Failure analysis and case study on welding failure of BGA

A failure analysis of a BGA false welding was discussed in this paper. Some techniques used in the analysis process are introduced respectively. To find the regularity of the fault location, visual inspection and X-ray inspection were used to determine the failure location. To clarify the characteristics of the failure area, the height difference of BGA was measured by laser confocal microscope. The morphology of each solder joint was analyzed by using cross-section, and it was found that the solder joints at the failure area were elongated. FIB and SEM analysis are used to eliminate the cause of insufficient thickness of OSP on the PCB pad. Finally, the shadow moire analysis verified the excessive warpage of the BGA during the welding process. Base on all above analysis, the root cause of the failure is due to excessive warpage and deformation of the BGA substrate. This article provides several innovative analysis methods for the failure analysis of the false welding, and provides some new ideas for this kind of failure analysis in the industry.