Aluminum electrolytic capacitor and method for producing cathode foil for aluminum electrolytic capacitor

摘要

PROBLEM TO BE SOLVED: To provide a cathode foil which is capable of lessening an electrostatic capacity change in an aluminum electrolytic capacitor. SOLUTION: An aluminum foil, where metal such as Ti, Zr, Hf, or Nb or its oxide or nitride is evaporated is dipped into a solution which contains phosphoric acid, phosphorous acid, or hypophosphorous acid or its salt and thermally treated for the formation of a cathode foil. An etched foil, whose surface is roughened through an electrochemical or a chemical method, is used as the aluminum foil. Furthermore, this thermal treatment is carried out in the temperature range of 100 to 500 deg.C.