Nonlinear Behavior Study on Effect of Hardening Rule of Lead Free Solder Joint

Abstract

In this paper, the effect of hardening rule on stress and nonlinear strain estimation for lead free solder joint is examined using mechanical fatigue test and FEM analysis. From the results of mechanical shear cyclic test, it turns out that Sn-3. 5Ag-75Cu and Sn-8Zn-3Bi solder show remarkable hardening characteristic of kinematic hardening. Based upon the FEM analytical results with mechanical and thermal cyclic loading conditions, it is shown that the hardening rule may cause 15% error at the most in evaluation of non-linear strain in solder joint and this degree of error will not significantly affect the fatigue strength evaluation of solder joint. And the error of maximum stress in solder joint between the both hardening rules increases to 40% for the mechanical loading case. However, the error in the evaluation of stress and nonlinear strain is 10% or less, when elasto-plas-ticity and creep analysis in which considered the kinematic hardening law in loading and holding time, but the creep only in holding time is carried out. © 2004, The Japan Institute of Electronics Packaging. All rights reserved.