Ask Hackaday: Get The Lead Out Or Not?

For most of the history of industrial electronics, solder has been pretty boring. Mix some lead with a little tin, figure out how to wrap it around a thread of rosin, and that’s pretty much it. Sure, flux formulations changed a bit, the ratio of lead to tin was tweaked for certain applications, and sometimes manufacturers would add something exotic like a little silver. But solder was pretty mundane stuff.

Source: RoHS Guide

Then in 2003, the dull gray world of solder got turned on its head when the European Union adopted a directive called Restriction of Hazardous Substances, or RoHS. We’ve all seen the little RoHS logos on electronics gear, and while the directive covers ten substances including mercury, cadmium, and hexavalent chromium, it has been most commonly associated with lead solder. RoHS, intended in part to reduce the toxicity of an electronic waste stream that amounts to something like 50 million tons a year worldwide, marked the end of the 60:40 alloy’s reign as the king of electrical connections, at least for any products intended for the European market, when it went into effect in 2006.

Unintended Consequences

Whether the intention of EU regulators when adopting RoHS was to completely shake up the electronics industry is a moot point, because that’s pretty much what happened. The industry initially dug in its heels and made arguments against switching to lead-free solders, some of which were valid enough chemically and electronically to earn exemptions from RoHS. But lead-free solders, mostly tin with copper and silver mixed in, became the law of the land for most consumer electronic products.

NASA hates tin whiskers, but they’re probably not a reason for you to avoid lead-free solders. SOurce: NASA Electronic Parts and Packaging Program

Despite the industry’s early predictions of doom from lead-free solders, manufacturers adapted to the changes well. Processes for wave soldering and reflow were changed, new flux chemistries were explored, and in general the predictions of a world gone haywire from the short-inducing whiskers that were sure to grow like weeds from tin-based solders failed to happen. Exemptions were granted for applications likely to suffer from whiskering issues, but for consumer products, lead-free solders became mainstream pretty seamlessly.

But that doesn’t mean that everyone is sold on a lead-free future. That’s what Zach Fredin, Superconference regular, badge hacker, and open-source hardware entrepreneur, discovered when he recently tweeted his feelings about going 100% lead-free in his soldering. Zach got a fair amount of push back from his followers, some of whom tweeted back that they avoid lead-free solders because the flux fumes from them are more toxic.

The battle was then joined by Ben Hencke, another lead-free fan. He noticed Zach’s tweet and the oppositions to it, and instead of going with his gut, he went to the literature. He wrote up his findings in an interesting blog post, wherein he details what he found when looking over the Safety Data Sheets (SDSs) for two Kester solders, one leaded and one lead-free. Basically, his read is that both solders contain the same flux, from which he concludes that flux toxicity is a specious argument for sticking with leaded solder.

It’s All About the Flux

But is that true? While these two particular solders have the same flux cores, I don’t think you can make the argument that the flux fumes are the same, which is of course what counts. Lead-free fluxes typically require more heat than their non-RoHS cousins, and greater heat can vaporize more of the flux, resulting in more fumes. What’s more, hotter temperatures could potentially alter the chemistry of the vaporized flux, making it more toxic. Something like that happens with grilled meats, where cooking over an open flame leads to the creation of heterocyclic amines and polycyclic aromatic hydrocarbons in the smoke, potential carcinogens which waft up onto the meat in the smoke.

Smoke gets in your eyes – if you’re not careful.

Could this be behind the claims of lead-free fluxes being worse for you than the fumes from traditional fluxes? I don’t know, but I do know that it gives me pause, and makes me rethink the whole lead versus lead-free debate. I think both Zach and Ben have valid points, and I applaud Ben for taking the time to actually read the SDSs and reporting on what he found. It’s persuasive, but I’m not willing to switch to 100% lead-free based solely on the that.

Here’s where we turn it over to you, dear readers, for we’re fairly certain you have strong and varied opinions on this issue. What do you think about the whole lead versus lead-free debate? Do you feel like there’s more risk from the metals in the solder or from the associated flux fumes? Have you seen any studies that analyze the composition of fumes from different solders? Or is this all a red herring as long as proper fume extraction and common sense safety measures are employed? Sound off in the comments below.

157 thoughts on “Ask Hackaday: Get The Lead Out Or Not?

      1. I’ve always thought they could have tiny leaf spring bumps on the PCB, spot welded or soldered or whatever, and you’d just clamp parts on with a plastic tray.

        That way even replacing a BGA would be trivially easy as long as you didn’t spill the other parts.

  1. I still use lead because I have a toaster oven converted into a reflow oven, and it isn’t powerful enough to properly do a RoHS profile without taking too long. Lower temperatures also mean bigger margins for error and less trouble from moisture sensitive parts.

    I do occasionally have batches of things manufactured for me, and those folks use RoHS. And that’s fine. But I’m grateful that SnPb hasn’t been made unavailable for hobbyists here. Yet.

    1. Even some of the larger cheap chinese reflow ovens I’ve found don’t heat evenly enough for a RoHS profile. A small board maybe, but I recall doing a few panels and accidentally used lead free, and wondered why I had to turn the profile up to something board-scorching to get it to reflow. And that’s part of why I still use lead paste.

      That tube has since been CLEARLY marked :)

    2. I still hand solder with lead as its easier. As an occasional operator I find it flows and wets much better, and of course with a colder iron I melt less of the part I’m trying to solder.

    1. Citation please?
      My quick search shows that silver is easily corroded (tarnish is Ag2O or Ag2S), and that silver nitrate (AgNO3) is corrosive, but you seem to be saying that silver itself is corrosive. Are you talking about galvanic corrosion? If so, how is it worse than lead-based solders?
      Or if its purely anecdotal, perhaps you’re mistaking the source of corrosion as the solder itself, rather than the rosin you left behind.
      The heat, on the other hand, I agree with. There’s times I use Bismuth solder paste just to avoid the high temps when I’m reworking a board.

      1. It’s not “corrosive” as such, but rather a solvent – the silver based solders tend to alloy easily with copper, and dissolve the traces on the PCB that way – by drawing them into solution with itself. It appears like the solder is corroding the metal.

          1. Only when liquid, but not necessarily marginal, For Pb based solders, the solubility of copper is pretty low at the temperatures involved. For Ag solders, the copper will be more soluble at a given temperature, and the temp is higher than with Pb solders.

