In addition to low-dielectric-constant materials and skin effects of routing patterns, a routing technique that minimizes electromagnetic noise is essential to increase transmission speeds. Therefore, we need to consider reducing transmission losses caused by reflection and cross talk that results from the placement of through holes and traces closed to them as well as via structures on the core layer used in CPU packaging substrates. This paper uses a simulation method to confirm the influence on transmission losses of structures that consist of signal vias and traces closed to them in the routing design of high-signal-transmission PCBs.

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With non-destructive, simple, and low-priced testing methods (which can be applied to manufacturing processes), we can assure high quality production by applying inspection across all products. Quality assurance in wire bonding is possible by using state diagnosis which utilizes detection of elastic waves close to the bonded joint. We succeeded in detecting elastic waves under difficult conditions and in harsh environments by using a thin AE (Acoustic Emission) sensor developed using AlN piezoelectric thin film technology. We attempted to conduct a wire bonding state estimation using the MT (Mahalanobis-Taguchi) method which is a simple and powerful pattern recognition technique. Two issues are raised when applying this method to the manufacturing process: 1) a large probability bias caused by an insufficient number of data samples, and 2) securing homogeneity of the Unit Space. In this paper, we present a state diagnosis method utilizing a real-world application which uses piezoelectric thin film sensing and an improved MT method to which ensemble learning is applied. Performance of this proposed method is also examined through a common benchmark dataset to assure efficient operation in any manufacturing process.

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An electro-thermal simulation for a microwave gallium nitride (GaN) field-effect transistor (FET) high-speed-switching power-supply was carried out to precisely estimate the influence of the self-heating effect on high-power operation. In this simulation, significant differences in the output power, power efficiency, and operation temperature of the FET were confirmed in comparison with calculated results for a simplified ideal model, when the switching frequency was changed from 10 MHz to several GHz, especially at the higher frequency range. For pulse-width modulation switching, the maximum variation of the operation temperature according to the output voltage variation was obtained at a center frequency of 2.5 MHz, which was about 44% of the relative temperature variation relative to the average temperature increase.

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This paper reports on the results of a real-time measurement of a copper-oxide reduction process using formic acid. For the observation, an experiment system combining an ellipsometer and vacuum chamber was constructed. Measurements were performed for both native oxide and thermal oxide, and activation energy values were calculated from the temperature dependence of the reduction rates. Activation energy values of 61.9 kJ/mol and 100.6 kJ/mol were obtained for the native oxide and the thermal oxide, respectively. In addition, it was confirmed that Cu₂O is formed in both oxides with different distributions in the depth direction. From the results, it is expected that the difference in activation energy can be attributed to the difference in energy of oxygen diffusing from the depths of the substrate to its surface.

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For smart textiles applications, textile compatible power supplies have been highly anticipated to ensure autonomous operation. Inspired by textile technologies, we have successfully prototyped an energy harvesting yarn with a spherical solar cell array arranged in parallel.

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