Thermomechanical stress-strain hysteresis of Sn-Bi eutectic solder alloy

This study details a thermomechanical testing technique, used in an on-going program, to measure stress-strain hysteresis of solder joints. The apparatus closely approximates the mechanical conditions solder joints experience in electronics packages subjected to cyclic temperature changes. The test assembly is composed of a small load frame, an insert of differing thermal expansion coefficient, and a solder joint. Strain gages on the load frame and a calibration procedure conducted prior to testing allow shearing stress and strain in the solder joint to be obtained during testing. Some thermomechanical deformation behavior of SnBi eutectic solder is reported and discussed