Method and device for coating a substrate
Apparatus and methods for coating a substrate. In an exemplary embodiment, the apparatus are used to create a metallized substrate for use as an EMI/RFI shield. The apparatus typically includes a movable processing apparatus that is movable orthogonal to the substrate to treat the substrate. The processing apparatus can include a surface preparation assembly, a heating assembly, a thermoforming assembly, a metallizing assembly, a cutting assembly, or the like.
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The present application claims benefit, under 37 C.F.R. § 1.78, of provisional patent application Ser. No. 60/190,920, filed Mar. 21, 2000 and provisional patent application Ser. No. 60/198,777, filed Apr. 21, 2000, the complete disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTIONThe present invention relates generally to methods and systems for coating a substrate. More particularly, the present invention relates to methods and devices for depositing a metal layer onto a thermoform that is of a sufficient thickness for shielding of electromagnetic interference (“EMI”) and radiofrequency interference (“RFI”).
U.S. Pat. No. 5,811,050 to Gabower, which is incorporated herein by reference, has proposed depositing a thin layer of metal onto a thermoform to create a protective barrier for EMI and RFI. One method for depositing the metal layer onto the thermoform is a batch mode process. A first step of the method includes thermoforming (i.e. shaping) the thermoform substrate. The shaped thermoforms are then placed into the vacuum chamber and a vacuum source is used to create a vacuum in the chamber. A source of metal is vaporized and deposited onto the thermoform substrate.
Unfortunately, the batch processes is slow, time consuming, and impurities can be introduced into the metallized object during transport into and out of the vacuum chamber. For example, one specific problem with the batch process is the creation of the vacuum environment in the deposition chamber. Because the vacuum chamber usually has a large volume (typically about 300,000 in3), the creation of the vacuum environment takes a long period of time to create. Another problem of batch processing is that the thermoform must be separately shaped and cut from the thermoform sheet and it is often necessary to manually handle the thermoformed substrate, both prior and subsequent to the coating process. Care must be taken in such handling steps to avoid contamination or introduction of impurities which may lead to imperfections in the metal layer and leakage in the EMI/RFI shield.
Therefore, what is needed are vapor deposition processes and apparatuses for coating objects with a coating material that have improved process speed and improved process control characteristics.
DESCRIPTION OF BACKGROUND ARTU.S. Pat. No. 5,908,506 provides a continuous vapor deposition apparatus that appears to have stationary process chambers. U.S. Pat. No. 5,811,050 describes an apparatus for vacuum depositing a metallic coating on thermoformed blanks that are placed on a carrier that revolves around a stationary tungsten filament. U.S. Pat. No. 5,076,203 recites passing a web over spools past a stationary source of metal and an electron beam heater. U.S. Pat. No. 4,261,808 describes a vertical vacuum coating apparatus that deposits a metal layer onto a moving substrate with a fixed cathode system.
SUMMARY OF THE INVENTIONThe present invention provides improved methods and systems for depositing a coating material onto a substrate. In exemplary embodiments, the methods and systems are used for vacuum metallizing a thermoform or other substrate for creating an EMI RFI shield.
The systems of the present invention generally have at least one processing apparatus that is movable orthogonal to a plane of the substrate. The processing apparatus can be moved adjacent the substrate or to contact the substrate, a platform, and/or a second processing apparatus to process the substrate. In some embodiments, the processing apparatuses have a small volume cavity in which a vacuum can be created for the delivery of a vaporized metal or other coating material. The small vacuum cavities of the processing apparatuses of the present invention allow a vacuum source to create a vacuum environment in a shorter amount of time than conventional vacuum chambers, thus improving the speed of manufacturing of the substrates. The cavities of the processing apparatuses can house a shaping assembly, a pre-treatment assembly (e.g. glow discharge), a metallizing assembly (e.g. vacuum metallization, arc plasma deposition, ion deposition), heating elements, a cutting assembly or the like.
In some configurations, the systems of the present invention are configured as in-line system that has a plurality of movable processing apparatuses. Advantageously, the in-line systems of the present invention allow for the processing of spools or rolls of a substrate, such as a thermoform, such that no manual handling of the thermoform is required in intermediate steps. The processing apparatuses can be configured to thermoform, pre-treat the substrate, metallize and/or cut the thermoform using the single in-line system.
