Lifetime resistance model of bare metal electrical contacts

The performance of a bare metal electrical contact may be seriously impaire d by the formation of surface films in the contact area. The growth of surf ace films is influenced by the anion diffusion process in the contacts. The present paper examines the effects of mechanical contact stress, electrica l voltage drop across the contact area, and environmental temperature on th e him growth in a single contact spot. The electrical resistance of a conta ct spot is examined for some common contact metals, such as aluminum, coppe r, and nickel, subjected to corrosive environments. An equation, based on t he fundamental diffusion mechanism is derived for the life cycle resistance in a contact material as a function of environmental temperature, contact stress and voltage drop across the contact area. Resulting curves of resist ance versus time are similar in trend and shape to curves measured experime ntally by other researchers. This approach also provides a means to gain in sight into the correlation between the lifecycle, electrical contact resist ance, and such key design. variables such as contact normal force, applied electrical voltage, and environmental temperature.