Abstract
When we estimate the fatigue life of lead-free solder joints, we have to conduct FE analysis using a constitutive model which can exhibit mechanical properties of lead-free solder. Previously, we proposed a separate type viscoplastic-creep constitutive model which can describe stress strain curves, stress strain hysteresis loops and stress relaxation curves, with these temperature dependencies and these rate dependencies. In this study, we time-integrated the model implicitly with the Owen and Hinton integration scheme in contrast to our previous explicit time-integration. We implemented the algorithm into finite element analysis code ABAQUS via its user material subroutine UMAT. We analyzed the previous conducted material tests by large width of step-time using the developed program. It was confirmed that the convergency of analysis was improved.
