first tension, which is relatively low (as will be further described herein) and has a propensity to unwind at relatively high speeds even when the continuous material is held in a constant and low tension. The separation system 12 functions or may function as a brake to reduce or otherwise control or limit the speed of unwind of the continuous tape material from the source 16.
According to at least some such exemplary embodiments, the carrier web removal station 24 includes a tension isolator 28 positioned in proximity to and downstream from the source 16 and a peeler 30 positioned downstream from the tension isolator 28. The tension isolator 28 and peeler 30 separate the carrier web 22 from green tape material 20 without damaging the green tape material. In particular the tension isolator 28 is designed and used to grip the carrier web and pace the velocity of the continuous tape material through the separation system. In one or more embodiments, after the carrier web 22 is separated from the green tape material, the speed at which the carrier web 22 is collected after separation from the green tape material 20 is controlled to maintain constant tension in the carrier web 22, and thus in the continuous green tape material 20. In one or more embodiments, the tension isolator 28 isolates the separation of the carrier web 22 from the green tape material 20 from the quality of the incoming green tape material 20 from the source 16. Without the tension isolator 28, any or some inconsistencies in the wind quality of the continuous tape material (i.e. too loose a wind, which can result in cinching during unwinding or feeding to the peeler 30) can cause tension and velocity variations at the peeler 30.
According to an exemplary embodiment, the continuous tape material 18 is fed at a first tension to the tension isolator 28, and the tension isolator of one or more embodiments has a structure or is configured to apply a second tension to carrier web 22, which is greater than the first tension of the continuous tape material 18, when conveying the continuous tape material 18 to the peeler 30. In some embodiments, the second tension (i.e. tensile force) is at least 20% greater than the first tension and/or at least 25 millinewtons (mN) greater, such as at least 100 mN greater, such as at least 200 mN greater. According to some such embodiments, the second tension is applied to the carrier web 22, but not or at least substantially not applied to the green tape material. In one or more embodiments, the green tape material 20 maintains the first tension as the continuous tape material is moved along the tension isolator 28. In one or more embodiments, as the continuous tape material is moved along the tension isolator 28, the green tape material comprises or has no tension or no tension beyond tension to support its own weight, or substantially no tension beyond tension to support its own weight, such as less than 1 newton (N) beyond tension to support its own weight. Accordingly, the tension isolator 28 creates a first tension zone 17 between the tension isolator 28 and the source 16 and a second tension zone 19 between the tension isolator 28 and the peeler 30. The tension applied to the carrier web 22 in the first tension zone 17 is less than the tension applied to the carrier web 22 in the second tension zone 19. In one or more embodiments, the tension (i.e. tensile stress) applied to the carrier web 22 in the second tension zone 19 is about 2.5 pounds per (linear) inch (PLI) or less. For example, in one or more embodiments, the tension applied to the carrier web 22 is about 2.4 PLI or less, about 2.3 PLI or less, about 2.2 PLI or less, about 2.1 PLI or less, about 2 PLI or less, about 1.8 PLI or less, about 1.6 PLI or less, about 1.5 PLI or less, about 1.4 PLI or less, about 1.2 PLI or less, or about 1 PLI or less. In one or more embodiments, the first tension is equal to or less than about 50% (e.g., about 45% or less, about 40% or less, about 35% or less, about 30% or less, or about 25% or less) of the second tension. In some embodiments, tension (i.e. tensile force) applied to the carrier web 22 in the second tension zone 19 is at least 20% greater than tension applied to the carrier web 22 in the first tension zone 17 and/or at least 25 millinewtons (mN) greater, such as at least 100 mN greater, such as at least 200 mN greater. In one or more embodiments, (nominal) additional tension is applied to the green tape material, other than the tension that is applied on the green tape material through the application of tension on the carrier web 28. In such embodiments, the carrier web may stretch due to such application of tension on the carrier web, which in turn creates some tension on the green tape material, such as where the overwhelming bulk of tension is borne by the carrier web.
In one or more embodiments, the tension isolator 28 applies a tension to the carrier web 22 that is greater than the tension applied to the green tape material 20. In some embodiments, the tension isolator applies a tension to the carrier web that is equal to or greater than about 2 times the tension applied to the green tape material, as the continuous tape material is moved from the source 16 to the peeler 30. In some embodiments, the tension isolator 28 applies a tension to the carrier web 22 that is at least 20% greater than the tension applied to the green tape material 20 and/or at least 25 millinewtons (mN) greater, such as at least 100 mN greater, such as at least 200 mN greater. As may be intuitive, tension as used herein generally refers to the lengthwise or axial pulling apart of material and when given units of force herein, tension refers to tensile force, and when given units of stress, tension refers to tensile stress, and/or tension herein may be given other units and refer to another related parameter, such as pounds per linear inch or the metric equivalent.
In the embodiment shown in
In one or more embodiments, the tension isolator 28 increases tension in the continuous tape material (and more particularly in the carrier web or mostly the carrier web) along the second tension zone 19 as the continuous tape material is conveyed to the peeler 30. In the embodiment shown in
In one or more embodiments, the peeler 30 is disposed downstream from the tension isolator 28 and directs the carrier web 22 in a rewind direction A and directs the green tape material 20 in a downstream processing direction B that differs from the rewind direction A, as shown in
In one or more embodiments, the peeler 30 includes a sharp knife or edge to create a line of separation in the green tape material, such as at or proximate to the vertex of the angle C, shown as tip 31. In one or more embodiments, the sharp knife or edge creates a line of separation in the green tape material, but not the carrier web, just prior to a tip 31 or proximate to the tip 31, as shown in
As continuous tape material passes over the tip 31, the tip 31 separates the carrier web 22 from the green tape material 20. In one or more embodiments, the tip 31 separates the carrier web 22 from the green tape material 20 before directing the carrier web in the rewind direction A and directing the green tape material in the downstream processing direction B. In one or more embodiments, the tip 31 separates the carrier web 22 from the green tape material 20 simultaneously with directing the carrier web 22 in the rewind direction A and directing the green tape material 20 in the downstream processing direction B.
As shown in
Another aspect of the support web removal station pertains to a method for separating two materials (e.g., the green tape material and the carrier web). In one or more embodiments, the method includes feeding the continuous tape material 18 to the tension isolator 28, applying tension to the carrier web 22 that is greater than a tension applied to the green tape material 20 with the tension isolator, and directing the carrier web to move in the rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction, as described herein. In one or more embodiments, the method includes separating the carrier web from the green tape material before directing the carrier web in a rewind direction and directing the green tape material in the downstream processing direction. In one or more embodiments, the method includes separating the carrier web from the green tape material simultaneously with directing the carrier web in the rewind direction and directing the green tape material in the downstream processing direction. As taught above, embodiments of this method have the carrier web contacting the vacuum drum. In other embodiments, tape materials may have carrier webs on both sides of the tape, and elements of the separation station may be repeated and used to remove both carrier webs.
In one or more embodiments, the method includes applying no tension or substantially no or very little tension (as disclosed above) to the green tape material. In one or more exemplary embodiments, the method includes applying no tension or substantially no or very little tension to the green tape material as the continuous tape material moves from the source 16 to the tension isolator 28 along the first tension zone 17. In one or more exemplary embodiments, the method includes applying no tension or substantially no or very little tension to the green tape material as the continuous tape material moves from the tension isolator 28 to the peeler 30 along the second tension zone 19. In one or more embodiments, the method includes applying no tension or substantially no or very little tension to the green tape material 20 as the continuous tape 18 moves from the source 16 to the tension isolator 28 (along the first tension zone) and to the peeler 30 (along the second tension zone). In one or more embodiments, the method includes applying tension to the carrier web 22 that is at least two times greater than the tension applied to the green tape material 20 (at any point along the separation system 12). Selecting a carrier web with low elasticity may facilitate having the carrier web bear a bulk of tension applied to the tape material.
In one or more embodiments, the method includes applying no additional tension to the green tape material, other than the tension that is applied on the green tape material through the application of tension on the carrier web 28. In such embodiments, the carrier web may stretch due to such application of tension on the carrier web, which in turn creates some tension on the green tape material. In one or more exemplary embodiments, the method includes applying no additional tension to the green tape material as the continuous tape material moves from the source 16 to the tension isolator 28 along the first tension zone 17. In one or more exemplary embodiments, the method includes applying no additional tension to the green tape material as the continuous tape material moves from the tension isolator 28 to the peeler 30 along the second tension zone 19. In one or more embodiments, the method includes applying no additional tension to the green tape material 20 as the continuous tape 18 moves from the source 16 to the tension isolator 28 (along the first tension zone) and to the peeler 30 (along the second tension zone).
In one or more embodiments, the method for separating two materials (i.e., the green tape material and the carrier web) includes feeding the continuous tape material to the tension isolator and applying a first tension to the carrier web, applying a second tension to the carrier web that is greater than the first tension, and directing the carrier web to move in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction. In one or more embodiments, applying a first tension comprises applying no tension or little tension as disclosed herein. In one or more embodiments, applying a first tensions comprises applying no or little tension to the carrier web as the continuous tape material moves from the source 16 to the tension isolator 28 along the first tension zone. In one or more embodiments, the second tension is about 2.5 PLI or less. For example, in one or more embodiments, the tension applied to the carrier web 22 is about 2.4 PLI or less, about 2.3 PLI or less, about 2.2 PLI or less, about 2.1 PLI or less, about 2 PLI or less, about 1.8 PLI or less, about 1.6 PLI or less, about 1.5 PLI or less, about 1.4 PLI or less, about 1.2 PLI or less, or about 1 PLI or less. In one or more embodiments, the first tension is equal to or less than about 50% (e.g., about 45% or less, about 40% or less, about 35% or less, about 30% or less, or about 25% or less) of the second tension.
In one or more embodiments, the method includes at least partially sintering the green tape material (as will be discussed in more detail herein related to the sintering station), after it is separated from the carrier web 22. In one or more embodiments, the method includes spooling the carrier web 22 onto an uptake reel 26, after the carrier web 22 is separated from the green tape material 20. In one or more embodiments, the method includes continuously maintaining the tension on the carrier web 22 along the second tension zone and until the carrier web is spooled onto the uptake reel.
Binder Removal StationAs noted above regarding
According to an exemplary embodiment, as shown in
As discussed above, the green tape 20 includes grains of an inorganic material bound by a binder as disclosed herein, such as an organic binder. The binder removal station 34 receives the green tape 20 and prepares the green tape 20 for sintering by chemically changing the binder and/or removing the binder from the green tape 20, leaving the grains of the inorganic material, to form self-supporting, unbound tape 36, which may be moved in the processing direction 14 into sintering station 38, as discussed in more detail below. According to an exemplary embodiment, at an instant (i.e. a single moment in time) the green tape 20 simultaneously extends toward, into, through, within, adjacent to, and/or away from the station 34. Accordingly, as will be understood, the tape material being processed in system 10 simultaneously includes the green tape 20 which is continuously connected to unbound tape 36, as the tape material traverses binder removal station 34.
According to an exemplary embodiment, the binder of the green tape 20 may be a polymer binder and the binder is chemically changed and/or removed from the green tape 20 by heating the binder to burn or char the binder. According to an exemplary embodiment, the binder removal station 34 chars or burns at least most of the organic binder in terms of weight from the first portion of the green tape 20 without sintering the grains of the inorganic material, which can be measured by weighing the green tape before binder removal at the station 34 as well as the inorganic material prior to forming the green tape, then weighing the unbound tape 36 following operation of the binder removal station 34 and comparing differences. If remnants of the binder remain, such as carbon, Applicant believes that subsequent sintering, at higher temperatures, may generally remove those remnants. In other contemplated embodiments, the binder may be chemically removed, such as formed from a material selected to chemically react with another material (e.g., catalyst, gas) delivered to the green tape at a binder removal station prior to sintering. In still other contemplated embodiments, the binder may be evaporated or otherwise vaporized and outgassed from the green tape 20 at a station prior to sintering.
Still referring to
According to an exemplary embodiment, the active heater 5120 of the binder removal station 34 includes heating zones, such as zones 5120A, 5120B, 5120C, 5120D such that the rate of heat energy received by the green tape 20 increases as the green tape 20 advances through the binder removal station 34. In some embodiments, the rate of heat energy received by the green tape 20 increases in a nonlinear manner, such as slowly increasing at first, as the binder degrades and emits combustible gaseous byproducts, and then faster as the potential for the green tape 20 catching fire is reduced. This heat zone approach and more specifically the non-linear approach may be particularly useful for sintering of tapes, as disclosed herein, which may travel a manufacturing line, such as system 10, at a constant rate. According to an exemplary embodiment, temperatures experienced by the green tape 20 in the binder removal station 34 may be at least 200° C., such as at least 250° C., and/or below a sintering temperature for the inorganic grains carried by the green tape 20, such as less than 1200° C., such as less than 900° C. In contemplated embodiments, for at least some materials disclosed herein, the binder removal station 34 may sinter, at least to some degree, inorganic material of the tape, such as possibly bonding individual grains to one another, which may increase tensile strength of the tape.
According to an exemplary embodiment, the binder removal station 34 blows and/or draws gas over and/or under (e.g., over and under) the green tape 20 as the green tape 20 advances through the binder removal station 34. In some embodiments, the heater 5120 may provide a flow of hot air to communicate some or all of the heat energy to the green tape 20, as may be delivered through an array of nozzles through a wall from a plenum, or through a porous wall material. In other embodiments, flow of the gas is facilitated by fans or pumps adjoining the binder removal station 34, such as fan 5122 shown in
In some embodiments, gas is blown and/or drawn over both the topside and underside of the green tape 20, while in other embodiments, the gas is directed only over the topside or the underside. In some such embodiments, the green tape 20 is directly supported by a gas bearing and/or an underlying surface and moves relative to that surface. For example, the green tape 20 may slide along and contact an underlying surface, such as a surface made of stainless steel. In some embodiments the gas is heated to a temperature above room temperature before blowing or drawing it over the tape, such as to at least 100° C., which Applicants have found may help prevent thermal shock of the green tape 20, which may influence properties of resulting sintered material, such as providing increased strength or flatness due to fewer sites of surface irregularities and stress concentrations.
Actively blowing or drawing gas over the green tape 20, especially air or gas containing oxygen, may be counterintuitive to those of skill in the art because one might expect the oxygen to fuel and promote the tape catching fire, which could distort the shape of the green tape 20 and/or otherwise harm quality of the green tape 20 as tape 20 traverses station 34. However, Applicant has found that as the green tape 20 is conveyed through the binder removal station 34, blowing and/or drawing gas, including air in some embodiments, over the green tape 20 actually helps the tape not to catch fire. For example, Applicant has found that while the binder is removed and/or charred by the binder removal station 34 without catching fire, that the tape catches fire when moving at the same rate through the station 34 if air is not blown over the green tape 20. Applicant contemplates that risk of catching the green tape 20 on fire may also be reduced and/or eliminated by moving the green tape 20 slower through the binder removal station 34, further spacing apart the heat zones 5120A, 5120B, 5120C, 5120D, using flame retardants in the binder and increasing ventilation of the binder removal station 34, and/or combinations of such technologies.
While gas may be actively blown and/or drawn over the green tape 20 and/or the unbound tape 36, Applicant has found that the unbound tape 36 may be particularly susceptible to damage from vibration and/or out-of-plane bending depending upon how the gas flows. Accordingly, in some embodiments, the gas flowing through the binder removal station 34 is and/or includes laminar flow. The flow of the air may be diffused and/or may not be directed to the unbound tape 36. In some embodiments, a gas source or motivator (e.g., fan, pump, pressurized supply) delivers at least 1 liter of gas per minute through the binder removal station 34, such as through the passage 5128 (see
According to some embodiments, the green tape 20 advances horizontally, not vertically through the binder removal station 34. Orienting the tape horizontally may help control airflow through the binder removal station 34, such as by reducing a “chimney effect,” where hot gasses rise and pull too much air through the binder removal station 34, vibrating the unbound tape 36. Air pumps, fans, and surrounding environmental air conditions (e.g., high temperatures) offset and/or control the chimney effect without horizontally orienting the green tape 20 through the binder removal station 34 in other contemplated embodiments.
According to an exemplary embodiment, the unbound tape 36 is under positive lengthwise tension as the green tape 20 advances through station 34. Tension in the green tape 20 may help hold the green tape 20 in a flat orientation, such as if the green tape 20 subsequently passes into another station of the manufacturing system for further processing, such as a sintering station 38. Without the binder (e.g., following binder removal in station 34), the unbound tape 36 may be weaker than the green tape material 20, such as having lesser ultimate tensile strength, such as half or less, such as a quarter or less. According to an exemplary embodiment, lengthwise tension (i.e. tensile stress) in the unbound tape 36 is less than 500 grams-force per mm2 of cross section. Applicant believes the green tape 20 is substantially more bendable than the unbound tape 36 such that a minimum bend radius without fracture of the green tape 20 is less than half that of the unbound tape 36 (e.g., less than a quarter, less than an eighth), when measured via ASTM standards, see E290, where bend radius is the minimum inside radius the respective portions of the green tape 20 can bend about a cylinder without fracture.
In at least some embodiments, following processing through the binder removal station 34, the unbound tape material 36 moves into sintering station 38 (discussed in more detail below), which at least partially sinters the inorganic material of the unbound tape 36 to form sintered tape 40. Accordingly, for continuous processing, at an instant the green tape 20 is continuously connected to sintered tape 40 by way of the unbound tape 36.
In some such embodiments, binder removal station 34 is close to the sintering station 38 such that distance therebetween is less than 10 m (e.g., less than 10 mm, less than 2.5 cm, less than 5 cm, less than 10 cm, less than 25 cm, less than 100 cm, less than 5 m, etc. between the outlet opening of the binder removal station 34 and the entrance opening 106 (see
Referring now to
Referring to
In some such embodiments, the step of preparing the tape for sintering 5214 further comprises charring or burning at least most of the binder from the first portion of the tape (e.g., as discussed above) with or without contemporaneously sintering the grains of the inorganic material. In some embodiments, the station of the manufacturing system is a first station and the method of processing 5210 further comprises steps of receiving the second portion of the tape at a second station 5218, and at least partially and/or further sintering the inorganic material of the second portion of the tape 5220 at the second station to form a third portion of the tape.
In some embodiments, the method of processing 5210 further comprises positively tensioning the second portion of the tape as the tape advances 5212. In some such embodiments, positively tensioning is such that lengthwise tension (i.e. tensile stress) in the second portion of the tape is less than 500 grams-force per mm2 of cross section. In some embodiments, the method of processing 5210 further comprises blowing and/or drawing gas over the tape while preparing the tape for sintering 5214. In some embodiments, the step of advancing the tape 5212 further comprises horizontally advancing the tape through the station, and/or directly supporting the tape by a gas bearing and/or an underlying surface and moving the tape relative to that surface and/or relative to the opening 5128.
Example of Binder RemovalApplicant has used a binder burn-out furnace similar to binder removal station 34 to remove binder from green tape prior to sintering. In one example, the green tape was tape cast zirconia ceramic grains loaded with polymer binder forming a ribbon of about 42 mm wide and about 25 μm thick. The green tape was feed through a horizontal six-hot-zone binder burnout furnace at 20 inches per minute. The binder burnout furnace was set at 325° C. inlet to 475° C. outlet with 0 to 25° C. increasing degree increments for the other four hot zones. About 7.5 liters per minute of air flow at temperatures 0 to 250° C. was also provided. The air flow was divided between both sides of the binder burn-out furnace. The furnace was 36 inches long and had an 18-inch hot zone.
Sintering StationReferring to
In at least one specific embodiment, sintering station 38 includes a sintering furnace 100. Sintering furnace 100 includes an insulated housing 102. In general, insulated housing 102 includes a plurality of internal walls that define a channel 104 that extends through sintering furnace 100 between an entrance, shown as entrance opening 106, and an exit, shown as exit opening 108. Binder removal station 34 is located adjacent to entrance opening 106 such that green tape material 20 passes through binder removal station 34 producing unbound tape material 36 as described above. Unbound tape material 36 passes into entrance opening 106 and through channel 104. While within channel 104, heat generated by a heater (explained in more detail below, and above with regard to different types of heating elements) causes sintering of unbound tape 36 to form sintered tape 40, and sintered tape 40 passes out through exit opening 108 for further processing or uptake as shown in
As can be seen in
As noted above, Applicant has found that a high level of horizontality of channel 104 and/or of unbound tape 36 within channel 104 reduces the effect of turbulent air flow on tape 36 during sintering. As shown in
To further control or limit turbulent air flow that the tape material of system 10 is exposed to during traversal of system 10, binder removal station 34 may be positioned relative to sintering station 38 in manner that maintains the tape material (e.g., green tape material 20 within binder removal station and unbound tape material 36 within sintering station) in a substantially horizontal position as tapes 20 and 36 traverse binder removal station 34 and sintering station 38. In such embodiments, similar to the horizontal positioning of sintering channel 104, binder removal station 34 is or may be also oriented in a substantially horizontal position, such as where openings 116, 118 are aligned to form a line therebetween that is within 10 degrees of horizontal.
In such embodiments, binder removal station 34 includes a binder burn out furnace 110. Binder burn out furnace 110 includes an insulated housing 112. In general, insulated housing 112 includes a plurality of internal walls that defines a channel 114 that extends through binder burnout furnace 110 between an entrance opening 116, and an exit opening 118.
As shown in
In addition to maintaining horizontality of green tape 20 and unbound tape 36 within binder burnout furnace 110 and sintering furnace 100, respectively, binder burnout furnace 110 (also called binder removal station) and sintering furnace 100 are aligned relative to each other such that unbound tape 36 maintains a horizontal position as unbound tape 36 transitions from binder burnout furnace 110 to sintering furnace 100. Applicant has found that at this transition point, unbound tape 36 is particularly susceptible to deformation or breakage due to various forces (such as force caused by turbulent airflow) because with most of the organic binder removed, the unsintered inorganic grains of unbound tape 36 are held together by relatively weak forces (e.g., Van der Walls forces, electrostatic interaction, a small amount of remaining organic binder, frictional interaction/engagement between adjacent particles, low levels of inorganic carried in the binder, plasticizer, liquid vehicle, perhaps some particle-to-particle bonding etc.), and thus, even relatively small forces, such as those cause by turbulent airflow interacting with unbound tape 36, can cause deformation or breakage.
Thus, as shown in
Applicant has determined that a benefit of horizontal binder removal and/or horizontal sintering becomes more important as the width of the tape material increases because wider tape materials are more susceptible to airflow turbulence-based deformation. Thus, Applicant believes that the horizontal arrangement of sintering furnace 100 and/or binder burnout furnace 110 allows for production of wider and/or longer sintered tape materials without significant deformation or breakage believed not achievable using prior systems.
Referring to
As shown in
As noted above, in various embodiments, G1 and G2 are relatively small such that turbulent air flow is limited, but G1 and G2 should generally be large enough that various processing steps (e.g., threading of channel 104 for example) are possible. In various embodiments, G2 is less than 0.5 inches (less than 12.7 mm), specifically is less than 0.375 inches (less than 9.5 mm) and more specifically is 0.25 inches (about 6.35 mm). As will be understood, G1 is generally equal to G2 plus the thickness T1 of unbound tape 36. Thus, in various embodiments, because T1 is relatively low, e.g., between 3 microns and 1 millimeter, G1 is less than 1 inch (less than 25.4 mm), specifically less than 0.75 inches (less than 19 mm), and for thin tape materials may be less than 0.5 inches (less than 12.7 mm), and for very thin tape materials may be less than 0.375 inches (less than 9.5 mm).
In specific embodiments, surface 120 and/or surface 122 are also substantially horizontal surfaces (as described above) that extend between entrance 106 and exit 108 of furnace 100. In such embodiments, surfaces 120 and 122 therefore define a substantially horizontal channel 104. In some specific embodiments, surfaces 120 and/or 122 may be flat, planar horizontal surfaces extending the entire distance between entrance 106 and exit 108 of furnace 100. In other specific embodiments, surfaces 120 and/or 122 may be gradually arcing or curving as described above, as may also be the case with the binder removal station. In specific embodiments, surfaces 120 and/or 122 are substantially horizontal such that the surfaces form an angle less than 10 degrees, specifically less than 3 degrees and even more specifically less than 1 degree relative to the horizontal reference plane.
