Okay, okay, after my first few times working with lead-free solder, specifically 99.3% tin, 0.7% copper, I’ve come to some conclusions. Yes, this solder is indeed reasonably workable under the right circumstances… it is harder to wet… but most of all, the higher melting point makes it so much harder for me to get it to melt, flow, or stick to the soldering iron at all! Yes, I’m still using my cheap fixed-temperature Radio Shack soldering iron, 750 degrees Fahrenheight. Surely due to Newton’s Law of Cooling and the like, a higher iron temperature is necessary to compensate for the fact that it takes longer to heat up and it the cooler surroundings cool down your parts faster.
So, let’s go searching the Internet, what do other folks recommend? Ah, they actually recommend doing the same as for leaded solder! 400 Celsius, 750 degrees Fahrenheight for a small tip or low-effect soldering iron. A large tip or high effect soldering iron, you don’t need such a high temperature.
20200828/DuckDuckGo tin 99 soldering iron temperature
20200828/https://www.build-electronic-circuits.com/right-soldering-temperature/
20200828/https://www.quora.com/What-is-the-correct-iron-temperature-to-solder-with-99.3-tin-0.7-silver-solder?share=1
So, I guess if I want to go lead-free, bismuth solder is the way to go for the lower temperature. But, well… now there’s some complications if you use that long-term. Bismuth, despite being fairly non-toxic to humans, is actually a rather rare earth metal, only twice as abundant as gold. Worse yet, bismuth is extremely difficult to recycle, all current means are un-economic so the metal simply isn’t recycled. That means that although bismuth is cheap and abundant today, it won’t be in the future. That’s also really too bad since bismuth-based solder uses bismuth in a majority role rather than a minority one. At least it’s less toxic than Indium.
20200828/https://en.wikipedia.org/wiki/Bismuth
20200828/https://en.wikipedia.org/wiki/Indium
Well, I guess that means I must confine my nifty whole-board lead-free reflow soldering with through hole header components to prototyping only. Not recommended for production, not even recommended for kit builds unless you’re targeting total novices. If you want to go lead-free economically, you’ve got to go high temperature.
Okay, okay, now here is the low-down on what’s going on. Sure, I know I messed up on a number of counts leading up to this.
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I didn’t want a desoldering pump so I opted to use solder wick since it can be used with your soldering iron. But, solder wick especially has a prospensity to wick away your tinned tip to an untinned tip. Nevertheless, solder wick is essential for fine-tuned cleanup, desoldering pumps are aimed at coarse and blunt work.
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There were many times when I was not skilled in applying solder and had to use solder wick a number of times, accelerating the solder wick problem.
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Given the issues with using solder wick, I should have had wider diameter Rosin-activated flux core solder at my disposal. Alas, I did not because I did not want to use such strong fluxes (I picked no-clean flux, I didn’t want to have to clean it either), and I thought using thinner diameter solder wire would make soldering small joints much easier. Well, I was right on it being easier to use with small joints, less worries with thrusting in too much solder wire and getting too much solder on your joint. But when you have absolutely no thick wire available, tinning your full tip takes that much longer. And you do not have that time when your tip is oxidizing. Plus, no-clean flux will be too mild to help keep your tip clean when this happens.
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Due to the difficulty of keeping paper towels wet, I was sometimes wiping on dry paper towels, and also sometimes paper towel fragments would get stuck to the soldering iron tip and burn leaving impurities.
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I waited too long to get tip tinner/activator and my soldering iron tip has some spots that were too badly burnt for the tip activator to bring them back functioning. And now I don’t want to use the polishing bar, emery cloth, or or soft steel brush that would be the next step required.
Well, all that mentioned… indeed, if the temperature is adequate for lead-free soldering, and the recommendation is to not go higher than the temperature I have as that only greatly accelerates tip oxidation, then the only other path to make such soldering easier is to use a bigger tip. Or… yes, the equivalent I was getting at, get as much tip surface area as clean as possible, so as much of the heat that the soldering iron puts out on the tip is readily available for conduction to the point where you are applying lead-free solder.
20200828/DuckDuckGo how to solder tin wires
20200828/https://forum.digikey.com/t/how-to-clean-tin-and-maintain-soldering-iron-tip/2006
So, well, all that said about soldering iron tips and the lessons I’ve learned, are there any other tips in particular on how to tin wires in general? Well, here are two articles, they don’t really provide much info out of the ordinary. Tin your iron, touch your wire to your iron to get it heated up first, then touch your solder wire to your wire to tin it. One thing I must advise against, holding your fingers close when tinning wire tips. This is not good for safety.
20200828/https://www.thespruce.com/tinning-stranded-electrical-wires-1152893
20200828/https://www.instructables.com/id/Strip-and-Tin-Wires-Like-a-Pro/
Okay, so I have to verify. Is steel wool a suitable substitute for using a soft steel brush to clean off bad oxidation? Yes, it is acceptable, again so long as you use the softest/finest possible steel wool, just as you need to use a soft and fine steel brush. It should work pretty well to get the bad oxidation off the metal surface and get a nice shine.
Do not take the alternative approach “if you don’t have steel wool” of using wet and dry sandpaper of the finest grit. Of course you want to be as fine as possible to avoid scarring and ruining the soldering iron’s plating, but just don’t even do this as there isn’t any justifiable reason unless you have a very worn out tip.
20200901/DuckDuckGo steel wool polish corrosion off soldering iron
20200901/https://electronics.stackexchange.com/questions/398336/can-i-use-steelwool-for-soldering-iron-cleaning
20200901/https://www.doityourself.com/stry/5-tips-for-cleaning-a-soldering-iron
This is also a good discussion here. Worthy of note, lead-free soldering requires much more frequent use of tip tinner/activator than leaded soldering. Yes, because with the higher temperatures required for lead-free soldering, it’s that much more important to get optimal heat transfer, not to mention that oxidation happens faster at the higher temperature.
20200901/https://electronics.stackexchange.com/questions/371836/wet-sponge-or-brass-sponge-for-solder-tip-cleaning
Oh yeah, another point for soldering. There was one retrofit wire in particular where I had a really hard time soldering to it after reworking it a few times. Was it just a copper-plated aluminum wire? That would most definitely be it if that was the reason why it became almost impossible to solder to. According to the Digi-Key tech forum post, “if [copper is] exposed to solder, it will quickly dissolve into the solder.” So, lesson learned, be especially careful with these wires? Apply the solder correctly the first time or else dispose of the wire and replace with a new one. Once you start working, the solder will start dissolving the copper off the surface, and if you end up removing this solder and trying to reapply it, you will not have any copper surface left to solder to.