Additive solder mask

Layout
1

Hello,

Is there a way to make the F./B.Mask layers additive?
i.e., filled polygons will denote the masked region and not the opening.

Thanks

2

KiCad’s solder mask layers are defined and used in a way that conforms with regular PCB manufacturing techniques, and it’s unlikely that will change anytime soon.

If you want something special, then I guess you will have to improvise. Maybe you want to apply some sort of conformal coating to a part of the PCB? You can draw some graphics on an auxiliary layer and communicate this to your PCB manufacturer. But before more guesswork, can you tell us more about what the final goal is you want to achieve?

It seems to be related to your other topic:

3

wow… that is a quick response. THANKS

You’re right, I need it for adding a coating layer.
The thing with adding a filled polygon is that I need a round ‘no-coating’ island within a coated polygon - i.e., I need to subtract the island, which is not supportedby plain graphic polygons afaik (kind of xor-ing two regions)

4

I would also suggest to use an extra layer. But as a work around you can convert your polygon to a zone and then add a cut out. It takes a bit of fiddling to get the cutout into a round shape but depending on your requirements this might be a possibility.

5

Thanks. Excellent advice.
(just wondering how to make a round cutout)

Two suggestions to the KiCad team:

  • Add an option for a round filled zones
  • Add an option for filled zones cutouts (polygon & round) - a ‘substractive’ filled zone

Thanks again.

6

There are already some items on the wishlist. Take a look around the GIT and give a thumbs up, if it seems important to you, helps the devs to set priorities :slight_smile:

7

You can already make any shape you want and then right click it and use a combination of “shape modification” and “create from selection” to get what you need. Including polygons with holes, round zones, etc.

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8

The second part is a “rule area” - check the box to “keep out zone fills”.

9

To extend on this, what I have been doing to create “arbitrary shape” zones is as follows:
Draw a track on a metal layer in the desired shape, select the whole track (u), then right-click → create from selection → create zone/polygon from selection. you can also merge multiple polygons. subtractive changes are a bit more annoying, you would have to follow the existing polygons with a track and create a new polygon. Alternatively, there is a kicad PCB to SVG extension with which you can export your project and modify it in Inkscape (Stretch extension GitHub - JarrettR/Stretch: KiCad to SVG and then back again)

10

. . and a little more: to create a simple or complex shape one can always use mechanical CAD to draw the shape, export it as DXF then import it to KiCad on the required layer.

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