As shown in
In addition the positional arrangements and airflow control arrangements discussed above, Applicant has also found that control of the temperature profile through furnace 100, that unbound tape 36 is exposed to, is important to limit tape deformation or breakage, which Applicant has discovered may occur if the temperate rise is too fast (e.g., sintering rate is too fast or over too short a distance in the tape). In general referring to
In general, each heating element 140 may be under the control of a control system 142 which is configured (e.g., physically arranged, programmed, etc.) to independently control individual heating elements 140 of the furnace 100 to generate a temperature profile along the length of channel 104 to provide the desired level of sintering in sintered tape 40, while limiting deformation during sintering. In some embodiments, control system 142 may be in communication with one or more temperature sensors 144, which detects temperature within channel 104. In such embodiments, control system 142 may control heating elements 140 based on an input signal received from sensor 144 such that a desired temperature profile is maintained during continuous sintering of continuous unbound tape 36. In some embodiments, control system 142 may also receive input signals indicative of tape movement speed, position, shrinkage, and tension and control temperature and/or movement speed based on these signals or other signals, which may be related to these or other tape properties.
As will be demonstrated in relation to the sintering furnace examples set forth below, Applicant has discovered that application of a sintering temperature profile along the length of channel 104 is or may be important to maintaining a low or controlled level of deformation in the tape material during sintering. In particular, Applicant has discovered that if the rise of temperature that unbound tape 36 is exposed to during sintering is too great (e.g., the slope of the temperature profile is too steep), unacceptably high levels of stress are or may be formed within tape 36 as the material sinters and shrinks, which in turn results in out of plane deformation in tape 36, such as that shown in
Referring to
As shown in
In various embodiments, the gradual temperature rise represented by the low slope of section 164 may be achieved by controlling the rate of temperature increase along the length of channel 104. In various embodiments, as represented by the x-axis in the plot of
In various embodiments, profile 160 is shaped to maintain an acceptably low level of compressive stress within tape 36 during sintering such that undesirable deformation is avoided. Applicant has discovered that tape deformation, if not controlled as discussed herein, is a challenge particularly for wide tape materials and high throughput sintering systems. In particular, wider tapes are more susceptible to this type of deformation, and in addition, width wise deformation makes or may winding on uptake reel difficult or impossible. With that said, aspects of the presently disclosed technology (e.g., carrier separation, tension control, binder removal, etc.) may be practiced and used to create new materials and products without the temperature profiles, such as where resulting products are narrower and/or have defects or deformation characteristic of such processing.
Thus, in various embodiments, profile 160 is shaped such that compressive stress at the left edge 130 and/or right edge 132 of unbound tape 36 during sintering remains below an edge stress threshold and that compressive stress at a centerline of the unbound tape 36 during sintering remains below a centerline stress threshold. In general, the edge stress threshold and the centerline stress threshold are defined as the compressive stresses above which unbound tape 36 experiences out of plane (length-width plane) deformation of greater than 1 mm during sintering. Applicant has discovered that for at least some materials and tape widths, out of plane deformation can be limited to below 1 mm during sintering by maintain the edge compressive stresses and centerline compressive stresses below thresholds of 100 MPa, specifically 75 MPa and more specifically 60 MPa. In a specific embodiment, Applicant has discovered that for at least some materials and tape widths, out of plane deformation can be limited to below 1 mm during sintering by maintaining centerline compressive stresses below thresholds of 100 MPa, specifically 75 MPa and more specifically 60 MPa, and by maintaining edge stresses below thresholds of 300 MPa, specifically 250 MPa and more specifically 200 MPa.
In a specific embodiment, the slope of sections 162 and 166 may be controlled to provide for particularly low tape stresses on entry to and exit from furnace 100. In one such embodiment, control system 142 is configured to control the temperature profile within sections 162 and 166 in combination with control of the speed of tape through furnace 100. In such embodiments, this combination of controlling temperature within sections 162 and 166, coupled with speed control, give a uniform sintering shrinkage (strain) and thus a low stress and low deformation within tape 36 during sintering.
Referring to
Referring to
In various embodiments, each furnace 180 and 182 includes a plurality of independently controllable heating elements such that a different and independent temperature profile can be formed in each furnace 180 and 182. In some embodiments, utilizing two thermally isolated furnaces, such as furnace 180 and 182, may provide more precise control of the temperature profiles that the tape material is exposed to during sintering, as compared to a single long furnace having the same channel length as the combined channel length of furnaces 180 and 182. In other contemplated embodiments, the tape can be moved back through the same furnace, but along a different path and/or exposed to a different temperature profile for additional sintering.
In addition, in some embodiments, application of differential tension between furnace 180 and 182 may be desirable. In such embodiments, a tension control system 186 is located along the sintering path defined by the channels 104 of furnaces 180 and 182. In specific embodiments, tension control system 186 is located between furnaces 180 and 182 and applies tension to partially sintered tape 184 such that the tension with tape 184 within second furnace 182 is greater than the tension with unbound tape 36 within furnace 180. In various embodiments, increasing tension in the second sintering furnace may be desirable to provide for improved flatness or deformation reduction during the final or subsequent sintering of furnace 182. In addition, this increased tension may be suitable for application to partially sintered tape 184 because the partial sintering increases the tensile strength of tape 184 as compared to the relatively low tensile strength of unbound tape 36 within furnace 180.
Referring to
Referring to
Referring to
In one example, a horizontal furnace with an actively controlled multiple zone binder burnout furnace was tested. In this test, a tape cast “green” zirconia ceramic ribbon (ceramic loaded with polymer binder), 42 mm wide and about 25 microns thick, was fed through a horizontal apparatus with the multi-zone binder burnout furnace (similar to furnace 38 and binder removal station 34 above) at 20 inches per minute. The binder burnout furnace was set at 325 degrees C. at the inlet to 475 degrees C. at the outlet with 0-25 increasing degree C. increments for the four central hot zones. Air flow at 7.5 liter per minute at a temperature range from about 0° C. to about 250° C. was also provided, and the air flow was divided between both sides of the burn out furnace. The sintering furnace was 36 inches long and had an 18 inch long hot zone. The tape was transported within the sintering furnace by sliding it over an alumina “D” tube, with a tension 20 grams and with the furnace set at 1225° C. A resulting 10-20 feet of sintered zirconia tape was made and spooled on a take-up reel 3 inches in diameter. Sintering shrinkage across the width was about 12%.
Sintering Model 1Referring to
To generate the data points shown in
From the sintering data, mathematical curves describing the sintering shrinkage as a function of temperature and time were fitted and extrapolated to lower and intermediate temperatures than those actually tested. This curve fitting and extrapolation is shown in
In one specific embodiment, this data was used to model the 64 inch sintering furnace and temperature profile shown in
Shrinkage was modeled as a function of tape transport speed. As shown in
Referring to
In another test example, a tape cast “green” zirconia ceramic ribbon (ceramic loaded with polymer binder) about 25 microns thick and 15 cm wide was made with a vertically-oriented sintering apparatus at a sintering temperature of 1100° C. About 50 feet was made and spooled on a take-up reel 3 inches in diameter. Bisque sintering shrinkage width was about 10%
This 1100° C. “bisque” tape was then passed through a horizontal sintering furnace, substantially the same as that shown in
In another test example, a tape cast “green” alumina ceramic ribbon (ceramic loaded with polymer binder) about 50 microns thick was fed through a system substantially the same as that shown in
The 1300° C. “bisque” tape was then passed through the sintering furnace a second time at 2 inches per minute with the sintering furnace set at 1550° C., producing about 20 feet of fully sintered alumina tape. The tape was spooled on a take-up reel 6 inches in diameter. Tension on the tape was about 100 grams during sintering, and sintering shrinkage width for the second pass was about 15%. After sintering, the tape was translucent, almost transparent. When set on a written document you could read through it. The grain size was below about 2 microns and the material had less than about 1% porosity.
Test Example 4In another test example, a tape cast “green” zirconia ceramic ribbon (ceramic loaded with polymer binder) about 50 microns thick was fed through a system substantially the same as that shown in
To physically model a furnace with a shallow temperature gradient, the 1225° C. sintered “bisque tape” was passed through the single zone furnace three times at progressively higher temperatures, which reduces the sintering shrinkage for each pass, reducing the out of plane deformation. Specifically, the 1225° C. “bisque” tape was then passed through the furnace a second time at 6 inches per minute with the furnace set at 1325° C. Via this process 45 feet of sintered zirconia tape was made and spooled on a take-up reel 3 inches in diameter. Tension on the tape during sintering was 100-250 grams, and sintering shrinkage width for this pass was 5-6%.
The 1325° C. tape was then passed through the furnace a third time at 6 inches per minute with the furnace set at 1425° C. About 40 feet of sintered zirconia tape was made and spooled on a take-up reel 3 inches in diameter. Tension on the tape during sintering was 100-250 grams, and sintering shrinkage width for this pass was 5-6%. After the 1425° C. pass the tape was translucent, almost transparent. When set on a written document you could read through it.
The 1425° C. tape was then passed through the furnace a fourth time at 3-6 inches per minute with the furnace set at 1550° C. A few feet of 1550° C. sintered tape was made and spooled on a take-up reel 3 inches in diameter. Tension on the tape during sintering was 100-300 grams and sintering shrinkage (width) for this pass was 0-2%.
Sintered ArticleEmbodiments of the sintered articles formed using the systems and processes described herein will now be described. The sintered articles may be provided in the form of a sintered tape (i.e., a continuous sintered article) or a discrete sintered article(s). Unless otherwise indicated, the term “sintered article” is intended to refer to both a continuous sintered article and a discrete sintered article(s). In addition, “sintered” refers to both partially sintered articles and fully sintered articles. In one aspect, embodiments of the sintered article comprise dimensions not previously achievable. In one or more embodiments, the sintered article also exhibit uniformity of certain properties along these dimensions. According to another aspect, embodiments of the sintered article exhibits a flattenability that indicates the sintered article can be flattened or subjected to flattening without imparting significant stress in the sintered article and thus can be used successfully in downstream processes. Another aspect pertains to embodiments of a rolled sintered article, and yet another aspect pertains to embodiments of a plurality of discrete sintered articles. Still other aspects include new compositions of materials, or compositions with new microstructures, such as in terms of unique grain boundaries, for example.
Referring to
In one or more embodiments, the sintered article is a continuous sintered article having a width of about 5 mm or greater, a thickness in a range from about 3 μm to about 1 mm, and a length in a range of about 300 cm or greater. In other embodiments, the width is less than 5 mm, as described above.
In one or more embodiments, the sintered article has a width in a range from about 5 mm to about 200 mm, from about 6 mm to about 200 mm, from about 8 mm to about 200 mm, from about 10 mm to about 200 mm, from about 12 mm to about 200 mm, from about 14 mm to about 200 mm, from about 15 mm to about 200 mm, from about 17 mm to about 200 mm, from about 18 mm to about 200 mm, from about 20 mm to about 200 mm, from about 22 mm to about 200 mm, from about 24 mm to about 200 mm, from about 25 mm to about 200 mm, from about 30 mm to about 200 mm, from about 40 mm to about 200 mm, from about 50 mm to about 200 mm, from about 60 mm to about 200 mm, from about 70 mm to about 200 mm, from about 80 mm to about 200 mm, from about 90 mm to about 200 mm, from about 100 mm to about 200 mm, from about 5 mm to about 150 mm, from about 5 mm to about 125 mm, from about 5 mm to about 100 mm, from about 5 mm to about 75 mm, from about 5 mm to about 50 mm, from about 5 mm to about 40 mm, from about 5 mm to about 30 mm, from about 5 mm to about 20 mm, or from about 5 mm to about 10 mm.
In some embodiments, the sintered article has a width W of at least 0.5 mm, such as at least 1 mm, such as at least 2 mm, such as at least 5 mm, such as at least 8 mm, such as at least 10 mm, such as at least 15 mm, such as at least 20 mm, such as at least 30 mm, such as at least 50 mm, such as at least 75 mm, such as at least 10 cm, such as at least 15 cm, such as at least 20 cm, and/or no more than 2 m, such as no more than 1 m, such as no more than 50 cm, such as no more than 30 cm. In other embodiments, the sintered article has a different width W.
In one or more embodiments, the sintered article has a thickness (t) in a range from about 3 μm to about 1 mm, from about 4 μm to about 1 mm, from about 5 μm to about 1 mm, from about 6 μm to about 1 mm, from about 7 μm to about 1 mm, from about 8 μm to about 1 mm, from about 9 μm to about 1 mm, from about 10 μm to about 1 mm, from about 11 μm to about 1 mm, from about 12 μm to about 1 mm, from about 13 μm to about 1 mm, from about 14 μm to about 1 mm, from about 15 μm to about 1 mm, from about 20 μm to about 1 mm, from about 25 μm to about 1 mm, from about 30 μm to about 1 mm, from about 35 μm to about 1 mm, from about 40 μm to about 1 mm, from about 45 μm to about 1 mm, from about 50 μm to about 1 mm, from about 100 μm to about 1 mm, from about 200 μm to about 1 mm, from about 300 μm to about 1 mm, from about 400 μm to about 1 mm, from about 500 μm to about 1 mm, from about 3 μm to about 900 μm, from about 3 μm to about 800 μm, from about 3 μm to about 700 μm, from about 3 μm to about 600 μm, from about 3 μm to about 500 μm, from about 3 μm to about 400 μm, from about 3 μm to about 300 μm, from about 3 μm to about 200 μm, from about 3 μm to about 100 μm, from about 3 μm to about 90 μm, from about 3 μm to about 80 μm, from about 3 μm to about 70 μm, from about 3 μm to about 60 μm, from about 3 μm to about 50 μm, from about 3 μm to about 45 μm, from about 3 μm to about 40 μm, from about 3 μm to about 35 μm, from about 3 μm to about 30 μm, or from about 3 μm to about 30 μm.
In some embodiments, the sintered article has a thickness t of at least 3 μm, such as at least 5 μm, such as at least 10 μm, such as at least 15 μm, such as at least 20 μm, such as at least 25 μm, such as at least 0.5 mm, such as at least 1 mm, and/or no more than 5 mm, such as no more than 3 mm, such as no more than 1 mm, such as no more than 500 μm, such as no more than 300 μm, such as no more than 100 μm. In other embodiments, the sintered article has a different thickness t.
In one or more embodiments, the sintered article is continuous and has a length L in a range from about 300 cm to about 500 m, from about 300 cm to about 400 m, from about 300 cm to about 200 m, from about 300 cm to about 100 m, from about 300 cm to about 50 m, from about 300 cm to about 25 m, from about 300 cm to about 20 m, from about 350 cm to about 500 m, from about 400 cm to about 500 m, from about 450 cm to about 500 m, from about 500 cm to about 500 m, from about 550 cm to about 500 m, from about 600 cm to about 500 m, from about 700 cm to about 500 m, from about 800 cm to about 500 m, from about 900 cm to about 500 m, from about 1 m to about 500 m, from about 5 m to about 500 m, from about 10 m to about 500 m, from about 20 m to about 500 m, from about 30 m to about 500 m, from about 40 m to about 500 m, from about 50 m to about 500 m, from about 75 m to about 500 m, from about 100 m to about 500 m, from about 200 m to about 500 m, or from about 250 m to about 500 m.
In some embodiments, the sintered article has a continuous, unbroken length L of at least 5 mm, such as at least 25 mm, such as at least 1 cm, such as at least 15 cm, such as at least 50 cm, such as at least 1 m, such as at least 5 m, such as at least 10 m, and/or no more than 5 km, such as no more than 3 km, such as no more than 1 km, such as no more than 500 m, such as no more than 300 m, such as no more than 100 m. In other embodiments, the sintered article has a different length L. Such continuous long lengths, particularly of materials and qualities disclosed herein, may be surprising to those of skill in the art without technologies disclosed herein, such as the controlled separation, tension control, sintering zones, binder removal techniques, etc.
In one or more embodiments, the body of the sintered article includes a sintered inorganic material. In one or more embodiments, the inorganic material includes an interface having a major interface dimension of less than about 1 mm. As used herein, the term “interface” when used with respect to the inorganic material is defined as including either a chemical inhomogeneity or a crystal structure inhomogeneity or both a chemical inhomogeneity and a crystal structure inhomogeneity.
Exemplary inorganic materials include ceramic materials, glass ceramic materials and the like. In some embodiments, the inorganic material may include any one or more of a piezoelectric material, a thermoelectric material, a pyroelectric material, a variable resistance material, or an optoelectric material. Specific examples of inorganic materials include zirconia (e.g., yttria-stabilized zirconia), alumina, spinel, garnet, lithium lanthanum zirconium oxide (LLZO), cordierite, mullite, perovskite, pyrochlore, silicon carbide, silicon nitride, boron carbide, sodium bismuth titanate, barium titanate, titanium diboride, silicon alumina nitride, aluminum oxynitride, or a reactive cerammed glass-ceramic (a glass ceramic formed by a combination of chemical reaction and devitrification, which includes an in situ reaction between a glass frit and a reactant powder(s)).
In one or more embodiments, the sintered article exhibits compositional uniformity across a specific area. In one or more specific embodiments, the sintered article comprises at least 10 square cm of area along the length that has a composition (i.e., relative amounts of chemicals in weight percent (%)) wherein at least one constituent of the composition varies by less than about 3 weight % (e.g., about 2.5 weight % or less, about 2 weight % or less, about 1.5 weight % or less, about 1 weight % or less, or about 0.5 weight % or less), across that area. For example, when the inorganic material comprises alumina, the amount of aluminum may vary by less than about 3 weight % (e.g., about 2.5 weight % or less, about 2 weight % or less, about 1.5 weight % or less, about 1 weight % or less, or about 0.5 weight % or less), across the at least 10 square cm of area. Such compositional uniformity may be attributed at least in part to new, unique processes, as disclosed herein, such as the furnace heat zones with individually controlled elements, careful and gentle handling of green tape, steady state of the continuous tape processing, etc. In other embodiments, new and inventive tapes or other products of at least some technology disclosed herein may not have such compositional uniformity.
In one or more embodiments, the sintered article exhibits crystalline structure uniformity across a specific area. In one or more specific embodiments, the sintered article includes at least 10 square cm of area along the length that has a crystalline structure with at least one phase having a weight % that varies by less than about 5 percentage points, across that area. For illustration only, the sintered article may include at least one phase that constitutes 20 weight % of the sintered article and the amount of this phase is within the range from about 15 weight % to about 25 weight % across the at least 10 square cm of area. In one or more embodiments, the sintered article includes at least 10 square cm of area along the length that has a crystalline structure with at least one phase having a weight % that varies by less than about 4.5 percentage points, less than about 4 percentage points, less than about 3.5 percentage points, less than about 3 percentage points, less than about 2.5 percentage points, less than about 2 percentage points, less than about 1.5 percentage points, less than about 1 percentage point, or less than about 0.5 percentage points, across that area. Such crystalline structure uniformity may be attributed at least in part to new, unique processes, as disclosed herein, such as the furnace heat zones with individually controlled elements, careful and gentle handling of green tape, steady state of the continuous tape processing, etc. In other embodiments, new and inventive tapes or other products of at least some technology disclosed herein may not have such crystalline structure uniformity.
In one or more embodiments, the sintered article exhibits a porosity uniformity across a specific area. In one or more specific embodiments, the sintered article comprises at least 10 square cm of area along the length that has a porosity varies by less than about 20%. As used herein, the term “porosity” is described as a percent by volume (e.g., at least 10% by volume, or at least 30% by volume), where the “porosity” refers to the portions of the volume of the sintered article unoccupied by the inorganic material. Accordingly, in one example, the sintered article has a porosity of 10% by volume and this porosity is within a range from about greater than 8% by volume to less than about 12% by volume across the at least 10 square cm of area. In one or more specific embodiments, the sintered article comprises at least 10 square cm of area along the length that has a porosity varies by 18% or less, 16% or less, 15% or less, 14% or less, 12% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less or about 2% or less, across that area. Such porosity uniformity may be attributed at least in part to new, unique processes, as disclosed herein, such as the furnace heat zones with individually controlled elements, careful and gentle handling of green tape, steady state of the continuous tape processing, etc. In other embodiments, new and inventive tapes or other products of at least some technology disclosed herein may not have such porosity uniformity.
In one or more embodiments, the sintered article exhibits a granular profile, such as when viewed under a microscope, as shown in the digital image of
The granular profile is or may be an indicator of the process of manufacturing used to form the sintered article 1000. In particular, the granular profile is or may be an indicator that the article 1000 was sintered as a thin continuous article (i.e., as a sheet or tape), as opposed to being cut from a boule, and that the respective surface 1010, 1020 has not been substantially polished. Additionally, compared to polished surfaces, the granular profile may provide benefits to the sintered article 1000 in some applications, such as scattering light for a backlight unit of a display, increasing surface area for greater adhesion of a coating or for culture growth. In contemplated embodiments, the surfaces 1010, 1020 have a roughness from about 10 nm to about 1000 nm across a distance of 10 mm in one dimension along the length of the sintered article, such as from about 15 nm to about 800 nm. In contemplated embodiments, either or both of the surfaces 1010, 1020 have a roughness of from about 1 nm to about 10 μm over a distance of 1 cm along a single axis.
In one or more embodiments, the one or both surfaces 1010, 1020 may be polished, where grain boundary grooves and grain asperities (or hillocks) are generally removed due to the polishing. In contemplated embodiments, sintered articles 1000 manufactured according to the processes disclosed herein may be polished, with a surface similar to that shown in
Without being bound by theory, it is believed that sheets of sintered ceramic or other materials cut from boules may not have readily identifiable grain boundaries present on surfaces thereon, in contrast to the article of
In some embodiments, such as where the sintered article 1000 is in the form of a sheet or tape, the surface consistency is such that either one or both of the first and second surfaces 1010, 1020 have few surface defects. In this context, surface defects are abrasions and/or adhesions having a dimension along the respective surface of at least 15 μm, 10 μm, and/or 5 μm. In one or more embodiments, one or both the first major surface 1010 and second major surface 1020 have fewer than 15, 10, and/or 5 surface defects having a dimension greater than 15 μm, 10 μm, and/or 5 μm per square centimeter. In one example, one or both the first major surface 1010 and second major surface 1020 have fewer than 3 or fewer than 1 such surface defects on average per square centimeter. In one or more embodiments, one of or both the first major surface and the second major surface have at least ten square centimeters of area having fewer than one hundred surface defects from adhesion or abrasion with a dimension greater than 5 μm. Alternatively or additionally, one of the first and major surface has at least ten square centimeters of area having fewer than one hundred surface defects from adhesion or abrasion with a dimension greater than 5 μm, while the other of the first major surface and the second major surface comprises surface defects from adhesion or abrasions with a dimension of greater than 5 μm. Accordingly, sintered articles manufactured according to inventive technologies disclosed herein may have relatively high and consistent surface quality. Applicant believes that the high and consistent surface quality of the sintered article 1000 facilitates increased strength of the article 1000 by reducing sites for stress concentrations and/or crack initiations.
The sintered article may be described as having a flatness in a range from about 0.1 μm (100 nm) to about 50 μm over a distance of 1 cm along a single axis (e.g., such as along the length or the width of the sintered article). In some embodiments, the flatness may be in a range from about 0.2 μm to about 50 μm, from about 0.4 μm to about 50 μm, from about 0.5 μm to about 50 μm, from about 0.6 μm to about 50 μm, from about 0.8 μm to about 50 μm, from about 1 μm to about 50 μm, from about 2 μm to about 50 μm, from about 5 μm to about 50 μm, from about 10 μm to about 50 μm, from about 20 μm to about 50 μm, from about 25 μm to about 50 μm, from about 30 μm to about 50 μm, from about 0.1 μm to about 45 μm, from about 0.1 μm to about 40 μm, from about 0.1 μm to about 35 μm, from about 0.1 μm to about 30 μm, from about 0.1 μm to about 25 μm, from about 0.1 μm to about 20 μm, from about 0.1 μm to about 15 μm, from about 0.1 μm to about 10 μm, from about 0.1 μm to about 5 μm, or from about 0.1 μm to about 1 μm. Such flatness, in combination with the surface quality, surface consistency, large area, thin thickness, and/or material properties of materials disclosed herein, may allow sheets, substrates, sintered tapes, articles, etc. to be particularly useful for various applications, such as tough cover sheets for displays, high-temperature substrates, flexible separators, and other applications. With that said, embodiments may not have such flatness. Flatness is measured with a respective national standard (e.g. ASTM A1030).