            The ideal in soldering and brazing is minimal dilution, with the intermetallic layer being thin. As more copper dissolved into the solder, the intermetallic layer get thicker. This leads to a number of issues, such as the intermetallic is often brittle (mechanical issue), may not be as conductive as the filler and will not be as conductive as the copper (electrical issue– resistance and heating in service, for example), and as well as depletion of the copper thickness at the joint location, adding to both the mechanical and electrical concerns, in particular if the copper is very thin to begin with.

            For more information, there are a lot of resources. Google intermetallics in soldering.

      2. It could be galvanic action. Copper (track) is more electronegative (ie more reactive) than Silver, and less so than Tin and Lead. This means that Copper track would leach away in the presence of an electrolyte (flux) and a Silver joint, whereas the Tin/Lead joint would leach away in the presence of flux and a Copper track. As the joint tends to be thicker than the track, the track leaching away could be more of a problem than the joint?

    2. Silver isn’t corrosive, although it IS antimicrobial. It is sometimes used as a coating for medical implants, and occasionally even for wiring bones and the like.

        1. When my daughter was young she received a terrible burn the length of her forearm. The cream the medical people gave us for it was based on silver colloid, and today you can’t even tell she was burned. I had the same experience with a wound that wouldn’t heal.

          Only two data points but far as I’m concerned those silver-based antibacterial creams are great.

    3. Silver isn’t corrosive. The material being soldered may dissolve more readily into a higher silver content filler during the soldering process for a number of reasons, the higher temp than Pb based solders being one (think sugar dissolving in water… This alloying at the interface is a critical part of soldering and brazing for strength and for electrical properties).

      There may be enhanced electrolytic corrosion in some cases, relative to Pb based filler, depending on the exact alloy, service conditions, and production technique (heat cycle, flux, etc)

      1. In general, most people will find SAC305 will solve most use cases.
        1. It will stick to almost anything given the silver content
        2. the silver content is high enough that damage to coatings is negligible (oddly lower is worse)
        3. the NASA and Japan Whisker studies suggested this alloy rarely develops growth sites due to the impurities it strips off
        4. Pulp plant Whisker studies show near some chemistries like Hydrogen sulfide even aluminum alloys in heat-sinks can develop issues

        Personally, I prefer the classic 60/40 leaded option for equipment, as the lower temperatures are less likely to cause problems during repairs. The other reason is that it costs about 3 to 4 times less than the silver solders.

        We made a choice to go with SAC305 for the health of people exposed to the metals everyday, and you do need to use Ti based equipment to handle it while molten. If you don’t the molten alloy does slowly degrade surfaces it comes into contact with over several weeks, and as bizarre as it sounds a lower silver content alloy actually makes the process more aggressive.

        Note, SAC305 does tend to alloy with the wire coatings somewhat, but this is usually desirable given pure tin plating is so much more of a problem. Some factories specialize in stripping off Tin and re-plating for aerospace companies.

        I wish silver solders were cheaper, and less prone to oxidation without nitrogen gas shields… as most consumers are price sensitive… and I hate to admit without RoHS we would all still be using Lead.

        We create our own fluxes in house from regular rosins, and it works fine. There should be nothing special going on in this part of the process. ;-)

  2. I HAVE to use Pb-free at work, but at home, I use 63-37.
    I tried to use one of those Pb-free solders that wasn’t straight tin.
    If it was supposed to be “better”, (wetting, flow, adhesion) I didn’t notice.

      1. Can confirm.
        We order our boards Pb free (because we have to) but if you want to rework them, it’s PbSn all the way (sometimes with a little Ag thrown in for conductivity). I have a huge stash of Pb/Sn/Ag from my father-in-law, who worked for F W Sickles Corp, back in the olden days. THAT stuff is great to solder with (but a little thick for today’s PCB technology)

        On the other topic: he may think Ag is corrosive, because “silver solder” used for jewelry (NOT for electronics, except in rare circumstances where mechanical strength is needed – antennas for example) sometimes uses a corrosive flux.

  3. Good lead free solder works almost as well as solder with lead, but the cheap stuff can be very frustrating to use. The range of variation seems to be even wider for copper plumbing than for electronics.
    I have a lifetime supply of 63/37 leaded solder at home and don’t plan to switch. At work, I use lead free solder and rarely wish I had leaded.

    1. I use tin-lead exclusively, at least so far. I know that lead-free formulations have improved, so my historical experience may no longer apply. But I’ve done a fair bit of repair and rework on RoHS PCB’s that have terminal blocks for high-current connections. Over time, thermal cycling, and vibration, I have seen many of these solder joints fail in ways that I have never experienced with lead-based solder. They become more crystalline and brittle than even the coldest and crappiest of solder joints using lead. Other joints on the same terminal blocks, (ones that don’t carry heavy currents), are invariably still OK. So even if I move to lead-free solder, I will probably maintain a separate iron for using lead-based solder on any high-current connections.

      One advantage I found for lead-free solder while I was looking stuff up while reading this article – it plays much better with gold plating. So if you’re soldering any gold-plated connectors or leads, lead-free is the way to go. More valuable info available on Wikipedia – https://en.wikipedia.org/wiki/Solder .

    2. “I have a lifetime supply of 63/37 leaded solder at home and don’t plan to switch. At work, I use lead free solder and rarely wish I had leaded.”
      This. I did the same thinking it was going to go away when they announced ROHS. I’m never using that solder.

  4. I have used both leaded and lead-free. I don’t like the work-ability of the lead free stuff. It doesn’t seem to wet as well, it doesn’t flow as well, it requires higher heat. I buy the old fashion Leaded stuff. Now get off my lawn….

  5. Lead free isn’t for the benefit of the manufacturer, or even in many cases the direct consumer. It’s for the public at large. Many electronics are effectively disposable or at least have planned obsolescence. All this tech trash causes major pollution and clean water issues.

    Unless we overhaul our recycling and tech life spans, RoHS is worth the extra hassle. Now for your own hobby projects, I doubt you’ll produce enough waste in your life time to do much damage. Just wash your hands before feeding your kids.

    1. The irony is then that RoHS solders make these products throw-away because of the resulting bad solder joints that won’t handle as much stress, cold, chemical environments or the time.

      1. I was thinking that. I have seen new consumer and industrial products failing in strange ways after a relatively short life but the 500hp VFD from the 80’s that lives in an ventilated closet is still chugging away. I know anecdotes != evidence but you go with what you know.

      2. This! How many boards and components are thrown to the garbage in the era of “don’t replace a part , replace the board” are caused by bad solder joints from RoHS soldering… It’s safe to dispose of , yet there is so much more junk that reaches the landfill , I don’t see where it’s safer for the environment.. I’ve repaired tons of devices by re-doing the solder, with lead..

