Failure mechanisms of interconnections in drop impact

This study performs experimental tracking of crack propagation (stage II fatigue) in a single solder interconnection during drop impact. A high resolution, highspeed four-point resistance measurement system is used for tracking crack progression. Results indicate that most of the drop impact low-cycle fatigue life of the solder joint is spent in the crack initiation stage. Cross-sections and fractographs show that various mixes of intermetallic and bulk failure are possible within a single joint. Several failure mechanisms are suggested. Comparisons of failure modes are also made between drop impact, quasi-static loading and high-cycle fatigue. A thorough understanding of failure mechanisms is important for the development of failure criteria and life prediction models for drop impact.