Improving Clarity of PCB Silkscreen?

[Chris56000]

Hi!

The attached picture is part of a design I recently submitted to JLC PCB for manufacturing.

The PCB was designed and laid out, initially in the free "Design Spark", later upgraded to a paid for Easy PCB Licence.

The Silkscreen Font on this is a Digitised version of the UNO Stencil Font used by "Wireless World" magazine from 1947 till mid 1968 and used by many British Consumer and T & M manufacturers during this period.

Apart from the fact that the figure "4" has ended up filled in on account of its small size, the lettering has come out perfectly!

Can any experienced PCB designer offer me a recommendation, in text height and thickness, in mil units, for these component references, so the figure "4" as used in "D4" shown alongside the 40 Way PCB header PL1 comes out a little clearer please?

I did look up JLC's Design Guidelines and they suggest 6 mil is the thinnest text width recommended – I think this lettering I did was 12 mil thickness but I can't remember what height it was without digging through all the text style definition tables again!

Chris Williams

[Feynman]

Your silkscreen is totally fine to be honest. The are always process tolerances (your IC4 has an "open" 4, for example). And as long as one can clearly read the letters, I don't see any problem.
Typical values for readable silkscreen are 1mm character width, 1mm character height and 0,18mm line width. But this depends also on font type and printing method, of course.

[Whales]

Another option sometimes worth considering: soldermask has much better resolution than the silkscreen.  I use it for graphics, the difference is amazing.  This gives you another two font surface options with different tradeoffs: bare PCB board (orange) and plated copper (bright & shiny).

[S. Petrukhin]

JLCPCB sometimes has problems with silkscreen printing, they have this section is not stable enough, it seems to me. I once received boards with smeared silkscreen printing-this was at the beginning of the year, when they were working in difficult quarantine conditions.

But pay attention to the internal number of JLCPCB - it is much smaller and 4 is not filled in there.
I think the point is the thickness of the line. Moreover, screen printing is affected by track to have the thickness and push the stencil of silkscreen.

I use the Consolas font (line width = 6 mil, height = 45mil or more) - in it, 0 looks nice, I (caps i), l (low L) and 1 are clearly distinguishable.

Why use a very small font on a large TH board with a low density? 

[S. Petrukhin]

Another option sometimes worth considering: soldermask has much better resolution than the silkscreen.  I use it for graphics, the difference is amazing.  This gives you another two font surface options with different tradeoffs: bare PCB board (orange) and plated copper (bright & shiny).

If I order boards covered with gold, then I make the inscriptions with a copper layer with an open mask. Not all, of course, only the important ones and where possible. At one of the exhibitions, I saw business cards in the form of a thin PCB with gold text - it looks bad. 

[Chris56000]

Hi!

Why use a very small font on a large TH board with a low density?

I will be going through the Text Style Tables in Easy–PC for my next design with a view to making the text height larger!

At the time I designed this, my friend requested each of the 40 pins on the  backplane plug PL1 in the PCB shown in my first post had the signal name next to it, so as the spacing of the pins is 0.1" (2.54 mm), this limited the text height to somewhere like 40% of that!

Chris Williams

[Alex Eisenhut]

Your silkscreen looks fine. If you want high end stuff, ask for LPI.