Research On Process In Injection Molding Of Microstructures In Optical Components

Micro-injection molding is a technology which refers to produce components or micro-structures with a feature size (at least in two dimensions) at a sub-millimeter by injection. With the rapid development of micro-optical devices, micro-medical instruments and micro-sensors, the micro-devices, as the major components of these devices, become the focus of the research and development. The forming quality of the micro-structures is the key factor to achieve their functions. Micro-structures with high quality can t be manufactured by the conventional injection molding method. As a result, it requires a study on the characteristics of the micro-injection molding process to find out the forming laws of processing parameters to manufacture the micro-structures, and then to determine the optimal processing conditions. This paper is divided into three parts to research the relations between the forming quality and processing parameters. The specific research work is listed as follows:1. The relations between the forming quality of an angle in micro-structures and processing parameters are studied on the V micro-groove at the bottom of a light guide plate (LGP) Based on a backlight module model (BLM), the parameters of the V micro-groove are optimized. Then the matching mold for LGP is designed and manufactured. The influences of process parameters on the selected index value are analyzed according to an orthogonal experiment. The precision of the angle and the depth is promoted for the part under the optimal processing parameters. A qualitative optical measurement indicates that the V micro-groove in the LGP changes the light to the requirement direction, and the luminance uniformity of the whole surface is better.2. The relations between the forming accuracy of dimensions (width and depth), the surface quality (roughness) of a micro-structure and processing parameters are researched on the trapezoidal micro-structure in the cladding layer of the optical waveguide. This paper, for the performance requirements of the trapezoidal micro-structure, analyzes the effect of processing parameters on the overall performance of the optical waveguide by an orthogonal experiment. Afterwards, a fuzzy weighted evaluation model is established for the optimization of multi-target problem to find out the best combination of process parameters, based on which an experiment is carried out. Finally, the result shows that the forming error of the dimension is reduced and the quality of the forming surface is improved for the part. The test on the performance of the optical waveguide indicates that the forming precision of the dimension and the quality of the forming surface meet the requirements.3. The relations between the replication fidelity of a micro-structure and processing parameters in injection molding are studied on a micro-lens array. The parameters of a micro-lens array are designed by the forming characters of a micro-lens array. According to the orthogonal experiment and a single factor test, the weight of products is selected as the evaluation indicator of the replication fidelity. The weight of the micro-lens array under different levels of processing parameters is analyzed and simulated by the software Autodesk Moldflow Insight 2010, and the optimal combination of processing parameters is determined. Based on the simulation result, an actual injection molding experiment is carried out. The test shows that the weight of the part increases, and the replication fidelity is promoted.4. The features of V micro-grooves, trapezoid micro-grooves and spherical micro-lens are summarized. Furthermore, the relationships of the mold filled in the injection molding process are analyzed, and the relations of forming quality among them are studied.