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Measurement of Thermomechanical Behavior of Solder Joints under Power cycling Condition Using Moire Interferometry

Failure mechanisms exposed by environmental accelerating testing methods such as thermal cycling or thermal shock test, may differ from those at the service operating conditions. While the device is heated up or cooled down evenly on its external surface during environmental testing, real operating powered devices experience temperature gradients caused by internal local heating, components’ different heat dissipation capability, and ambient temperature variation, etc. In this study, a power cycling technique is introduced to better approximate the field operating conditions by activating field failure modes. Power cycling test is performed with different solder joints, that is, lead contained and lead free, and the result is compared with environmental test results. Real time moiré interferometry is applied to measure the global/local thermomechanical behavior of different solder joints during power cycling excursion and compared with thermal cycling case. Effective damage parameter is extracted from the experiment and applied to account for the thermal fatigue life difference for different solder joint composition and accelerating testing conditions.