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:
Jan. 26, 1999
Filed:
Apr. 08, 1997
Paul William Coteus, Yorktown Heights, NY (US);
Stephen Leo Tisdale, Endwell, NY (US);
Alfred Viehbeck, Fishkill, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
This invention describes a new process for the selective isolation of through holes in the production of a multi-layer printed circuit card which allows for substantially smaller holes through reference layers to be built, leading to substantially better electrical isolation of signal traces on adjacent wiring layers, and for substantially improved current carrying capacity in the reference layers. This invention also describes a process to allow reference layers of different thickness from adjacent signal layers, even if they are part of the same `core`. Several different process flows are disclosed, leading to substantially the same structure but with varying degrees of complexity and quality of the finished product.