Teaching Soldering to kids: use leaded or lead-free solder? - Page 1
Forum section: electronics / beginners

author: jimjam
author_rank: Regular Contributor
timestamp: June 21, 2023, 01:37:17 am
content: I'm going to teach my kid (6yo) and his friends (6-9yo) soldering. Should I use leaded (60/40) or lead free solder with them? My wife and also the other parents are paranoid about the kids working with lead solder which lead me (pardon the pun) to order a spool of lead-free solder. I am not used to working with lead-free solder, but I'll be playing with it first to familiarise myself.

author: ataradov
author_rank: Super Contributor
timestamp: June 21, 2023, 01:48:06 am
content: Use lead free. Not even for health reasons. It is not that bad and they will not see the difference.I'd be more concerned with proper fume evacuation. This is far greater danger that is present with any solder.

author: ZigmundRat
author_rank: Regular Contributor
timestamp: June 21, 2023, 02:15:35 am
content: Given the already reported paranoia, I’d suggest go the lead free route. Use a fume extractor, proper flux and temperatures and it should be a fine exercise. They would need to learn to use lead free anyway. I would suggest a SnCuNiGe (Sn100C type) alloy or SAC307 for easiest use. They perform a lot like Pb and are eutectic.

author: EEVblog
author_rank: Unknown
timestamp: June 21, 2023, 02:16:50 am
content: Lead free. It's the standard these days.As someone else said, fumes are more the problem, not the lead.

author: jimjam
author_rank: Regular Contributor
timestamp: June 21, 2023, 02:26:19 am
content: Quote from: ZigmundRat on June 21, 2023, 02:15:35 amHow are those compared to the SnAgCu that I've already got now?

author: EPAIII
author_rank: Super Contributor
timestamp: June 21, 2023, 05:04:24 am
content: I have been using lead based solder for over 65 years. I guess I am dead from it.By all means, use the lead free so thegreat unwashedwill be happy.

author: ataradov
author_rank: Super Contributor
timestamp: June 21, 2023, 05:19:54 am
content: Quote from: EPAIII on June 21, 2023, 05:04:24 amWell, this reply indicates that there may have been some damage done.Nobody says you will be dead, but why voluntarily works with potentially hazardous materials when there are better equivalents? It is some sort of EE macho thing?

author: Zero999
author_rank: Super Contributor
timestamp: June 21, 2023, 08:18:01 am
content: From a safety point of view lead solder is better, because it doesn't produce such nasty fumes as lead-free, which has a stronger flux.On the other hand, lead-free is used in industry now, so it's not a bad idea to get him used to it.

author: Zero999
author_rank: Super Contributor
timestamp: June 21, 2023, 10:30:35 am
content: Quote from: ataradov on June 21, 2023, 05:19:54 amLead free solder was introduced due to environmental concerns, not the health of those working with it. Solid metalic lead is inert and doesn't get into the blood easily. Even if a child eats some, not much will be absorbed, with most passing through their digestive system unabsorbed. The boiling point of lead is so high, too little evapourates during soldering, to pose a health risk from inhalationIt's soluble lead salts which are easily absorbed and pose the geatest risk to health.The main hazards from soldering are the fumes, which are worse with unleaded solders and burns.

author: artag
author_rank: Super Contributor
timestamp: June 21, 2023, 10:46:40 am
content: The compulsion for using lead-free solders is in manufacturing. It should not apply to repair (where you should use the same type as used initially) or protoyping, which is rarely regulated, though some administrations may misapply it.Unfortunately moral panic and lazy thinking may mean that only lead-free with it's more dangerous fluxes is actually made available. So it's probably best to learn how to use it safely (higher temperatures, better ventilation).

author: agehall
author_rank: Frequent Contributor
timestamp: June 21, 2023, 10:52:32 am
content: I’d be more concerned with the kids burning themselves than anything related to lead or fumes tbh. Fumes are of course not healthy for you, but I doubt they will be soldering enough to have any serious health consequences from them.

author: tooki
author_rank: Super Contributor
timestamp: June 22, 2023, 06:49:13 pm
content: Quote from: jimjam on June 21, 2023, 02:26:19 amSN100C is nicer than SnAgCu.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 22, 2023, 07:14:36 pm
content: Been using SAC305 for a while now - never had any issues and produces nice shiney fillets. Not sure why you would teach kids to use something that is rarely used, and will most likely continue the decline in use.

