The effect of stress on the mean time to failure (MTTF) of solder under electromigration

In this paper, we followed the advice of Prof. Tu to investigate the effect of stress on the electromigration behavior of solder. Static electromigration test and thermal cycle test (−55°C - 125°C) with maximum current density of 2×10⁴A/cm2 were performed. In the fatigue test, it was found that the specimens without electricity had the longest MTTF which suggested electromigration may accelerate failure regardless of the stress at entrance of current. While the MTTF of the specimens with tensile stress at entrance was a little longer than those with compressive stress at entrance. During the past 5500 hours of static electromigration test, more than two thirds of the samples from each group failed, it was found that the failure of the specimens with tensile stress at entrance centered on 1000h, 3000h and 5000h while those with compressive stress at entrance to be scattered and the life span seemed shorter.