Microstructural Evolution of Sn-Ag-Sb Solder with Indium Additions

Abstract

The effects of 1 wt.%, 5 wt.%, and 10 wt.% additions of indium (In) on the microstructure and compound morphology of Sn-Ag-Sb lead-free solder joints were examined. The results showed that In prompts the formation of Ag 3 (Sn,In), Ag 2 (In,Sn), and InSb compounds within the solder matrix. As the amount of In was increased, the Sn atoms in the Ag 3 Sn compound were gradually replaced by In atoms, prompting a transformation from Ag 3 Sn to Ag 3 (Sn,In) and finally to Ag 2 (In,Sn). This transformation occurs more readily under high-temperature conditions. The Ag 2 (In,Sn) compound formed in Sn-Ag-Sb-xIn/Cu solder joints was found to have either a leaf-like morphology or an antler-like morphology. Finally, with In additions greater than 5 wt.%, the Cu 6 Sn 5 interfacial compounds in the solder/Cu joints transformed into Cu 6 (Sn,In) 5 .

Effects of Antimony and Indium Addition on Wettability and Interfacial Reaction of Sn-3.0Ag-0.5Cu Lead Free Solder on Copper Substrate

“…This result is consistent with prior reports of Sb addition into the Bi-2.6Ag-0.1Cu-xSb solder alloys [11]. Lee et al [14] reported that the pasty range temperature lower than 30 o C was proven to be advantageous for a solder in manufacturing. Moreover, the undercooling of SAC305, SAC305-0.5In, SAC305-0.5Sb and SAC305-0.5InSb solder alloys were 30.61, 25.49, 12.28 and 24.29 o C, as shown in Table 3.…”