Thermo-mechanical stresses within switching contact systems after arcing events

Silver tin oxide (Ag/SnO2) contact materials are widely used in contactor applications. A general trend in this application field is the steadily ongoing miniaturization of switching devices, resulting in growing energy densities to be handled by the contact system. The higher arcing energy densities in such new designs are inducing increased thermo-mechanical stresses in the contact system. As these stresses cannot be measured, FEM simulation was applied to make them visible for heavy duty break arcs. Focus of the presented studies is the temperature dependent elastic and plastic modeling of the intermediate Ag layer and the braze filler. Based on these simulations, improvements in material stress behavior of the complete system (sub-assembly) should be realized.