The Effect of Voids on Thermal Reliability of BGA Lead Free Solder Joint and Reliability Detecting Standard

Recently, there have been serious debates about whether Pb should be removed from solder joint, in view of environmental problems. These debates have now developed to the extent that a remarkable movement to establish regulations for the removal of Pb has emerged, especially in European countries and Japan. Therefore, many studies have been aggressively undertaken to develop technologies for replacing Sn-Pb solder with lead-free alternative. From the results obtained so far, it has been proven that the fatigue life of lead-free solder joints is almost equivalent to that of Sn-Pb eutectic solder joints. However, a new problem is that voids are easily formed in lead-free solder joints, and the effect of the voids on the fatigue strength of solder joints has attracted attention. In this study, by using mechanical fatigue test, the effect of voids on the fatigue reliability was investigated, and the detailed fatigue behavior in lead-free solder joint with voids was examined. Until now, it was confirmed that quantitative evaluation of fatigue life of solder joints with the voids could be enabled by FEM analysis. And the experimental approach and the effect of the various positions, sizes and number of voids on the fatigue reliability were studied