Thick film conductor compositions for use in membrane switch applications
View Patent ↗The present invention relates to a thick film conductor composition comprising: (a) electrically conductive silver powder; (b) PVDF/HFP polymer resin, copolymers of a PVDF/HFP polymer resin, and mixtures thereof; dissolved in (c) organic solvent, with the provisos that the PVDF/HFP resin has a melt viscosity of 0.2–0.7 kPoise and a DSC melt temperature in the range of 85–98° C.
1. A thick film conductor composition comprising:
a) electrically conductive silver powder;
b) PVDF/HFP polymer resin, copolymers of a PVDF/HFP polymer resin, and mixtures thereof; dissolved in
c) organic solvent;
with the provisos that the PVDF/HFP resin has a melt viscosity of 0.2–0.7 kPoise and a DSC melt temperature in the range of 85–98° C.
2. The composition of claim 1 wherein the PVDF/HFP resin contains about 12–16 mole % of hexafluoropropylene (HFP) in the total resin composition.
3. The composition of claim 1 wherein the boiling point of the organic solvent is in the range of 180° C. to 250° C.
4. The composition of claim 1 wherein the organic solvent is selected from the group comprising glycol ethers, ketones, esters, and mixtures thereof.
5. A method of forming a membrane touch switch comprising:
a) preparing the composition of claim 1 ;
b) applying the composition of a) onto a substrate;
c) drying the composition of b) to form a circuit; and
d) applying a voltage across the circuit of c).
6. A membrane touch switch utilizing the composition of claim 1 .
7. A membrane touch switch formed by the method of claim 5 .