This is what can happen if you place too much trust in a (low bidder) vendor.
They may take short cuts to reduce their costs like not properly cleaning the boards after components are populated.
This is what happens to silver traces on components contaminated with solder flux after several years.
In this case the (low bidder) vendor increased the eventual final cost by about factor of 10, not including operating time lost.
We do not know if this was the vendors plan or just plain incompetance. Maybe just the vendors employees and QA department were at fault.
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