Wear Behaviour of Cobalt-Hardened Gold Coatings Related To Internal Macro-Stresses

Abstract

Electrodeposited gold-coatings are frequently used in the electronic industry due to their low electrical contact resistance and their excellent corrosion resistance. In case of electromechanical devices, like connectors, good wear resistance is equally important. This can be ensured by the codeposition of cobalt during the gold electrolysis process. The internal macro-stresses of such cobalt-hardened gold coatings were measured by X-ray diffraction. It was shown that they are closely related to the wear behaviour of these coatings, and this regardless of the different electrolysis conditions used for the production of the coatings. In the present paper, it will be demonstrated that the combined knowledge of composition, grain size and internal stress of gold-cobalt coatings can help to explain the different wear behaviour of these coatings. As a final result, process parameters could be optimized for maximal wear resistance.