Capacitance build-up in electrical connectors due to vibration induce fretting corrosion

Fretting degradation is generally recognized as one of the major failure mechanisms for electrical connector systems. The major driver of fretting damage is relative motion at the contact interface, producing material displacement and transfer. For non-precious metal plated contact interfaces, this fretting damage serves to repeatedly expose fresh metal to atmospheric oxidation. The result is a substantial and rapid increase in contact resistance due to a localized buildup of an insulating layer. Relative motion at the contact interface can be induced by thermal expansion/contraction, vibration, or by a combination of the two mechanisms. There has been considerable recent work on this topic, including experimental investigations and model development work. Much of this previous work on fretting degradation has focused on the increase in electrical resistance resulting from the buildup of corrosion products (the insulating layer) in the interface between the blade and the receptacle. However, the physical separation of the blade and receptacle by the corrosion products also produces a capacitance effect that has not been previously explored in detail. The present study seeks to explore this phenomenon and develop an understanding of its significance. An experimental study was performed to investigate the fashion of the capacitance build-up subjected to vibration induced fretting motion. A simple model is also developed which relates the capacitance behavior to connector characteristic, vibration profile and resistance behavior. A series of experiments and simulation studies have been performed to explore the physical behavior of such systems and study the capacitance effects of the insulating layer. Of particular interest is the effect on signal phase and frequency response across the connector interface and how these effects might be employed to monitor the health of connector systems used for communication signals.