Wrong LED footprint size

Hey guys this is my first foray into Kicad. I am creating a board with a simple 10 pin female header and a 2D array of LEDs. I selected the APA102-2020 because of its small size, but when I went to arrange them in the PCB editor I noticed they were too big relative to my original mock up. As the name would suggest those LEDs are 2mm x 2mm, but they are represented as 3mm x 3mm in the pcb editor. Am I missing something dumb here? This is a fairly ubiquitous component, and it would be strange to have been accidentally mocked up at 150% of its real size.

What you’re measuring there is the pink courtyard rectangle, which includes some safety margin for production, space for the pads and so on. The actual outline of the LEDs is the smaller gray/white box on the Fab layer.

Depending on your manufacturer and the desired component density, you might want to make the courtyard area smaller, the KiCad library uses quite large conservative gaps, that most manufacturers should manage without issue.

1 Like

Thank you, this makes a lot of sense! Being as these are very small SMD components I assume I can snug the courtyard rectangle up pretty close to the margin of the pads with a little bit of wiggle room and even bring the pads in a little bit?

Yes, you probably can make the pads smaller and reduce the courtyard margin. I can’t tell you by how much, but there are IPC standards and you can also check with your manufacturer. Too small pads might make bad solder connections.

1 Like

The pads are 0.25mm bigger than the LED-body. This is according to the datasheet of the manufacturer.
Then the courtyard is 0.25mm per IPC-7351 (or 7352, it has the same value). That’s a total of 0.5mm per side, which gives you the 3mm overall increase in size.

Those are sane numbers for a ‘regular’ PCB. I have made and upstreamed this footprint and used it extensively. I personally would not feel comfortable to shrink the pads.

That does not mean you should not try to get a more dense design. For high-density designs, IPC allows smaller courtyards. The pads also could get smaller. Or find another LED. I think there are 1x1mm LEDs now with similar functionality.

1 Like

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.