On Thu, Mar 19, 2009 at 10:28:46PM +0100, Pedro Martin wrote: > I've seen the first link and yes, it says so. > I could understand a zone clearance around the fiducial and not a solder mask > clearance. In any case, they are the experts, not me.
As I get it the basic requirements are: ** provide as much optical contrast between the fiducial and the surrounding area ** keep the surrounding area as optically even as possible The resist-free rule may be related to the second requirement. The resist may be subject to (optical) imperfections much easier than the PCB substrate, thus the rule to keep it out of the fiducial area. It would be helpful to have a keep-out layer in Kicad. :) Mihai
