Creep properties of Sn–Sb based lead-free solder alloys

Full implementation of the new generation of lead-free solders requires detailed knowledge and understanding of their mechanical behavior. This paper reports on structure, thermal and tensile creep properties of Sn–5 wt.%Sb, Sn–5 wt.%Sb–3.5 wt.%Ag, and Sn–5 wt.%Sb–1.5 wt.%Au lead-free solder alloys. The results show that the microstructure of Sn–5Sb alloy is characterized by the presence of cubed intermetallic compound (IMC) of SbSn particles (<5 μm) within β-Sn matrix. The two ternary alloys exhibit additional constituent phases of IMCs Ag3Sn for Sn–5Sb–3.5Ag and AuSn4 for Sn–5Sb–1.5Au alloys. Attention has been paid to the role of IMCs on creep behavior. The tensile creep tests were performed within the temperature range 25–130 °C at constant applied stresses. Activation energy (Q) and stress exponent (n) were determined to clarify the deformation mechanism. This study revealed that the solder alloy Sn–5Sb–1.5Au have potential to gave a good combination of higher creep resistance and rupture time, lower melting temperature and higher fusion heat compared with the other two alloys.