US Patent 7224258 Fine line thick film resistors by photolithography

The present invention is directed to a thick film patterned resistor on a substrate and to a method of forming it. The method involves providing a substrate with opposed surfaces, where one surface is coated with a layer of a resistor composition. A photoresist is applied over the layer of the resistor composition, and a desired pattern in the photoresist is formed, where the pattern leaves certain regions of the resistor composition layer uncovered by the photoresist. The resistor composition layer which is uncovered by the photoresist is etched under conditions effective to leave a mass of loosely bound resistor particles at regions of the resistor composition which are not covered by photoresist. The mass of resistor particles is then removed from the substrate to produce a thick film patterned resistor on the substrate.