author: SmallCog
author_rank: Frequent Contributor
timestamp: June 22, 2023, 10:17:45 pm
content: If you were teaching them in anticipation of going into industry (eg in an educational setting) then definitely teach lead free it's probably what they'll be using.If on the other hand you're teaching them for the sake of a bit of general knowledge, then consider the use of leaded solder. Used correctly leaded solder is safe, so you could use this as a chance to teach them how to handle chemicals and substances properly.It does however sound like you've already made up your mind though.I will re-iterate to be careful of fumes. It's not that the fumes are somehow safe because there's no lead in the solder.

author: Infraviolet
author_rank: Super Contributor
timestamp: June 22, 2023, 10:27:55 pm
content: Things may have changed since a long time ago when I last tried lead-free solder, and resolved never to again, but lead-free solder always had a reputation for being trickier to work with and therefore a less satisfying experience to learn as with lead-free one was going to spend longer struggling to train ones-self in how to make the solder go where you wanted it to. With leaded you could do adequate joints within minutes of first picking up an iron. Things may have improved since, or it may just have been the lead-free I was using was a bad brand.Leaded is definitely nicer to work with, but annoyingly lead's health risks, though small for soldering, are certainly higher for younger people still going through nervous system development than for grown adults.

author: ataradov
author_rank: Super Contributor
timestamp: June 22, 2023, 10:49:37 pm
content: Modern lead free solder is virtually indistinguishable from the leaded. You really need to have prior experience with both to tell the difference. I doubt an untrained eye would notice. And the molten behavior is also very close.

author: radiolistener
author_rank: Super Contributor
timestamp: June 23, 2023, 01:24:09 am
content: If you're worried about your health, you can use lead free. If you're worried about soldering reliability, then use lead soldering. For better results and better corrosion-resist you can also try silver solder.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 23, 2023, 03:28:08 am
content: Use lead free. For two reasons. 1. The social one. You will never convince the various moms that anything else is OK. It is not a battle worth fighting. 2. Whatever small risk there is from leaded solder is multiple times greater for children. They absorb it more quickly and suffer measurable effects at significantly lower doses. And are more likely to exhibit higher risk behaviors such as licking hands clean and the like.I personally believe that all of the metals toxicity situations are over blown, but that doesn't change the fact that there is a single very clear answer to your question.

author: EPAIII
author_rank: Super Contributor
timestamp: June 23, 2023, 06:30:31 am
content: Nothing macho. Just a fact.And I do not have an EE degree, just a lifetime of electronic work. My degree is in physics. I do claim the title "engineer" from years of work in electronics and systems design and numerous job titles bestowed on me by others.As for lead, yes there are documented dangers. But, to the best of my knowledge no one has documented any problems with the occasional use of leaded solder. There are substances, even elements that are far more dangerous than lead. And yet we use them on a daily basis. We even have them on our breakfast and dinner tables. They are present on every table of many restaurants. We use them in many foods. And they are always present inside our bodies. Others are used around the house on a daily basis. We use them for cleaning and to kill germs. We would be much worse off if we did not use them. Yet I would not recommend ingesting them.It is not just a matter of a chemical being dangerous. It is also a matter of just how that danger is generated. How the chemical is used.Quote from: ataradov on June 21, 2023, 05:19:54 am

author: radiolistener
author_rank: Super Contributor
timestamp: June 23, 2023, 09:08:00 am
content: if you're planning to use it for mass production, you're needs to use lead free solder. Not because it is very dangerous, but because overseers require it. If you don't do it, you will be punished. As for your private usage, you're free to use lead solder.Just don't use it for electronics mass production, because such electronics lifetime should be short. There is exception for medical and military electronics, where reliability and lifetime should be good enough, so lead solder still allowed to produce medical devices and military equipment, but it requires a lot of certifications.Regarding to lead toxicity, yes such issue exists, but it is not so scary as some people telling. You're already got a much more dose from tetraethyllead which was used in gasoline for a very long time from 1920 and still used in some countries. It's concentration is still very high all around the Earth since 1920, despite the fact that many countries already stopped to use it in fuel.

