Tin whiskers: What happens when they spontaneously erupt? (2018)(microcontrollertips.com)
microcontrollertips.com
Tin whiskers: What happens when they spontaneously erupt? (2018)
https://www.microcontrollertips.com/when-tin-whiskers-spontaneously-erupt-faq/
132 comments
> 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.
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.
That was a welcome rabbit hole. Thank you!
My current theory of whisker formation is single atom mercury impurities causing local mobility at the base of a whisker.
> Effectively atoms of tin are moving from the tin out to the end of the whisker.
Don't tin whiskers get built from the base up, though? So the tip was the first thing built, and just gets pushed farther away.
Don't tin whiskers get built from the base up, though? So the tip was the first thing built, and just gets pushed farther away.
State of Colorado Datacenters got them. The response to them were weird...if any machine were in any of the affected areas, they were persona non grata...they could never leave those datacenters as functional server.
It DID lever some money for an awesome off-site backup datacenter...which was eventually our only datacenter for 'reasons'.
In our case, I think one of the datacenter's raised floors got carpeted (don't judge, it predated me, I was equally baffled) and a grounding issue caused a voltage drift causing the tin to migrate...
It DID lever some money for an awesome off-site backup datacenter...which was eventually our only datacenter for 'reasons'.
In our case, I think one of the datacenter's raised floors got carpeted (don't judge, it predated me, I was equally baffled) and a grounding issue caused a voltage drift causing the tin to migrate...
raised floors in general are a nightmare for grounding/bonding/differences in potential between racks, the steel floor structure, the building, and electrical conduits.
there's a reason why almost nobody builds them new from a clean-sheet-of-paper design anymore for serious datacenter applications or ISP/telecom purposes, which are racks/cabinet on concrete slab and everything overhead now.
it's much easier to ground/bond everything together using some very fat copper cables run along ladder rack overhead, and bond all the racks to that.
there's a reason why almost nobody builds them new from a clean-sheet-of-paper design anymore for serious datacenter applications or ISP/telecom purposes, which are racks/cabinet on concrete slab and everything overhead now.
it's much easier to ground/bond everything together using some very fat copper cables run along ladder rack overhead, and bond all the racks to that.
Raised floors where a great way to create laminar flow for clean rooms. I suspect that as with manufacturing, the "clean" space is inside the computers now.
This is very surprising to me. I had no idea that certain conductors had some kind of (stochastic, according to robomartin) built-in time delayed short circuit mechanism that will, without question, manifest itself given enough time.
Like some kind of natural electronics prank.
Like some kind of natural electronics prank.
If you were feeling particularly cynical, you might wonder whether this phenomenon has been incorporated into shipping products, such manufacturers would be assured that their goods would fail shortly after the warranty expired.
> assured that their goods would fail shortly after the warranty expired
I have seen a number of similar comments on this thread. Manufacturers were dragged kicking and screaming --they were forced, through legislation-- to switch to lead-free solder. Nobody --nobody-- in manufacturing wanted this. This idea that going lead-free was a conspiracy by manufacturers to have their products fail more often is completely false.
One of the most well-known episodes of mass failures due to tin whiskers happened when the Swatch Group (watch manufacturer) converted to lead-free solder. They had so many failures that they ended-up requesting an exception from RoHS [0].
As I said in another comment. The problem with RoHS as it pertains to tin whisker failures is that we will likely never know what percentage of failing consumer, commercial and industrial products end-up in the landfill because of the forced and premature transition to this lead-free solder. If one studies that history of the transition it is easy to see it includes many companies clamoring for years of additional studies before making the change. We went into it by force in 2006 without having had full data on potential issues.
At the time I was manufacturing expensive FPGA-based real time image processing boards. I made the decision to stop shipping product to Europe.
My decision was based on a very simple reality: I still had to honor a years-long warranty in Europe and could not include any clause stating that we could not be responsible for a government-mandated technology known to have serious problems that could lead to failures at any time, even very early on. Companies were forced through mandate and given absolutely no immunity from the very real tin whisker problem. I did not ship a product into Europe for two or three years. We were busy enough everywhere else, so I did not care one bit. We actually had European customers who needed the hardware buy through a US-based path and then hand carry into the EU through whatever means. Not my problem.
[0] https://hlinstruments.com/RoHS_articles/A-1018_Swatch.pdf
I have seen a number of similar comments on this thread. Manufacturers were dragged kicking and screaming --they were forced, through legislation-- to switch to lead-free solder. Nobody --nobody-- in manufacturing wanted this. This idea that going lead-free was a conspiracy by manufacturers to have their products fail more often is completely false.
One of the most well-known episodes of mass failures due to tin whiskers happened when the Swatch Group (watch manufacturer) converted to lead-free solder. They had so many failures that they ended-up requesting an exception from RoHS [0].
As I said in another comment. The problem with RoHS as it pertains to tin whisker failures is that we will likely never know what percentage of failing consumer, commercial and industrial products end-up in the landfill because of the forced and premature transition to this lead-free solder. If one studies that history of the transition it is easy to see it includes many companies clamoring for years of additional studies before making the change. We went into it by force in 2006 without having had full data on potential issues.
At the time I was manufacturing expensive FPGA-based real time image processing boards. I made the decision to stop shipping product to Europe.
