Electrolytic condenser electrode and aluminum foil therefor

摘要

A raw aluminum foil for use to prepare electrolytic condenser electrodes has an aluminum purity of 99.9% or higher and contains 50-500 ppm of Mg. A method of etching the raw foil to prepare the electrodes consists of a primary etching step and a secondary etching step, and the primary etching is conducted in an aqueous bath containing 3-10% by weight of HCl and 10-40% by weight of H2SO4, at 70 DEG -90 DEG C. and with a current density of 10-40 A/dm2. The secondary etching is conducted electrolytically or chemically in a further bath containing 3-10% by weight of HCl, with or without 1% or less of H2C2O4 added to the further bath, at a bath temperature of 70 DEG -95 DEG C. and with a current density of 0-10 A/dm2.