Strain-Life Behavior in 60/40 Solder

This paper describes low cycle fatigue test run at −50°C, 35°C, 125°C, and 150°C on thin 60 Sn/40 Pb solder joints, tested in simple shear. The low cycle fatigue behavior was found to be a function of the criteria used to define the fatigue life. Different drops in the hysteresis load, measured when a constant plastic strain is being applied, was used to define failure. Not only was the magnitude of the fatigue life a function of the load drop definition for failure, it was also found that the Coffin-Manson low cycle fatigue exponent was a function of this definition. The choice of dependent variable for the curve fitting procedure used to calculate the Coffin-Manson exponent is also considered.