| 摘要 |
PROBLEM TO BE SOLVED: To provide a method or producing aluminum foil for an electrolytic capacitor where, when aluminum foil for an electrolytic capacitor is largely subjected to annealing treatment at a time, an oxide film is suitably formed, and satisfactory etching properties are obtained, so as to be able to produce an electrolytic capacitor of high quality. SOLUTION: When aluminum foil coils whose total after rolling is≥1 ton are annealed, the annealing treatment is performed in an atmosphere having a dew point of≤-10°C and a hydrogen concentration of≥70%. The holding of the atmosphere is performed, e.g., in such a manner that gaseous hydrogen is continuously or intermittently fed during the annealing treatment. By the suitable holding of the dew point and hydrogen concentration in the annealing atmosphere, the growth of an abnormal oxide film or the like during the annealing is evaded, and an oxide film of high quality can be formed. As a result, satisfactory etching properties can be obtained, and an electrolytic capacitor of high quality can be obtained. COPYRIGHT: (C)2008,JPO&INPIT
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