抄録
Recently, environmental pollution caused by lead liquation from the solder in wasted electronic machines has become matter of serious concern. Therefore, a great variety of chemical compositions for the 'lead free solder' have been proposed. To use these 'lead free solder' in electronic packaging, the reliability of the solder joints by those solders to the fatigue failure has to be estimated by the FEM analysis. For the accurate analysis, a constitutive model for the lead free solder alloys has been required. The requirement is not only the precision of simulation but also the reduction of the number of experiments to determine the material parameters because the analysis has to be conducted on the proposed various composites of lead free solder joints. In this study, we show the constitutive model that can divide the inelastic deformation into the plastic and creep parts and its numerical determination method for the material constants by only pure tensile tests under several strain rates. The simulations of the creep and cyclic tension-compression loading using Sn/Ag, Sn/Zn and Sn/Bi solder alloys are conducted to verify the applicability of the model and method to the lead free solder alloys.
