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:
Sep. 07, 1993
Filed:
Feb. 06, 1992
Kenji Ishii, Tokyo, JP;
Takamasa Nakai, Tokyo, JP;
Hiroyuki Matsumoto, Tokyo, JP;
Kenichi Moriyama, Kanagawa, JP;
Mitsubishi Gas Chemical Co., Inc., Tokyo, JP;
Abstract
A process for producing a thin copper foil-clad circuit board substrate which comprises subjecting a copper foil-clad circuit board substrate (a) comprising an electrically insulating support overlaid on one or both sides with a copper foil having an average thickness of 12 .mu.m or more to etching with a copper-etching solution thereby to etch the whole surface of the copper foil at a predetermined etching rate selected from the range of from 0.01 to 0.4 .mu.m/sec, thereby to reduce the thickness of the copper foil on at least one side of the insulating support to 10 to 80% of its original thickness with the thickness variation of the remaining etched copper foil being within .+-.1.0 .mu.m on the basis of a desired thickness, wherein said copper foil-clad circuit board substrate (a) is one in which the surface of the copper foil is substantially free of adherent dust particles having an average particle diameter of 3 .mu.m or more.