Max, We also are sensitive to EMI problems and are aware of the problems caused by excessive anti-pad sizes, namely reducing the integrity of the ground and power planes. There is a IPC spec concerning clearance area in planes in IPC-D-275 section 5.3.2.4. According to this spec, there is a .010" minimum clearance between the edge of the land and the plane. A fabrication allowance should be added to this also. For us, we use a .035" via pad with a .018" finished drill size. If we were to follow this spec, we should have a .020" clearance using the Level C fabrication allowance. This would translate to a anti-pad of .075", (pad size + .040" for .020" clearance). Having said this, we don't follow the spec. We use a much smaller anti-pad, .055" which gives us a .010" clearance. I have asked our board fabricators about this reduced clearance and they told me this is not a problem. Hope this helps. Danny Gross PCB Designer E-Mu Systems, Inc. Scotts Valley, CA **************************************************************************** * The 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. * ****************************************************************************