In-situ observations of CU6Sn5 mophological changes at the liquid SAC305/ solid OSP-Cu interface

Solidification is one of the main underlying processes in the development of solder joints. As such, there is widespread agreement that understanding the mechanisms of nucleation and growth during solidification can help in the development of optimal solder alloys. While recent advances in in-situ techniques including synchrotron and electron microscopy have allowed for an increased understanding of these mechanisms there are still unanswered questions, particularly around the behaviour of the liquid/solid interface. In this work we have investigated the CU
6
Sn
5
intermetallic liquid/solid interface in Sn-Ag-Cu alloys with Cu atomic motion through the use of high voltage transmission electron microscopy (HV-TEM) around the liquidus temperature. Application of this liquid/solid interface TEM in-situ observation method has potential for solder alloy developments through controlled solidification ie, nucleation and growth, of liquid alloys.