Thick film resistance thermometer
AssigneeEngelhard Minerals & Chemicals Corporation
InventorDonald A. Toenshoff
Life of this patent
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Abstract
A folded, highly pure platinum, thick film, path on a ceramic cylindrical substrate provides a high TCR of about 3850 ppm/.degree. C. The path is applied by screen printing a thick film paste onto a substrate and then firing the paste at a time and temperature sufficient to bond the path to the substrate and to produce a TCR of at least about 3850 ppm/.degree. C. The paste is comprised of about 20% by weight of an organic carrier into which 80% by weight of particles have been mixed. The particles are 96% by weight platinum particles of less than about ten microns size and 4% by weight of a contaminant-free vitreous glass frit of less than ten microns size.
Claims9
A method of fabricating a stable thick film having a high temperature coefficient of resistance and a uniform change of resistance with temperature, which comprises
- (a) preparing a paste comprising substantially non-agglomerated platinum powder having a purity of at least 99.9%, a substantially contaminant-free frit, and an organic vehicle;
- (b) applying said paste as a continuous thick film strip onto a ceramic substrate;
- and
- (c) firing said strip at a temperature of at least 1450.degree. C. to produce a TCR of at least about 3850 ppm/.degree. C. in the fired film.
A method of fabricating a resistance thermometer utilizing a stable thick film resistence path having a high temperature coefficient of resistance and a uniform change of resistance with temperature which comprises
- (a) preparing a paste comprising substantially non-agglomerated platinum powder having a purity of at least 99.9%, a substantially contaminant-free glass frit, and an organic vehicle, said paste containing from about 4 to 8% by weight of said frit based on the total weight of solids;
- (b) applying said paste as a continuous thick film strip onto a ceramic substrate;
- and
- (c) firing said strip at a temperature of at least 1450.degree. C. to produce a TCR of at least 3850 ppm/.degree. C. in the fired film, and to effect a resistance change of less than 1.degree. C. in equivalent degrees.
Dependencies are inferred from the claim text.