Failure Mode Evaluation of QFP Package Interconnect Structure under Random Vibrations

In this paper, it was investigated that the effect of crack propagation mode and the fracture life of interconnect structure, which is the most severe factor of solder joint reliability in QFP packages, under random vibration loading intended for automotive applications. Furthermore, the effect on the fatigue life of solder joints when the variation due to the degree of solder adhesion is taken into account was also studied. The fatigue life of solder joints was evaluated by using the finite element method to reproduce high-cycle fatigue under random vibration and analyzing the life until crack initiation between solder and lead. In order to investigate the effect of different degree of solder adhesion on fatigue life, three models with different shapes of solder joints were created. As a result, it was found that the shape of the solderjoints, or the degree of solder adhesion on the interconnecting structure, has a significant effect on the occurrence of cracks.