Electrical effects of fretting connector contact materials: A review

Abstract

The fretting of electrical contacts can lead to unacceptable increases in contact resistance. Although this phenomenon was recognized for many years, considerable new work has been published recently on its occurrence and possible effect on the reliability of separable electronic connectors. The reason for these studies has been economic. Escalation in the cost of gold, the preferred contact material because of its nobility, stimulated interest in potential replacement metals such as Sn-Pb solder plate and palladium. Unfortunately, connectors with these replacement metals are prone to fretting failure. In this paper the fretting of electrical contacts is reviewed on the basis of work carried out by the present author and by other investigators. Included are a discussion of mechanisms of transfer, wear, oxidation and frictional polymerization which apply to the fretting of contacts and of the influence of operational parameters such as cycle rate and force on contact resistance, a survey of materials whose fretting behaviors have been determined and an analysis of the role of lubricants in controlling fretting degradation.