94.5% lead solder dangers? - Page 1
Forum section: electronics / general

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 02, 2018, 11:37:47 pm
content: I bought some really thick solder for when I need to solder large wires together, I have a project coming up that will involve #6 and even #2 wiring (solar project) which will I figure might go better with a heat gun or torch.I did not realize this solder was that high in lead though as I was paying more attention to the thickness when buying as I wanted to thickest I can find. (already have thin solder for actual electronics work) . Is this something I should worry about health wise, like even when touching it? I don't tend to be too concerned about typical 60/40 but this is quite high. Or is lead danger in general over exaggerated? Obviously I will be doing my best not to breathe in the fumes, but is this actually getting into mask territory?

author: Halcyon
author_rank: Unknown
timestamp: October 02, 2018, 11:42:53 pm
content: The fumes aren't your problem, just wash your hands thoroughly after handling it and don't stick it in your mouth.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 02, 2018, 11:49:19 pm
content: Apparently flux fumes are the issue. The lead doesn't get hot enough to vaporise. Lead is dangerous when ingested, so be sure to prevent that. Note that washing your hands with water and soap doesn't very effectively remove lead.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 02, 2018, 11:53:32 pm
content: Oh, gosh, so, high-melting solder, almost pure lead?Not sure why you'd need/want to solder wire with that, you can if you want to I guess. You are much more limited on fluxes, though: rosin carbonizes rapidly at that temperature, and even acidic options start to run out (though I think zinc chloride is still fine -- if you can get it anhydrous, which is a bit more difficult however!), not that you necessarily want to use them.Hmm, I'd be willing to bet hydrolyzed beeswax would do well. Maybe it hydrolyzes/pyrolyzes enough as it is -- it's often suggested as a flux or cleaner of molten lead. Seems doubtful that it would be reactive enough to clean copper metal, though.Is that even a good idea because of insulation? You'll burn even PTFE up there (stay out of the fumes!!), let alone anything lower-melting. Polyimide is still okay as long as you don't dwell too long, but it makes notoriously* poor insulation in general. That leaves... uhm, heck... fiberglass-served wire?? Good luck with that?! (Not impossible -- silicone-impregnated fiberglass sleeving is a standard product, and high temperature thermocouple wire comes wrapped with fiberglass.)Obviously(?), the standard approach is lugs and terminals, for all these reasons and more; I'm more curious why you aren't pursuing that approach? (Renting a crimp tool for a few days isn't going to kill you, especially if you've already spent the money on wire that beefy!)*Blink*, ah, so to actually answer your question: no, absolutely no risk whatsoever. Don't lick it, don't breathe the soldering fumes (the smoke from whatever flux is put on top is both the more acute and greater hazard), and wash your hands when done. Solid lead particles are not absorbed by the skin (you'd have to go rather out of your way to find something that is -- hmm, TEL comes to mind), and honestly even ingesting the particles isn't as high a risk as you might think -- still definitely a risk, but the retention rate for adults is surprisingly low, around 10%, meaning you need a 10x higher dose for the same risk factor (absorbed bone dose) as a child has (absorption 50-90%!). Basically if your bones are growing, be extra careful to avoid lead; otherwise, take basic precautions like dusk mask and washing.Tim

author: coppercone2
author_rank: Super Contributor
timestamp: October 03, 2018, 12:18:41 am
content: Look up the vapor pressure tables for lead to get an idea of whats going on when you melt it.Cadmium is particularly nasty.the lead you got might be for welding roofing material together (like with a gas torch, like welding with other metals), to make a water tight roof.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 03, 2018, 12:27:54 am
content: It says it's for electronics, but was definitely not my intent to get it at that high a percentage, was not paying attention there. I'm not even sure how well it will flow tbh, I will have to play around with it I guess. My intention is to attempt using a heat gun or torch. I never heard of anyone using a heat gun but I imagine it will basically be like using an 1500 watt hot air rework station.Ideally I will be able to heat the wires then touch the solder and it will melt and flow immediately but I'll see. I've done copper soldering so I presume it will be somewhat similar. I was going to actually use plumbing flux and solder but from what I read that's a bad idea for electrical.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 03, 2018, 12:43:02 am
content: What electronics uses high lead solder, especially with RoHS banning lead from almost all electronics?

author: helius
author_rank: Super Contributor
timestamp: October 03, 2018, 12:45:16 am
content: The primary danger of using Pb94.5Ag5.5 as an electronics solder is destroying your electronics. It has a liquidus of364°C: does your soldering iron even go up that high?

