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Method for preventing or reducing silver migration in the crossover areas of a membrane touch switch

A technology of buttons and switches, applied in the direction of electric switches, conductive materials dispersed in non-conductive inorganic materials, superimposed layer plating, etc.

Inactive Publication Date: 2012-07-18
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These methods have not been used to adequately address silver migration in many applications

Method used

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  • Method for preventing or reducing silver migration in the crossover areas of a membrane touch switch
  • Method for preventing or reducing silver migration in the crossover areas of a membrane touch switch
  • Method for preventing or reducing silver migration in the crossover areas of a membrane touch switch

Examples

Experimental program
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no. 3 approach

[0044] The third embodiment is as follows:

[0045] A method of forming a membrane key switch, comprising:

[0046] (a) coating a substrate with a bottom silver composition;

[0047] (b) drying or curing silver composition

[0048] (c) Applying a carbon coating on top of the silver composition

[0049] (d) drying or curing the carbon composition

[0050] (e) applying a dielectric composition on top of said carbon

[0051] (f) drying or curing the dielectric composition

[0052] (g) placing a top layer of silver on the dielectric

[0053] (h) drying the silver paste composition to form a circuit.

no. 4 approach

[0054] The fourth embodiment is as follows:

[0055] A method of forming a membrane key switch, comprising:

[0056] (a) coating a substrate with a bottom silver composition;

[0057] (b) drying or curing silver composition

[0058] (c) applying a dielectric composition on top of said silver

[0059] (d) drying or curing the dielectric composition

[0060] (e) Applying a carbon coating on top of the dielectric composition

[0061] (f) dry or solidified carbon composition

[0062] (g) placing a top layer of silver on the carbon

[0063] (h) drying the silver paste composition to form a circuit.

[0064] Switches produced by such methods are also contemplated.

[0065] In the above embodiments, substrates that can be used include, but are not limited to: DuPont ST505, ST504 polyester film, DuPont Kapton polyimide film, polycarbonate film, FR-4 circuit board. Those skilled in the art will know of other substrates that can be used in the present invention.

[0066] In the a...

Embodiment 1

[0072] Step 1: A solvent based or UV curable silver containing conductor composition or paste such as DuPont 5025 will be applied to polyester, polyimide, polycarbonate or other flexible or rigid substrates such as DuPont-Tejin Films ST5055mil polyester film to form bottom circuit lines or traces. These circuit lines are typically 5–500mil in width. The silver-containing composition is then dried in a belt or box oven at a temperature between 100C-250C for 0.5-45 minutes, or cured in a UV curing unit at the desired wavelength for the required time to form bottom circuit layer.

[0073] Step 2: A solvent based or UV cured carbon based conductor composition or paste such as DuPont 7102 will be screen printed or otherwise patterned using stainless steel or polyester screens of various mesh counts and wire or wire diameters A forming method such as inkjet or flexographic printing is applied to the overlapping areas of the silver circuit described above to form an overprint on th...

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Abstract

Disclosed is the use of carbon layers as barriers to prevent silver migration in circuitry crossovers, either over a bottom circuitry layer and / or beneath subsequent circuit layers.

Description

field of invention [0001] The present invention relates to preventing or reducing silver migration at circuit overlap regions of membrane key switches by encapsulating the silver with a carbon layer to reduce or prevent silver migration. Background of the invention [0002] In the overlapping area of ​​the membrane key switch, the silver conductors of opposite polarity are usually separated by a dielectric insulation layer. Silver migration may occur at circuit overlap areas over time and exposure to high temperature and humidity. Previously, only dielectric insulating layers have been used as insulators between circuit layers of opposite polarity and have been the only method used to prevent silver migration between these circuit layers. These methods have not been used to adequately address silver migration in many applications. Summary of the invention [0003] The present invention relates to a method of forming a membrane key switch comprising: (a) coating a substra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C28/00H01B1/22H05K1/09H01H13/704
CPCH05K3/4685C23C28/00H05K2201/0769C23C28/322H05K3/245C23C28/34H05K2201/0323H05K3/249H05K1/095
Inventor J·C·克伦普顿R·P·沃尔德罗普
Owner EI DU PONT DE NEMOURS & CO