[sdiy] Substitute for pin matrixes?

[John Mahoney]

(Pardon my top-posting.)

Good analysis, IMO. I managed to overlook the fact that the 
ball-bearings are steel, and thus compatible with magnets.

I figured the plated vias would be adjacent to the split pads, as you 
say in (2).

John

P.S. No, Karl, I'm not stuck on the use of magnets, but they attract 
my attention. (Sue me for the puns.)


At 09:07 AM 1/25/2010, Jerry Gray-Eskue wrote:

>The only tricky thing to this scheme is the split pad with plated through
>holes, The problem is the through hole plating will short the split pad.
>I see two possible solutions.
>
>(1) set up the split pad as a standard plated through hole and after receipt
>of the fabricated board cut a slot on each side at the split point clearing
>the plated through short. - at additional fab cost you may be able to get a
>board house to do the post slot cuts.
>(2) use a secondary via to connect to the bottom side and specify the split
>pads as non plated through.
>
>Of these the plated through version would make a more reliable connection as
>the ball will only touch the very edge of the hole.
>Additionally if you use light weight balls you may be able to use a flat
>sheet of magnetic material on the bottom side of the board with magnetic
>balls to keep them in place and provide some additional contact pressure.
>
>An additional consideration would be using silver plating for the best
>connection (lowest resistance), or gold plating for the best oxidation
>resistance and
>reasonably low resistance.
>
>- Jerry