Use lead solder, like NASA does: easier to use, and no whisker issues. Just wash your hands afterwards
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.
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.
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.
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.
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.
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 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.
[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)
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.
"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)
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.)
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.
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?
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.
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.
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.)
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 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.
Fortunately, common sense is enough. Metallic lead simply isn't that toxic in the grand scheme of things.
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.
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.
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.
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.