A failure analysis of solder flow in DC-DC power module

A failure mechanism and analysis method of DC-DC power module is presented in this paper. The inside of the DC-DC power module is a PCBA wrapped in molding compound. Because of manufacturing defects, there may be voids between the PCBA and the molding compound inside the modules. The solder on the PCBA may flow into the voids during reflow soldering of the module and bridge between different pads, causing failure. Traditional failure analysis methods, such as 2D X-Ray and chemical unsealing, are unable to accurately locate such defects and can also hinder the exposure of true profiles. 3D X-Ray, C-SAM, and mechanical grinding can be used to effectively locate the failure location, expose the failure morphology, clarify the failure causes, and put forward improvement measures.