Laser micromachining of mold inserts for replication techniques: state of the art and applications

The rapid fabrication of microcomponents made from polymers will be presented. The whole fabrication process is divided into three main steps: First, direct patterning of polymers with excimer laser radiation enables the fabrication of first prototypes. Second, laser assisted micromachining using Nd:YAG and KrF-Excimer laser allows a rapid manufacturing of microstructured mold inserts. Third, the application of light induced reaction injection molding (UV-RIM) gives the access to the replication of the previously fabricated mold insert. The fabrication of prototypes made of polymer is carried out highly precisely with excimer laser radiation. With the aid of a motorised aperture mask, CAD data are transmitted directly into the polymeric surface. With an appropriate pretreatment of the polymer surface the debris formation can be drastically reduced. A promising method of micropatterning of mold inserts made of steel is called laser microcaving. This processing technique enables a clean patterning process with only a small amount of debris and melt. The etch rate and surface quality strongly depend on the chemical composition of the steel and the process parameters. Surface qualities with a roughness of about 300 nm can be achieved. Microstructures composed of polymers or ceramic-composites are successfully demolded by using the UV-RIM technique with aspect ratios up to 10. Capillary Electrophoresis-Chips made of PMMA are fabricated, and the functionality of the CE-Chips is demonstrated.