A novel integrated warpage prediction model based on characterization of viscoelasticity in time domain and chemical shrinkage for molded underfill

In order to efficiently optimize the structure and process of thin packages, it is crucial to accurately predict the warpage of thin packages during in-molding and post-mold curing (PMC) processes. In this paper, we describe an integrated modeling approach, which takes both viscoelastic and chemical shrinkage behaviors into account for molded underfill process. The time-domain viscoelastic properties and chemical shrinkage of molded underfill are included in the finite-element (FE) model. The simulation results are in good agreement with the measured 3D warpage contour and values by Shadow Moiré method. In contrast, the simulated constitutive behavior of molded underfill with only temperature-dependent elastic property exhibits poor agreement with the experimental results.