Study on reliability of Pb40/Sn60 solder joints under dynamic loading

Solder interconnects are commonly used in surface mount technology microelectronics packaging. It is well known that the dominant failure mode for solder joints is thermal fatigue. When semiconductor devices are used in vibrating environment such as in automotive and military applications, dynamic stresses contribute to the failure mechanism of the solder joint and in certain circumstances they can become the dominant failure cause. In this paper a unified constitutive model for Pb40/Sn60 solder joints is developed and then implemented in a finite element dynamic analysis procedure. The purpose of the material model and the implementation is to study the contribution of vibration induced strains to the fatigue life of solder interconnects in low-cycle and high cycle fatigue. The proposed material model, which is based on the Disturbed State Concept (DSC), is used for dynamic analysis of a solder joint.