I’m trying to lay out what I think is a simple diff pair case: 6.787mils trace, 5mils space. Board requirements are 5 mils trace/space, and my poured ground polygon these traces run through has 6 mil clearance set so that’s not coming into play here.
It seems I can’t avoid DRC issues on these traces, and I don’t quite get why. I’ve tried routing, then push-n-shove to tidy everything up, which results in lots of flags, and also routing with a minimum grid set and then not touching anything after.
Here’s an example image:
In essence, I get a DRC flag saying the traces are spaced at 4.98 mils on the corners, even though the settings are all 5 mils and best I can possibly measure, that’s obeyed.
If I then go into board settings and relax the spacing requirements on the diff pair to 4.5 mils just for kicks, I still get the same exact error (as if I didn’t change the spacing requirement at all).
I went ahead and ripped up all these tracks and re-routed one set with the ultra-fine grid. Now I’m getting a new error:
Error: Differential pair gap out of range (...) minimum gap: 5.00 mils; actual: 5.00 mils)
This all sure feels like badly-handled floating point errors in the DRC engine, but I’m a KiCad novice so I’m not sure if this is normal, or a bug, or known, or “this is the workaround I use.”
Any tips from the experienced?
Edit: I’m getting the sense that maybe if I set the diffpair spacing to 5.01mils, that might do the trick in terms of push-n-shove post-route. Edit: nah, that helps, but doesn’t fix.