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:
May. 28, 1991
Filed:
Jul. 05, 1989
Applicant:
Inventors:
Assignee:
Schering Aktiengesellschaft, Berlin and Bergkamen, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C25F / ; C25F / ; B44C / ; B44C / ;
U.S. Cl.
CPC ...
204130 ; 20415315 ; 20415316 ; 156627 ; 156642 ; 156644 ; 156668 ; 156902 ;
Abstract
A method of and an apparatus for etching an epoxy resin having a high backetching rate, in particular bores with printed circuit boards, with stable, strong, basic alkaline permanganate etching solution wherein the solution is stablized by electrochemical anodal oxidation, and permanganate and OH-ion concentration is controlled by measuring the same by using electrochemical and/or photometric measuring method with subsequent metering of the solution in accordance with deviation of a measurement value from a nominal value.