Solder joints in regular household voltage wiring are not allowed by electrical Code. High current and temperatures weaken the joint and may allow it to separate. Mechanical crimping (Marette nuts, screw terminals etc.) meets Code because the joint will not fail until the wire itself does.
Aerospace applications, especially satellites, use wire wrap wherever possible because it’s impervious to temperature changes. Add in the problem of solder joints growing filaments over time that can cause shorts and soldering is only for the simpler things.
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Look, I’m sure you have meaningfully relevant experience in this field but you’ve got to think skeptically about what you write before you write it. Are you really prepared to say that, on average and under appropriate load, the wire ITSELF will break before your Marette nut or screw terminal will pop loose?
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Sounds like your dad really knows a lot about this.
It depends on the physical and/or thermal stress. The point is - electrical Code will not allow solder connections under normal or high voltage because the solder can’t be relied on to maintain the physical connection. Tested fastening methods and certified connectors are reliable when applied as tested in the certification process.
something similar was used during wwii
They’re used on aircraft too. Wire harnesses that run through a wing need waterproof repairs that still allows the repaired wire to be pulled through a bulkhead via later. A crimp connection is usually too fat. Usually the cable bundles themselves are secured with P-clips so they don’t flop around. Some older aircraft harnesses are more solder sleeve than wire!
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I got nothing. Soldering irons are very good! I don’t see what people have against them.
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I also doubt the heat gun (or butane lighter as demonstrated in the video), actually get the joint hot enough to melt the solder+flux ring and the wires together. Even high-end heat guns don’t get hot enough to melt wires. My guess is that it’s essentially molding the solder+flux ring closely to the wires, forming a contact connection. As long as the joint isn’t placed under much stress or heat, it should work fine. Butt connectors have their place and are great for certain applications, just like soldering with an iron and possibly hot air station.
At a guess, perhaps @willmore meant soldering with both an iron and a hot air station.
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I find they’re quite badly designed for getting at the fillings in my back molars
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Two things. One, a hot air gun is hot enough to melt the ‘solder’ inside of these. Really, I’ve done it myself. There are some very low temperature alloys that easily melt with a hot air gun. To be clear, the wires, pins, and pads do not melt, ever. It’s just the solder that melts between them and forms an electrical connection. Do not ever consider solder to be a mechanical connection. If you do, you’re in for a rude awakening. If you do, you’re heading into what @Carbonman is talking about with the electrical code. Keep in mind that the NEC is a condensed form of knowledge meant so that “monkey hits the button” level people can get things right if they follow the rules. Trying to work backwards from that is just looking for trouble. It’s better to understand why the rules are rather than to try to guess why they are.
The second thing is yes, actual hot air soldering. SMD rework is done mostly with hot air. They look a lot like a soldering iron, but they have a little nozzle at the end which blows out hot air. Both temperature and flow rate can be adjusted.
For traditional through hole soldering, you heat each connection individually to get the solder to flow between the part and the board, but with SMD soldering, you have to stop thinking in those terms. You solder whole packages at once–all the leads and pads all at the same time. You use wide area, uniform heating. There’s a reason that large scale manufacturing takes place in huge ovens. Whole boards are soldered all at once.
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What I mean is that a hot air gun isn’t going to melt the wire with which the solder is supposed to bond. Am I incorrect in thinking soldering with an iron forms chemical bonds between the solder and the metals to which it’s applied?
Apologies, merely a hobbyist when it comes to soldering. My very possibly incorrect understanding is that solder forms a chemical bond with the metals it connects, whereas welding forms chemical bonds directly between the crystalline structure of two metals.
But the surface of the metal being soldered has to melt to form that bond to the solder? And a heat gun can’t reach that temperature?
But quite possibly I’m wrong; maybe solder doesn’t actually form a chemical bond with the metals it connects together?
Yup, that’s what I figured you meant. Rework station is the other thing I’ve heard a soldering iron plus hot air station together called. If I may ask, what’s the difference between ordinary soldering with an iron and a full-fledged rework station. Is it just having enough heat on the PCB or other surface to melt the existing solder-to-connector bonds?