author: RoGeorge
author_rank: Super Contributor
timestamp: June 23, 2023, 09:17:21 am
content: Teach them soldering with lead-free, because lead-free is what the electronics industry is using now.

author: radiolistener
author_rank: Super Contributor
timestamp: June 23, 2023, 09:29:22 am
content: Quote from: RoGeorge on June 23, 2023, 09:17:21 amyes, if they planning to work in mass production electronics industry they needs to learn on how to deal with lead free solder, because it's a little bit more hard than using lead solder.

author: janoc
author_rank: Super Contributor
timestamp: June 23, 2023, 09:40:42 am
content: We are using both leaded and lead-free without issues.Far more important is to explain to the kids that they should not put the solder in their mouth, eat or drink while working and that they should wash hands after they are done. And that applies regardless of whether or not you use leaded or lead-free solder - there is plenty of nasty stuff on the boards and around that warrants proper hygiene and safety precautions, e.g. not "shooting" a snipped off component lead into someone's eye or getting burned on the iron. The type of solder is really the least of your problems here.Re proper fume extractors - yeah, if you have them. Setting up 20 workspaces for a workshop with fume extractors (and not just the cheap fans with "filters" blowing the smoke around) is not so trivial. We have to make do with ventilation (good for also other reasons) and technique.

author: Zero999
author_rank: Super Contributor
timestamp: June 23, 2023, 10:21:39 am
content: Quote from: CatalinaWOW on June 23, 2023, 03:28:08 amIt's true children are more vulnerable to heavy metal poisoning, but the same is true of the fumes, which are worse in lead-free solder.I do agree about using lead free, but it's because it's what they'll be use in industry, if they decide to do it when they grow up, rather than safety.

author: wizard69
author_rank: Super Contributor
timestamp: June 23, 2023, 02:21:00 pm
content: I'm going to take the minority report here and say go with leaded solder. Why?Because one goal when working with children should be to teach safety. That includes the handling of chemicals and metals, along with regular PPE (safety glasses). In this case handling of all solders, leaded or not, should be followed up with cleaning of ones hands.As for lead the fear of lead is ridiculous if the child is old enough to understand that you don't ingest the material.

author: Bud
author_rank: Super Contributor
timestamp: June 23, 2023, 03:02:10 pm
content: Burns from accidentally touching molten solder or the soldering iron will be more severe for lead-free because of higher tempetature.As kids we routinely melted lead out of car batteries and made things out of it.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 23, 2023, 06:32:27 pm
content: Why do all these theads descend into people who think that leaded solder was restricted to protect the health of humans, and others pointing out that the benefit of leaded solder is pretty narrow now as to not be worth it. It rarely goes anywhere, just "wellIused this because of this" (I'm aware I'm guilty of this very line).I fail to see any benefit of teaching children to solder with leaded solder. And frankly if you think you should use leaded solder to "teach children to wash their hands" then I'm not sure they're ready for being anywhere near a soldering iron.It's 2023, yes in some instances leaded solder is easier to use, but if you struggle to use any decent lead free solder - then you should probably evaulate your setup and temperatures. The days of poor joint quality, or embrittlement are long gone.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 23, 2023, 06:34:08 pm
content: Quote from: Bud on June 23, 2023, 03:02:10 pmWait, a 20C difference.... at 190+ makes itmoredangerous? Accidently touching any kind of melted solder is going to be bad.

author: wizard69
author_rank: Super Contributor
timestamp: June 23, 2023, 08:34:58 pm
content: lead in various forms, such as in gasoline is vary dangerous. Likewise lead in paint can result in significant damage to young children that ingest it. However lead in a bar of solder in a shop/lab is not anywhere near as dangerous.As for young kids Yes you have to explaining to them the danger associated with anything on the work bench. Common work bench materials such as glues, contact cleaners, flux removers and other goodies that haunt our labs can have a far more significant & immediate impact on a child's health. Frankly I'm not sure I'd want a 5-6 year old anywhere near common shops, but that is something for a parent to judge. I'm just not sure a child of that age has the ability to really grasp warnings and instructions.

author: ataradov
author_rank: Super Contributor
timestamp: June 23, 2023, 10:52:03 pm
content: But it is not even the question of dangerous or not, or degree to which it is dangerous. It is simply not necessary to use leaded solder, it adds nothing. People that say lead-free solder is bad most likely tried it over 10 years ago, when it was crap. It is not anymore, modern formulations behave just as well when soldering.Robustness may be different, but who cares in this case. You are not launching satellites. It is just kids learning to solder.