My decision was based on a very simple reality: I still had to honor a years-long warranty in Europe and could not include any clause stating that we could not be responsible for a government-mandated technology known to have serious problems that could lead to failures at any time, even very early on. Companies were forced through mandate and given absolutely no immunity from the very real tin whisker problem. I did not ship a product into Europe for two or three years. We were busy enough everywhere else, so I did not care one bit. We actually had European customers who needed the hardware buy through a US-based path and then hand carry into the EU through whatever means. Not my problem.
[0] https://hlinstruments.com/RoHS_articles/A-1018_Swatch.pdf
Much more info here:
https://nepp.nasa.gov/whisker/
https://nepp.nasa.gov/whisker/
After seeing the articles on ice spikes, I wonder if this is somehow a related phenomenon.
Remind me more of this, only in slow-mo: https://www.nature.com/articles/nature.2015.16771
Indeed. Maybe they are also related to bone spurs!
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 poke through conformal coatings such as parylene and arathane. If they don't, they will buckle (coil-up) under the coating.
While buckling sounds like a desirable outcome, this could lead to shorting of adjacent contacts in todays fine pitch integrated circuits and components.
Growth rate can be in the order of 10 mm per year. This means that adjacent leads of something as mundane as a SOIC-16 package can be shorted by a tin whisker in 28 days or less.
The take away is: There's nothing we can do about tin whiskers that is 100% guaranteed to prevent growth or slow it down by a non-trivial amount. The only path that prevents their growth is to use lead-based solder. This is why, as an example, we would do such things as send out BGA's with RoHS compliant solder balls to be re-balled with leaded solder.
Time for a bit of a rant: All my work in this area led me to look at the RoHS initiative as yet another example of something that, while well intentioned, it will likely have precisely the opposite effect from what was intended.
The fact that lead-free solder is susceptible to tin whisker growth means that 100% of all consumer electronic products are ticking time bombs when it comes to failures. This means that all kinds of consumer, commercial and industrial electronic products will fail over time in ways we might not be able to explain. The reason for this is that nobody does deep forensics when products fail. There is no reporting from the likes of Apple, Samsung, LG, Visio, Sony and myriad other manufacturers on failure rates and causes. In fact, they might not even have this data as consumer, commercial and industrial users simply replace the devices as they fail and move on.
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.
There was a bit of a movement to roll back RoHS around the time it was being enacted. Going up against many nations and politicians using "save the planet" to get elected proved impossible for those who rightly brought-up that the transition to lead-free solder required far more research before we fully understood the potential consequences.
It wasn't about not wanting to go lead-free, it was about making the move when the science and math indicated that it would not create the massive problem we now likely have on our hands. The data on electronics waste due to tin whiskers is probably impossible to find. It might not even exist. Which is a tragedy.
If you want to learn more about this, here are a couple of good links:
https://nepp.nasa.gov/whisker./background/index.htm
https://nepp.nasa.gov/whisker/reference/tech_papers/kadesch2...
https://www.google.com/search?q=tin+whisker&hl=en&tbm=isch
https://web.calce.umd.edu/tin-whiskers/
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 poke through conformal coatings such as parylene and arathane. If they don't, they will buckle (coil-up) under the coating.
While buckling sounds like a desirable outcome, this could lead to shorting of adjacent contacts in todays fine pitch integrated circuits and components.
Growth rate can be in the order of 10 mm per year. This means that adjacent leads of something as mundane as a SOIC-16 package can be shorted by a tin whisker in 28 days or less.
The take away is: There's nothing we can do about tin whiskers that is 100% guaranteed to prevent growth or slow it down by a non-trivial amount. The only path that prevents their growth is to use lead-based solder. This is why, as an example, we would do such things as send out BGA's with RoHS compliant solder balls to be re-balled with leaded solder.
Time for a bit of a rant: All my work in this area led me to look at the RoHS initiative as yet another example of something that, while well intentioned, it will likely have precisely the opposite effect from what was intended.
The fact that lead-free solder is susceptible to tin whisker growth means that 100% of all consumer electronic products are ticking time bombs when it comes to failures. This means that all kinds of consumer, commercial and industrial electronic products will fail over time in ways we might not be able to explain. The reason for this is that nobody does deep forensics when products fail. There is no reporting from the likes of Apple, Samsung, LG, Visio, Sony and myriad other manufacturers on failure rates and causes. In fact, they might not even have this data as consumer, commercial and industrial users simply replace the devices as they fail and move on.
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.
There was a bit of a movement to roll back RoHS around the time it was being enacted. Going up against many nations and politicians using "save the planet" to get elected proved impossible for those who rightly brought-up that the transition to lead-free solder required far more research before we fully understood the potential consequences.
It wasn't about not wanting to go lead-free, it was about making the move when the science and math indicated that it would not create the massive problem we now likely have on our hands. The data on electronics waste due to tin whiskers is probably impossible to find. It might not even exist. Which is a tragedy.
If you want to learn more about this, here are a couple of good links:
https://nepp.nasa.gov/whisker./background/index.htm
https://nepp.nasa.gov/whisker/reference/tech_papers/kadesch2...
https://www.google.com/search?q=tin+whisker&hl=en&tbm=isch
https://web.calce.umd.edu/tin-whiskers/
> 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.
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.
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...
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.
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.
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.
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.
They used to break down and they could and were repaired. Nowadays if something breaks it goes in the garbage can. I had an extension cable which died staying in the basement for a year. When i opened it to check the reason i was shocked. It looked like a spider net made of dust but this was metal.
