The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 23, 1982
Filed:
Oct. 06, 1980
Charles C Kuo, Elkhart, IN (US);
CTS Corporation, Elkhart, IN (US);
Abstract
A method for producing a thick film circuit (30) including a copper conductor pattern (19), thereby obviating the need for expensive precious metal compositions. In the process, a fritted copper paint (16) is applied to a ceramic substrate (18) and fired at a temperature of 850.degree. C. to 950.degree. C. and is oxidized. Concurrently, the paint (16) is adhesively joined to the nonreactive and nonconductive ceramic substrate (18). Next, a resistor paint (20) is applied in overlapping relationship with the air-heated copper conductor pattern (19) and fired at 850.degree. C. to 950.degree. C. The entire unit is then fired in a reducing atmosphere at a temperature of 260.degree. C. to 450.degree. C. to reduce the oxidized copper. The air-fired resistor pattern (21) can either be protected by a coating (40) or unprotected during the reducing atmosphere firing. The essential ingredients of the copper paint (16) are a frit (12) that is non-reducible under a hydrogen atmosphere, a copper powder (10) and a suitable screening agent ( 14). In this new and improved three-step firing process, the copper conductors are compatible with existing ruthenium base resistors.