author: xrunner
author_rank: Super Contributor
timestamp: June 23, 2023, 10:57:55 pm
content: Quote from: ataradov on June 23, 2023, 10:52:03 pmI've been reading along. Well I'm always open to changing my opinon ataradov. So in that regard I'm going to order some and try lead free solder again. I'll get some SRA Products SAC305.

author: pickle9000
author_rank: Super Contributor
timestamp: June 23, 2023, 11:16:43 pm
content: Lead free, I only use leaded when repairing old equipment. Practice practice practice.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: June 24, 2023, 12:00:30 am
content: Lead free. When one of the parents hears some child is being exposed to "toxic lead fumes in the classroom" this will likely to set off an hysteria shit storm - on their WhatsApp clique. You can account for the inexperience of children, but not the ignorance of their parents.+ I use leaded.

author: janoc
author_rank: Super Contributor
timestamp: June 25, 2023, 01:39:06 pm
content: Quote from: AndyBeez on June 24, 2023, 12:00:30 amDepends on parents. We have never had issue with this - but then the parents who want their kids to take part see first-hand what that workshop looks like and that there are maybe fumes, things get hot, there is potentially dangerous machinery around (e.g. we have a laser cutter in an adjacent room) etc. It is theirinformedchoice and responsibility to decide whether or not their kid takes part. If they don't like what they see they are free to leave.We had a much bigger screaming match when a couple thought that they are entitled to have their kid participate in the workshop with them watching even though they weren't vaccinated against covid. This was during the time where covid restrictions to allow access only to people with a vaccination pass (e.g. in restaurants and other places) as an alternative to a full blown lockdown were common in Germany and there was a published rule ("hygiene concept") at the club that only vaccinated people have access (along with wearing masks, etc.). Yet some people still thought (and think) that the rules apply to everyone else but not to them. They were told their kid can take part but they will have to remain outside and come pick them up later. Finally they left when they realized that their screaming and threats with lawyers and what not won't impress anyone.But then this is Germany and people coming with their kids to hackspaces/makerspaces tend to be generally the more sensible/reasonable kind, understanding that it is a workspace/workshop and not a daycare. And that there is a certain amount of their own responsibility called for.

author: liaifat85
author_rank: Regular Contributor
timestamp: June 25, 2023, 06:25:04 pm
content: Of course, lead-free solder is the safer option. They are still children.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 25, 2023, 07:01:41 pm
content: If you have the choice, obviously leaded solder, due to following reasons:* Health reasons. Lead-free solders tend to have more dangerous fluxes (and this is the only real threat model; the metal itself is a red herring).* Melts at lower temperature, making working with ground planes etc. significantly easier without having to pre-heat boards or set the soldering irons at uncomfortably high temperatures* For the same reason, prolongs tip life* By being eutectic mixture, sets quickly, reducing risk of improper (cold) joint if the pieces move during soldering* Surface look indicates better if the joint succeeded or not. Lead-free always looks a bit kinda like a cold joint, even if it's not. Making distinction between cold joint and proper joint is important for beginners. One can later increase the level of challenge and transition to lead-free.* Leaded solder is exempt of regulations for repair, prototyping, teaching etc. exactly for these reasons* Lead only presents an environmental hazard when used in large scale manufacturing of electronics some part of which will be inevitable disposed of improperly.* To sum it up, leaded solder gives more process margin in basically all relevant parameters, which is exactly why it was used for so long - and still is in demanding specialty fields. This also makes it easier for beginners.All this being said, lead-free is workable, too.

author: tooki
author_rank: Super Contributor
timestamp: June 27, 2023, 07:09:46 am
content: Quote from: Siwastaja on June 25, 2023, 07:01:41 pmI agree with all of this, with a few small comments:-only 63/37 leaded and 62/36/2 are eutectic. 60/40 is not eutectic (close, but not quite!), and is susceptible to disturbed joints.-several lead-free alloys are true eutectic, some are near-eutectic-The nickel-germanium-doped lead-free (SN100+, K100D, etc) produce joints of comparable shininess to leaded. Despite not being the lowest-temperature lead-free alloy, it’s my favorite of them.

