Thermoformable polymer thick film transparent conductor and its use in capacitive switch circuits
AssigneeE. I. Du Pont de Nemours and Company
InventorJay Robert Dorfman
Life of this patent
Estimating the term…
Abstract
This invention is directed to a polymer thick film transparent conductor composition that may be used in applications where thermoforming of the base substrate occurs, e.g., as in capacitive switches. Polycarbonate substrates are often used as the substrate and the polymer thick film conductive composition may be used without any barrier layer. Depending on the specific design, the thermoformable transparent conductor may be below or on top of a thermoformable silver conductor. Thermoformable electric circuits benefit from the presence of an encapsulant layer over the dried polymer thick film transparent conductor composition. The electrical circuit may be subsequently subjected to an injection molding process.
Claims27
A polymer thick film transparent conductor composition comprising:
- (a) 10-70 wt % of a conductive oxide powder selected from the group consisting of indium tin oxide powder, antimony tin oxide powder and mixtures thereof;
- and
- (b) 30-90 wt % of an organic medium comprising 1-50 wt % thermoplastic urethane resin and 10-50 wt % thermoplastic polyhydroxyether resin, wherein the thermoplastic urethane resin and the thermoplastic polyhydroxyether resin are both dissolved in triethyl phosphate and wherein the weight percent of the thermoplastic urethane resin and the thermoplastic polyhydroxyether resin are based on the total weight of the organic medium;
- wherein the weight percent of the conductive oxide powder and the organic medium are based on the total weight of the polymer thick film transparent conductor composition.
A capacitive switch circuit comprising a substrate and a transparent conductor formed from a polymer thick film transparent conductor composition comprising:
- (a) 10-70 wt % of a conductive oxide powder selected from the group consisting of indium tin oxide powder, antimony tin oxide powder and mixtures thereof;
- and
- (b) 30-90 wt % of an organic medium comprising 1-50 wt % thermoplastic urethane resin and 10-50 wt % thermoplastic polyhydroxyether resin, wherein the thermoplastic urethane resin and the thermoplastic polyhydroxyether resin are both dissolved in triethyl phosphate and wherein the weight percent of the thermoplastic urethane resin and the thermoplastic polyhydroxyether resin are based on the total weight of the organic medium;
- wherein the weight percent of the conductive oxide powder and the organic medium are based on the total weight of the polymer thick film transparent conductor composition.
A capacitive switch circuit comprising a substrate, a dried encapsulant layer and a transparent conductor formed from a dried polymer thick film transparent conductor composition, said polymer thick film transparent conductor composition comprising:
- (a) 10-70 wt % of a conductive oxide powder selected from the group consisting of indium tin oxide powder, antimony tin oxide powder and mixtures thereof;
- and
- (b) 30-90 wt % of an organic medium comprising 1-50 wt % thermoplastic urethane resin and 10-50 wt % thermoplastic polyhydroxyether resin, wherein the thermoplastic urethane resin and the thermoplastic polyhydroxyether resin are both dissolved in triethyl phosphate and wherein the weight percent of the thermoplastic urethane resin and the thermoplastic polyhydroxyether resin are based on the total weight of the organic medium;
- wherein the weight percent of the conductive oxide powder and the organic medium are based on the total weight of the polymer thick film transparent conductor composition.
An electrical circuit comprising a substrate, a dried encapsulant layer and a transparent conductor formed from a dried polymer thick film conductive composition, said polymer thick film conductive composition comprising:
- (a) 10-70 wt % 10-70 wt % of a conductive oxide powder selected from the group consisting of indium tin oxide powder, antimony tin oxide powder and mixtures thereof;
- (b) 10-50 wt % first organic medium comprising 10-50 wt % thermoplastic urethane resin dissolved in a first organic solvent, wherein the weight percent of the thermoplastic urethane resin is based on the total weight of the first organic medium;
- and
- (c) 10-50 wt % second organic medium comprising 10-50 wt % thermoplastic polyhydroxyether resin dissolved in an organic solvent wherein the weight percent of the thermoplastic polyhydroxyether resin is based on the total weight of the second organic medium;
- wherein the weight percent of said conductive oxide powder, said first organic medium and said second organic medium are based on the total weight of said polymer thick film transparent conductor composition, wherein said polymer thick film transparent conductor composition is dried to form said transparent conductor before said encapsulant layer, comprising the same resins in the same ratios or in different ratios as present in said polymer thick film transparent conductor composition, is deposited and dried, and wherein said electrical circuit is thermoformed.
Dependencies are inferred from the claim text.