Effect of in addition on Sn-Ag-Sb lead-free solder system

The present study investigates the effect of 1~5 wt.% Indium additions on microstructure, properties and interfacial IMC's formation of Sn-3Ag-2Sb(SAS) lead-free solder alloys. Experimental results show that addition of indium results in formation of intermetallic compounds of Ag-Sn-In phase and InSb phase. Sn atoms in Ag
₃
Sn compound formed originally in Sn-Ag solder system are replaced by In atoms in SAS-xIn solder system as indium content is increased. A structural and morphological transformation of Ag
₃
Sn to Ag
₃
(Sn,In), Ag
₂
(Sn,In) and finally to Ag
₂
(In,Sn) is confirmed. Meanwhile, transformation of interfacial Cu
₆
Sn
₅
IMC layer to Cu
₆
(Sn,In)
₅
is progressed as the level of In content is increased and accelerated by thermal storage as well.