Sprague Electric Company

Mulk A Arora

John J Randall, Jr

Walter J Bernard

Aluminum electrolytic capacitor foil is etched by subjecting the foil to etching for a period of time, followed by a rest period during which no etching takes place, subjecting the foil to etching for another period, followed by another rest period, and repeating these steps until the foil is etched to the desired level. An alternating current is used.

Intermittent AC etching of aluminum foil

Aluminum electrolytic capacitor foil is etched in a bath containing 0.7 to 2.O M hydrochloric acid, 0.2 to 0.5 M hydrated aluminum trichloride, and 0.02 to 0.4 M phosphate ion while subjected to the action of alternating current at 35 to 55.degree. C.

AC Etching of aluminum capacitor

Aluminum electrolytic capacitor foil is etched in a bath containing 1.0 to 1.8 M hydrochloric acid, 0.25 to 0.5 M aluminum chloride, 0.2 to 1.0 M phosphoric acid, and 1.0 to 2.0 M chromium trioxide while subjected to the action of alternating current at 35.degree. to 55.degree. C.

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Williamstown, MA, United States of America

Mulk A Arora