You have strong opinions on the use of leaded solder. I'm curious if you have some numbers to drive home your point. For example, what is the relative risk of using leaded solder for a hobbyist creating a handful of prototype circuit boards a year (using proper ventilation of course), versus living close to an airport exposed to burning jet fuel which contains lead to this day? I want to know, roughly speaking, if using leaded solder a few times a year cause 100X more exposure or only 1/100 the exposure compared to living near an airport. If it's only 1/100 compare to an airport, I'm not going to worry about it. If it's 100X, then I think your position is quite valid. [Addendum: Another example, what is the risk of leaded solder compared to lead exposure from common household items like brass knobs, handles, fixtures, and keys?]

My current inventory of solder was obtained from estate sales, so they are all leaded, but old stock, not newly manufactured. If I had not bought them, they would have been thrown away into the garbage dumps.

Jet fuel does not contain lead. Jet fuel is for practical purposes roughly the same part of the dinosaur juice as kerosene and diesel. Jet fuel is burned in turbine and turboprop airplane engines, which comprise the enormous majority of the commercial fleet.

Avgas is the stuff with lead in it. Avgas is basically gasoline with lead added as an anti-knock agent and is burned in reciprocating spark ignition engines. Typically these are found in the general aviation fleet.

A simple observation that cannot be refuted because it's an already accomplished fact that I have no problem soldering with 305 (or anything else really) is not a strong opinion.

All anyone can say is that maybe I'm lying or maybe don't know what a good job looks like and so don't know I'm actually having problems. Or maybe I only ever tried within a narrow sliver of ideal situations and conditions. We will all just have to grant each other some basics like that or else there's no point in conversing at all.

But it's farcical me to say "I use it all the time and it's fine." and respond "You're wrong."

Really? I didn't just do the thing I just watched my hands do right in front of my face? This project in my hands is not actually soldered? And doesn't actually work? Am I in an Elon Musk simulation or something?

My physics are not different from your physics. My sac305 is not different from your sac305. My 300-350 degrees c is not different from your 300-350 degrees c.

Such basic implacables are not a "strong opinion"

But, it's true that, having examined the basic facts and tried things myself, I have now arrived at a conclusion that is a rather strong opinion that the crybabying is nothing more than that. 63/37 is a little easier and that's all there is to that.

Are you sure you are replying to correct post? Some people in this thread are resorting to name calling. That is unfortunate, but that's not me.

All I wanted was a sense of the relative risk of leaded solder compared to the other sources of lead around me. That's all. I figured that someone with such strong opinions as yours would have that sort of information.

I have no opinions regarding the ease of use of leaded solder versus unleaded solder. I actually don't know what sac305 is... Google tells me it's 96.5% tin, 3% silver, and 0.5% copper.

Ok sorry.

Yes sac305 is a common lead-free solder. It's not easy to replicate the properties of lead-tin alloy, so there are a lot of different alternatives and none of them really work quite as well.

There's 2 classes of problem: usability and functionality. Lead-free is both a little more difficult to use, and then is a little more likely to fail over time.

Usability: The usability problems are 2 things, higher temperature, and surface finish.

In the best case with old lead-tin, you still have to develop a skill to get in and get out relatively quickly and not keep the heat on for a long time. Even the relatively lower old temperatures are still hot enough to destroy most components and the pcb traces if you lay the heat on for extended times.

But all of the lead-free alternatives require a little bit higher temperature, and so there is a smaller window of time to goof off and blunder around with the heat on. Smaller but still easy enough. A datasheet for a component might say something like max 300c for 3 seconds, but really you can poke around for 30 seconds at 350. 30 seconds is forever. If you can't get it done by then, the problem isn't the solder.

The surface finish matters because in the old days it just so happened that you could be a cave man and still know if you made a good joint or not simply by the surface finish. If it's shiny, it's good (probably), if it's dull, it's bad. sac305 usually cools to a dull finish even if everything is perfect. You can still tell if you made a good or bad joint, it's just not as utterly black/white simple as before.

Both of those are just, it's a little more difficult. Still perfectly doable and not just by some wizards and not by most mortal humans.

Funcionality: The most valid problem is the performance, where after doing the sufccessful soldering, the solder fails in some way later on.

sac305 and most others are generally a little less ductile and prone to crystalization and fatigue cracking, and the biggest problem is tin whiskers.

sac305 is pretty much the worst for growing tin whiskers. On fine-pitch legs on surface mount parts the pins are close enough together that in bad enough environmental conditions, whiskers can grow to short between two pins eventually.

