ALUMINUM ELECTROLYTIC CAPACITOR

摘要

PROBLEM TO BE SOLVED: To provide a highly reliable aluminum electrolytic capacitor, which is capable of easily improving prevention of leakage ofan electrolyte solution under high temperature and high humidity environment without using a specific butyl rubber sealing material, and further improving the prevention of even short circuit due to dissolution and reprecipitate of copper existing on the surface of a negative electrode aluminum foil. SOLUTION: A bulk copper content of a negative electrode aluminum foil is set to be within 0.03 to 0.35%. A copper content on the surface of the negative electrode aluminum foil is set 0.5μg/cm2 or less per unit area of the foil, using a value obtained by measuring with atomic absorption spectroscopy the amount of copper dissolved in an aqueous 3% nitric acid solution after the foil has been taken out with dissolving the surface of the foil by dipping the foil in the 3% nitric acid solution at 45 deg.C for 3 minutes. Further, a spontaneous potential in the electrolyte solution of the negative electrode aluminum foil is-s$ 0.50 V or more with respect to the potential of a saturated calomel electrode.