In-situ study on growth behavior of Ag3Sn in Sn–3.5Ag/Cu soldering reaction by synchrotron radiation real-time imaging technology

The growth behavior of Ag3Sn intermetallic compound (IMC), forming in the Sn–3.5Ag/Cu soldering solidification process, was in situ investigated by the synchrotron radiation real-time imaging technology. Three Ag3Sn growth patterns were observed, i.e., linear, Y and X shape, which were primarily related to the crystal structure of Ag3Sn. The size of linear Ag3Sn was larger than those of other shapes. For each pattern, growth velocity of each direction was almost the same. Competitive growth of Ag3Sn was also found in the early stage of solidification process. Most of Ag3Sn were dissolved and only some of them could grow up to the end.