I Want Copper to Copper DRC errors for unconnected copper polygons

Software
1

Hi All, and big thanks to all contributors,

I have been working on a software which uses generative AI to automate the creation of business cards

The software accepts a handful of text fields and outputs some image files and these image files I run through more software to turn into .kicad_pcb files and then more software turns them into a .zip archive of gerbers

I have sent my designs to PCBWay and to Elecrow and I have found that Elecrow results in a higher quality product so I have sent all my recent tests to them

A few times my designs get rejected by them for DRC and I have been trying to automate the DRC process myself so I can catch the errors before sending them to Elecrow

The KiBot and KiAuto projects have been a huge win for me and I use them via Docker:

https://github.com/INTI-CMNB/KiBot
https://github.com/INTI-CMNB/KiAuto

This issue / question I am writing here now I first asked on the KiAuto repo here:

https://github.com/INTI-CMNB/KiAuto/issues/36

The maintainer understood exactly what I was trying to do and suggested I ask here on the forum

The specific KiCad program in question is pcbnew_do and my github issue has all relevant details and additionally I have links to KiCad project files which can be used to reproduce the issue

At the heart of this question is the title:

I Want Copper to Copper DRC errors for unconnected copper polygons

AKA my software is producing hundreds / thousands of unconnected copper polygons and I want to run a DRC step which reports if any polygons are within X mm of each other

I plan to publish the full source for this software once the DRC is working as I want

I dont want Elecrow to be flooded with gerbers which fail their DRC

Thanks!

2

Not sure I understand fully what the issue is . . . my assumption is that you are making a standard type business car (Name, Phone, email, maybe a logo, etc) from think PCB.

My question is, why do you care if there are DRC errors ? why does this cause you an issue ? can’t you simply tell your fabricator to ignore them ?

If you must do this how is DRC to know what should and should not be connected ? after all you don’t have a schematic to tell it . . .

3

Thanks for writing back

The business cards have the standard text which you are describing and the characters of the text are never too close to each other to cause Elecrow to complain

The business cards also have background images and I use something like a form of “stippling” to provide a gradient / shade / brightness to the image but the image is just the exposed copper layer so its always gold (Immersion Gold) or silver (HASL Lead Free) and the detail in these background images is the issue

can’t you simply tell your fabricator to ignore them ?

My impression when they wrote to me was that they cannot ignore them and I could be wrong but it did make sense to me that basically I was asking them to manufacture a design with XYZ ~“resolution”~ and their machines of course have limits on what they can do and what can be safely done

If you must do this how is DRC to know what should and should not be connected ?

I understand DRC rules usually deal with “connections” etc but DRC is also just short for Design Rule Checking and the rule I have I want to check for is not about connections but about the spacing between copper polygons.

From what you understand of the PCB manufacture process do you think when Elecrow tells me “this failed some of our DRC” I can write back “please make this anyways” and they will allow the order to continue?

When they wrote me I believe they mentioned minimum trace width specifically e.g. 0.15mm

Thanks again for your attention towards this,

4

I think yes, but I have never ordered anything at Elecrow.
They could even not seen your PCBs. Just run their DRC and got some Errors. For example clearance between adjacent polygons is 0.05mm while their minimum is for example 0.1mm.
This means risk that something you planned to be isolated during fabrication can be shorted (because clearance is too small). If you don’t care if such small distance can be (by not enough precise technology) reduced to 0 than you probably can just tell them to ignore Errors.

5

Hi! Thanks also for replying

I will send in some more test orders this week or this weekend at the latest and see if they will agree to ignore the errors / warnings. I will also have to wait for the orders to build and ship to me so I can say the result is close enough to the spec / preview my software renders.

If all goes well I can accept that when sharing my software I tell users to tell the board shop to ignore errors / warnings but I would like to know is what I am asking for with automated DRC close to possible or maybe already possible with KiCad?

I have chosen the parameters of my business card drawing software such that none of the shapes should be <= 0.15mm in diameter and also <= 0.15mm in spacing between each other but even with these edits I am being told by the board shop / Elecrow that their DRC says error / warning the traces or trace spacing are too small

So I really would like to have a DRC feature I can run on my designs after my software renders them so I can see that KiCad DRC agrees or disagrees that I have correct minimum width and minimum spacing - this is all to help me have better conversation with Elecrow so they dont feel like I’m wasting their time going back and forth about what may be their software complaint about these specialized / custom designs I am sending them

Thanks all,

6

They probably don’t realize that it’s just “art.”
Tell them to make the design as-is, and you will accept any boards that don’t etch completely, or over-etch.