The substrate may enter into the processing area either as a structural form which has been subject to prior processing (referred to as thermoforming) or the substrate may enter the processing area as a flat substrate and be subject to thermoforming followed by metallization, or alternatively vacuum metallization followed by thermoforming. For example, in some exemplary embodiments, the systems of the present invention include a series of movable processing apparatuses on one or both sides of the substrate. The assemblies can all be adapted to perform the same function (e.g. metallize) or each of the processing apparatuses can perform different functions (e.g., thermoform, metallize and cut). For example, for one exemplary in-line system, the substrate can be moved to a first processing apparatus for shaping (e.g., thermoforming) of the substrate. The shaped substrate can be then be moved to a second processing apparatus which can deposit a metal layer onto the shaped substrate (e.g., vacuum metallization). Finally, the shaped and metallized substrate can be transported to a third processing apparatus that can cut the shaped and metallized form out of the substrate. It should be appreciated that additional processing apparatuses can also be incorporated into the previous example, such as surface treatment apparatuses, heating apparatuses, or the like.
In some exemplary configurations, the processing apparatuses of the present invention can include one or more modular units for providing multiple interfaces for processing the substrate. Such processing apparatuses will be movable orthogonal to the plane of the substrate and rotatable so that a desired processing interface of the modular units can be moved into position to process the substrate. Such a configuration allows for a multitude of processes to be accomplished either on a single sheet of material or as a part of a continuous inline process in which a polymer or flexible film is unrolled and processed from beginning to end.
Typically, each processing apparatus includes at least three modular units, and preferably between three and six modular units. Each modular unit of each processing apparatus can have the same or different functions. For example, in some processing apparatuses each of the modular units will have the same modular unit, for example a metallization unit. The metallization unit will be used deposit a metal layer onto the substrate. Once the metal source has been depleted in the metallization unit, the processing apparatus can be rotated and a metallization unit having a full metal source can be used. Once the depleted metal source has been rotated away, the metal source can be manually or mechanically replaced. Such a configuration limits the “down time” of the system and improves the output and production of the system.
Alternatively, each of the modular units of the processing apparatus can have a different functional modular unit. For example, a first modular unit can be used to heat the thermoform. The first modular unit can be rotated away and a second shaping modular unit can process and shape the substrate. Thereafter, the next modular units, such as a surface treatment assembly, metallization assembly, and cutting assembly modular unit can be rotated towards the substrate to process the substrate. Advantageously, if desired the rotatable, modular processing apparatuses allow for multiple or complete processing of the substrate while maintaining the position of a substrate in a single position. Such systems can reduce the footprint of the system on the manufacturing floor.
In exemplary embodiments, the present invention can create EMI/RFI shields that can be used within electronic devices and products to reduce the amount of electromagnetic radiation that is emitted from and enters the electronic device. In an exemplary embodiment, the EMI/RFI shields enabled by the equipment described above are based upon the application of a relatively stable and uniform layer of aluminum on a polymer substrate. The present invention can apply any number of different metal layers (e.g., silver, copper, gold, nickel, or the like) to any number of substrate materials (e.g., polycarbonate, ABS, PVC, or the like) through a variety of metallization processes.
In one aspect, the present invention provides an apparatus for coating a substrate. The apparatus comprises a support that supports the substrate and at least one movable processing apparatus that can deposit a metal layer onto the substrate. The processing apparatus is movable between a first position adjacent the substrate and a second position apart from the substrate.
In another aspect, the present invention provides an apparatus for metallizing a substrate. The apparatus comprises a support that can maintain at least a portion of the substrate along a first plane and at least one rotatable processing apparatus that is movable substantially orthogonal to the orientation of the substrate. The processing apparatus comprises a plurality of modular units that includes at least one of a thermoform assembly, a heating assembly, a metallizing assembly, or a cutting assembly.
In another aspect, the present invention provides an in-line apparatus for creating an EMI shield, the apparatus comprises a conveyor assembly that moves a substrate from a first position to a second position and a movable shaping chamber disposed at the first position to shape the substrate. A metallization chamber can create a seal around the shaped substrate and can deposit a metal layer onto the shaped substrate, and a cutting assembly disposed at the second position to cut the shaped substrate, the cutting assembly being movable relative to the shaped substrate.
In yet another aspect, the present invention provides a method of manufacturing an EMI shield. The method comprises positioning a substrate on a support. A processing apparatus is moved adjacent to the substrate, a metal layer is deposited on the substrate and the processing apparatus is moved away from the substrate.
For a further understanding of the nature and advantages of the invention, reference should be made to the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention provides improved systems and methods for depositing a metal layer onto a shaped polymer substrate. In exemplary embodiment, the systems of the present invention rely on the use of at least one movable processing apparatus to treat a substrate. Treatments can include surface treatment, preheating, shaping, depositing a metal layer, cutting, or the like.
