Anand Parameter Test for Pb-Free Material SnAgCu and Life Prediction for a CSP

Abstract

A series of tensile tests for Pb-free solder material 95.7Sn3.8Ag0.5Cu have been conducted under a wide range of temperatures and constant strain rates to obtain the required data for fitting the material parameters of Anand model. Based on these test results, empirical equations of the tensile strength, elastic modulus and yield stress are fitted as the functions of temperature. It is found that the temperature and strain rate have demonstrated crucial effects on tensile and creep properties of SnAgCu solder material. The test results have also displayed certain viscoplastic behavior, temperature dependence, strain rate sensitivity and creep resistance. A procedure for the determination of Anand material parameters through data fitting is proposed to find nine Anand constants. Three-dimensional finite element analysis has been applied to predict the fatigue life of solder joints under thermal cycling conditions. Finally the solder joint life prediction and comparison of Pb-free material 95.7Sn3.8Ag0.5Cu and standard Pb material 62Sn36Pb2Ag solder for a CSP are examined.