Vibration reliability test of a PBGA assembly

In order to understand vibration fatigue failures in plastic ball grid array (PBGA) solder joints, a series of constant-amplitude vibration tests of a PBGA assembly were conducted. The test vehicle comprises four 256 I/Os PBGA modules mounted on a printed circuit board (PCB). In the test, the assembly was clamped at two opposite sides on a fixture which was bolted to a vibration shaker, to simulate a boundary condition frequently encountered in practice. The shaker provided a constant-amplitude foundation vibration source for the PBGA assembly. During the test, the PBGA modules were continuously monitored so that the fatigue failure could be detected and the cycles-to-failure of the PBGA modules measured. In this paper, the test set-up and procedures are described, the results regarding the cycles-to-failure of the PBGA solder joints are presented, and the typical vibration fatigue failures of the PBGA solder joints are identified. Some problems regarding vibration testing of PCB assemblies are also discussed. Test results show that the PBGA solder joints are vulnerable to vibration.