Effect of Sb additions on the creep behaviour of low temperature lead-free Sn-8Zn-3Bi solder alloy

Purpose This paper aims to investigate the creep behaviour of the recently developed Sn-8Zn-3Bi-xSb (x = 0, 0.5, 1.0 and 1.5) low temperature lead-free solder alloys. Design/methodology/approach An in-house compressive test rig was developed to perform creep tests under stresses of 20-40 MPa and temperature range 25 degrees C-75 degrees C. Dorn power law and Garofalo hyperbolic sine law were used to model the secondary creep rate. Findings High coefficient of determination R-2 of 0.99 is achieved for both the models. It was found that the activation energy of Sn-8Zn-3Bi solder alloy can be significantly increased with addition of Sb, by 60% to 90 kJ/mol approximately, whereas the secondary creep exponent falls in the range 3-7. Improved creep resistance is attributed to solid solution strengthening introduced by micro-alloying. Creep mechanisms that govern the deformation of these newly developed lead-free solder alloys have also been proposed. Originality/value The findings are expected to fill the gap of knowledge on creep behaviour of these newly developed solder alloys, which are possible alternatives as lead-free interconnecting material in low temperature electronic assembly.