Add a proposal for exposing the front-side pads on the back side

[obra]

As mentioned on Twitter, I'd get value out of being able to use this same connector for pogo-pin programming. This PR is a proposal for how we might expose the front-side pads to the back side of the device footprint. If this looks good, I'd be happy to modify the other device footprints accordingly.

[obra]

It'd look something like this:

[erichVK5]

I have no preference for or against this sort of modification, but it might be good to get the vias aligned along the longitudinal axis of each pad, and an equal distance from the board edge, to make it easier for a pogo pin fixture to be designed such that the "underside" pogo pins can "key" into the vias.

Erich.

[obra]

I agree -- (The horrible vias aren't part of the footprint, just the hack of a board mockup)

[nitz]

I think this is a fantastic idea, even as an optional bit. It's a rather elegant (and attractive, imo) way to add bed-of-nails-able support while still adding only minimal surface area.

Also along the lines of what @erichVK5 said: I know your vias there were just to quickly mock it up, but the in-pad vias aligned nicely in the centers of the pads may actually be something interesting visually. It adds to the instant recognizability, while also being functional. (I do feel like I've seen some board houses complain about regular vias on pads, but perhaps I'm misremembering that.)