| 摘要 |
PURPOSE:To obtain an electrode foil having large electrostatic capacitance, and miniaturize a capacitor, by dipping an Al foil in water solution having an action to eliminate a natural oxide coating film and form a protective film, and applying an etching treatment to the Al foil, which increases an initial current density gradually. CONSTITUTION:An Al foil is dipped and treated in a water solution having an action to eliminate a spontaneously oxidized film and form a protective film on the surface. The Al foil is subjected to an etching treatment in which an initial current density is gradually increased. The time necessary to rise up the initial current density in the etching is more than or equal to 3 seconds. Thereby, an electrode foil having large electrostatic capacitance can be obtained to miniaturize a capacitor.
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