In one or more embodiments, the sintered article exhibits a striated profile along the width dimension as shown in
In one or more embodiments, the sintered article may be planar. In one or more embodiments, a portion of the sintered article or a discrete sintered article (as will be described herein) may have a have a three-dimensional shape. For example, in one or more embodiments, a portion of the sintered article or a discrete sintered article may have a saddle shape (which has a convex shape along the width and a concave shape along the length, or a concave shape along the width and a convex shape along the length). In one or more embodiments, a portion of the sintered article or a discrete sintered article may have a c-shape (which has a single concave shape along the length). In one or more embodiments, the shape magnitude (which means the maximum height of the portion of the sintered article or a discrete sintered article measured from the plane on which it is disposed) is less than about 0.75 mm (e.g., about 0.7 mm or less, 0.65 mm or less, 0.6 mm or less, 0.55 mm or less, 0.5 mm or less, 0.45 mm or less, 0.4 mm or less, 0.35 mm or less, 0.3 mm or less, 0.25 mm or less, 0.2 mm or less, 0.15 mm or less, or 0.1 mm or less).
According to another aspect, the embodiments of the sintered article may be described in terms of flattenability or being flattenable in standard, room temperature (at 23° C.) conditions, without heating the sintered article near melting or sintering temperature to soften the article for flattening. In some embodiments, a portion of the sintered article is flattenable. A portion of the sintered article that is flattenable may have a length of about 10 cm or less. In some embodiments, the sintered article may have dimensions otherwise described herein (e.g., width is about 5 mm or greater, the thickness is in a range from about 3 μm to about 1 mm, and the length is about 300 cm or greater), with the portion of the sintered article that is flattenable having a length of 10 cm or less. In some embodiments, for instance where the sintered article is a discrete sintered article, the entire sintered article is flattenable.
As used herein, flattenability is determined by flattening the sintered article by pinching the sintered article (or portion of the sintered article) between two rigid parallel surfaces, or by applying surface pressure on a first major surface 1010 of the sintered article (or portion of the sintered article) against a rigid surface to flatten the sintered article (or portion of the sintered article) along a planar flattening plane. The measure of flattenability may be expressed as the force required to pinch the sintered article (or portion of the sintered article) flat to within a distance of 0.05 mm, 0.01 mm or 0.001 mm from the flattening plane, when the sintered article (or portion of the sintered article) is pinched between two rigid parallel surfaces. The measure of flattenability may alternatively be expressed as the surface pressure applied to a first major surface 1010 to push the sintered article (or portion of the sintered article) flat to within a distance of 0.001 mm from the flattening plane, when the sintered article (or portion of the sintered article) is pushed against a rigid surface. The measure of flattenability may be expressed as the absolute maximum in plane surface stress (compressive or tensile) on the sintered article (or portion of the sintered article) when the sintered article (or portion of the sintered article) is flattened to within a distance of 0.05 mm, 0.01 mm or 0.001 mm from the flattening plane using either flattening method (i.e., pinching between two rigid parallel surfaces or against a rigid surface). This stress may be determined using the thin plate bend bending equation, σx=Et/2R(1−ν2).
The thin plate bend stress equation is derived from the equation σx=[E/(1−ν2)]·(εx+νεy), where E is elastic modulus, ν is Poisson's ratio and εx and εy are strain in the respective directions. With a thick beam, where deflection is much less than the beam thickness, εx is proportional to thickness squared. However, when the beam thickness is significantly less than the bend radius (e.g., the sintered article may have a thickness t of about 20 μm and is bent to a bend radius of a millimeter magnitude), εy=0 is applicable. As illustrated in
In one or more embodiments, the sintered article or the portion of the sintered article, when flattened at least to magnitudes described above, exhibits a maximum in plane stress (which is defined as the maximum absolute value of stress regardless of whether it is compressive stress or tensile stress, as determined by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (which is measured by 2-point bend strength) of the sintered article. For example, the maximum in plane stress of the sintered article or the portion of the sintered article may be less than or equal to 24%, less than or equal to 22%, less than or equal to 20%, less than or equal to 18%, less than or equal to 16%, less than or equal to 15%, less than or equal to 14%, less than or equal to 12%, less than or equal to 10%, less than or equal to 5%, or less than or equal to 4%, of the bend strength of the sintered article.
In one or more embodiments, the sintered article or a portion of the sintered article is flattenable such that the sintered article or portion of the sintered article exhibits a maximum in plane stress of less than or equal to 1% of the Young's modulus of the sintered article, when flattened as described herein. In one or more embodiments, the maximum in plane stress of the sintered article may be less than or equal to 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1% or 0.05% of the Young's modulus of the sintered article.
In one or more embodiments, the sintered article or a portion of the sintered article is flattenable such that when the sintered article or the portion of the sintered article has a thickness in a range from about 40 μm to about 80 μm (or other thicknesses disclosed herein) and is bent to a bend radius of greater than 0.03 m, the sintered article or portion hereof exhibits a maximum in plane stress of less than or equal to 25% of the bend strength of the article. In one or more embodiments, the sintered article or a portion of the sintered article is flattenable such that when the sintered article or the portion of the sintered article has a thickness in a range from about 20 μm to about 40 μm (or other thicknesses disclosed herein) and is bent to a bend radius of greater than 0.015 m, the sintered article or a portion of the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article. In one or more embodiments, when the sintered article has a thickness in a range from about 3 μm to about 20 μm (or other thicknesses disclosed herein) and is bent to a bend radius of greater than 0.0075 m, the sintered article or a portion of the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article.
In one or more embodiments, the sintered article or a portion of the sintered article is flattenable such that when the sintered article or the portion of the sintered article has a thickness of about 80 μm (or other thicknesses disclosed herein) and is bent to a bend radius of greater than 0.03 m, the sintered article or portion hereof exhibits a maximum in plane stress of less than or equal to 25% of the bend strength of the article. In one or more embodiments, the sintered article or a portion of the sintered article is flattenable such that when the sintered article or the portion of the sintered article has a thickness of about 40 μm (or other thicknesses disclosed herein) and is bent to a bend radius of greater than 0.015 m, the sintered article or a portion of the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article. In one or more embodiments, when the sintered article has a thickness of about 20 μm (or other thicknesses disclosed herein) and is bent to a bend radius of greater than 0.0075 m, the sintered article or a portion of the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article.
In one or more embodiments, the sintered article or a portion thereof is flattenable such that the sintered article or a portion thereof exhibits a maximum in plane stress of less than 250 MPa when flattened to within a distance of 0.05 mm, 0.010 mm or 0.001 mm from the flattening plane using either flattening method (i.e., pinching between two rigid parallel surfaces or against a rigid surface). In one or more embodiments, the maximum in plane stress may be about 225 MPa or less, 200 MPa or less, 175 MPa or less, 150 MPa or less, 125 MPa or less, 100 MPa or less, 75 MPa or less, 50 MPa or less, 25 MPa or less, 15 MPa, 14 MPa or less, 13 MPa or less, 12 MPa or less, 11 MPa or less, 10 MPa or less, 9 MPa or less, 8 MPa or less, 7 MPa or less, 6 MPa or less, 5 MPa or less, or 4 MPa or less.
In one or embodiments, the sintered article or a portion thereof is flattenable such that a force of less than 8 N (or 7 N or less, 6 N or less, 5 N or less, 4 N or less, 3 N or less, 2 N or less, 1 N or less, 0.5 N or less, 0.25 N or less, 0.1 N or less, or 0.05 N or less) is required to flatten the sintered article or a portion thereof within a distance of 0.05 mm, 0.010 mm or 0.001 mm from the flattening by pinching between two rigid parallel surfaces.
In one or more embodiments, the sintered article or a portion thereof is flattenable such that a pressure of 0.1 MPa or less is required to push the sintered article (or portion of the sintered article) flat to within a distance of 0.05 mm, 0.010 mm or 0.001 mm from the flattening plane, when the sintered article (or portion of the sintered article) is pushed against a rigid surface. In some embodiments, the pressure may be about 0.08 MPa or less, about 0.06 MPa or less, about 0.05 MPa or less, about 0.04 MPa or less, about 0.02 MPa or less, about 0.01 MPa or less, about 0.008 MPa or less, about 0.006 MPa or less, about 0.005 MPa or less, about 0.004 MPa or less, about 0.002 MPa or less, about 0.001 MPa or less, or 0.0005 MPa or less.
According to another aspect, the sintered article may be a sintered tape material that is rolled into a rolled sintered article as shown in
In one or more embodiments, the sintered article wound around the core is continuous and has the dimensions otherwise described herein (e.g., a width that is about 5 mm or greater, a thickness in a range from about 3 μm to about 1 mm, and a length is about 30 cm or greater).
Spooling of a continuous sintered article (and in particular, a continuous sintered inorganic material such as ceramics) onto a core presents several challenges because the sintered article has cross web shape, and web tensions that the sintered article can tolerate, particularly in the binder burn out and bisque states, are extremely low (e.g., tensions of gram level magnitude). Furthermore, the modulus of the sintered material can be very high (e.g., up to and including about 210 GPa) and therefore, the sintered article does not stretch under tension and, when wound around a core, the resulting wound roll integrity may be poor. During handling the successive convolutions, a continuous sintered article can easily telescope (i.e., the successive wraps can move out of alignment).
Applicants have found that rolled sintered article of one or more embodiments has superior integrity by using a compliant interlayer support material when spooling the continuous sintered article onto a core. In one or more embodiments, the continuous sintered article is disposed on an interlayer support material and the continuous sintered article and interlayer support material are wound around the core such that each successive wrap of the continuous sintered article is separated from one another by the interlayer support material. As described above with reference to
Referring to
In one or more embodiments, the interlayer support material 46 comprises a tension (or is under a tension) that is greater than a tension on the continuous sintered article, as measured by a load cell. In one or more embodiments, the interlayer support material has a relatively low modulus (compared to the sintered article) and thus is stretched under low tension. It is believed that this creates higher interlayer roll pressures that improve the wound roll integrity. Furthermore, the tension in the wound roll in some embodiments is controlled by controlling the tension applied to the interlayer support material and that tension can be tapered as a function of wound roll diameter. In some such embodiments, the interlayer support material 46 is in tension, while the sintered article (e.g., tape) is in compression.
In one or more embodiments, the interlayer support material is thickness compliant (i.e., the thickness can be decreased by applying pressure to a major surface and can therefore compensate for variation in the cross web shape or thickness in the sintered article generated by the sintering process). In some such embodiments, when viewed from the side, the sintered article may be hidden within the roll by the interlayer support material, where the interlayer support material contacts adjoining winds of interlayer support material and, at least to some degree, shields and isolates the sintered article, such as where the interlayer support material is wider than the sintered article as shown in
Referring to
In one or more embodiments, the rolled article comprises a frictional force between the interlayer support material and the continuous or non-continuous sintered article that is sufficient to resist lateral telescoping of the successive convolutions in the wound roll, even when very low tension is applied to the interlayer support material. A constant tension may be applied to the interlayer support material; however, the tension applied to the interior portions of the rolled article toward the core may be greater than the tension applied to exterior portions of the rolled article away from the core due to the diameter of the rolled article increasing from the core to the exterior portions as more interlayer support material and continuous sintered article is wound around the core. This compresses or may compress the rolled article, which, when coupled with the friction between the interlayer support material and the continuous sintered article, prevents or limits telescoping and relative movement between sintered article surfaces to at least help prevent defects.
In one or more embodiments, the interlayer support material comprises any one of or both a polymer and a paper. In some embodiments, the interlayer support material is a combination of polymer and paper. In one or more embodiments, the interlayer support material may include a foamed polymer. In some embodiments, the foamed polymer is closed cell.
According to another aspect, the sintered articles described herein may be provided as a plurality of discrete sintered articles, as disclosed above, as illustrated in
In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable, as described herein. In one or more embodiments, some, most, or each of the plurality of sintered articles, when flattened, exhibits a maximum in plane stress (which is defined as the maximum absolute value of stress regardless of whether it is compressive stress or tensile stress, as determined by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (which is measured by 2-point bend methods) of the sintered article. For example, the maximum in plane stress of some, most, or each of the plurality of sintered articles may be less than or equal to 24%, less than or equal to 22%, less than or equal to 20%, less than or equal to 18%, less than or equal to 16%, less than or equal to 15%, less than or equal to 14%, less than or equal to 12%, less than or equal to 10%, less than or equal to 5%, or less than or equal to 4%, of the bend strength of the sintered article.
In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that some, most, or each of the plurality of sintered articles exhibits a maximum in plane stress of less than or equal to 1% of the Young's modulus of the sintered article, when flattened as described herein. In one or more embodiments, the maximum in plane stress of some, most, or each of the plurality of sintered articles may be less than or equal to 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1% or 0.05% of the Young's modulus of the respective sintered article.
In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that when the sintered article has a thickness in a range from about 40 μm about 80 μm (or other thickness disclosed herein) and is bent to a bend radius of greater than 0.03 m, the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength of the article. In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that when the sintered article has a thickness in a range from about 20 μm to about 40 μm (or other thickness disclosed herein) and is bent to a bend radius of greater than 0.015 m, the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article. In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that when the sintered article has a thickness in a range from about 3 μm to about 20 μm (or other thickness disclosed herein) and is bent to a bend radius of greater than 0.0075 m, the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article.
In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that when the sintered article has a thickness of about 80 μm (or other thickness disclosed herein) and is bent to a bend radius of greater than 0.03 m, the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength of the article. In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that when the sintered article has a thickness of about 40 μm (or other thickness disclosed herein) and is bent to a bend radius of greater than 0.015 m, the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article. In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that when the sintered article has a thickness of about 20 μm (or other thickness disclosed herein) and is bent to a bend radius of greater than 0.0075 m, the sintered article exhibits a maximum in plane stress of less than or equal to 25% of the bend strength (as measured by 2-point bend strength) of the article.
In one or more embodiments, some, most, or each of the plurality of sintered articles is flattenable such that the sintered article exhibits a maximum in plane stress of less than 250 MPa when flattened to within a distance of 0.05 mm, 0.01 mm, or 0.001 mm from the flattening plane using either flattening method (i.e., pinching between two rigid parallel surfaces or against a rigid surface). In one or more embodiments, the maximum in plane stress may be about 225 MPa or less, 200 MPa or less, 175 MPa or less, 150 MPa or less, 125 MPa or less, 100 MPa or less, 75 MPa or less, 50 MPa or less, 25 MPa or less, 15 MPa, 14 MPa or less, 13 MPa or less, 12 MPa or less, 11 MPa or less, 10 MPa or less, 9 MPa or less, 8 MPa or less, 7 MPa or less, 6 MPa or less, 5 MPa or less, or 4 MPa or less.
In one or embodiments, some, most, or each of the plurality of sintered articles is flattenable such that a force of less than 8 N (or 7 N or less, 6 N or less, 5 N or less, 4 N or less, 3 N or less, 2 N or less, 1 N or less, 0.5 N or less, 0.25 N or less, 0.1 N or less, or 0.05 N or less) is required to flatten the sintered article or a portion thereof, respectively, when the sintered article is flattened to within a distance of 0.05 mm, 0.01 mm, or 0.001 mm from the flattening by pinching between two rigid parallel surfaces.
In one or embodiments, some, most, or each of the plurality of sintered articles is flattenable such that a pressure of 0.1 MPa or less is required to push the sintered article flat to within a distance of 0.05 mm, 0.01 mm, or 0.001 mm from the flattening plane, when pushed against a rigid surface. In some embodiments, the pressure may be about 0.08 MPa or less, about 0.06 MPa or less, about 0.05 MPa or less, about 0.04 MPa or less, about 0.02 MPa or less, about 0.01 MPa or less, about 0.008 MPa or less, about 0.006 MPa or less, about 0.005 MPa or less, about 0.004 MPa or less, about 0.002 MPa or less, about 0.001 MPa or less, or 0.0005 MPa or less.
In one or more embodiments, the thickness of some, most, or each of the plurality of sintered articles is within a range from about 0.7 t to about 1.3 t (e.g., from about 0.8 t to about 1.3 t, from about 0.9 t to about 1.3 t, from about t to about 1.3 t, from about 1.1 t to about 1.3 t, from about 0.7 t to about 1.2 t, from about 0.7 t to about 1.1 t, from about 0.7 t to about it, or from about 0.9 t to about 1. It), where t is the thickness values disclosed herein.
In one or more embodiments, some, most, or each of the plurality of sintered article exhibits compositional uniformity. In one or more embodiments, at least 50% (e.g., about 55% or more, about 60% or more, or about 75% or more) of the plurality of sintered articles comprise an area and a composition, wherein at least one constituent of the composition (as described herein) varies by less than about 3 weight % across the area. In some embodiments, at least one constituent of the composition varies by about 2.5 weight % or less, about 2 weight % or less, about 1.5 weight % or less, about 1 weight % or less, or about 0.5 weight % or less), across that area. In one or more embodiments, the area is about 1 square centimeter of the sintered article, or the area is the entire surface area of the sintered articles.
In one or more embodiments, some, most, or each of the plurality of sintered article exhibits crystalline structure uniformity. In one or more embodiments, at least 50% (e.g., about 55% or more, about 60% or more, or about 75% or more) of the plurality of sintered articles comprise an area and a crystalline structure with at least one phase having a weight percent that varies by less than about 5 percentage points (as described herein) across the area. For illustration only, some, most, or each of the plurality of sintered article may include at least one phase that constitutes 20 weight % of the sintered article and, in at least 50% (e.g., about 55% or more, about 60% or more, or about 75% or more) of the plurality of sintered articles, this phase is present in an amount in a range from about 15 weight % to about 25 weight % across the area. In one or more embodiments, at least 50% (e.g., about 55% or more, about 60% or more, or about 75% or more) of some, most, or each of the plurality of sintered articles comprise an area and a crystalline structure with at least one phase having a weight percent that varies by less than about 4.5 percentage points, less than about 4 percentage points, less than about 3.5 percentage points, less than about 3 percentage points, less than about 2.5 percentage points, less than about 2 percentage points, less than about 1.5 percentage points, less than about 1 percentage point, or less than about 0.5 percentage points, across that area. In one or more embodiments, the area is about 1 square centimeter of the sintered article, or the area is the entire surface area of the sintered articles.
In one or more embodiments, at least 50% (e.g., about 55% or more, about 60% or more, or about 75% or more) of the plurality of sintered article comprise an area and a porosity (as described herein) that varies by less than about 20%. Accordingly, in one example, some, most, or each of the plurality of sintered articles has a porosity of 10% by volume and this porosity is within a range from about greater than 8% by volume to less than about 12% by volume across the area in at least 50% of the plurality of sintered articles. In one or more specific embodiments, at least 50% of the plurality of sintered articles comprises an area and has a porosity that varies by 18% or less, 16% or less, 15% or less, 14% or less, 12% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less or about 2% or less across the area. In one or more embodiments, the area is about 1 square centimeter of the sintered article, or the area is the entire surface area of the sintered article.
Examples 5-6 and Comparative Examples 7-8Examples 5-6 and Comparative Examples 7-8 are discrete sintered articles formed from a continuous sintered article of tetragonal or tetra zirconia polycrystalline material. Examples 5-6 were formed according to the process and system described herein and Comparative Examples 7-8 were formed using other processes and systems that do not include at least some of the presently disclosed technology (e.g., tension control, zoned sintering furnace, air flow control). Each of Examples 5-6 and Comparative Examples 7-8 had length of 55.88 mm, a width of 25.4 mm, a thickness of 0.04 mm, and a corner radius of 2 mm. Each of Examples 5-6 and Comparative Examples 7-8 had a Young's modulus of 210 GPa, Poisson's ratio (ν) of 0.32, and a density (ρ) of 6 g/cm3.
Example 5 had a c-shape as shown in
The flattenability of the Examples was evaluated using the two loading methods otherwise described herein (i.e., pinching the sintered articles between two rigid parallel surfaces or applying a surface pressure on one major surface of the sintered article to push the sintered article against a rigid surface, to flatten the sintered article along a flattening plane).
In some semiconductor packages and similar light emitting diode (LED) containing packages, much of the electrical energy provided to or through the package may be lost or dissipated as heat energy. The heat dissipation capacity of these and similar semiconductor packages may be a limiting factor when trying to provide additional electrical energy (or current) through the package. Also, in at least some LED containing packages, brightness of the LED may be limited by the heat dissipation capacity of the LED containing package. It may be desirable to reduce and maintain the temperature of the components in a semiconductor package, such as from about 75° C. to about 85° C.
In one or more embodiments and referring to
In some embodiments, package 2000 includes an interlayer 1300 between substrate 1500 and sintered article 1000. Interlayer 1300 may include a material that joins, bonds, connects, or otherwise attaches or facilitates attachment of substrate 1500 and sintered article 1000. Interlayer 1300 may include a plurality of discrete layers joined or joined together to form interlayer 1300. In some embodiments, interlayer 1300 is a material with high thermal conductivity properties such that heat generated by electrical components (e.g., a semiconductor device or chip) or metal-based layers is conducted through interlayer 1300 to substrate 1500. In some embodiments, interlayer 1300 includes a thermal conductivity greater than that of sintered article 1000. In some embodiments, interlayer 1300 includes a thermal conductivity less than substrate 1500. Interlayer 1300 may have a thermal conductivity greater than about 8 W/m K to about 20 W/m K, greater than about 8 W/m K to about 16 W/m K, or greater than about 8 W/m K to about 13 W/m K, or greater than about 9 W/m K to about 12 W/m K, such as 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 W/m K, including all ranges and subranges therebetween. In some embodiments, interlayer 1300 is an adhesive-like material. In some embodiments, interlayer 1300 is a compliant material which is configured to deform and/or to withstand shearing forces from coefficient of thermal expansion (CTE) differences between substrate 1500 and sintered article 1000 which occur as a result of heating and cooling of package 2000.
In some embodiments, interlayer 1300 includes a matrix of a polyimide, an epoxy, or combinations thereof. In some embodiments, the matrix of interlayer 130 may include nonconductive particles (e.g., boron nitride), conductive particles (e.g., silver, copper, etc.), or combinations thereof. The conductive and/or non-conductive particles may be homogeneously or non-homogeneously distributed throughout the matrix of interlayer 130. In some embodiments, interlayer 1300 conducts heat from metal-based layer 1350 and components 1401 (
In one or more embodiments, substrate 1500 includes a first major surface 1510, a second major surface 1520 opposing the first major surface, and a body 1530 extending between the first and second surfaces 1510, 1520. Sintered article 1000 may be directly or indirectly joined, bonded, connected, or otherwise attached to first major surface 1510 or second major surface 1520 of substrate 1500. The body 1530 has a thickness (t1) defined as a distance between the first major surface 1510 and the second major surface 1520, a width (W1) defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width. In one or more embodiments, substrate 1500 includes opposing minor surfaces 1540 that define the width W1. In some embodiments, the lengths and widths of sintered article 1000 and substrate 1500, respectively, are substantially equivalent (e.g., the lateral dimensions within 5% of each other). In some embodiments, the thickness (t1) of substrate 1500 is greater than the thickness (t) of sintered article 1000, such as the thicknesses (t) disclosed herein for sintered article 1000. In some embodiments, the thickness (t1) of substrate 1500 is about 25% greater than, about 50% greater than, about 75% greater than, about 100% greater than, about 200% greater than, about 500% greater than or more than the thickness (t) of sintered article 1000. In some embodiments, the thickness (t1) of substrate 1500 is from about 0.5 mm to about 5.0 mm, or from about 1.0 mm to about 2.0 mm, or from about 1.0 mm to about 1.6 mm, or even from about 1.2 mm to about 1.5 mm. In some embodiments, substrate 1500 acts as a heat sink for package 2000. In some embodiments, substrate 1500 comprises an electrically conductive metal, such as aluminum, copper, or combinations thereof.
As illustrated in
Metal-based layer 1350 may be directly or indirectly joined to sintered article 1000 by electroplating, printing, physical vapor deposition, chemical vapor deposition, sputtering, or other similar techniques. Metal-based layer 1350 is an electrically conductive material capable of conducting or providing electrical energy (or current) across and through package 2000. In some embodiments, metal-based layer is configured to minimize electrical resistance and heat generation across its length. In some embodiments, metal-based layer 1350 comprises copper, nickel, gold, silver, gold, brass, lead, tin, and combinations thereof. Metal-based layer 1350 may be indirectly joined to sintered article 1000 via a seed layer 1375. That is, seed layer 1375 may provide a foundation for joining metal-based layer 1350 to sintered article 1000. In some embodiments, seed layer 1375 that joins metal-based layer 1350 to sintered article 1000 is “reflowed” in a reflow oven to electrically connect the metal-based layer 1350 to other electrical components in the package 2000. In some embodiments, seed layer 1375 comprises tin, titanium, tungsten, lead, or combinations thereof. Seed layer 1375 may be applied to a major surface of sintered article 1000 by electroplating, printing, physical vapor deposition, chemical vapor deposition, sputtering, or other similar techniques.
