Fretting corrosion of gold-plated connector contacts

Abstract

Base metal contacts in separable electronic connectors that are subjected to vibration, mechanical shock or thermal fluctuations often develop a high contact resistance due to fretting corrosion. The degradation of contact behavior is due to the accumulation of insulating oxides at the interface. Gold-plated contacts may also fail by fretting if the finish is worn through. A study of base and electroplated gold contacts with the gold in a range of thicknesses revealed that transfer dominates fretting and that an equilibrium distribution of a contact metal with an underplate and a substrate is attained which is the same for both members, although they may initially have been different. A thin gold deposit on a nickel underplate maintains a low contact resistance when the opposing member is solid gold, because nickel promotes adhesive transfer of the gold. However, solid 70Au-30Ag alloy transfers less well, thereby destabilizing the contact resistance of the system. Lubrication is of benefit as it lowers the gold wear rate, which delays the appearance of base material. Solder plate readily transfers to a mating gold contact, thus making both surfaces base, with rapid escalation of the contact resistance.