Contact Welding Failure Analysis of Micro Electromagnetic Relays in Electrical Endurance Experiments

Contact welding issues originating from the switching events extremely limit the lifespan and reliability of micro electromagnetic relays. In this paper, the contact welding failure phenomena of micro electromagnetic relays are recurred with the designed model switch. Meanwhile, the variations in contact voltage and contact resistance are recorded explicitly in the electrical endurance experiments, and the extracted contact break duration is used to characterize the contact welding phenomenon. Then, the contact welding failure mechanism is revealed with the help of the evolution of the eroded surface morphology and contact voltage. It is determined that the successive breaking behavior of parallel contact asperities is a threat of contact welding failure. By comparison, a novel designed rod contact with convex hull feature could inhibit the contact breaking delay phenomenon effectively.