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 mu m) within beta-Sn matrix. The two ternary alloys exhibit additional constituent phases of IMCs Ag(3)Sn for Sn-5Sb-3.5Ag and AuSn(4) 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 degrees 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. (c) 2008 Elsevier B.V. All rights reserved.