Abstract: Influence of thermal aging time on the morphology and microstructure of the interfacial IMC for BGA(ball grid array) package between Sn-3.0Ag-0.5Cu lead-free solder ball and Cu interface at 115℃ were investigated. Meanwhile, the shear strength for BGA solder ball was studied and simulated by ANSYS 12.0 finite element software with a non-linear finite element model under two different strain rates. The experimental results are as follows:with the increase of the aging time,the morphology of interfacial IMC changes from dendritic to continuous even lamellar,the thickness of interfacial IMC increases continuously and the shear strength of solder ball gradually decreases. Furthermore,the simulation results show that the larger strain rate will result in the higher shear strength,the higher Von Mises stress,the smaller plastic strain and the higher plastic strain energy density.