Abstract
The mechanical characteristic of the solder ball joint on the board level of BGA was studied at certain conditions. The lead-free solder material of 96.5Sn/3.5Ag was chosen to undergo several experiments such as aging effect on strength, strength decaying by the temperature increasing, creep behavior on different temperature or applied loading. Some mathematical model was adopted or built up to fit the experimental data and the observation in the fracture surface by SEM was also proceeded to interpret the fracture mechanism.By the way of applying some different array patterns to shear testing or operating the ball shear test on single solder ball, it could be concluded that the strength allotted to the solder array was uniform. On the aging test, the joint strength of 63Sn/37Pb solder ball decreased by the time passed, and the fracture surface transferred from ductility to brittle. It is significant of difference in strength influenced by different temperature or loading rate and one experimental model was obtained in fitting all the data in good agreement. As to the aspect of creep, one reasonable value of stress exponent (n) or activation energy (Q) was settled on the modified Arrhenius-type power law.