I was happy to find in 7.0 libraries a plethora of copper only symbols (KiCAD, OSHW).
To my surprise, these symbols are only drawn on the copper layer, and there is nothing on the solder mask. As a result, the 3D viewer shows them covered by solder mask (see image below)
This is not what I want, and I suspect that this is not what the majority of users out there expect. I had to edit the footprint to copy the symbol to the solder mask layer, and now I get what I expected to begin with:
Those logo’s (In the Symbol library) are available both in Silkscreen and in Copper. I do not know what the “majority” of KiCad users would like best, but they are just graphics, and therefore they exist on only one layer.
If you want them to exist on multiple layers, you can turn them into pads. You can do this with:
Load your logo (the copper layer version) in the footprint editor.
Put a small SMT pad on top of the graphics.
Press [Ctrl + e] to enter the pad edit mode.
Select the graphics too.
Press [Ctrl + e] again to exit pad edit mode.
This has added the graphics to the pad, and now it can be manipulated as any pad, so you can turn on / off layers, make it a part of a net, etc. There is a limitation though. All parts of a pad must be connected, so you would have to do this with each letter of the text.
So that looks like a bit of low hanging fruit to experiment a bit converting graphics and making a pull request to update the KiCad libraries with some updated logo’s.
Thank you such a detailed answer. Very much appreciated!
It seems like the approach I followed is about as time consuming as your proposal, and it does not have the limitation of needing to be connected. Just to document it for my future self or others:
Window-select all graphic elements and text
[Ctrl + d] to duplicate, then Enter to leave the duplicate in place.
For each separate element (graphic or letter) hit e to edit the polygon properties
In the drop down menu, pick F.Mask
The time consuming part is that I had to do this once for the main symbol, plus once for each and every letter in “Open Source Hardware”. But the result seems very good.
Do you think there is any value in submitting a pull request for the existing Copper Symbols? Aren’t those symbols intended to be exposed copper, without solder mask?
No, I think they’re intended to be the way they are, with soldermask. Copper shapes with mask on top are fairly common when you want a nice and subtle marking on a board.
Having said that, I suspect no one would object if you wanted to open a merge request for additional versions without mask, as those are nice too when you want something a bit less subtle
In my opinion there is little sense in using the same graphic at cooper and solder mask. If you want your graphic be gold than you need it only at solder mask having continuous zone under it. If you want green graphic then you need that graphic only at copper.
No probably not. Making new footprints from the cleaner vector SVG may be worth it, but it’s just reducing the number of coordinates in the logo’s a bit.
Also, I just thought that if you want exposed (tinned or ENIG?) copper, then you can just insert the logo twice at the same location, and move one of them to the solder mask layer.
Oh, if there was a simple way to do that, that would be ideal. The only way I found to do it is by modifying the footprint. Do you know how to “move a copper footprint to the solder mask layer” without having to edit the footprint?
Indeed, as far as I know you have to do that in the footprint editor, but you can do all graphics at the same time, and when you are in the footprint editor, you might as well make a copy of the graphics and move that copy to another layer.
You do not have to do each letter separately. You can make a selection (or a copy) and then use: Footprint Editor / Edit / Edit Text and Graphic Properties, combined with the Only include selected items filter.
But considering the whole picture. My usual method is to put the logo’s on the Silk screen, as I do not have enough unused copper to put those logos, and I think this is probably the most often used method.
Here we have circular copper area under logo shaped mask opening at left. Copper + identical mask opening in the middle. Copper + identical mask opening, surrounded by a zone, at right.
In my opinion the mask opening which is placed on a solid copper area is the easiest one, and having a shaped copper under the mask doesn’t give any benefit. The rightmost one gives a certain kind of special effect but it’s not as clear as the other options. The middle one may suffer from mask registration error unless the copper is a bit larger, and if it is larger, there’s still some kind of thin frame.
Wow, thanks for the detailed answers and the different approaches to achieve the “exposed copper” look. I also now understand why one would use masked copper symbols for a subtle marking on a board.
