1998 年 49 巻 6 号 p. 643-648
The large specific surface area on a low voltage-use aluminum electrolytic capacitor electrode was produced by alternating-current etching in a chlorine solution. The effect of sulfuric acid added to the 3.6% hydrochloric acid solution etchant on etch morphology was examined by Auger spectroscopy, electron microscopy, and galvanovoltammetry. Electrostatic capacitance, pit size, and amount of aluminum hydroxide formed during etching at 1∼50Hz in 3.6%HCl/n%H2SO4(n=0∼1) solution at 333K were determined. A deeper etched porous layer was produced in a 3.6%HCl/0.25%H2SO4 solution than in a 3.6%HCl solution, with general dissolution prevented and surface film formation facilitated by the additive. The atomic ratio O/Al as calculated from the O (507eV) and Al-O (55eV) peaks of the surface film developed in a 3.6%HCl/0.25%H2SO4 solution is 1.8∼2.0 higher than 1.5 for the etched film in a 3.6%HCl solution.