This investigation explores the microinjection molding of light-guided plates (LGPs) using lithography, electroplating, and molding (LIGA)-like fabricated stampers. The 3.5-in. LGP has a thin wall (0.76 mm) and micron-sized features of truncated pyramidal prisms (70 mu m wide and 38.3 mu m deep, with a vertex angle of 70.5 degrees) and v-grooves (9.8 mu m deep). Stampers for LGP injection molding (IM) are fabricated precisely by combining the anisotropic wet etching of silicon-on-insulation wafers with electroforming. LGPs must have multiple quality characteristics, such as good replication effects on microfeatures and flatness of the plate. In this study, the Taguchi method and gray relational analysis are adopted to optimize the microinjection molding parameters. Various IM parameters, including mold temperature, melt temperature, holding pressure, and injection speed, are considered. Experimental results demonstrate that mold temperature and holding pressure dominate the performance. Gray relational analysis and the Taguchi method can be used to determine the optimal process parameters for LGP molding. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3446-3455, 2011