We studied the effects of adding various amounts of Sb to Sn-3.5Ag-0.5Bi-6.0In-0.8Cu (SABIC) solder in terms of the phase transformation temperature for the b-Sn and g(InSn 4 ) transformation, mechanical properties such as strength and ductility, and thermal fatigue properties under thermal cycling (-40°C/175°C). With increasing amounts of added Sb, the temperature at which the phase transformation occurred increased. At 150 and 175°C, breaking elongation values of solders as a measure of ductility became the highest for an Sb content of 0.5 wt.%. As the phase transformation temperature increased, deformations of the solder joints after the thermal fatigue test were suppressed. The thermal fatigue properties were best at an Sb content of 1.0 wt.%, at which the phase transformation temperature was greater than 175°C.It is considered that raising the phase transformation temperature to a temperature higher than the maximum operating temperature of electronic devices should be the topmost priority to improve crack extension behavior.