| 摘要 |
PROBLEM TO BE SOLVED: To suppress reduction in the electrostatic capacitance of an electrolytic capacitor as a finished product by forming an oxidized film on an aluminum foil on which a metal such as Ti, Zr, Hf, or Nb or an oxide or a nitride thereof is deposited by evaporation. SOLUTION: Increased pH at the cathode foil interface is one of the factors responsible for reducing the electrostatic capacitance of an electrolytic capacitor as a finished product. A solution to this problem is to form an oxidized film on a cathode foil by anodization in advance. This allows one to control reactions at the cathode foil interface even when its pH increases, and thus reduction in the electrostatic capacitance can be suppressed. Specifically, Ti is deposited on an electrochemically etched aluminum foil by a vacuum evaporation method, after which the foil is subjected to an oxidized film forming process through the application of 1 V in an aqueous solution of ammonium phosphate. Using the resulting foil as a cathode foil, an electrolytic capacitor whose rating is 10 V-330μF is prepared. As a result, changes in the electrostatic capacitance of the electrolytic capacitor as a product can be reduced remarkably and hence its reliability can be improved significantly.
|
