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. 22, 1979
Filed:
Dec. 12, 1977
Warren A Alpaugh, Chenango Forks, NY (US);
Michael J Canestaro, Endicott, NY (US);
Theron L Ellis, Vestal, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A cleaning process for high aspect ratio through holes of multilayer printed circuit boards assures the removal of any loosened fiberous material or epoxy smears in the through holes and also provides an inverted 'T' structure at the innerplanes of the internal conductive circuits within the printed circuit board sandwich. The inverted 'T' structure helps to move the contact point between the plating of the through hole and the internal circuit lines further into the circuit board, thereby eliminating the 'Z' stress at the edge of the innerplane. This process is accomplished by first vapor blasting the through holes, soaking the board in a suitable solvent to loosen any fibers or smears on the circuit innerplanes of the board, removing the excess solvent from the through holes and then feeding a unilateral stream of a cleaning solution through the holes, the cleaning solution operating to remove excess fibers and smears in the through holes and to produce a slight, uniform etchback of the metal innerplanes of the printed circuit boards. Thereafter, the solution may be reduced and any excess cleaning solution is removed.