Fabrication of wafer-level double-sided microlens array using injection compression molding

Double-sided microlens arrays (MLAs) are the key optical components of the optical component. To enhance microlens fabrication productivity, a wafer-level, double-sided MLA was designed and fabricated using injection compression molding (ICM). First, the Moldex3D simulation analysis results show that the design of the disc mold saves material and representation time than the multi-cavity mold. The 4-inch disc mold with a 4 × 4 double-sided MLA of two inserts was used to do the study. The L9 orthogonal Taguchi method was employed to find the best combination of molding parameters. For molding experiments, 2 mold inserts with 4 × 4 convex and concave lens arrays were machined by the ultraprecision diamond turning. They were mounted into molds in one of two locations, either close to the gate or far from the gate. The molding experiment results confirmed that the ICM-molded MLA was better than the injection molding (IM)-molded one, with higher precision and lower residual stress. The results were similar to the simulations. The ICM molded MLA has a focal length of 2.549 mm and a spot size of 50 μm and the total deviation percentage is less than 1%. This study proves the feasibility of fabricating a wafer-level, double-sided MLA disc using ICM.