Dynamic Recrystallisation and Crack Propagation in a Sn-3Ag-0.5Cu/Cu Solder Joint

If electronics manufacturers and users are to have confidence in the reliability of the solder joints on which they rely, it is essential to have an understanding of the solder joint failure mechanisms and the role of dynamic recrystallisation in failure. However, due to difficulties in real-time atomistic scale analysis during deformation, we still do not fully understand these mechanisms. Here, we report the development of an innovative in-situ method using high voltage transmission electron microscopy (HV-TEM) for observation of the microstructural response of a solder joint to room temperature tensile loading. This technique was used to observe events including dislocation formation, dynamic recrystallisation, grain boundary separation, and crack formation and propagation in a Sn-3wt.%Ag-0.5wt.%Cu (SAC305) alloy joint formed between copper substrates.