Warpage Estimation of Panel-Level Package from Panel to Strip by Using Multi-Scaling Sub-modeling Technique

The portable devices have involved the human life for decades. The high input/output (I/O) counts, and high frequency has been essential demands for the packaging of devices. The novel panel-level fan-out package (FO-PLP) is the solution for the higher demands. The warpage is always a difficult issue for the large area and thin film structure during the manufacturing process. The finite element analysis (FEA) is regarded as an efficient method to estimate the warpage. The difficulties of FEA for FO-PLP is the size changing from panel to strip. The warpage will change tremendously with different size of manufacturing process with a non-continues stress transmission. This research proposed a FEA with multiple point constraint (MPC) method for warpage estimation from panel to strip for FO-PLP. The chemical shrinkage of epoxy material is considered. The FE model is divided into multiple regions based on the ratio of copper contents for FEA. The element is non-continuous on the edge between the panel and strip. The stress between panel and strip is transmit with the MPC method. The complicated fine RDL, copper pillar, solder, and chip in packaging are modeling with equivalent layers to decrease the element numbers. The material test of FEA is utilized to obtain the material properties of equivalent layers, such as coefficient of thermal expansion, Young's modulus, shear modulus, and Poisson’ ratio. The reference temperature for equivalent layers are set with modified Timoshenko bimaterial approach in FEA. The estimated warpage of panel with complete RDL is 0.435 mm from FEA, which is close to the measured warpage of 0.419 mm from experiment. The variation between the simulation and experiment is 3.81 % only. Then the process of reflow, molding and carrier removing are finished on the separated strip. The warpage of strip from simulation and experiment are -2.847 mm and -2.76 mm, respectively. The variation of 3.15 % between the simulation and experiment prove the proposed method can predict the warpage behavior of the FO-PLP.