author: tooki
author_rank: Super Contributor
timestamp: June 27, 2023, 07:10:57 am
content: Quote from: liaifat85 on June 25, 2023, 06:25:04 pmIf you’d read the whole thread you’d know it’s not as black-and-white as that. It’s certainly not an “of course” situation.

author: Brumby
author_rank: Unknown
timestamp: June 27, 2023, 10:06:56 am
content: It seems rather curious that lead/lead free is the focus of many opinions when the contact with the metal is fairly straightforward to deal with using simple procedures - but not a lot has been said in regard to the issue of fumes.I suggest they are a greater risk as they are released freely into the air and without additional equipment and proper use thereof, represent a more present risk. In that respect it would seem lead free is more of a concern.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2023, 10:53:31 am
content: Quote from: Brumby on June 27, 2023, 10:06:56 amAlso touching metallic lead is a complete non-concern, even if you licked your fingers after the fact. It simply is not dangerous, there is no such mechanism. Smoke coming from the burning flux instead is a real safety hazard, always has been, always will be. This is something to be thought of and mitigated.It's interesting how otherwise sane and analytical people are ready to make 100% feeling-based decisions when it comes to a field they do not understand (like chemistry), and not only decide for themselves, but to actually giving health advice to others pretending as if they had a clue. Even if you explain to them how wrong they are, they will just go on with "yeah,but still..."

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 27, 2023, 03:31:58 pm
content: I agree. The danger from leaded solder is nil on this situation. What is strange to me is the number of people who are willing to ignore the social situation, and go to war over being technically correct.

author: themadhippy
author_rank: Super Contributor
timestamp: June 27, 2023, 04:42:08 pm
content: Just give em a pint of milk after the lead soldering lesson.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 27, 2023, 06:44:44 pm
content: I see my point went unnoticed... I don't think anyone is claiming that there is danger from the lead in leaded solder and that is is dangerous to the operator - it is something many here have assumed people who use lead-free are thinking. Most of these posts are preemptively trying to counter the idea that simply touching leaded solder is dangerous - but no-one here is making that claim. It's almost as if people have made up their mind just from the thread title, not read any of the posts, and simply posted their entrenched opinion.Also, the difference in the harms of lead-free flux fumes compared to leaded flux is pretty small - we should all be using fume extractors and ventilation anyway.It is simply that, over the years the benefits of leaded over lead free have narrowed, where-as the enviromental harms of disposal as well as regulations and legislation have remained constant tipping the cost/benefit over to lead free. I don't know why people take these facts so personally.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2023, 07:00:01 pm
content: Quote from: Buriedcode on June 27, 2023, 06:44:44 pmThis misbelief was right in the opening post, in fact it was the whole premise of this whole thread existing, so no wonder it was discussed and debunked! Also ataradov repeated this wrong information and received many thank you's as a response,including yourself, so I don't really understand your comment. It seems you are trying to step out by rewriting history, but that does not work. Don't worry, we all make mistakes all the time.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 27, 2023, 10:51:13 pm
content: I can't find where Ataradov claimed that the danger of leaded solder is the lead.. just about fumes.You're correct in that the OP was asking about potential heath dangers of leaded solder - due to lead, but it seems many posters took a stance as if this was a common belief amongst engineers - it isn't. Imagine a non-engineer/joe public reading this thread. Half the posts are "there's no danger of lead in solder!!" which might lead the reader to assume that it is some kind of contentious or controversial issue.I have no issue with what solder people use, just the idea that somehow lead-free can be asor moreharmful for the enviroment or humans as 63/37. And I'm not sure what LF alloy people are using these days but most of it works just fine - is it that people have bought very poor quality solder and are stuck thinking that lead-free = teh bads?As for teaching potentially future engineers parts of the trade - why teach them something that is only used in very specific circumstances?

author: Jwillis
author_rank: Super Contributor
timestamp: June 28, 2023, 11:05:20 am
content: The fumes coming off of melting solder is mostly due to the flux. Very little metal is any is gassed off while melting. If your burning the metal to the point of oxidation and gassing of the metals then your temperature is just to hot.Most flux cores are a rosin base, and mostly harmless. But some stand alone fluxes can give off some pretty acrid fumes. In either case there should always have good ventilation.You should try various solders to get them used to the idea that different solders that have different melting points are for different applications.