        1. That’s not the point: planned obsolescence enables the use of poor solders because the soldering quality isn’t going to pose a problem for a design that is only meant to be on the market for two years and break in three or four.^

          If the critical feature of that design was improved for a life beyond the designed consumer cycle, the product would fail anyhow because of the use of poor materials like RoHS solders, which only became acceptable because products didn’t need to last. In other words, even if you didn’t design the product to fail, it would still be a throw-away after a couple years because now you can’t design with proper materials anymore, cheaply at least.

          It could be called obsolescence by regulation.

          ^(The designers of things like laptops, or cellphones, etc. are changing the model every 1-2 years to hide the fact that they do tend to break. If you ask “Is laptop model Y any good?”, you won’t find many people who could tell you from experience, and by the time there are enough people to tell you, they don’t sell the model anymore.)

      3. the type of solder doesn’t have thing to do with disposable consumer electronics. The manfacturing techniques, that create an economy of scale tat make it unbelievably inexpensive to purchase new items. Those machine constructed item are difficult and expensive to repair quickly, to the point the average consumer, is going to purchase new A return to lead solder isn’t going to change that dynamic

        1. It isn’t even about the machine assembly.

          It’s easy to design mechanisms that go together, but don’t come apart, like a snap-fit case that cannot be pried open without breaking it. It takes more effort (money) to design it to open again.

      4. I hope you have data to back that up? Because IME the problem is designs that can’t be repaired reliably, due to increased packing density and choosing not to make things repairable.

        This is one of the standard arguments against lead free together with whiskers and I’ve never seen anyone produce anything other than hand-waving.

    2. so, you mean that if I would use lead-free I can feed my kids WITHOUT washing my hands (first)? Wow, that would save me a lot of time on a yearly basis, thanks for the tip.

    3. Is metallic lead hazardous? Like the mercury in my dental fillings? (Yes, a very little can be hydrolyzed in the blood stream). Check the results for people who work in lead mines and lead smelters.

      I use 63/37 eutectic wire and paste. Why would anyone use anything else? RoHS was feel-good knee-jerk from the beginning. Was anyone actually injured by solder in electronic garbage? Organic lead compounds can be absorbed through the skin and are bad stuff. How would you synthesize them in a dump? (To me it is like banning hydrocarbons in air because they might form cyanide).

      1. Yes. And yes.

        Like you said it’s not horribly dangerous, especially for adults, but it’s best avoided. The concern isn’t metallic lead, it’s that few things stay metallic in nature and heavy metals hang around for a while. They also bioaccumulate which causes issues for predators, like humans.

    4. One well documented problem with RoHS solders is that they can form tin whiskers. This was known phenomenon going all the way back to the early 1940s at least. These whiskers grow slowly and then eventually short things out, and vaporize, giving rise to an intermittent failure.

      So what this solder does is guarantee obsolescence. This is particular concern for space agencies such as NASA. See https://nepp.nasa.gov/WHISKER/

      Research has discovered that if we don’t include at least a 3% lead content in the solder alloy, that it will form whiskers. The RoHS committees probably knew this (or if they didn’t, there was plenty of literature out there that could have told them that).

      I understand wanting to reduce the use of lead. But how environmental is it when you have to trash an entire device because it is becoming intermittent due to the solder?

        1. Not sure, but after looking into the lead-free solder debate, I’m thinking about doing a piece on metal whiskers and how they form. Maybe I’ll find out how to fight them in the process.

          1. Step one: Move to space, or a really arid climate.

            Step two: Focus on equipment with high power, high frequency radio transmitters.

            Step three: Wait a long time, and if you’re lucky, you’ll find one.

            In a coastal climate… build a climate box. You’re going to need it.

          2. Tin whiskers also grow in response to mechanical stress, so things like unibody Macs where the circuit board carries the load imposed on the frame, there’s a tendency for tin whiskers between pads and traces.

            This is a problem for tiny SMD components and ball grids, not so much the NASA problem of whole forests of whiskers growing between connectors or wires, which doesn’t usually happen because the whiskers corrode away and turn to dust…

        2. I have personally experienced the failure of a ceiling fan light power limiter and very expensive high-reliability hardware due to tin whiskers. I am aware of nothing that stops tin whisker formation aside from the addition of 3 weight % of lead in Sn based solders. There are, however, mitigations. Mitigation is risk reduction, not risk elimination.

          Urethane conformal coatings are one way to mitigate whisker growth. Whiskers can grow through and out of urethane conformal coatings, but not back into it. Bridging of a conformal coating between leads of a DIP package is as bad as having no conformal coat at all.

          Parylene coatings are used as well, but whiskers still grow. Whiskers may not exit the parylene, but they definitely cause “bumps” and there may be a curl back of the whisker. Of course curl back is possible with any conformal coating that has a high surface tension.

          There has been mention of the NASA web site regarding tin whiskers. Indeed, look at the content of that site, it is an excellent resource.

          Regarding the lead-in-anything ban; it is a knee-jerk feel good effort, not based on credible science. Sorry lemmings, tree-huggers and snowflakes — the lead ban is based on the same sort of junk science used to promote global cooling. I mean global warming. No, wait, I mean climate change. Is lead toxic, of course, in high enough concentrations; so is water. Did it cause mental retardation and degradation in that historic case of a kid chewing on a window sill painted with lead based paint? No more than his living in a depressed inner-city environment rife with poor nutrition, violence and drug problems did. Possible external causes were not considered for Frank X’s behavioral deviance. And for that, we now suffer the loss of lead from everything, including electronics – which in electronics drives reliability down. But hey, it’s great for creating jobs in China to make more electronics that fails prematurely. Electronics that they recycle the parts from and sell back to us as new. Ah, the circle of life!

      1. “But how environmental is it when you have to trash an entire device because it is becoming intermittent due to the solder?”

        Well, that depends. It depends on the environmental impact of the board with lead-free solder, the rate of failure of lead-free boards versus leaded boards, etc.

        Let’s not forget the obvious though: ALL boards end up in a landfill at some point. Unless there is actual evidence that using lead-free boards necessitates an increased production of a product and the sum total of that increased production has a more deleterious impact than a reduced production with leaded solder, it seems clear that the lead-free solder is a more environmentally responsible choice.