In a specific use, the methods and systems of the present invention are for use in producing EMI/RFI shields for electronic devices. In particular, the final EMI/RFI shields are composed of a metallized thermoform that are manufactured with the processes and systems of the present invention. In most embodiments, the systems of the present invention include at least one movable processing apparatus, and typically a first processing apparatus disposed on a first side of the substrate and a second processing apparatus disposed on a second side of the substrate. Such a configuration helps in the efficient treatment of both sides of the substrate. For example, in the embodiments in which the processing apparatus shapes the substrate, the first processing apparatus can include a mold while the second side can include a corresponding mold to shape the substrate. Moreover, if the processing apparatus is used to deposit a metal layer onto the substrate, both the first and second processing apparatus can be used so as to metallize both sides of the substrate.
While the remaining discussion will focus on an in-line process for thermoforming, metallizing, and cutting a polymer substrate to create an EMI/RFI shield, it should be appreciated that the apparatuses of the present invention can be adapted to perform only a single process of the processing of the substrate. For example, the apparatuses of the present invention can be used to only metallize flat substrates. Alternatively, the apparatuses of the present invention can be used to only shape (e.g., thermoform) the substrate. Additionally, the apparatus does not have to be an in-line process, but instead the processing apparatus can be a stand alone device that allows a user to manually position the substrate in a processing position. Finally, it should also be appreciated that the methods and systems of the present invention can also extend to depositing a coating on any type of substrate.
Referring now to
As illustrated in
As shown in
Exemplary rotatable processing apparatuses of the present invention are illustrated in
As illustrated in
Each of the first and second processing apparatuses 16, 16′ can include a plurality of nominally independent modular units 50.
As illustrated in
Two specific arrangements of the canes 80 and filaments 78 are illustrated in
As shown in
Each of the modular units 50 will include a number of conduits and ports for coupling the assemblies 64, 72, 76, 90 to their respective sources (e.g. power source, gas source, vacuum source, or the like).
An exemplary method of the present invention will now be described in relation to the manufacturing of an EMI/RFI shield that is composed of a metallized polymer substrate. In particular, the following method will be in relation to an in-line process of metallizing a thermoform. The thermoform can be automatically or manually roll-fed or sheet-fed into the processing apparatuses of the present invention. A first station is typically a shaping or thermoforming station. Thermoforming is the heating and molding of plastic substrate into a shaped product. The shaped product can take a variety of forms to create an EMI shield. Various EMI shields are described and illustrated in U.S. Pat. No. 5,811,050 and patent application Ser. No. 09/788,263, filed Feb. 16, 2001, entitled “EMI and RFI Shielding for Printed Circuit Boards” (Attorney Docket No. 020843-000200US) and Ser. No. 09/785,975 filed Feb. 16, 2001, entitled “Electromagnetic Interference Shielding of Electrical Cables and Connectors” (Attorney Docket No. 020843-000100US), and PCT Application No. 00/27610, filed Oct. 6, 2000, entitled “EMI Containment Apparatus” (Attorney Docket No. 020843-000300PC), the complete disclosures of which are incorporated herein by reference.
The shaping processing apparatus 26 (for example
The shaped substrate can then be transported either manually or with a conveyor system 32 to the metallization assembly 28. The metallization assembly 28 can create a vacuum around the desired portion of the substrate and the metal layer can be deposited onto the shaped substrate. Thereafter, the metallized substrate can be moved to the cutting assembly 30 for final processing of the substrate (
While all the above is a complete description of the preferred embodiments of the inventions, various alternatives, modifications, and equivalents may be used. For example, while the systems of the present invention are illustrated with the processing unit and substrate in a horizontal position, it should be appreciated that the substrate can be moved in a vertical direction, if desired As will be appreciated by those of ordinary skill in the art, the foregoing description is intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.
Claims
1.-31. (canceled)
32. A method of manufacturing a EMI shield, the method comprising:
- positioning a substrate on a support;
- moving a processing apparatus adjacent to the substrate;
- depositing a metal layer on the substrate; and
- moving the processing apparatus away from the substrate.
33. The method of claim 32 further comprising creating a vacuum around at least a portion of the substrate.
34. The method of claim 32 further comprising moving the substrate along the support.
35. The method of claim 32 further comprising shaping the substrate before depositing the metal layer.
36. The method of claim 35 wherein depositing requires rotating a processing apparatus to rotate a shaping module away from the substrate and a metal depositing module toward the substrate.
37. The method of claim 35 comprising cutting the shaped substrate after depositing the metal layer.
Type: Application
Filed: Dec 13, 2004
Publication Date: Sep 15, 2005
Applicants: Wavezero, Inc. (Sunnyvale, CA), Shielding for Electronics, Inc. (Sunnyvale, CA)
Inventor: Rocky Arnold (San Carlos, CA)
Application Number: 11/010,559