Failure Analysis on the BGA Solder Joint

The analysis process and methods of a failure BGA solder joint have been studied by a failure analysis case for an actual BGA package sample with XRD, cross section analysis and SEM&EDS analysis. The analysis results show that the cracks are the main failure causes of the BGA solder joints. The position of cracks appeard between the IMC and PCB pad and the interface of solder and IMC. The main reason of cracks is that excessively thick and irregular Sn-Ag and Sn-Cu IMC reduced the mechanical robustness of the solder joints and when the solder joints were subject to external stress, cracking occurred. The contribution of failure analysis to quality control of BGA mounting was also displayed.