Measuring equipment and measurements of adhesive force between gold electrical contacts

This paper describes the apparatus to measure adhesive force between electrical contacts with micro-sliding and the measurements of adhesive force between gold electrical contacts by this measuring equipment. The electrical contact that is concerned in this paper is mounted on a cantilever supporting arm in a small electromagnetic relay. A straight back-and-forth sliding motion occurs on closed contacts when a relay suffers from an externally applied shock, or on contact follow of closing contact operation. Therefore, this apparatus is designed to give a straight back-and-forth sliding motion to closed electrical contacts. We investigated the measuring accuracy of this apparatus and measured the adhesive force between gold electrical contacts. The following results have been confirmed. (1) The error in determination of contact force from 19.6/spl times/10/sup -3/ N to 1.47 N is less than 1%. (2) The error in measurement of adhesive force from 9.8/spl times/10/sup -3/ N to 1.47 N is less than 1%. (3) At gold contacts under conditions of contact force (0.1/spl sim/0.5 N), and the number (1/spl sim/20 times) and the length (50 /spl mu/m and 100 /spl mu/m) of straight back-and-forth sliding motion, the adhesive force measured by this apparatus has been illustrated to be influenced by the contact force, and the number and the length of sliding motion.