Influence of oxygen concentration on contact resistance deterioration of Pd contacts due to mechanochemical reaction

Contact resistance deterioration takes place due to the formation of palladium oxide by mechanochemical reaction. In previous papers it was reported that under the condition of no influence of water vapor or organic gases, palladium oxide was formed even when oxygen concentration was less than 0.001% and the rate of palladium oxide formation became slower with lower concentration. In this paper, influence of oxygen concentration on this phenomenon is studied further. With lower oxygen concentration, the saturation phase becomes unstable because saturation value rises up and falls down again and again. But the maximum value agrees with the saturated level, therefore the saturated level is not influenced by the oxygen concentration when oxygen concentration is over 0.026%. But when a moving contact is uppermost, palladium oxide is widely distributed around the contact spot and the saturated level tends to be unstable.