A comparative assessment of gold plating thickness required for stationary electrical 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 palladium, and their alloys, without sacrificing reliability. When the application is in adverse environments, gold plated contact finishes can enhance the reliability of the electrical contacts. However, the failure mechanisms depend strongly on the operating environment and contact plating and are time dependent processes. Numerous investigations on unloaded gold plated surfaces (unmated and tested at non-operating environmental condition) have been performed to simulate the contact failures induced by corrosion. However, no models have been proposed that account for the effects of loading electrically and mechanically on the corrosion process and selection of gold plating thickness. This article describes the study of loaded electrical contacts with the objective of setting up a comparative model between unloaded and loaded electrical contacts, which will improve the understanding of the influence of contact force and applied voltage on the selection of gold layer thickness and finish material. Contact force will improve the performance of gold finishes in stationary electrical contacts and decrease significantly, the gold plating thickness requirements compared to unloaded situation because of its effect on suppression of surface film growth. Voltage will accelerate the growth of surface film and result in the decrease of contact lifetime.
gold plating electrical contacts corrosion kinetics diffusion contact resistance