"Zinc Whisker" issues?

Solution 1:

Are you asking about on ROHS circuit boards, or from zinc coatings of raised floors and rack mount equipment?

Not that it matters much... since they are thinner than a human hair, they should generally burn off before becoming a real problem. They are also large enough to be caught be even the most modest of air filters.

Within power supplies they should generally burn off before becoming a real problem. Conformal coatings help. They are primarily only a signaling hazard in more sensitive logic circuits that have no conformal coatings (not many of those around).

Most likely you just have a vendor grasping at straws to explain poor quality choices for their power supply OEM. It would be nice if you can name names and model numbers. That might bring more (and more helpful) responses.

Solution 2:

I've never had a failure I could attribute to zinc/tin whiskers, though my sample set isn't enormous and I haven't ever really had a rash of power supply failures like you describe that would make me go on a hunt for a root cause.

I'd be looking at more conventional problems (bad capacitors in the power supply or a transient electrical fault rate pretty high, especially since you say you had two "large occurrences" of PSU failures), though it sounds like you already have.

My short list in case it differs from yours/your electrician's:

Electrically: poorly stabilized power because of a wonky UPS or PDU/CDU, ground faults, etc. If your "large occurrences" were in areas served by the same power distribution equipment this becomes more likely.

Environmentally: temperature & humidity; Check inlet/outlet temperature of your equipment (especially if the failures happen in the same physical area of the datacenter: You may discover an airflow/cooling issue causing your gear to run hot).

Equipment/Manufacturer QC: check the dead power supplies for bulging/blown capacitors, especially if the failures are in units bought around the same time. Make sure you're not pushing the power supplies too hard (lots of hard drives & power-hungry CPUs may warrant a bigger PSU)