Real time X-ray imaging of soldering processes at the SPring-8 synchrotron

Real time X-ray imaging videos of the entire soldering process for preform solders, solder pastes and BGA solders as well as solder alloy solidification and microstructure characterisation has been achieved over numerous experiments at the SPring-8 synchrotron. This paper overviews the developments of this challenging technique and provides key findings related to understanding the reliability of solder joints. There are large difference when comparing the microstructures and solidification pathways between soldered alloys on Cu substrates (Cu-OSP) and bulk alloy solidification.