METHODS AND SYSTEMS FOR INCREASING SURFACE AREA OF MULTILAYER CERAMIC CAPACITORS
Methods and systems to improve a multilayer ceramic capacitor using additive manufacturing are disclosed. Layers of a capacitor may be modified from its traditional planar shape to a wavy structure. The wavy shape increases surface area within a fixed volume of the capacitor, thus increasing capacitance, and may comprise smooth and repetitive oscillations without the presence of voltage-degrading sharp corners. In addition, the ends of each conductive layer do not have sharp edges, such as comprising a round corner. The one-dimensional wave pattern may run parallel to the width of the capacitor, or it may align in parallel to the length of the capacitor. In some embodiments, the wave pattern may be parallel to both the width and the length—in two dimensions—such that it forms an egg-crate shape. Further, the wavy structures may comprise of secondary or tertiary wavy structures to further increase surface area.
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This patent application is a continuation-in-part and claims priority from:
- (1) U.S. provisional patent application number 62/194,256, titled ‘Methods and systems for increasing capacitance of multi-layer ceramic capacitors’, filed on Jul. 19, 2015.
- (2) U.S. provisional patent application number 62/211,792, titled ‘Methods and systems for geometric optimization of multi-layer ceramic capacitors’, filed Aug. 30, 2015.
- (3) U.S. provisional patent application number 62/232,419, titled ‘Methods and systems for material cladding of multi-layer ceramic capacitors’, filed Sep. 24, 2015.
- (4) U.S. provisional patent application number 62/266,618, titled ‘Methods and systems to improve printed electrical components and for integration in circuits“, filed Dec. 13, 2015.
- (5) U.S. provisional patent application number 62/279,649, ‘Methods and systems to minimize delamination of multi-layer ceramic capacitors”, filed Jan. 15, 2016.
This disclosure relates generally to forming a novel structure of multilayer ceramic capacitors (MLCC) using the technique of drop-on-demand additive printing to deposit droplets of deposition material.
BACKGROUNDDensity is a much-sought advantage in electronic components. If specifications can be maintained while reducing the size of a component, devices made from those components can be made using less material (reducing cost and weight) while also reducing bulk. Or, a component can be given enhanced specifications with the same amount of material, if that leads to superior devices. While transistor density has increased dramatically for decades, improvements in “passive” components such as capacitors have not kept pace.
Multilayer ceramic capacitors, or MLCCs, have traditionally been made by forming a tape from insulating ceramic slurry, printing conductive ink layers, and then pressing the layers together and sintering to form a laminated alternation of insulator and conductor. Particularly in the case of a physically large capacitor, there is a possibility of delamination under the stress of temperature or pressure. If a layer separates, even slightly, there is a drop in the capacitance that can render it out of specification, or there can be complete device failure. In addition, the process may be limited to simple flat layers and complex shapes may not be possible.
The goal, therefore, is to find a way to increase both the capacitance and the maximum voltage for a given form factor. As such, there is a need for a technique that is better equipped to optimize geometrical features to increase specifications of an MLCC.
SUMMARYDisclosed are methods, apparatus, and systems to geometrically optimize multilayer ceramic capacitors (MLCCs). As disclosed herein, the total surface area of the conductors may be increased within a fixed volume.
In one aspect, the present invention discloses a system and a method to improve a ceramic capacitor using additive manufacturing, e.g., 3D Printing, where ink or aerosol jets deposit material such as, e.g., ceramic slurry, conductive ink, ferrite paste, and carbon resistor paste onto a surface. The aforementioned materials can be sintered at high temperatures, and therefore are amenable to integrated manufacture. Compared with traditional methods, this process may be inherently more precise and repeatable, has much higher geometric and spatial resolutions, and produces higher density components with less material waste. In addition, a key advantage for purposes of this invention is that more complex shapes that were not possible before can now be printed, which can be used to improve specification and/or structural integrity of the product.
A typical implementation of an additive manufacturing process begins with defining a three-dimensional geometry of the product using computer-aided design (CAD) software. This CAD data is then processed with software that slices the model into a plurality of thin layers, which are essentially two-dimensional. A physical part is then created by the successive printing of these layers to recreate the desired geometry. This process is repeated until all the layers have been printed. Typically, the resulting part is a “green” part, which may be an unfinished product that can undergo further processing, e.g., sintering. The green part may be dense and substantially non-porous.