> Consumer electronics used to break down all the time 50 years ago
But they could be easily repaired.
But they could be easily repaired.
My mid-1980s digital alarm clock came with a full schematic. Can you imagine that today?
Actually, yes I could imagine that quite easily. Just buy "hackable" products which do that as a matter of course. A digital multi-purpose device with an alarm-clock form factor would not even be especially complicated to make.
That stuff is really cool, but this was a bottom-of-the-shelf model from K-Mart.
Of course nowadays something that simple could be a chip the size of a rice grain, power included. So that's something :)
Of course nowadays something that simple could be a chip the size of a rice grain, power included. So that's something :)
Once things started going to multi-layer PCBs it was the end of reparability. It’s too bad because I have fond memories of fixing broken components on PC hardware and game consoles, even as someone who’s not an expert and simply a hobbyist.
> Once things started going to multi-layer PCBs it was the end of reparability.
Very true, however having full documentation would help nonetheless. My water heater electronic board cost over €250 to replace, although it contains less than €20 parts; a preprogrammed uC makes it impossible to replicate it. If it had public hardware and firmware documentation, someone could repurpose a similar but cheaper board or replicate the functions using a different rugged enough uC board, which would also likely bring down the retail price of the original spare part.
Very true, however having full documentation would help nonetheless. My water heater electronic board cost over €250 to replace, although it contains less than €20 parts; a preprogrammed uC makes it impossible to replicate it. If it had public hardware and firmware documentation, someone could repurpose a similar but cheaper board or replicate the functions using a different rugged enough uC board, which would also likely bring down the retail price of the original spare part.
My understanding is that the new manufacturing techniques stop many people but usually not skilled technicians. It's component serialization, keeping schematics secret, and exclusive supply chains that are the real problem.
"Consumer electronics used to break down all the time 50 years ago"
Citation required
Citation required
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.
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.
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
1. https://news.ycombinator.com/item?id=30600539
Last i checked tin was not an edible material. There is a small difference between having tin dust, which you cannot contain, and having electronics containing lead which you can colect and store in a warehouse ( asuming you want to address the problem in the first place).
Are you saying that electronics devices continuously let out tin dust so we end up breathing in this stuff?
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, ...).
Tin whiskers continue to grow even after you device is in the landfill. You basically have a dust of tin which goes into landfil.
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.
Hence why I quoted the program name.
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.
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)
> will a device that's in constant use develop them faster than a physically identical device that's switched off and in storage
Storage was one of the areas I researched extensively. It was like that scene in the movie "Clear and Present Danger" [0] in that the answer was always the same frustrating one regardless of conditions:
Stochastic growth onset; 0 to 3 years; can't predict growth start or rate; can't stop them; they will penetrate almost anything practical you can put on a board.
[0] https://www.youtube.com/watch?v=PqtjbWJPIgQ
Storage was one of the areas I researched extensively. It was like that scene in the movie "Clear and Present Danger" [0] in that the answer was always the same frustrating one regardless of conditions:
Stochastic growth onset; 0 to 3 years; can't predict growth start or rate; can't stop them; they will penetrate almost anything practical you can put on a board.
[0] https://www.youtube.com/watch?v=PqtjbWJPIgQ
Passing current means thermal cycling...
And thermal cycling definitely accelerates whisker formation.
And thermal cycling definitely accelerates whisker formation.
Yes. Voltage has a big effect on whiskers.
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 you are trying to figure out if this stuff can kill people you want to send into space. The only real mitigation is lead-based solder and coatings on components.
Cleaning? That can be both dangerous and highly ineffective. The whiskers are very strong due to their molecular scale. Mechanical brushing might fracture longer whiskers. Then you have the problem of ensuring that they don't go under devices or in-between contacts. The process would likely have to be repeated many times and include both manual and automated optical inspection as well as x-ray imaging (which might not be able to detect fine whiskers). And then there's the reality that you probably don't want to inhale these things at all.
So, off to the landfill we go. It is likely better to build a new board than to try to clean one. I can't even begin to compute the delta in carbon footprint between making a board with lead-based solder that will last decades and the "clean/green" RoHS board that is sure to end-up in a landfill (cleaning/fixing it is bound to have a massively larger carbon footprint that making a new board).
It's quite a nightmare, particularly when you are trying to figure out if this stuff can kill people you want to send into space. The only real mitigation is lead-based solder and coatings on components.
Cleaning? That can be both dangerous and highly ineffective. The whiskers are very strong due to their molecular scale. Mechanical brushing might fracture longer whiskers. Then you have the problem of ensuring that they don't go under devices or in-between contacts. The process would likely have to be repeated many times and include both manual and automated optical inspection as well as x-ray imaging (which might not be able to detect fine whiskers). And then there's the reality that you probably don't want to inhale these things at all.
So, off to the landfill we go. It is likely better to build a new board than to try to clean one. I can't even begin to compute the delta in carbon footprint between making a board with lead-based solder that will last decades and the "clean/green" RoHS board that is sure to end-up in a landfill (cleaning/fixing it is bound to have a massively larger carbon footprint that making a new board).
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.
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.
Well actually, there is a way, but you might kill said PCB.
Heat everything up in an oven, the solder will reflow, and you might temporarily fix the board. It’s a similar idea to the Towel/Xbox 360 fix. I can attest to having successfully saved lots of random electronics this way.
