Here's real soldering the Tektronix way.[1] This is the soldering technique for Tektronix ceramic terminal strips, which had silver fired into the surface of the ceramic. The solder used was 3% silver. The innards of Tektronix scopes of that era are just beautiful.
Tektronix was the first to make oscilloscopes where the screen was calibrated, and you could measure voltage reasonably accurately. Earlier scopes just let you see the general shape of a waveform. So Tektronix had to develop components and techniques to make electronics behave consistently, over a wide range of temperature and humidity, in portable instruments.
Curious if anyone has tips on lead-free soldering. I basically always see in online forums "just use lead," but never any tips on how to actually become capable on using lead-free solder. Esp. as my son is around a lot, it seems prudent to stay lead-free, even if you can generally handle lead safely. Thanks.
Depends on the components. You need to get enough heat into the joint that both sides are hot (pad and component) but not enough that you burn up a sensitive part. The hack people use, wetting the joint with solder by touching it to the iron can lead to a cold joint. Don’t do that.
Turn your iron up (I use 675) and ensure you’re touching the pad first, it’s a much larger heat sync. Lean the tip of the iron up to the component leg, give it a second and then feed solder into the other side of the leg, letting the leg of the component melt the solder and flood the joint. I use flux if I’m really worried about the joint, the fluid transfers heat better. There should be a clear fillet arcing between the pad and leg of the component, solder should be wet 100% around the pad and gracefully blend into the component leg. The joint should not look sandy or dirty or have bad surface finish.
Just use Metcal fixed induction soldering irons. I just saw a power supply for an MX-500 for $100 on eBay and there is the hobbyist level PS-900 on sale new for under $300 on Amazon right now (which works just as well but might not last 30 years like an MX-500). Thermaltronics was started by some Metcal engineers after their patents expired so they’re a cheaper source of tips but I haven’t looked at their power supplies recently.
Unlike wellers and other soldering irons they don’t use a PID loop. They exploit the curry effect of the alloys their tips are made of and pump 2.6 MHz RF into the handle which keeps the tip heated the entire time with zero delay, even when contacting huge copper pours. The downside is that you have to change the (expensive) tips to change the temperature, but the upside is that it’s capable of delivering much more heat. Since the iron is capable of heating so fast, temperature control doesn’t really matter because it can melt the solder long before damaging nearby chips.
If you’re not using a solder oven, that’s the best option. It’s expensive but it’ll make a night and day difference to your soldering work. I’ve got a Metcal that’s almost 25 years old that still runs like a champ, is compatible with tips sold by Metcal and Thermaltronics, heats better than any soldering iron I’ve used since, and is easily repairable if it breaks.
The MX-500s have a design misfeature where power is constantly on internally. The switch only controls the output driver to the handpiece. Put these on a switched circuit for part time hobbyist use.
Leaded solder is not a big health risk for hobbyists as long as you have proper fume extraction. Metallic lead is poorly absorbed through the skin (it _is_ absorbed from what I can find, but very very slowly), the major risk is from lead vapour and at normal soldering temperatures that’s very minimal.
However, lead free tin-silver-copper (SAC) solder is fairly easy to work with. You need a hotter soldering iron at around 300°C, and if soldering PCBs preheating the board to 80-100°C may be needed for good results. It may also take a bit longer for the solder to propagate flow and wet, since the surface needs to be hotter.
If you’re using additional flux or non-fluxed solder you’ll need to check it for compatibility, that should be on the data sheet. Most fluxes are fine, but I’ve seen a couple that say not to use with some lead free solder formulations.
The main downside to SAC lead free solder is the higher temperature required which can overheat some components, particularly capacitors and ICs in my experience. It’s a case of being careful to keep the heat duration as short as possible.
Personally I went back to lead solder and manage my exposure with ventilation and HEPA filters.
One thing I didn't see brought up in the sibling comments about vapor is that the real hazard of using leaded solder is small particles which can end up on clothing or your hands and later ingested. It is definitely a hazard to be aware of, you want to wash your hands after working with it and keep your workspace cleanliness in mind.
For hobby work, I've switched to lead-free simply because that's what 99% of the boards I work on we're originally soldered with, but I still have some leaded solder around. That being said, it can be used safely, I cast my own bullets which generates a far larger amount of lead particulate and my blood lead levels were not at all elevated when I had them checked 2 years ago. But since it bioacumulates, you do want to keep exposure in mind.
Good point, I totally forgot that because cleaning my workbench and hand washing after work is just second nature to me now.
Metallic lead is dangerous if inhaled or ingested, but not a big concern for momentary contact with your skin as metal, especially given most modern solder is only 40% lead.
Your body will remove a small amount of lead, so hobby soldering is unlikely to cause long term problems.
