Study of a Wafer Level Package (WLP) for Surface Acoustic Wave (SAW) Filter

In this paper, a numerical study based on the three-dimensional thermo-mechanical finite element method (FEM) has been conducted to analyze the reliability of SAW filter WLP. The 3D FEM model was firstly evaluated based on a benchmark analysis. The validated model is then applied to perform parametric studies on the effects of package geometry, material properties and the processing conditions on the reliability of the package. The stresses and warpages of the package have been analyzed and the critical failure zones have been pointed out. The results show that the CTE of materials play a key role in the reliability of WLP. The maximum stresses and warpages are very sensitive to the CTE of the materials, especially via, the material of which is copper. In addition, the optimal thermo-mechanical properties of materials have been selected to achieve the minimum thermal stress during wafer bonding process based on the parametric studies.