Multi-physics coupled modeling of process-induced warpage in advanced fan-out wafer-level semiconductor packages

초록

Warpage evolution in advanced fan-out wafer-level packaging (FOWLP) was quantitatively analyzed through a multi-physics coupled framework integrating experimental characterization and finite element simulations. The thermo-chemo-mechanical behavior of the epoxy molding compound (EMC) was modeled by incorporating cure kinetics, viscoelasticity, and process-induced residual stresses. In-situ cure monitoring using fiber Bragg grating (FBG) and dielectric sensors revealed an effective cure shrinkage of 0.110%, with gelation occurring at 143 °C. Dynamic mechanical analysis provided viscoelastic parameters represented by the Prony series and Williams–Landel–Ferry (WLF) model. Grinding experiments systematically evaluated the influence of abrasive grit, spindle speed, contact pressure, and grinding depth on damaged layer characteristics. Post-mold curing prior to grinding reduced the damaged layer thickness from 14.8 μm to 10.1 μm but increased residual stress from 7.75 MPa to 14.51 MPa, amplifying warpage due to diminished viscoelastic relaxation. The process sequence of molding → post-mold curing → grinding achieved 8.1% lower final warpage compared to the conventional molding → grinding → post-mold curing route, surpassing the 3.7% variation from die thickness reduction (80 μm → 45 μm). The simulation framework predicted warpage evolution with <5.6% deviation from experiments, demonstrating that grinding-induced stress redistribution and relaxation during post-mold curing are dominant factors governing overall deformation. This multi-physics approach provides predictive and quantitative insights for process-chain optimization in FOWLP manufacturing.

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