PURPOSE: To manufacture an Al foil or combining high tensile strength with high electrostatic capacity by subjecting a high-purity Al plate to process annealing accompanied by rapid cooling and then to low temperature process annealing.
CONSTITUTION: An Al slab of ≥99.50% purity is cast, homogenized, and hot- rolled. The resulting sheet is heated to 450-600°C and cooled down to ≤300°C at ≥50°C/min cooling rate to undergo primary process annealing. Subsequently, after subjected or not subjected to cold rolling, the above sheet is heated to 150-300°C undergo secondary process annealing. By the above secondary process annealing, the etching starting point can be controlled, and the electrostatic capacity of the Al foil for electrolytic capacitor cathode can be increased.