Microstructure, mechanical properties, and deformation behavior of Sn-1.0Ag-0.5Cu solder after Ni and Sb additions

Minor alloying addition to solders has been an important strategy to improve the integrity and reliability of Pb-free solders joint. In this study, the effects of 0.06Ni and 0.5Sb additives on the microstructure and solidification behavior as well as the creep properties of Sn-1.0Ag-0.5Cu (SAC105) alloys were investigated. Results show that alloying of Ni and Sb resulted in considerably reduced undercooling, increased eutectic area and extended volume fraction of proeutectic Sn of which the dendritic size was refined. Moreover, with the addition of Ni and Sb into SAC105, significant improvement in creep resistance of (210\%) and (350\%) is realized when compared with the SAC105 solder alloy. Likewise, the creep life time of SAC105 alloys was remarkably enhanced (2-3 times) with the minor alloying additions. An analysis of the creep behavior at elevated temperatures suggested that the presence of hard Ni3Sn4 IMC particles and the solid solution hardening effects which appeared, respectively, in the Ni-doped and Sb-doped alloys could increase the resistance to dislocation movement, which improves the creep properties. (C) 2012 Elsevier Ltd. All rights reserved.