  6. I went all lead free for a while, but there were certain parts that I could not place effectively and it was causing my prototypes to fail. So while my production runs are RoHS compliant, for prototyping I use a combination of lead free for simple joints and leaded for difficult joints.

  7. >”and in general the predictions of a world gone haywire from the short-inducing whiskers that were sure to grow like weeds from tin-based solders failed to happen.”

    Product lifespans these days are too short for tin whiskers or tin pest to become a problem.

    Yet these days certain electronics products have become more “fragile”. Where previously you could forget your cellphone in your car and let it freeze overnight, doing that to a modern device can kill it. When it was all made with leaded solder, you just didn’t have to think about it because lead pretty much solved the tin pest issue as well.

  8. I remember this fight well… But my issue with the lead-free was with the decreased reliability of lead-free solder joints. We were building high-reliability products and ALL the LF reports at the time stated that the reliability was significantly decreased from SnPb solder. Component leads have been lead-free for decades, and ENIG has high brittle fracture failure rates and ENIG was the surface finish of choice going lead-free. Luckily, I had final say over what we used and even though everyone wanted to go to SAC305 I held fast to Good Ol’ 63-37 and we never had an issue with it. When I was forced to switch, we went to SN100 because the reliability was higher than SAC305.

    If you read the IPC round-robin test report on lead-free solder, the only reason they recommend SAC305 is COST. Not reliability.

  9. I inherited spools upon spools of leaded solder from my father, and I cannot imagine any scenario where I run out and am in a position to purchase more solder that would be lead-free. I do use lead-free solder paste on the rare occasion where I’m reflowing.

    I don’t like lead, I don’t like handling it, but its what I’ve got and its wasteful and expensive to chuck it. I admit, I haven’t ever tried to hand solder with Lead-free.

          1. I wrote thinking about cobalt in lithium batteries, but I just realized it might be seen as a reference to cobalt-60. I don’t what a lithium bobber has to do with depleted uranium.

  10. >What’s more, hotter temperatures could potentially alter the chemistry of the vaporized flux, making it more toxic.
    A lot of people use very high temperature setting on their soldering iron, so the effect would be there even back in the days when we use lead solder. I notice that the settings are always at max (and the solder tips were in bad shape) at the labs I worked in.

    The higher melting points make it more difficult for reworks especially for parts that are soldered to power/ground planes.
    Forget it if it is a through hole part soldered to multiple ground planes on a thick multi-layer board.

  11. I try to avoid the fumes anyway, so that would not be a comparision point. But from practival evidence, when repairing the new-fangled rohs appliances, the temperatures starting having to be much higher, and problems due to overheating the pcb or nearby components have also increased.

    In some boards, I suspect the failure reasons are due to rohs smaller resistance to thermal cycles, because many of the faults seem to be cleared when removing the component, clearing and retinning the pads with good old leaded solder, then resoldering the same component ….And it is in a position that I believe to suffer more from heat during normal operation.

    Same as with the discussion and persecution of plastic bags : if you use the thing correctly, then it works without problems. If the problem is with too much electronic waste, well, then that should be addressed, instead of creating other kinds of problems.

    How about some initiative where you can take an old piece of electronics somewhere, receive real money for it, and be sure it will be either repaired and reused, or correctly recycled ?

    1. The problem with that is too many devices are worth less in their materials value than the cost of labor required to safely take them apart. Destructively rip apart a MacBook Air or iPhone 5C to get the glued in battery pried out so the rest can be shredded for metals recovery is at best break even. Take some care so that good parts can be saved for sale to 3rd party repair companies like Rossmann, you’re losing money due to how much time it takes.

      For the USA, the 1996 Battery Act needs to be amended or repealed and replaced with a law that covers ALL battery chemistries, not just Lead Acid, Nickel Cadmium, or batteries containing Mercury.

      That Act boosted the adoption of Nickle Metal Hydride and all the variations with Lithium, so companies like Apple could continue to thumb their nose at their customers with glued shut products.

      1. Never heard of the 1996 Battery Act, but if revising it would prevent companies from sealing Li batteries in cases, I’m all for it. It’s sick how many devices end up trashed rather than repaired.

        By the way, I don’t believe repealing RoHS will help even if it did make our solder joints more brittle. We have disposable devices because of economics, not solder. Companies save money by not over-engineering their devices, which nowadays means not lasting more than a few years. Profits are furthered by efficiency, but the flip side is we’ve become quite adept at cutting excess quality based on a product’s predicted lifetime. Most consumers don’t care if a device breaks because they are so cheap to replace. There is no market incentive to look at the cost to the environment.

        If disposable devices are the way we’re heading, we should go all the way. Twenty years ago, I remember reading about people working on computers that would be compostable. That’s a great idea given how fast technology becomes obsolete. But, if we ever do switch to it, I expect a hue and cry from some engineers about, “In the good old days, we used AgSn solder and the joints lasted decades! Now we have to use this meat-glue which dissolves when you look at it funny! It’s a good thing I stocked up and have a lifetime supply of inorganic solder!”

    1. It’s used heavily in production LED applications where the dies are heat sensitive. I’ve used it a lot in prototyping and teaching, it’s awesome, the process window is enormous so it’s great for rework and hand-assembled reflow.

    1. You can’t beat the smell of soldering on an antique electronic device, say from before 1970. I’m sure it’s a potent cocktail of all the hazardous materials that have been banned over the years, but man does it smell good.

      1. Ammonium chloride, which is only one step away from hydrochloric acid. I used to have an entire container full of flux from the 1950’s, which was a mixture of tree sap and NH4Cl. That stuff did an amazing job, and the fumes from it rusted adjacent steel as well as eating up lungs.

    2. We have some that smells like someone just smoked a joint of indoor cannabis… I have no idea what flux it is, and where it came from, it seems to be some very old stuff tho.

  12. I switched to lead free a long time ago. It’s hard to find good solder, though. It almost doesn’t exist for hand soldering. I now use Almit Solder with a bit of silver. It’s almost as good as leaded, but I would agree that it also requires a superb soldering station. Below high end Micro-Weller or better JBC or high end Hakko it’s totally pointless. For critical joints I always go back to leaded. Therefore I also think the lead vs unleaded wars are meaningless: everybody can just select the best fit for a particular application.

  13. Love the smell of lead solder in the morning! It is all I use. But i always wondered what is the lead content of the fumes, seems like lead would not float too well.

