Electronic – Eagle CAD custom SMD pad for bushing contact

eaglesurface-mount

I want to attach a panel mount potentiometer to a PCB. But I need the bushing to be grounded. Ideally I would just make the hole for the pot thru plated but the fab does not permit really large thru plated holes. So my first attempt is two SMD pads with a thru plated hole in the middle like this:

eagle bushing contact

This obviously has issues. Can anyone recommend an alternative solution?

If not, do you think this would work if I accept all of the overlap and clearance issues with these pads? Will the hole actually be through plated so that the top and bottom pads are in fact connected?

UPDATE 1:

As suggested by Peter Bennett, a possible solution is to make a circle using the bStop layer to expose the ground plane:

eagle bStop for bushing contact

So there would be no contact on top but I think because the tin is slightly raised and soft it should make good contact with the bushing. We'll see …

Best Answer

I doubt that the potentiometer's nut will make a reliable contact with the small pad like that. To make a reliable contact, I would make the pad encircle the hole completely, and put a star washer between the pad and the nut. Alternatively, do that on the bottom layer.