A statistical comparison of gold and palladium-nickel plating systems for various fretting parameters

An electrodeposited plating system of gold over an 80Pd-20Ni alloy is a promising contact material that potentially offers the advantages of thick gold plate at significantly lower cost. This paper presents the statistical and experimental evaluation of various fretting parameters on the contact resistance stability of a simulated separable connector contact interface. The parameters were: gold bath, gold thickness, amplitude displacement, palladium-nickel thickness and current flow through the contact. Statistically, the research found that: gold flashed palladium-nickel is inferior to an equivalent thickness of gold plating; palladium-nickel underplate exhibits different contact resistance characteristics for flash and heavy gold plating thicknesses; and humidity has a significant effect on contact resistance. No statistical difference between the hard and soft gold baths was detected. Additional experimentation of the gold flash thickness found palladium-nickel to be beneficial compared to the gold flash on nickel underplate, and current flow to be detrimental. Hard and soft golds with the palladium-nickel behaved differently with and without current flow. Fretting wear and ultimately fretting corrosion were the dominate failure mechanisms of gold flash systems, with little frictional polymer formation for the palladium-nickel systems, even when the gold flash was worn out.