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:
Dec. 29, 1992
Filed:
Feb. 22, 1991
Randal D King, Wilmington, DE (US);
Eda R Montgomery, Wilmington, DE (US);
McGean-Rohco, Inc., Cleveland, OH (US);
Abstract
Improved through-hole plating of printed circuit boards, wherein the ratio of the printed circuit board thickness to the diameter of at least one through hole is greater than 3 to 1, is achieved by a high-throw acid copper plating bath of this invention. The high-throw acid copper plating bath comprises an aqeuous solution of (A) copper sulfate, (B) sulfuric acid, (C) chloride ion, e.g., hydrochloric acid, (D) a carrier, (E) a brightener, and (F) an alkali metal salt; wherein the plating bath has a pH of not greater than about 1, the concentration of the hydrochloric acid is from about 6.0.times.10.sup.-4 to about 1.8.times.10.sup.-3 moles/liter, and the mole ratio of copper sulfate:sulfuric acid is not greater than about 1:25. Unlike previous high-throw acid copper plating baths, the bath of this invention contains an alkali metal salt. The use of the alkali metal salt makes it possible to maintain a lower acid concentration resulting in easier maintenance and more consistent plating. In addition this high throw process makes it possible to obtain in a substantially shorter time, plated circuits and through-holes with an acceptably high aspect ratio.