Cisco Technology, Inc.

David Senk

Aritharan Thurairajaratnam

Joe D Dickson

Ashok Kumar Singh

Jennifer Oliver

Musan Hu

In one embodiment, an apparatus includes a plurality of layers in a circuit board, each of the layers comprising a fiber weave, two plated holes extending through the layers and connecting two or more of the layers, and a non-plated hole interposed between the plated holes. The non-plated hole passes through a potential CAF (Conductive Anodic Filament) migration path along the fiber weave to prevent CAF formation between the plated holes.

Circuit board with non-plated hole interposed between plated holes to prevent formation of conductive anodic filament

A printed circuit board (PCB) stack-up has a signal via configured to transmit a signal through at least two different layers of the PCB stack-up, a reference structure that is at least a portion of a return path for the signal; and an unplated via disposed in an area surrounding the signal via. The unplated via is disposed in the area surrounding the signal via to improve the characteristic impedance of the signal via.

Multiple layer printed circuit board with unplated vias

Methods and apparatus for creating independent circuit connections within a through-hole of a substrate are described. According to one aspect of the present invention, a method includes defining a through-hole in a substrate, applying a conductive plating to a holewall of the through-hole, and selectively removing at least a first area of the plating. The through-hole has a height relative to a first axis, and the perimeter of the through-hole at each point along the first axis is approximately the same. Selectively removing the first area of the plating includes defining second areas of the plating. At least one of the plurality of second areas does not span a height of the hole.

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San Ramon, CA, United States of America

David Senk