Effects of Microstructural Changes of the Solder Joint Under Thermal Loading on the Life Under Vibrational Loading

抄録

  The microstructure changes of solder joint caused by heat cycle load influence on the life against the thermal cycle loading. The creep characteristic changes were more influential than other parameters such as Young's modulus or yield stress. The thermal cycle loading consists of the heat and repeated mechanical strain. In this study, the effects of the material parameter changes caused by the microstructure change with thermal loading on the life against vibration load are estimated by FEM analysis focusing on the BGA solder joint as an example. The crack initiation caused by the mechanical load depends on the strain at the concentrated point of the solder joint. It has already been reported that the creep strain does not appear in the high strain rate loading such as vibration. The microstructure and material property changes caused by the high-temperature environment are measured. And the effect of the yield stress change on the strain under the vibration load is investigated with FEM analysis. The vibration test of the BGA mounted board with and without pre-thermal loading represented the deteriorated life of the solder joint caused by the thermal loading.