Experimental Determination and Modification of Anand Model Constants for Pb-Free Material 95.5Sn4.0Ag0.5Cu

A series of tensile tests for pb-free solder material 95.5Sn4.0Ag0.5Cu are conducted under a wide range of temperatures and constant strain rates to obtain the required data for fitting the material parameters of the Anand model. Based on these test results, empirical equations of the tensile strength, elastic modulus and yield stress are fitted as a 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. In order to capture experimental data accurately, a modified Anand model with certain parameters which are the functions of the temperature and strain rate with the quadratic polynomial formula is discussed. Good agreements between the modified model prediction and experimental data have been obtained.