I cannot imagine anyone soldering with SAC at 300ºC. Not even leaded solder with pre-heating as merely an option. But somehow those values crop up from time to time.
I'm not going to debate them though, I'll just dump my values, it might help someone.
My job involves soldering at least once a week from through-holes to SMDs(mostly), 1.6mm to 0.8mm pcb thickness, from 1206 smd to 0402 (imperial) sizes. From flimsy 0402 resistors to beefy 1cm² all metal casing inductors from hell.
To do all this I use a JBC soldering station with C245 and C210 tips. I also use a non-brand hot-air station for TSSOP ICs with exposed pad on the underside for heat transfer. Sometimes I use a hot-plate as well, and a reflow oven while we're at it.
On the JBC:
For leaded solder: 350ºC on both C245 and C210 tips. I do increase it to +/- 360ºC on occasion to solder near big stubborn ground planes on the pcb. Less than that is impossible without pre-heating because I can't afford to spend more than a few seconds on each soldering op, both because have other things to do and because I can't overheat components. Overheating is also dependent on the time you spend on each component. Might bump it up to 380ºC on those inductors and switch the tips to beefier ones like the chisels and the knives.
For unleaded SAC: 360ºC to 380ºC on those same tips, and I might bump it up to 400ºC again on those inductors.
On the hot-air station:
For leaded: 275ºC
For SAC: 282ºC
On the hotplate: 240ºC for both SAC and leaded. (Mostly repair work after pcbs come out of the oven.)
On the oven: It's a temperature curve and I only use leaded solder paste. Peak at 240ºC.
NOTE1: All the soldering wire I use is flux cored. I tend to use extra flux a lot (Chipquik SMD291), even if it's not really necessary. But on lead-free SAC it's always obligatory.
NOTE2: We don't have any fancy setup where I work and it's overall barely professional in my opinion. Pre-heating is not used much if at all so, I don't have any temperature values to share in that regard.
NOTE3: The SAC solder wire I use is Sn99Cu0,7Ag0,3 EVO11 from CYNEL. I like the brand but I feel the need to try other formulations for different use-cases so I can get away with using lower temperatures on specific temperature sensitive components. On leaded I don't feel that need at all.
I've heard that the soldering temperatures aren't nearly enough to make the lead a gas and the fumes from the flux are what can kill you. I suppose the same advice applies in that case, but is that accurate?
Yes that’s accurate for hobbyist work. There will be some lead vapour, but at the temperatures used for soldering we’re talking a few atoms. The flux is much more of a risk, and both are mitigated with proper fume extraction.
Lead does bioaccumulate so continual exposure to low levels is dangerous, but unless you’re soldering all day every day it’s not likely to be dangerous.
If you’re a factory and have multiple wave soldering baths operating it’s a different story.
Lead has a boiling point of 1749 degrees C. That is at least 1200 degrees higher than your typical soldering temperature. If you use a propane torch you’ll almost touch that temp.
Correct, but all materials have a vapour pressure so there will be a very small amount of lead vapour when soldering. Based on lead’s vapour pressure it’s in the range of a few atoms, I haven’t done the math though.
I mentioned it for completeness because someone else would if I didn’t.
Quick math shows that vapor pressure of lead at 500 degrees C is 1/7,600,000 of an atmosphere. I don’t know how to calculate the rate of sublimation but this does seem pretty negligible.
Do you know how dangerous new vs old flux is? I'm using some old Канифоль from the USSR and get headaches while soldering. Fume extraction would probably be a good idea, but I solder no more than 4h a year
There is a technique where you breathe out as you solder. No idea if канифоль is toxic or not but honestly if it gives you headaches why not try another type? Or wear a respirator?
1) board preheat. In a pinch, heat gun or old hairdryer. But ideally get a cheap ceramic one off amazon or something. Typically set it to 75C for delicate components. For sturdy boards i start there and if that still sucks you can usually go up to ~150C. Usually its the heating element or air temp not the board temp.
2) Flux and thin solder. Solder should contain flux too. Use solder paste whenever possible and keep it refrigerated when not in use as it dries out
3) you need a high wattage iron and usually a thicker tip with more heat capacity. A slightly higher temp helps a little, but the wattage helps it stay a consistent temperature from the start to end of the joint.
4) when designing boards use ENIG and not HASL
5) remove any old solder before attempting to add more to a joint (older than a day or two).
6) sometimes an air gun on a arm helps too on thick copper
7) get really good lighting with a mix of diffise and directional sources. Brighter than you’d think
I'm hardly an expert, but when I switched to lead-free solder (for the same reason, had a young kid around), the only change that helped me was soldering at a significantly higher temperature. The lead free stuff still doesn't behave quite as well as the leaded stuff -- hey, lead is useful! -- but I do feel a lot better about my garage. Though I did backslide when I had a project that required about 500 manual solder connections; after a few days of frustration I guiltily went back to lead, briefly.
