Numerical study on current and thermal distributions of electrical contacts by FEM

Accurate determinations of contact resistance (which contains constriction and film resistance) and temperature rise are most conventional and important issues of electric conduction devices. This paper investigates coupled analysis of current and thermal distributions of Ag electrode by FEM. Intended final results are to obtain constriction resistance and temperature values. Contact areas (a-spot) of spherical and flat shaped Ag electrodes are discretized to a large number of narrow finite elements. Firstly, current density distributions in each element are calculated by FEM, and contact resistance values are obtained from the impressed current and electric potential difference between the anode and cathode. Compared with the theoretical results by R. Holm's equation for constriction resistance, calculated contact resistance values of several a-spot radii show fine agreement. Local Joule heat distributions are also obtained. Moreover, thermal distributions in the electrodes are shown as the calculated results. As a quantitative verification, tendency of maximum temperature of the calculated results shows good agreement with phi-thetas theory by R. Holm.