Cermet resistive element for variable resistor

Abstract

An improved resistive element comprises a film-type resistive layer applied to an insulative substrate and then fired. An array of discrete, spaced apart islands of predominantly conductive material is then applied to the resistive layer in a repetitive pattern having predetermined inter-island spacing. The islands have a conductivity that is substantially greater than the conductivity of the resistive layer. Preferably, the islands are of substantially uniform shape and size. In one preferred embodiment, the islands are formed of a conductive thick film ink that is screen-printed onto a cermet resistive layer through an appropriate mask, and then fired. In another preferred embodiment, the islands are formed of a conductive metal that is applied to the resistive layer by vapor deposition, sputtering, or ion implantation through a suitable mask. Either embodiment of the invention provides a resistive element with lower contact resistance and improved contact resistance stability than prior art film-type resistive elements, while maintaining good linearity, setability, and resolution.

Dependencies are inferred from the claim text.