Validation Experiments for Modeling the Atmospheric Degradation Au-plated Copper

The degradation of electrical connector materials (e.g. gold-plated copper) is often the result of copper sulfidation, which occurs when underlying copper substrate is exposed to atmospheric contaminants via pores in the Au-plating. The objective of this work is to examine the effect of relative humidity on sulfidation and the resulting electrical contact resistance as a function of exposure time. Samples consisted of commercially pure copper (600 grit surface finish) electroplated per ASTM-B-488 to produce a 1.2 micron thick Au plating. The exposure environment was a mixed flowing gas stream consisting of air containing 10 ppb H₂S at 30^oC and relative humidity levels of 70%, 50% and 10%.  Electrical contact resistance (ECR) values were measured as a function of applied load and automatically recorded via a LabView program, allowing for large data sets with a high degree of reproducibility.  In addition to scientific discovery, these data provide calibration and validation for a pore corrosion / electrical contact model that has been developed. The effect of relative humidity level on the sulfidation of Au-plated Cu, corresponding ECR, and an overview of the pore corrosion model will be presented.