An Experimental Technique for Studying Mixed-Mode Fatigue Crack Growth in Solder Joints

Abstract

Failures of solder joints often result from development of cracks under complex mixed-mode loading conditions. In this study, a flexural peel technique was developed to investigate the growth of cracks at the interface between solder and Cu substrate. The technique was based on a tri-layer solder/Cu joints, with the solder layer sand-wiched between two Cu layers of desired thicknesses. Finite element analysis was used to calculate the mixed-mode condition at the crack tip as a function of the thicknesses of Cu outerlayers and the solder interlayer. The application of this technique to studying interface crack growth under fatigue loading is demonstrated for eutectic solder joints.