Patent ID: 7336502
Filing Date: 2008-02-26
Classification: H05K

Abstract:
1. A circuit board having multiple conductive layers separated by insulating layers, the circuit board comprising: at least two high-speed signal layers, each comprising multiple signal traces; a plurality of ground plane layers, each signal layer interposed between two of the ground plane layers; a conductively lined via connecting a first trace on one signal layer to a second trace on another signal layer, the via passing through a set of the ground plane layers, the set comprising at least two ground plane layers; and annular nonfunctional conductive pads on a first selected proper subset of the set of ground plane layers, the annular nonfunctional conductive pads arranged such that the outer surface of the conductively lined via is in electrical contact with the inner surface of each annular nonfunctional conductive pad, each annular nonfunctional conductive pad isolated from the remainder of its corresponding ground plane layer by a clearance.