We propose a new electrostatically-actuated micromirror array. Using solder flip chip bonding technology, the desired electrode gap and the mirror rotation range can be easily created and enlarged. The use of solder assembly technology also provides us not only design flexibility but also precise gap height and mirror position control. In the mirror assembly process, a new MEMS transfer method using temporary fuse-away tethers is used to achieve robust and clean batch assembly. The mirror array is designed through FEM analysis and design optimization using a surface response method. The driving power of the optimized mirror system is reduced to one-third that of the initial design. The testing results of the fabricated mirror device show consistency with the predicted mirror performance and assembly precision.

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Composite films composed of various polyimides derived from decamethylene bis (trimellitate) anhydride (DBTA), an epoxy resin and a silver filler were prepared and their properties were studied. The films showed thermoplastic behavior before curing with molten performance at high temperatures above their Tgs, and thermosetting behavior after curing with restricted flow behavior even above their Tgs. The limited flow behavior results from the network structure formation in the film. The adhesion strength of the film when used as an adhesive film between two adherents having different thermal strains was affected by two main factors: the modulus and stress relaxation property of the film. In this paper, the relationship between the chemical structure of the polyimides and the various properties of the composite films is discussed.

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This study describes a micro connector produced using UV thick resist, lithography, and electroforming, and its evaluation. The fabricated connector has 100 pins with 80pm pitch. The terminals of the fabricated micro connector were 50μm thick and 15μm wide (minimum) . The maximum aspect ratio of the fabricated micro connector is 3.3 and the terminal pitch is 80μm. In evaluating its specific properties, contact force, contact resistance, Young's modulus and permissible current have been determined. The contact force is 3.3 mN at 5μm displacement of the socket terminal. The contact resistance among terminals is shown to be less than 50 mΩ using a four-point probe method. Young's modulus of he Ni structure is found to be 180 GPa using the SPM method. The designed connector treated by Au plating has indicated the possibility of obtaining stable electric contact after the durability test.

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ABS resin has been widely applied as a plating substrate on plastics in applications such as vehicles and electrical devices. Generally the ABS resin is etched by strong oxidizing agents including H₂SO₄and CrO₃for the improvement of adhesion strength between the deposited metal and the ABS resin. This etching method has been used in production for over 40 years. In recent years, environmental pollution control has become an important concern, as we can see in documents such as the EU Directive on Waste from Electrical and Electronic Equipment (WEEE) and Restriction on Hazardous Substances (RoHS) . Surface finishing technologies for corrosion protection in automobiles have become especially urgent matters for cutting down the hazardous substances. As per the EU Directive on the End of Life Vehicles (ELV), the use of hexavalent chromium on automobiles related parts will be forbidden in the European Union area after July, 2007. Accordingly, we are required to develop an alternative technology without using hazardous materials. We have focused on the application of titanium oxide (TiO₂), which is a photocatalyst, as an alternative to chromic acid, and have found chemical reforming on the ABS resin surface by UV light irradiation under the presence of TiO₂. We confirmed that reforming of the ABS substrate by this process improved the adhesion between electroless Ni-P plating film and ABS. Adhesion strength of about 1.0 kgf/cm between ABS and deposited metal was obtained under the optimum treatment condition.

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We have developed a solder joint material with a plastic core. In this paper, we report on the thermal conductivity of this material. We evaluated the thermal resistanceθ j-awith 352 pin EBGA and 352 pin PBGA, and also carried out a thermal conductivity analysis using computer simulation. The result show that the θj-aof the 352 pin EBGA was 12°C/W, and the θj-aof the 352 pin PBGA was 20°C/W. So this material is applicable to high frequency and power packages (CPU, MCM, MCP, stacked package and so on) .

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LSI suppliers have been making strong efforts to introduce LSI packages with lead free plating terminals. But, gull wing lead LSI packages still use Sn-Pb plating. Many papers report that the combination of Sn-Ag-Cu solder paste and Sn-Pb plating develops a low temperature layer on PWB copper pads and causes pad peel-off in the wave soldering process. This failure appears conspicuously in the case of low temperature solder alloys containing Bi such as Sn-Zn-Bi and Sn-Ag-In-Bi. This paper examines the composition of the low temperature layer and the peel-off limit temperature using an EPMA (Electron Probe Micro Analyzer), simulation software for the phase diagram, and an actual tensile test. As a result, the required control temperature for wave and selective soldering process is clarified.

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