A printed circuit board includes: a plurality of layers including attachment layers and routing layers; and via patterns formed in one or more of the plurality of layers, each of the via patterns including: first and second signal vias configured to accept contact tails of signal conductors of a connector; ground vias configured to accept contact tails of ground conductors of the connector; ground shadow vias located adjacent to each of the first and second signal vias; and non-plated holes located between each of the ground shadow vias and the signal vias. Different layers of the plurality of layers may have different antipad configurations.