Solder joint formation simulation and reliability prediction

The fatigue-induced solder joint failure of surface mounted electronic devices has become one of the most critical reliability issues in electronic packaging industry. Solder joint reliability performance has been found to be highly dependent on the solder joint configuration, which, in turn, is governed by bond pad size, alloy material, and lead frame structure, as well as solder reflow characteristics. The objective of this work is to develop numerical models: 1) io simulate the solder joint formation during the reflow process; 2) to determine the stress/strain distribution within the joint; and 3) further to predict the reliability (fatigue life) of the solder joints. The solder joint formation process during the solidification stage can be simulated using the Surface Evolver software tool developed by University of Minnesota. The thermomechanical stress-strain analysis can then be carried out using ANSYS to study selected critical design/manufacturing parameters such as leadframe geometry, pad size and dimensions, solder paste volume, leadframe placement misalignment, etc. This effort also involves the development of interface linking Surface Evolver and ANSYS.