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 03, 2018, 01:43:31 am
content: This won't actually be for electronics, more high gauge electrical wiring. Need to splice some #6 wiring longer to go from solar panels to charge controller and possibly some #2 (though for the #2 I don't think I'll need any soldering, just use lugs as it's just to go from inverter to battery)Going to just use a heat gun, or at least that's my plan - never tried that before, I still need to buy the wiring tomorrow. Was not able to solder it with a normal soldering iron, was just not enough wattage. The thinner solder was just turning into balls as well, but probably due to not being able to get the wire itself hot enough. Failing heat gun I'll try torch. Then electrical tape (insulation will probably melt slightly too I imagine) then shrink wrap.Open to other ideas though, just need to fuse thick wires together in a non mechanical way that will possibly be outside, so soldering seems like best plan. Low voltage.

author: Halcyon
author_rank: Unknown
timestamp: October 03, 2018, 03:03:21 am
content: Quote from: Mr. Scram on October 02, 2018, 11:49:19 pmThere are special soaps such asD-Leadspecifically for cleaning your hands after being in contact with lead. It's commonly used in armouries and shooting ranges. Regular cream soaps along with thorough scrubbing work just as well.

author: duak
author_rank: Super Contributor
timestamp: October 03, 2018, 03:48:03 am
content: I was curious about high lead solder and found this:"90/10 is used in some electronics for its higher melting temperature than eutectic solder. Using 90/10 inside a component will allow the component to then be soldered into its next higher assembly (such as onto a PWB) without the worry of solder joints inside the component reflowing and creating a defect. Sometimes the reflowing of solder inside a component may be a worry, other times it is not."I thought it might have been used in stained glass framing, but apparently not.

author: georges80
author_rank: Frequent Contributor
timestamp: October 03, 2018, 04:13:33 am
content: Why solder the wires? As mentioned, get decent lugs and use a crimper to make the connections. Slip some heatshrink with the meltable liner over the lug /wire connection point and you're good to go.Crimping cables for battery lugs etc is MUCH more preferable than a solder connection, I see no reason why you aren't doing the same with this somewhat thinner gauge.cheers,george.

author: BrianHG
author_rank: Super Contributor
timestamp: October 03, 2018, 04:39:21 am
content: I second the use of LUGS!!! as mentioned twice above. If you don't want to crimp, get the hex wrench screw type shown below. For my inverter setup, I have a bunch of the single ones in 2 sizes, for 1 gauge and 2 gauge wiring. I bolt the 2 sizes of wiring into the different lugs, then, bolt the lugs together. This makes it easy to remove, or add new wire connections/segments in parallel or serial in the future. 0 solder, 0 heat.

author: helius
author_rank: Super Contributor
timestamp: October 03, 2018, 05:01:08 am
content: Quote from: duak on October 03, 2018, 03:48:03 amThere are ranges of specialized alloys used for die attach bumps in flip-chip assemblies and on ceramic hybrids. They are often attached to gold pads, and contain a few percent of gold to help make a stronger bond. Common to them is a higher liquidus so that the dies cannot detach during PCB reflow.