All of this started with the eco-friendly alternatives to lead solder, I have a lot of old computer hardware and motherboards, and the hardware from the early 2000s is the least reliable, whereas most game consoles, motherboards, etc. from the 80s and 90s works flawlessly. To this day I swear by the leaded stuff for personal use, it flows better, doesn’t crack, and is superior in every way.
Heat everything up in an oven, the solder will reflow, and you might temporarily fix the board. It’s a similar idea to the Towel/Xbox 360 fix. I can attest to having successfully saved lots of random electronics this way.
All of this started with the eco-friendly alternatives to lead solder, I have a lot of old computer hardware and motherboards, and the hardware from the early 2000s is the least reliable, whereas most game consoles, motherboards, etc. from the 80s and 90s works flawlessly. To this day I swear by the leaded stuff for personal use, it flows better, doesn’t crack, and is superior in every way.
Miniaturization trend definitely doesn’t help here either…
RoHS does not just restrict lead. It also restricts use of mercury, cadmium, and several toxic compounds.
Does wisker form inside semiconductor also or do they use metals immune to that?
Yes they do but slower. In the past gold was used for wires from terminal to pads. Gold as far as i know is not so subceptible to form whiskers. But gold is expensive and now they use copper instead of gold.
Unfortunately, gold is also susceptible: https://nepp.nasa.gov/whisker/other_whisker/gold/index.htm
[deleted]
Could potting prevent this, or can the whiskers "push through" epoxy?
Yes; satellite boards tend to have conformal coatings, it helps but it's not a complete solution. (The coatings also help avoid shorts from junk floating around, and launch vibration.) Because of the inherent unreliability and difficulty in replacement, they also try really hard to avoid lead-free solder requirements.
Yes? In my experience (some spacecraft electronics stuff) this is also on the list of things where we think conformal coating/potting helps prevent tin whiskers. But there are still instances where Tin whiskers have grown and pushed through conformal coating on a PCB.
Edit: Go look at the more detailed response from robomartin
Edit: Go look at the more detailed response from robomartin
No. Can't prevent it. Yes, they can push through epoxy or buckle under it (which isn't a solution). Read my longer answer for details. These things are a nightmare.
Does anybody from Germany know where I can still buy leaded solder? Unfortunately I forgot to order a lifetime supply while it was still available
It's trivial to find online shops selling it, even if the large hobby-electronics suppliers have generally stopped stocking it. RS, TME, eleshop, ... all have it.
When did that happen? I bought a spool just over a year ago and the sales person didn't bat an eye. This was in The Netherlands, if we don't have the same law then maybe there's your answer?
Is every package coming into Germany screened for Lead? Could you not just order some from another country?
> Does anybody from Germany know where I can still buy leaded solder?
I ordered on ebay, sold by a vendor from another EU country that cares less about the regulations.
I ordered on ebay, sold by a vendor from another EU country that cares less about the regulations.
Use lead solder, like NASA does: easier to use, and no whisker issues. Just wash your hands afterwards
On the contrary, I am not NASA. I'm not even a consumer electronics company. I'm a hobbyist at home, soldering things at my desk or table. Lead-free is the least of my problems when building something and I don't believe "just wash your hands" is sufficient for cleaning my workspace (or kitchen table?) of possible lead contamination.
It definitely is enough. I don't know where the myth that looking at lead kills you started, but unless you are eating it or breathing it in (soldering is not hot enough to vaporize lead) there's nothing to worry about.
>I don't know where the myth that looking at lead kills you started
For a large subset of western society it's highly fashionable to give a lot of shits about health and safety. I'm not saying this is a bad thing to care about but let's be honest here, when you treat abstract concepts like a minor religious deity there's some baggage that comes with that. Let the feedback loops run their course for a decade or three and combine that with the fact that it's very easy to be scared of things you're not familiar with and you get the current situation. This is why people go crazy over a long forgotten package of asbestos shingles sitting on some shelf in the maintenance department's storeroom or think you're gonna get black lung from using an antique coal stove a couple times a year. Their belief system tells them to go crazy and they don't have the experience to know they don't need to.
For a large subset of western society it's highly fashionable to give a lot of shits about health and safety. I'm not saying this is a bad thing to care about but let's be honest here, when you treat abstract concepts like a minor religious deity there's some baggage that comes with that. Let the feedback loops run their course for a decade or three and combine that with the fact that it's very easy to be scared of things you're not familiar with and you get the current situation. This is why people go crazy over a long forgotten package of asbestos shingles sitting on some shelf in the maintenance department's storeroom or think you're gonna get black lung from using an antique coal stove a couple times a year. Their belief system tells them to go crazy and they don't have the experience to know they don't need to.
Fellow hobbyist here. Actually your biggest health risk is industrial asthma from flux fumes. I know professionals who have spent a good fraction of there lives soldering with no lead poisoning issues. Lead needs to be consumed or inhaled for it to be an issue. The guy I meet who did have lead poisoning, large bore rifle shooting coach, from spending to much time at the “wrong end” of the rifle range. Lots of lead dust there.
I wouldn't recommend this. If you do use lead soldering, make sure you don't breathe in any fumes.
The vapor pressure of lead at 300 °C is around 10^-6 Pa. In laymans' terms, there is zero evaporation of lead happening during soldering. Ice at -40°C evaporates (sublimates) 10 million times faster.
