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

摘要

PROBLEM TO BE SOLVED: To provide an aluminum foil for an electrolytic capacitor wherein a tunnel-like etching pit is formed and high electrostatic capacity is attained while the electrostatic capacity on a foil surface is uniform at an arbitrary part. ;SOLUTION: Relating to an aluminum foil for an electrolytic capacitor, a foil surface comprises an oxide coat of film thickness 30-80 , the foil comprises such high purity Al of purity 99. 9% as containing B by 0.0-20 ppm while the B is concentrated step by step at a surface layer part of the high purity Al, B content Y₁ from the high purity Al surface as deep as at least 0.3 m at an upper layer part of the surface layer part is 5-1000 ppm while B content Y₂ from the high purity Al surface as deep as at least 1.0 m at a lower layer part of the surface layer part is 1000-100 ppm, with Y₁Y₂.;COPYRIGHT: (C)1999,JPO