I noticed that the built-in libraries don’t have outlines for small components, like 0402. It’s just the two pads. I’m used to seeing a silkscreen outline (like the courtyard) - is there a reason these are left off the default footprints? Seems this would get incredibly confusing on a compact PCB.
(Sure, I can add them, but I didn’t know if there was a clever way to “convert courtyard to silkscreen” or something)
(Kicad 5.1.6)
I don’t know exactly why they don’t have the silkscreen marks, but I can give a probable reason.
KiCad footprints must be as generic as possible to be manufacturable by even less capable manufacturers. Silksceen has registration error and low resolution. Adding the short lines, like there are in 0603 resistor footprint, to 0402 wouldn’t be very reliable. On the other hand adding a courtyard with wider margin wouldn’t serve most needs well because 0402 may often be used in tight designs assembled with machines. In the designs I have made 0402 footprint courtyards have usually overlapped and using courtyards in the silkscreen would have been a mess.
The KiCad Library Convention says that the silkscreen outlines should be just outside the physical edge of the component so that it can be seen when the part has been populated, but not much farther away. Again, the KiCad library must be as generic and all-purpose as possible while still keeping good quality.
Personally I have added the silksceen marks to 0402 and accepted poor but mostly readable quality. You should modify your own footprints for your own needs, creating your own libraries, possibly based on the KiCad libraries - that’s the recommended way to use the KiCad library anyways when it doesn’t meet your needs directly.
There’s no any really simple way to duplicate the courtyard to the silkscreen in KiCad’s footprint editor. Copy/paste or duplicate the graphic lines and change the layer of each of them from their Properties. Or just draw new lines directly in the silkscreen layer. After all, you have do this only once for each different component.
Incidentally, 5.1.7 SMD resistors have silk down to 0402.
For 0201 and 01005 the reasons @eelik gave apply.
Thanks. I’ve never had an issue with the quality footprint silkscreen from any (cheap) supplier, down to 5 mil width on 0402 parts. I suppose if they are really badly registered the silkscreen can get onto the pads, but I’ve never seen that happen. 0402 is as small as most humans will go for hand-stuffing, so it makes sense that smaller parts don’t have silkscreen.
I figured there must be a good reason to avoid it on 0402, seems like it’s just a little excessive caution. I’m glad this is fixed in 5.1.7 though.
I certainly could modify my own library, but it’s a bit tedious to do so. Not a huge deal.
I’m just guessing here. but really small SMT components are usually reserved for really dense boards. On those dense boards there is no room for silkscreen.
Also:
The KiCad Library Team tries real hard to follow existing conventions and common sense.
And how much effort is it to add a few silkscreen lines to your own custom library for 0402 and 0201 and maybe smaller Footprints? Maybe 10 footprints, half an hour work?
But still, this is duplication of effort. Maybe it’s useful enough to have 2 sets of libraries for these components? With and without silkscreen?
On the other hand, removing some silk screen items from items from an existing library is easier and quicker then adding them.
On a side note:
Have you seen some of the video’s from “The Rossman Group”. He’s a guy who lives in New York, makes utube vids about apple products, rants about them, and sometimes also repairs them. He uses “Boardview” software to find components. (Which is based on data from probably reverse-engineerd apple products). And in KiCad you can do sort of the same.
You click on a component on a schematic, and it’s highlighted in Pcbnew. No reason to go hunting for R325 all over a densely populated double sided board.
Some schematic symbols already have datasheet links embedded to somewhere on the 'net, but I prefer to put all datasheets for IC’s I use on my own PC, and (sometimes) also make links to them directly on the schematic symbols.
Quite nice for repair work. You have the schematic & PCB open, and have very quick access to Schematic, Footprint locations on the PCB, test points and datasheets.
You could even argue that software like this makes silkscreen obsolete.
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