Post-Buckling Analysis for Addressing Asymmetric Warping of Fan-Out Reconstitution Process

Fan-out reconstitution process involves numerous thermal cycling and significant wafer warping would inevitable occur and full scale simulations are thus usually required for properly optimizing design and process parameters. However, the present nonlinear finite element approach of predicting wafer asymmetric warpage could result in extra computational cost and alternative approach might be worth to explore for performing efficient simulations. Thus, this work proposes a buckling/post-buckling scheme as a potential alternative for studying wafer warping problem and applies the schemes in real packaging process for demonstrating the feasibility and potentials of the approach. The simulation shows that the errors of bifurcation temperature and warpage of the two analyses are 14% and 6%, respectively w.r.t. nonlinear simulation thus the deviations are within acceptable range. Subsequently, process emulator with buckling/post-buckling analysis is established to predict warpage in the large deformation region. And compare with the nonlinear analysis, the error of warpage is within 3%. In the future, more numerical models are discussed to analyze the sensitivity of parameters thus the deformation behavior of actual process can be described more realistically.