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?
As a follow-up to this, we eventually figured out that the kiosk screen cover wasn't sealed properly and cleaning solution sprayed onto the plastic was seeping into the enclosure, running down the inside of the keyboard mounting bracket, and then into the housing for the keyboard itself. The cleaning agent would corrode the copper in the vias if they weren't sealed well enough. After sealing the enclosures properly we saw much better performance out of them and far fewer failures.