Tensile properties and drop/shock reliability of Sn-Ag-Cu-In based solder alloys

Over the past few years, the Sn-3.0(wt.%)Ag-0.5Cu alloy has become a representative Pb-free solder material in the microelectronic packaging industry. However, Sn-3.0Ag-0.5Cu exhibits significantly poorer performance than eutectic Sn-Pb under high strain rate conditions, such as drop testing. It was previously suggested that a quaternary alloy with the composition, Sn-1.2Ag-0.7Cu-0.4In, is a promising candidate for replacing Sn-3.0Ag-0.5Cu. In this study, Mn was chosen as the minor alloying element in a solder alloy with a new formulation, Sn-1.2Ag-0.7Cu-0.4In, to improve its drop/shock reliability. The drop/shock reliability of the newly developed Sn-1.2Ag-0.7Cu-0.4In-Mn Pb-free solder alloy was examined. The drop/shock reliability of this alloy is discussed using the results of the tensile test at various strain rates and compared with that of Sn-1.2Ag-0.7Cu-0.4In, Sn-3.0Ag-0.5Cu and Sn-1.0Ag-0.5Cu. The results showed that the addition of Mn had a significant effect on the drop/shock reliability.