The fumes from soldering are from the flux or rosin, and that is just as dangerous if you are using lead free solder. Always use adequate ventilation and/or filtration to avoid inhaling fumes.
The fumes from soldering are from the flux or rosin, and that is just as dangerous if you are using lead free solder. Always use adequate ventilation and/or filtration to avoid inhaling fumes.
Or just get your blood lead level measured.
A few months ago, I happened to be at the doctor getting some other stuff checked out, and the week prior to the appointment I had done a ton of soldering, like two 12-hour days bashing out a whole batch of boards, both paste reflow and hand-PTH work, with a fair bit of sucker rework, and of course after that the lab needed a good tidying so I emptied all the suckers and tip cleaners as part of that. All tin-lead solder.
Zero gloves, and I only wore a mask part of the first day (when there were other people around). And actually the several weeks leading up to that also saw a lot of SMT rework and other up-to-by-elbows-in-solder sort of activity.
So I figured, that's kind of a worst-case for my lead exposure, hey Doc, can I get my blood lead level checked? Sure why not, it's one extra vial on top of the bloodwork already being ordered!
And the results came back below the test's detectable level.
So as far as I'm concerned, if that didn't do it, I don't think I have anything to worry about. Now, I'm sort of a germophobe and I never eat with my hands, so this doesn't necessarily generalize, but as far as skin absorption or vapor inhalation, I've gone from "not very worried" to "abjectly unconcerned" after getting that result.
I would encourage everyone to get their level measured and have actual data to make decisions with. Superstition does not become us.
A few months ago, I happened to be at the doctor getting some other stuff checked out, and the week prior to the appointment I had done a ton of soldering, like two 12-hour days bashing out a whole batch of boards, both paste reflow and hand-PTH work, with a fair bit of sucker rework, and of course after that the lab needed a good tidying so I emptied all the suckers and tip cleaners as part of that. All tin-lead solder.
Zero gloves, and I only wore a mask part of the first day (when there were other people around). And actually the several weeks leading up to that also saw a lot of SMT rework and other up-to-by-elbows-in-solder sort of activity.
So I figured, that's kind of a worst-case for my lead exposure, hey Doc, can I get my blood lead level checked? Sure why not, it's one extra vial on top of the bloodwork already being ordered!
And the results came back below the test's detectable level.
So as far as I'm concerned, if that didn't do it, I don't think I have anything to worry about. Now, I'm sort of a germophobe and I never eat with my hands, so this doesn't necessarily generalize, but as far as skin absorption or vapor inhalation, I've gone from "not very worried" to "abjectly unconcerned" after getting that result.
I would encourage everyone to get their level measured and have actual data to make decisions with. Superstition does not become us.
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.
But it's still water, and it's still moving up and about of its own accord in the local air which is the point. That it isn't technically steam doesn't disprove the point the person you're responding to is trying to make…
The commenter's point isn't that the lead has technically been boiled, it's that, if we analogize to "steam" in a shower, I don't have to reach water's boiling point before I'm breathing in water. Does that translate to lead: i.e., even if I'm below lead's boiling point, could I be nonetheless breathing in lead vapor, or something like that? (I don't know the answer here, which would push me towards lead-free solder. I.e., I don't know if the precautions I'd take with lead would actually suffice.)
The commenter's point isn't that the lead has technically been boiled, it's that, if we analogize to "steam" in a shower, I don't have to reach water's boiling point before I'm breathing in water. Does that translate to lead: i.e., even if I'm below lead's boiling point, could I be nonetheless breathing in lead vapor, or something like that? (I don't know the answer here, which would push me towards lead-free solder. I.e., I don't know if the precautions I'd take with lead would actually suffice.)
That's the reason I was being persnickety and "science-y" about terms: analogies can lead you astray. You don't know the answer here, and so your options are: 1) do some experiments, 2) reason by science, not analogy.
I have some weightlifting plates. Pure iron. Can I forego iron in my diet and just ... sit next to them? Now, by analogy, sure. Practically? Probably not.
Here's one for you: what do you think happens if you drank a glass of pure liquid mercury?
Most people think you'd die on the spot. Wrong! That mercury hasn't sublimated into mercury vapor. Instead, it barrels through your alimentary canal like a shot and was used to treat constipation, of all things. It is poorly absorbed by digestion and just runs right through you.
Phase changes matter for these things.
I have some weightlifting plates. Pure iron. Can I forego iron in my diet and just ... sit next to them? Now, by analogy, sure. Practically? Probably not.
Here's one for you: what do you think happens if you drank a glass of pure liquid mercury?
Most people think you'd die on the spot. Wrong! That mercury hasn't sublimated into mercury vapor. Instead, it barrels through your alimentary canal like a shot and was used to treat constipation, of all things. It is poorly absorbed by digestion and just runs right through you.
Phase changes matter for these things.
No, soldering doesn't send streams of liquid solder through the air. And if an occasional drip of solder does splash, it is so heavy, and has so much surface tension, that it doesn't go far and doesn't stay in the air like water droplets do.
I thought everyone did the experiment of leaving a saucer of water out and seeing it evaporates over time, despite being significantly lower than 100c.
And "Steam" is wooly term for high enough density of water vapor that you see condensation - often caused by higher temperatures in the majority of cases people experience it in day to day life. So it doesn't really have a precise definition. At what temperature point does "mist" become "steam?" What %age of the volume of air needs to be water vapor? If you lowered the pressure water "boils" at a lower temperature - is that still steam?
