The increase in high speed, multi-function and high I/O pin semiconductor devices highly demands high pin count, very thin, and high density packages. BGA is one of the solutions, but the package has demerits in package reliability, surface mounting problems due to the PCB warpage and solder joint crack related with TCE mismatch between the materials. On this study to verify the thermal fatigue lifetime of the solder joint FEM and experiments were performed after surface mounting BGA with different solder composition and reliability conditions. FEM showed optimum composition of Ag3.2-Sn96.5 and under the composition minimum creep deformation of the solder joint was calculated, and the thermal fatigue lifetime was improved. In view of temperature cycle condition, the conditions of $-65^{circ}C$to $150^{circ}C$ showed minimum lifetime and t was 1/3 of $0^{circ}C$ to $125^{circ}C$ condition. Test board was prepared and solder joint crack was verified. Until 1000cycle on soder joint crack was observed.