Effect of Effective Curing Shrinkage of EMC on Strip Warpage During IC Encapsulation Process

Abstract

Using numerical simulation to create a digital twin for process evaluation is vital for sustainable and intelligent manufacturing, which can predict manufacturing failures and design for optimization in advance. Material characterization plays a crucial role in a convinced numerical simulation creation. Encapsulation-induced warpage is a vital issue of integrated circuit (IC) packaging. A strip of flip-chip chip-scale package (fcCSP) was chosen as the test vehicle. A Moldex3D simulation model was developed to evaluate the encapsulating process from filling to curing to cooling. The effective curing shrinkage of epoxy molding compound (EMC) can be derived from the encapsulating process. The material properties of EMC, including effective curing shrinkage, thermal shrinkage, and viscoelasticity, are considered in the warpage simulation. The simulation result correlates well with the experiment result. Regarding package design, the effect of various factors on the warpage was investigated using Taguchi’s method. Several component sizes, material parameters, and process parameters were selected as the design factors, including the chip thickness, substrate core thickness, EMC thickness, EMC Young’s modulus, EMC coefficient of thermal expansion, EMC curing shrinkage, mold temperature, and transfer pressure. The evaluation results indicate that the material properties of EMC and mold temperature are the most critical parameters for warpage control of the IC package. This study demonstrates a digital twin for the encapsulating process and provides guidance for robust package design.