Front Solder mask aperture bridgers items with different nets

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Hello everyone:
I am making a 4 layer PCB, as is normal i define the planes, and the copper coverage of front and bottom.
But i get an unusual error on fiducial:Front Solder mask aperture bridgers items with different nets.
The spected behavior is simply an open on the copper plane.

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As is possible see, the fiducial has no connection (of course) and there is only one plane (gnd). BTW if there is 2 or 3 planes this is not must be considered an error (unless i am missing something).

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and GND are not the same net, so the error is correct, the Fiducial solder mask bridges items with different nets.

At least that’s how I read it.

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But allways is this. You get an aperture on the plane to the optical centering of PnP machine. I am using the kicad library for the footprint, maybe a mistake on the library with an bigger opening on mask?.

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There could be different reasons for this behaviour:

  • mask opening to big, so the mask opening really bridges copper elements from different nets. This could be improved if the mask opening in the library is reduced
  • the ERC check is not cot correct and the copper and mask are not overlapping each other. In this case this would be a bug
  • other reasons (which I don’t know)

To judge the situation a example project is needed (I don’t have the actual library versions available, so I can’t recreate even such a simple project myself).
Or you examine the project / board for yourself, and open a corresponding gitlab issue either reargding a ERC error or regarding a fiducial footprint improvement.
Until that you could simply increase the copper clearance for the fiducial pad to solve the issue for your actual board.

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Yes, the footprint is wrong. Is possible see how the plane go inside of fiducial footprint.

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This must be reported to the gitlab?

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Sure, but first you should try for others to reproduce it, mentioning your Kicad version, the name of the footprint, from which library and it would be great if you shared a minimal project showing the problem.

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I would still prefer sharing the example (minimal) project here first.

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I create a new project for the example, and works good. Seem like some on the symbol import from Kc8.
Thanks to all

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Finally i found the reason. I was place a zone cleareance 0 instead to 0.5. Even i think that keepout of fiducial must be good even if the zone cleareance is 0. But thanks to everyone.

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