Failure analysis of the electromagnetic relay contacts

•Comprehensive study is conducted to investigate the effects of long-term storage on electromagnetic relay.•XPS analysis is used to help ensure the contamination on the contact surface.•Mechanical damage and inorganic and organic pollution are the mean reasons for degradation during storage.

It is a common phenomenon that electronic components may fail after long-term storage. Users fed back that contact resistance value of several electromagnetic relays increased during the process of storage. In order to figure out the root causes of storage failure, failure analysis has been conducted in this study. Visual inspection and internal examination were carried out to observe the mechanical damage. Seal test and internal gas analysis were conducted to illustrate the situation of package and internal gas composition. The morphology and composition analysis of electromagnetic relay contacts were conducted by SEM, EDS and XPS. The results of all tests and inspections demonstrate that mechanical damage, inorganic contamination and organic contamination are the causes for the increase of contact resistance value.