    1. The guys in the lab were worried about vaporised lead as well, so we did some research. I can’t post all the references, but the result of our research was that there’s no significant vapor. The flux fumes are a bigger risk, so use a fan. But even they aren’t that dangerous. Smoking is much worse. Wash your hands, though, because you don’t want to ingest lead.

      https://www.cmu.edu/ehs/Laboratory-Safety/chemical-safety/documents/Lead%20Soldering%20Safety%20Guidelines.pdf

  14. How many tons of lead extra are there in 50 million tons of electronic waste before and after the stupid change?
    How much less lead is in circulation because of the change?

  15. At home I clearly prefer leaded solder, there’s way less issue with the iron “oxidation” or whatever make solder not flow on the business end. No idea if it’s related to the solder material or due to the highest temperature…

  16. Here in Florida at least, no recycler will accept CRTs with leaded glass, and I have tried long and hard to find one. For years I used to save them and take them to the Waste Management recycling center and landfill 30 miles away. I only recently found out they don’t recycle the CRTs, just dump them in the landfill. Likewise with the circuit boards (and the plastic cases). About the only thing they don’t just throw into the landfill is batteries, and that is only if they are very easy to remove. Boy was I pi–ed when I found that out! Years of having an electronics trash heap in my back yard for nuthin’, and many gallons of gas wasted hauling it. I personally have hauled at least 1000 lbs of lead to that landfill.
    Am I gonna worry about an ounce or two in my solder? Not anymore.

    1. Although there is a lot of lead in leaded glass, little is going to get into aquifers and agricultural soils quickly. It’s embedded in glass which is not water soluble.

    2. First, good for you for spending years hauling all that lead. But, wow! Is Florida’s department of ecology really that messed up? The state I’m from banned dumping CRTs in landfills by law over a dozen years ago. We’ve got recyclers here that actually extract the lead and reuse it. According to our department of ecology, less than 2% of our electronics waste gets sent to the landfill. The bulk of that 2% is particle board from cabinet TVs; no circuit boards, no CRTs, no mercury tubes. There’s plenty of convenient drop off sites or you can arrange pick up. Sound impossible? Not really, we just held the manufacturers responsible since recycling ought to be part of the cost of the product in the first place.

    1. The timing of the melt changes a bit as the flux dries out. Industrially, the expiration date means, “this is how long we guarantee the paste will do what it’s supposed to when you heat it according to the specified profile,” or maybe “if the stuff has been sitting around longer than that, don’t come griping to us because you’re getting bad joints.”

      There’s also a practical limit to the life of solder paste though. After the flux paste dries out, the beads of solder start to oxidize. That reduces the amount of solder available to make an actual joint, and increases the amount of gunk the flux has to try and dissolve. The solder beads have a high surface area to volume ratio, so ‘just a thin layer of oxide’ is a big problem.

  17. Lead-free since rhos was introduced. just squirt some extra flux on the card and the tin flows flawlessly. A good trick i use when doing smd boards is to put them on a hot plate. works better than an oven mostly.

  18. I’m 14, and my mom is super worried about lead fumes so I have to use lead free solder.
    Personally, I haven’t noticed any difference, if anything, it’s easier to use. The temperature dial on my soldering iron fell of, so I could have put in backwards, so I never know what temp it’s at, so I don’t worry about the higher temps.

    1. There’s no issues with lead fumes at the temps your soldering iron allows. It’s the flux fumes that are dangerous and that’s the white smoke you see when soldering.

      Invest in a decent fume extractor with activated charcoal filter and you’ll be right either way and wash your hands after soldering.

  19. I do all my soldering on a bench out in fresh air. A guy from the FDA thought there might even be lead in the fumes. I’m not a chemist.Theoretically fumes might be capturable and reclaimed.
    I hear that the nuclear waste industry is encasing nuke waste in glass.
    wouldn’t be possible to grind all CRT’s separate out the shadow mask,guns,,, melt it down and encase nuke waste inside?

    1. That’s what they’ve been wanting to do, mix nuclear waste into borosilicate glass. This goes back to the late 1970’s before they started digging under Yucca Mountain.

      There was a competitor process to the glass. It was called Synroc for synthetic rock. The waste would be mixed with the Synrock slurry, poured into a corrugated steel container. The containers would be heated red hot in an induction coil then vertically compressed. That would melt and vitrify the Synrock.

      A small scale demonstration Synroc process was built and Synroc samples with a non-radioactive waste simulant handily beat borosilicate glass in all the government’s tests. No breakage, no leaking or leaching of the test material. Just a slight color change after the high temperature water test to simulate geothermal water intrusion into waste storage.

      The government chose borosilicate glass over Synroc. That obvious WTF is part of what’s delayed actually putting waste into the Yucca Mountain facility.

      In 1997, Synroc was tested with real high level nuclear waste. In 2005 a demonstration project to Synroc process 5 tons of waste at Sellafield in England was done. In 2008 a demonstration project was started at the Idaho National Laboratory. Finally, in 2010, Synroc was selected by the Department of Energy as the process top be used for waste processing at Idaho National Laboratory.

      Had the Synroc process been wholeheartedly accepted by all countries as the process for containing non-reprocessable nuclear waste 40 years ago, there wouldn’t be tons of it still sitting around in drums and pools at reactors and nuclear fuel processing plants. But they’re still doing ‘demonstration projects’ as though the Synroc process hasn’t been proven time and again to be reliable and proof against leaching.

      1. I think Yucca Mountain ran into protesters, or something, It’s the “not in my backyard issue”
        Synroc sounds doable , I don’t have ways and means to grind up CRT’s…sledge hammer is too messy.
        What ever happened to that idea of having a mini nuke to power your house? Mar 28 is the 40th anniversary
        of the TMI incident. They ended up evaporating millions of gallons of radioactive water from there. Explains all my extra fingers. I know they guy wrote this here funky song soon after…
        https://www.youtube.com/watch?v=LedxaMGXaj8
        enjoy!

      2. >”there wouldn’t be tons of it still sitting around ”

        Nuclear waste is the strongest argument against nuclear power. If you have a working solution to deal with it, there’s very little reason not to use nuclear power, which is why anti-nuclear lobbyists are trying their best to sabotage any and all attempts. They want to keep the nuclear hazard around, in order to have a point.

        Some would say it’s the tail wagging the dog, but the question of nuclear power is really a question of sociopolitics. They’re really fighting against the idea of anyone having access to that sort of power, because A) it gives you power, B) they aren’t in control of it.

