What if silkscreen info is running "over" copper islands?

Hi,

It’s the first time I’m preparing a PCB for a board house (most probably, OSH Park, not sure yet…) and I’m wondering what happens if silkscreen stuff is running “over” copper islands of components.

First off: is this allowed? Or is this an issue? What is best practice here?

You can find an example screenshot I’ve taken from a PCB I’m currently making here: kicad PCB snapshot

For instance, if you take the text “Q17”, then all is fine, since that text is not running over the copper island of component Q17.
However, if you take text “R72”, for instance, then you see that part of the text is running over one of the copper islands of component R72. And that is my question: is it allowed? Can it do harm during the PCB fabrication or afterwards when manually soldering the board?

–Geert

The silkscreen will not be printed on the exposed copper. This is automatically removed by the software used in the board house.

I have had the same experience as @andete. It won’t adhere to the copper properly AFAIK. If you run it through a gerber checker like the one at 4pcb.com (owned by Advanced Circuits, another good board house), it will throw errors about this as well. I recommend you take care of these issues before you send out your files.

I recommend you take care of these issues before you send out your files.

I will, I will… since the PCB’s themselves are quite big (28cm by 11cm), I do not want to have a problem during (and after) fabrication, It would be a “costly” mistake… :wink:

I’ll check the 4pcb.com board house today and see what it gives…

There’s an option that controls this in the “Plot” dialog used to generate Gerber files. If you select the option “Subtract soldermask from silkscreen” anywhere there’s a hole in the soldermask (i.e. over a pad) then the silk screen will be clipped so it does not cover exposed copper.

This option is really handy for dealing with silk screen lines and graphics as well.

Take a look at the silk screen layer gerber file with this option selected and unselected to get an idea of what it does.

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It’s the first time I’m preparing a PCB for a board house (most probably, OSH Park, not sure yet…) and I’m wondering what happens if silkscreen stuff is running “over” copper islands of components.

If you’re going through OSH Park, our fabs will fix this automatically. Still doesn’t hurt to check the box Nathan mentioned, since it produces the exact same result.

For other fabs, you’d probably want to check, but I’d reckon they fix this automatically as well. Some tools (notably Eagle) don’t have a good way to trim silkscreen that goes over mask, so the fabs run the risk of shipping lots of useless boards if they don’t handle it on their end.

I just tried out the “Nathan”-solution and that works great. Shows exactly which parts of the silk screen are going to be removed.

Great feedback, guys, tnx!!!

Sorry for reviving this thread, but is there a opposite option to "Subtract soldermask from silkscreen”? When I want to “Subtract silkscreen from soldermask”. I have a polygon in mask which I want to have as exposed copper, except the places where there will be silkscreen, making sure there is correct mask content so the silkscreen will not go over naked copper (and in the end removed at fabrication).

Please take this to a new thread.