Layers of a multilayer ceramic capacitor may be modified from its traditional planar shape to a wave-like structure that is produced by a system or a method of the present invention. The wave shape increases surface area within a fixed volume of the capacitor, thus increasing capacitance, and may comprise smooth and repetitive oscillations without the presence of voltage-degrading sharp corners. In addition, the ends of each conductive layer do not have sharp edges, such as comprising of a round corner. The one-dimensional wave pattern may run parallel to the width of the capacitor, or it may align in parallel to the length of the capacitor. In some aspects, the wave pattern may be parallel to both the width and the length—in two dimensions—such that it forms an egg-crate shape. Further, the wave-like structures may comprise of secondary or tertiary wave-like structures to further increase surface area.
Example embodiments are illustrated by way of example and are not limited to the figures of the accompanying drawings, in which, like references indicate similar elements.
Disclosed are methods, apparatus, and systems to geometrically optimize MLCC. Although the present embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. In addition, the components shown in the figures, their connections, couples, and relationships, and their functions, are meant to be exemplary only, and are not meant to limit the embodiments described herein.
A capacitor is an electrical device that stores energy in the electric field between a pair of closely spaced conductors. Capacitors may be used as energy-storage devices, and may also be used to differentiate between high-frequency and low-frequency signals. Capacitance value may be defined as a measure of how much charge a capacitor can store at a certain voltage.
where K is the ratio of the insulator permittivity to that of a vacuum (sometimes called the dielectric constant of the material), and €o is the permittivity of a vacuum. The formula may be inexact due to edge effects: at the border of the parallel plates, the electric field bulges away from the capacitor. If the plate size is large relative to separation ‘d’, the edge effect is negligible.
Since a use of capacitors is to store energy, anything that can increase the maximum voltage may be desirable since the energy may increase as the square of the voltage; however, exceeding the maximum voltage may cause a miniature lightning strike through the insulator that can render the capacitor inoperable.
A multilayer ceramic capacitor (MLCC) may be a device made of ceramic and metal that alternate to make a multilayer chip. The capacitance value of an MLCC may be determined by several factors, such as geometry of the part, e.g., shape and size, and total active area. The dielectric constant, K, may be determined by the ceramic material. The total active area may be the overlap between two opposing electrodes. A thickness of the dielectric ceramic material may be inversely proportional to the capacitance value such that the thicker the dielectric, the lower the capacitance value. This may also determine the voltage rating, with a thicker dielectric layer comprises a higher voltage rating that a thinner one.
A plurality of conductive layer 302 may be alternately connected to termination A 306 and termination B 308, such that termination A 306 is connected to every second conductive layer 302, and termination B 308 is connected with the remaining conductive layer 302 not connected to termination A 306. Conductive layer 302 and dielectric layer 304 may have flat surfaces, and the thickness of conductive layer 302 may be spatially uniform, e.g., same height. When a voltage is applied to termination A 306 and termination B 308, the MLCC may produce electric fields between every two neighboring conductive layer 302 and store electric charges therein.
Multilayer ceramic capacitors have traditionally been made by forming a tape from insulating ceramic slurry, printing conductive ink layers, pressing the layers together, and then sintering to form a laminated alternation of insulator and conductor. However, particularly in the case of a physically large MLCC, there is a possibility of delamination under the stress of temperature or pressure. If a layer separates, even slightly, there is a drop in the capacitance that can render it out of specification, or there can be complete device failure. In addition, the process may be limited to simple flat layers and complex shapes may not be possible, such as to avoid sharp corners that can cause voltage breakdown.
In at least one embodiment, the present invention discloses a system and a method to improve a ceramic capacitor using additive manufacturing, e.g., 3D Printing, where ink or aerosol jets deposit material such as, e.g., ceramic slurry, conductive ink, ferrite paste, and carbon resistor paste onto a surface. The aforementioned materials can be sintered at high temperatures, and therefore are amenable to integrated manufacture. Compared with traditional methods, this process may be inherently more precise and repeatable, has much higher geometric and spatial resolutions, and produces higher density components with less material waste. In addition, a key advantage for purposes of this invention is that more complex shapes that were not possible before can now be printed, which can be used to improve specification and/or structural integrity of the product.
