Abnormal zone to pad clearance for rrect pad

[Jules]

Can someone tell my why the S-pad might have a different zone clearance than the R-pad? The pads in the footprint have the same settings. I’ve looked through all the zone and pad settings but couldn’t find anything.

(pad T thru_hole roundrect (at -7.23 17.45) (size 3.75 3) (drill 1.6) (layers *.Cu *.Mask) (roundrect_rratio 0.25))
(pad R thru_hole roundrect (at -7.23 11.1) (size 3.75 3) (drill 1.6) (layers *.Cu *.Mask) (roundrect_rratio 0.25))
(pad S thru_hole roundrect (at -7.23 4.75) (size 3.75 3) (drill 1.6) (layers *.Cu *.Mask) (roundrect_rratio 0.25))

I can set the zone connection locally to solid instead of thermal relief, but i’d rather have thermal reliefs…
Is it due to the zone rounding? I figure that works okay because it has no extra clearance around the non-zone-connected pads. It has something to do with the thermal spokes but what…

Zone clearance and min width, antipad clearance are 0.254 mm, spoke width 0.255mm, poly fill high resolution.

[Album] imgur.com

With zone outlines you can see the different clearance - is it due to rectangular pads behaving differently (with spokes)?

[Album] imgur.com

Application: kicad
Version: (5.0.2)-1, release build
Libraries:
wxWidgets 3.0.4
libcurl/7.61.1 OpenSSL/1.1.1 (WinSSL) zlib/1.2.11 brotli/1.0.6 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) nghttp2/1.34.0
Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.68.0
OpenCASCADE Community Edition: 6.9.1
Curl: 7.61.1
Compiler: GCC 8.2.0 with C++ ABI 1013

Build settings:
USE_WX_GRAPHICS_CONTEXT=OFF
USE_WX_OVERLAY=OFF
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_WXPYTHON=ON
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=ON
KICAD_USE_OCC=OFF
KICAD_SPICE=ON

[paulvdh]

There are different settings for “Clearance” and for “Antipad Clearance”

“Antipad Clearance” is the clearance between the filled zone and pads which are part of that zone.
The setting can be reached in the dialog by hovering over the zone and pressing “e” from edit.

You already found the right dialog, just looked over the setting.

[Jules]

I can set the antipad clearance to 0, with other clearances to 6 mil and spoke width 7 mil, but there’s still something that’s causing the zone not to hug the pad correctly.

Mind you, the square zone vs the rounded zone around the pad is just cosmetical, but I want to know

[Album]

Try oval pads vs rounded rectangular pads - here seems to be a difference afaict.
As soon as you start going over a corner size of 10% you can see the effect.

[Rene_Poschl]

This could be a bug in the antipad algorithm. Maybe that one does not take rounded rectangle into account. I suggest you open a bug report.

[Jules]

Done - https://bugs.launchpad.net/kicad/+bug/1814756

I wasn’t sure if this was me being a newbie or that I wrongly remembered that the rrect pads were a stable feature. Ah well, I’m glad to have spotted it in case its an actual bug.

[paulvdh]

I think I can confirm this bug.
I just did a simple test with a default library footprint:

Resistor_SMD:R_1210_3225Metric_Pad1.42x2.65mm_HandSolder

Which also has rounded rectangles.

When I zoom in it looks like the antipad radius in the filled zone on the GND pad is too small. The clearance of the other pad has a much bigger radius. It seems like the former is calculated from the pad clearance and not from the zone clearance.

Application: kicad
Version: 5.0.2+dfsg1-1, release build
Libraries:
wxWidgets 3.0.4
libcurl/7.63.0 OpenSSL/1.1.1a zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh2/1.8.0 nghttp2/1.36.0 librtmp/2.3
Platform: Linux 4.19.0-1-amd64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
Boost: 1.67.0
OpenCASCADE Community Edition: 6.9.1
Curl: 7.62.0
Compiler: GCC 8.2.0 with C++ ABI 1013

Build settings:
USE_WX_GRAPHICS_CONTEXT=OFF
USE_WX_OVERLAY=OFF
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_WXPYTHON=OFF
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=ON
KICAD_USE_OCC=OFF
KICAD_SPICE=ON