Galvanic Plating of Electrical Contacts – Process and Properties

In this dissertation, approaches to enhance the performance and to increase the lifetime of electrical contacts with galvanic plating by modification of galvanic process are investigated. Research is conducted on tin, silver and gold platings. The influence of contact geometry, plating thickness of tin, normal force, temperature, fretting amplitude and the oxygen partial pressure on the lifetime of the tin plated electrical contacts is studied. Then a novel plating system with a Cu/Sn multilayer is developed. The effect of plating parameters on the lifetime of electrical contacts is investigated. The results demonstrate that the Cu/Sn multilayer system has great potential for prolonging the lifetime of non-noble materials plated electrical contacts. For the silver plating, a methodology to predict the wear process accurately is established and validated. Moreover, a novel method is used to fabricate Ag@Al2O3 nanoparticles with a core/shell structure via galvanic process. When co-depositing with these nanoparticles, the hardness of the modified silver plating is improved and the lifetime of the produced electrical contacts is prolonged. For the gold plating, the main task is to reduce the consumption of the gold, while not degrading the performance of the plating. Two methods are used: optimization of the content of the alloying element in the gold plating; co-depositing the plating with self-fabricated nanoparticles. Hard gold platings display lifetime improvement compared to the pure gold plating. The Au-Fe plating has a favorable alloying content. The Au-Co plating shows no great difference in the lifetime within a wide alloying content range. When co-depositing with core/shell structure nanoparticles, the lifetime of the gold plating is significantly prolonged.