The importance of the thickness of silver coating in the corrosion behaviour of copper contacts

The deterioration mechanisms of unplated and silver-plated copper contacts subjected to corrosive environments have been studied. The influence of the surface treatment and the silver coating thickness was investigated in a short-time test in a flowing mixture of three gases. The influence of brighteners and chromate passivation of the silver coating was also studied. In addition to contact resistance measurements at different normal loads, Auger electron microscopy was used to study the processes involved. Short-time testing in a flowing mixture of three gases proved to be a valuable means for investigating the performance of electrical contacts. It is concluded that the silver coating thickness is the most important factor in corrosion resistance. Contacts with a thin silver coating behave almost like ground unplated copper contacts.<>