Fabrication of a microlens array electroformed mold with low roughness and high hardness

Abstract

A systematic approach to achieve a LRHH (low roughness and high hardness) electroforming process is developed in this study. Because electroformed molds with low roughness and high hardness are required for microlens array fabrication using the LIGA-like process, the invented Ni–Co alloy-pressurized electroforming process is used to fabricate a metallic micro-mold for microlens array molding. The electrolyte parameters such as Co content, current density, brightener content, pH value and temperature will be examined with respect to roughness and hardness. An artificial neural network (ANN) is used to construct a system model that accurately predicts the responses for arbitrary parameter settings. A genetic algorithm (GA) is applied to minimize the surface roughness and improve the micro-mold hardness. The results show that the micro-mold surface roughness and hardness could be significantly improved using the ANN/GA approach. A LRHH electroforming process is carried out using parameter design to improve the surface morphology and increase the service life of the micro-mold during the forming process.