A typical implementation of an additive manufacturing process begins with defining a three-dimensional geometry of the product using computer-aided design (CAD) software. This CAD data is then processed with software that slices the model into a plurality of thin layers, which are essentially two-dimensional. A physical part is then created by the successive printing of these layers to recreate the desired geometry. This process is repeated until all the layers have been printed. Typically, the resulting part is a “green” part, which may be an unfinished product that can undergo further processing, e.g., sintering. The green part may be dense and substantially non-porous.
A plurality of conductive layer 702 may be alternately connected to termination A 706 and termination B 708, such that termination A 706 is connected to every second conductive layer 702, and termination B 708 is connected with the remaining conductive layer 702 not connected to termination A 706. When a voltage is applied to termination A 706 and termination B 708, the MLCC may produce electric fields between every two neighboring conductive layer 302 and store electric charges therein.
Conductive layer 702 may be modified from its traditional planar shape to a wave-like structure that is produced by a system or a method of the present invention. The wave shape increases surface area within a fixed volume of the capacitor, thus increasing capacitance, and may comprise smooth and repetitive oscillations without the presence of voltage-degrading sharp corners. In addition, the ends of each conductive layer 702 do not have sharp edges, such as comprising of a round corner. The one-dimensional wave pattern may run parallel to the width of the capacitor as in
In some embodiments, the wavy shape of conductive layer 702 may be oriented in a diagonal direction, such as emanating from one corner of the body 700 flowing towards its opposite corner. The wave shape in the diagonal direction may traverse the width or the length of the body 700, and made possible by the method and system of the present invention.
However, the separation of the two conductors in the direction normal to the conductors may be less than or equal to the ‘d’ value for parallel flat plates. The insulator may be pinched to about 0.7 d—or (2√/2)d—at the points of maximum upward and downward slope. This may further increase the capacitance value C, since capacitance grow inversely with separation distance.
In some embodiments, the wavy shape of conductive layer 1000 may be oriented in diagonal directions, such as emanating from one corner of the capacitor flowing towards its opposite corner. The wave shape in the diagonal directions may traverse the width and the length of the capacitor, such that the undulations are angled (1 degree to 90 degrees), and made possible by the method and system of the present invention.
A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the claimed invention. In addition, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other embodiments are within the scope of the following claims. It may be appreciated that the various systems, methods, and apparatus disclosed herein may be embodied in a machine-readable medium and/or a machine accessible medium, and/or may be performed in any order. The structures and modules in the figures may be shown as distinct and communicating with only a few specific structures and not others. The structures may be merged with each other, may perform overlapping functions, and may communicate with other structures not shown to be connected in the figures. Accordingly, the specification and/or drawings may be regarded in an illustrative rather than a restrictive sense.
Claims
1. A method, comprising:
- defining a three-dimensional geometry of a multilayer ceramic capacitor;
- depositing at least one layer of slurry comprising powder material and binder on top of a powder bed,
- wherein the layer comprises an insulator material or a conductor material;
- drying the powder bed after deposition of each layer; and
- sintering the one or more layers to form the multilayer ceramic capacitor.
2. The method of claim 1, further comprising:
- wherein the ceramic capacitor comprises a ceramic body;
- one or more dielectric layers alternately stacked with two or more conductive layers,
- wherein at least one conductive layer is configured to be structurally sinusoidal,
- wherein the structurally sinusoidal conductive layers are aligned in a same vertical phase when two or more conductive layers are structurally sinusoidal;
- a pair of external termination disposed at opposite end portions of the body, and
- wherein the two or more conductive layers are alternately coupled to an external termination of the pair of external termination.
3. The method of claim 2, further comprising:
- wherein each structurally sinusoidal conductive layer does not comprise a sharp corner.
4. The method of claim 2, further comprising:
- wherein a non-coupled end of a structurally sinusoidal conductive layer comprises an end that points upward, or
- wherein a non-coupled end of a structurally sinusoidal conductive layer comprises an end that points downward.
