Electrical performance of via transitions in the presence of overlapping anti-pads

The electrical performance of vias in multilayer PCBs is investigated. In particular the resonance effect due to overlapping anti-pads is characterized and an analytical formulation based on the dimensions of the cavity formed by the anti-pads and the vias is used to predict such a resonance. A prototype board is fabricated and measured results confirm the predicted results obtained from 3D electromagnetic simulation.