An integrated process modeling methodology and module for sequential multi-layered substrate fabrication using a coupled cure-thermal-stress analysis approach

An integrated process modeling methodology using a coupled cure-thermal-stress analysis approach has been developed to determine the evolution of warpage and stresses during the sequential fabrication of high-density electronic packaging structure´s. The process modeling methodology has been demonstrated, for example, with a bi-layer structure consisting of a 3 mil (76.2 μm) thick Vialux 81^TM photodefinable dry film (PDDF) polymer on a Silicon substrate. Extensive material characterization of the thermomechanical properties of the thin film polymer is presented, including the development of a viscoelastic material model. The predicted warpage values have been validated with Shadow Moire experiments, while the predicted stress values have been validated with experimental data from the Flexus Thin Film Stress Measurement Apparatus. Good agreement is seen between the predicted and the experimental warpage and stress values during the entire cure process cycle. Finally, the importance of incorporating viscoelastic polymer behavior and processing history is emphasized in the context of developing the multi-layered HDI fabrication process