The purpose of this study is to develop an assessment method for drop impact reliability of BGA solder joints. In this paper, the dynamic deformation behavior of PCB is examined to evaluate the dynamic fracture of solder joints, where a free fall drop-impact test was used, and explicit-based FEM code LSDYNA was used to study the basic behavior of the drop-impact test, and the effects of falling angle on the dynamic behavior of PCB were discussed. As a result, it was confirmed even if collision angle is very small, the dynamic deformation of PCB was drastically affected by the collision angle. In this study, the authors proposed that the dynamic behavior can dramatically be improved by attaching a hemisphere on the jig bottom to obtain stable dynamic deformation of the PCB. Furthermore, in case of that the PCB flexural rigidity was changed, the optimal test jig was designed so that the PCB and the jig for a drop test might not cause resonance vibration. Generally, the crack growing assessment and drop impact strength evaluation for solder joints were studied by a fine meshing FEM model, nevertheless it causes a rapid augmentation of calculation cost. In this study, the authors proposed a new method of transient response analysis by utilizing implicit based FEM analysis code to drop the calculation cost of impact study. It was shown that the present method can accurately simulate the dynamic behavior of BGA packaging including the time histories of the deformations and stresses, and it can drop the CPU time to about one tenth of that of explicit based analysis code.
Performance on the drop impact test of the cone capsule shaped portable tsunami lifeboat using penalty method contact analysis
