Comment 28 for bug 1563744

Honestly Kicad should be 100% perfect output since it is electronic. There
should not be any misalignment that happens in kicad that will only be
exaggerated by the manufacturer which is allowed to have misalignment since
there is human and mechanical error in the process.

On Mon, Aug 27, 2018 at 3:57 AM Rene Poeschl <email address hidden>
wrote:

> I just noticed another inconsistency. Polygon pads behave differently to
> normal pads. They use rounded corners on the soldermask. (So they look
> like solution 1)
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1563744
>
> Title:
> Zone vs. Soldermask clearance collisions at corners
>
> Status in KiCad:
> Triaged
>
> Bug description:
> If you place an SMT pad in a zone, due to the way the zone clearance
> gets rounded corners it can mean there's a little bit of copper that
> overlaps into the pad area.
>
> For example: the attached screenshot shows a zone of clearance 0.01in
> inside which is placed an SMT pad of mask clearance just under 0.008in
> (the actual value 0.007874015748in being 0.2mm). You would expect that
> this is perfectly safe; a nice 0.002in of safety margin between the
> solder mask opening and the copper zone.
>
> But you'd be wrong. The problem is that the zone clearance only
> applies vertically and horizontally from the pad; the cleared area
> within the zone gets a rounded corner of radius 0.010in, meaning it
> could only guarantee clearance of a square corner at most 0.00707...in
> (0.01in * sqrt(2)) wide. The mask clearance of 0.008in gives a tiny
> margin of bare copper from the filled zone exposed within the pad
> clearance area.
>
> This isn't just a rendering issue; I have had a bad copper run of
> boards from the fab because of actual spilled out copper in these pad
> areas, causing grounding shorts to the pads when soldered.
>
> As a workaround for these collisions I've been manually editing the
> per-pad Cu clearance settings and increasing it on any pad that would
> be affected. I'd prefer to leave the global zone clearance at a nice
> small 0.01in though because I need to route some grounding pour
> between TTH connector pads, so that can't be too big.
>
> To manage notifications about this bug go to:
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>

--
From,
Jt Whissel