The effect of lead impurity on the DC-etching behaviour of aluminum foil for electrolytic capacitor usage

Abstract

The effects of lead impurity on the etched morphology of high purity aluminum foils for electrolytic capacitor applications were investigated in this work. The lead impurity was either present in as-received aluminum foils or deposited purposely on the foil surface through an immersion-reduction reaction. The amount and distribution of deposited lead varies with the lead content in as-received foil. The as-received foil with higher lead content gave a higher concentration and a more uniform distribution of deposited lead. Uniformly distributed vertical tunnel etchings were obtained when high lead foil, formed by immersion as-received high lead foil in Pb(NO3)(2) solution, was subject to DC-etching. For the as-received lower lead foils, the deposited lead was concentrated in rolling lines which resulted in surface etching along rolling lines. Both the surfacial and cross-sectional etching morphologies are presented in this study, together with the etching mechanism discussed. Copyright (C) 1996 Elsevier Science Ltd.