Electric appliances utilize various toxic metal elements in their parts. For instance, solder containing lead (Pb) adheres to printed circuit boards, and antimony (Sb) remains in various electronic parts. After electric appliances have been used, they have been almost thrown away as waste in the dumping ground with no management for the recovering or for the recycling. Elution of a large extent of Pb may be caused by waste electric appliances under acidic rain for a long period. The waste management of electric appliances has been studied at various situations, but the practical system for the waste management has not been built up et. In this study, the removal of solder adhering to printed circuit boards was investigated by means of vibrating them under appropriate temperature, and solder more than 60% was removed from them. The elution of Pb in printed circuit boards before and after the removal of solder from them was also investigated under condition of nitric acid solution of pH3. The elution concentration of Pb from printed circuit boards was smaller after than before the treatment above mentioned. As for the pre-treatment of waste electric appliances, it is desirable to establish the recovering or the recycling management system of them.

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Low loss optical waveguides having a 45°reflector are key of optical surface mount technology (O-SMT) which was proposed to provide a possible solution to growing serious problems in manufacturing process of opto-electronic products. We used polymeric optical waveguides for the substrate of 0-SMT. The material of core was polymethyl-methacrylate (PMMA), and the core size was 40×40μm², the Δ=1.2% multimode waveguide. The waveguides with a 45°mirror were fabricated by cutting the waveguides with a 90°V-shaped diamond saw. The insertion loss of the waveguide with 45°mirror was mesured to be 1.5dB, thus the mirror loss was estimated 1.1dB at the waveguide length 50mm and the propagation loss 0.08dB/cm. Furthermore the cause of loss is investigated by Ray Tracing Method.

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Electronics products are becoming smaller these days. Thus the technology to connect fine pitch electrodes are very important. We developed the new soldering method for connecting FPC (flexible printed circuit) and display device without applying any flux which deteriorates the insulation property between electrodes. In the ordinary soldering method, flux was used to dissolve the oxide film which interfere the soldering process. In new method, we have introduced alkane to remove oxide film by physical reaction not by chemical reaction. When heat is applied and alkane is boiled, volume expansion energy breaks the oxide film and desirable clean solder surface is obtained. As a result, the connecting are become as much as the ordinary method does.

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It is necessary to determine the solderability of the Printed Wiring Boards (PWB) quantitatively before mounting and assembly, in order to ensure the soldering reliability of the finished product. There was no Quantitative Test Method for the evaluation of the Solderability of Printed Wiring Boards in the world. We established this method by using the Reflow Soldering Tester (SS-ST) which was developed by our division. This result suggest that we can apply to the acceptance test for Printed Wiring Boards and the analysis of poor soldering causes. And then we can have a common measure through all soldering process, including the solder paste and the surface mounted components.

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Generally, Tin-doped indium oxide (ITO) has been used as a transparent conductive films for the flat panel display (FPD) . The resistance of ITO, however, must be decreased along with the expansion of a screen size of a display. One of the attractive methods to increase the conductivity without decreasing transmittance is the electroless nickel plating at the fringe of the ITO patterns. Selective metallized films at the fringe areas of the ITO films can be formed by dipping to a diluted PdCl₂ solution as an initiator of electroless nickel plating on ITO. Furthermore, the addition of tartaric ions to the diluted PdC1₂ solution as an catalyst with accelerate the selectivity, because Pd ions form a complex with tartaric ions, which decreases Pd adsorption amounts on ITO.

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A film formation technology using the dispersed ultra fine particle paste will be introduced. The particles under 100 am in diameter are defined as ultra fine particles (UFPs) . The melting temperatures of UFPs are extensively lower than the bulk materials, thus the dispersed UFP paste can be sintered at lower than 300°C. A film formed using the dispersed UFP paste is dense and has smooth surface because each particle is individually separated and suspend in an organic solvent without aggregations. The particles have high purity because formed in a pure inert gas atmosphere by the gas evaporation method. Several metal additives have been added to this dispersed UFP paste for improve the adhesion strength against several kinds of substrate such as glass, alumina or polyimide films. The viscosity can be controlled from 85 to 20000 cps. The direct drawing system by a micro-dispenser using this viscosity controlled paste had been developed. It can draw a line down to 40μm in width and a spot down to 30μm in diameter.

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