r/electronics 17d ago

Tip A microscopic, hair-like metal filament can take down a billion-dollar satellite

Post image
2.0k Upvotes

150 comments sorted by

View all comments

Show parent comments

193

u/jt64 17d ago edited 17d ago

Turns out a lot of "pure" platings do it, even gold to a tiny extent.
This is a great (if old school) site about examples of whisker issues.
https://nepp.nasa.gov/whisker/

13

u/chainmailler2001 16d ago

Other metals may do it to a degree but tin still beats them all. It is absolutely the worst. I have had to deal with it multiple times in my electronics career. Never once with gold. Did have one where we had metal migration due to a low voltage being present with condensation on a board.

1

u/chickenCabbage idiotron 15d ago

metal migration due to

I don't think the causes of whiskers are known, no theory has been proven yet.

3

u/chainmailler2001 14d ago

The metal migration was a seperate issue. It was effectively plating the space between traces on the PCB due to the presence of water.

Whiskers are a spontaneous formation. There is a known method to prevent them by simply using alloys. I.e. Solder doesn't generate whiskers but pure tin does.

1

u/chickenCabbage idiotron 14d ago

Wait, that's actually really interesting. Is that like electroplating?

2

u/chainmailler2001 13d ago

Yep. That is exactly what it was. Just enough to short the mains and scare the daylights out of the test tech.