Warpage simulation and optimization of panel level fan-out package in post molding cure

Nowadays, the panel level fan-out packaging is gradually entering the advanced packaging market owning to the advantages of low cost, high cost performance and high throughput. Due to the mismatch of coefficient of thermal expansion(CTE) between the various packaging materials and the cure shrinkage of Epoxy Molding Compound (EMC), Warpage and cracking are observed and became main problems in further applications of fan-out packaging. In this article an equal-ratio reduction model in the form of "EMC-chip-temporary bonding layer-carrier" is established to understand the correlation between warpage and stress in panel level fan-out package. The finite element method(FEM) is used to study the influences of the packaging structure (including the thickness of each material and packaging ratio) , packaging process and material properties(Young's modulus and CTE) on warpage and stress. Based on the simulation results, it is found that the thickness of the chip, EMC and carrier has a strong influence on the packaging warpage distribution compared to the Young's modulus of EMC. During the post-curing stage from 175°C to 25°C, the chip thickness increased from 0.1mm to 0.3mm, and the warpage value decreased by about 15.6%. When the EMC thickness increased from 0.2mm to 0.4mm, the warping value increased by 10.3%. When the carrier thickness increased from 0.4mm to 0.8mm, the warping value decreased by about 43.3%. Increasing the packaging ratio can also effectively reduce the warpage value. The results are in effective range of (in according with) general experimental observation. The methods of this study can provide an approach to predict, control and design the warping behavior of fan-out packaging based on packaging material and structure.