author: Stray Electron
author_rank: Super Contributor
timestamp: June 28, 2023, 01:03:31 pm
content: Quote from: EPAIII on June 21, 2023, 05:04:24 amSame here. I spent all of two summers soldering cable terminations on TelCo frames with 63/37 solder and a 150 or 250 Watt American Beauty soldering iron with no temperature control and no fume extractor and while I was standing on a ladder! I would use almost 2 pounds of solder in a week with my face right over the solder joints but I haven't gotten lead poisoning yet. I've been soldering for at least 65 years for both work and hobby but I probably did more soldering those two summers than have for the rest of the time combined.My advice to the OP would be to use a good quality Sn/Pb/ 2%Ag solder for teaching his kids. For one thing it has a low melting point so it minimizes the risk of solder burns. The other think is that it soldersbeautifullywhich will help encourage his kids. OTOH it's expensive and somewhat hard to find and yes, it has lead in it. I learned to solder with old crude 60/40 solder and I had to use a lot of heat to get it to melt and it often didn't want to fuse to the other metals and I would push around blobs of it trying to get it to stick and occasionally one of the blobs would fall off of the table and land inside my shoe. YOUCH!When they're soldering make your kids wear closed top shoes and clothing that doesn't have synthetic material in it. If you drop solder unto synthetic materials it will melt and fuse to the skin. Ask me how I know. Wear cotton such as blue genes and a white cotton T-shirt. And NO open top shoes. We also went to the fabric store and bought large sections of plain undyed canvas ducking and used that as drop clothes to cover everything around where we were soldering. It's cheap but works well and even large blobs of molten solder won't penetrate it.And for practice soldering grab a can of the flux that they use for soldering copper pipes and and don't be afraid to use it liberally. It really, really helps clean the joint and helps make the solder stick better. I wouldn't use on electrical equipment but for training use on disposable equipment it's fine. I have actually used that and the Sn/Pb/Ag solder to solder the twists of galvanized steel cable (aka wire rope) together so that I could grind the end of the wire rope to a taper so that I could feed it into my grip-hoist. The company sells tapered cables but they're $$$$$

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 28, 2023, 01:12:55 pm
content: The advice about proper clothing and gear is spot on. Safety glasses is another option to consider.

author: Haenk
author_rank: Super Contributor
timestamp: June 28, 2023, 01:45:49 pm
content: I'd +1 to go lead free. Just to avoid discussions with the parents, who are likely scientifically uneducated and only assume "lead = death".Otherwise the only danger is swallowing the lead, or being hurt by the soldering iron or molten lead. So, long clothing (old, so it might get damaged) and eye protection is a must.For only a couple of solder spots, one might leave out the fume extractor and just open the windows. And instruct the kids to absolutely not inhale the fume. And not touch the iron or newly done solder spots.In my kids' school, they have a modernized room for physics and chemistry teaching. The workbenches have adjustable small fume extractors, which would be ideal for soldering instructions.(I think it's still funny how we all did not die back then. My father got me all the nice banned chemicals from the school lab. Lucky me. I did however move some to the toxic waste collection, some stuff was just too scary. Or experimenting with mercury, chromates, large quantities of ether in school. Now you can't even buy some real crystal growing kits for the kids as CuSO4 is obviously too dangerous. Good luck swallowing that)