But, it takes particular conditions and doesn't usually happen to most ordinary things kept in ordinary indoor environments, and if you're building something that has fine pitch parts and you know it will be used on a boat or something you can mitigate that by adding a coating, and lastly in this case, point-to-point wiring in an antique radio is way too large to have any tin whisker problem. Whiskers grow to something like 500um in the worst case. It takes both a bad environment (presumably and "antique radio" will be protected and not used on the deck of a saltwater fishing boat) and requires parts that are almost touching each other. Antique radios don't even have PCB's. Medium-old electronics that havs pcbs but through-hole parts are maybe barely subject to whiskers. It will be uncommon for a whisker to reach all the way between 0.1" (2.54mm) chip legs, but not impossible.

These things are certainly problems. That's true. Yet it's also true that most electronics have been using nothing but this stuff for almost 20 years already by now.

There has been exceptions allowed for specialized things where the functionality and performance of the lead alloys was necessary enough to outweigh the environmental impact. But they are about to remove a lot of those exceptions soon. It is a problem, but it's not a problem for any hobbyist.

This subthread, my reaction, was exactly about the suggestion about "some retro guy repairing an antique radio". That guy absolutely not even close has any need for lead solder, and yes, that one guy using it does poison the environment, because there is no such thing as one guy. It's countless guys. If one guy can buy and then use something, then so can everyone else. And for every one of those users, theyr aren't just soldering a few joints one time. They have 1lb spools of solder and ALL of that solder eventually winds up in the ground and leeching into the water and soil. Most of it actually gets turned into fine dust because that's what happens when you clean the tip, which you have to do continuously, and when you desolder something, the vacuum atomizes the liquid solder as it's being sucked out of the via.

That's why it's so bad. There's no such thing as just one guy doing it, and for every one of the people, imagine taking a pound or two of lead (solder isn't 100% lead, but a single person will posess a few pounds or more total of different solders) and imagine say 10% of that lead being actually in some project. Then another say 30% being in the form of little bits and pebbles and the size of a bb and discarded joints like bits of soldered wiring cut off and discarded, and the rest, say 60% all in the form of particles the size of sand all the way doewn to very fine dust. And all of that solid pound of finely ground pebbles, sand, dust, ends up just everywhere, only some ends up in the local dump. a lot ends up just in the structure of the house and the ground under and around it right near wherever the work bench is. When you sweep and vacuum your work area, you are not remotely actually recovering all that lead dust.

And the next family to occupy that land didn't sign up for that.

When I say "no excuse" I mean that, there is no overriding need that justifies it. Sure lead-tin works better both while using it and then klater for the life of the object, but it doesn't work better enough, and for most people the application isn't critical enough, for that to outweigh working towards the goal getting led out of the environment.

Unleaded gasoline is way more difficult to use and less performant and has cost everyone billions, and we all shouldered that burden, only so that some man-baby can undo that very difficult and costly work just so they can solder a wire in a radio a teeny little bit easier?

No. The two considerations don't compare at all. It's just that one is easy to see and one is not so easy to see. One you can see with your eyes right now and gives you immediate gratification, and one you have to see with your mind, and you have to care about anything but your own convenience as the single most important consideration above all others.

Sorry, but as someone who has had to use them, lead-free solders are garbage. They are difficult to work with, require higher temperatures to use, don't last as long, whisker and destroy equipment they're used in.

This is all well known, it's not a mystery, and lead in solder is the least of the problems with lead in the world today.

If all you've used is crappy old SAC305 lead-free solder, you owe it to yourself to try a modern alloy like SN100C (& friends, it has several names and similar competitors). It's generations newer and with the right flux (I like AIM's Glow Core wire) it's just great for routine work. It runs a little hotter, but most people already solder too hot anyway, so who cares.

I still use 63/37 or 62/36/2 for anything challenging, though. Or for old rework: many people in this thread are missing that you really, really shouldn't mix alloys on a joint, so you've got to get the old stuff out before switching to lead-free, and at single-joint scale that's a lot more polluting than just grabbing the spool of 63/37.

I'll definitely agree that you shouldn't rework old joints with different solder.

How come I have no problem? Even with plain old sac305 let alone the supposedly nicer ones.

From big old chunky point to point, to manually drag soldering 0.5mm pitch tssop.

I have no problem doing something that you claim is impossible or too difficult, and somehow this makes me the crybaby?

Ok.

Frankly if it was me I wouldn't be so keen to tell everyone how weak and incapable I was.

I grew up on leaded as we all did. I used to really like the radio shack 0.015in 62/36/2 silver bearing. Did indeed work very nice.

And yet after an inconsequentially short maybe a single hour of effort, I was able to adjust to 305.

You telling me I'm just better than you? Well if I'm just better, then shouldn't you be listening instead of arguing? If I'm not better, then how do you explain my lack of difficulty with something you claim is difficult?

You're putting a whole lot of words in my mouth and setting up a whole field of straw men there. Good luck with that.

You are aware that leaded solder is in use in many industries to this day?

I'm soldering with SN62 now as we speak.

You are aware that this means, validates, invalidates, nothing?