In some embodiments, metal-based layer 1350 may be directly or indirectly joined to sintered article 1000 before, during, or after sintered article 1000 is joined to substrate 1500. In some embodiments, metal-based layer 1350 is a continuous, semi-continuous, or discontinuous array or “circuit” on a major surface of sintered article 1000. In some embodiments, prior to applying metal-based layer 1350 and/or seed layer 1375 on sintered article 1000, portions of one or both major surfaces of sintered article 1000 may be masked or covered to prevent application of metal-based layer 1350 and/or seed layer 1375 on said masked portions of sintered article 1000. That is, the masking portions of one or both major surfaces of sintered article 1000 may be used to form a semi-continuous or discontinuous array or “circuit” of metal-based layer 1350 and/or seed layer 1375 on a major surface of sintered article 1000. After metal-based layer 1350 is applied to an unmasked portion of a major surface of sintered article 1000, masking may be removed to expose that portion of the major surface (without a metal based layer and/or seed layer thereon) where the masking was present.
In one or more embodiments, package 2000 includes a semiconductor device or chip 1400. In some embodiments, semiconductor device 1400 is directly or indirectly joined, bonded, connected, or otherwise attached to first major surface 1010 or second major surface 1020 of substrate 1000. Semiconductor device 1400 may be indirectly joined to sintered article 1000 via seed layer 1375 as shown in
In one or more embodiments, methods of making package 2000 include providing sintered article 1000. Sintered article 1000 may be in on a roll including a round or cylindrical core having a diameter of less than 60 cm, the continuous sintered article wound around the core. Sintered article 1000 may also be provided as discrete flattened lengths. In one or more embodiments, methods of making package 2000 include providing a carrier or temporary substrate 1499 (
In some embodiments, precursor package 1999 includes a precursor interlayer 1299 (
The total light transmitted (T) through the sintered article 1000 may be defined by the follow equation 1:
T=Φet/Φei (1)
where,
Φet is the radiant flux transmitted by that surface; and
Φei is the radiant flux received by that surface.
The measurement of these quantities is described in ASTM standard test method D1003-13.
Although similar to
In one or more embodiments, the sintered articles described herein may be used in microelectronics applications or articles. For example, such microelectronics articles may include a sintered article (according to one or more embodiments described herein) including a first major surface, a second major surface opposing the first major surface. In one or more embodiments, the microelectronics article may include a continuous (e.g., long tape, as described herein) or discrete (e.g., sheets cut or singulated from a tape) sintered article. In one or more embodiments, the microelectronics article includes a continuous or discrete sintered article having a width of about 1 mm or greater, about 1 cm or greater, about 5 cm or greater, or about 10 cm or greater. In one or more embodiments, the microelectronics article includes a sintered article having a length of about 1 m or greater, 5 m or greater, or about 10 m or greater. In one or more embodiments, the microelectronics article includes a continuous or discrete sintered article having a thickness of less than 1 mm, about 0.5 mm or less, about 300 micrometers or less, about 150 micrometers or less, or about 100 micrometers or less. In one or more embodiments of a microelectronic article includes a sintered article having a crystalline ceramic content by volume of about 10% or greater, about 25% or greater, 50% or greater, about 75% or greater, or about 90% or greater.
In one or more embodiments, the sintered article includes one or more vias (e.g., holes, apertures, wells, pipes, passages, linkages; see hole 1490 of
In one or more embodiments, the sintered article includes a conductive layer (e.g., copper, aluminum, or other conductive layer; see generally layer 1350 of
In some embodiments, the sintered article may include two or more of a plurality of vias, a conductive layer and one or more additional layers.
In one or more embodiments, system 10 for producing a sintered tape article may include a fabrication system for further processing a green tape, partially sintered articles, and/or sintered articles described herein for use in a microelectronics article. In one or more embodiments, the fabrication system may be disposed downstream of the binder burn out furnace 110 but upstream of the sintering station 38 to process tape without binder, or after the sintering station 38 to process a partially sintered article or before the furnace 110 to process the green tape, which would then be sintered as otherwise described herein. In one or more embodiments, the fabrication system may be disposed downstream of the sintering station 38 but upstream of the uptake system 42 to process a sintered article. In one or more embodiments, the fabrication system may be disposed downstream of the uptake reel 44 but upstream of the reel 48, to process a sintered article. In one or more embodiments, the fabrication system may be disposed downstream from the reel 48 to process a sintered article. In such embodiments, the fabrication system would process the green tape material, partially sintered article or sintered article when it is continuous (and not discrete). Other configurations are possible to process the sintered article as a discrete article.
In one or more embodiments, the fabrication system may expose at least a portion of the green tape material, partially sintered article or sintered article to a mechanism for forming vias, such as laser energy, or a drill. The fabrication system of one or more embodiments using laser energy to create the vias may include a hug drum (see generally vacuum drum 25 of
In one or more embodiments, the vias may be created by mechanical means. For example, the fabrication system may include a flat plate on which a portion of the green tape material, partially sintered article or sintered article is temporarily secured. In this manner, one major surface of the green tape material, partially sintered article or sintered article is in contact with the flat plate. The conveyance of the green tape material, partially sintered article or sintered article to the fabrication system may use a step and repeat motion, acceleration or deceleration velocity, or continuous velocity to allow for a portion of the sintered article to be temporarily secured to the flat plate. In one or more embodiments, a vacuum may be used to temporarily secure a portion of the green tape material, partially sintered article or sintered article to the flat plate.
In one or more embodiments, fabrication system may form vias by mechanically separating a portion of the green tape material, partially sintered article or sintered article. In one or more embodiments, the fabrication system may include the use of photolithography, with solvents or acids to remove a portion of the green tape material, partially sintered article or sintered article. In such embodiments, when the fabrication system is applied to green tape material or partially sintered articles, the fabrication system may include a control mechanism for controlling the scale and pattern scale of the vias, due to shrinkage of the green tape material or partially sintered article when it is fully sintered. For example, the control mechanism may include a sensor at the outlet of the sintering station 38 that measures the distance between the vias and the spacing of the vias and feedback this information to the fabrication system for adjustment. For example, if the fabrication system was forming vias having a diameter of about 75 micrometers, and a distance or pitch of 500 micrometers between the vias, and it was assumed that the full sintering shrinkage from the green tape material to the sintered article was 25%, then the fabrication system would or may adjust to form the vias in the green tape material to have a pitch of 667 microns and a diameter of about 100 micrometers. After processing, the full sintering shrinkage is measured to be 23% then, the fabrication system could further adjust to the correct spacing for the vias in the green tape material would be 649 microns, to accommodate for 23% full sintering shrinkage. Vias in some embodiments have a widest cross-sectional dimension (coplanar with a surface of the sheet or tape) that is at least 250 nm, such as at least 1 μm, such as at least 10 μm, such as at least 30 μm, such as at least 50 μm, and/or no more than 1 mm, such as no more than 500 μm, such as no more than 100 μm. In some embodiments, the vias are filled with an electrically conductive material, such as copper, gold, aluminum, silver, alloys thereof, or other materials. The vias may be laser cut, laser and etchant formed, mechanically drilled, or otherwise formed. The vias may be arranged in a repeating pattern along a sheet or tape, which may later be singulated into individual electronics components.
The system 10 described herein provides other ways to control via spacing during the sintering process. For example, tension in the processing direction 14 during sintering can stretch the sintering article and bias the sintering shrinkage. This tension can increase the spacing of the vias in the processing direction 14, effectively reducing the sintering shrinkage in the processing direction 14. Differential sintering in the processing direction 14 as opposed to the direction perpendicular to the processing direction 14 has been observed, and can be in a range from about 2% to about 3%, when tension is applied. Accordingly, some otherwise round vias may be oval or oblong.
The size and shape of the vias can be controlled and adjusted with a combination of the sintering shrinkage along the direction parallel to the processing direction 14, sintering shrinkage across the direction perpendicular to the processing direction 14, tension in the two directions and the shape of the sintering station 38 and/or through use of air bearings to transport the green tape material, the partially sintered article or the sintered article while sintering or hot.
In one or more embodiments, ceramic material may be added at any step within the system 10 to decrease the sintering shrinkage. Ceramic material can be added by ink jet print heads, which can apply such ceramic material uniformly to a porous partially sintered article or sintered article, while such articles have open porosity. In one or more embodiments, small amounts of ceramic material can be added to the porous partially sintered article or sintered article by printing. Lasers, photolithography, ink jets, atomic layer deposition, and some printing and other processing means can be accomplished from the inner radius of a curved air bearing or with a sectioned hug drum with open areas for the exposure of the partially sintered article or sintered article to the processing equipment. Accordingly, tape or other articles as disclosed herein may be or include a portion thereof of two or more co-fired inorganic materials (e.g., ceramics or phases), such as where one of the materials infiltrates and fills pores of the other material. In contemplated embodiments, the filling/infiltrating material may be chemically the same as the porous material, but may be distinguishable in terms of crystal content (e.g., grain size, phase).
In one or embodiments, vias can be formed on sintered article having with patterns of conductor layers on one or both sides. The conductor layer(s) can be printed or patterned (screen printing, electroless deposition, etc.) after via formation and final sintering. In one or more embodiments, the conductor layer(s) but can also be printed or deposited prior to final sintering of the sintered article. In some sintering processes that sinter only discrete pieces (and not continuous ribbons) small sheets (e.g., having length and width dimensions of about 20 cm by 20 cm), the conductor layer(s) are printed after via formation, and/or but on green tape material only. For multi-layer substrates, individual green tape layers are or may be aligned and laminated, with some multi-layer substrates using as many as 30-40 green tape layers. Alumina with tungsten, molybdenum or platinum conductors may be co-sintered and form low firing ceramic packages based on cordierite (glass ceramics) using conductors based on copper. In some embodiments described herein, conductive layer(s) may be formed (i.e., by printing or deposition) prior to the final sintering step, and the technology disclosed herein may help control the dimensions of the vias and conductor patterns during the sintering steps.
Moreover, the continuous sintering processes and system 10 offers means to control the vias spacing and patterns and conductive layer(s) patterns in terms of spacing during the sintering process. Tension in the processing direction during the sintering can stretch the green tape material, partially sintered article, or sintered article and/or bias the sintering shrinkage as disclosed above. This tension can increase the vias spacing and patterns and conductive layer(s) patterns in the processing direction, effectively reducing the sintering shrinkage in the process direction. Differential sintering in the processing direction versus the direction perpendicular to the processing direction may range from about 2% to about 3%, such as where tape is stretched in the processing or lengthwise direction.
Controlled curvature sintering station 38 or curved air bearings can be used to transport the green tape material, partially sintered article, or sintered article in the processing direction 14 and may prevent the green tape material, partially sintered article, or sintered article from having excessive curvature across the width of the green tape material, partially sintered article, or sintered article. If there is a mild cross-ribbon- or sheet-curvature, the tension in the direction parallel to the processing direction may provide some tension perpendicular to the processing direction, controlling or limiting distortion.
Providing tension to the direction perpendicular to the processing direction 14 can be difficult, particularly at the temperatures where the sintered article is plastically deformable and/or is sintering and plastically deformable. Rollers (see, e.g.,
Fiducial marks for alignment can be made by lasers, mechanical means, chemical means such as slight composition changes with visible results. These marks help align further processing steps such as conductor printing, patterning, and/or laminating.
Another aspect of this disclosure pertains to a multi-layer sintered article having a width of about 1 mm or greater, 1 cm or greater, 5 cm or greater, 10 cm or greater, or 20 cm or greater, with a length of 1 m or greater, 3 m or greater, 5 m or greater, 10 m or greater, or 30 m or greater, where the sintered article has a thickness of less than 1 mm, less than about 0.5 mm, less than about 300 microns, less than about 150 microns, less than about 100 microns. In one or more embodiments, the sintered article has a crystalline ceramic content of more than 10% by volume, more than 25% by volume, more than 50% by volume, more than 75% by volume, or more than 90% by volume. The article has at least two layers of sintered articles and may have more than 40 such layers. The sintered article layers have at thickness of 150 microns or less, 100 microns or less, 75 microns or less, 50 microns or less, 25 microns or less, 20 microns or less, 15 microns or less, 10 microns or less, 5 microns or less, and/or such as at least 3 microns (i.e. at least 3 micrometers). In one or more embodiments, the sintered article layers need not be the same composition and some such layers include glass. In some embodiments, such glass layers may include 100% glass, such as at least 100% amorphous silicate glass.
In one or embodiments, the multi-layer sintered article includes a plurality of vias, conductive layer(s) and/or optional additional layers, as described herein with respect to microelectronics articles.
In one or more embodiments, the system 10 may include a process and an apparatus to make such multi-layer sintered articles. The multi-layer can be made by casting or web coating multiple layers of green tape material (i.e., with ceramic particles with polymer binder) over one another. The multi-layer green tape material structure may then be processed through the system 10 as described herein. In one or more embodiments, the multi-layer green tape material structure can also be formed by laminating multiple green tapes with ceramic particles at near room temperature in a continuous fashion and then by feeding the laminated tapes into the system 10. Partially sintered articles can also be laminated together with minor pressure in the sintering station 38. The pressure can be caused by having a mild curvature in the sintering station 38 that the partially sintered articles are drawn across. Each partially sintered article can have its own tensioning and payout speed control means. Each partially sintered article can have fiducial marks to assist alignment of the articles. Tension and payout speed can be used to match sintering shrinkage from article to article to align vias and conductors from article to article. If the fiducial marks are not aligned as the multi-layer article exits the furnace, the layer payout speeds and/or tensions can be adjusted to bring the layers back into alignment. Additional pressure normal to the length and width of multi-layer articles can be provided by rollers at high temperature as described above.
As electrical conductors and ceramic materials in multi-layer electronic substrates may not have the same thermal expansion coefficient, some designs may provide for an overall stress reduction (balance) for “top” side to “bottom” side of the multi-layer sintered articles. In essence such designs have a similar amount of metal or ceramic on the top and bottom of the multi-layer, such as by mirroring the layers about a central plane in the respective stack. With thin ceramic layers, a structure that is not stress/CTE balanced may experience deformation of the ceramic and/or curling of the overall stacked structure.
In one or more embodiments, a circuit board for electronics comprises a sintered article, as described herein, having electronic conductors patterned on it. The conductors for the circuit board may be directly printed onto the green tape material, the partially sintered article, or the sintered article and/or may be printed onto a coating(s) or layer(s) bonded to the green tape material, the partially sintered article, or the sintered article, such as an adhesion promoting layer, a surface smoothing layer, and/or other functional layers. The printing can be from a direct screen printing, electroless deposition and pattering, lithography, using a silicone carrier intermediate between the pattern formation and the application of the pattern on the sintered article by gravure patterning rollers, and/or by other processes.
The conductors for the circuit board can be directly printed on the partially sintered article, after an intermediate firing step but before the final sintering, and/or printed onto coatings thereon. Porosity in the partially sintered article or sintered article can improve adhesion of the conductor print or pattern. The printing can be from a direct screen printing, lithography, using a silicone carrier intermediate between the pattern formation and the application of the pattern on the ceramic by gravure patterning rollers, or other processes.
One aspect of the process and apparatus may be to use a hug drum while simultaneously patterning the long continuous porous ceramic ribbon or sheet. The hug drum pulls the ceramic ribbon or sheet to match the curvature on the surface of the drum, making printing of the conductor pattern less difficult. Photolithography can also be used with solvents or acids to etch or wash away some of the conductor pattern on the green ribbon or sheet prior to final sintering, photolithography can be accomplished on a hug drum. When the conductor is patterned prior to final sintering, a means to control the pattern, size, scale, or pitch with the sintering shrinkage is advisable. Unfortunately, sintering shrinkage of a ceramic ribbon or sheet can vary by a percent or more from one continuous green ribbon (or sheet) to another continuous green ribbon (or sheet), sometimes even within a single green ribbon or sheet. One method to insure an accurate spacing of the conductor pattern is to have a sensor at the outlet of the final sintering step and measure the distance of the conductor pattern spacing. This information can be feed to the printing pattern means (e.g., laser, drill, punch, etch system), photolithography exposure means (e.g., radiation or light source, mask), to adjust the conductor pattern in the pre-final sintered ribbon or sheet to match the current sintering shrinkage. (The length of the ribbon or sheet between the measuring means and the “patterning” means may not be perfectly precise, however may be more accurate than either batch sintering with a periodic kiln or use of a tunnel kiln, such as where a great deal of final product may be lost due to inaccuracy.)
Continuous sintering (e.g., roll to roll sintering, continuous fired ceramic) offers another means to control the via spacing during the sintering process. Tension in the web transport direction (i.e. lengthwise direction for a tape) provided during the sintering can stretch the sintering article (e.g., ribbon or sheet) and/or bias the sintering shrinkage. This tension can increase spacing of the conductor pattern in the ribbon or sheet transport direction, effectively reducing the sintering shrinkage in the ribbon transport direction. Differential sintering in the ribbon transport direction versus the direction perpendicular to the ribbon transport direction has been observed, up to 2 to 3% when tension is applied.
Photolithography, ink jets, atomic layer deposition, some printing and other processing means can be accomplished from the inner radius of a curved air bearing or with a sectioned hug drum with open areas for the exposure of the ceramic ribbon or tape to the conductor pattering processing equipment.
Alumina with tungsten, molybdenum or platinum conductors may be co-sintered with other inorganic materials disclosed herein and form low firing ceramic packages based on cordierite (glass ceramics) using conductors based on copper.
Controlled curvature kiln furniture or curved air bearings, that the ceramic ribbon or web with a conductor pattern is pulled through or over, can keep the ceramic ribbon or sheet with a conductor pattern from having excessive curvature across the short length of the ribbon perpendicular to the ribbon transport direction in some such embodiments.
Providing tension to the direction perpendicular to the ribbon transport direction, (cross web direction), can be difficult, particularly at the temperatures where the ceramic ribbon with conductor pattern is plastically deformable or is sintering and plastically deformable. Rollers angled away from parallel to the ribbon transport direction in the hot zones of the furnace can apply some tension perpendicular to the ribbon transport direction. This tension can increase the spacing of the vias perpendicular to the ribbon transport direction, effectively reducing the sintering shrinkage perpendicular to the ribbon transport direction. The size and pitch of the conductor patterns can be controlled and adjusted with a combination of the sintering shrinkage along the direction parallel to the ribbon transport direction (long length of the ceramic ribbon), sintering shrinkage across the direction perpendicular to the ribbon transport direction, tension in the two directions and the shape of the kiln furnace and/or air bearing that the ceramic ribbon or sheet is on while sintering or hot.
Fiducial marks for alignment can be made by lasers, mechanical means, chemical means such as slight composition changes with visible results. These marks help align further processing steps such as conductor printing/patterning and laminating.
Multi-layer structures with ceramic and conductor may be bonded at high temperature from final sintered conductor plus ceramic sheets or ribbons with fewer layers, even from sheets with only a single ceramic plus conductor layer.
Thin circuit boards with ceramic insulator layers benefit from having a stress balance from top to bottom. This may be accomplished by having a patch or pattern of material printed on the side opposite to the desired conductor pattern that can alleviate the coefficient of thermal expansion CTE or thermal expansion related stress between the conductor and ceramic (and sometimes a sintering differential stress between the conductor and the ceramic). This may take the form of a second conductor layer with a similar thickness and mass of material on the bottom of the board, which balances the CTE stress (and sintering differential stress) from top to bottom leaving the circuit board almost flat, rather than curled.
As the multi-layer structure and/or the circuit board becomes thicker, it becomes stiffer after full sintering. Particularly with 1 mm, 0.5 mm, and 250 micron thickness ceramic and conductor structures, rolling the article on small rolls of 30 to 7.5 cm in diameter can be problematic. Means for cutting the continuously sintered articles by laser, diamond saw, abrasive jet, water jet and other techniques can be adapted to the continuous sintering apparatus, such as where individual or groups of structures may be cut into sheets. The cutting apparatus may be added to the exit of the final sintering furnace, and the cutting means would travel or interface with the long article, such as while it is exiting the furnace.
Referring to
To initiate the reel to reel transfer of tape material from source reel 16A to uptake reel 44A, green tape 20A needs to be threaded through the channels of binder removal station 34A and through sintering station 38A in order for the green tape 20A to be connected to uptake reel 44A which applies the tension to pull green tape through binder removal station 34A and through sintering station 38A. Similarly, if during operation of binder removal station 34A and sintering station 38A the tape material breaks (which may occur following binder removal), the tape material needs to be threaded through binder removal station 34A and then through sintering station 38A while these stations are at full operating temperature. Applicant has determined that threading, particularly when binder removal station 34A and sintering station 38A are at temperature, can be particularly challenging due to the difficulty in threading unbound tape 36 (shown in
As will be discussed in more detail below, Applicant has developed a process utilizing a threading material or leader to pull green tape 20A through binder removal station 34A and sintering station 38A in order to initiate the reel to reel processing discussed above. In such embodiments, the threading material is passed through sintering station 38A and binder removal station 34A, and the leader is coupled to the green tape 20A on the upstream or entrance side of binder removal station 34A.
Tension is then applied from the uptake reel 44A through the leader to green tape 20A to begin the process of moving green tape 20A through binder removal station 34A and through sintering station 38A. While a variety of approaches to threading green tape through binder removal station 34A and through sintering station 38A may allow for sintering of green tape to be achieved (e.g., manual threading), Applicant has determined that the leader based threading process discussed herein provides high quality/low warp in the sintered tape material even at the leading edge of the sintered material. This improved product quality decreases product waste, improves process efficiency by eliminating the need for handling/removal of warped sections on the green tape and improves integrity of the wind of sintered material on uptake reel 44A due to the shape consistency along the length of the sintered tape material. In addition, in the context of hot threading (e.g., threading when binder removal station 34A and sintering station 38A are at temperature), Applicant has found that use of the leader based process discussed herein provides an efficient way to support and pull the leading edge of the delicate, unbound portion of tape material (e.g., unbound tape 36 shown in
In the embodiment shown in
Green tape 20A is moved from source reel 16A (e.g., via unwinding of green tape 20A from the reel as discussed above) toward entrance opening 116A of binder removal station 34A such that a leading section 1506A of green tape 20A is located adjacent to and overlapping end section 1504A of leader 1502A. As shown in
Once leader 1502A is coupled to green tape 20A, a force is applied to a portion of leader 1502A located outside of (e.g., downstream from) binder removal station 34A and sintering station 38A such that leader 1502A and green tape 20A are pulled in the processing direction 14A through binder removal station 34A and sintering furnace 38A. In the specific embodiment shown in
Thus, through the use of leader 1502A, the downstream or rewind side of system 1500A is initially coupled to the upstream or unwind side of system 1500A, allowing for the initiation of reel to reel sintering of the material of green tape 20A. In addition, by providing this initial threading of binder removal station 34A and sintering station 38A via connection between the same unwind and uptake systems that advance green tape 20A during sintering processing, the leader-based threading process discussed herein is able to establish the proper tension and velocity for the entire length of green tape 20A that traverses binder removal station 34A and sintering station 38A, including the leading section 1506A of green tape 20A at the overlapped location. Further, by providing a horizontal pulling force through leader 1502A, the leader based process discussed herein allows for threading through the horizontally orientated channels of binder removal station 34A and sintering station 38A, which can otherwise be difficult (particularly given the delicate nature of the tape material following binder removal).
As discussed above in detail regarding system 10, binder removal station 34A is heated to remove or burn off binder from green tape 20A, and sintering station 38A is heated to cause sintering of the inorganic material of green tape 20A. In one potential use of the threading process discussed herein, binder removal station 34A and/or sintering station 38A are already at their respective operating temperatures when leader 1502A is threaded. This is the case when leader 1502A is used to thread green tape 20A following a break in the material during reel to reel sintering. In another potential use of the threading process discussed herein, binder removal station 34A and/or sintering station 38A are at a low temperature (e.g., below their respective operating temperatures, off at room temperature, etc.) when leader 1502A is threaded through. This is the case when leader 1502A is used to thread green tape 20A during initial start-up of system 1500A.