author: forrestc
author_rank: Unknown
timestamp: October 03, 2018, 05:15:16 am
content: Quote from: Red Squirrel on October 03, 2018, 01:43:31 amDon't solder. You really do want a mechanical splice (as others have said).A split bolt is one option. Another is a splice as shown belowthere are also crimp connectors.You can waterproof it either with appropriate marine heat shrink or self-fusing electrical tape. The self-fusing tape needs some explanation - it's basically tape which when wrapped around a joint it fuses with itself to provide a waterproof layer. There are multiple options out there. And multiple ways to use it (some like to wrap the joint with normal tape, then fusion tape, then cover with more electrical tape - others just use it by itself).Of particular note on soldering: Solder really should only be used in those cases where you can join the wires so they are electrically stable without the solder, then solder applied. In the US, the electrical code says: "Soldered splices shall first be spliced or joined so as to be mechanically and electrically secure without solder and then be soldered.". The purpose of the solder is to make the already electrically and mechanically spliced wire more stable over the long term (so the twisted together wires don't work themselves loose). The best way to think about this is to think about what happens to your joint when the solder gets hot and drips off. The joint should be stable enough so that the solder isn't really needed.Because of the hassle of doing all of this, mechanical splices have been developed to the point where soldering isn't required. And for most mechanical splices isn't recommended.

author: gildasd
author_rank: Frequent Contributor
timestamp: October 03, 2018, 05:37:52 am
content: I have opened a few cabinets to check.Everything in that size range has as primary holding/conducting a crimping of some kind. Everything is mechanically held.A few connections are crimped, then soldered (with normal solder), but I imagine that is for other reasons.I will ask the sparkies why next shift.

author: forrestc
author_rank: Unknown
timestamp: October 03, 2018, 08:34:32 am
content: Quote from: gildasd on October 03, 2018, 05:37:52 amMy guess is that they'll say that a crimped/mechanical splice is almost as reliable as a good quality soldered joint, and much more reliable than a poor solder joint. And the soldered joint takes far more time. So it is cheaper/easier/more time efficient, and there is little real benefit to soldering.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 03, 2018, 05:35:01 pm
content: Quote from: georges80 on October 03, 2018, 04:13:33 amIt's too extend a cable and not to connect to a terminal. The cables I bought ended up being too short so I just need to add more length.Some of the lugs shown here do look interesting but again this is for an inline splice, that may possibly even be outside, and I have no idea where I'd even buy those connectors. I find anything "industrial/commercial" tends to be very hard to find. Can find the odd thing on Ebay/Amazon sometimes but even that is hit and miss. Most sites I find are also US and not Canada based so don't want to get hit with duties.That said if this high lead solder is a problem I'll try to order something else. I did not notice when I ordered that it was so high. This is the solder:https://www.amazon.ca/gp/product/B003X3VUDM/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1Suppose another option is to just buy PV connectors and crimper and use those to extend the wire.

author: Vtile
author_rank: Super Contributor
timestamp: October 03, 2018, 05:43:27 pm
content: I wouldn't be partially concerned if you do it with a good ventilation, of course the lead is toxic, but it is not cyanide and you are not working with it daily basis.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 03, 2018, 05:56:19 pm
content: Quote from: forrestc on October 03, 2018, 08:34:32 amA good mechanical splice should be more reliable than a solder joint. Proper splices are as strong as the wire or cable material.

author: metrologist
author_rank: Super Contributor
timestamp: October 03, 2018, 06:54:35 pm
content: Ha, this is funny because I recently acquired some 12L14 leaded steel and some concern over the lead content (0.35%) was expressed. I heard it should be welded, though. I thought that would be due to fouling, but I'm getting the impression the concern is due to lead vapors.

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 03, 2018, 07:01:26 pm
content: Quote from: Red Squirrel on October 02, 2018, 11:37:47 pmI been snorting this stuff everyday since I was a kid! Still here on the block at 60+ so I don't think you need to worry lols Of course some say the mind has gone..........

