ALUMINUM ELECTROLYTIC CAPACITOR

PURPOSE:To miniaturize an aluminum electrolytic capacitor while lowering leakage currents by impregnating an element, in which an anode obtained by forming a high purity aluminum film having the shape of a columnar projection onto the surface of a metallic foil and anodizing the film and a cathode foil through a separator, with an electrolytic solution for drive. CONSTITUTION:An electrolytic solution for drive is housed into a closed-end cylindrical case 1 together with a capacitor element 2. The element 2 is constituted by winding an anode foil 3 acquired by shaping high-purity aluminum having the shape of a columnar projection onto the surface of a metallic foil through evaporation and anodizing aluminum, a cathode foil 4 oppositely faced to the anode foil 3 and composed of aluminum, and separators 5 interposed among the anode foil 3 and the cathode foil 4. The thickness of the metallic foil used for forming the anode foil 3 extends over 15-40mum, aluminum is evaporated onto the surface of the metallic foil in an inert gas atmosphere having gas pressure of 1X10-8X10Torr, and the diameter of the columnar projection is shaped in 0.1-2mum. Accordingly, an aluminum electrolytic capacitor can be miniaturized while leakage currents can be reduced.