Well, it's time for the first bad report... :-(
Received the production samples. Excellent build. In fact so much excellent that it has created a problem on it own.
In the earlier prototypes I used to work with a different PCB factory which had more limited production capacity and less precise equipment. The result of that - working prototypes. This time the new factory has equipment which is apparently much better and has managed to run soldermask between the teeth of the keyboard comb pads. Result - keyboard not working unless some other techniques are used, such as additional rubber pads, etc. The reason for that is because the soldermask is taller than the exposed copper in the pads and the panel contacts can't create the needed short in the comb. Grrr... :-(
I have fixed the PCB file now to force soldermask expansion (should have done that long time ago!), but now the big question in front of me - what to do with all those first batch manufactured systems with damn non-operation keyboard combs? Trying to think of a quick solution to patch them so people can receive them sooner. So far my ideas are circling around additional self-adhesive conductive rubber pads (tried them with success), or some sort of thin elastic conductive sheet to stick under the keyboard panel (no idea if such thing exists at all).
It is very frustrating problem that needs a quick and clever solution...