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

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

#61

Post by Ottolay »

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…

RoHS does not just restrict lead. It also restricts use of mercury, cadmium, and several toxic compounds.

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

#62

Post by zdragnar »

ChuckMcM wrote: post #60

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 e…

> that metal can travel through metal too!

I recommend watching clips of mercury amalgamations forming (nile red has some great videos on youtube).

There is something about it that is both disturbing and beautiful to me.

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

#63

Post by sydbarrett74 »

HPsquared wrote: post #53
robomartin wrote: post #24

Earlier quoted context omitted.

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.

Unfortunately, all consumer electronics companies have this fetish for making products ever smaller and thinner. It dovetails with their profit motive: make things less reliable so we all have to buy more frequently.

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

#64

Post by adrian_b »

zozbot234 wrote: post #54
adrian_b wrote: post #50

Earlier quoted context omitted.

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.

Consumer electronics used to break down all the time, but in almost all cases that was due to manufacturing defects, which were much more frequent, because many operations that are now automated were still done manually then.

The consumer devices which survived infant mortality, because they were free of manufacturing defects, had a negligible aging rate after that.

Modern electronic devices have far fewer initial manufacturing defects, due to automated production, but all age much quicker, due to very small component sizes, lower safety factors, surface semiconductor devices (MOS transistors) instead of bulk semiconductor devices (bipolar transistors), lead-free soldering and other similar changes in technologies.

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

#65

Post by londons_explore »

xmodem wrote: post #38
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…

Do you happen to know if tin whiskers have anything to do with passing current? (in other words, will a device that's in constant use develop them faster than a physically identical device that's switched off and in storage)

Passing current means thermal cycling...

And thermal cycling definitely accelerates whisker formation.

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

#66

Post by squarefoot »

zozbot234 wrote: post #54
adrian_b wrote: post #50

Earlier quoted context omitted.

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.

> Consumer electronics used to break down all the time 50 years ago

But they could be easily repaired.

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

#68

Post by dilyevsky »

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…

Miniaturization trend definitely doesn’t help here either…

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

#69

Post by alfor »

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…

Does wisker form inside semiconductor also or do they use metals immune to that?

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

#70

Post by B1FF_PSUVM »

at_a_remove wrote: post #47
xmodem wrote: post #33

Earlier quoted context omitted.

The boiling point of water is 100 °C, and yet my shower seems to produce an awful lot of steam despite not being anywhere close to that.

You have confused steam with small water droplets, akin to what emerges from an ultrasonic mister. If it were steam, you would be shrieking and then dead.

Good point. Also, steam is invisible. What we see - e.g. from a boiling kettle - is condensation.
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