Mold Flow Analysis and Optimization in Injection Molding Process for Semiconductor Packages

Abstract

Molding process of packages is the key link in IC packages and test. Epoxy resin is melted to fill into a specific mold to coat the chip. Filling the cavity with dissatisfaction will lead to crack or popcorn when SMT (Surface Mounted Technology) etc. The wire sweep will lead to the failure of the circuit crack and affect the reliability of the product. Due to epoxy molding fluidity, structural deformation during melting, there are complex interactions between the polymerization reactions of the package molding.The design of the fixture adopts is used by the traditional trial and error method, consistency in the filling process is judged by the half mold test. Wire sweep, crystal core offset and delamination are judged by X-ray. The formula of grease, the design parameters of the gate and exhaust slot of the mold, and so on can be optimized in the actual production situation. A lot of energy, time and money are wasted by the post validation method, at last it may even fail. Through the numerical simulation analysis of mold flow with simulation software, the Spiral flow of EMC ( Epoxy Molding Compound) is considered, filling property of epoxy resin and wire sweep are analyzed and the parameters can be optimized. To take the minimum wire sweep and filling no cavity as the optimal goal, the experimental design of materials, process parameters and gate direction can be obtained, the significant factor ranking of influencing factors can be concluded with DOE (Design Of Experiments), and the reasonable life cycle of injection molding production can be effectively controlled. The qualified rate of products can be improved, the mold development cycle can be shortened and the number of mold trials can be reduced.