Junichi Katagiri

Fabrication of thin-film multilayer substrate using copper clad polyimide sheets

A novel fabrication process is proposed for thin film multilayer substrates. The feature of the process involves the lamination of polyimide sheets with previously inspected wiring patterns. Several technical points were investigated during development of the process. Fairly large dimensional changes occur in the polyimide sheets in the copper etching and lamination steps. However, these changes can be restrained by fixing the sheets to rigid frames. Excimer laser ablation is a useful method to form blind via holes with a high aspect ratio. These holes can be metallized successfully by electroless copper plating. >

Characterization of brominated poly(4-hydroxystyrene) derivatives containing unsaturated groups

Abstract Brominated poly(4-hydroxystyrene) (HS) derivatives containing unsaturated groups such as alkenyl or alkenoyl were investigated with infrared and 1H nuclear magnetic resonance spectroscopy. HS derivatives have good thermal properties and their decomposition temperatures were higher than 300°C. Their thermal degradation behaviour is interpreted by the strength of electron withdrawal of substituent groups. The dielectric constants of HS derivatives can be predicted by the Clausius-Mosotti equation. The calculated values are found to agree with the observed values. The dielectric constants of the polymer can be reduced by replacing hydroxy groups with alkenoyl groups, especially methacryloyl units.

Application of optical diagnosis to aged low-voltage cable insulation in nuclear plants

We have developed a novel non-destructive optical diagnosis technique for low-voltage cable insulations used in nuclear power plants. The key features of this diagnosis are the use of two wavelengths to measure the change in reflective absorbance (/spl Delta/A/sub R/), and the use of polarized light to measure crystallinity. Then, chemical kinetics is used to predict the lifetimes of the cable insulations. When cable insulations darken and harden with age, the /spl Delta/A/sub R/ and depolarization parameters increase. This means that the cross-linking density in the cable insulations increases due to deterioration reactions. When the cross-linking density of an insulation increases, its elasticity, corresponding to the materials life, increases. Similarly, as the crystallinity increases due to the change in the high-order structure of the insulating resin caused by irradiation, its elongation property decreases. The elongation property of insulation is one of the most important parameters that can be used to evaluate material lifetimes, because it relates to elasticity. The /spl Delta/A/sub R/ correlated with the elongation property, and the correlation coefficient of an accelerated experiment using model pieces was over 0.8. Thus, we concluded that this optical diagnosis could be applied to evaluate the degradation of cable insulations used in nuclear power plants.