And "Steam" is wooly term for high enough density of water vapor that you see condensation - often caused by higher temperatures in the majority of cases people experience it in day to day life. So it doesn't really have a precise definition. At what temperature point does "mist" become "steam?" What %age of the volume of air needs to be water vapor? If you lowered the pressure water "boils" at a lower temperature - is that still steam?
That first question, it is 100C at STP. Second question, enough to make you have a second or third degree burn. Third question, yes.
Good point. Also, steam is invisible. What we see - e.g. from a boiling kettle - is condensation.
We solder at 200°, which is 1500° below the boiling point and 23% of it. You shower at probably 40°, which is 60° below the boiling point and 84% of it. Because vapor pressure is typically an exponential function of temperature the absolute difference (1500°) is the more important measure here. If you were showering at -1500° you would have a point, but absolute zero is only -273.15°, so you can't.
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That by itself does not imply fumes cannot form at lower temperatures.
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.
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 experimental studies indicate that chronic exposure resulting in blood lead levels (BLL) as low as 10 µg/dL in adults are associated with impaired kidney function, high blood pressure, nervous system and neurobehavioral effects, cognitive dysfunction later in life, and subtle cognitive effects attributed to prenatal exposure. Pregnant women need to be especially concerned with reducing BLL since this can have serious impact on the developing fetus." (https://www.osha.gov/lead/health-effects)
"Epidemiological and experimental studies indicate that chronic exposure resulting in blood lead levels (BLL) as low as 10 µg/dL in adults are associated with impaired kidney function, high blood pressure, nervous system and neurobehavioral effects, cognitive dysfunction later in life, and subtle cognitive effects attributed to prenatal exposure. Pregnant women need to be especially concerned with reducing BLL since this can have serious impact on the developing fetus." (https://www.osha.gov/lead/health-effects)
is that because they inhaled it in fumes, or because they touched it? or something else?
Or you could just look at the actual material property that matters, which I believe is called vapor pressure.
Mad Hatter[0] is a good example in English.
[0]: https://en.wikipedia.org/wiki/Erethism
[0]: https://en.wikipedia.org/wiki/Erethism
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.
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.
Agreed. This, not lead fumes, is the real danger of leaded solder. You can't hand solder reliably without cleaning the iron, but both of the common cleaning techniques (damp sponge and brass wool) inevitably break the soldier into tiny balls, which bounce and roll all over the place. They can get caught in clothes, and from there they might end up getting into food. With the safe dose for lead being zero, I don't think it's worth the risk.
During my elementary school years (beginning of 198x USSR) the lead was a go to material for a lot of things - using campfires we melted the lead out of Navy cables and batteries (from the Navy dumps), no gloves, no masks, and made a lot of things out of it - toy action figures/soldiers for example, weights and weighted hooks for fishing, bullets for DYI guns, gear for some games, etc. (I'm a drop-out from PhD. program at a top Russian Math school - didn't see money in it and thus went into programming, so i guess the few IQ points i lost due to lead (i score usually about 130) is what caused such poor judgement :)
None of those activities pose the same risks as soldering using leaded solder, for the reasons given above. You are unlikely to end up ingesting significant quantities of the lead.
It's probably worth emphasizing that this is risk with home soldering, where you're likely to eat and solder in relatively close proximity, and without being completely rigorous about changing your clothes and vacuuming up every last spec of dust.
Lead free solder works fine, so there is really no reason to take even a small risk if you are soldering as a hobbyist.
(And yeah, it's probably a small risk. By all means use leaded solder if you think the slight additional convenience outweighs the small risk of significant lead exposure.)
It's probably worth emphasizing that this is risk with home soldering, where you're likely to eat and solder in relatively close proximity, and without being completely rigorous about changing your clothes and vacuuming up every last spec of dust.
Lead free solder works fine, so there is really no reason to take even a small risk if you are soldering as a hobbyist.
(And yeah, it's probably a small risk. By all means use leaded solder if you think the slight additional convenience outweighs the small risk of significant lead exposure.)
During 6 and 7 grade i was at electronics hobby club where beside soldering of new stuff we also did a bunch of desoldering too as the main source of electronics components where the PCBs pulled out from the pieces of missiles/torpedoes/etc at the Navy dumps. There was no any "safe handling" procedures wrt. lead. Granted though that washing hands before eating has been ingrained in me (and as far as i saw - in my friends too) from the early childhood.
Don't get me wrong - I'm not arguing about un-safety of lead. I'm just wondering how things can be different when one knows vs. when one doesn't know. Statistically speaking a bunch of people i knew though the childhood/school should have some lead damage. Many of them went to become military/Navy officers (growing on a Navy base biases your choice that way, i also did an attempt to go to military officers college). As my childhood was pretty typical for that time in USSR, I wonder what systemic effect missing few IQ points by a large number of people can have.
Don't get me wrong - I'm not arguing about un-safety of lead. I'm just wondering how things can be different when one knows vs. when one doesn't know. Statistically speaking a bunch of people i knew though the childhood/school should have some lead damage. Many of them went to become military/Navy officers (growing on a Navy base biases your choice that way, i also did an attempt to go to military officers college). As my childhood was pretty typical for that time in USSR, I wonder what systemic effect missing few IQ points by a large number of people can have.
