Evaluation of the Stress and the Strain Based on the Principal Stress Plane in Microscopic Region for the Indentation test

Abstract

For accurate evaluation of the reliability of electronic package, FEM analyses considering the creep deformation of solder joint in-situ should be conducted. It is well known that the indentation creep test has an advantage to evaluate the creep deformation in microscopic region although there are the problems. In case of the lead free solders generally used for the solder joint, the transient creep deformation should be measured by the indentation test. The transient creep strain occurs in the indentation process. Therefore, it needs to separate the strain into the elastic-plastic strain and the creep strain. In this paper, the method to obtain the stress-strain relation using the indentation test is proposed by using the numerical test. The stress-strain curve estimated by proposed method well coincides with the stress-strain curve of the nodal solution.