HIGH ELECTROSTATIC CAPACITY ALUMINUM FOIL FOR ELECTROLYTIC CAPACITOR HAVING UNIFORM ELECTROSTATIC CAPACITY

摘要

PROBLEM TO BE SOLVED: To provide aluminum foil for electrolytic capacitor, capable of can forming a tunnel-like etching pit, which can realize high electrostatic capacity and whose electrostatic capacity on the surface of foil is uniform at an arbitrary part. ;SOLUTION: In an aluminum foil for electrolytic capacitor, an oxide coat whose film thickness is 30-80 is provided on the surface of foil, foil is constituted of high purity Al which contains 0.1-20 ppm of MG and whose purity is not less than 99.9%, Mg is concentrated stepwise on the surface part of high purity Al, the Mg content Y₁ at a depth part to at least 0.3 m from the surface of high purity Al at the upper part of the surface part is 5-500 ppm, the Mg content Y₂ at a part to a depth of at least 1.0 m from the surface of high purity Al at the lower part of the surface part is 1-100 ppm, and Mg contents Y₁ and Y₂ are related by Y₁-Y₂.;COPYRIGHT: (C)1999,JPO