As discussed in more detail above, following the initial movement of the join or overlap between leader 1502A and the leading section 1506A of green tape 20A through binder removal station 34A and sintering furnace 38A, green tape 20A is continuously unwound from source 16A and moved through stations 34A and 38A, forming the length of sintered material as discussed above. Following sintering the sintered material is wound onto uptake reel 44A. In one embodiment, leader 1502A is decoupled from the sintered tape material once leading section 1506A of green tape 20A exits from sintering station 38A, and prior to winding of the sintered tape material onto uptake reel 44A. In another embodiment, leader 1502A is wound onto uptake reel 44A along with the sintered tape material forming the innermost layers of the reel including the sintered material.
In various embodiments, leader 1502A is an elongate and flexible piece of material that is able to resist the high temperatures of binder removal station 34A and sintering station 38A. In the coupling process shown in
In some embodiments, an adhesive material 1510A is used to form a bond joining leader 1502A to green tape 20A. As shown in
In various embodiments, Applicant has determined that the volume of adhesive material 1510A used as well as the shape of the applied adhesive material 1510A on leader 1502A influences the properties of the bond formed between leader 1502A and green tape 20A. In specific embodiments, adhesive material 1510A is a small volume (e.g., about 0.1 mL of an alumina-based adhesive material). In one embodiment, adhesive 1510A is used to bond a leader 1502A to an unsintered green tape material 20A, and in such embodiments, Applicant has found that a round dot of adhesive 1510A works well. Applicant hypothesizes that the round geometry helps to distribute the thermal and mechanical stresses induced by cement and tape shrinkage and CTE mismatch (if any) between the materials of leader 1502A, adhesive 1510A and green tape 20A. In another embodiment, adhesive 1510A is being used to bond a leader 1502A to a tape of partially sintered material, and in such embodiments, Applicant believes that a line of adhesive 1510A extending across the width of leader 1502A works well. Applicant hypothesizes that the line geometry acts to apply an even constraint across the web as it moves through the sintering station.
In specific embodiments, binder removal station 34A is operated to remove liquid and/or organic components from adhesive 1510A (as well as from green tape 20A) as the overlapped section 1512A between leader 1502A and green tape 20A traverses binder removal station 34A. Applicant believes that various properties of the adhesive material 1510A and of green tape 20A relate to the likelihood that the bond formed by adhesive material 1510A will break during traversal of binder removal station 34A and sintering station 38A. Applicant hypothesizes that the temperature profile through binder removal station 34A can cause the organic material in green tape 20A to soften and even melt prior to evolving from the tape, which can help to limit the stress intensity around the cement join as the individual components begin to change shape/size due to shrinkage and thermal expansion. Applicant hypothesizes that allowing green tape to ‘deform’ or re-form around the location of adhesive 1510A, prior to losing its elastic/plastic properties helps to decrease defects and improves the quality of the bond formed by adhesive 1510A. Similarly this elastic/plastic property may also allow for venting of liquids and organic materials from adhesive 1510A, which may otherwise cause an increase in pressure between leader 1502A and green tape 20A. This increase in pressure may cause the bond to fail or the gas build up may rupture through green tape 20A.
In specific embodiments, the tension applied during the process of pulling the overlapped section or join between leader 1502A and green tape 20A may be changed or increased as overlap section 1512A traverses binder removal station 34A and/or sintering station 38A. In a specific embodiment, a low level of tension, e.g., of below 25 grams, is provided initially, during traversal of overlap section 1512A across binder removal station 34A, and then tension is increased as the overlap section 1512A traverses sintering station 38A. In a specific embodiment, tension on the order of 25 grams or more is applied once overlap section 1512A and adhesive material 1510A reaches the center of sintering station 38A. Applicant believes that tension at this point can be increased without separation of the bond between leader 1502A and green tape 20A because of the sintering of material of green tape 20A that has occurred at this point. Applicant believes that applying a high level of tension too early, before the strength has had a chance to develop will generally lead to failure of the bond formed by adhesive 1510A.
In various embodiments, coupling and/or support between leader 1502A and green tape 20A is enhanced by various levels of overlap between leader 1502A and green tape 20A. As can be seen in
In various embodiments, Applicant has identified a number of material combinations for leader 1502A, green tape 20A, and adhesive 1510A that provide the threading properties/functionality discussed herein. In general, leader 1502A is formed from a material that is different in at least one aspect from green tape 20A. In some such embodiments, leader 1502A is formed from the same material type as the inorganic grains of green tape 20A but has a different (e.g., higher) degree of sintering than the inorganic material of green tape 20A. In some such embodiments, leader 1502A is an elongate tape of sintered ceramic material, and green tape 20A supports unsintered or less sintered grains of the same type of ceramic material.
In some other embodiments, leader 1502A is formed from an inorganic material that is different from the material type of the inorganic grains of green tape 20A. In a specific embodiment, leader 1502A is formed from a ceramic material type that is different than the ceramic material type of the inorganic grains of green tape 20A. In some other embodiments, leader 1502A is formed a metal material, while the inorganic grains of green tape 20A are a ceramic inorganic material.
Applicant has found that the coupling arrangements shown in
Leader 1502A can be formed from a variety of suitable materials. In some embodiments, leader 1502A is formed from a sintered ceramic material, and in other embodiments, leader 1502A is formed from a metal material. In some embodiments, Applicant has found that using a porous ceramic material for leader 1502A increases the ability of adhesive material 1510A to bond to leader 1502A. Applicant believes that the porosity of leader 1502A allows adhesive material 1510A to bond more easily than if the leader had a less porous or polished surface. In specific embodiments, leader 1502A may be a platinum ribbon or a fully sintered ceramic material, such as alumina or yttria stabilized zirconia (YSZ)
In specific embodiments, leader 1502A is sized to allow handling and coupling to green tape 20A. In specific embodiments, leader 1502A has a width that substantially matches (e.g., within plus or minus 10%) of the width of green tape 20A. In specific embodiments, leader 1502A has a thickness of between 5 μm and 500 μm and more specifically a thickness within the range of 20 to 40 μm. Further, leader 1502A has a length sufficient to extend from uptake reel 44A through both sintering station 38A and binder removal station 34A and thus the length of leader 1502A varies with the size of system 1500A.
While
Adhesive material 1510A can be formed from a variety of suitable materials. In some embodiments, adhesive material 1510A is a ceramic adhesive material. In specific embodiments, adhesive material 1510A is an alumina-based adhesive material, such as alumina-based adhesive #C4002 available from Zircar Ceramics.
Referring to
Some continuous tape sintering processes may be susceptible to certain flatness distortions (e.g., cross-width bowing, edge wrinkle, bubble formation, etc.) believed to be formed due to creation in-plane stresses within the tape material during sintering. For example, Applicant has found that due to a variety of factors, such as variations in ceramic particle density in unbound tape 36B, large temperature differentials within the tape material along the length of the systems (e.g., which may be in excess of 1000 degrees C. due to the continuous nature of the systems and processes discussed herein), processing speeds, etc., contribute to the generation of the in-plane stresses during sintering, which in turn may induce buckling in the absence of a countervailing application of force in a manner that allows for release of these in-plane stresses.
For example, an alumina tape undergoing continuous sintering via the systems discussed herein may have regions simultaneously at room temperature and at the maximum sintering temperature. There may also be regions of the tape beginning the sintering process where shrinkage is minimal and areas of the tape where sintering is nearly complete, where the shrinkage exceeds 8% or even 10% on a linear basis. The gradient in shrinkage and temperature may be sources of complex, biaxial stresses that may induce distortions, such as by curling and wrinkling, even in a tape that enters the sintering station having a level of flatness. Such distortions may then become frozen into the sintered tape following cooling, thereby degrading its potential uses.
As will be discussed in detail below, Applicant has determined that stresses that may cause flatness distortions can beat least in part counteracted by inducing a lengthwise or longitudinal curve in the tape during sintering. During sintering, the tape material plastically relaxes and deforms to the shape of the induced lengthwise bend, which generates forces within the tape material that tends to reduce in-plane stresses that may otherwise occur, and a result may be to produce a sintered tape with a high level of cross-width flatness. Applicant believes that by utilizing lengthwise bending during sintering, a flatter sintered tape can be produced despite variations in green tape particle density and high production speed.
Further, in at least some embodiments, the flattening process discussed herein produces flat, thin sintered articles while avoiding/limiting surface contact and the resulting surface defects and scratches common with contact/pressure-based flattening devices, such as may be experienced when pressing a material between cover plates during sintering. As will be shown below, Applicant has developed a number of systems and processes for inducing the longitudinal bend that leave at least one major surface of the tape untouched during sintering, and some processes that leave both upper and lower (major) surfaces of the tape untouched during sintering. Applicant believes that other ceramic sintering processes may not achieve the high levels of cross-width flatness, in a continuous sintering process or with the limited degree of surface contact provided by the system and processes discussed herein.
Referring to
In the specific embodiment shown in
As shown in
In the specific embodiment shown in
As discussed above regarding system 10, sintering station 38B is arranged such that a plane intersecting the entrance and the exit of the sintering station forms an angle relative to a horizontal plane that is less than 10 degrees. As discussed above, this generally horizontal sintering arrangement allows unbound tape 36B to move through sintering station 38B in a generally horizontal position. In such embodiments, curved surface 1604B defines the lower surface of the path that tape 36B traverses between the entrance and exit of sintering station 38B. Applicant believes that by combining the horizontal sintering arrangement (discussed as reducing air flow-based thermal gradients above) with the formation of the longitudinal curved shape in the tape during sintering, sintered tape with the high levels of flatness discussed herein can be produced and/or may be produced at rapid speeds, far faster than other sintering systems. It should be understood that while Applicant believes that the bending during sintering in combination with the horizontal sintering station 38B provides high levels of flatness, in other embodiments, sintering station 38B may be arranged at any angle from horizontal to vertical. In such non-horizontal embodiments, the dimensions and positioning of curved surface 1604B may be sufficient to achieve the desired level of flatness.
As shown in
In general, tape portion 1606B has a porosity that decreases or degree of sintering that increases in the processing direction (e.g., from right to left in the orientation of
As will generally be understood from the description of the unwind and take-up portions of system 10 discussed above, system 1600B provides for continuous, reel-to-reel processing of a long contiguous length of tape. In this manner, the entire contiguous length of tape being processed may be moved continuously and sequentially through sintering station 38B such that the entire contiguous length of the tape being processed experiences bending to the radius of curvature, R1B, of upward facing, convex curved surface 1604B during traversal of sintering station 38B.
Referring to
As will generally be understood, in various embodiments, the radius of curvature that defines continuous convex curved surface 1604B is a function of maximum rise, H1B, and the longitudinal length, L2B, of surface 1604 (e.g., the distance in the horizontal orientation of
In specific embodiments, insert 1610B is removable from channel 104B and is removably coupled to or supported by tube 1608B. In such embodiments, this allows the different inserts 1610B having differently curved surfaces 1604B to be placed into sintering station 38B to provide a specific bend radius needed to provide a desired level flattening for a particular process or tape material type, thickness, rate of sintering, etc.
Referring to
In some embodiments, downward facing, concave curved surface 1612B is a surface of an insert 1614B. In such embodiments, insert 1614B is removably coupled to or supported by tube 1608B which allows insert 1614B to be selected to match the curvature of the lower furniture 1610B as may be used for a particular process or material type.
Referring to
Further, as shown in
Referring to
Referring to
The flattening provided by bending tape 36B around a curved structure, such as roller 1642B, is explained in more detail in relation to
σd=Eκdt
where t is the thickness of the tape and E is its elastic modulus. This technique helps reduce other flatness distortions such as edge curl or bubble formation, with the result that local stress may be proportionate to the local curvature. Thus, bending, such as around roller 1642B or along surface 1604B discussed above, aids in flattening across many defect types. As will be explained in more detail below regarding
However, utilizing a curved surface such as the outer surface of roller 1642B or surface 1604B, discussed above, is advantageous in that it allows a tensile force to be applied externally to the tape, by devices such as a weighted dancer 1680B (
where w is the width of the tape and θw is the angle of contact between as the curved surface (whether the outer surface of roller 1642B or surface 1604B) and tape 36B, often referred to as the wrap angle.
In various embodiments, roller 1642B can be fixed and unable to rotate. In other embodiments, roller 1642B may rotate freely. In yet other embodiments, the rate of rotation of roller 1642B may be controlled to match the speed of conveyance of the tape or even to drive or retard conveyance. In various embodiments, roller 1642B may also be configured to move up or down normal to the tape to change the wrap angle.
As shown in
Referring to
Applicant has performed tests that demonstrate that longitudinal bending while sintering of various contiguous tape materials decreases flatness distortions. Some results from these tests are illustrated in
Referring now to
Accordingly, aspects of the present disclosure, as discussed above, relate to a roll of flat or flattenable polycrystalline ceramic or synthetic mineral tape of materials disclosed or described herein, such as alumina tape as in
According to an exemplary embodiment, an article (e.g., tape of sintered ceramic, as disclosed herein), has a thickness of less than 50 micrometer or other thicknesses as disclosed herein, and fewer than 10 pin holes (i.e., passage or opening through body from first to second major surface having a cross-sectional area of at least a square micrometer and/or no larger than a square millimeter), per square millimeter of surface on average over the full surface (or fewer than 10 pin holes over the full surface, if the surface area is less than a square millimeter; or alternatively on average over a long length of the article, such as over 1 meter, over 5 meters), such as fewer than 5 pin holes, fewer than 2 pin holes, and even fewer than fewer than 1 pin hole per square millimeter of surface on average over the full surface or long length. Pin holes are distinguished from vias, which are purposely cut, typically in pattern of a repeating geometry (e.g., circular, rectilinear) to be filled with conductive material for example, or perforations formed in a pattern of a repeating geometry, which may help as fiducial marks with alignment in roll-to-roll processing for example.
Some embodiments may use multiple passes through a furnace for sintering the same article (e.g., tape), such as a first pass (“bisque pass”) to increase strength of the tape after organic binder is removed, as second pass to partially sinter the tape, a third pass to further sinter the tape, and a forth pass to sinter to final density. Use of multiple passes or a series of furnaces or hot zones may help to control stresses in the tape due to shrinkage of the tape material during sintering. For example, some furnaces for sintering may be 12 to 14 inches long, while others may be 40 to 45 inches long, others over 60 inches, and still others of other lengths. For shorter furnaces, multiple passes or arrangements of multiple furnaces in series may be particularly helpful for sintering inorganic materials with greater degrees of shrinkage. Also, longer furnaces or arrangements of furnaces in series may also allow for faster rates of green tape movement, by increasing soak times (i.e. exposure to sintering conditions) at such faster rates.
After analyzing samples sintered at a high speed (e.g., rate of 4 inches per minute) with a sintering temperature (e.g., 1650° C.), that are particularly thin, as described herein (e.g., a thickness of 20 to 77 micrometers), alumina or other materials disclosed herein made with the presently disclosed technology may have the following attributes: material purity of at least 90% by volume, such as at least 95%, such as at least 99%, where high purity may result from the narrow passage and control of air flow as well as the time of sintering, efficiency of the binder removal, and starting constituents, among other factors described herein; surface roughness measured by AFM in units of nanometers of less than 100, such as less than 60, such as about 40 for shiny face and/or less than 150, such as less than 100, such as about 60 for mat face, when measured at a 30 mm scan, where the mat face is rougher than the shiny face due to interface with a floor of the sintering furnace; grain size of about 1 mm in cross-section, or other grain sizes as disclosed herein; porosity of less than 10% by volume for a sintered article, such as less than 5%, such as less than 3%, such as less than 1%, such as less than even 0.5%, which may in part be due to the fast firing process, which maintains small grain/particles sizes as disclosed above, whereby gas may be less likely to be trapped within grains, as may be a characteristic limitation for traditional batch sintering and longer firing processes (limiting phenomenon known as ‘pore/boundary separation’ which may be overcome by sintering processes as disclosed herein). Alumina tape manufactured according to technology disclosed herein has a specific heat capacity of at least and/or no more than about 0.8 J/gK at 20° C. and 1.0 J/gK at 100° C. as measured via ASTM E1269 standard test protocol/method; hardness at room temperature (23° C.) measured via nano-indentation of at least and/or no more than about 23.5 GPa, such as on at least and/or no more than about a 40 μm thick alumina tape, and/or other tape or sheet sizes disclosed herein; two-point bending strength of at least and/or no more than about 630 MPa, such as at least in part due to control of voids and smaller grain size; elastic modulus of at least and/or no more than about 394 GPa as measured via dynamic mechanical analysis (DMA) for 3 point bend; coefficient of thermal expansion of at least and/or no more than about 6.7 ppm/° C. average over the range of 25-300° C., at least and/or no more than about 7.6 ppm/° C. average over the range of 25-600° C., at least and/or no more than about 8.0 ppm/° C. average over the range of 25-300° C.; dielectric strength of at least about 124.4 kV/mm at 250° C. as per ASTM D149 standard test protocol/method, such as on at least and/or no more than about a 40 μm thick alumina tape; dielectric constant (Dk) of at least and/or no more than about 9.4 at 5 GHz and of at least and/or no more than about 9.3 at 10 GHz as per ASTM D2520 standard test protocol/method; dielectric loss/loss tangent of at least and/or no more than about 8×10−5 at 5 GHz and of at least and/or no more than about 1×10−4 at 10 GHz as per ASTM standard test protocol/method (D2520); volume resistivity of at least and/or no more than about 3×1015 ohm-centimeter at 25 as per D257, at least and/or no more than about 4×1014 ohm-centimeter at 300 as per D1829, and/or at least and/or no more than about 1×1013 ohm-centimeter at 500 as per D1829; transmittance of at least about 50%, such as at least about 60%, such as at least about 70% for one, most, and/or all wavelengths between about 400-700 nanometers, such as on at least and/or no more than about a 40 μm thick alumina tape, and/or other tape or sheet sizes disclosed herein; transmittance of at least about 50%, such as at least about 65%, such as at least about 80% for one, most, and/or all wavelengths between about 2-7 micrometers and/or between about 2-7 millimeters, such as on at least and/or no more than about a 40 μm thick alumina tape, and/or other tape or sheet sizes disclosed herein; and less than 100 ppm outgassing as measured via GC-MS at 200° C., such as less than 50 ppm, such as less than 10 ppm.
Referring now to
Referring now to
Applicants have also found that the presently disclosed sintering system may be advantageous for pore removal during sintering, such as when rapidly sintering lithium-containing inorganic materials, such as LiMn2O4, and/or other materials susceptible to vaporization of volatile constituents. With conventional sintering techniques, grain growth may limit pore removal, such as by trapping pores within larger grains.
For comparison purposes, Applicants manufactured a pill of die-formed LiMn2O4 sintered at 1300° C. The mean particle diameter of the powder used to make the pill was 0.5 μm; to enhance surface tension and favor pore removal. Loss of lithium and change of Mn-valence were controlled or slowed in three ways. First, the size of the pill was large, greater than 25 mm in diameter and 5 mm in thickness to provide surplus material. Second, the sintering was performed under a cover. Third, the pill was supported on platinum. Powder x-ray diffraction confirmed the resulting pill is single phase lithium manganite spinel and chemical analysis shows negligible lithium loss relative to the as-received material and that the average valence of Mn is 3.5. The average grain size of the sintered pill is about 40 μm and there is more than 15% of porosity.
Returning to the presently disclosed technology, porosity in sintered materials may be limited or particularly low, and grains may be particularly small, which may be beneficial in applications, such as cathode support. By contrast, excess porosity and large grains may be detrimental to strength of most ceramics. Further, Applicants have found that rapid thermal sintering, using techniques and equipment disclosed herein, favors pore removal over grain growth. Referring to
LiCO2 and LiFePO4 are other examples of lithium-containing inorganic materials that may be sintered using the presently disclosed technology, and may be useful as cathode material or for other applications. More generally, sintering of other transition metal oxides with minimal loss of oxygen is possible is possible using the presently disclosed technology.
Referring now to
In this example, the binder was subsequently burned off of the green tape of
Using the presently disclosed technology, some embodiments include use of high-lithium content for forming particularly dense garnet tape or other articles. Applicants have found that excess lithium (excess in terms of more than the lithium according to stoichiometry of the sintered article, such as at least 1 vol % excess, at least 10 vol % excess, at least 20 vol % excess, at least 50% vol %, and/or no more than 100 vol % more than the stoichiometric amount in the sintered article) in the green tape may promote dense garnet tape sintering and/or compensate for loss of lithium during the sintering. Such high-lithium content powder for use in the green tape may be made by batching with excess amounts of lithium precursor in the raw material in garnet powder preparation and/or by making stoichiometric or slightly excess (no more than 50 vol % excess relative to final article stoichiometry) lithium garnet powder and then adding in more lithium precursor during slip preparation for tape casting. Some advantages of the latter approach include that the lower lithium-containing batch may be easier to prepare because high lithium content may be hygroscopic and difficult to mill and/or the amount of excess lithium may be easily adjusted to compensate for different processing conditions. Examples of lithium precursors for adding such excess lithium during the slip preparation include Li2CO3, LiOH, LiNO3, LiCl, etc. Methods of adding excess lithium as just described include having lithium precursor pre-react with the garnet powder, such as by heating the lithium precursor and garnet powder mixture to about 900 to 950° C. for about 1 to 5 hours. Alternatively, without pre-reaction, the excess lithium may be added as a fine precursor powder and/or by providing enough milling to decrease the particle size to prevent leaving pores in the ceramic, such as precursor powder particle size of less than 3 micrometers, such as less than 1 micrometer. Applicants have found that the amount of excess lithium is enough for sintering via the above-described technology, but not too much so as to leave excess lithium in the sintered article or to cause tetragonal phase formation. Accordingly, at least and/or no more than about 5.8 to 9 mol total lithium per mol of garnet, for garnet that sinters at at least and/or no more than about 1000° C. in at least and/or no more than about 3 minutes (e.g., low lithium-content garnet); at least and/or no more than about 7 to 9 mol total lithium per mol of garnet, for garnet that sinters at at least and/or no more than about 1150° C. in at least and/or no more than about 3 minutes. With that said, for garnet, especially high lithium-content garnet, that may be highly reactive to organics used in tape casting slip, to stabilize the garnet, the powder may be treated beforehand using an acid treatment, such as peracetic acid (peroxyacetic acid, PAA), citric acid, stearic acid, hydrochloric acid, acetic acid; a solvent, such as a non-water containing solvent, such as isopropyl alcohol, PA, PP, etc.; with a treatment of soaking the garnet powder, which may be excess lithium precursor pre-reacted garnet powder as disclosed above, in 1 to 5 wt % acid/solvent solution for 2 hours, with solid loading of about 50%, then drying the solvent, where the obtained/treated powder may be used for making tape casting slip. Alternatively, low lithium-content garnet powder plus inert lithium precursor, such as Li2CO3, may be used in making a casting slip directly.
At least one embodiment of acid treatment includes ball milling for 3 hours and oven drying at 60° C. 100 grams of MAA (Li5.39La3Zr1.7W0.3Ga0.5Ox, lithium garnet or cubic LLZO (e.g., Li7La3Zr2O12), low lithium-content garnet powder) plus 10.7 grams Li2CO3, 2.2 grams of citric acid, and 100 grams of isopropyl alcohol. At least one embodiment of tape casting slip manufacturing includes attrition milling for 2 hours 100 grams of acid treated MAA plus 10.7 wt % Li2CO3, 84.67 grams methoxy propyl acetate solvent, 12.14 grams PVB Butvar B-79 binder, and 2.4 grams dibutyl phthalate plasticizer. Another embodiment of tape casting slip manufacturing includes attrition milling for 2 hours 100 grams of acid treated MAA plus 8.4 wt % Li2CO3 that has been pre-reacted in turbular mix for 30 minutes and calcine at 900° C. for 1 hour, 66.67 grams ethanol and 33.33 grams butanol solvent, 12 grams PVB Butvar B-79 binder, and 10 grams dibutyl phthalate plasticizer. Another embodiment of tape casting slip manufacturing includes 100 grams of GP (Li6.1La3Zr2Al0.3 O12, lithium garnet or cubic LLZO) plus 8.4 wt % Li2CO3 that has been pre-reacted (e.g., mixed for 30 minutes and heated to 900° C. for 1 hour), 66.67 grams ethanol and 33.33 grams butanol solvent, 12 grams PVB Butvar B-79 binder, and 10 grams dibutyl phthalate plasticizer. Applicants have found that low lithium content garnet with Li2CO3 for excess lithium precursor, as described above, may not require acid treatment; for example, attrition milling for 2 hours 100 grams of MAA with 10.7% Li2CO3, 84.67 grams methoxy propyl acetate solvent, 2.08 grams fish oil (Z1) dispersant, 12.14 grams of PVB Butvar B-79 binder, and 2.4 grams of dibutyl phthalate plasticizer. Alternatively, acid based dispersant may be added into the slip, such as with up-milling for two hours 100 grams MAA with 10.7% Li2CO3, 104 grams EtOH and BuOH in a 2:1 ratio solvent, 1 gram of citric acid as dispersant, 16 grams PVB B-79 as binder, and 14 grams of dibutyl phthalate as plasticizer.
