A multilayer printed circuit board having clustered blind vias in power layers to facilitate the routing of signal traces in signal layers. A portion of the blind vias in the power layers are grouped together to form a cluster of blind vias. Corresponding signal routing channels are provided in the signal...http://www.google.de/patents/US6720501?utm_source=gb-gplus-sharePatent US6720501 - PC board having clustered blind vias
