A Quantitative Model to Understand the Effect of Gravity on the Warpage of Fan-Out Panel-Level Packaging

In this article, a universal and concise theoretical model is proposed to quantify the effect of gravity on packaging warpage by considering the competition between the thermal and chemical shrinkage of packaging materials and the flexural stiffness of packaging structures. Experimental study and finite element simulation for the warpage distributions of two fan-out panel-level packaging structures with sizes of 310 mm
$\times320$
mm are carried out to verify the effectiveness of the proposed model. Under the ideal gravity-free condition, the warpage is proportional to the square of the packaging structure size. Under the gravity effect, the warpage follows a brief quartic expression of the packaging structure size. The gravity can reduce the bending moment in the structure and thereby lead to the decrease of the total warpage. For larger-size structures, the effect of gravity on warpage is more pronounced. It is found that the predictions by the model fit well with both experimental and simulation results. The theoretical model in our work can provide an effective tool to predict the warpage with consideration of the gravity effect and will promote further development and design of large-scale packaging structures.