Hot embossing is the technique to fabricate high precision and high quality plastic microstructures. Industrial fabrication of plastics components is normally achieved by injection molding. Hot embossing is actually used only for a few optical applications where high precision and high quality are important.The advantages of hot embossing are low material flow, avoiding internal stress which induces e.g. scattering centers infavorable for optical applications, and low flow rates, so more delicate structures can be fabricated, such as free standing thin columns or narrow oblong walls.The development of modular molding equipment, orientated on industrial standards has opened the door to the fabrication of plastic microcomponents in great numbers (for example LIGA-UV/VIS-spectrometers). Hot embossing has the potential of increasing production rates and therefore decreasing production costs by the enlargement of the molding surface and automatization of the molding process.

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.

In microsystem technology a large range of different materials will be available only after the necessary micromanufacturing techniques have been developed or adapted. Existing manufacturing techniques are structuring or shaping techniques producing three-dimensional microstructures out of silicon (silicon etching, silicon surface micromechanics), mostly unfilled plastics (lithographic techniques, injection molding, hot embossing, reaction molding) or a few pure metals or binary alloys (electroforming).The choice of materials for microcomponents is determined by the function and conditions of use of microsystems. Especially the range of metals is still restricted considerably because the only processes available are electroforming and thin-layer techniques.It is for these reasons that we are developing various processes for manufacturing three-dimensional metal microstructures. In addition to direct electroforming of injection molding lost plastic micromolds, these are a new microcasting process and Micro Metal Injection Molding (Micro MIM). Microstructures have already been molded from mold inserts made by micromechanical cutting or by the LIGA technique. The results achieved, and future prospects, are outlined below.

The fabrication and the design of a new ®ber connector for up to 16 single-or multimode ®bers are presented. The connector features the following essential advantages: low cost fabrication by micro injection molding, easy assembly due to elastic alignment structures made possible using LIGA technology and bonding by UVcuring adhesive, and a hermaphroditic connector design in order to avoid damage of the precision part of the ferrule. The mean insertion loss is 0.35 dB with multimode ®bers and as it turned out from ®rst experiments 1.16 dB with singlemode ®bers.

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