How best to model a PCB that plugs into microSD card slot?

Layout Footprints
1

I’m looking to produce a small PCB that plugs directly into a microSD card slot.

I’ve checked out dimensions (such as the last page of https://www.kingston.com/datasheets/SDCIT-specsheet-8gb-32gb_en.pdf), and think a 0.6mm board with the right shape should work fine.

I’ve found a KiCad project in GitHub that has something similiar GitHub - voltlog/emmc-wfbga153-microsd: eMMC WFBGA153 to microSD card adapter PCB that also does this, and opened it up to see how it does it.

I’m fine creating a footprint, and I’m also fine creating a board outline - what I’m not sure on is to somehow specify or encode in the footprint when it’s meant to go in a strictly shaped area of a PCB.

Looking at the linked project, on the layout I see the pads are there in the footprint, but there’s nothing to indicate or enforce that those pads are a certain distance from the edges of the specially microSD card-shaped PCB.

I kind of want to be able to make a footprint that has the profile of the microSD card within it, and to be able to enforce that PCB outline follows it exactly on three sides.

That’s to say, anyone can download this footprint, and just somehow snap their PCB outline to it, and know the outline is right, and that the pads are both correct and in the right place.

2

You could embed the important part of the board outline in the footprint:

footprint_edgecuts
footprint_edgecuts1671×967 178 KB

2 Likes
3

Perhaps this sort of thing?

ksnip_20230625-224955
ksnip_20230625-224955713×758 24.1 KB

This footprint was in the Kicad library. It has the card outline as part of the footprint. I added the text on the F.Silk.

1 Like
4

Thanks - that’s interesting. I just went and loaded that exact one in KiCad, and it appears the inner perimeter is F. Silkscreen, and the outer is F. Courtyard. But neither of those would become part of the edge of the board (when placed in the layout) automatically outline I think?

5

Ah… I see. I didn’t realise if you simply chose to draw in the edge cuts layer of the footprint, it would automatically become part of the overall PCB outline when placed. I’ll give it a go, thanks!

1 Like
6

You may draw a silk on the courtyard, or most anywhere else if you wish. I wouldn’t draw an edge cuts on top of another layer as DRC might complain, but you could place edge cuts up against a silk or courtyard without problems.

7

Here’s my old YouTube video on doing this - things have changed but, the concept is still valid… (click the ‘Show more’ in the video info…)

1 Like
8

Thanks. Yes it seems as @mf_ibfeew says you can now just draw the edge cuts in the footprint editor, which is exactly as I wanted.

1 Like
9

kicad is a very useful forum! :+1:

1 Like
10

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