Failure Analysis of Solder Joint Cracking in a CBGA Assembly Applied for Aviation Equipment

Board-level thermal-mechanical reliability is one major concern in CBGAs. A typical early fault case of some aviation equipment was studied in this paper. The failure phenomenon was manifested as malfunction of the main board in the flight control computer. The results of fault location showed that there was interconnection failure in the CBGA module in the main board. A serial of experimental technologies were used for the failure analysis, such as 3D X-ray inspection, microsectioning, optical microscope, scanning electron microscope (SEM), etc. The results showed that some Pb37Sn63 solder joints’ through cracking in the CBGA assembly was the immediate cause of the equipment’s malfunction. The main reason for the cracking was thermal-mechanical fatigue with microstructure coarsening degradation, resulting in early failure of the main board. It is suggested to carry out components’ board-level application verification in aviation equipment and other high reliability field.