Deformation characteristics of Sn5%Sb solder alloy

Deformation behavior of Sn5%Sb alloy has been investigated at various temperatures from ambient to 423 K from constant load creep, and a recently developed automated ball indentation (ABI) tests. A power law relationship between minimum creep rate and applied stress was obtained from the creep tests with a stress exponent n=5 and an activation energy of 12.6+/-1.1 kCal/mole. A transition from n=5 to n=3 was observed in the low stress region at 473 K. ABI tests showed a power law relationship between strain rate and ultimate tensile stress with a value of stress exponent n=5.4 and an activation energy of 13.0+/-1.8 kCal/mole. Based on the values of the stress exponent and activation energy, a new mechanism of creep deformation is proposed. It is suggested that the rate controlling deformation mechanism is viscous glide of dislocations assisted by dislocation core diffusion. Excellent agreement between creep and ABI data indicates that ABI can be successfully applied for studying the deformation behavior of solder joints in actual components in the electronic packaging industry.