GB640323A - Metal film resistor - Google Patents

Abstract

640,323. Resistance coatings and deposits; couplings. CONTINENTAL CARBON, Inc. Feb. 20, 1948, No. 5121. Convention date, Feb. 3, 1940. [Classes 37 and 38 (i)] [Also is Group II] A process of constructing a metal film resistor includes the steps (1) coating a non-conductive carrier with a metallo-organic compound comprising an organic resinate of a substantially stable and non-oxidizable metal, for example palladium or platinum resinate; (2) heating the coated carrier to a temperature below the melting point of the resinate to atomically deposit a thin continuous metal film on the carrier; and (3) heating to oxidize the carbonaceous residue remaining after the deposition of the thin film of metal. A ceramic tube 10, Fig. 3, is coated with palladium-resinate 20. The latter may be applied with a suitable solvent such as ketone to reduce the concentration of palladium. The coated tube is dried in air at 20‹ to 25‹ C. and then heated in a temperature ranging from 200‹ to 400‹ C. This treatment effects precipitation of pure palladium accompanied by a residue of carbonaceous ash mixed with the pure palladium as represented at 21, Fig. 4. A second heating of the carrier in a temperature ranging from 400‹ to 750‹ C. oxidizes this residue leaving a thin palladium film 11 firmly bonded to the carrier 10, Fig. 5. Further coatings may be added at different stages. The ohmic value may be varied by grinding a helical groove in the carrier. To furnish the resistor with terminals, Fig. 1, a coating of metal 12, for example colloidal silver fired on at 500‹ to 600‹ C., is formed about the ends of the palladium film 11 and copper bands 13 are then clamped in contact with the silver coating 12.