I'm fiddling with a tiny PCB layout (to avoid some other chores) and trying to decide if I want component silkscreens, outlines and ref designators. They would have to be 50 mils high, preferred only 40.
What's the smallest silk that anyone has done successfully?
I'll verify with our PCB vendors tomorrow.
Most device name I do with 0.8 mm high font and a linewidth of 0.16 mm. There are readable.
I often do 40 mil character height, 10 mil width. Parts that are crammed, get 38 - 8, or 37 - 7 Comes out fine on the PCB, could go down more.
Last design, skipped 40 - 10, except some ICs.
I haven't been that brave yet. But I have done boards without any part designators, or only the ICs, etc. Forces users to have a parts-location drawing handy.
Many of my boards use 0805 parts and have expanded footprints to make hand assembly easier. For this case, space taken for part designators isn't bad. But with 0603 parts it begins to get unreasonable. And for smaller sizes, forget it!
I've seen high-volume boards with parts-designator info around the edges, tightly packed and lined up with the part-location order. That works well. Often you really need parts immediately adjacent, removing the designators to the edge can help.
Yikes, that's 32 mils in American units! I felt brave considering 45.
I like 0805s usually, but this board is about as big as a postage stamp (a little less, actually) and is 0603s and some microscopic EPC fets.
The EPC parts are hard to place and hard to rework, and fragile, so I'm putting them on what I hope is a common sub-assembly that we can make in quantity. It becomes a component for a bigger board. If a GaN fet fails, we'll just replace the entire baby board.
It will be a mouse-bite thing like this
but will have a lot of parts.
My manufacturing people like ref desigs, but they'd need to be really small.
mandag den 11. februar 2019 kl. 00.52.54 UTC+1 skrev John Larkin:
this guy show some examples made by OSH Park
0.6mm with 0.18mm stroke is what I usually use these days on tight boards, more like 1mm with 0.2mm stroke on less tight boards. Usually comes out okay. 40 mils is about 1mm, of course. I think you should be fine.
--Spehro Pefhany
26 mil font height/4 mil stroke width, with the default Altium stroke font.
This was for a quick prototype board ordered off SeeedStudio, and the designators came back perfectly readable.
? David
Did 25 mil height, 4 mil linewidth with fab Eagle Electronics, came out just legible (if you don't mind that it's that small; poor eyes need a magnifier for sure).
I don't think even the cheap Chinese proto fabs have a problem with 30/6 mil text.
I have 30/6 set as default.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:
my Digi-Key ruler has legible 20mil writing.
4 mil vector graphics seem to be rather reliable.
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