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. 19, 1980
Filed:
Sep. 09, 1976
David C Hill, Attleboro, MA (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
An improved electrical resistor device is made by molding a body of ceramic material of positive temperature coefficient of resistivity so that a plurality of passages extend in a pattern in spaced side-by-side relation to each other between opposite ends of the body. In molding the body, lands or abutments of resistor material are formed around the ends of alternate body passages at one end of the body and similar lands or abutments are formed around the ends of the other passages at the opposite end of the body. A band of masking material is applied to the sides of the body extending around the body leaving the ends of the body, and bands of the body side surface adjacent each end of the body, free of masking material. The masked body is then immersed in a coating bath for simultaneously coating the inner walls of the body passages, the ends of the body, and the unmasked bands of the body side surface with an electrically conductive ohmic contact material. Preferably, the ohmic contact and masking materials are selected to be impervious to reducing atmospheres and the like for protecting masked and coated portions of the ceramic resistor material against degradation in such atmospheres. Preferably, the ends of the body are immersed in an additional coating bath or are otherwise treated for coating at least the unmasked bands of the body side surfaces with a material characterized by low electrical contact resistance. Thereafter, the outer ends of the abutments are abraded for removing coating materials from the ends of the abutments. In this way, ohmic contacts in alternate body passages are connected together at one end of the body to form a first device terminal having low contact resistance while ohmic contacts in the other body passages are connected together at the opposite end of the body to form a second device terminal. Alternatively, the ends of the body abutments are masked prior to immersion of the body in the contact coating baths for permitting omission of the noted abrading step.