Aspects of the present technology relate to sintering of higher viscosity, higher processing temperature glasses, such as fused silica or ultra-low-expansion (amorphous) glass compositions that may be difficult or impossible to manufacture as rolls of high viscosity glass tape and/or cut into sheets via other methods, such as fusion drawing, float glass, or other ordinary glass tank melters. Accordingly, inorganic material with geometries (e.g., thicknesses, rolled format, lengths, widths) and attributes (e.g., flatness, low warpage) disclosed herein include higher viscosity, higher processing temperature glasses manufactured with the present technology. Additional benefits of the present technology include compositional homogeneity at small (sub-millimeter) length scale and large length scale (millimeter to multi-centimeter variations) via use of controlled air flow during sintering, tension control of the tape, and mixed powders in a slurry as opposed to flame deposition techniques, which may lead to compositional variations at different scales. Additionally, the rolls or sheets of higher viscosity, higher processing temperature glasses may be annealed. Applicants have found that the presently disclosed technology, including furnace with heat zones, not only allows sintering but also an ability to continuously anneal the glass tape as it is being formed and/or via a set of one or more lower temperature furnaces. A corresponding low and uniform stress field in annealed glass facilitates uniform dimensional changes during post-firing leading to less warpage in thin, post-treated annealed sheets compared to unannealed articles. Further, technology disclosed herein, including lower temperature processing (compared to flame deposition with temperatures typically greater than 2100° C.) and rapid sintering (compared to batch sintering), also facilitates incorporation of volatile dopants such as boron and phosphorous at levels greater than 0.5 wt % of such inorganic material (e.g., viscous, high temperature amorphous glasses), which may be difficult or impossible to add via flame deposited materials. With that said, equipment disclosed herein may be used to heat green or partially sintered materials to a higher temperature than would typically be used in a conventional sintering process, where the short time at soak limits grain growth and accelerates pore removal.
Applicants have found a high level of compositional homogeneity with viscous, high temperature amorphous glass articles, when green tape is made with glass powder mixed in slurry form, such as in the solgel, extrusion, or casting processes and sintering is performed as described above. More specifically, Applicants have found hydroxide (OH), deuterium (OD), chlorine (Cl) and fluorine (F) variations less than +/−2.5 ppm at spatial variations of 1 mm and less than +/−5 ppm within distances 3 cm, such as with variations less than +/−1 ppm at frequencies less than 1 mm and less than +/−3 ppm at frequencies less than 3 cm. In some embodiments, compositional homogeneity is with chemical variations of titania of less than +/−0.2 wt %, such as less than +/−0.1 wt % at distances of 1 mm in titania containing glass, and less than 10 wt % at distances of 1 mm variations in Germania levels in Germania containing glass. In some embodiments, index variations less than 10 ppm, such as less than 5 ppm as measured via XRF techniques (wt % metals) when mixed component glasses are used.
Referring now to
Applicants have found that cooling rate differences resulting from air flow differences, turbulence in air flow, as well as radiative cooling or heating differences from surrounding furnace environments or fixturing may produce localized stress differences in the glass as the glass cools to temperatures below the anneal point, which are locked into the glass. Compositional variations may also impact glass viscosity, and these compositional differences may result in different stresses, fictive temperatures, index of refractions, thermal expansions. If the glass is next re-heated to temperatures where the free standing glass could deform, then unconstrained glass warpage may occur. Such reheating may be needed in downstream processing, such as for thin film deposition for example and warping may be undesirable. However, Applicants have found that annealing glasses manufactured via processes disclosed herein, such as by controlled cooling in a multi-zone furnace, or by passage through an annealing furnace subsequent to sintering (opposite the binder burnout system), helps mitigate differences in tension across the article (e.g., sheet) width as the glass is being rolled and/or helps mitigate instances of different stress levels remaining trapped in the glass. Low and uniform stress levels are identified in glass taken from the roll and left free standing. More specifically, absolute stress levels less than 10 MPa with variations across the article (e.g., sheet or tape) less than +/−5 MPa are identified when the tape is freely resting on a flat surface, such as with absolute stress levels less than 5 MPa with variations less than +/−2 MPa, such as with absolute stress fields less than 2 MPa with variations less than +/−1 MPa. Some embodiments of the present disclosure include glass, as described, having a relatively uniform structure in terms of fictive temperature, such as variations less than +/−20° C., such as less than +/−10° C., such as less than +/−5° C. as measured by FTIR across a width of the respective article. Uniform structure in terms of fictive temperature, may influence properties of the glass, such as optical or thermal expansion of the glass, such as where better expansivity may be obtained via uniform lower fictive temperature, for example.
As indicated above, the present technology may be uniquely suited to process thin ribbons or sheets of viscous, high temperature amorphous glasses. Such glasses may have a viscosity of 12.5 poise only at temperatures exceeding 900° C., where at lower temperatures the viscosity is higher than 12.5; such as a viscosity of 13 poise only at temperatures exceeding 900° C., such as only at temperatures exceeding 1000° C., as shown in
Use of slurries for green tape and the sintering system disclosed herein may help make glass with low solid inclusion levels via purification processes and also low seed or low gaseous inclusion levels. For example, liquid filtering of the slurry prior to casting is one such process, such as for example where sub-micron (e.g., 22 m2/g) powder mixed in the solvents may be filtered through different size filters (40 to 200 μm sieves for example) in order to capture larger size solid defects, such as solid oxide debris or organic debris such as hair. Also, debris may be removed via different settling rates in suspensions, such as where higher density agglomerated particles settle faster than dispersed silica and lighter organic impurities rise to the surface. A middle percentage, such as the middle 80%, could then be used to cast. Centrifuges may accelerate the settling or rising process.
Uniform, consistent and filtered slurry that has been thoroughly degassed (or de-aired) prior to casting to create a very uniform and consistent tape may help minimize the seed levels. Index matching tapes may also facilitate detection of both seeds and solid inclusions. The binder burn out step described above, to remove organics, may occurs at temperatures less than 700° C., and oxygen at elevated temperatures may help remove final residues of carbon, which could be trapped or react with silica to create gases such as CO or CO2 and SiO.
The particularly thin forms of at least some articles described herein have short permeation paths for gases, which result in very little trapped gases even when air is used. To further minimize trapping of insoluble gases such as argon, nitrogen, and (to a lesser extent) oxygen, consolidation in an air free atmosphere may be used, such as in vacuum and/or vacuum with helium or hydrogen, or atmospheric helium or hydrogen, or mixtures thereof. If the consolidating glass has trapped these gases (helium or hydrogen), then the gases may permeate out of the structure in minutes or seconds at any reasonable temperature greater than 1000° C. and leave behind a vacuum or seed with no gases present. The seed may then collapse from atmospheric pressure combined with capillary stresses at temperatures where glass deformation occur. In most, seed minimization would take place preferably during the consolidation operation, prior to annealing. However, the glass could be reheated to outgas trapped gas, collapsed the seeds. and then annealed. Accordingly, at least some embodiments include glass articles (e.g., rolls, tapes, sheets) with little to no trapped gas, such as less than 5% by volume, such as less than 3% by volume, such as less than 1% by volume.
Some embodiments of the present invention, as disclosed above, may use rollers within the sintering furnace to control tension, speed, deformation, or other attributes of the article (e.g., tape or ribbon) during sintering. According to some embodiments, the rollers rotate at different speeds from one another, such as a function of shrinkage of the respective article. For example, in at least one embodiment the furnace includes at least two rollers, wherein a first roller interfaces with a less sintered portion of the article, and the second roller interfaces with a more sintered portion of the article. The second roller rotates at a slower speed than the first roller. In some such embodiments, rotation of the roller(s) within the furnace correspond to free body sintering rates of the respective article being sintered, or have a slightly greater speed to impart tension in the article, such as to flatten the article or control warp. The rollers may be made from refractory materials. Stationary supports (e.g., furnace floor) may be located between rollers in the furnace. In contemplated embodiments, multiple rows of rollers at different levels within the furnace may be used, such as to increase output and/or control airflow within the furnace. Such rollers may be used with lengths of rigid materials, such as rods or sheets.
Referring to
Referring to
In some embodiments, a lithium-containing garnet article (e.g., sheet, tape) of the present disclosure may be integrated in electronics, such as a solid state lithium battery as an electrolyte, such as positioned between an anode and cathode, as shown in
Referring to
Applicants have found that use of “excess” volatile constituents (e.g., lithium) in the green material greatly improves resulting ceramic tape. For example, without excess lithium, lithium lost from garnet due to vaporization may result in a second phase material, such as La2Zr2O7“pyrochlore,” which may act as an insulator and inhibit sintering. Accordingly, ceramic with pyrochlore may result the material that is highly porous, mechanically weak, and/or has poor conductivity. Put another way, Applicants believe that cubic phase, sintering extent and density (inverse of porosity), strength, and ionic conductivity all decrease as pyrochlore phase increases, such as from lithium loss.
In other examples, Li6.5La3Zr1.5Ta0.5O12 with 11.98 wt % Li2CO3 added in the slip of the tape cast, cast with 10 mil blade, had binder burned off in an argon atmosphere, and then was sintered using the technology disclosed herein for 15 or 8 minutes in air.
As indicated above, the present technology (e.g., binder burn-off, sintering station with multi-heat zones and air flow control, tension control, etc.) may be used to sinter green material (tape or other articles) to have the structures, geometries, and properties/attributes disclosed herein, such as green material that includes an organic binder (e.g., polyvinyl butyral, dibutyl phthalate, polyalkyl carbonate, acrylic polymers, polyesters, silicones, etc.) supporting particles of inorganic material, such as polycrystalline ceramic, synthetic mineral, viscous glasses that may be hard to otherwise process into a thin tape or ribbon structure for roll-to-roll manufacturing, or other inorganic materials (e.g., metals, less viscous glasses). For example, the inorganic materials include zirconia (e.g., yttria-stabilized zirconia, nickel-yttria stabilized zirconia cermet, NiO/YSZ), alumina, spinel (e.g., MgAl2O4, zinc ferrite, NiZn spinel ferrite, or other minerals that may crystallize as cubic and include the formulation of A2+B23+O42−, where A and B are cations and may be magnesium, zinc, aluminum, chromium, titanium, silicon, and where oxygen is the anion except for chalcogenides, such as thiospinel), silicate minerals such as garnet (e.g., lithium garnet or lithium-containing garnet, of formula X3Z2(TO4)3 where X is Ca, Fe, etc., Z is Al, Cr, etc., T is Si, As, V, Fe, Al), lithium lanthanum zirconium oxide (LLZO), cordierite, mullite, perovskite (e.g., porous perovskite-structured ceramics), pyrochlore, silicon carbide, silicon nitride, boron carbide, sodium bismuth titanate, barium titanate (e.g., doped barium titanate), magnesium titanium oxide, barium neodymium titanate, titanium diboride, silicon alumina nitride, aluminum nitride, silicon nitride, aluminum oxynitride, reactive cerammed glass-ceramic (a glass ceramic formed by a combination of chemical reaction and devitrification, which includes an in situ reaction between a glass frit and a reactant powder(s)), silica, doped silica, ferrite (e.g., NiCuZnFeO ferrite, BaCO ferrite), lithium-containing ceramic, including lithium manganate, lithium oxide, viscous glasses as discussed above, such as high-melting temperature glasses, glasses with a Tg greater than 1000° C. at standard atmospheric pressure, high purity fused silica, silica with an SiO2 content of at least 99% by volume, silica comprising a granular profile, a silica tape without a repeating pattern of waves or striae extending across a width of the tape, iron sulfide, piezoelectric ceramic, potassium niobate, silicon carbide, sapphire, yttria, cermet, steatite, forsterite, lithium-containing ceramics (e.g., gamma-LiAlO2), transition metal oxide (e.g., lithium manganite, which may also be a spinel, ferrite), materials with volatile constituents as described above (e.g., lithium manganite (again)) lead oxide, garnets, alkali-containing materials, sodium oxide, glass-ceramic particles (e.g. LAS lithium aluminosilicates), and other inorganic materials as disclosed herein or otherwise.
In contemplated embodiments, inorganic binders like colloidal silica, alumina, zirconia, and hydrates thereof may be used in place of or in combination with organic binders as disclosed herein, such as to strengthen the tape. Applicants have found that stronger tape makes the sintering process more robust in terms of stability and access to a wider process space, such as greater tension. In some embodiments, a green material (e.g., green tape) as used herein, includes an inorganic binder. For example, a source of tape material may comprise a green tape and a carrier web supporting the green tape, the green tape comprising grains of inorganic material and an inorganic binder in an organic binder. In some embodiments, inorganic particles, such as inorganic binder includes particles of about 5 nm to about 100 micrometers in D50 particle size.
In contemplated embodiments, materials, such as ceramics disclosed herein, may be fired to have a high degree of porosity, such as greater than 20% by volume, such as greater than 50%, such as greater than 70%, and/or such materials may then be filled with a polymeric filler. Use of partially sintered inorganic material, as disclosed herein may have advantages over loose inorganic material in a composite because the partially sintered inorganic material may serve as a rigid skeleton to hold shape of the composite at high temperatures where the polymeric filler softens. Accordingly, some embodiments include a composite tape having dimensions disclosed above, of partially sintered ceramic, where (at least some, most, almost all) particles are the ceramic are sintered to one another and/or where porosity of the ceramic is at least partially, mostly, or fully filled with a polymer filler.
As indicated above, in some embodiments different inorganic materials may be co-fired using technology disclosed herein, such as discrete layers of the different inorganic materials (e.g., anode plus electrolyte of solid state battery), or in other arrangements, such as an evenly distributed mixture of two or more inorganic materials co-fired, such as to influence thermal expansion, strength, or other characteristics of the resulting article. In some embodiments, glass and ceramic may be co-fired, such as where a glass phase is mixed with particles of ceramic. For example,
Some embodiments of the present disclosure include an article (e.g., sheet, tape or ribbon), such as of inorganic material, such as ceramic, such as alumina or zirconia, with a granular profile and a layer (or coating) overlaying the granular profile to reduce roughness of the granular profile, such as on one or more major surfaces of the article. The layer may be applied in a liquid form through spin coating, slot die coating, spray coating, dip coating, or other processes. In some embodiments, the layer may be amorphous and inorganic, such as glass or converted into solid glass upon thermal annealing or curing. In some such embodiments, the layer is mostly silicon and oxygen, such as with some phosphorous, boron, carbon, nitrogen or other constituents. The layer may also include oxides of Ti, Hf, and/or Al. Such a layer may be applied and cured as part of the same manufacturing line as the binder burnout and sintering, and the resulting article (e.g., tape) may be rolled and include the layer when rolled. In some embodiments, the layer is annealed at temperatures of 850° C. or higher and is very thin, such as a positive thickness less than a micrometer, such as less than 560 nm. In some embodiments, roughness of the layer is less than half that of the granular profile, such as less than a third. In some embodiments, roughness of the layer is less than 15 nm, such as about 5 nm average roughness (Ra or Rq) over a distance of 1 cm along a single axis.
In yttrium-stabilized zirconia and alumina articles were laser cut into 30×30 mm squares and coated by spin-on-glass, spin coating techniques. A pure silica solution (Desert Silicon NDG series) was tested along with a lightly doped (1021 atoms/cm3) phosphorous-doped silica solution (Desert Silicon P-210). The solution was applied in a liquid form, and upon curing solidified. A final anneal densified the glass film. The solutions were applied using spin coating. Samples were then cured either in a hotplate at temperatures between 150° C. and 200° C. or in a vacuum oven with temperatures between 170° C. and 250° C. After the initial cure, samples were annealed in nitrogen atmosphere at temperatures between 850° C. and 1000° C. One-inch square silicon pieces were processed in parallel to the ceramic pieces to provide “witness” samples, used to accurately measure the glass film thickness using optical ellipsometer.
In one example a sheet of 40 μm thick alumina was coated with phosphorous-doped silica (Desert Silicon P210) by spinning at 1500 revolutions per minute (rpm) for 60 seconds, with 133 rpm/second acceleration, resulting in a coating of about 320 nm thick, 15.3 nm Ra, 12.1 nm Rq, 130 nm Zmax on one side and 25.9 nm Ra, 20 nm Rq, and 197 nm Zmax on the other, where the coated layer had good film quality after furnace anneal at 850° C., with no cracking. In another example a sheet of 40 μm thick alumina was coated with non-doped silica (Desert Silicon NDG-2000) by spinning at 1500 revolutions per minute (rpm) for 60 seconds, with 133 rpm/second acceleration, resulting in a coating of about 444 nm thick, 11 nm Ra, 8.8 nm Rq, 79.4 nm Zmax on one side and 22.6 nm Ra, 17 nm Rq, and 175 nm Zmax on the other, again where the coated layer had good film quality after furnace anneal at 850° C., with no cracking. By contrast, in another example a sheet of 40 μm thick alumina was coated with non-doped silica (Desert Silicon P210) by spinning at 4000 revolutions per minute (rpm) for 60 seconds, with 399 rpm/second acceleration, resulting in a coating of about 946 nm thick, 5.1 nm Ra, 6.5 nm Rq, 48 nm Zmax on one side and 10.8 nm Ra, 14 nm Rq, and 89 nm Zmax on the other, where the coated layer had pronounced cracking after furnace anneal at 850° C.
In one example a sheet of 40 μm thick yttria-stabilized zirconia was coated with non-doped silica (Desert Silicon NDG-2000) by spinning at 2000 revolutions per minute (rpm) for 60 seconds, with 1995 rpm/second acceleration, resulting in a coating of about 258 nm thick, 5.9 nm Ra, 4.7 nm Rq, 92 nm Zmax on one side, where the coated layer had good film quality after furnace anneal at 1000° C. for 60 minutes, with no cracking. In another example a sheet of 40 μm thick yttria-stabilized zirconia was coated with phosphorous-doped silica (Desert Silicon P210) by spinning at 1500 revolutions per minute (rpm) for 60 seconds, with 133 rpm/second acceleration, resulting in a coating of about 320 nm thick, 8.9 nm Ra, 11.7 nm Rq, 135 nm Zmax on one side, again where the coated layer had good film quality after furnace anneal at 850° C. for 30 minutes, with no cracking. By contrast, in another example a sheet of 40 μm thick yttria-stabilized zirconia was coated with non-doped silica (Desert Silicon P210) by spinning at 1500 revolutions per minute (rpm) for 60 seconds, with 133 rpm/second acceleration, resulting in a coating of about 444 nm thick, 7.7 nm Ra, 9.5 nm Rq, 75 nm Zmax on one side, where the coated layer had some cracking after furnace anneal at 850° C. Surface morphology of the samples was measured using Atomic-Force-Microscopy on a 10 micron field of view.
Aspects of the present disclosure relate to a sintered article that comprises (1) a first major surface, (2) a second major surface opposing the first major surface, and (3) a body extending between the first and second surfaces, where the body comprises a sintered inorganic material, where the body has a thickness (t) defined as a distance between the first major surface and the second major surface, a width defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width, and where the width is about 5 mm or greater, the thickness is in a range from about 3 μm to about 1 mm, and the length is about 300 cm or greater. This sintered article may be such that the inorganic material comprises an interface having a major interface dimension of less than about 1 mm, where the interface comprises either one of or both a chemical inhomogeneity and crystal structure inhomogeneity, and optionally where the inorganic material comprises a ceramic material or a glass ceramic material and/or where the inorganic material comprises any one of a piezoelectric material, a thermoelectric material, a pyroelectric material, a variable resistance material, or an optoelectric material. In some such embodiments, the inorganic material comprises one of zirconia, alumina, spinel, garnet, lithium lanthanum zirconium oxide (LLZO), cordierite, mullite, perovskite, pyrochlore, silicon carbide, silicon nitride, boron carbide, sodium bismuth titanate, barium titanate, titanium diboride, silicon alumina nitride, aluminum oxynitride, or a reactive cerammed glass-ceramic. In any one of the above sintered articles, the sintered article may comprise at least ten square centimeters of area along the length that has a composition where at least one constituent of the composition varies by less than about 3 weight %, across the area; and/or where the sintered article comprises at least ten square centimeters of area along the length that has a crystalline structure with at least one phase having a weight percent that varies by less than about 5 percentage points, across the area; and/or where the sintered article comprises at least ten square centimeters of area along the length that has a porosity that varies by less than about 20%; and/or where one or both the first major surface and the second major surface has a granular profile comprising grains with a height in a range from 25 nm to 150 μm relative to recessed portions of the respective surface at boundaries between the grains; and/or where one or both the first major surface and the second major surface has a flatness in the range of 100 nm to 50 μm over a distance of one centimeter along the length or the width; and/or where one of or both the first major surface and the second major surface comprises at least ten square centimeters of area having fewer than one hundred surface defects from adhesion or abrasion with a dimension greater than 5 μm, such as optionally where the other of the first major surface and the second major surface comprises surface defects from adhesion or abrasions with a dimension of greater than 5 μm; and/or further comprising a striated profile along the width dimensions, wherein the thickness is within a range from about 0.9 t to about 1.1 t, such as where the striated profile comprises 2 or more undulations along the width and/or where the striated profile comprises less than 20 undulations along the width.
Aspects of the present disclosure relate to a sintered article, comprising (1) a first major surface, (2) a second major surface opposing the first major surface, and (3) a body extending between the first and second surfaces, the body comprising a sintered inorganic material,
where the body has a thickness (t) defined as a distance between the first major surface and the second major surface, a width defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width, and where (at least) a portion of the sintered article is flattenable. In some such sintered articles, the article, when flattened, exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; and/or the article, when flattened, exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 1% of the Young's modulus of the article. In some such embodiments, where the article has a thickness of about 80 μm and a bend radius of greater than 0.03 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; or where the article has a thickness of about 40 μm and a bend radius of greater than 0.015 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; or where the article has a thickness of about 20 μm and a bend radius of greater than 0.0075 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article. In some such embodiments, the width of the sintered article is about 5 mm or greater, the thickness is in a range from about 3 μm to about 1 mm, and the length is about 300 cm or greater, and/or the portion of the sintered article that is flattenable comprises a length of about 10 cm. In some such embodiments, one or both the first major surface and the second major surface has a flatness in the range of 100 nm to 50 μm over a distance of one centimeter along the length or the width. In some such embodiments, the inorganic material comprises a ceramic material or a glass ceramic material; the inorganic material comprises any one of a piezoelectric material, a thermoelectric material, a pyroelectric material, a variable resistance material, or an optoelectric material; and/or the inorganic material comprises one of zirconia, alumina, spinel, garnet, lithium lanthanum zirconium oxide (LLZO), cordierite, mullite, perovskite, pyrochlore, silicon carbide, silicon nitride, boron carbide, sodium bismuth titanate, barium titanate, titanium diboride, silicon alumina nitride, aluminum oxynitride, or a reactive cerammed glass-ceramic. In some such embodiments, the sintered article comprises at least ten square centimeters of area along the length that has a composition where at least one constituent of the composition varies by less than about 3 weight %, across the area; and/or the sintered article comprises at least ten square centimeters of area along the length that has a crystalline structure with at least one phase having a weight percent that varies by less than about 5 percentage points, across the area; and/or the sintered article comprises at least 10 square centimeters of area along the length that has a porosity varies by less than about 20%, across the area; and/or one or both the first major surface and the second major surface has a granular profile comprising grains with a height in a range from 25 nm to 150 μm relative to recessed portions of the respective surface at boundaries between the grains; and/or one or both the first major surface and the second major surface has a flatness in the range of 100 nm to 50 μm over a distance of one centimeter along the length or the width; and/or one of or both the first major surface and the second major surface comprises have at least ten square centimeters of area having fewer than one hundred surface defects from adhesion or abrasion with a dimension greater than 5 μm, such as where the other of the first major surface and the second major surface comprises surface defects from adhesion or abrasions with a dimension of greater than 5 μm; and/or the sintered article further comprising a striated profile along the width dimensions, wherein the thickness is within a range from about 0.9 t to about 1.1 t, such as where the striated profile comprises 2 or more undulations along the width; and/or the article comprises a saddle shape; and/or the article comprises a c-shape having a concave shape along the length.
