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.
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.
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.
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.
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)
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.
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.
> 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 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 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.
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.
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.)
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.
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?
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.
Great. If we follow this line, standing next to a roll of solder is just as dangerous. No need to fire up the iron.
If lead was so easily dissolved into air, wouldn't we have had massive issues in electronics factories? I don't recall ever reading such a thing ( as opposed to painters madness for example ). Not a native speaker, probably doesn't translate too well.
"Results showed that the mean PbB concentration of the exposed workers (6.12 +4.61 µg/dl) was significantly higher than that of the unexposed workers (4.63+3.91 µg/dl ) (z = 4.96; p = 0.001). There was a significant association between the blood lead concentrations with the exposure to lead (2 = 437.72; p = 0.001)." (https://www.researchgate.net/publication/271077842_Occupatio...)
"Epidemiological and 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 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.
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.)
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.
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.
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.
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.
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.
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.
