Electronic phenomena on switch contacts

Experimental studies presented in this paper indicate that stationary and sliding contacts of practical applications may exhibit nonlinear behaviour. This can be attributed to the microstructures formed on the apparent contact surface. The physical phenomena which appear in this case seem to be dependent on the degradation of the contacts and the increase in thickness of the overlayers. The conductivity through thin interfacial layers (<50 /spl Aring/) is attributed to quantum mechanical tunnelling and through thicker interfacial layers to field emission and impact ionisation. The well-established metal-insulator-metal theory provides the required theoretical basis for the interpretation of the measurements. Based on the above, an equivalent circuit is proposed, which is valid for both stationary and sliding contacts.