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 efficiency, for new fields of applications as well as for innovative products in the future.
The fabrication and the design of a new fiber connector for up to 16 single- or multimode fibers is 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 UV-curing 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 fibers and as it turned out from first experiments 1.16 dB with singlemode fibers.
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.
A great variety of uses of microsystems opens up when sensors and actuators are supplemented by powerful electronics. In silicon technology, the monolithic integration of micromechanical and microelectronic components into one system is possible in a sequence of process steps, although only very few basic sensor and actuator principles can be put into effect. LIGA technology, with the latitude it offers with regard to lateral geometry at high aspect ratios, and its great variety of materials, allows many different sensor and actuator principles to be put into effect. However, integration with microelectronics circuits so far has been possible only in a hybrid way. The new process described in this paper is characterized by the separation of the molding process from the positioning and bonding processes. First, a microstructured polymer film is produced by hot embossing on an auxiliary substrate. Next this self-supporting polymer film is joined to the prestructured wafer by thermal bonding. In this way it is possible, irrespective of the size of the molding tool and the embossing conditions, to position microstructures on a variety of substrates, e.g. by the pick-and-place technique. Finally, the quality of the joint between substrate and microstructured polymer film is demonstrated by using the film as lost form for galvanoforming metallic microstructures on top of the wafer.
In microsystem technology a large range of different 6materials 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).
A technology for the fabrication of movable LIGA-Microstructures by molding was developed, which enables the cheaper production of e.g. LIGA-Acceleration Sensors [1]. For this purpose an aligned molding process had to be developed. The realized experimental setup consists of two subsystems, the molding machine and the alignment arrangement [2]. After aligning a substrate it is transported into the molding machine. An effective and extremely precise dimension translation system is required. Although during modling temperature changes appear and high forces are applied, the dimension stability during the molding process has to be guaranteed. The presented system and setup deals successfully with these conditions. An alignment quality of ± 10 μm is realized. Using the aligned molding technology temperature compensated LIGA-acceleration sensors [1] were fabricated. The proper function of the sensors was demonstrated.