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 03, 2018, 07:19:31 pm
content: Quote from: metrologist on October 03, 2018, 06:54:35 pmWelding something is another kettle of fish. That definitely means vaporising some lead. Lead vapours are bad.

author: metrologist
author_rank: Super Contributor
timestamp: October 03, 2018, 07:31:21 pm
content: Quote from: Mr. Scram on October 03, 2018, 07:19:31 pmI did mean to say should not be welded. Is the health risk significantly enhanced though? Welding seems unhealthy anyway, and I also read that many steel and alloys have some lead, and possibly other bad stuff. Bronze or was it brass has several percent lead, for example.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 03, 2018, 07:45:13 pm
content: Yes-- the usual hazard in steel welding is due to manganese, leading to a Parkinsons-like condition (manganism).I wouldn't weld 12L14 and such without good ventilation (if welding them is even recommended in the first place, unsure?).Galvanized steel, and many bronzes (and brass, obviously), carry the risk of metal fume fever, from zinc which boils at a fairly low temperature. You wouldn't normally weld a zinc-bearing alloy of course, but they are commonly used for brazing filler, something to be wary of there.OP: have you checked with the local neighborhood electrical supply warehouse? They aren't necessarily wholesale, you should be able to find one that you can phone in the order, purchase via credit card and pick up at the front desk. You may be able to rent a crimp tool as well, otherwise use a screw lug part. Ask for a catalog or check inventory online if they have a website.The best solution -- the way I was taught -- if you cut the wrong length of wire,throw it outand cut it oversize, then down to size once routed. A painful lesson at 2AWG, but that 2AWG is carrying a lot of amps that you don't want to mess around with, either, eh?Tim

author: Bud
author_rank: Super Contributor
timestamp: October 03, 2018, 08:26:23 pm
content: Ham radio and audiophile shops should have a variety of nice beefy splices and boots. You can even get a gold plated ones

author: rdl
author_rank: Super Contributor
timestamp: October 03, 2018, 09:02:23 pm
content: Also, check at places that sell car stereo equipment. Those people that put high powered systems in their cars tend to use fat wires.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 03, 2018, 09:29:17 pm
content: Went to the electrical place to buy the wire I needed and asked what they had for splicing these wires together, they just recommended to solder, go figure haha.So I guess I'll just make sure I have good ventilation when I do the soldering and to use gloves to play things safe. Though I guess overall it's not a huge concern given I don't do this every day.

author: Nusa
author_rank: Super Contributor
timestamp: October 03, 2018, 09:55:27 pm
content: ~90% lead solder was often used on tube sockets back in the day because of it's high melting point. Some tubes ran so hot that they would melt the more usual 60/40.

author: coppercone2
author_rank: Super Contributor
timestamp: October 04, 2018, 01:38:00 am
content: is there any table that shows resistance of crimped connection to screw terminal vs soldered connection for various crimp types for the same wire gauge?

author: forrestc
author_rank: Unknown
timestamp: October 04, 2018, 10:04:56 am
content: Quote from: Red Squirrel on October 03, 2018, 05:35:01 pmhttps://www.homedepot.ca/en/home/p.6sol-8sol-split-bolt---package-of-2.1000409925.htmlhttps://www.homedepot.ca/en/home/p.copper-split-bolt-connectors-2-awg-maximum-2clam.1000843580.htmlhttps://www.homedepot.ca/en/home/p.liquid-electrical-tape-waterproof-seal-all-indooroutdoor-uses-includes-brush-black-4oz-1jar.1000751619.htmlhttps://www.homedepot.ca/en/home/p.scotch-130c-linerless-rubber-splicing-tape.1000101995.htmlhttps://www.homedepot.ca/en/home/p.scotch-33-electrical-tape.1000179489.htmlAlso, go to your auto parts store or somewhere which sells car stereos and amplifiers, often they'll have barrell connectors for large cable due to cables this big being used to wire up car stereo amplifiers.

