An experimental investigation of the metal contacts resistance at initial stages of operation

An experimental procedure is described whose objective is the determination of the thermal coefficient, α, in relation to the crossing resistance for copper contacts which have undergone aging under conditions of real operation (200 h) during which surface degradation was generated in a natural manner. It is clear that at the first stages of reoperation (after a few hours of interruption which allowed the contacts to cool down to room temperature) α becomes negative at high current densities. The experimental results make it possible to conclude that foreign coatings on the contacts (oxides, etc.) appear to have semiconducting behavior, and they support the view that nonlinear phenomena appear during the operation of the contacts