Creep Behavior Of BGA Solder Joints Under Different Loading Method

Because of the advantages, BGA has been extensively applied in the field of electronic packaging. But because the miniaturization tendency of solder joints, durability becomes the focus. This study shows that the main reason of failure of Lead-free is the creep strain accumulation. The creep resistance of solder joint plays a decisive role in assessment. So this paper studies the creep behavior of BGA solder joint under different loading condition, and the mainly work as following.Through loading-unloading mode, the impact of loading parameters to the room temperature creep behavior of SAC305 lead-free solder joint was analyzed. Getting the influence of the loading variables to creep behavior of solder joints at room temperature. The study found that with the increase of the loading time, loading displacement increased, which declinded the unloading residual creep strain. The creep curves of constant load phase had a significant deceleration stage and steady stage. With the increase of loading rate, the creep rate of creep curve deceleration phase decline and unloading creep strain increased significantly. Peak load increased, the creep displacement of constant load phase had little change, residual strain after unloading increased significantly. Compared the influence of loading variables,it found that loading rate and the peak load were relatively important factors. Fitted the results, getting creep strain sensitive index m of lead-free BGA solder joint at room temperature was 0.06434. Compared with solder pieces, BGA solder joints of the value of n increased significantly, and creep resistance increased significantly. And discussed the room temperature creep mechanism of SAC305 lead-free BGA solder joints. To simulate the experimental process by finite elements method. Compared with the simulation results of creep curves and the experimental results, and verified the reliability of the simulation.By way of cyclic loading-unloading, using the finite element analysis software MSC. Marc to simulate SAC305 lead-free BGA solder joint under cycle temperature load. Under cycling temperature load, as the number of cycles increasing, solder joint creep strain accumulation was larger in the heating and cooling process, and the largest cumulative equivalent creep strain will move to the center of solder joints. With the increase of the maximum load temperature, equivalent creep strain and the total equivalent creep strain of solder joint increased. The increase of loading rate and the decrease of the load time of a single cycle of equivalent creep strain and the effects of a total equivalent creep strain.Using finite element simulation software to simulate the nanoindentation process lead-free BGA solder joint, the creep behavior of solder joint under different temperature conditions was analyzed. The study found that temperature strengthen the creep phenomenon, and warming causes softening phenomenon of material.