author: BrianHG
author_rank: Super Contributor
timestamp: October 04, 2018, 11:48:07 am
content: Lugs? In Canada, I got them at an household electrical wiring store, 99cents CDN each.Lug CatalogThey are actually called 'Universal Terminal Cable Lug'. They are available but too expensive at Amazon.Also try here for Canada:Lug and connector store

author: BrianHG
author_rank: Super Contributor
timestamp: October 04, 2018, 11:53:54 am
content: LOL, check this out, Mouser full 1awg = $2.55 each, less in quantityhttps://www.mouser.com/ProductDetail/Panduit/LAMA1-0-14-QY?qs=tJLS%2F%2F8J1eWNpkUBQEmJLg%3D%3DAmazon = 57$ for 2, only the smaller 2awg :https://www.amazon.ca/Cl-Burndy-Universal-Terminal-KA26URK/dp/B000SBIRMO/ref=sr_1_fkmr0_4?ie=UTF8&qid=1538653981&sr=8-4-fkmr0&keywords=universal+terminal+lug+1+awgGo figure...Here are most of them at mouser:https://www.mouser.com/Panduit/Connectors/Terminals/_/N-5g5u?P=1z0z80lZ1z0zl4eZ1z0yy6b

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 05, 2018, 12:36:58 am
content: Those types of lugs are more for end point connectivity and I got that covered (will use lugs with crimper), though it's good to know I can buy them, they are similar to what is used in telcos to connect to big copper bus bars. I will need stuff like that in a future project as I want to redo my DC power setup at home and move the batteries away from the server room as they have different ventilation requirements and easier to keep separate so I can meet those requirements. Right now nothing is ventilated as it's not enclosed as a room yet.

author: BrianHG
author_rank: Super Contributor
timestamp: October 05, 2018, 06:32:01 am
content: Quote from: Red Squirrel on October 05, 2018, 12:36:58 amNote, to merge 2 cables, I would use a lug on each wire, and place a huge heat-shrink on the cable, get a large nut and bolt and bolt them together, and heat shrink away. You can also place 3 on to of each other, 2 on one side, 1 facing the other with a longer bolt for a 'Y' connection of 2 2 awg wires from 2 battery banks to 1 hug wire on the other side... I also had cables with crimped lugs, however, at the time, without a good tool to crimp 4,2,&1 awg, I liked these guys and where I bought them, they were under 1$ each, at a local utility electrical supply shop which had fuse boxes, wiring, and tons of this heavy-duty stuff in stock.

author: cs.dk
author_rank: Unknown
timestamp: October 05, 2018, 04:43:40 pm
content: At my job, we are extending cables with this type of crimped butt-splices;https://eu.mouser.com/Connectors/Terminals/_/N-5g5u?P=1yzu4ynZ1z0z4xuZ1yzxc0h

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 25, 2018, 11:39:22 pm
content: Finally got around to trying this. Decided to try this after work since I don't get much time off lately, but days are too short now so was rushing to get done before it's too dark. Yeah this solder is a fail, it requires way too much heat as mentioned, so all the flux just melts before the solder even starts to get softer. So could not get it to really solder properly.I don't like the idea of a mechanical splice to extend a wire when it will be outside as you would normally want a special watertight junction box for that but that does seem to be the easiest route as mentioned so think I'll just bite the bullet and do that.Found these at home depot:https://www.homedepot.ca/en/home/p.butt-splice-kit-2-8-awg-1cd.1000150077.htmlWill save me from having to order more stuff and wait more if I go that route.From the get go I should have just bought all the equipment needed to make my own MC4 cables at this point would have ended up being cheaper.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 26, 2018, 09:47:21 am
content: If touching lead was an issue, air gun enthusiasts would have shown that ages ago.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 28, 2018, 12:13:51 am
content: I guess is it only really a danger if it is ingested? I guess kinda like mercury? (except for organic mercury that stuff is pretty crazy)

