Word of advice on crystals for microcontrollers:

A company I hired into had been careless (ignorant actually) about their printed circuit boards quality and omitted their solder mask layer to cut the cost of their board fabrication. They're rationale was that their hand soldering crews would just be more careful. (ACK!)

While testing the board for temperature extremes sometimes they had a batch of strange failures that looked like software errors. The occurences were very erratic and by the time we'd drive out to see it demostrated, the problem couldn't be created. Their outsource design shop could never recreate the failure and thought the factory was crazy.

After talking to the various sides and hearing all their voodoo stories of how it occurred, I deduced that it was condensation forming on the unprotectd crystal traces and the reason the factory saw the problem was because they didn't have a controlled atmospheric environment. On high humidity days in their open air buildings, the cold test was creating the failure scenario - condensation on the traces. (In Texas the weather can change radically every few days).

The problem couldn't be recreated because the weather was changing so much and no one thought to factor it in. The design shop just thought they were crazy because they never had seen the problem in their better lab facilities.

Shortcuts on quality can extract a huge cost in labor/management.

duh