        The Hintergedanke is that if you don’t have centralized big power – fossil fuels and nuclear power – then you have to have some sort of collectivism to manage and shepherd your energy sources which are spread thin and wide. Power to the people! But, it’s the same when you redistribute wealth and economic power such that everyone has access to approximately equal amounts. Nobody really gets enough economic power to do anything individually, so everyone must coordinate collectively. You can’t just set up a factory and start making something – you don’t have the money – you have to go around asking everybody “can I do this please?”, or rather, go to the representatives of the collective authority – the state – to ask for a permission and collective funding because there are no economic equivalents of nuclear powerplants around – no individual rich people who could just do it.

        Likewise for energy, because if the energy infrastructure is based on millions of individual tiny producers which have to be collectively coordinated for the system to work – to have power for anything bigger than a lightbulb – the coordinator of the system gains tremendous power over the society. They have to have it, otherwise you can’t even build it, so the people and groups who wish to become that coordinator and have those hegemonic powers are arguing that no other way will work, ever. It just can’t be a possibility.

  20. It puts the lead solder back and leaves with leadless crap and the cheap stinky flux that has expiration date. F(_)([< Euro trash Pluto haters. 60/40 rosin. 63/37 good and silver/lead for finer work. I'd like to see an honest report on some of gallons(3.8l for euro skanks charging by the liter) of 'new' flux environmental impact. Never got headaches and sinus problems from old shit and vent fan. Cant say the same for new. Is what about needed for reworks- gallons. Then the boards need flushing. No-clean-up versions not very good either. Some of the alloys crystalize and have to grind left over chunkies and chips by hand to save traces.

        1. Not too far from where I write this lies the Silver Valley, a beautiful North Idaho landscape of rugged mountains and low valleys through which the Coeur d’Alene River courses. It looks pristine, but it’s actually one of the largest Superfund sites in the country thanks to decades of careless handling of mine tailings from the hundreds of silver mines heading back into those mountains. Silver is often found in association with galena, or lead ore, and lead was another valuable product that came from the Silver Valley. My neighbor said when he came over Lookout Pass into Idaho from Montana for the first time in the 1970s that it looked like Dante’s Inferno – the trees were stripped bare of needles by the acidic exhaust of the smelters, and the river was a smear of toxic slime. The water was so toxic that migratory geese would be poisoned by the heavy metals, and unable to control the muscles in their necks they’d drown.

          But worse, the children of the Silver Valley suffered the most. Generations of kids were poisoned, and the developmental disabilities caused heavy metals linger to this day. The Superfund cleanup got their homes and schools cleaned – they scraped off the topsoil from every home and hauled it away to dumps – which still leach heavy metals into the river, BTW, although much reduced – and replaced it with clean soil. The river is cleaner, but there are still signs up not to let kids or pets play in certain areas, and there are billions of tons of toxic sludge at the bottom of Lake Coeur d’Alene. The water is clean, and just as long as nobody messes with the muck down there we’re good. Thankfully we don’t rely on the lake for drinking water – we’ve got the Rathdrum Prairie-Spokane Valley aquifer for that, which is some of the purest drinking water in the world. Interestingly, the only reason it stayed that way despite pressure from developers to allow septic systems over the aquifer was due to the same fellow who came over Lookout Pass and beheld the environmental apocalypse of the Silver Valley. He went on to be the health district director and forced the city to build a sewer system to protect the aquifer.

          Anyway, long story, but lead is no joke, and I didn’t want anyone to think I see the lead v. no-lead debate as anything but deadly serious.

          1. It’d be nice if the tailing piles and destroyed landscape around Sumpter, ID were cleaned up. But nooooo! That’s “historical”! Nevermind there’s likely several million $$$ in gold in those tailing piles. When they were made, the dredgers and hydraulic miners didn’t bother with gold dust and smaller flakes. Gold wasn’t worth enough then for the big companies to spend the effort to get every last bit. The little stuff was for the guys with pans and rocker boxes and small sluices. When I was younger I had a talk with one aged fellow who had worked a dredge near Sumpter in the 1930’s. He said they didn’t bother to keep anything under 1/4″ nugget. Anything smaller just went out the other end, but you didn’t dare get caught dipping a hand in to grab some of that.

            Now if someone were to propose a multi-billion dollar federally funded project to do that, with the caveat that *no profit* be made and not a single speck of gold be recovered, then we might see environmental groups get behind cleaning it up.

      1. Fruit Loops. Yup. Everytime one them Califascist no leadys proposition whatever punk ass wet behind the ears dunno jack diddly euro trash wannabe tries to sub out my supplies is same as squatting over my breakfast lunch and dinner. Visions of a rolling vending robot selling recycled food in dystopian future slum housing with its’ vocalized authoritive slogan “Eat re-cycled food. It’s good for the environment and NOT BAD for you.” Still not over Plutos’ demotion either.

        1. Dwarves have not been demoted, they’re worth just as much as anybody else. Stop cyber-bullying Pluto. Pluto is a very special dwarf planet, and deserves your respect.

  21. I asked my board house what kind of solder they used after i did a patch at their place an afterwards realized i had worked with lead free, but didn’t noticed it. So it feels like leaded solder, but it isn’t. Also it contains no silver. Its sn100c – sncu0,7ni sold by balver zinn. Only when i have to solder really thick wires (2mm*2) i feel the difference with leaded solder

  22. The fumes shouldn’t be a metric of quality because you shouldn’t be breathing the fumes. Get a fume extractor. Seriously. I have occupationally induced asthma from too many years of breathing solder flux fumes for 8 hours a day. According to OSHA, this is one of the most common sources for occupationally induced asthma, and I can assure you the cost of a fume extractor is much less than the cost of asthma medication.

  23. you can have my lead free solder when you pry it out of my cold dead hands. besides i still have about 50 pounds of the stuff i “inherited” from my grandpa. none of the new fangled solders work as well. i get better joints with lead and lead soldered pcbs are easier to repair. unless you make a habit out of licking your electronics its completely harmless. lead has kind of been made the scapegoat for a much bigger problem.

    the problem with ewaste isnt that its full of lead. its that we dont have any sane way of processing that stuff. we mostly buck it on down to the developing world so they can melt it down over a camp fire. there has got to be a better way. electronics are chock full of useful resources. anyone who can come up with an environmentally safe way to do that will close the cycle and make the point moot and make a massive wad of cash in the process.

    theres also the attitude that forced obsolescence is a good thing. moors law is pretty much dead in the water and the only significant difference between two generations of iphones is software. then you got electronics full of time bombs that inevitably go off and cripple the device so you go buy another one. hackers fix it, normal people throw it away. and its usually a matter of a couple cents for a better part. good choices at the drawing board and in production lead to a lot less ewaste down the road. but industry likes to choose the path of most entropy because that is more profitable for some reason.

