EFFECT OF OXIDE-FILMS AND ARC DURATION CHARACTERISTICS ON AG CONTACT RESISTANCE BEHAVIOR

In order to confirm that oxide films are the predominant reason for co ntact resistance degradation of Ag contacts operating in normal air co nditions, experiments were performed in mixed nitrogen-oxygen gas with switching inductive load and in normal air condition without switchin g load. Even though the failure rate of contact resistance in nonload conditions is quite low, the strong carbon peak exists in the AES spec tra. While in load condition, the oxygen peak usually occurs in the AE S spectra and the carbon peak is not found in mixed oxygen-nitrogen ga s, although, sometimes in normal air. It is very interesting to note t hat contact resistance degradation is not only dependent on oxygen den sity, but also on the difference of are duration in both the metallic and gaseous phases. The tested results help verify that oxide films do minate the contact resistance behavior of Ag contacts in mixed oxygen- nitrogen gas, as well as in normal air condition.