Comparison of experimental, analytical and simulation methods to estimate substrate material properties for warpage reliability analysis

Abstract Warpage is a serious reliability issue in ultra-thin packages. Methods and approaches to address warpage and design initiatives aimed at minimizing it are still very preliminary considering the wafer level variations in the substrate material properties, metal line density distributions and process induced variations. In order to design for reliability of the ultra-thin package, it is first essential to have accurate time-efficient simulations that match closely with experimental values. This relies on the accuracy and precision of measurement of the material properties of the package. This study reviews the different experimental and modeling approaches to estimate the Young’s modulus and coefficient of thermal expansion (CTE) and compares the accuracy of warpage simulations using finite element analysis (FEA) by plugging in these different values for E and CTE from the different approaches with the experimental warpage measurements. The digital image correlation (DIC) is proposed as a useful technique to increase the resolution of material properties used as input to simulations and will be evaluated against more time-consuming methodologies.