author: coppercone2
author_rank: Super Contributor
timestamp: October 28, 2018, 07:34:37 am
content: guns tend to make a small lead spray when they fire because the primer is a lead based salt that pretty much detonates and the bullet also rips through the barrel and abrades along its length so you get some fine lead (and barrel) dust + burned/vaporized oils that are also probably catalytically acted on by the dust/flame mixture under high pressure in the barrel. I would not be surprised if you get some organic lead compounds that form in very slight quantities under those conditions.. probably varies on barrel pressure and powder type too. You need to keep in mind something like a shotgun barrel gets 12000 PSI. One of those fast low drop rounds like a .17 fireball has something like 60,000 PSI in the barrel, along with flame temperature and high contact pressure/friction. Strange reactions can occur in this regime. Keep in mind the barrel is made of metals which are commonly known to act as catalysts (transition metals).Not the healthiest activity. Even more so with guns that automatically cycle ammunition, but even a bolt action might leak a bit under those pressures.I would rather work with carefully ventilated lead smelting then gunfire from a exposure stand point.https://www.minnpost.com/earth-journal/2017/05/recreational-shooters-are-carrying-lot-lead-their-blood-analysis-shows/

author: GreyWoolfe
author_rank: Unknown
timestamp: October 28, 2018, 12:34:45 pm
content: Quote from: Red Squirrel on October 25, 2018, 11:39:22 pmDon't forget the self amalgamating tape and covering it with Scotch 33 electrical tape for UV protection, also available at Home Depot-- solid waterproof connection. That is how I waterproof connectors on my ham radio antennas.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 28, 2018, 06:40:05 pm
content: Quote from: GreyWoolfe on October 28, 2018, 12:34:45 pmOh right guess if this splice is meant for underground the shrink wrap might not be UV protected. Though I think I will look at getting some conduit and split it down the middle and then wrap it around where the wires go into the shed. Will also protect them from rubbing against the shingles. For now I just used a plastic bag lol. Temp fix.

author: stj
author_rank: Super Contributor
timestamp: October 29, 2018, 04:21:21 pm
content: lead is soft, you cant join heavy cables with it unless your securing them somehow - potting shell for example.otherwise they can eventually pull apart.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 30, 2018, 12:18:00 am
content: That might be the issue then. Would I have had better luck with regular 60/40 solder? Just need to find some thick one and make sure I actually get 60/40 this time. Might have to give it another try later on so that I'm more prepared next time I need to join thick wires together. Another thing I was thinking after is I could have pre-thinned the individual strands, then join them together, and then use the heat gun. Maybe that would have worked too.

author: forrestc
author_rank: Unknown
timestamp: October 30, 2018, 07:17:39 am
content: Quote from: Red Squirrel on October 30, 2018, 12:18:00 amPlease, for fire safety/etc go back and read several of of the original posts telling you that soldering these is NOT the correct approach.You should NEVER use solder to join wires which are not already electrically and mechanically joined in a stable fashion. Using solder to mechanically and/or electrically join wires is asking for a fire and failure. There's a reason why Mechanical splices (like the one you found) are the safe/preferred alternative anymore. There are simply too many traps to soldering current-carrying wire which can result in fire due to the solder joint degrading over time.I'm thinking you might be working under the assumption that a soldered connection is better in some way. It might be for low voltage/current stuff, but for higher current/voltage work it tends to be the wrong approach.

author: stj
author_rank: Super Contributor
timestamp: October 30, 2018, 11:14:13 am
content: the only way i have seen heavy cables soldered - battery leads.is after both ends have been inserted into a copper tube and crimped.the solder was really just to prevent corosion / oxidisation inside the crimp.and lead-free solder is the strongest - less lead = more tin and tin is stronger.but that's not important if it's crimped.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 30, 2018, 06:46:12 pm
content: Quote from: forrestc on October 30, 2018, 07:17:39 amEverything I've read seems to say soldering is always the best connection if you are looking to splice two ends together permanently, is that not the case? I recall reading something to the effect that it was the only NASA approved way, there is a specific way to braid it together first though which I sorta did.Ended up using mechanical splice anyway but can't imagine doing tons of wires that way as it would get pretty pricy. These were about $12 a pop. Most of the methods mentioned here would also not work for an inline splice as it would be too bulky for shrink wrap.