author: Nominal Animal
author_rank: Super Contributor
timestamp: June 28, 2023, 02:50:50 pm
content: My first soldering iron was a 25W Antex (XS25, I believe). Worked absolutely fine for through-hole stuff, even with early lead-free solders, although I mostly used the 1mm diameter leaded solder sold in tubes –– who knows what brand, but it did have plenty of rosin-based flux inside it.After I got my first SBC and ripped off one pad (connected to its display resistive touch, so I lost touch on the display), I decided to get a new, temperature controlled soldering iron, a ZD-931, which I got from a nearby store for quite cheap (~35€ or so, a third of what a Hakko would have cost).I built a couple of kits (mostly LED blinkers) with through-hole components and the IC in a socket, using early lead-free solder, and it worked just fine.Moving to small and high-pitch surface mount devices, the problem I have with lead-free solder is that to properly melt the solder, I have to keep the iron so hot, that trying to get the placement etc. right, I dwell too long and apparently damage some of the more sensitive SMD ICs. With leaded solder, I can use a larger (thermal mass) tip and the drag method, with a much lower temperature (down in the 260°C-280°C range) and still have a few seconds to fine-tune the positioning of the chip, without exceeding the wave soldering timing typically listed in the datasheets. It helps when using ICs that cost several euros apiece.Trying to improve my SMD soldering ability, I've done a couple of the cheap cheerful Chinese kits with SMD leds and ICs, and it seems that with eutectic lead solder (63 Sn 37 Pb, 183°C) in 0.5-0.8mm diameter (to curb excessive use) and lots of flux, my results are better.For through-hole stuff, and non-sensitive components like resistors, I don't see any difference at all. It's only with sensitive SMD ICs like microcontrollers and such with very limited temperature profiles in their datasheets.Perhaps it is my soldering iron at fault? I have not measured its temperature accuracy, and it is the old cylindrical heater with the tip forming the outer shell type, not a T12 or similar with a built-in thermocouple. Or maybe I'm just a particularly sausage-fingery old bumblefuck, who should switch to using a hot plate and SMD hot air instead of forking around with a soldering iron._ _ _ _For someone with the proper equipment, it would be really interesting, useful, and educational to see how the iron tip, temperature, and solder affects the temperature measured during soldering at the IC itself, and what kind of technique gives the maximum chance ofnotburning SMD ICs (while still not lifting tracks and such on cheap boards).Me, I already use acetone and IPA with a toothbrush for post-soldering cleanup, a cheap soldering microscope for examination (and I admit, checking the tiny text on top of the smallest SMD ICs), and am looking for a nice (but cheap) T12-based soldering station, preferably one I can power from a Mean Well medical (class II isolated) supply so I can properly ground the tip with my metal work surface. I'm still experimenting with different solders, too, using a separate tip for lead-free and leaded solders.

author: tooki
author_rank: Super Contributor
timestamp: July 03, 2023, 03:49:12 pm
content: Quote from: xrunner on June 23, 2023, 10:57:55 pmSAC305 is one of theoldestof the lead-free-era alloys, one of the ones that disappoints people who are used to leaded. Try the nickel-germanium-doped alloys (SN100+, K100D, etc.). They’re the ones that behave, flow, and look like leaded, despite having a higher melting point than SAC305.

author: xrunner
author_rank: Super Contributor
timestamp: July 03, 2023, 05:06:15 pm
content: Quote from: tooki on July 03, 2023, 03:49:12 pmOh OK tooki. I was just going by what Buriedcode was using and what he said about it. But I know you are knowledgeable in these things so I'll try your recommendation.Quote from: Buriedcode on June 22, 2023, 07:14:36 pm

author: ataradov
author_rank: Super Contributor
timestamp: July 03, 2023, 05:16:41 pm
content: All lead-free solders are about the same. There is a much smaller gap between them than between leaded and lead-free. Ni-Ge are a bit shinier, but there is still a very visible difference in behavior. They are not better or worse, just different.And I actually find dull look of the lead-free solder beneficial when reworking. It is so much easier to see what joints have melted, since transition is way more obvious than with leaded solder.Using shiny surface as a quality control tool is not a real thing with modern fluxes. It was way more important when using rosin flux, but today it does not matter that much.

author: tooki
author_rank: Super Contributor
timestamp: July 04, 2023, 09:04:16 am
content: Quote from: ataradov on July 03, 2023, 05:16:41 pmNiGe alloys arenoticeablybetter. The different alloys most certainly are not all “about the same”.

author: janoc
author_rank: Super Contributor
timestamp: July 04, 2023, 02:27:32 pm
content: Quote from: ataradov on July 03, 2023, 05:16:41 pmIt is sort of important when teaching kids to solder, though. They need to be able to recognize a bad joint - whether or not it happened because of not enough flux, not enough heat, dirty components, board or the iron tip doesn't matter.Obviously, one can't rely only on whether the solder is or isn't shiny - but it was a useful first indicator that something isn't right.