Ditto. I switched to lead-free for custom keyboards and it didn’t seem too terrible, just had to dial in the temperature more closely to avoid damaging components.
As a child who was taught how to solder (Thanks Dad!) I can say this: making the practice of post-solder handwashing just A Thing does a lot to impart good practice.
if you're super paranoid, D-Lead hand soap is a fantastic product: https://esca-tech.com/product/d-lead-hand-soap/ -- I use it post-shooting to wash my hands of lead and residues from firearms.
Don't equate solder to (liquid) metal touching other metal. Soldering is a chemical reaction between metals, and it needs a pretty high temperature for that to occur. The solder simply touching the other metals isn't enough, those are commonly called cold joints, because the chemical reaction didn't happen, only the mechanical melting and freezing did.
The higher temperature is the main source of difficulty: it can be harder to heat up a joint to the right temperature without overheating the iron tip or the components. So it's mainly a case of getting good thermal contact between the iron and the joint, and having a powerful enough iron and the right size tip.
(One trick that can be very helpful is pre-heating: e.g. placing a board on a hot-plate at ~150C or so, or using a hot air gun to do the same. This means the iron doesn't need to heat a much. But of course this makes placing and holding the components more difficult)
Use a higher temperature and plenty of flux (I like flux pens), and you'll be fine.
Leaded isn't actually a significant health risk for you, so you might as well go with that. It's not like you are going to breathe in lead. It's a problem for the environment in general, and you do not want to consume it, but it isn't that unsafe. A bigger problem is that you should never use leaded solder to repair boards that have been soldered with lead-free, which means pretty much every board out there that has been manufactured in the last 20-30 years or so.
I agree. The rosin/flux comprises the majority of the fumes. It's still a good idea to have ventilation.
I have a setup in my garage with a vent fan connected to a dryer vent and a rubber flexible hose I can put near the solder station. I also hook it up to my 3D printer enclosure if I'm doing ABS.
It's really OK. With modern formulations such as SAC305 and with temperature-controlled stations, there's no real difference, and no need to stick to lead.
I think the resistance to the idea has two roots. First, there's a lot of old-timers who just didn't like the idea of the government meddling with their hobby, so they go out of their way to convince others to use leaded solder.
Second, the first years of the switch were painful. You needed to upgrade some equipment, the early alloys were not performing great, there were problems with tin whiskers (which aren't specific to lead-free soldering, but were apparently happening more commonly), etc. But these days are gone. The industry has moved on.
I will say, you need to use high quality lead-free solder when you could get away with decent lead solder. The cheaper lead-free stuff has been junk in my experience.
Do you have any recommendations? I was soldering earlier today and noticed a particular joint wasn’t flowing well at all. I looked over and had grabbed the lead-free solder from my spool holder. All the other joints with my crappy Radio Shack leaded solder were fine.
I don't. I have a roll of lead-free that works OK, but I got it so long ago that I don't know. I think it's an off-brand that doesn't even have a name on it, or the sticker peeled off. It's still more temperature sensitive than lead, but not bad. I think my better quality lead roll is from them too. I wish I knew the name so I could order more of each.
On a related note, I've had terrible luck with any of the Chinese solders off of places like Temu or Banggood. Even the lead ones were junky.
Chipquik works fine. There’s probably better stuff but it is consistently good and doesn’t seem to go bad (i can’t tell much performance stuff between a roll that’s old enough to have the label rubbed off and a brand new one).
The government did not meddle with the hobby, though. You, hobbyist, can acquire and use as much lead as you want. You can order an 4kg bar of 60/40 lead solder on the internet right now. That's enough lead to measurably lower the IQ of 15 million children, if optimally applied. Nobody will stop you.
I use lead free solder and haven’t had issues though admittedly I have been soldering as an amateur for decades. You want flux and higher temperature. That’s about the only adjustments. It goes without saying that you should use clean tips and a quality iron.
Don't forget that many of us grew up in an era when leaded gasoline was widely used, and if anything the population today does not seem any smarter, so whatever effects leaded solder has is going to be miniscule in comparison.
I suggest practicing on perfboards, TH and SMT. Chipquik has boards for about $2 each. Compare different solders (SAC305, K100LD, SN100C), temperatures, pad sizes, fluxes, etc.
I learned to solder electronics using my father's giant Weller soldering gun. 40 years later I was visiting and had to repair a tiny connection on an electronic candle. I felt like Captain Caveman wielding that giant humming pistol with the lightbulb illuminating the work but by cracky I could still do fine work with that monster tool.
This was the longest video I have watched on Youtube in ages. The lack of intrusive ads was refreshing.
When I was in college I worked as an "electronics technician" intern for a few months. We would work through 3-10 page mods to update PCBs from one version to the next. We worked under a scope, and sometimes routed magnet wire all the way across the board, or even thru vias from one side to the other.
