Method for manufacturing anode foil of aluminium electrolytic capacitor

A method of manufacturing anode foil for aluminum electrolytic capacitors, said method comprising:

• dipping etched aluminum foil into pure water having a temperature of 90° C. or higher so as to form a hydrated film on the foil;
• attaching organic acid to a surface of the hydrated film;
• performing a main chemical conversion treatment on the aluminum foil with application of a formation voltage after said attaching of organic acid;
• performing a depolarization treatment on the aluminum foil after said performing of the main chemical conversion treatment;
• and
• performing a follow-up chemical conversion treatment on the aluminum foil after said performing of the depolarization treatment;
• wherein the main chemical conversion treatment includes a plurality of first stages and a second stage after the plurality of first stages, wherein in each stage of the plurality of first stages, the aluminum foil undergoes chemical conversion while being dipped into an aqueous solution of phosphate, and in the second stage, the aluminum foil undergoes chemical conversion while being dipped into an aqueous solution having a solute different from the solution of phosphate,
• wherein a formation voltage in a last stage of the plurality of first stages is 80% or greater of a formation voltage in the second stage.