Reverse Engineering of QFN Epoxy Mold Compound Properties using Digital Image Correlation

Knowing the thermomechanical material properties of Epoxy Mold Compound (EMC), especially in its processed state, is crucial for reliability simulations of electronic systems containing Commercially-Off-The-Shelf (COTS) components. However, these thermomechanical properties for COTS components are often unknown. In this work we present a method utilizing temperature dependent strain data obtained via Digital Image Correlation (DIC) and out-of-plane warpage measurements. The proposed approach is first applied in a simulative feasibility study, showing promising results with a maximum deviation of 6.9 % for the determined Young's modulus and CTE before and after the glass transition temperature. For the experimentally measured data of a QFN48 we found unique optima for the thermomechanical properties. Verifying the found values is difficult but we were able to measure the Young's modulus by indentation at room temperature which indicated a deviation of 8 % of the found optima. This promising approach is thus able to extract thermomechanical material properties of COTS components.