I've been trying to finish the routing on this board, but keep thinking "what if the holes need to be moved? So I decided to send off my current layout as a 2-layer board for fabrication. Since it's missing the inner two layers there are lots of vias that go nowhere, so I specified that it should not be electrically tested.
I decided to splurge and order it with the ENIG finish rather than HASL, even though it would more than double the cost of the board from $14 to $33. I want to try out the keypad and sliding switch contact patterns laid out on the back side of the board, and the only way I'll get a reasonable test is with the ENIG finish.
To facilitate this testing I decided to generate Gerber files with the vias un-tented. This means that there won't be solder mask over the vias, making them easier to access for testing. I should be able to hold ohmmeter probes in the via holes, or tack-solder wires to the vias.
If all goes well I should have the fit-test board in hand in a week or 10 days.
Experiments with the world's first microprocessor
and other electronic explorations
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