Aspects of the present disclosure relate to a rolled sintered article comprising (1) a core having a diameter of less than 60 cm and (2) a continuous sintered article wound around the core, the continuous sintered article comprising (2a) a first major surface, (2b) a second major surface opposing the first major surface, (2c) a body extending between the first and second surfaces, the body comprising a sintered inorganic material, where the body has a thickness (t) defined as a distance between the first major surface and the second major surface, a width defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width, and where the width is about 5 mm or greater, the thickness is in a range from about 3 μm to about 1 mm, and the length is about 30 cm or greater. In some such embodiments, the continuous sintered article is disposed on an interlayer support material, and the continuous sintered article and interlayer support material are wound around the core such that each successive wrap of the continuous sintered article is separated from one another by the interlayer support material, such as where the interlayer support material comprises a first major surface and a second major surface opposing the first major surface, an interlayer thickness (t) defined as a distance between the first major surface and the second major surface, an interlayer width defined as a first dimension of one of the first or second surfaces orthogonal to the interlayer thickness, and an interlayer length defined as a second dimension of one of the first or second major surfaces orthogonal to both the interlayer thickness and the interlayer width of the interlayer support material, and where the interlayer thickness is greater than the thickness of the sintered article and/or where the inlayer comprises a tension that is greater than a tension on the continuous sintered article, as measured by a load cell, and/or where the rolled article comprises a diameter and a side wall width that are substantially constant, and/or where the core comprises a circumference and a core centerline along the circumference, where the continuous sintered article comprises an article centerline along a direction of the length, and where distance between the core centerline and the article centerline is 2.5 mm or less, along the length of the continuous sintered article, and/or where the interlayer support material is compliant, and/or where the interlayer width is greater than the width of the continuous sintered article, and/or where the interlayer support material comprises any one or both a polymer and a paper, such as where the polymer comprises a foamed polymer, such as where the foamed polymer is closed cell.
Aspects of the present disclosure relate to a plurality of sintered articles each comprising (1) a first major surface, (2) a second major surface opposing the first major surface, and (3) a body extending between the first and second surfaces, the body comprising a sintered inorganic material, where the body has a thickness (t) defined as a distance between the first major surface and the second major surface, a width defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width, and where each of the plurality of sintered articles is flattenable. In some such embodiments, each article, when flattened, exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; and/or each article, when flattened, exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 10% of the Young's modulus of the article. In some such embodiments, where each article has a thickness of about 80 μm and a bend radius of greater than 0.03 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; and/or where each article has a thickness of about 40 μm and a bend radius of greater than 0.015 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; and/or where the article has a thickness of about 20 μm and a bend radius of greater than 0.0075 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article. In some such embodiments, the thickness of the plurality of sintered articles is within a range from about 0.7 t to about 1.3 t; and/or at least 50% of the sintered articles comprises an area and a composition, where at least one constituent of the composition varies by less than about 3 weight % across the area; and/or at least 50% the sintered articles comprise an area and a crystalline structure with at least one phase having a weight percent that varies by less than about 5 percentage points across the area; and/or at least 50% of the sintered articles comprise an area and a porosity that varies by less than about 20% across the area.
Aspects of the present disclosure relate to a separation system for separating two materials, where the separation system comprises a source of a continuous tape material comprising a green tape material and a carrier web supporting the green tape material; a vacuum drum positioned in proximity to the source of a continuous tape material and configured to receive and convey the continuous material from the source to a peeler, where the vacuum drum comprises a plurality of vacuum holes for facilitating applying tension by the separation system to the carrier web that is greater than a tension applied to the green tape material, as the continuous roll is conveyed to the peeler; and a peeler for directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction. In some such embodiments, the source of continuous tape material comprises a spool or a belt comprising the continuous material wound thereon. In some embodiments, the rewind and downstream processing directions form an angle therebetween that is greater than about 90 degrees. In at least some of such embodiments, the separation system applies essentially no tension to the green tape material (excluding weight of the green tape itself). In at least some of such embodiments, the tension applied to the carrier web at least 2 times greater than the tension applied to the green tape material. In at least some of such embodiments, the peeler comprises a tip that separates the carrier web from the green tape material before directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction. In at least some of such embodiments, the peeler comprises a tip that separates the carrier web from the green tape material simultaneously with directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction, where the tip may comprise a radius of about 0.05 inches or less. In at least some of such embodiments, the separation system further comprises a furnace for sintering the green tape material, an uptake reel for spooling the carrier web, and/or a load controller for maintaining the tension on the carrier web.
Other aspects of the present disclosure include a separation system for separating two materials, which comprises a source of a continuous tape material comprising a green tape material disposed on a carrier web, the carrier web comprising a first tension; a tension isolator positioned in proximity to the source configured to apply a second tension to carrier web that is greater than the first tension when conveying the continuous material to a peeler; and a peeler for directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction. In at least some of such embodiments (any one or more of the above embodiments), the source comprises a spool or a belt comprising the continuous material. In at least some of such embodiments, the rewind direction and the downstream processing direction form an angle that is greater than about 90 degrees. In at least some of such embodiments, the second tension is about 2.5 pounds per linear inch of width or less. In at least some of such embodiments, the first tension is equal to or less than about 50% of the second tension. In at least some of such embodiments, the peeler comprises a tip that separates the carrier web from the green tape material before directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction; and/or the tip that separates the carrier web from the green tape material simultaneously with directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction; where in neither, either, or both such embodiments the tip comprises a radius of about 0.05 inches or less. In at least some of such embodiments, the tension isolator comprises a vacuum drum comprising a plurality of vacuum holes that apply the second tension to the carrier web. In at least some of such embodiments, the separation system further comprises a furnace for sintering the green tape material, an uptake reel for spooling the carrier web, and/or a load controller for maintaining the tension on the carrier web.
Aspects of the present disclosure relate to a method for separating two materials, the method comprising steps, not necessarily in the following order, of (1) feeding a continuous material to a tension isolator, the continuous material comprising a green tape material disposed on a carrier web, (2) applying tension to the carrier web that is greater than a tension applied to the green tape material with the tension isolator, and (3) directing the carrier web to move in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction. In at least some such embodiments, the method further comprises a step of separating the carrier web from the green tape material before directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction, and/or separating the carrier web from the green tape material simultaneously with directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction, such as where the rewind direction and the downstream processing direction form an angle that is greater than about 90 degrees. In at least some such embodiments, the method further comprises a step of applying essentially no tension to the green tape material, such as where the tension applied to the carrier web at least 2 times greater than the tension applied to the green tape material. In at least some such embodiments, the method further comprises a step of at least partially sintering the green tape material. In at least some such embodiments, the method further comprises a step of spooling the carrier web onto an uptake reel. In at least some such embodiments, the method further comprises a step of maintaining the tension on the carrier web.
Aspects of the present disclosure relate to a method for separating two continuous materials, where the method comprises steps, not necessarily in the following order, of (1) feeding a continuous tape material comprising a green tape supported on a carrier web to a tension isolator and applying a first tension to the carrier web; (2) applying a second tension to the carrier web that is greater than the first tension; and (3) directing the carrier web to move in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction. In at least some such embodiments, the method further comprises a step of separating the carrier web from the green tape material before directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction and/or separating the carrier web from the green tape material simultaneously with directing the carrier web in a rewind direction and directing the green tape material in a downstream processing direction that differs from the rewind direction, such as where the rewind direction and the downstream processing direction form an angle that is greater than about 90 degrees. In at least some such embodiments, the method further comprises a step of applying a first tension comprises applying essentially no tension (i.e. very little as disclosed herein). In at least some such embodiments, the second tension is about 2.5 pounds per linear inch of width or less. In at least some such embodiments, the first tension is equal to or less than about 50% of the second tension. In at least some such embodiments, the method further comprises a step of at least partially sintering the green tape material, spooling the carrier web onto an uptake reel, and/or maintaining the tension on the carrier web.
Aspects of the present disclosure relate to a roll-to-roll tape sintering system, the system comprising (1) an input roll of a length of tape material comprising grains of inorganic material, the inorganic material of the tape material on the input roll having a first porosity; (2) a sintering station comprising (2a) an entrance, (2b) an exit, (2c) a channel extending between the entrance and the exit, and (2d) a heater heating the channel to a temperature greater than 500 degrees C., where the exit, the entrance, and the channel of the sintering station lie in a substantially horizontal plane, such that an angle defined between the exit and the entrance relative to a horizontal plane is less than 10 degrees, and where the tape material passes from the input roll, into the entrance of the sintering station, through the channel of the sintering station and out of the exit of the sintering station and heat within the channel sinters the inorganic material of the tape material; and (3) an uptake roll winding the length of tape material following exit from the sintering station, where the inorganic material of the tape material on the uptake roll has a second porosity that is less than the first porosity. In at least some such embodiments, the angle defined between the exit and the entrance relative to a horizontal plane is less than 1 degree. In at least some such embodiments, the tape material on the input roll has a width greater than 5 mm and a length greater than 10 m. In at least some such embodiments, the tape material on the input roll has a thickness between 3 microns and 1 millimeter. In at least some such embodiments, the tape material moves through the sintering station at a high speed of greater than 6 inches per minute. In at least some such embodiments, the tape material on the input role includes an organic binder material supporting the grains of inorganic material, and the system further comprises (4) a binder removal station located between the input roll and the sintering station, the binder removal station comprising (4a) an entrance, (4b) an exit, (4c) a channel extending between the entrance and the exit, and (4d) a heater heating the channel to a temperature between 200 degrees C. and 500 degrees C., wherein the exit of the binder station, the entrance of the binder station, and the channel of the binder station lie in a substantially horizontal plane such that an angle defined between the exit of the binder station and the entrance of the binder station relative to a horizontal plane is less than 10 degrees, where the channel of the binder station is aligned with the channel of the sintering station such that the tape material passes from the input roll, into the entrance of the binder removal station, through the channel of the binder removal station and out of the exit of the binder removal station into the entrance of the sintering station while moving in a substantially horizontal direction, where heat within the channel of the binder removal station chemically changes and/or removes at least a portion of the organic binder material prior to the tape material entering the sintering station. In at least some such embodiments, the heater of the sintering station includes at least two independently controlled heating elements, the heating elements generate a temperature profile along the length of the channel of the sintering station that increases along the channel in a direction from the entrance toward the exit; where in some such embodiments the temperature profile is shaped such that stress at edges of the tape material during sintering remains below an edge stress threshold and such that stress at a centerline of the tape material during sintering remains below a centerline stress threshold, where the edge stress threshold and the centerline stress threshold are defined as those stresses above which the tape material experiences out of plane deformation at the edge and centerline, respectively, of greater than 1 mm, such as where the edge stress threshold is less than 300 MPa and the centerline stress threshold is less than 100 MPa. In at least some such embodiments, the channel of the sintering station is at least 1 m long. In at least some such embodiments, the sintering station comprises (2d-i) a first sintering furnace defining a first portion of the sintering station channel extending from the entrance of the sintering station to an exit opening of the first sintering furnace, (2d-ii) a second sintering furnace defining a second portion of the sintering station channel extending from an entrance opening of the second sintering furnace to the exit of the sintering station, and (2e) a tension control system located between the first sintering furnace and the second sintering furnace, the tension control system helping to isolate tension between the first and second sintering furnaces, wherein tension in the tape material within the second sintering furnace that is greater than a tension within the tape material in the first sintering furnace. In at least some such embodiments, the sintering station comprises (2f) an upward facing channel surface defining a lower surface of the channel and (2g) a downward facing channel surface defining an upper surface of the channel, where a lower surface of the tape material is in contact with and slides along the upward facing surface as the tape material moves from the entrance to the exit of the sintering station, where the downward facing channel surface is positioned close to an upper surface of the tape material such that a gap between the upper surface of the tape material and the downward facing channel surface is less than 0.5 inches, where at least a portion of the upward facing channel surface is substantially horizontal measured in the direction between the entrance and exit of the sintering station such that the portion of the upward facing channel surface forms an angle of less than 3 degrees relative to the horizontal plane. In at least some such embodiments, the inorganic material of the tape is at least one of a polycrystalline ceramic material and synthetic mineral.
Aspects of the present disclosure include a manufacturing furnace comprising (1) a housing having an upstream face and a downstream face, (2) an entrance opening formed in the upstream face, (3) an exit opening defined in the downstream face, (4) an upward facing surface located between the entrance opening and the exit opening, (5) a downward facing flat surface located between the entrance opening and the exit opening, (6) a heating channel extending between the entrance opening and the exit opening and defined between the upward facing surface and the downward facing surface, (7) a continuous length of tape extending into the entrance opening, through the heating channel and out of the exit opening, the continuous length of tape comprising: (7a) grains of inorganic material, (7b) a left edge extending through the heating channel the entire distance between the entrance opening and the exit opening, (7c) a right edge extending through the heating channel the entire distance between the entrance opening and the exit opening, and (7d) a centerline parallel to and located between the left edge and the right edge; and (8) a plurality of the independently controlled heating elements delivering heat to the heating channel generating a temperature profile along the length of the heating channel, the temperature profile having temperatures greater than 500 degrees C. sufficient to cause shrinkage of the inorganic material of the tape as the tape moves through the heating channel, where the temperature profile increases gradually along at least a portion of the length of the heating channel such that the stress within the tape during shrinkage at the left and right edge remain below an edge stress threshold along the entire length of the heating channel or stress within the tape material measured at the centerline remain below a centerline stress threshold along the entire length of the heating channel. In at least some such embodiments, the edge stress threshold is less than 100 MPa and the centerline stress threshold is less than 100 MPa. In at least some such embodiments, the continuous length of tape has an average width greater than 5 mm. In at least some such embodiments, the entrance opening and the exit opening are aligned with each other in the vertical direction such that a straight line located along the upward facing surface forms an angle relative to a horizontal plane that is less than 10 degrees. In at least some such embodiments, the continuous length of tape moves in a direction from the entrance to the exit and the lower surface of the tape moves relative to the upward facing surface, such as where the lower surface of the tape is in contact with and slides relative to the upward facing surface. In at least some such embodiments, the temperature profile includes a first section having a first average slope, a second section having second average slope and a third section have a third average slope, where the first average slope is greater than the second average slope, and where the first and second average slopes are positive slopes and the third average slope is a negative slope, such as where the first, second and third sections are directly adjacent with one another and in numerical order, and most or all of the temperature profile; for example, in at least some such embodiments, the second section has a minimum temperature that is greater than 500 degrees C. and a maximum temperature that is less than 3200 degrees C., and extends from the minimum temperature to the maximum temperature over a length of at least 50 inches. In at least some such embodiments, the heating channel is narrow, such that at a cross-section along the length thereof the maximum vertical distance between the upward facing surface and the downward facing surface is less than one inch. In at least some such embodiments, the heating channel is divided into at least a first heating section and second heating section, where a tension control system is located between the first heating section and the second heating section, where the tension control system at least in part isolates tension in the tape such that tension in the tape material within the second heating section that is greater than tension within the tape material in the first heating section. In at least some such embodiments, the inorganic material of the tape is at least one of a polycrystalline ceramic material and synthetic mineral.
Aspects of the present disclosure relate to a process for forming a spool of sintered tape material comprising steps, not necessarily in the following order, of (1) unwinding a tape from an input reel, the tape comprising grains of inorganic material and a width greater than 5 mm, (2) moving the unwound length of tape through a heating station, (3) heating the tape within the heating station to a temperature above 500 degrees C. such that the inorganic material of the tape is sintered as it moves through the heating station, and (4) winding the tape on an uptake reel following heating and sintering. In at least some such embodiments, the tape material is held in a substantially horizontal position during heating. In at least some such embodiments, the tape material on the input reel further comprises an organic binder material supporting the grains of inorganic material, the process further comprising heating the tape material to a temperature between 200 degrees C. and 500 degrees C. to remove the binder material before the step of heating the tape material to a temperature above 500 degrees C. In at least some such embodiments, the width of tape material is greater than 10 mm and the length of the tape material is greater than 10 m. In at least some such embodiments, the tape material is unwound at a speed of at least 6 inches per minute. In at least some such embodiments, the inorganic material is at least one of a polycrystalline ceramic material and synthetic mineral.
Aspects of the present disclosure relate to a manufacturing system that comprises a tape advancing through the manufacturing system, the tape including a first portion having grains of an inorganic material bound by an organic binder; and a station of the manufacturing system that receives the first portion of the tape and prepares the tape for sintering by chemically changing the organic binder and/or removing the organic binder from the first portion of the tape, leaving the grains of the inorganic material, to form a second portion of the tape and thereby at least in part prepare the tape for sintering. In at least some such embodiments, at an instant, the tape simultaneously extends to, through, and from the station such that at the instant the tape includes the first portion continuously connected to the second portion. In at least some such embodiments, the station chars or burns at least most of the organic binder, in terms of weight, from the first portion of the tape without substantially sintering the grains of the inorganic material. In at least some such embodiments, the station comprises an active heater to char or burn at least most of the organic binder from the first portion of the tape as the tape interfaces with the station to form the second portion of the tape, such as where the active heater includes heating zones of different temperatures, such as where the rate of heat energy received by the tape increases as the tape advances through the station. In at least some such embodiments, the station is a first station and the manufacturing system further comprises a second station, where the second station at least partially sinters the inorganic material of the second portion of the tape to form a third portion of the tape, such as where, at an instant, the tape includes the first portion continuously connected to the third portion byway of the second portion, and/or such as where the first station is close to the second station such that distance between the first and second stations is less than 10 m, thereby mitigating thermal shock of the second portion of the tape. In at least some such embodiments, the second portion of the tape is under positive lengthwise tension as the tape advances, such as where the lengthwise tension in the second portion of the tape is less than 500 grams-force per mm2 of cross section. In at least some such embodiments, the manufacturing system blows and/or draws gas over the tape as the tape advances through the station, such as where the station heats the tape above a temperature at which the organic binder would ignite without the gas blown and/or drawn over the tape, whereby the organic binder chars or burns but the tape does not catch fire, and/or such as where flow of the gas blown and/or drawn over the tape as the tape advances through the station is laminar at least over the second portion of the tape. In at least some such embodiments, the tape advances horizontally through the station, and in some such embodiments the tape is directly supported by a gas bearing and/or an underlying surface and moves relative to that surface as the tape advances through the station. In at least some such embodiments, the first portion of the tape is substantially more bendable than the second portion such that a minimum bend radius without fracture of the first portion is less than half that of the second portion.
Aspects of the present technology relate to a furnace to prepare green tape for sintering the furnace comprising walls defining a passage having inlet and outlet openings on opposing ends of the passage, where the passage has a length between the inlet and outlet openings of at least 5 cm, and where the outlet opening is narrow and elongate, having a height and a width orthogonal to the height, wherein the height is less than a fifth of the width, and wherein the height is less than 2 cm; and the furnace further includes a heater that actively provides heat energy to the passage, where the heater reaches temperatures of at least 200° C. In at least some such embodiments, the furnace is further comprising a gas motivator that blows and/or draws gas through the passage, such as where the gas motivator delivers at least 1 liter of gas per minute through the passage. In at least some such embodiments, the passage is horizontally oriented, as described above. In at least some such embodiments, the heater comprises heat zones that increase temperature along the passage with distance from the inlet toward the outlet.
Aspects of the present technology relate to a method of processing tape, comprising steps of (1) advancing a tape through a manufacturing system, the tape including a first portion having grains of an inorganic material bound by an organic binder; and (2) preparing the tape for sintering by forming a second portion of the tape at a station of the manufacturing system by chemically changing the organic binder and/or removing the organic binder from the first portion of the tape, leaving the grains of the inorganic material. In at least some such embodiments, at an instant, the tape extends to, through, and from the station such that at the instant the tape includes the first portion continuously connected to the second portion. In at least some such embodiments, the step of preparing the tape for sintering further comprises charring or burning at least most of the organic binder from the first portion of the tape without (substantially) sintering the grains of the inorganic material. In at least some such embodiments, the first portion of the tape is substantially more bendable than the second portion such that a minimum bend radius without fracture of the first portion is less than half that of the second portion. In at least some such embodiments, the station of the manufacturing system is a first station and the method of processing further comprises steps of receiving the second portion of the tape at a second station, and at least partially sintering the inorganic material of the second portion of the tape at the second station to form a third portion of the tape, such as in at least some such embodiments, at an instant, the tape includes the first portion continuously connected to the third portion by way of the second portion. In at least some such embodiments, the process further comprises a step of positively tensioning the second portion of the tape as the tape advances, such as where the step of positively tensioning is such that lengthwise tension in the second portion of the tape is less than 500 grams-force per mm2 of cross section. In at least some such embodiments, the process further comprises a step of blowing and/or drawing gas over the tape as the tape advances through the station. In at least some such embodiments, the step of advancing the tape further comprises horizontally advancing the tape through the station. In at least some such embodiments, the process further comprises a step of directly supporting the tape by a gas bearing and/or an underlying surface and moving the tape relative to that surface.
Aspects of the present disclosure relate to package comprising: a substrate; a sintered article comprising a body extending between a first major surface and a second major surface;
the body comprises a sintered inorganic material, a thickness (t) defined as a distance between the first major surface and the second major surface, a width defined as a first dimension of one of the first or second surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second surfaces orthogonal to both the thickness and the width; and the sintered article joined directly or indirectly to the substrate. In some such embodiments, the body width is about 5 mm or greater, the body thickness is in a range from about 3 μm to about 1 mm, and the body length is about 300 cm or greater. In some such embodiments, the a portion of the sintered article is flattenable, such as where the sintered article, when flattened, exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article and/or such as where the sintered article, when flattened, exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 1% of the Young's modulus of the article. In some such embodiments, the sintered article has a thickness of about 80 μm and a bend radius of greater than 0.03 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; or the sintered article has a thickness of about 40 μm and a bend radius of greater than 0.015 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article; or the sintered article has a thickness of about 20 μm and a bend radius of greater than 0.0075 m, the article exhibits a maximum in plane stress (the absolute value of stress, as measured by the thin plate bend bending equation) of less than or equal to 25% of the bend strength (measured by 2-point bend strength) of the article. In some such embodiments, a portion of the sintered article that is flattenable comprises a length of about 10 cm. In some such embodiments, one or both the first major surface and the second major surface of the sintered article has a flatness in the range of one hundred nanometers to fifty micrometers over a distance of one centimeter along the length or the width. In some such embodiments, the sintered inorganic material comprises an interface having a major interface dimension of less than about 1 mm, wherein the interface comprises either one of or both a chemical inhomogeneity and crystal structure inhomogeneity. In some such embodiments, the sintered inorganic material comprises a ceramic material or a glass ceramic material. In some such embodiments, the sintered inorganic material comprises any one of a piezoelectric material, a thermoelectric material, a pyroelectric material, a variable resistance material, or an optoelectric material. In some such embodiments, the sintered inorganic material comprises one of zirconia, alumina, yttria stabilized zirconia (YSZ), spinel, garnet, lithium lanthanum zirconium oxide (LLZO), cordierite, mullite, perovskite, pyrochlore, silicon carbide, silicon nitride, boron carbide, sodium bismuth titanate, barium titanate, titanium diboride, silicon alumina nitride, aluminum oxynitride, or a reactive cerammed glass-ceramic. In some such embodiments, the sintered article comprises at least ten square centimeters of area along the length that has a composition wherein at least one constituent of the composition varies by less than about 3 weight % across the area. In some such embodiments, the sintered article comprises at least ten square centimeters of area along the length that has a crystalline structure with at least one phase having a weight percent that varies by less than about 5 percentage points, across the area. In some such embodiments, the sintered article comprises at least ten square centimeters of area along the length that has a porosity varies by less than about 20%. In some such embodiments, the one or both the first major surface and the second major surface of the sintered article has a granular profile comprising grains with a height in a range from 25 nm to 150 μm relative to recessed portions of the respective surface at boundaries between the grains. In some such embodiments, the one or both the first major surface and the second major surface of the sintered article has a flatness in the range of 100 nm to 50 μm over a distance of one centimeter along the length or the width. In some such embodiments, the one of or both the first major surface and the second major surface of the sintered article comprises have at least ten square centimeters of area having fewer than one hundred surface defects from adhesion or abrasion with a dimension greater than 5 μm. In some such embodiments, the other of the first major surface and the second major surface of the sintered article comprises surface defects from adhesion or abrasions with a dimension of greater than 5 μm, such as due to sliding along a surface of the furnace during sintering. In some such embodiments, the substrate comprises an electrically conductive metal. In some such embodiments, the substrate comprises aluminum, copper, or combinations thereof. In some such embodiments, the substrate comprises a compliant polymer material. In some such embodiments, the substrate comprises a polyimide. In some such embodiments, the sintered article joined directly or indirectly to the substrate is rolled around a core at least once, the core having a diameter of less than 60 cm. In some such embodiments, the package is further comprising an interlayer that joins the sintered article and the substrate, such as where the interlayer has a thickness less than 40 μm and/or where the substrate comprises grooves that contact the interlayer. In some such embodiments, the package is further comprising a metal-based layer on at least a portion of one or both the first major surface and the second major surface of the sintered article, such as where the metal-based layer comprises copper, nickel, gold, silver, gold, brass, lead, tin, or combinations thereof and/or where the metal-based layer and the substrate are joined to same major surface of the sintered article, and/or where the metal-based layer is joined to the sintered article through an aperture in the substrate. In some such embodiments, the package is further comprising a semiconductor device electrically connected to the metal-based layer, such as where light that emanates from an LED on the semiconductor device transmits through the body thickness of the sintered article, and/or wherein the sintered article has a thermal conductivity greater than 8 W/m K.
