This is a good idea. Especially if you have high speed signals running near the board edge. The only problem I see is where you say to "...tie the external planes and the internal ground plane together..." I think you probably meant to say "...tie the external planes and the internal GUARD RINGS together..." This prevents any possibility of the shield becoming a part of the return path. Don Walker [log in to unmask] > to run a guard ring of ground around the periphery of the board on all > layers and tie the external planes and the internal ground plane > together through closely spaced (.25 inch) vias only at the guard > ring. *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************