5. The method of claim 2, further comprising:
- wherein the sinusoidal structure of the conductive layer runs parallel to a width of the multilayer ceramic capacitor.
6. The method of claim 2, further comprising:
- wherein the sinusoidal structure of the conductive layer runs parallel to a length of the multilayer ceramic capacitor.
7. A method, comprising:
- depositing a slurry to form a first layer comprising conductive material;
- wherein the conductive material comprises at least one of a copper, nickel, silver, palladium, gold and platinum;
- depositing a slurry to form a second layer comprising dielectric material,
- wherein the dielectric material comprises barium titanate;
- depositing a slurry to form a third layer comprising the same material as the first layer;
- drying the layers using infrared heating; and
- sintering the layers to form a multilayer ceramic capacitor.
8. The method of claim 7, further comprising:
- wherein the ceramic capacitor comprises a ceramic body;
- wherein one or more dielectric layers are alternately stacked with two or more conductive layers,
- wherein at least one conductive layer comprises an egg-crate shape;
- a pair of external termination disposed at two opposite end portions of the body,
- wherein the two or more conductive layers are alternately coupled to an external termination of the pair of external termination, and
- wherein an electric field is generated between two juxtapose conductive layers when voltage is applied to the pair of external termination.
9. The method of claim 8, further comprising:
- wherein undulations of the egg-crate shape conductive layers vertically align when there are two or more egg-crate shape conductive layers.
10. The method of claim 8, further comprising:
- wherein the undulations of the egg-crate shape conductive layer comprise secondary undulations.
11. The method of claim 10, further comprising:
- wherein the secondary undulations of the egg-crate shape conductive layer comprise tertiary undulations.
12. The method of claim 10, further comprising:
- wherein the secondary undulations of the egg-crate shape conductive layer vertically align when there are two or more egg-crate shape conductive layers comprising secondary undulations, or
- wherein the secondary undulations of the egg-crate shape conductive layer do not vertically align when there are two or more egg-crate shape conductive layers comprising secondary undulations.
13. The method of claim 10, further comprising:
- wherein the secondary undulations of the egg-crate shape conductive layer are evenly spaced and sized, or
- wherein the secondary undulations of the egg-crate shape conductive layer are not evenly spaced and sized.
14. The method of claim 10, further comprising:
- wherein the secondary undulations of the egg-crate shape conductive layer is disposed on only a portion of the conductive layer.
15. A method, comprising:
- depositing a first conductive layer onto a surface;
- depositing a dielectric layer on a top surface of the first conductive layer;
- depositing a second conductive layer a top surface of the dielectric layer;
- repeating each step until green part is formed; and
- sintering the green part to form a multilayer ceramic capacitor.
16. The method of claim 15, further comprising:
- wherein the ceramic capacitor comprises a ceramic body;
- one or more dielectric layers alternately stacked with two or more conductive layers,
- wherein at least one conductive layer comprises a wavy shape, and
- wherein the wavy shape conductive layers are aligned in a same vertical phase when two or more conductive layers comprise a wavy shape.
17. The method of claim 16, further comprising:
- wherein the thicknesses of the conductive layers and the dielectric layers are spatially uniform throughout each layer, or
- wherein the thicknesses of the conductive layer and the dielectric layer are spatially varying throughout each layer.
18. The method of claim 16, further comprising:
- wherein the thicknesses of the conductive layers and the dielectric layers are spatially uniform among respective layers of the multilayer ceramic capacitor, or
- wherein the thicknesses of the conductive layers and the dielectric layers are spatially varying among respective layers of the multilayer ceramic capacitor.
19. The method of claim 16, further comprising:
- wherein a plurality of crests of the wavy shape conductive layer comprises a uniform height, or
- wherein a plurality of crests of the wavy shape conductive layer comprises varying heights.
20. The method of claim 16, further comprising:
- wherein a thickness of the dielectric layer is constant throughout the layer.
Type: Application
Filed: Nov 2, 2018
Publication Date: Mar 14, 2019
Applicant:
Inventor: John L. Gustafson (Santa Clara, CA)
Application Number: 16/178,594