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Alternator, which supplies electric energy to a battery and electrical loads when it is rotated by engine via belt, is one of key components to improve vehicle fuel efficiency. We have reduced rectification loss from AC to DC with a MOSFET instead of a rectifier diode. It is important to turn on the MOSFET and off during a rectification period, called synchronous control, to avoid a current flow in the reverse direction from the battery. We turn it off so as to remain a certain conduction period through a body diode of the MOSFET before the rectification end. It is controlled by making a feedback process to coincide with an internal target conduction period based on the rotational speed of the alternator. We reduced a voltage surge risk at turn-off by changing the feedback gain depending on the sign of the time difference between the measured period and the target.

PBT (polybutylene terephthalate) and epoxy adhesive, which both have superior heat resistance and environmental resistance, are a representative combination now being applied to many parts. Generally, PBT is annealed after molding at a temperature above the glass transition temperature to ensure dimensional stability when in use. But in this case, this process decreases the adhesive strength between PBT and epoxy. This study analyzes the adhesion degradation mechanism in this system and a countermeasure technology is proposed. Regarding this PBT-epoxy adhesion degradation mechanism, focus is placed on changes in the fracture surface, which is analyzed before and after annealing. From this analysis it becomes clear that generation of a WBL (weak boundary layer) is caused by non-crystallization and a migration of the PBT functional group on the adhesion surface layer.

Measurements of residual stress in a printed circuit board, which consists of copper foil, silver alloy and thermo plastic resin, were conducted under a thermal cycle. The printed circuit board was given a ten-layer repeat of prepreg and made by thermocompression bonding. Experiments suggested the possibility of measuring surface residual stress of copper circuits and the internal residual stress of metallic connections by synchrotron radiation of Spring-8. FEM analysis of the printed circuit board during a thermal cycle was conducted, and the result was adjusted to X-ray stress using absorption correction. X-ray stress during a heat-cycle obtained by synchrotron radiation showed good agreement with stress calculated by FEM analysis.