Al, In my own experience, I try to adhere to a 100 mil copper free edge to the board outline. But in some PC Boards I did have to go to a minimum of 25 mils away from the board edge. I suppose if you had your gnd plane out to the edge and your pwr plane to the edge also, a possibility of a short could exist. I think this would be a bad Design practice. I like all of my pc boards to work long term, so I try to increase all of my clearances whenever possible. Karl Bates Zenith Electronics [log in to unmask]