PRODUCTION OF ELECTRODE FOIL FOR ALUMINUM ELECTROLYTIC CAPACITOR

PURPOSE:To produce the title Al foil having high diffusing surface magnification at a low cost by using an etchant in which meltage of Al is reduced as etching proceeds at the time of applying electrolytic etching to the surface of an Al foil by using a hydrochloric-acid solution containing film-forming additives in which concentration and temp. are specified, respectively. CONSTITUTION:A new hydrochloric-acid solution 14 of 3-25% concentration containing film forming additives is poured into a third etching tank 13, fed in succession into a second etching tank 12 and a first etching tank 11, and discharged from the first etching tank 11. By the above constitution, the temp. of the hydrochloric-acid solution 14 is regulated to 10-100 deg.C, and an Al foil 15 is successively fed by means of rollers 16 from the direction of the first etching tank 11 toward the second etching tank 12 and the third etching tank 13. By this method, a solution of reduced Al meltage can be used in the latter stage of etching, and also diffusing surface magnification can be improved if etching temp. is lowered.