Making contact to aged surfaces

A Monte Carlo analysis of aged crossed rod copper contacts is conducted to evaluate the effects from a number of variables such as film thickness, contact force, microhardness and geometry. The analysis is conducted using two models that employ material properties and design parameters as constraints in a statistical model of degradation. It is shown, using a power law model to describe the surface concentration of oxides, that the degradation model can be calibrated to produce results that show good agreement with a wide range of laboratory data. It is found that the observed difference in performance of soft and hard copper contacts can be explained within the framework of the degradation model. It is concluded that the mechanism which causes oxide accumulation in the surface layer is affected by microhardness in a way which is less favorable to the performance of soft copper contacts.<>