We purchased a number of stainless steel kiosk keyboards from a Chinese manufacturer a while back and have been seeing extraordinary failure rates (around 30%). Groups of keys just stop working. I've pulled several of them apart and traced the problem to plated through-holes / vias that have failed. I've been repairing them by passing a small wire through the hole and soldering it directly to the trace or pad on either side. Photos show what they look like when I pull them apart:
Given this information I have two questions:
What's up with these? Any theories on why they're failing? Anything we can do to prevent it?
Is the repair method I mentioned earlier appropriate? Is there a better way or anything specific I should be taking into consideration?