In the last 50 years, lead-contained solder materials were probably the most popular interconnect materials used in the electronics industry. Recently, preventing environmental pollutions, lead-free solders are about to replace lead-contained solders. However, the research of lead-free solders is not satisfactory. Some researchers reported that lead-contained solders have a good fatigue property. But the others published the paper representing the lead-free solders have a longer thermal fatigue life. In this paper, the reason why the reported estimation of lead-free solders life was contrary was studied and the lead-free solders fatigue life was evaluated.
In the present study, 63Sn37Pb, and two type of lead-free solder joint reliability were compared. There are several experimental techniques for life evaluation. In this work, pseudo-power cycling testing method was used. This method is more realistic than chamber cycling methods. and it also cheaper, easier than power cycling methods. Power cycling test was performed in various temperature ranges for evaluating the shear strain effect. And to consider the creep effect, the creep-fatigue test was also performed. To verify and analyze, a nonlinear finite element model was used to simulate the thermally induced viscoplastic deformation of the BGA package solder ball joints.
It was found that lead-free solder joints have a good fatigue property in the low temperature, small strain condition. In the high temperature, large strain condition, lead-contained solders have a longer fatigue life.
