Human body communication is expected to be a viable new transmission method for networks between wearable devices working together in a body area network (BAN). Wearable devices demand long battery life, small size, and light weight. Therefore, it is important to investigate the input impedance characteristics of the electrodes and design the electrode structure in such a way as to improve the communication qualities. The characteristics of the human body are important for designing the antennas (electrodes) used for close range communication in a human body communication system. Normally, homogenous muscle phantoms are used for measuring the input impedance characteristics of these antennas. However, nobody has measured the input impedance characteristics of electrodes for human body communication at a frequency of 10 MHz using phantoms that take into account the actual tissue structure of the human body. Therefore, it is necessary to measure the impedance characteristics using phantoms which consider skin, fat, and muscle. In this study, changes in the input impedance characteristics were analyzed considering the electrical properties of a phantom containing muscle and fat. Moreover we tried to develop a human muscle and fat phantom for human body communication system available at a frequency of 10 MHz.

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With the sophistication and miniaturization of electronic devices, printed wiring boards are progressing to ever higher densities. In the field of solder resist (SR), the miniaturization of the wiring with higher density, there is an increasing demand to improve thermal shock resistance. In an effort to increase thermal shock durability, we have devised a design that reduces the mobility of the polymer terminal of the cured film. A SR which contains a polyurethane binder having terminal carboxyl groups has been found to improve the thermal shock durability.

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With the sophistication and miniaturization of electronic devices, printed wiring boards are progressing to ever-higher densities. In the field of solder resist (SR), the miniaturization of the wiring with higher density has led to an increasing demand to improve reliability (thermal shock resistance and insulation reliability). We have shown that it is effective to increase γ-relaxation, which is an index of the stress relaxation at low temperatures, in order to improve both the thermal shock resistance and insulation reliability of the solder resist.

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