High K dielectric composition for thermoformable capacitive circuits

1. A polymer thick film thermoformable dielectric composition consisting of:

(a) 15-50 wt % of a first organic medium consisting of 10-50 wt % urethane resin dissolved in 50-90 wt % first organic solvent, wherein the weight percent of the urethane resin and the first organic solvent are based on the total weight of the first organic medium; and

(b) 15-50 wt % of a second organic medium consisting of 10-50 wt % thermoplastic phenoxy resin in 50-90 wt % second organic solvent wherein the weight percent of the thermoplastic phenoxy resin and the second organic solvent are based on the total weight of the second organic medium; and

(c) 1-70 wt % of a powder of a high-K material with a K of at least 40;

wherein the wt % of the first organic medium, the second organic medium and the powder of the high-K material are based on the total weight of the dielectric composition.

2. The polymer thick film thermoformable dielectric composition of claim 1 , wherein said urethane resin is a urethane elastomer or a polyester-based copolymer.

3. The polymer thick film thermoformable dielectric composition of claim 2 , wherein said urethane resin is an elastomer.

4. The polymer thick film thermoformable dielectric composition of claim 1 , consisting of:

(a) 20-45 wt % of said first organic medium consisting of 15-35 wt % urethane resin dissolved in 65-85 wt % first organic solvent, wherein the weight percent of the urethane resin and the first organic solvent are based on the total weight of the first organic medium; and

(b) 20-45 wt % of the second organic medium consisting of 15-45 wt % thermoplastic phenoxy resin in 55-85 wt % second organic solvent wherein the weight percent of the thermoplastic phenoxy resin and the second organic solvent are based on the total weight of the second organic medium; and

(c) 20-60 wt % of the powder of a high-K material with a K of at least 40;

wherein the wt % of the first organic medium, the second organic medium and the powder of the high-K material are based on the total weight of the dielectric composition.

5. The polymer thick film thermoformable dielectric composition of claim 1 , wherein the high-K material has a K of at least 100.

6. The polymer thick film thermoformable dielectric composition of claim 5 , wherein the high-K material has a K of at least 500.

7. The polymer thick film thermoformable dielectric composition of claim 4 , wherein the high-K material has a K of at least 100.

8. The polymer thick film thermoformable dielectric composition of claim 7 , wherein the high-K material has a K of at least 500.

9. The polymer thick film thermoformable dielectric composition of claim 1 , wherein the high-K material is selected from the group consisting of barium titanate, lead zirconium titanate, barium strontium titanate and lead lanthanum zirconium titanate.

10. A capacitive switch circuit comprising a dielectric layer formed from the polymer thick film thermoformable dielectric composition of claim 1 , wherein the capacitive switch circuit has been thermoformed.

11. The capacitive switch circuit of claim 10 , wherein the capacitive switch circuitry has been subsequently subjected to an injection molding process.

12. The capacitive switch circuit of claim 10 , further comprising;

(a) a substrate;

(b) a first electrical conductor deposited on the substrate; and

(c) a second electrical conductor;

wherein the dielectric layer is deposited between the first electrical conductor and the second electrical conductor thereby forming a capacitor.

13. The capacitive switch circuit of claim 12 , wherein the first electrical conductor and the second electrical conductor are silver.

14. The capacitive switch circuit of claim 12 , wherein the high-K material used in the polymer thick film thermoformable dielectric composition of claim 1 has a K of at least 500.

15. The capacitive switch circuit of claim 12 , wherein the high-K material used in the polymer thick film thermoformable dielectric composition of claim 1 is selected from the group consisting of barium titanate, lead zirconium titanate, barium strontium titanate and lead lanthanum zirconium titanate.

16. The capacitive switch circuit of claim 12 , wherein the capacitive switch circuit has subsequently been subjected to an injection molding process.

17. A capacitor comprising two electrical conductors separated by a dielectric layer formed from the polymer thick film thermoformable dielectric composition of claim 1 , wherein the capacitor has been thermoformed.

18. The capacitor of claim 17 , wherein the high-K material used in the polymer thick film thermoformable dielectric composition of claim 1 has a K of at least 500.

19. The capacitor of claim 17 , wherein the high-K material used in the polymer thick film thermoformable dielectric composition of claim 1 is selected from the group consisting of barium titanate, lead zirconium titanate, barium strontium titanate and lead lanthanum zirconium titanate.