An electronic packaging technique using silicone-based conductive adhesives was applied to the fabrication of tactile sensor sheets using poly (vinylidene fluoride) (PVDF) films for artificial skin applications in robots and related equipment. Silicone-based conductive adhesives containing 85 wt % Ag particles were employed for wiring and interconnection. In addition, the sensor sheet was perfectly encapsulated by injection molding of the silicone rubber. Prototype tactile sensor sheets were connected to a self-organized network of distributed processors and shown to work successfully.

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A novel Bi-base solder for mounting semiconductor power devices on inverters used in hybrid and fuel-cell vehicles was studied. The solder consists of Bi-base matrix (m.p. (melting point) =270°C), which facilitates high-temperature soldering, and dispersion particles of a Cu-Al-Mn alloy, whose thermoelastic martensitic microstructure is expected to relax the thermal stress. The tensile strength of the developed solders was found to be remarkably improved compared with that of pure Bi. Results of tensile tests at elevated temperatures showed greater elongation and lower strength than those at room temperature. However, sufficient tensile strength was still remained at 195°C. Effects of the CTE (coefficient of thermal expansion) and the surface substance of chips and substrates on the IMC (intermetallic compound) formation and thermal cycling properties were investigated. Even after 1983 thermal cycles between -40°C and 200°C, neither intermetallic compounds nor cracks were observed at the Cu/Bi-base solder interfaces in the CTE matched samples.

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The new LTCC material has been developed by crystallization of glass compositions in the firing process so that the major amount of glass becomes cordierite. The new material has CTE (coefficient of thermal expansion) of 3.4E-6/degree Celsius and dielectric constant of 5.6. The CTE of the new LTCC material is very close to that of silicon, which realizes high mounting reliability of a silicon device. We have measured the maximum principal stress in a silicon device mounted on test packages, using a piezoelectric element built-in the device. In the case of our new LTCC package, the stress in the device was around 0 Mp, while a Build-Up package (CTE: 17.0 E-6/degree Celsius) has shown the stress about 80 MPa. Our new LTCC material can be co-fired with copper conductor, which realized high effective conductivity and low transmission loss. The new LTCC material has been confirmed to be a promising solution of packages for Low-k and Ultra Low-k devices.

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Achieving the high performance required today from electronic devices such as cellular phones and personal computers requires greatly increased signal processing speed. This means that a substrate material with excellent electrical properties also is required. One such material is liquid crystalline polymer (LCP) . Generally, a high alkaline solution and a dry process are used to pre-treat the LCP, to form a conductive layer. However, this pre-treatment does not create good adhesion strength. In this study, we attempted to form a conductive layer with good adhesion strength by employing a surface modification technique that used UV irradiation. The results showed that an adhesion strength of about 0.8kN⋅m^-1 can be achieved under optimum conditions. The surface roughness after surface modification was about 0.08μm in Rz. This surface was very smooth, compared with that produced by the conventional method.

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