Electro-mechanical modelling of multilayer contacts in electrical connectors

Electrical contacts are an essential part of electrical circuits and many reliability problems are related to their failure. The present work uses numerical simulation in view of a better analysis of the electromechanical phenomena, in the case of multilayer electrical contacts. We study a ball/plane contact made of bulk CuZn alloy, protected by a thin Sn surface layer. A coupled finite element analysis is performed to calculate the contact resistance of the device: an elasto-plastic model is used to determine the geometry of the contact area, then an electrical model gives the resulting constriction resistance. Results of simulation are compared to experimental data. The respective contributions of the mechanical and electrical phenomena are analysed. The influence of a nickel underlayer is also examined.