  24. “an electronic waste stream that amounts to something like 50 million tons a year worldwide”

    Beware people quoting numbers. They might just be trying to provoke an emotional response. For example this, we are talking about lead. 50 million tons of lead would be a lot! But what percentage by weight of electronic scrap is lead? Not very much I bet. Most will be the case. Then there’s the fiberglass of the PCB, the individual component cases. And if the device has any moving parts the motors, gears and levers will be the bulk of the weight for sure! If there was 50 million tons of lead per year going into landfills there would be people re-mining them!

    “haywire from the short-inducing whiskers that were sure to grow like weeds from tin-based solders failed to happen. ”

    Yeah. It probably failed to happen because people started throwing everything away and buying new so quickly the whiskers have no time to grow! I remember appliances from my childhood that stayed in the home for decades. Today people “NEED” the latest and greatest every few months. What would do more for the environment? Eliminate all lead use? Or stop throwing away our stuff so early? I think it’s the latter but maybe if we did get that kind of societal change we would all be bit by whiskers and throw our stuff out anyway.

    1. I didn’t say 50 million tons of lead were disposed of per year, just 50 million tons of e-waste. But I found one source that says old televisions and monitors are the biggest offenders of lead contribution, with 4-5 pounds of lead per unit. That mostly comes from the CRT’s lead glass, plus a little from the solder in the PCB. The same source estimates 58,000 tons of lead from e-waste each year. Seems reasonable to me, and it’ll probably decline thanks to RoHS and the decreasing need for CRTs in products. So yeah, the amount of lead as a fraction of the total e-waste stream is small, but 58 kilotons is nothing to sneeze at.

      1. But the lead doesn’t leach out of the glass, except in geological time scale. Even if smashed into chunks and scattered on a beach to be tide worn into smooth pebbles, lead is still bound up in the sediment in non-reactive form.

        As for glass on a beach, California has declared an illegal trash dump as an “archaeologic site”. Look up Glass Beach. For decades people took their non-returnable glass bottles there to chuck onto the pile where they’d break then get churned around by the waves until worn smooth. When soda companies ended their re-use of glass bottles, people threw more glass onto the beach.

        At some point people decided those old worn chunks of glass were neat and started taking some home as a memento of a vacation, some to use in art projects. Some hauled the glass away literally in truckloads. Eventually the rate of removal exceeded the rate of deposit and the amount of glass dwindled.

        So now California has put up signs proclaiming it’s illegal to remove glass from the beach.

        Only in the location that complains the most about human wastes destroying the environment would there be a spot where it’s *illegal* to clean up to restore the original environment. My bet for the most likely reason is because some people were using the glass to make money, and if there’s one thing many environmentalists hate most, it’s anyone making a profit off anything, especially when it comes to cleaning up garbage.

        1. The lead itself isn’t an issue. The question to ask is what compounds does it form in a land fill or simply spread around. It isn’t going to accidentally form the organic compounds that are most dangerous. Over 10 or 100 million years it might form some of the brown dioxides used in storage batteries, maybe some sulfides, maybe even the lead carbonate infamous for white paint pigment. Most lead compounds are not soluble in water. I don’t know the chemistry of the toxicity of lead carbonate but guess it is from hydrochloric acid in the stomach, maybe that is why handling it was not a problem and the danger is associated with children eating it.

        2. Now for the real story: originally these weren’t just spots for dumping glass. They were LEGAL dumps – all types of waste was chucked in the water with the idea that the sea would carry it away. After the dumps were closed, the metals were recovered and sold, the organic waste composted away, leaving just the ceramics and the glass to be worn down to sand by the waves. Some did haul the glass away by the truckload – as part of cleanup programs intended to restore the dump sites.

          The glass beaches became an attraction for the funny jelly-bean pebbles that the tourists pick up, and a source of revenue for the local businesses, so there’s been talks about dumping more broken glass there to keep the beaches from vanishing. The people are actually making money out of the sites by not carrying the glass away.

  25. Kester 44 63/37 all the way! It flows nicely, can set the iron to a lower temperature which means longer tip life, and relatively inexpensive. RoHS is a solution in search of a problem.

  26. I have to use leadfree at work, but use leaded at home. To be honest, I don’t really notice the difference between them when soldering anymore, other then that I need to fire up the iron a bit higher with leadfree solder.

    At home, I don’t really care about what solder I use. I’m okay with both.

  27. Now answer this mystery. Why, without a powerful suction or blowing fan, does flux smoke always flow toward your face? Doesn’t matter where you move in relation to what you’re soldering, the smoke will waft in your direction.

    1. The cancer can smell your fear. That’s why the flux fumes are chasing you.

      Just say something really macho and take a breath, it can’t hurt you for 5 seconds because of the protective field. If you swear a bit and say something hateful about hippies you can extend it to 7 or 8 seconds.

      1. A radiologist at the hospital I worked at always used to smoke while reading X-rays – yes, in a hospital, a doctor was smoking. He always had a lit cigarette sticking out of his mouth, and when he read films with his face pressed up against the big vertical lightbox in his office, the smoke would curl up behind his glasses and over his eye. He ended up dying from a rare cancer – lacrimal carcinoma, or cancer of the tear glands. Pretty much right where that smoke wafted over his eye for hours and hours each day.

        I always think about that when I solder now, and I always say I’m going to get a fume extractor. And yet…

    2. I wonder if it is ions, opposite charges attracting.
      It seems to work the same with cigarette smoke too.
      The clothing/hair of smokers are already de-ionized, so it seeks you out. B^)

  28. I gave lead free a go at home but it required using my 60W iron at the hottest temperatures, it didnt flow well and formed grains/dross too easily. Switching back to leaded gave me much better results.

    I’m sure formulations have improved since then but I really don’t have a strong drive to give it another go.

  29. EE Here. I started out with lead-free and just stuck with it. I think it works great. I can solder QFNs under a microscope just fine, so I don’t know why everybody else says they can’t use the stuff. I always use a high quality iron and solder, so maybe that has something to do with it? Idk.

    1. +1 Finally a decent comment. I had to scroll through all these comments to find one that wasn’t absolutely ignorant. The entire “I have to use lead free at work, but only lead for me at home” mentality screams ignorance. If you have trouble with lead free then you have poor equipment. No other excuse is valid. The rest of these opinions are just idiotic at best. To be truthful, the article itself is mostly a joke as well.

