In-Situ Observations of Crack Propagation and Microstructure Evolution in a SAC305/ Cu Solder Joint Using High-Voltage Electron Microscopy

To ensure reliable device manufacture and operation, it is essential to understand the mechanisms of solder joint crack formation and the recrystallisation behavior of solder joint intermetallics and alloys. However, due to difficulties in observing real-time atomistic scale analysis, we still do not fully understand that mechanisms of failure. Here, we developed an innovative in-situ method using high-voltage electron microscopy for observation of microstructural features of a solder joint during deformation. This technique was used to observe events including dislocation formation, recrystallisation, grain rotation and crack formation in a SAC305 alloy soldered on a copper substrate.