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Tin whiskers: What happens when they spontaneously erupt? (2018)

microcontrollertips.com

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Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#51

Post by nomel »

MisterTea wrote: post #32
stefan_ wrote: post #25

Earlier quoted context omitted.

The Restriction of Hazardous Substances Directive (RoHS) is not about preventing garbage in landfills, and frankly it's been 18 years and the sky is not falling.

Yes but the parent is not stating that. They are stating that a "save the environment" effort is not very environmentally friendly if it makes more waste.

That assumes waste reduction is the goal, rather than lead reduction. With toxic, intelligence reducing [1], materials like lead, maybe some extra waste is a perfectly good trade off.

1. https://news.ycombinator.com/item?id=30600539

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#52

Post by ghostly_s »

robomartin wrote: post #9

I have dealt with the tin whisker problem in the context of aerospace applications (both space-borne and terrestrial flight), including extensive consulting with subject matter experts from NASA. The bottom line is quite simple: Tin whisker growth onset is a stochastic process. We cannot predict when it will start and we cannot prevent it. Once they start growing it is almost impossible to contain them. They will pok…

I did not know these whiskers had been implicated in the Toyota unintended acceleration scandal: https://nepp.nasa.gov/whisker/reference/tech_papers/2011-NAS...

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#53

Post by HPsquared »

robomartin wrote: post #24
twofornone wrote: post #21

Earlier quoted context omitted.

Are there any easy ways to clean up a PCB that's developed whiskers? And once a whisker erupts on a given PCB, does that generally indicate that others are likely to form on that board in short order?

All else being equal, once growth starts it is likely to start everywhere on that board. This is a probabilistic assumption based on the likelihood of all of the solder on that board being from the same batch and having been applied with the same process parameters. The same cannot be said of the device leads, where each manufacturer and batch could very well be different. It's quite a nightmare, particularly when yo…

Is this why space electronics often use wire-wound connections? Maybe welding the contacts together instead of soldering?

I assume for the really critical components, you'd need to avoid solder completely.

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#54

Post by zozbot234 »

adrian_b wrote: post #50
stefan_ wrote: post #25

Earlier quoted context omitted.

The Restriction of Hazardous Substances Directive (RoHS) is not about preventing garbage in landfills, and frankly it's been 18 years and the sky is not falling.

The sky is not falling in large part because the transition to lead-free solder was simultaneous with the transition to electronic devices that are not repaired and which frequently have a lifetime not much longer than their warranty time. Most current electronic devices are dumped much earlier than when they would fail due to the tin whiskers. Many consumer electronic devices made 50 years ago are still usable witho…

Consumer electronics used to break down all the time 50 years ago. Metal whiskers are not even close to being relevant when other factors impact reliability and durability to a far greater extent.

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#55

Post by stefan_ »

MisterTea wrote: post #32
stefan_ wrote: post #25

Earlier quoted context omitted.

The Restriction of Hazardous Substances Directive (RoHS) is not about preventing garbage in landfills, and frankly it's been 18 years and the sky is not falling.

Yes but the parent is not stating that. They are stating that a "save the environment" effort is not very environmentally friendly if it makes more waste.

Uhm, that is exactly the point that I'm making? That the goal was never save the environment, but rather reduce the exposure to toxic-at-any-concentration things like lead?

Hence why I quoted the program name.

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#56

Post by Steltek »

MisterTea wrote: post #32
stefan_ wrote: post #25

Earlier quoted context omitted.

The Restriction of Hazardous Substances Directive (RoHS) is not about preventing garbage in landfills, and frankly it's been 18 years and the sky is not falling.

Yes but the parent is not stating that. They are stating that a "save the environment" effort is not very environmentally friendly if it makes more waste.

Devices are disposed of (becomes waste) long before they become broken from whiskers. That makes RoHS a net-win by reducing toxic materials from landfills full of phones with broken screens and kitschy doodads with broken plastic.

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#57

Post by Animats »

adrian_b wrote: post #41
mmastrac wrote: post #37

Earlier quoted context omitted.

No known cause or solution _yet_

It is extremely unlikely to ever find any solution to the tin whiskers problem, other than alloying tin with toxic elements, i.e. either lead or antimony. The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. While replacing soldering is possible,…

The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc.

There's been some interest in laser welding for PCB assembly. But most modern components are not designed with the pins out where you can get at them with a laser beam. Laser welding is commonly used to weld the connections in automotive battery packs, so it does work.

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#59

Post by amatecha »

mcguire wrote: post #40
the-dude wrote: post #19

Earlier quoted context omitted.

Great. If we follow this line, standing next to a roll of solder is just as dangerous. No need to fire up the iron. If lead was so easily dissolved into air, wouldn't we have had massive issues in electronics factories? I don't recall ever reading such a thing ( as opposed to painters madness for example ). Not a native speaker, probably doesn't translate too well.

" Results showed that the mean PbB concentration of the exposed workers (6.12 +4.61 µg/dl) was significantly higher than that of the unexposed workers (4.63+3.91 µg/dl ) (z = 4.96; p = 0.001). There was a significant association between the blood lead concentrations with the exposure to lead (2 = 437.72; p = 0.001). " ( https://www.researchgate.net/publication/271077842_Occupatio... ) " Epidemiological and experimen…

is that because they inhaled it in fumes, or because they touched it? or something else?

Re: Tin whiskers: What happens when they spontaneously erupt? (2018)

#60

Post by ChuckMcM »

It really is an amazing phenomena. Effectively atoms of tin are moving from the tin out to the end of the whisker. We spent a week talking about whiskering(sp?) in my materials science class at USC because it was such a big deal in the EE world.

Prior to that class my world view was that only electrons could travel through metal, only to find that metal can travel through metal too!

Locally at NASA Ames they had an experiment where they had a bunch of different assemblies being exposed to various conditions (high electric fields, non-ionizing radiation, etc) and one of the things they were measuring was the production of whiskers and other changes in material properties (strength, toughness, Etc.). Always amazing what we know and what we don't know about what we know.

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