Surface accumulation rate of diffusing species on thin gold electroplates

Abstract

An analysis of the accumulated species on the surface of Co-hardened gold electroplates has been carried out. The samples were aged in a common basement air environment at 85, 125, and 150 degrees C for periods of 1 to 12 months. Different gold coating thicknesses were used: 0.3 and 1.0 mu m on phosphor bronze substrate with or without 5 mu m nickel underplates. The accumulation rates of surface films were evaluated using contact resistance probing. Auger electron spectroscopy was employed to characterize the surface species. The values of contact resistance (CR) recorded are consistent with parabolic growth kinetics and have been utilized to extrapolate estimated lifetimes based on the failure criteria of increases in CR to 20, 50, and 100 m Omega levels.<>