Abstract
In this study, we observed the formation of the Sn-W reaction layer at the interface between Sn-3Ag-0.5Cu solder and an electrolesSni-B/Au plated W substrate. This was done by using repair process which was heat treated by replacing new melting solder. As a result, we confirmed that the Sn-W reaction layers are generated by 10 to 20 times solder repairs. This is repeated on the W substrate with Ni-B at 533K, getting through to the intermetallic compounds such a Sn-W and Sn-Ni-W-Cu at the interface. The structure was analyzed as two layers namely, a Sn:W=1:1 reaction layer, and a Sn:W=7:3 reaction layer. The Sn-W reaction layer shows excellent properties such as solder repair metallization, and is composed by each Sn grain and W grain, which does not show regular crystal structure. Furthermore, M5 edge EELS spectrum of the Sn-W reaction layer were measured with TEM samples, and the Sn-W bonding was analyzed by electron multiple scattering theory of FEFF8.2 calculation code. It was clarified that the Sn-W bond has more interaction with each other than Ni-W bond and W-W bond.
