METHOD OF TRIMMING THIN METAL RESISTORS

摘要

A thin metal film resistor (15) of a capacitative graphic tablet is trimmed to make the resistor linear within about 0.25%. Alternating voltage is applied along the resistor by a source (40). The resistance of the resistor is measured at discrete points by a capacitative probe (34) and the resistance readings are stored in a data processor (45). A profile is calculated in the processor from the stored readings and a trim operation is made by an electro-erosion apparatus.