| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an aluminum foil coil for an electrolytic capacitor in which capacitance can be improved by improving its electrolytic properties to expand the surface area of foil, and furthermore, bending strength can be increased. SOLUTION: At first, aluminum foil contg., by weight, >=99.8% Al, and the balance inevitable impurities is degreased. Next, coil stock in which this aluminum foil is formed into a coiled shape is arranged in an annealing further and the inside of this annealing furnace is initially exhausted to a pressure of <=1×10<-2> Torr. Then an inert gas is flown into the annealing furnace to regulate the pressure in the annealing furnace to 500 to 950Torr, and in a state in which this pressure is held, the inside of the annealing furnace is heated to 350 to 450 deg.C. After that, the inside of the annealing furnace is exhausted to a pressure of <1Torr, moreover, an inert gas is again flown into the annealing furnace to regulate the pressure in the annealing furnace to 500 to 950Torr, and in a state in which this pressure is held, the coil stock is annealed at 450 to 600 deg.C for >=1hr.
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