Study of warpage due to P-V-T-C relation of EMC in IC packaging

There were many studies about the prediction of warpage due to thermal mismatch [1], [2]. However, cure induced warpage is usually ignored and the results can be inaccurate. To minimize this problem, a thorough understanding of epoxy molding compound with pressure-volume-temperature-cure (P-V-T-C) relation is necessary. This paper used the P-V-T-C relation of an encapsulation material to formulate the stress-strain relationship. With the help of finite element method and mold flow analysis, warpage predictions combined with P-V-T-C relation were performed and the results show that this approach is practical. For a given P-V-T-C relation, the shrinkage direction is pointing toward the gate and maximum warpage usually occurs at the boundary of an integrated circuit package. Variation of specific volume difference along the flow direction is larger than that perpendicular to the flow direction. When temperature difference is small in thickness direction, specific volume difference in thickness direction varies only slightly.