It was painstaking work; I had a coworker friend who was a true artist. I never got that good at it, but I sometimes miss that kind of work.
It's more likely that your iron is under powered for your application, and frankly a copper tip will likely make the problem even worse. There are three dimensions that impact heat transfer (temperature being equal): Thermal mass of the tip, thermal conductivity of the tip, and power transfer to the tip.
If your iron cannot support a regular tip, it's likely that it cannot get enough power to the tip to sustain the heat being pulled from it (copper will just expedite this). You can try a beefier tip (or load up a tip with wet solder which can kinda give the same effect) or you can get a higher power iron.
I've been soldering for 15 years with all manner of irons, I've never needed a copper tip, but I often need more than your standard hakko or weller. 400C on a the hakko is not at all close to being equal to 400C on a Metcal for instance.
When the tip is tinned effectively though, my Hakko works fine. The problem is keeping it properly tinned is a damn challenge: i.e. I think I wiped the whole thing on a sal ammoniac block, then rosin flux, then put the whole tip into a solder bath and got...a tiny spot on the tip which has remained reliably tinned and is the one spot which works well.
The symptoms are pretty obvious: even if the iron was underpowered, melting a thin piece of solder wire should be pretty much instant. My issue has just always been getting the tip to a shiny solder finish with all the recommended tools...just doesn't work once that iron layer oxidizes initially.
EDIT: Although thinking about this now, actually the way you get rid of mill-scale is with white vinegar so maybe that's my actual answer: white vinegar for a couple hours, then rosin flux and then into the solder bath. Hopefully won't remove the entire iron coating on the tip since otherwise...copper tips again.
I had a tip like this once. I ended up getting an old flat blade screwdriver and running the sharpish edge of it up and down the tip to remove the baked on crud, until I could see the dull shine of the plating all around. I then tinned the tip using flux bearing (electronics) solder and repeated until all the dry bits on the tip had gone and the tip was fully tinned. It seems to have been okay since then (quite a number of years).
I wouldn't want to do the above too often and it's probably not the recommended way, but I seem to have gotten away with it by not being too rough with the screwdriver. Potentially worth a try if the tip is a write off otherwise.
Once it is tinned, clean and tin the tip before turning off after every use (but you probably already know that).
It sounds like maybe either you're doing something wrong or there's something wrong with your iron. I have a Hakko and it works great, I have no issues with tinning the tip at all, never had to do a vinegar soak or anything like that.
You probably have a shitty soldering iron which can’t deliver heat consistently. Try grabbing a used Metcal PS900 or MX500 on eBay. I have done zero maintenance or tinning on either of mine. They just work. I do SMD and TH stuff and rework no problems at all.
Literally everyone who gets one goes “oh so that’s what soldering is supposed to be like”
Also might be crap solder. Get some decent Felder or Multicore stuff. Leaded is easier to work with and harmless if you wash your hands and don’t lick your PCBs. Silver bearing leaded from Felder is what I tend to use. But it’s about $70 a roll
Edit: I see that you have a Hakko. Buy genuine tips. Or replace it with a different iron. The cheaper Hakkos are terrible.
Interesting. My experience is the opposite. Sodder, soddering is the norm. Every lab, every tech at every company has said it that way. I'm from the west coast USA if thats relevant. If I ever heard someone say "sold-er" I probably dismissed it as someone who only ever read the word, and was sounding it out phonetically.
I would love to play around with electronics but I hate soldering. I hate the toxic smell and fumes, I hate the small bit of metal shards that seem to go everywhere. It's been 100 years since electronics, why no soldering alternative to make connections?!
Use a fume hood or extractor and really learn how to solder properly. It sounds like you are either running your iron too hot and/or you are trying to melt your solder on the iron and pass it to the joint. The pros use a TON of flux because it practically solves the oxidization issue and helps a lot with spreading the heat to where you want it to go. Half of your temperature issues can be solved by either preheating your boards or spot heating with a hot air rework tool.
Soldering makes a metal-metal connection, with the flux ensuring oxides are removed. This makes a very low resistance connection, mechanically it’s very strong, and it’s easy to automate. As a bonus it’s also very easy to undo.
Other technologies like glues and crimping have their uses but are less reliable, higher resistance, or difficult to automate.
This may change but there’s little demand. Glues have lower conductivity and are harder to remove, mechanical connectors are bulky and not as strong.
Tektronix was the first to make oscilloscopes where the screen was calibrated, and you could measure voltage reasonably accurately. Earlier scopes just let you see the general shape of a waveform. So Tektronix had to develop components and techniques to make electronics behave consistently, over a wide range of temperature and humidity, in portable instruments.
[1] https://www.youtube.com/watch?v=RpB5JqGo1co
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