> You want rounded clearances, but square soldermask apertures. > > In the example above, all but the pad would be covered with soldermask.
Except that fabs won't let you do that; they want the mask to be bigger than the pad by some amount, in case of registration errors. If you're using a 3 mil gap and 6/6 rules, an offset mask could uncover some adjacent copper near the corner. With a 3 mil gap (i.e. +- 3 mil mask accuracy), you could end up with 6 mil on two adjacent sides, or 8.4 mils from the pad's corner to the mask's corner. If you have a 6 mil copper clearance, you've just uncovered 2.4 mils of the wrong copper. _______________________________________________ geda-dev mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev
