In this paper, an unbalanced dipole antenna with semicircular and trapezoidal radiators for UWB (Ultra Wideband) radio, formed on a PCB (Printed Circuit Board), is proposed. The radiator shape of dipole was investigated using the TLM (Transmission Line Modeling) method; the microstrip feedline integrated with the antenna was also investigated, so that the antenna could be built in mobile equipment. The resulting unbalanced dipole antenna consisting of semicircular and trapezoidal radiators operated in the widest frequency band, which was effectively excited by the microstrip feedline integrated with the antenna without deteriorating VSWR and directional characteristics. An experimental version of the antenna performed well. In conclusion, the unbalanced dipole antenna with semicircular and trapezoidal radiators proposed in this paper, operated well with VSWR≤2.0, directional gain from -3.8 to 5.0 dBi, and cross polarization ratio more than 15 dB, from 2.8 to 11.5 GHz (Bandwidth of 122%) .

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Low-temperature curing conductive ink, made from metal powder and resin binder, is used to print wiring on electronic circuit boards. Most commercially available conductive inks cannot be soldered. The goal of this study, therefore, was to develop a new conductive ink which can be soldered. We examined various kinds of metal powders, thermosetting resins, and unsaturated fatty acids to develop a low-temperature curing conductive ink that can be soldered. A specimen made from phenolic resin, silver-plating nickel powder, and oleic acid was found to be solderable. The electric conductivity of the specimen was about 2×10^-4 Ω⋅cm. The adhesive strength between the printed wiring conductive ink and lead-free solder was about 8.2 N/mm².

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We have proposed a supply current test method for detecting open leads in CMOS ICs. The method is based on the supply current of a circuit made of CMOS ICs, which flows when an AC electric field is supplied from outside the ICs. The electric field is generated by providing AC voltage between electrodes which are placed over the targeted leads and under a targeted PCB. In this paper, we experimentally examine how large an amplitude of AC voltage should be provided between the electrodes to detect open leads in the CPLD LSIs of PLCC, QFP and TQFP packages. The results reveal that the amplitude of the AC voltage needed to enable open leads detection depends on the shape of the package and the logic threshold voltage of the targeted ICs and printed circuit boards used. Also, they show that in some LSIs the required amplitude depends on the output logic level to an open lead.

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Recently, low dielectric material has been commonly used as printed circuit board material, to improve the performance and efficiency of electronic equipment. PTFE (Polytetrafluoroethylene) is one of the candidates for such Low-k material. Conventionally, a complicated etched surface has to be created by a strong etching media in order to achieve a good adhesion between the deposited metal and substrate. However, this complicated etched surface becomes a problem due to transmission loss through the skin effect. We therefore looked at a Cycloolefin Polymer (COP) that has an electric characteristic equal to PTFE. Return-to-zero (Rz) obtained a reformed surface with a low degree of roughness (about 1.0μm) by irradiating the COP with ultraviolet light for 10 minutes. With the use of a hypophosphorous acid type bath for electroless Cu plating, peel strength was 0.8 kNm^-1. A circuit with a comb type pattern was formed by a subtractive process. An initial insulation resistance was measured on the comb type pattern (the width of the circuit and the interval of pattern were 50 μm) with 100V impressed voltage and was shown to have a high enough value (1.7×10¹³Ω)

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