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.
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.
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.