Mechanical degradation of microelectronics solder joints under current stressing

Understanding the mechanical degradation of microelectronic solder joints under high electric current stressing is an important step to develop a damage mechanics model in order to predict the reliability of a solder joint under such loading. In this paper, the experiment results for flip chip solder joints under high current stressing are reported. Nano-indentation tests suggest that mechanical property, e.g. Young's modulus, degrades in the localized area where void nucleates during current stressing. The experiments also show that thermomigration due to the thermal gradient within solder joint caused by joule heating is significant during current stressing. A three-dimensional coupled thermal electrical finite element analysis shows the existence of a significant thermal gradient in solder joint during current stressing.