Study on Micro Fabrication of Mold Insert for Microlens Arrays by Micro Dispensing

Abstract

This work used micro dispensing technology to fabricate the master of microlens array, then uses electroforming technology to replication the Ni mold insert of microlens array and finally used micro hot embossing to replicate the plastic microlens array. This work used the Si10 resin by AutoStrade Company for dispensing material. The resin material was exposed to 80W halogen light. The resin will be hardened and become convex by surface tension effect on exposition. It can be used as the master of microlens array. This work sputtered a silver layer of 150 nm thick on the master for conducting electricity layer. The electroforming technology replicateed on the Ni mold insert from the master of microlens array. Finally, the micro hot embossing technology was used to replicate the molded microlens array. The molding experiment used PMMA and PC optical film. The experiment studied the influence of processing parameters of hot embossing by processing temperature, embossing pressure, embossing time and de-molding temperature. This work used the Taguchi’s Method to search the best processing parameter for molded microlens array. This work used the microscope, surface profiler and SEM to measure the surface profile of master, mold insert and molded microlens array. This work also used AFM to measure the surface roughness of master, mold insert and molded microlens array. In addition, this work measured the optical strength and the focal length to discuss optical characteristics of molded microlens array.