A process of etching aluminium anode foil for high voltage electrolytic capacitors

摘要

Aluminium electrolytic capacitor anode foil of a high cubic texture etched in two step process by treating the foil in an electrolyte bath containing 3% hydrochloric acid and 1% aluminium as aluminium chloride under the influence of a direct current and at a temperature of 75 DEG C, and in a second step treating said etched foil in an aqueous bath of 8% nitric acid and 2.6% aluminium as a nitrate at a temperature of 85 DEG C for 5 to 7 minutes. The foil thus etched has a significantly higher capacitance resulting from a greater density of tunnels, an elongation of the tunnels, and a faily linear tunnel structure.