Micro injection molding is presently on its way to become an established manufacturing process in commercialising Microsystem Technologies. Enhanced products from plastics for micro optical or medical applications are entering the market. New developments like the different kinds of injection molding for microstructured components from plastics, metals or ceramics will increase the material range available in microdimensions. This will open up opportunities for increasing economic ef®ciency, for new ®elds of applications as well as for innovative products in the future.

We are gratefully acknowledged to the Stifterverband Metalle and the Deutsche Forschungsgemeinschaft for financial support. Additionally we wish to thank the BASF AG, Hu¨ls AG, Hoechst AG and Degussa AG for delivering materials and the Ciba Additive GmbH for the kind donation of the photoinitiators. We also wish to thank our colleagues, especially Mr. P. Holzer and the members of the galvanic team of the corrosion division of our institute (IMFIII/KOR) and microparts GmbH for the electroplating and helpful support.Abstract Injection molding technology and its different modifications represent established processes for manufacturing polymer products with high accuracy in large scale production. Enhanced machine and tool technologies like evacuation units and special temperization systems have already been adapted to the molding of microstructures with high aspect ratios. Cycle times are actually in the range of minutes and depend on the geometry of the microstructures and the materials used. Based on injection molding of lost plastic microforms new processes for the manufacturing of ceramic or metal microstructures are being developed.

Originally developed for the replication of high aspect ratio LIGA structures, micro injection molding is presently on its way to become an established manufacturing process. Enhanced technological products like micro optical devices are entering the market. New developments like the different kinds of injection molding with several components open up opportunities for increasing economic efficiency as well as for new fields of applications. Software tools for the simulation of the thermal household of the molding tool and/or the moldfilling process itself can provide useful but not wholly sufficient assistance for the optimization of micro injection molding.

Starting from commercially‐available, polymer‐based reactive resins like acrylates or unsaturated polyesters, a systematic investigation was carried out as to the influence organic dopants like phenanthrene and its derivatives have on the optical and thermal properties of the mixtures resulting from curing to the final thermoplastic polymer. The refractive index of PMMA at 633 nm can be increased, starting from 1.49 for the pure polymer, up to a value of around 1.55, and, in the case of the polyester, from 1.565 up to 1.6. The transmittance in the visible range is slightly affected at a lower dopant concentration of up to 10 wt.‐%, and remains better than 80% for a sample with a thickness of 1 mm, in the range between 500 and 800 nm. An unwanted side‐effect of larger dopant concentrations is to lower the glass transition temperature significantly.magnified image