Additional aspects of the present disclosure relate to method of making some or all of the packages just described, the method comprising a step of joining the substrate directly or indirectly to the first or second major surface of the sintered article. In some such embodiments, the substrate comprises a compliant polymer material. In some such embodiments, the substrate comprises an electrically conductive metal. In some such embodiments, the method further comprises applying a precursor interlayer to one or both of the substrate and the sintered article, the precursor interlayer joins the substrate and the sintered article. In some such embodiments, the method further comprises thermally deactivating the temporary adhesive to separate the substrate from the sintered article. In some such embodiments, the method further comprises bonding a metal-based layer on at least a portion of one or both the first major surface and the second major surface of the sintered article, and the method may further comprise electrically connecting a semiconductor device to the metal-based layer.
Aspects of the present disclosure relate to a process for forming a sintered tape material comprising steps of (1) moving a tape toward a heating station, the tape comprising grains of inorganic material, (2) coupling a first section of a threading material to a leading section of the tape, (3) pulling both the first section of threading material and the leading section of the tape through the heating station by applying a force to a second section of the threading material located outside of the heating station, and (4) heating at least a portion of the tape within the heating station to a temperature above 500 degrees C. such that the inorganic material of the tape is sintered as it moves through the heating station. In some such embodiments, the heating station has an entrance and an exit, and the process is further comprising a step of positioning the threading material such that the threading material extends through the heating station, that the first section of the threading material is located upstream from the entrance and that a second section of threading material is located downstream from the exit, where the coupling step occurs after the positioning step. In some such embodiments, the threading material is an elongate strip of material that is different from the inorganic material of tape, such as where the difference between the threading material and the inorganic material of tape is at least one of a different material type and different degree of sintering, and/or where the leading section of the tape overlaps the first section of the threading material such that a lower surface of the tape contacts an upper surface of the threading material. In some such embodiments, the coupling step comprises bonding the threading material to the tape via an adhesive material, such as where a coefficient of thermal expansion of the threading material is within plus or minus 50% of a coefficient of thermal expansion of the inorganic material of the tape and is within plus or minus 50% of a coefficient of thermal expansion of the adhesive material, and/or where the inorganic material of the tape is at least one of a polycrystalline ceramic material and synthetic mineral, where the adhesive material is a ceramic containing adhesive material, and where the threading material is at least one of a sintered ceramic material and a metal material. In some such embodiments, the step of moving the tape toward the heating station includes unwinding the tape from an input reel, where the second section of the threading material is coupled to an uptake reel, and the force is generated by rotation of the uptake reel. In some such embodiments, the process further comprises a step of continuing to move the tape through a heating station following unwinding from the input reel forming a length of sintered inorganic material of the tape; and another step of winding the tape on an uptake reel following heating and sintering, such as where the tape is held in a substantially horizontal position during heating, such as where the tape on the input reel further comprises an organic binder material supporting the grains of inorganic material, and the process further comprises heating the tape to a temperature between 200 degrees C. and 500 degrees C. to remove the binder material before the step of heating the tape to a temperature above 500 degrees C.
Aspects of the present disclosure relate to a process for forming a spool of sintered tape material comprising steps of (1) unwinding a tape from an input reel, the tape comprising grains of inorganic material; (2) moving a threading material through a channel of a heating station in a direction from an exit of the heating station toward an entrance of the heating station such that a first section of a threading material extends out of the entrance of the heating station; (3) coupling the first section of the threading material to the tape; (4) coupling a second section of the threading material to an uptake reel located downstream from the exit of the heating station; (5) rotating the uptake reel such that tension is applied to the threading material by the uptake reel which in turn is applied to the tape pulling the tape through the heating station; (6) heating at least a portion of the tape within the heating station to a temperature above 500 degrees C. such that the inorganic material of the tape is sintered as it moves through the heating station; and (7) winding the tape on an uptake reel following heating and sintering. In some such embodiments, at least one of: (i) the threading material and the inorganic material of tape are different from each other and (ii) a degree of sintering of the threading material is greater than a degree of sintering of the inorganic material of the tape on the input reel. In some such embodiments, the leading section of the tape overlaps the first section of the threading material such that a lower surface of the tape contacts an upper surface of the threading material, and the coupling step comprises bonding the threading material to the tape via an adhesive material.
Aspects of the present technology relate to a roll to roll tape sintering system comprising (1) an input roll of a length of tape material comprising grains of inorganic material, the inorganic material of the tape material on the input roll having a first porosity; (2) a sintering station comprising: (2a) an entrance; (2b) an exit; (2c) a channel extending between the entrance and the exit; and (2d) a heater heating the channel to a temperature greater than 500 degrees C., where wherein the tape material extends from the input roll toward the entrance of the sintering station, where heat within the channel causes sintering of the inorganic material of the tape material; (3) an uptake roll winding the length of tape material following exit from the sintering station; and (4) a length of threading material extending through the exit and out of the entrance of the sintering station, wherein a first end section of the threading material is coupled to a leading section of the tape material before the entrance of the sintering station and a second end section of the threading material is wrapped around the uptake roll such that tension applied to the threading material by winding of the uptake roll is applied to the tape material. In some such embodiments, at least one of: (i) the threading material and the inorganic material of tape material are different from each other and (ii) a degree of sintering of the threading material is greater than a degree of sintering of the inorganic material of the tape on the input roll. In some such embodiments, the leading section of the tape material overlaps the first section of the threading material such that a lower surface of the tape material contacts an upper surface of the threading material, and the threading material is coupled to the tape material via a bond formed by an adhesive material, such as where the inorganic material is at least one of a polycrystalline ceramic material and synthetic mineral, where the adhesive material is a ceramic adhesive material, and where the threading material is at least one of a sintered ceramic material and a metal material. In some such embodiments, the exit, the entrance and the channel of the sintering station lie in a substantially horizontal plane, such that an angle defined between the exit and the entrance relative to a horizontal plane is less than 10 degrees.
Aspects of the present disclosure relate to a process for forming a sintered tape material comprising steps of (1) unwinding a tape from an input reel, the tape comprising grains of inorganic material, wherein the tape on the input reel has an average thickness between 1 micron and 1 millimeter; (2) moving the unwound length of tape through a heating station along a path having a first curved section such that the tape is bent through a radius of curvature of 0.01 m to 13,000 m; (3) heating the tape within the heating station to a temperature above 500 degrees C. while the unwound length of tape is bent through the radius of curvature, wherein the inorganic material of the tape is sintered as it moves through the heating station; and (4) winding the tape on a take-up reel following heating and sintering. In contemplated embodiments, such a process may be broader, and may not include the unwinding and/or the winding steps. In some such embodiments, the heating station includes a lower surface and an upper surface defining a channel extending between an entrance and an exit of the heating station, where the lower surface includes a convex curved surface extending in a longitudinal direction between the entrance and the exit, wherein the convex curved surface defines the first curved section of the path. In some such embodiments, the upper surface includes a concave curved surface matching the convex curved surface of the lower surface such that a height of the channel remains constant along at least a portion of a length of the channel. In some such embodiments, the convex curved surface is an upper surface of a gas bearing, and the gas bearing delivers pressurized gas to the channel to support the tape above the convex curved surface as the tape moves through the heating station. In some such embodiments, the convex curved surface is continuous curved surface the extends an entire longitudinal length between the entrance and the exit, wherein a maximum rise of the convex curved surface is between 1 mm and 10 cm. In some such embodiments, the path through the heating station has a second curved section having a radius of curvature of 0.01 m to 13,000 m, where the tape is heated within the heating station to a temperature above 500 degrees C. while the unwound length of tape is bent through the radius of curvature of the second curved section, such as where the tape is heated to a first temperature when the tape traverses the first curved section and is heated to a second temperature, different from the first temperature, when the tape traverses the second curved section. In some such embodiments, the first curved section of the path is defined by a free loop segment in which the tape hangs under the force of gravity between a pair of supports to form the radius of curvature in the tape. In some such embodiments, the heating station has a convex curved surface located therein defining the first curved section of the path, and the process further comprises a step of applying tension to the tape such that the tape bends into conformity with the convex curved surface, such as where the convex curved surface is an outer surface of at least one of a mandrel and a roller. In some such embodiments, the tape is moved through the heating station at a speed of between 1 inch and 100 inches of tape length per minute. In some such embodiments, tension is applied to the tape in a longitudinal direction, where the tape has a width and the tension is at least 0.1 gram-force per linear inch of width of the tape. In some such embodiments, the inorganic material of the tape is at least one of a polycrystalline ceramic material and synthetic mineral.
Aspects of the present disclosure relate to a process for forming a sintered tape material comprising steps of (1) moving a contiguous length of tape through a heating station such that a first portion of the contiguous length of tape is located upstream from an entrance of the heating station, a second portion of the contiguous length of tape is located downstream from an exit of the heating station, and a third portion of the contiguous length of tape is located between the first portion and the second portion, the contiguous length of tape comprising grains of inorganic material, (2) heating the third portion of the contiguous length of tape within the heating station to a temperature above 500 degrees C. such that the inorganic material is sintered within the heating station, and (3) bending the third portion of the contiguous length of tape to a radius of curvature of 0.01 m to 13,000 m while at the temperature above 500 degrees C. within the heating station. In at least some such embodiments, the bending includes applying a longitudinally directed force to the contiguous length of tape such that third portion bends around a curved surface located within the heating station. In at least some embodiments, the contiguous length of tape is unrolled from an input reel, the contiguous length of tape is moved continuously and sequentially through the heating station such that entire contiguous length of the tape experiences bending to the radius of curvature of 0.01 m to 13,000 m while moving through the heating station, and where the contiguous length of tape is rolled onto a take-up reel following bending and heating.
Aspects of the present disclosure relate to a roll-to-roll tape sintering system comprising (1) an input roll of a length of tape material comprising grains of inorganic material, the inorganic material of the tape material on the input roll having a first porosity; (2) a sintering station comprising: (2a) an entrance; (2b) an exit; (2c) a channel extending between the entrance and the exit; (2d) a heater heating the channel to a temperature greater than 500 degrees C.; where the tape material passes from the input roll, into the entrance of the sintering station, through the channel of the sintering station and out of the exit of the sintering station and the heat within the channel causes sintering of the inorganic material of the tape material; (3) a bending system located within the sintering station inducing a radius of curvature along a longitudinal axis of the tape material as the tape material passes through the heating station, wherein the radius of curvature is 0.01 m to 13,000 m; and (4) a take-up roll winding the length of tape material following exit from the sintering station; where the inorganic material of the tape material on the take-up roll has a second porosity that is less than the first porosity. In some such embodiments, the exit and the entrance lie in a substantially horizontal plane such that an angle defined between the exit and the entrance relative to a horizontal plane is less than 10 degrees, wherein the bending system includes a convex curved surface located along a path between the entrance and the exit, wherein the tape is bent around the convex curved surface as the tape moves through the heating station, wherein the convex curved surface defines the radius of curvature and is curved around an axis parallel to a width axis of the tape material. In some such embodiments, the convex curved surface is an outer surface of at least one of a mandrel and a roller and/or the convex curved surface is a lower surface of the sintering station that defines the channel of the sintering station, such as where the convex curved surface forms a continuous curve that extends the entire length of the channel from the entrance to the exit of the sintering station. In some such embodiments, the convex curved surface is an upper surface of a gas bearing that delivers gas to the channel supporting the tape within the channel without contacting the convex curved surface. In other such embodiments, the bending system includes a pair of support structures located with the sintering station, wherein the support structures are spaced from each other forming a gap and the tape sags downward due to gravity between the support structures to form the radius of curvature.
Aspects of the present disclosure relate to a roll-to-roll tape sintering system comprising (1) an input roll of a length of tape material comprising grains of inorganic material, the inorganic material of the tape material on the input roll having a first porosity; (2) a sintering station comprising: (2a) an entrance; (2b) an exit; (2c) a channel extending between the entrance and the exit having a longitudinal length, L, wherein a lower surface of the channel is defined by a continuously curved surface extending the longitudinal length L and having a radius of curvature, R, and a maximum rise, H; wherein R=H+(L{circumflex over ( )}2)/H; wherein 0.1 mm<H<100 mm, and 0.1 m<L2<100 m; (3) a heater heating the channel to a temperature greater than 500 degrees C.; wherein the tape material passes from the input roll, into the entrance of the sintering station, through the channel of the sintering station and out of the exit of the sintering station and the heat within the channel causes sintering of the inorganic material of the tape material; and (4) a take-up roll winding the length of tape material following exit from the sintering station, wherein the inorganic material of the tape material on the take-up roll has a second porosity that is less than the first porosity.
Some aspects of the present disclosure relate to a tape separation system for sintering preparation by separating parts of the tape from one another, as disclosed above and discussed with regard to
Other aspects of the present disclosure relate to a system for processing tape for sintering preparation, as shown and discussed with regard to
Additional aspects of the present disclosure relate to a manufacturing line comprising the above system for processing tape, where the binder burnout station is a first station and the manufacturing line further comprises a second station spaced apart from the first station. The second station may be spaced apart from the first station as shown in
Some aspects of the present disclosure relate to a sintering system comprising a tape material comprising grains of inorganic material and a sintering station, such as discussed above with regard to
Other aspects of the present disclosure relate to a process for manufacturing ceramic tape, the process comprising a step of sintering tape comprising polycrystalline ceramic to a porosity of the polycrystalline ceramic of less than 20% by volume, by exposing particles of the polycrystalline ceramic to a heat source to induce the sintering between the particles. The tape is particularly thin such that a thickness of the tape is less than 500 μm, thereby facilitating rapid sintering via heat penetration. Further, the tape is at least 5 mm wide and at least 300 cm long. In some embodiments, the process further includes a step of positively lengthwise tensioning the tape during the sintering. In some such embodiments, the process further includes a step of moving the tape toward and then away from the heat source during the sintering, such as through the channel of the sintering station. In some embodiments, the amount of time of the sintering is particularly short, that being less than two hours in aggregate for any particular portion of the tape, thereby helping to maintain small grain size in the ceramic tape, improving strength, reducing porosity, saving energy; for example, in some such embodiments, the time in aggregate of the sintering is less than one hour, such as compared to 20 hour for conventional batch sintering, and density of the polycrystalline ceramic after the sintering is greater than 95% dense by volume and/or the tape comprises closed pores after the sintering, no pin holes, few surface defects, geometric consistency, etc. In some embodiments, the tape comprises a volatile constituent that vaporizes during the sintering, such as lithium, where the volatile constituent is inorganic, and where the tape comprises at least 1% by volume (e.g., at least 5%, at least 10%, and/or no more than 200%, such as no more than 100% by volume) more of the volatile constituent prior to the sintering than after the sintering. While some of the volatile constituent may vaporize, Applicants believe that the present sintering technology is far more efficient than conventional processes that use sealed crucibles that surround the sintering material in sand containing the volatile constituent to prevent release of the volatile constituent through high vapor pressures. Applicants have discovered that speed of sintering and geometry of the article may be used to rapidly sinter such volatile materials before too much of the volatile constituent escapes, and a source of excess volatile constituent can be added to green tape, as disclosed above, to greatly improve properties of the resulting sintered article, such as in terms of percentage of cubic crystals, small grain size, less porosity, and greater ionic conductivity, hermeticity, strength, etc.
Still other aspects of the present disclosure relate to a tape (see
According to an exemplary embodiment, geometric consistency of the tape is such that a difference in width of the tape, when measured at locations lengthwise separated by a distance, such as 10 cm, 50 cm, 1 m, 2 m, 10 m is less than a small amount, such as less than 200 μm, less than 100 μm, less than 50 μm, less than 10 μm; and/or a difference in thickness of the tape, when measured at locations lengthwise separated by a distance, such as 10 cm, 50 cm, 1 m, 2 m, 10 m along a widthwise center of the tape (i.e. along the centerline extending the length of the tape), is less than a small amount, such as less than 50 μm, less than 20 μm, less than 10 μm, less than 5 μm, less than 3 μm, less than 1 μm in some such embodiments. Laser trimming may help improve the geometric consistency of the width of the tape. A layer (e.g., silica, a material with melting temperature above 500° C., above 800° C., above 1000° C.), as shown in
In some embodiments, the tape is flat or flattenable, as described above, such that a length of 10 cm of the tape pressed between parallel flat surfaces flattens to contact or to within 0.25 mm of contact with the parallel flat surfaces, such as within 0.10 mm, such as within 0.05 mm, such as within 0.03 mm, such as within 0.01 mm, without fracturing; and for example in some such embodiments, when flattened to within 0.05 mm of contact with the parallel flat surfaces, the tape exhibits a maximum in plane stress of no more than 10% of the Young's modulus thereof, such as no more than 5% of the Young's modulus thereof, such as no more than 2% of the Young's modulus thereof, such as no more than 1% of the Young's modulus thereof, such no more than 0.5% of the Young's modulus thereof. In some embodiments, the first and second major surfaces of the tape have a granular profile, such as where the grains are ceramic (see
In some embodiments, the body has less than 10% porosity by volume and/or the body has closed pores, as shown in
In some embodiments, the tape further includes an electrically-conductive metal coupled to the first major surface of the body, where in some such embodiments the body comprises a repeating pattern of vias, and the electrically-conductive metal is arranged in a repeating pattern (see generally
Additional aspects of the present disclosure relate to a roll of the tape of any one of the above-described embodiments (see, e.g.,
Still other aspects of the present disclosure relate to a plurality of sheets cut from tape of any one of the above-described embodiments (see, generally
Some aspects of the present disclosure relate to a tape, comprising a body comprising ceramic grains sintered to one another, the body extending between first and second major surfaces, where the body has a thickness defined as distance between the first and second major surfaces, a width defined as a first dimension of the first major surface orthogonal to the thickness, and a length defined as a second dimension of the first major surface orthogonal to both the thickness and the width; where the tape is thin, having a thickness in a range from about 3 μm to about 1 mm; and where first and second major surfaces of the tape have a granular profile, and at least some individual grains of the ceramic adjoin one another with little to no intermediate amorphous material such that a thickness of amorphous material between two adjoining grains is less than 5 nm.
Some aspects of the present disclosure relate to a tape or other sintered article (e.g., fiber, tube, sheet, discs), comprising a body comprising ceramic grains sintered to one another, the body extending between first and second major surfaces, where the body has a thickness defined as distance between the first and second major surfaces, a width defined as a first dimension of the first major surface orthogonal to the thickness, and a length defined as a second dimension of the first major surface orthogonal to both the thickness and the width; where the tape is thin, having a thickness in a range from about 3 μm to about 1 mm; where first and second major surfaces of the tape have a granular profile; and where the grains comprise lithium and the body has ionic conductivity greater than 5×10−5 S/cm or higher, as discussed above. Such an article may have a thickness of amorphous material between two adjoining grains is less than 5 nm. In some embodiments, the article is at least 95% dense and has a grain size of less than 10 μm, such as at least 97% dense and has a grain size of less than 5 μm. The article may be co-fired with an anode and/or cathode material as part of a solid state battery, for example.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article “a” is intended to include one or more component or element, and is not intended to be construed as meaning only one. Similarly, pieces of equipment and process steps disclosed herein may be used with materials other than continuous tape. For example, while continuous tape may be particularly efficient for roll-to-roll processing, Applicants have demonstrated that a sled of zirconia or other refractory material may be used to draw discrete sheets of material or other articles through equipment disclosed herein.
It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.
Claims
1. A sheet of material configured for a solid-state battery, comprising:
- a body comprising ceramic grains sintered to one another, wherein the grains comprise lithium, lanthanum, zirconium, and oxygen, and wherein greater than 95% of the body by weight consists of cubic lithium garnet crystals;
- wherein thickness of the body, between first and second major surfaces thereof, is in a range from 3 μm to 100 μm, and wherein the body has a width of 5 mm or greater;
- wherein the body is flattenable without fracturing as determined by pressing the body between rigid parallel surfaces at 23° C. such that the body overlays or is within a distance of 0.05 mm of a flat plane; and
- wherein the grains sintered to one another have an average grain size of 5 μm or less, and wherein the body has ionic conductivity greater than 1×10−4 S/cm.
2. The sheet of claim 1, wherein the body has closed porosity.
3. The sheet of claim 1, wherein the body has less than 10% porosity by volume.
4. The sheet of claim 1, wherein the grains further comprise tantalum, and wherein the body has ionic conductivity greater than 2×10−4 S/cm.
5. The sheet of claim 4, wherein the grains further comprise aluminum.
6. The sheet of claim 1, wherein the body has a length of at least 10 m.
7. A roll of the sheet of claim 6 wound on a spool.
8. A sheet of material configured for a solid-state battery, comprising:
- a body comprising ceramic grains sintered to one another, wherein the grains comprise lithium, and wherein greater than 95% of the body by weight consists of cubic lithium garnet crystals;
- wherein thickness of the body, between first and second major surfaces thereof, is in a range from 3 μm to 50 μm, and wherein the body has a width of 5 mm or greater;
- wherein the body has a length of 1 m or greater;
- wherein fewer than 10 pin holes of a cross-sectional area of at least a square micrometer pass through the body, per square millimeter of surface on average; and
- wherein the grains sintered to one another have an average grain size of 5 μm or less, and wherein the body has ionic conductivity greater than 1×10−4 S/cm.
9. The sheet of claim 8, wherein the body has a length of at least 10 m.
10. A roll of the sheet of claim 9 wound on a spool.
11. The sheet of claim 8, wherein the body has closed porosity.
12. The sheet of claim 11, wherein the body has less than 10% porosity by volume.
13. The sheet of claim 12, wherein the grains further comprise lanthanum, zirconium, and oxygen.
14. A sheet of material configured fora solid-state battery, comprising:
- a body comprising ceramic grains sintered to one another, wherein the grains comprise lithium, lanthanum, zirconium, and oxygen, and wherein greater than 95% of the body by weight consists of cubic lithium garnet crystals;
- wherein thickness of the body, between first and second major surfaces thereof, is in a range from 3 μm to 50 μm, and wherein the body has a width of 5 mm or greater;
- wherein fewer than 10 pin holes of a cross-sectional area of at least a square micrometer pass through the body, per square millimeter of surface on average;
- wherein the body is flattenable without fracturing as determined by pressing the body between rigid parallel surfaces at 23° C. such that the body overlays or is within a distance of 0.05 mm of a flat plane; and
- wherein the grains sintered to one another have an average grain size of 5 μm or less, and wherein the body has ionic conductivity greater than 1×10−4 S/cm.
15. The sheet of claim 14, wherein the body has closed porosity.
16. The sheet of claim 14, wherein the body has less than 10% porosity by volume.
17. The sheet of claim 14, wherein the grains further comprise tantalum, and wherein the body has ionic conductivity greater than 2×10−4 S/cm.
18. The sheet of claim 14, wherein the grains further comprise aluminum.
19. The sheet of claim 14, wherein the body has a length of at least 10 m.
20. A roll of the sheet of claim 19 wound on a spool.
Type: Application
Filed: May 19, 2022
Publication Date: Sep 1, 2022
Inventors: Michael Edward Badding (Campbell, NY), Jacqueline Leslie Brown (Lindley, NY), Jennifer Anella Heine (Belleair Bluffs, FL), Thomas Dale Ketcham (Horseheads, NY), Gary Edward Merz (Rochester, NY), Eric Lee Miller (Corning, NY), Zhen Song (Painted Post, NY), Cameron Wayne Tanner (Horseheads, NY), Conor James Walsh (Campbell, NY)
Application Number: 17/748,242
