An Improved Mold Flow Optimization Technology for High-Density Power Modules

During the plastic packaging process, voids and weld lines are common problems. As the volume of Power Modules is becoming smaller and thinner, more and more attention has been paid to solve the void defects. Power Modules have complex structures and dense components, which may cause void risks. In this article, an improved 3D mold flow technology for High-Density Power Modules package is conducted to predict the location of the voids generation and the number of weld lines throughout the plastic encapsulation process, which is mainly about to find the best optimization to reduce the risk of voids through the two parts. The first part is including three aspects which are gate locations, viscosity property of materials, and segment injection. According to the simulation verification, the results show that the best gate location and a reasonable range of viscosity properties for the material can effectively decrease the voids risk. In addition, segment injection has more advantages than uniform injection in terms of reducing voids risks When the melt flows through the top of the highest component of Power Module package. The second part is the verification of DoEs (Design of Experiments) that show the influence of the solder ball size and ball to substrate area ratio on the number of weld lines by comparing different kinds of experiments. The results show that the smaller the balls size, and the pitch is not sufficiently large, the greater the number of weld lines. Therefore, through the comparison of the above experimental data, it is very necessary to find an optimal scheme to reduce production defects during the molding process of the products, and greatly improve the reliability of the product.