Anand model and FEM analysis of SnAgCuZn lead-free solder joints in wafer level chip scale packaging devices

• Anand model of SnAgCuZn solders.
• Solder joints reliability of WLCSP device based on finite element analysis.
• Zn can enhance the reliability of SnAgCu solder joints during thermal cycle loading.

In this paper, the constitutive response of SnAgCuZn solder was studied under uniaxial tension. Anand model was used to represent the inelastic deformation behavior of the lead-free solders. The material parameters of the constitutive relations for SnAgCuZn solders were determined from separated constitutive relations and experimental results. In addition, the constitutive model was used to analyze the thermally induced inelastic deformation of the solder joints in wafer-level chip scale packages mounted on printed circuit boards based on finite element analysis. And it is found that the addition of Zn can enhance the fatigue life of SnAgCu solder joint.