Aluminum foil electrode and its manufacturing method

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PROBLEM TO BE SOLVED : To obtain a capacitor having excellent electrostatic capacitance per unit area by effectively increasing a roughening ratio in an electrolytic etching process. ŽSOLUTION : An aluminum material having a composition containing 5 to 100 ppm Si, 5 to 100 ppm Fe, 10 to 100 ppm Cu, 0.1 to 5 ppm Pb and 1 to 50 ppm rare earth elements, and the balance Al with inevitable impurities is subjected to cold rolling in such a manner that the final cold rolling ratio is controlled to 15 to 25%, also, as final annealing, the same is held at 300 to 450°C for 2 to 6 hr, and is subsequently held at 530 to 600°C for 4 to 10 hr, so as to obtain aluminum foil for the anode of an electrolytic capacitor. At the inside to a depth of ≥0.5 μm from the surface, the content of Fe present as Al-Fe-REM precipitates and Al-Fe-Si-REM precipitates lies in the range of 20 to 60% to the average content of Fe by mass ratio. ŽCOPYRIGHT : (C)2006, JPO&NCIPI Ž