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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)

#41

Post by adrian_b »

mmastrac wrote: post #37
dmitrygr wrote: post #15

Earlier quoted context omitted.

As you read in TFA, there is no known solution, nor even a known cause for whiskers

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, any known alternative method would hugely increase the price for the assembly of electronic equipment.

Soldering is not used because it is a good method for making electrical connections, but because it is extremely cheap, allowing many thousands of connections to be made simultaneously, during a pass of a PCB through a reflow oven, or over a soldering wave.

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

#42

Post by Steltek »

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…

> In other words, it is likely RoHS has caused --or will cause-- massively more garbage in landfills. As a simple data point, my 40 year old HP-41 calculator still works perfectly fine. It is impossible to imagine a RoHS-compliant calculator not ending up in a landfill way earlier than 40 years.

Environmentalists can only wish that people were disposing of their electronics because of tin whiskers. Long lived consumer electronics needs a cultural overhaul more than it needs leaded solder.

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

#43

Post by formerly_proven »

mmastrac wrote: post #37
dmitrygr wrote: post #15

Earlier quoted context omitted.

As you read in TFA, there is no known solution, nor even a known cause for whiskers

No known cause or solution _yet_

Okay, so here's what's what. Tin whiskers have been known for ~100 years. Originally solder was just tin. Lead was added specifically in the 30s or so to avoid tin whiskers [1] though nobody knows why that works. RoHS/lead-free has been around for ~20 years and there hasn't been a definitive solution.

[1] (and because Pb63Sn37 or the inexplicably more popular Pb60Sn40 are eutectic and near-eutectic, respectively, which is nice for wire dipping and related sports)

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

#44

Post by foldr »

Flozzin wrote: post #10
dmitrygr wrote: post #4

Use lead solder, like NASA does: easier to use, and no whisker issues. Just wash your hands afterwards

I wouldn't recommend this. If you do use lead soldering, make sure you don't breathe in any fumes.

The trick is not to end up inhaling or eating the solder in its solid state. This is actually quite difficult to avoid, as cleaning the tip of your iron will create lots of tiny solder balls that fly everywhere and can persist in your environment.

Personally I would say that in hobbyist electronics tin whiskers are the least of your concerns when it comes to the reliability of the devices you’re making. I wouldn’t risk using leaded solder even if the risk is low.

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

#47

Post by at_a_remove »

xmodem wrote: post #33
the-dude wrote: post #14

Earlier quoted context omitted.

The boiling point of lead is 1749 °C (3180 °F).

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.

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

#48

Post by _Microft »

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.

They are assuming that these devices would be used long enough for tin whiskers to become a problem. I seriously doubt that RoHS will be causing more waste - because at the point that devices become unusuable, they are on in the trash anyways for completely unrelated reasons (think: bezel to large to be popular, plastic backshell instead of metal or glass, device is too thick, device is too heavy, ...).

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

#49

Post by mmastrac »

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.

Saving the environment by reducing actively, acutely hazardous materials and saving the environment via reducing landfill/carbon emissions are completely different goals.

As others have pointed out in this thread, reducing landfill waste from electronics is a much more complex problem and just adding leaded solder will not solve it.

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

#50

Post by adrian_b »

stefan_ wrote: post #25
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…

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 without any problems caused by the aging of the soldering or of the semiconductor devices (but old electrolytic capacitors may have to be replaced). The electronic devices that are made now do not have any chances of such a long lifetime, with the exception of a few devices made for special requirements, e.g. military/aerospace.

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