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To start with, I am by no means an expert, but this is related to a field in which I’ve worked for several decades and I’ve had the good fortune to work ith people way smarter than me and I think I may have learned a few things from them and that’s what I will try to share.
There are three related terms: soldering, brazing, and welding.
Soldering is using a filler metal to, well, fill the gaps between two other metal pieces. Brazing is pretty much the same, but uses higher melting point metals as the filler. One functional difference is that soldering isn’t meant to make a mechanical connection whereas brazing is. This is mostly due to the differences in the filler materials–the lower melting point soldering filler is weaker than the harder, higher temperature melting brazing filler.
The last one is welding. That takes two pieces of metal and melts them to form a combined piece. Neither brazing nor soldering do that. With welding, you have part A, a melted AB mixture, and part B. With soldering/brazing you have Part A, filler, Part B.
I’m unsure of how you mean to be using ‘chemically’ in your post, so I can’t really address that.
So, it’s completely practical to use hot air to melt ‘solder’ to connect two pieces, but brazing and welding require way more heat than is practical to be carried by air.
I rework station is named that way because of its intended use–to remove parts and to replace them. It may be identical to a ‘soldering station’, but it’s just named after its intended use rather than what it is. Like calling an air pump a ‘bicycle pump’. There’s nothing requiring it to be used only on bicycles, but that was the intended purpose, so that’s what they name it. It won’t stop you from filling up a basketball with it, though.
For through-hole, a rework station will have a vacuum pump to suck out solder from a junction. But nowdays most rework stations are meant for SMT and that’s just a hot air tool for both part removal and resoldering of the replacemen part. So, maybe ‘rework station’ has suffered a bit from a change in the surrounding technology.
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I think when you say mechanically it addresses what I meant by chemically. Again, apologies for my amateur terminology. I had always thought soldering formed a crystal between the solder and the metal surfaces being soldered together, but now I’m thinking that was an erroneous belief on my part.
Very clear, and thank you. Also, thank you for sharing your knowledge. Sharing knowledge and experience is one of the best parts about the Boing Boing BBS.
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Never apologize for not knowing something, I wasn’t born knowing this either. I just had the good fortune to run into people who did and some of it rubbed off onto me. If I can do that for others, than that’s great. I hope they have a chance to do that for others as well.
That’s what I had always thought, but I see way to much groupthink and social clubbing and it worries me about the future of BB’s BBS. All I can do is to work to make it better by not being like that. And maybe by bringing attention to it. But I’m getting off topic, so I’ll stop.
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Well, this is a handy thing I was not aware of. It will make connector changes much easier for me on my RC ESCs and batteries. Thank you @frauenfelder
I’d be careful using these for high current connections. The low melting point solder in them will fail if the wire heats up. As long as the props can keep a lot of air moving over the connection, you might be okay, but I would be very nervous putting a lot of current through one of these. The though of an RC’s batteries shorting out because of a connector failure haunts me.
Please stick to crimping your high current connectors.
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FWIW, the Boing Boing comments forum has, in its various incarnations, been my Cheers for well over a decade, and lurking for fifteen years. It has something for everyone, but not everything is for everyone. There’s definitely a strong community, some of which goes all the way back to the original zine before my interest in Cory’s science fiction led me here. But the best part for me has always been that I can both share my own knowledge and learn new things both from the wide array of smart commenters and the things that get posted. There are absolutely topics I skip over because I know they’re not for me, but enough that’s left that I love interacting with the people here.
In the end, every day for me is a chance to learn more, and here I learn more than enough to keep me coming back. 
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Both welding and soldering create alloy between workpiece and filler metal. While with soldering temperature is not high enough to melt the workpiece, filler metal still dissolves a bit of the surface, creating an alloy. The funny thing is that locally created alloy can have melting point that is lower that melting points of both filler and workpiece:
The extreme example of liquid metal with lower melting point dissolving in solid metal can be seen when mercury gets into contact with aluminum:
https://www.youtube.com/watch?v=Z7Ilxsu-JlY
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If my hands were as shaky as Mr. Ragan’s, I’d be looking for an alternative to a soldering iron, too…or back off the caffeine a bit.
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