author: helius
author_rank: Super Contributor
timestamp: October 30, 2018, 07:59:11 pm
content: A Western Union splice is the only way to join wires with solder. It provides a strong mechanical and electrical connection before the solder is introduced.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 30, 2018, 08:04:17 pm
content: Soldering is useless without strain relief.Are you referring to the Union Splice? That works because the wire itself is reasonably stiff, and the wires being wound around each other, the joint is, well, the thickness of two wires twisted together -- which is to say, stiffer than a single wire alone, and so there will be little flex within the joint, and little tendency for the soldered joint to peel apart.PCBs only work because THT leads are constrained by the board material (the solder doesn't need to provide much strength, and it's usually lining a hole), or because SMT pads don't have much strain on them, mostly just the mass of the component itself. When either of these assumptions is broken (e.g., a single-layer board, with loose-fitting holes and a lot of flex, being prone to cold solder joints or torn pads; SMT connectors, or large inductors, being notorious for fatiguing or tearing off), failures soon follow.Note that SMT is just lap joints; it works because the strain is low. THT is mostly about shear and compression.I'm not really sure how you'd solder a huge power cable. The solder won't even wick into the strands. You could tin each end with a solder pot, but then you still have to wrap the cables around each other somehow (lots of love with some big pliers??), and you still can't fill the joint with solder (shoving solder into the joint will just see it drain out, leaving voids). You could wrap it with a mold and fill it, I guess? Or, you could Union Splice each individual strand -- that would be fantastic, as I'm sure you can well imagine, but it would be a truly stupendous amount of work, too!So, I'm not really sure how you'd arrange the joint in the first place. A lap joint is straight out just too weak, but there's not really anywhere to go up from there, short of a truly heroic effort...Speaking from experience here -- I recently did a small filter choke, in 8AWG stranded, for a prototype project. It's "dead bug" mounted on flat (copper clad PCB) stock, with SMT "gull wing" joints (i.e., round bar on flat plane lap joint). I had trouble tinning these "pins" already, and if I fully melted the joint where it is now, most of the solder holding it down I think would just run out over the board...If we're talking #2 size welding cable (fine stranded), it'll probably soak up solder nicely, and being more flexible, should have less strain on the joint, too. But still nowhere near good enough that a lap joint would suffice. And with such flexibility, making a Union Splice would still be tricky.So, overall much better to go with a cold compression joint, like a crimp or screw terminal. Screw terminals seem particularly awful, but industry likes them, so they can't be too bad.Tim

author: forrestc
author_rank: Unknown
timestamp: October 30, 2018, 08:13:54 pm
content: Quote from: Red Squirrel on October 30, 2018, 06:46:12 pmSoldering is a good *addition* to an already good mechanical splice. If you've spliced two wires together so they would be safe electrically (ignoring insulation here for a second) without the solder then you've got a joint where the addition of solder will be helpful. A good youtube search term is 'lineman splice' or 'western union splice' or more recently 'nasa splice'. I happened to find the video at. Note at about 4:50 in this video he actually tests the splice without any solder. You could actually tape this up without solder and it would be serviceable for a reasonable period. The addition of solder just helps make the joint that much better and tends to protect the joint from oxidation.Without doing the mechanical splice first, the connection is subject to failures due to various solder failures. Often the joint will have a higher resistance than the wire, causing that point to heat up and the solder to become enough of a liquid to flow off of the joint. If the cable is under mechanical stress, most solder isn't very strong, and so that point will fail first, etc. That's why at least in the US the electrical code says you must first form a mechanically and electrically stable connection before applying solder.For larger cables, this method isn't practical so almost 100% of the splices are with some sort of compression or crimp fitting. A crimp connector is probably the best, assuming you have the right tools. Unfortunately for larger cables these are expensive since the larger tools are typically hydraulic in nature. The screw type fittings like you have are a good second best option, and superior to a typical lap soldered joint.It should be noted that under no circumstances should the cable be tinned or the ends soldered before using one of the screw or other compression fittings since the solder tends to deform over time and will cause it's own set of problems.