Claims
- 1. A thick film base metal resistor having a substrate with a resistive paint screened and fired thereon, wherein the improvement comprises:
- (a) blending a tantala glass frit with a tin oxide in the ratio of one part tantala glass frit with three to four parts tin oxide;
- (b) mixing the combined tantala glass frit and tin oxide with a screening agent in the ratio of 25 to 35% by weight screening agent to 65 to 75% of the blend of tantala glass frit and tin oxide to yield a resistive paint;
- (c) screening the resistive paint upon a substrate, and
- (d) subsequently firing the substrate with resistive paint screened thereon in an inert atmosphere at a peak temperature of 900.degree. C..+-.20.degree. C.
- 2. The resistor of claim 1, in which the tantala glass frit and tin oxide are ground to a particle size of ten microns or less.
- 3. The resistor of claim 1, in which the tin oxide is preheated in a reducing gas at a peak temperature of 450.degree. C. to 600.degree. C.
- 4. The resistor of claim 1, in which the screening agent forms no carbon residue when pyrolytically decomposed in an inert atmosphere.
- 5. The resistor of claim 1, wherein the tantala glass frit contains from five percent to twenty-five percent tantalum oxide of the formula Ta.sub.2 O.sub.5, by weight.
- 6. A thick film resistor, made by screening a base metal resistive paint upon a substrate, and firing in an inert atmosphere, which comprises:
- (a) a mixture of glass frit, well blended with from 5 to 25 percent of a tantalum oxide, the mixture melted and reground to form a tantala glass frit therefrom;
- (b) the tantala glass frit then mixed with a tin oxide pre-heated in a reducing atmosphere at a peak temperature of from 450.degree. C. to 600.degree. C.; and a screening agent selected to be substantially vaporized during firing; the tantala glass frit and tin oxide blended in the ratio of 75 to 80 percent tin oxide to 20 to 25 percent glass frit; and further blended with 25 to 35 percent screening agent, by weight, to form the base metal resistive paint therefrom;
- wherein the base metal resistive paint is screened in a desired pattern upon the substrate and fired in an inert atmosphere at a peak temperature of 900.+-.20.degree. C., to form the thick film resistor having a controlled temperature coefficient of resistance within .+-.300 ppm/.degree.C.
Parent Case Info
This application is a divisional application of Ser. No. 705,233 filed Feb. 25, 1985; now U.S. Pat. No. 4,655,965 issued Apr. 7, 1987.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4215020 |
Wahlers |
Jul 1980 |
|
4379195 |
Prabhu et al. |
Apr 1983 |
|
4397915 |
Wahlers et al. |
Aug 1983 |
|
Divisions (1)
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Number |
Date |
Country |
Parent |
705233 |
Feb 1985 |
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