I'm not quite sure what your point is. Of course we know that people can do lots of soldering using leaded solder and not suffer any obvious harm. It's not an enormously risky activity. It just seems pointless to take the risk when you don't have to.
Bioavailability of metallic lead is practically nil.
Eating lead is the worst case scenario when it comes to lead poisoning. Yes, your body will manage not to absorb much of the lead. But you can't seriously be suggesting that lead is safe to eat!
I'm not sure if maybe you were misinterpreting 'end up in food' in the post you're replying to. The GP isn't talking about the lead getting into the soil and then indirectly into the food supply. They're talking about the scenario where some little balls of solder are literally inside the sandwich you're eating.
I'm not sure if maybe you were misinterpreting 'end up in food' in the post you're replying to. The GP isn't talking about the lead getting into the soil and then indirectly into the food supply. They're talking about the scenario where some little balls of solder are literally inside the sandwich you're eating.
I don't know anyone who would recommend eating while working with lead solder. At some point, common sense has to come into play.
Fortunately, common sense is enough. Metallic lead simply isn't that toxic in the grand scheme of things.
Fortunately, common sense is enough. Metallic lead simply isn't that toxic in the grand scheme of things.
As has been repeatedly said, the problem is that small balls of solder can persist in your home environment, which makes it difficult to be sure that you’re not eventually eating them. For example, solder balls caught in your clothes or hair can fall off and land in food or drink that you’re preparing. It’s very difficult to quantify how likely this is to happen, but it’s not that outlandish of a possibility.
Now of course you could be really careful about changing your clothes and washing after you solder. Then again, you could also just use lead free solder, which works fine.
Now of course you could be really careful about changing your clothes and washing after you solder. Then again, you could also just use lead free solder, which works fine.
Or you could cite some reproducible statistics indicating that this actually happens in real life, in quantities that affect human health and development rather than mass-spectrometry plots.
Fact is, there was never any actual science behind the RoHS prohibition of lead solder. Not while lead-acid battery production was still permitted, certainly. The same people who thought it was a good idea to do this also thought it was a good idea to shut down all the nuclear plants in Germany because of something that happened at an unrelated facility in Japan. We're not allowed to argue with them because reasons.
Fact is, there was never any actual science behind the RoHS prohibition of lead solder. Not while lead-acid battery production was still permitted, certainly. The same people who thought it was a good idea to do this also thought it was a good idea to shut down all the nuclear plants in Germany because of something that happened at an unrelated facility in Japan. We're not allowed to argue with them because reasons.
We are not discussing the question of whether leaded solder should be banned, but the question of whether it is advisable for hobbyists to use it in a home environment. RoHS prohibitions on leaded solder have nothing to do with concerns about the safety of home soldering.
I'm not sure why you think that the absence of relevant safety data argues in favor of using leaded solder for home soldering. Surely one should err on the side of caution. I use unleaded solder myself without problems. Why then would I want to take on the additional risk of using leaded solder? It's worth noting that there is no known safe dose of lead ("there is no lower threshold to the dose-response relationship below which lead exposure is treated as safe" [1]). If you are spraying little balls of lead around your home environment, it's obvious that there is a non-zero risk of eventually ingesting some of them. People aren't doing scientific studies to prove that because it comes under the heading of the "bleedin' obvious" :)
Of course everyone can make their own decisions here. If you really want to use leaded solder then go ahead. What I don't quite understand is why some people react so strongly to the precautionary advice to use unleaded solder.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4961898/
I'm not sure why you think that the absence of relevant safety data argues in favor of using leaded solder for home soldering. Surely one should err on the side of caution. I use unleaded solder myself without problems. Why then would I want to take on the additional risk of using leaded solder? It's worth noting that there is no known safe dose of lead ("there is no lower threshold to the dose-response relationship below which lead exposure is treated as safe" [1]). If you are spraying little balls of lead around your home environment, it's obvious that there is a non-zero risk of eventually ingesting some of them. People aren't doing scientific studies to prove that because it comes under the heading of the "bleedin' obvious" :)
Of course everyone can make their own decisions here. If you really want to use leaded solder then go ahead. What I don't quite understand is why some people react so strongly to the precautionary advice to use unleaded solder.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4961898/
Better to solve these issues long-term. Lead's external costs in full product lifecycles are just too high.
Yeah, and we're not allowed to even put it in products anymore by law (RoHs, reach, etc)
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)
[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)
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.
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.
> 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.
The whiskers are not related to soldering. Of course there are some soldering issues which facilitate whiskers but that's about it. Tin is a normal plating material so you can find whiskets in places which were not soldered.
The whiskers are not related to soldering. Of course there are some soldering issues which facilitate whiskers but that's about it. Tin is a normal plating material so you can find whiskets in places which were not soldered.
The whiskers are related to tin.
The only reason for using tin is soldering. Tin is used because it is the only metal with the right melting temperature, neither too low nor too high.
When you do not use soldering, you do not need tin. While it is possible for whiskers to also form on other metals, the chances of this happening are negligible in comparison with tin.
So yes, the only reason for whiskers being a serious problem is the need to use soldering.
The only reason for using tin is soldering. Tin is used because it is the only metal with the right melting temperature, neither too low nor too high.
When you do not use soldering, you do not need tin. While it is possible for whiskers to also form on other metals, the chances of this happening are negligible in comparison with tin.
