>Ralllllphoooo - are you going to stimulate comments from the CAD community

	Here we go!

	We are right in sync on this one, although my reasoning comes
	more from the electrical side.  Minimum spacing equates to max-
	imum coupling, in many cases.

	Most of today's routers apply spacing rules as "minumum" and then
	pack the etch in at that value until a threshold accumulation is
	crossed, at which time the spacing gets incremented to the next
	acceptable value, with another threshold, etc etc.  The target is
	based on "how much noise can we tolerate".

	That's why we've travelled down another path, for years I've said
	"look not at the traces, but at the spaces".  Our autorouting
	structure starts with a wide spacing and jumps to minimum only in
	order to get around an obstacle.  Here the target is more like,
	"how little noise can we accumulate".

	In the early 90's I tried to dialogue router vendors on this point,
	but my cries fell on deaf ears.  Good thing that hasn't stopped us.

	Of course, this does nothing for the 1/4 of the board with nothing
	on it, that's a designer's placement skills vs the engineering re-
	quirements vs the utilization of the board.  There's still a need
	for thieving.

	Have a good weekend (if you didn't already ;)

        Jeff Seeger                             Applied CAD Knowledge Inc
        Chief Technical Officer                      Tyngsboro, MA  01879
        [log in to unmask]                               508 649 9800

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