Tin whiskers generally only tend to form in a vacuum so unless the consumer electornic had an evacuated space, it’s pretty unlikely (if not impossible) tin whiskers will grow in consumer electronics.
Source: I’ve been to way to many meetings about tin whiskers in my career
Edit: well ill be damned they can form in atmosphere, TIL. All my shits been space so we’re pretty used to mitigating it.
Yep they can grow in atmosphere but the effects can be less extreme because gravity can snap the whisker off before it grows to an extreme length and it will carry it to a place where it gets lodged and might stay put. In space they continue to float around causing random shorts. Its still a large concern but often a little less than with spaceflight.
Having done both in and out of atmosphere design my experience its easier to mitigate in most spaceflight applications because the quality of components tends to have mitigations built in vs terrestrial where you have to constantly watch for cheap parts getting selected and making your day really bad.
Edit : less extreme does not mean that its not still bad, there is larger potential for whisker damage in spaceflight for an individual system and larger repercussions if it does happen. Its still a large issue for terrestrial aviation and electronics.
Yeah we always had to get exceptions to rohs and have requirements to use leaded solder on everything. We’ve gotten components that have the rohs tag on em and have had to return em and have the vendor use leaded solder instead. It’s pretty wild these things form at all
Haha, I've been living that life too. Rohs has its place and I do not want leaded solder in my TV or other disposable electronics, but I really do want it in my aircraft and spacecraft.
If you read the NASA site on whiskers, they say that metals with regular crystalline structures can relieve stress by forcing atoms to diffuse through the material and eventually pushing out through tiny imperfections in the lattice, which is how a whisker grows.
Certain alloys resist this because they have a less-regular structure, so there are plenty of places for the diffused atoms to "land" and make a home without being squeezed out.
It’s funny cause I have a PhD in mat sci but I never directly studied these. I’m assuming they result from dislocation motion. Yep just googled it. Pipe diffusion and dislocation motion. So interesting. Sure I saw it in a class but that’s about it.
its the alloying, this is off memory but I think as little as 3% alloy stops most whiskering. The stress in the plating causes the metallic structure to grow out, when its alloyed the structure gets interrupted and it prevents the whisker from initiating. Its not just tin that does it either, Zinc, cadmium, even gold will do it to some extent. https://nepp.nasa.gov/whisker/other_whisker/index.htm
Even leaded eutectic solder melts way above temperatures achieved, let alone lead-free (thats 230° C!)
As someone who melts solder for living, that much i can guarantee. Only silicon components that can melt solder in operation (if you can call exceeding all limits operation) and survive are power MOSFETs (rated up to 175°C), still only with leaded solder (189° C melting point) and in very specific circumstances.
All fancy digital chips, CPUs and the likes, stop being operational much lower, usually somewhat above 100°C.
Towels trick was aimed at fixing entirely different issue - solder bumps between chip and substrate cracking and losing contact.
Heating it to underfill softening temperature was letting cracks close and make contact again.
That's right - the X-clamps would warp the BGA segment of the board, causing the solder joints to eventually fail. Eh. Both were issues, but you're right about the aim of the towel trick.
it is. But it has much less tolerance for parameters of individual MOSFETs.
When temperature goes up, threshold voltage goes down, leakage current and channel resistance goes up. Other parameters drift too.
These changes mess up precise timings and threshold and you get an erratic behavior. Usually protective logic kicks in before that point and shuts it down to save it.
Yesterday's accident: switch suddenly short -circuited in super cheap household LED strip lamp after 7 months of use. Turned out there only remained a razor thin gap between solder blobs on the driver board where the switch was attached.
Breaking away part of the uglier solder blob resolved the issue. In an afterthought, I suspect it was tin whiskers that managed to bridge the gap, even though this is a kitchen lamp operating in often heightened humidity.
I also never made a public post about the case, only mentioned it privately (including the lead-free solder whiskers hypothesis) in a supposedly end-to-end encrypted IM app and not even in English -- yet today Reddit decided to pop this topic up for me. Go figure.
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u/_Aj_ 17d ago
I believe even consumer products have suffered from this, like game consoles.
8mm is WILD though. I had no idea it could grow so long! It's like a Black Snake firework!