So yes, the only reason for whiskers being a serious problem is the need to use soldering.
There are tin plated connectors.
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.
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.
If you can get the parts you need in SSOP or TSSOP packaging, with the pins visible from straight down, laser brazing might work.
Brazing is done at higher temperatures than soldering, but with a laser, you can apply the heat to just the area of interest, and hopefully not cook the ICs. Laser soldering already exists, and there are laser cutters, so adapting one for laser brazing ought to be possible.
The advantage of brazing is that you can use many more materials, most of which don't contain either tin or lead. Low-cost aluminum brazing rod or wire might work. Working temp around 700C. This is going to take careful heat management. Worth a try for aerospace applications.
Brazing is done at higher temperatures than soldering, but with a laser, you can apply the heat to just the area of interest, and hopefully not cook the ICs. Laser soldering already exists, and there are laser cutters, so adapting one for laser brazing ought to be possible.
The advantage of brazing is that you can use many more materials, most of which don't contain either tin or lead. Low-cost aluminum brazing rod or wire might work. Working temp around 700C. This is going to take careful heat management. Worth a try for aerospace applications.
Low-temp aluminum brazing rod has cadmium.
Besides lead, there is a second element which greatly reduces the risk of tin whiskers, when alloyed to tin: antimony.
However the proposals of replacing the tin-lead alloys withe tin-antimony alloys have been rejected due to the fear that antimony is also toxic.
While antimony in high doses is indeed quite toxic, it is less dangerous as a pollutant than lead, because it does not have the same tendency for very long time accumulation in animal bodies and such a strong effect on the nervous system.
However the proposals of replacing the tin-lead alloys withe tin-antimony alloys have been rejected due to the fear that antimony is also toxic.
While antimony in high doses is indeed quite toxic, it is less dangerous as a pollutant than lead, because it does not have the same tendency for very long time accumulation in animal bodies and such a strong effect on the nervous system.
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> No one has been able to eliminate whiskering, as the phenomenon is not yet fully understood.
It's the kind of stuff we should be embarrassed not to understand. I get that understanding living things can be tricky due to complexity and issues with controlling conditions, but a lump of metal? Whatever we find out will at least save us money in damaged devices, and hopefully drive some progress in metallurgy as well.
We had an era in semiconductor manufacturing when despite the relative simplicity the process was not understood/controlled fully, which took the toll on yield. E.g. CMOS was super fussy due to difficulties in creating gate oxide - impurities in air like halogens made the yield seasonal [1]. But now I assume that if any problems arise, they're due to bona-fide complexity.
[1] https://news.ycombinator.com/item?id=28178612
It's the kind of stuff we should be embarrassed not to understand. I get that understanding living things can be tricky due to complexity and issues with controlling conditions, but a lump of metal? Whatever we find out will at least save us money in damaged devices, and hopefully drive some progress in metallurgy as well.
We had an era in semiconductor manufacturing when despite the relative simplicity the process was not understood/controlled fully, which took the toll on yield. E.g. CMOS was super fussy due to difficulties in creating gate oxide - impurities in air like halogens made the yield seasonal [1]. But now I assume that if any problems arise, they're due to bona-fide complexity.
[1] https://news.ycombinator.com/item?id=28178612
A lot of the challenge here AFAIK is that the process needs to be understood at the molecular level, where we measure time in picoseconds (10^-12), while this process takes something like 10^6 seconds. The disparity is an absolutely astronomical factor of 10^18.
> It's the kind of stuff we should be embarrassed not to understand.
We understand it. Onset is stochastic. Mitigation is impossible given current regulations in consumer-land. Read my longer comment for further details.
EDIT: What I mean by "we understand it" is that we know that lead-free solder chemistry leads to tin whisker growth. When I was taking a deep dive into this many years back, the researchers I was working with at NASA told me "Growth onset can be 0 days to 3 years after manufacturing. Your guess is as good as mine.". And, BTW, you can have growth start in a few days in one corner of the PCB and a few months later elsewhere. It's a complex relationship of materials properties.
We know that tin whisker growth in lead-free solder is as much of a reality as gravity is between two celestial bodies. In other words, it will happen. We simply have no way to predict when or how quickly they will grow. It might just be too complex to compute/predict given the variables involved.
We understand it. Onset is stochastic. Mitigation is impossible given current regulations in consumer-land. Read my longer comment for further details.
EDIT: What I mean by "we understand it" is that we know that lead-free solder chemistry leads to tin whisker growth. When I was taking a deep dive into this many years back, the researchers I was working with at NASA told me "Growth onset can be 0 days to 3 years after manufacturing. Your guess is as good as mine.". And, BTW, you can have growth start in a few days in one corner of the PCB and a few months later elsewhere. It's a complex relationship of materials properties.
We know that tin whisker growth in lead-free solder is as much of a reality as gravity is between two celestial bodies. In other words, it will happen. We simply have no way to predict when or how quickly they will grow. It might just be too complex to compute/predict given the variables involved.
That sounds like not understanding it.
Not quite. We understand that we can't build an anti-gravity device and don't even know how to go about thinking of one. Understanding that something is impossible (or likely impossible) is understanding. We might not like the answers (I sure didn't at the time) yet they are a based on knowledge and decades of research by some of the smartest scientists I have ever met.
There are parts of the process which we do not underestand. Testing is expensive especially at this level and nobody wants to pay for things which _could_ happen.
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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.