author: Nusa
author_rank: Super Contributor
timestamp: July 04, 2023, 03:21:17 pm
content: Quote from: jimjam on June 21, 2023, 01:37:17 amThe opinions about leaded vs non-leaded quality are irrelevant in this case. You can make the decision for your own kids, but with other peoples kids the decision is overwhelmingly obvious from today's social and legal standpoints. For the age groups mentioned, I'd suggest that every child have a parent be included in the learning sessions, if only to make sure there are enough eyes on the children. At some point someone is going to burn themselves by accident. That's practically a guarantee! For the same reasons, make sure you follow safety procedures you might not use yourself....eye protection in particular.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 04, 2023, 04:02:13 pm
content: Quote from: Stray Electron on June 28, 2023, 01:03:31 pmBack in the days when I was a youngster learning to solder, I used the infamous 60/40 solder and a Weller solder gun. I was struggling with a wire joint and a large blob of molten solder landed on my pants. These being the 70s, I was wearing long hair and my bell-bottom pants, which were made of a synthetic fiber called Terlenka, if I recall correctly.The solder blob completely melted the Terlenka fabric, which adhered to my skin. I had to go to the hospital to have it scraped off.It left a scar which I still have, 50 years later.

author: Smokey
author_rank: Super Contributor
timestamp: July 05, 2023, 04:01:18 am
content: Quote from: ataradov on June 22, 2023, 10:49:37 pmTell that to my hot air rework station which needs to be set significantly hotter and run longer to rework lead free parts.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 05, 2023, 05:36:50 am
content: Quote from: Nusa on July 04, 2023, 03:21:17 pmYet to me it is overwhelmingly non-obvious what is so obvious to you. Leaded or lead-free? (I'd assume you mean leaded since is it poses smaller health hazard, but would you agree or not?) Or not soldering at all? Would you mind sharing what is so obvious?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 05, 2023, 07:29:41 am
content: In terms of them learning to solder well, a much more important consideration is to use a decent temperature-controlled iron with a chisel tip, not the conical garbage usually supplied as standard

author: Siwastaja
author_rank: Super Contributor
timestamp: July 05, 2023, 08:26:42 am
content: Yeah, and to clarify that, "temperature controlled" doesn't necessarily imply "it has an adjustment knob", but that it has a thermostat sensing tip temperature. Old-school Weller irons (where the tip itself loses and regains magnetization according to temperature and controls a magnetic switch) are really popular here in schools etc. and they are just excellent irons, for beginners, schools, professionals, or production (except when the switch wears out and the thing becomes stuck on/off, usually off, but it takes gazillion of operating hours to reach that). My observation is these old simple things react to temperature changes keeping correct tip temperature way better than many newer digital adjustable irons. One only needs to order correct tips, which are not expensive, but the process of knowing what to order, actually ordering them, and not losing them somewhere in the lab seems to be the hardest part. The best overall tips for mixed SMD/TH work would be like 2mm and 5mm chisels; in case of old-school Weller, temperature 7 for leaded and 8 for lead-free.The best feature of the chisel tip is, when you sometimes need to solder some tiny thermal mass pin (say, a bodge wire to 0.5mm QFP package pin), you can just tilt the iron and use the sharp corner of the chisel; chisel itself can be bigger, 2.4mm is OK to surprisingly small things. Then when you need to solder something larger, just use the whole length of the chisel for more contact area, or the whole facet for even more. No need to swap tips that often!

author: jimjam
author_rank: Regular Contributor
timestamp: October 05, 2023, 06:20:16 am
content: Here's the result. A 6yo, first time doing it after doing some practice with a Vero board. Lead free solder. It's quite easy to work with.

author: ataradov
author_rank: Super Contributor
timestamp: October 05, 2023, 06:52:48 am
content: This looks good.A more important thing - did they enjoy it?

author: jimjam
author_rank: Regular Contributor
timestamp: October 05, 2023, 12:26:23 pm
content: Quote from: ataradov on October 05, 2023, 06:52:48 amIt seems so. He wants to do more. I need to find where to get some fun "electronics kit" to make / solder. The "Piano" kit that he did came from aliexpress, but it is terrible. It doesn't play the correct notes, I'd need to replace the resistors.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: October 06, 2023, 03:08:29 pm
content: Quote from: EPAIII on June 23, 2023, 06:30:31 amSpoken like a true Texan. 100 likes. I feel the same way about mercury. Haven’t died from either one yet.