Crystal plasticity finite element study of deformation behavior in commonly observed microstructures in lead free solder joints

• This paper shows a material model development for complex crystal structure of tin.
• The model development is based on experiments, modeling and comparative analysis.
• The results show the capability of CPFE to predict the heterogeneous strain in tin.
• This model can predict the formation of ledges and activity of slip systems in tin.

The anisotropy of the tin phase in a Pb-free tin based solder joint has a significant effect on heterogeneous deformation and therefore, the reliability of solder joints. In this study the ability of crystal plasticity finite element (CPFE) modeling to account for elastic and plastic anisotropy in tin based solder joints was examined using shear deformation applied on a simplified representation of a real microstructure of four specific SAC305 solder balls. Commonly observed microstructures in lead free solders are either single crystals or a particular microstructure with solidification twin relationship with about 55–65° rotations about a common [1 0 0] axis (known as beach-ball microstructure [6]). In this study two different single crystals and two different beach-ball microstructures were investigated using CPFE modeling.Simulation results show the ability of CPFE to predict the heterogeneous deformation due to the anisotropic elastic and plastic properties of tin in lead free solder joints.