Creep behaviour of composite lead-free electronic solder joints

In an attempt to improve service life of lead-free Sn-based electronic solder joints, compatible reinforcements were introduced by in-situ and mechanical mixing methods. The reinforcements affect the steady-state creep rate and the strain for the onset of tertiary creep of the solder joints. However, neither of these parameters, when considered alone, can be used for evaluating the reliability of solder joints. The Larson-Miller parameter, and a new parameter proposed in the paper, can incorporate test parameters to arrive at a reliability prediction methodology. The role of these reinforcements in homogenising creep strain within the joint is analysed. The observed creep behaviour of these composite solders is discussed on the basis of interfacial bonding strength between the reinforcement and the solder matrix.