It is good design practice to allow a minimum of .010" from
          any plated feature (pad or trace) to the board edge.
          Bringing copper right to the board edge makes for possible
          rough edges where the metal has been cut into by the
          fabricator's router bit.  Since the overall dimension of the
          pcb has a tolerance, the .010" is recommended.
          I, too, have seen designs where a plated hole has been "cut
          in half" at the board edge.  I have also seen the plating
          yanked out of the hole wall when the router bit cuts through
          these holes.
          Even non-plated holes that come closer than .010" from the
          board edge can fracture the material when the router bit
          comes close to these holes.
          Tom Coyle
          Field Services Engineer
          HADCO Corporation
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