Kicad 9.0.2
I’m receiving some solder mask aperture bridging DRC errors I don’t remember encountering before, and with the standard 1mm-2mm Fiducial footprint. Essentially the 2mm diameter mask is exposing the center (no net) fiducial copper dot, and my main zone pour around it is only 10mil away and so is also exposed.
I really don’t remember this happening before even though I use this footprint frequently. No matter, I copy and duplicate the fiducial footprint and add a circle on the margin layer to create a copper keepout. Re-link footprints to the new fiducial design, update layout, and now I receive a new error that the feature on margin is violating the board edge clearance of 15mil by being 2.81mil away:
Even though I’m measuring from the center of the 5mil wide margin circle here, I’m clearly >15mil away from edge cuts. Furthermore, that design rule setting the 15mil clearance is specifically “Copper to edge clearance”. Why is a feature on margin considered copper?
It looks like it’s actually complaining about the clearance from the margin circle to the no net fiducial pad.
Fine, I go into the footprint settings in PCB Editor and change the value in “Clearance Override” to 0mil and hit enter. Re-run DRC, same error persists. I have tried for both the pad and the footprint itself.
I don’t think margin layer is the right answer as it will keep copper out on all layers.
Now I try drawing a graphical circle on F.Cu, 1mil wide, outside of the center fiducial dot.
I save, re-import and now get the error that the soldermask is bridging items with different nets, the fiducial pad which has no net and the new graphical circle I just drew.
What is going on here? How can I enforce copper keepout inside of the fiducial?
I really do not remember this ever being an issue before, has something changed in the fiducial footprint library or in the application that impacts this?
UPDATE: I added a pad clearance override to the fiducial pad in the footprint and set it outside of the mask area, and this resolved the issue. I have never encountered these errors with this footprint before so something must have changed somewhere else. Either way, resolved.