There is continued concern over the ability of SMD solder joints to survive in the harsh operating environments endured, for example, by automotive and aerospace products. This paper will review the techniques available for analysing solder joint fatigue behaviour and then describe a software tool designed to allow estimation and comparison of the thermal fatigue life of solder joints exposed to a complex operating profile. The modelling technique takes account of the large changes with temperature of the solder alloys stress/strain‐rate behaviour and also the complex geometry of the component/solder/PCB assembly, whilst avoiding the very high cost of non‐linear finite element analysis. This is achieved by first performing a linear stress analysis of the assembly in order to determine its compliance, and then using this compliance estimate in the solution of a non‐linear differential equation describing the relationship between temperature, stress and strain‐rate in the joint. The technique has been implemented as a software package known as ECLIPS—Electronic Connection Life Prediction System. This software package will run on a workstation or PC and has been shown to give results very close to those from non‐linear finite element analysis, but at approximately 1/20th of the cost.
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