Improvement of the Mechanical Properties of Sn-Ag-Sb Lead-Free Solders: Effects of Sb Addition and Rapidly Solidified

Abstract

The melt-spun processes of Sn-3.5 wt.%Ag and Sn-3.5 wt.%-Sbx (x = 0.1, 0.3, 0.5, 0.7 and 1.0 wt.%) where analyzed using an x-ray diffractometer, a differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The results revealed that super saturated solid solution and intermetallic compounds (IMCs) were produced during melt-spun processes. The results revealed that there are more changes in thermal properties of these alloys due to structural reasons which are producing from micro-structural changes after Ag3Sn and AgSb Intermetallic compounds formation. The mechanical properties of the ternary Sn-Ag-Sb alloys have been improved after small alloying additions of Sb dramatically and rapidly solidified due to microstructure refining. The solder alloys have been withstand creep deformation as show in their mechanical properties and creep results where the values of stress exponent and activation energy of Sn96-Ag3.5-Sb0.5 were 7.87 and 66.51 KJ/mol respectively which indicate to dislocation climb controlled by dislocation pipe diffusion. It is known that even > 0.1wt% level additions of Sb have significant effects on the microstructure of Sn-Ag solder alloys. Sb suppresses the growth of beta-Sn dendrites in favour of eutectic formation.