A comparative assessment of gold plating thickness required for stationaryelectrical contacts

There is considerable interest in the corrosion control of thin gold plated contact surfaces of consumer electronics products. This originates in the desire to minimize the use of costly gold and other precious metals, like p alladium, and their alloys, without sacrificing reliability. Wh,, the appli cation is in adverse environments, gold plated contact finishes can enhance the reliability of the electrical contacts. However, the failure mechanism s depend strongly on the operating environment and contact plating and are time dependent processes. Numerous investigations on unloaded gold plated s urfaces (unmated and tested at non-operating environmental condition) have been performed to simulate the contact failures induced by corrosion. Howev er, no models have been proposed that account for the effects of loading el ectrically and mechanically on the corrosion process and selection of gold plating thickness. This article describes the study of loaded electrical co ntacts with the objective of setting up a comparative model between unloade d and loaded electrical contacts, which will improve the understanding of t he influence of contact force and applied voltage on the selection of gold layer thickness and finish material. Contact force will improve the perform ance of gold finishes in stationary electrical contacts and decrease signif icantly, the gold plating thickness requirements compared to unloaded situa tion because of its effect on suppression of surface film growth. Voltage w ill accelerate the growth of surface film and result in the decrease of con tact lifetime. (C) 1999 Published by Elsevier Science Ltd. All rights reser ved.