Polymer thick film resistor compositions

• US 5,470,643 A
• Filed: 06/15/1994
• Issued: 11/28/1995
• Est. Priority Date: 09/15/1992
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Dorfman, Jay R.
• Primary Examiner(s): Nakarani, D. S.
• Assistant Examiner(s): LE, HOA T
• Application Number:
  US08/260,503
• Time in Patent Office: 531 Days
• Field of Search: 428/323, 428/328, 428/340, 428/206, 428/208, 428/329, 428/331, 428/412, 428/411.1, 428/473.5, 428/474.4, 428/480, 252/502, 252/511, 252/514, 524/439, 524/440, 524/441, 524/495, 524/496, 524/611
• US Class Current: 428/206
• CPC Class Codes: H01C 7/005 Polymer thick films
• CPC Class Codes: Y10T 428/24893 including particulate material
• CPC Class Codes: Y10T 428/24909 Free metal or mineral containing
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide
• CPC Class Codes: Y10T 428/259 Silicic material

Abstract

A polymer thick film resistor composition is disclosed which comprises: (1) finely divided particles of a conductive metal having a surface area of 0.3 to 3.0 m² /g; (2) finely divided particulate material having a surface area greater than 100 m² /g; (3) a thermoplastic resin; dissolved in (4) an organic solvent having a volatility rating of 10,000 to 50,000; wherein the composition is substantially curable within 2.5 minutes by heating to a temperature of 135° C., and further wherein the volume ratio of particulate material to resin is at least 3.5, and the weight ratio of solvent to resin is 3 to 5.

Claims

1. A polymer thick film resistor composition consisting essentially of:

(1) finely divided conductive metal particles having a surface area of 0.3 to 3.0 m² /g,

(2) finely divided material non-metallic particles having a surface area greater than 100 m² /g, said particles (a) being chemically inert and (b) having a conductivity substantially less than the conductive metal, and

(3) a thermoplastic phenoxy resin dissolved in an organic solvent having a volatility rating according to ASTM Test D 3539-87 greater than 10,000 seconds to 90% evaporation, wherein the composition is substantially cured within 2.5 minutes by heating to a temperature of 135°

C., and the volume ratio of non-metallic particulate material to phenoxy resin is at least 3.5, and the weight ratio of solvent to phenoxy resin is 3;

1 to 5;

1.

2. The composition of claim 1 wherein the conductive metal is selected from the group consisting of silver, gold, copper and mixtures thereof.

3. The composition of claim 1 wherein the conductive metal has a surface area of 0.7 to 1.3 m^2/ g.

4. The composition of claim 1 wherein the non-metallic particulate material is selected from the group consisting of carbon, silica, alumina and mixtures thereof.

5. The composition of claim 1 wherein the non-metallic particulate material has a surface area greater than 200 m² /g.

6. The composition of claim 7 wherein the solvent has a volatility rating of 10,000 to 50,000 seconds to 90% evaporation.

7. A resistive element comprising a substrate having printed thereon a layer of the composition of claim 1, said layer having been heated to effect removal of the solvent and conversion of the composition to a solid state.

8. The composition of claim 1 suitable for fabricating the resistor element of a voltage indicator comprising:

(1) finely divided silver particles having a surface area of 0.3 to 3.0 m² /g,

(2) finely divided electrically conductive carbon particles having a surface area greater than 100 m² /g, and

(3) a phenoxy resin dissolved in

(4) an organic solvent having a volatility rating according to ASTM Test D 3539-87 of 10,000 to 50,000 seconds to 90% evaporation;

wherein the composition is substantially cured within 2.5 minutes by heating to a temperature of 135°

C., and the volume ratio of carbon to phenoxy resin is at least 3.5, and the weight ratio of solvent to phenoxy resin is 3;

1 to 5;

1.

9. A polymer thick film resistor composition consisting of:

(1) finely divided of electrically conductive carbon particles having a surface area greater than 100 m² /g, and

(2) a thermoplastic phenoxy resin dissolved in

(3) an organic solvent having a volatility rating according to ASTM Test D 3539-87 greater than 10,000 seconds to 90% evaporation,

wherein the composition is substantially cured within 2.5 minutes by heating to a temperature of 135°

C., and the volume ratio of carbon to phenoxy resin is at least 3.5, and the weight ratio of solvent to phenoxy resin is 3;

1 to 5;

1.

11. The composition of claim 9 wherein the solvent has a volatility rating of 10,000 to 50,000 seconds to 90% evaporation.

12. A resistive element comprising a substrate having printed thereon a layer of the composition of claim 9, said layer having been heated to effect removal of the solvent and conversion of the composition to a solid state.

10. The composition of claim 19 wherein the carbon particles have a surface area greater than 200 m² /g.