The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 26, 1983
Filed:
Dec. 10, 1981
Constantine I Courduvelis, Orange, CT (US);
Enthone Incorporated, West Haven, CT (US);
Abstract
An improved process for dissolution of metals by etching, and particularly the etching of copper in printed circuit board processing or the like, using an aqueous H.sub.2 O.sub.2 --H.sub.2 SO.sub.4 etching solution, in which the concentration of H.sub.2 SO.sub.4 in the etching solution is allowed to decrease during use of the etching solution from an initial, relatively high level at the time the etching solution is put into use, to a final, relatively low level. When a predetermined concentration of dissolved etched metal exists in the etching solution, the etching solution is removed from use, H.sub.2 SO.sub.4 is added to increase the concentration of H.sub.2 SO.sub.4 in the etching solution to approximately the initial, relatively high level, and the metal is precipitated out of the etching solution.