Along with the recent remarkable development of the electronics industry, further miniaturization and higher performance of electronic devices are anticipated. Reaching these objectives necessitates the miniaturization of built-in parts. Miniaturizing one such component, printed circuit boards（PCBs）, the base on which electronic components are mounted, requires increased density. A mainstream manufacturing method, semi-additive method, enables fine wiring formation with plating and etching technologies to facilitate miniaturization and to enhance the reliability of PCB manufacturing and related component-mounting technologies. For this study, we measured AC impedance associated with etching processes using a formic acid type roughening solution under various conditions. We assessed the correlation between outcomes of etching processes and AC impedance methods. Changes of copper etching mechanisms with variation of the etching solution pH were revealed by AC impedance measurements.

For this study, electroless deposition of aluminum（Al）was examined using baths of AlCl₃/LiAH₄/ether solvents and catalysts formed on substrate surfaces. Deposition of a thick electroless Al layer requires a Cu substrate, a Ti compound catalyst, and diethyl ether or dibutyl ether solvents. From 15-μm-thick Al deposits obtained from 2 h deposition time, the rate of Al deposition was found to be 15±2 μm h^－1. Results show that adding dicarboxylic acids such as glutaric acid and thiomalic acid to the bath can improve the deposited Al surface brightness. As an exemplary application of electroless Al, deposition of Al on the surface of cup-stacked 30-50 nm diameter carbon nanotubes was achieved with a bath including AlCl₃/LiAH₄/diethyl ether and a Ti catalyst.