Contact degradation in hot/cold operation of direct contact micro-switches

Degradation of gold contacts in micro-switches was studied under an extensive range of operation conditions including high-electric-field ac/dc hot switching, low-electric-field hot switching and cold switching. Tests were conducted in a unique experimental switching operation set-up. Gold micro-contacts were characterized by an atomic force microscope. It was found that a unique material transfer/distribution feature was correlated with specific switching operations. New insights into contact degradation mechanisms of micro-switches were achieved by analyzing contact degradation features under varied operation conditions. Our results indicate that for high-electric-field hot switching, gold atoms are transferred from the ‘anode’ contact to the ‘cathode’ contact via field evaporation; for low-electric-field hot switching, material transfer is induced by transient heat; and for cold switching, contact resistance can be jeopardized by surface contamination and surface roughness if contact force is low.