Influence of Oxygen Partial Pressure and Fretting Amplitude onthe Lifetime of Electrical Contacts
Electrical contacts are fundamental components which transfer the current and signals in electromechanical systems.The reliability of the electrical contacts influences the system reliability greatly, in the light of their large quantity.In order to improve the performance of electrical contacts, plating is generally applied on the base material.Tin plating is widely used due to its good solderability, corrosion resistance and low cost.Fretting corrosion is one of the most critical failure mechanisms of tin-plated electrical contacts enduring relative micro-motions.During operation, the tin plating is worn, generating wear debris.Since tin is a non-noble metal, its wear debris will be oxidized to form an insulating layer after long-term use.In many power semiconductor components, the housing is firstly pumped to a vacuum condition, and then filled with nitrogen, which leads to a reduced amount of oxygen, a lower oxygen partial pressure and a longer mean free path of oxygen molecules.This service condition influences the lifetime of the tin-plated electrical contacts significantly, since a longer mean free path of oxygen molecules corresponds to a lower collision possibility of oxygen molecules to the tin surface, which can retard the oxidation process.Moreover, the two parts of electrical contacts can experience different amplitude in relative micro-motion, which also has an effect on the lifetime.In order to investigate the influence of oxygen partial pressure and fretting amplitude on the lifetime of electrical contacts, measurements are conducted with a fretting corrosion test device under various vacuum degrees and fretting amplitudes.A theoretical model illustrating the relationship between the lifetime of electrical contacts and pressure is established and verified by the measured results.The lifetime of electrical contacts in fretting corrosion tests is prolonged with a lower pressure and larger fretting amplitude.
Amplitude electrical contacts fretting corrosion tin plating vacuum
Haomiao Yuan Jian Song
Precision Engineering Laboratory Ostwestfalen-Lippe University of Applied Sciences and Arts, Lemgo, 32657, Germany
国际会议
江苏苏州
英文
33-37
2019-11-04（万方平台首次上网日期，不代表论文的发表时间）