Electronics > PCB/EDA/CAD

JLCPCB smallest possible label and text font size

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Krotow:
Did somebody recently tried to order PCBs with label and text size below 1mm in JLCPCB? Which text size is smallest that they reluctantly accept and which is still distinguishable? I'm asking because minimum text size/height in JLCPCB is 1mm, but I would like to make label text 0.75mm high due to space constraints.

tooki:
Even 1mm text often comes out illegible, depending on the font. The silkscreen on low-volume [edit: 2-layer] PCBs at JLCPCB is often done with UV inkjet*, and the resolution isn’t that high, I suspect under 300dpi. I don’t think 0.75mm text height stands a snowball’s chance in hell of being legible. Even on a high-res true silkscreen that would be asking a lot.

If you can, make your label on the copper layer. The resolution of the copper layers is far higher than of the silkscreen layer. If you can’t do that, can you do it on the solder mask layer? That’s still better resolution than the silkscreen layer.


*inkjet printer using UV-cured lacquer/resin inks

scottapotamas:
I've been reliably using 0.8mm high, 0.8mm wide characters with JLC >=4 layer processes without legibility issues. The rare time I've used 2L processes has shown lower fidelity.

I typically aim for 0.15mm linewidth for non-text geometry (markings or other callouts) and it's generally fine but can sometimes show minor inconsistencies for short lengths.

Krotow:
Seems I should put some smaller text somewhere on PCB and see what will happen :)

Kean:
I regularly use 0.8mm high silkscreen designator, and using 8% ratio (height to line thickness), but that is really a bit low.  Like scottapotamas these are mostly 4 layer designs which generally JLC build with better quality silkscreening.  So I maybe would not recommend going to 0.8mm on their low cost 2 layer process if the text must be legible.  I've probably done it, so I could dig around to see if I have any samples to check for quality.

Because the 8% ratio that I've been using is so low, I strongly suspect that the PCB houses increase the line thickness to meet their requirements.  It hasn't occurred to me how thin that actually is, and the end result has generally been quite readable to me.  On reviewing some of the production PCBs from our CM (who isn't using JLC), I can see the silkscreen text is a slightly lighter weight but still readable. Again, I suspect they have standard automated process with rules to adjust these.  They've never highlighted it to me.

If I want the text to stand out but still be small (e.g. a connector or button label), I've increased the ratio from 8% to 15% - but unlike the CAD view on the PC screen, I cannot actually see much difference between them on the actual PCBs when using 0.8mm high text.  It is noticeable with larger text.

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