Effects of aging temperature on fatigue life of Sn-3.0Ag-0.5Cu solder joints

Thermal aging effects on the fatigue life of Sn-3.0Ag-0.5Cu (wt%, SAC305) solder joint are investigated. Two series of experiments were conducted: 1) at different temperatures after aging for 72 hours; 2) with different aging time at the cryogenic temperature. The fatigue life of SAC305 solder joint were analyzed statistically by using a modified Weibull distribution model, which takes the thermal aging effect into account and the results agree well with the experimental data. After aging for 72 hours, the longest fatigue life was obtained by aging at cryogenic temperature. With the aging temperature raises, fatigue life decreases. The fatigue life after aging at cryogenic temperature for different aging time was found to decrease with the increasing of aging time. An empirical formula that describe the relation between fatigue life and aging time under the cryogenic temperature was proposed. The fatigue life of solder joints can be increased by aging at cryogenic temperature and the aging time should be controlled to be around 72 hours.