Creepage DRC does not work

Layout
1

Hello,
I have problems with the new creepage feature. This layout creates a DRC error, which correct:

drc-error
drc-error908×623 35.1 KB

Now I move the trace just a bit unter the slot. This layout creates no DRC error.
drc-no-error
drc-no-error883×580 25.2 KB

Am I doing something wrong?

My custom rules are:

(rule mains
   (constraint clearance (min 4mm))
   (condition "A.hasNetclass('Mains_Line') && B.hasNetclass('Mains_Neutral')"))

(rule mains2
   (constraint creepage (min 6mm))
   (condition "A.hasNetclass('Mains_Line') && B.hasNetclass('Mains_Neutral')"))

Minimum example:
creepage-test.zip (8.7 KB)

Version:
Application: KiCad x86_64 on x86_64

Version: 9.0.0-9.0.0-2~ubuntu24.10.1, release build

Libraries:
wxWidgets 3.2.5
FreeType 2.13.3
HarfBuzz 9.0.0
FontConfig 2.15.0
libcurl/8.9.1 OpenSSL/3.3.1 zlib/1.3.1 brotli/1.1.0 zstd/1.5.6 libidn2/2.3.7 libpsl/0.21.2 libssh2/1.11.0 nghttp2/1.62.1 librtmp/2.3 OpenLDAP/2.6.8

Platform: Ubuntu 24.10, 64 bit, Little endian, wxGTK, X11, ubuntu-xorg, x11

Build Info:
Date: Feb 20 2025 21:17:37
wxWidgets: 3.2.5 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.83.0
OCC: 7.8.1
Curl: 8.9.1
ngspice: 43
Compiler: GCC 14.2.0 with C++ ABI 1019
KICAD_IPC_API=ON

Locale:
Lang: en_GB
Enc: UTF-8
Num: 1,234.5
Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)

2

Please use “Preformatted text” for rules, I changed it for you as a model.

3

It is correct.
There is a nice feature for v9 Post-V8 New Features and Development News - #62 by Drinausaur

It showns this a bit clearer. It’s basically creepage (surface around slots) and clearance (through air)

In your 2nd shot the track has been moved so there isnt a straight line path to the other track and thus the creepage distance has (hopefully) been increased enough to pass your 6mm constraints

4

Unfortunately not, the creepage distance is significantly shorter than 6 mm. Even if I set the design rule to 10 mm, the DRC reports nothing.

5

Try one of the RCs for 9.0.1. There were several creepage bugs fixed, including one where creepage results disappear on subsequent runs.

1 Like
6

I have repeated the test with version 9.0.1-rc2 on a windows pc, but the result remains the same. This time with 10 mm creapage limit. For me it looks like he can’t go round the slot in a curve, only in a straight line.

This gives an drc error, which is correct

drc-error
drc-error1157×547 27.5 KB

This gives no drc error, despite creepage is something like 4 mm (limit 10 mm)
no-drc-error
no-drc-error1159×550 24.2 KB

7

Then I’d report a bug (help-> report a bug) with a demonstration project attached.

8

I have sent a bug report #20480

1 Like
9

Edit: old post deleted
Oops.

Brainfart. Although I know the differences between creepage and clearance, I still managed to mix them up somehow.

10

Correct me if I am wrong, but clearance is the connection over air (shortest possible connection between two points) and creepage is the connection over a surface, which can be increased with grooves and slots. So clearance is always smaller/equal than creepage

clearance-creepage

11

You are right and this bugs me as these terms are quite clear.
I keep meaning to raise a PR to have this fixed but I haven’t quite figured out what a viable suggestion is as an alternative