Failure analysis of a switching power supply

In present work, the failure analysis was conducted on a switching power supply using various methods including macroscopic morphology, circuit analysis, disassembly morphology, X-ray CT, microscopic morphology, and corrosion product analysis. The results indicated that the MOS tube was the location of the failure in the switching power supply. Additionally, the surface solder of the exposed leads was found to have corroded to some extent due to the influence of corrosion media. Combined with the working principle of enhanced NMOS pipe, the cause of the failure is the switching power supply under the high power board device temperature rise, plus the service environment humidity, the pin corrosion, the pin and the packaging interface sealing performance is reduced, the water molecules in the air into the packaging device, and there is a large electric field inside the MOS tube during the working process. The internal metal of the device was affected by comprehensive factors such as temperature, humidity, chlorine ions, and electric field distribution, leading to electrochemical migration and subsequent breakdown between G and D terminals.