Reliability assessment and field failure predictions - a prognostic model for separable electrical contacts

The ongoing demand in providing reliability to separable electrical contacts involves mandatory measures for the discrete nature of the contact interface as well as the necessity of fulfilling a broad variety of product requirements. The formation of real and conductive contact areas controls the reliability and efficiency of an electrical contact. These processes depend on a great number of independent or interrelated factors. The variety of these factors can be divided into (a) performance factors governed by the operating conditions and (b) design-technological factors determined by fabrication characteristics of the contact unit. The present study derives a model to determine the influences of the design- technological factors on the reliability and quality of electrical contacts. Together with the lifetime tests and their statistical evaluation it is possible to deduce fault rates combined with the probability of failure and reliability for a newly designed contact unit. Furthermore detailed surface analytical investigations of the contact zone were performed to identify the occurrence of physical and chemical processes which are influencing the state of the contact interface and, finally, the contact resistance and reliability.