      1. Calling everyone who has a different opinion than you do names is not a winning strategy for getting people to see your side. Praising one person who agrees with you and smearing the rest as ignorant isn’t really productive either.

        The world is nowhere near as black and white as you apparently think it is. Questioning the prevailing wisdom is not ignorance, it’s the exact opposite – it’s the key to gaining new knowledge.

        1. While my post was probably excessively harsh, I take ignorance of proper soldering practices seriously as the internet is flooded with doing things the wrong way under the guise of being a hack. (to be clear, I use the term ignorance in the true definition of the word, not as an insult)

          Reading through these comments fired me up because so many people base there opinions on incorrect data or practices and then readily post their opinions all over the internet. This leaves those looking to gain new knowledge in the dark and absorbing the same incorrect data as facts. I have helped numerous people over the years get past lead-free fears by simply sharing factual data about soldering techniques and tools. I have yet to have one person that did not completely take on lead-free soldering afterwards.

          Soldering lead free takes nothing but proper tools and a bit of following proper guidelines. I’ve been in Electronics Manufacturing for 28 years and personally managed the tools, training, and procedures for lead and lead-free soldering processes. My opinions are based upon years of use, training, experience, certifications, and various challenges overcome across those years. Yes, I have access to very expensive and state of the art equipment at work, but I also do just fine with my lower cost, used equipment at home. I make my own lead and lead-free boards in my garage, both toaster oven reflowed and handsoldered.

          You mention questioning the prevailing wisdom as the key to gaining new knowledge. In the hacker-DIY world, that is many times true as people are looking for new ways to accomplish things that are out of reach due to cost or other factors. The fact of the matter is that the prevailing wisdom regarding soldering is significantly more robust and in-depth than typical.

          I do apologize for my “no other excuse is valid” comment implying that I see the world as black and white. I am one of the most grey world viewers around, but when it comes to soldering lead-free, I haven’t lost a debate yet regarding the fact that lead-free isn’t hard to do at home when done correctly.

          1. The main issue is that RoHS solders all have bigger compromise than lead based solders.

            Usually it’s a choice between being easy to solder, and having good mechanical or physical properties. If you take SN100 for example, or SN99 etc. that’s easy to work with, and you then leave the device you built outside in freezing temperatures – and the tin just vanishes into crumbles. Take SAC305 and it handles just slightly worse – just requires a little hotter iron – but it holds out over a good temperature range, but then you get mechanical failures out of brittleness, etc. If not those, then it’s hilariously expensive and out of reach for the hobbyist. These are real concerns – the devices I build have had to withstand -30 to +30 C temperatures.

            I recently went through the list of different formulations to try and find the most generic replacement for the bog standard leaded solder in our shop, and it was an exercise of Goldilocks and The Three Bears without the little bear’s porridge or bed, and in the end I couldn’t find any that I could actually reasonably source.

            Meanwhile, some of the local shops have gone full retard with RoHS, and the local hardware store offers for electronics repair some alloy that doesn’t even melt until 325 C. It’s completely useless. I guess they don’t have many people buying it, so nobody has told them that it can’t be melted with a regular iron.

          2. I accept your apology,
            but I have been soldering since the mid-1970’s, and it is/was not an easy transition in my experience.
            I had IPI training to get me started on Pb-free, and that helped somewhat. But, even though my employer firmly believes that I have proper equipment (and solder), there are some things that are just harder…
            higher temperatures, workability of the solder, reduced working times. and I find that the Pb-free solder only lets me work with it only once or twice, if I still don’t have the part soldered/unsoldered at that point, the solder just clumps like half set concrete. One of the hardest things for me to remove is a pin-through-hole to the ground plane.
            I have had very little personal success in removing that particular pin and now I turn over the board to a cow-orker to remove it for me. Maybe her irons are hotter or the vacuum is stronger, but whatever it is, she can do it, whereas I’ll end up lifting or damaging traces.

          3. I too would love to see an article discussing the differences between soldering the lead free stuff vs leaded and t he proper lead free technique/temperature, etc. I switched to lead free and I have found it more difficult to work with than leaded. So I know I’d appreciate the commentor sharing his knowledge on this topic.

  30. The biggest joke is, European hunters keep shooting lead into the environment, and it is more than the whole electronics industry used.

    Guess how many of the old white men in politics are hobby hunters.

    1. Americans too. There’s great resistance against lead-free ammunition because it’s seen as a gun-grab: the cheapest unleaded ammunition is basically made of solid brass – some alloy of copper and zinc with additives to make it softer – but that also makes it classify as armor piercing ammunition by another law, so the concern is that by banning lead in ammunition you’re actually banning ammunition.

      In Europe, this isn’t so much of a concern because people simply don’t shoot as much. In the US there’s companies actually mining old shooting ranges for the lead they contain.

  31. My opinion about RoHS and lead in pcb?
    I think a strange thing that EU forbiddes lead in solder that I must use to repair old retrogames, retrocomputers etc, and allows at automotive industry to use massive quantities of lead to produce start battery for cars.
    Lead in old pcb isn’t released on earth if we have possibility to repair it, and to do that, we need lead solder!
    On other point of view, lead free boards breaks more easily that lead soldered boards, so waste and pollution grows more with lead-free tecnology that with “old” lead soldering.

  32. I found a Chinese retailer on eBay a few years ago and bought some reels of 63/37 to keep me going longer than the rest of me will. I also find that if I want to desolder components from PCBs, that it all works a lot better if I first off add a little lead solder to the joint before applying the solder sucker. It means I can run the (homebrew) temperature-controlled a little cooler, which helps prevent tracks from lifting.

    I’m also with a number of other commentators that cold joints are rife in modern equipment, and applying a little real solder does the job nicely – and with leaded solder a cold joint is much more obvious than with lead-free. I do use lead-free solder paste for SMT build and repair, and it never really looks like a good joint to me.

    In the grand scheme of things, the impact I will have on the environment for using lead solder is small compared to the amount used by manufacturers, so I am happy.

  33. I use silver solder because I don’t want my kids exposed to lead like I was. Works fine for me. My dad was an electronics engineer, and I learnt to solder when I was about 8, so I grew up handling 60/40 from an early age. It’s well known that lead is toxic – you don’t want extra exposure if you can avoid it. It’s just the inches vs. centimeters/imperial vs. metric argument all over again, but this time it’s solder. I’ll take the increased flux fumes over the lead exposure, thank you.

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