Contact Resistance Characteristics of Relays Operated in Silicone-Vapor-Containing and Non-Silicone Atmospheres with Different Electrical Load Conditions

Influences of vapors evaporated from an acryl-based non-silicone-type polymeric cured material and conventional silicone-containing polymeric cured materials were evaluated with respect to their effects on contact resistance characteristics of relay contacts at an ambient temperature of 120°C. More specifically, a commercially-available mechanical relay (AgSnIn contacts) was sealed into a metal can with one of these materials, and placed in a heating chamber to operate, at an operating frequency of 0.5 Hz, 40,000 break operations of an inductive DC 14V-1A, 14V-0.4A, 10V-1A, 5V-1A load currents, or a resistive DC 14V-1A load current. Contact resistance values were measured at every 50 operations. As a result, the relays sealed with the acryl-based non-silicone-type polymeric cured material showed no deterioration in contact resistances, irrespective of the load conditions. On the other hand, the relays sealed with the silicone-containing polymeric cured materials showed more significant deteriorations and fluctuations of the contact resistance characteristics, and certain influences of load conditions on their behaviors were recognized.