Failure Analysis of Metal Oxide Varistor used in Wireless Charger of Automotive Vehicle

Automotive advancement mainly focuses on Personalization, Automation, Connectivity and Electrification (PACE) which includes advancement in wireless and telecommunication domain. Different mobile wireless-charging technologies are being developed in recent automotive trends. This enables the smartphone to start charging simply by placing on the charging pad. The heart of the technology is its Printed Circuit Board (PCB) which contains multiple power-electronics to meet the customer demands. Epoxy moulded chip type Metal Oxide Varistor (MOV) is a widely used in automotive sector. In present study, an in-service failed molded MOV of a wireless charger was received for failure investigation. As per failure investigation, the MOV failed due to puncture type failure which is confirmed by presence of puncture type hole in the ceramic, smooth fracture surface and Ag precipitates in the ceramic matrix. The failure can be prevented by selecting MOVs as per threshold acceptable current limit and load dump factor of the application. Keywords: Failure Analysis, Metal Oxide Varistor, Wireless Charger, Automotive Vehicle, MOV, Materials, SEM/EDS