Latest Chinese innovation - completely unsolderable wire

[TerraHertz]

For a PC upgrade I bought some SATA cables for slimline optical drives, which have a different SATA+power connector compared to hard disks.

They arrived from China, and the 5V power connector needs to be cut off and replaced with a 4-pin plug to fit the floppy drive power cable in the machine. I didn't want to hack anything in the PC, so this cable gets cut.
No problem, just solder the wires to the 0.1" header pins, right?

Except... the strands of wire in the red and black leads of these, ABSOLUTELY refuses to wet with solder. I even tried a flux pen, that can pretty much make anything solder well. Also makes for very sick lungs if you breathe the fumes, as I found out one time.

In the end I had to crimp lug real wire to it, so I could attach the improvised connector.
I captured a video using the little endoscope, of a strand of this stuff just shrugging off rosin-cored soldering attempts, and staying shiny clean. But it's 272MB, and I don't know how to edit+upload to youtube.

Pic 5 below is that wire strand, still clean after multiple times sitting in a blob of molten solder and flux on the iron tip.

Whatever this wire is, it's highly solder-phobic.
I'm starting to suspect it is actually finely stranded stainless steel. Would that _really_ be cheaper than copper, by enough to make it worthwhile to substitute?

Can anyone suggest a quick way to see if it really is stainless? It's non-magnetic, so far as I can tell.

[bktemp]

Could it be aluminium? I had a similar experience when trying to solder a connector to a cheap ethernet cable.

[Muttley Snickers]

Have you tried to scratch a core with a stanley blade to see if it is coated copper ?, I pulled a load of cables with spade connectors attached out of and old oven controller and they wouldn't tin either until scratched up.

[Brumby]

Have you tried to scratch a core with a stanley blade to see if it is coated copper ?, I pulled a load of cables with spade connectors attached out of and old oven controller and they wouldn't tin either until scratched up.

+1

[TerraHertz]

Could it be aluminium? I had a similar experience when trying to solder a connector to a cheap ethernet cable.

I don't think so, but could be wrong. Observations:
 * It's really shiny, in the way stainless can be. I've never seen aluminium look like that.
 * Tough. Folding a strand over a fingernail and pulling, or pulling with pliers till it breaks, it seems _much_ stronger than I'd believe a thin strand of aluminium could be.
 * It seems to work harden then fracture fairly quickly. As stainless does. But then so does aluminium...
 * It's hard to judge the melting temp, due to the thinness. But bringing a lighter flame gradually closer to it, it does seem to get up to dull red heat before collapsing/melting/oxidizing. After that it's very weak and brittle.

[Ian.M]

Stainless is *TOUGH* and has about 40 times the resistance of copper - I think you'd notice even just cutting it, and the voltage drop would be excessive for most electrical uses.

Sand a bit to get any surface coating off the strands, snip into very short lengths, and put it on a watch glass with a drop of strong caustic soda solution.  Warm gently.  If starts fizzing, its aluminium.

[TerraHertz]

Have you tried to scratch a core with a stanley blade to see if it is coated copper ?, I pulled a load of cables with spade connectors attached out of and old oven controller and they wouldn't tin either until scratched up.

Yes, first thing I tried. Sorry, should have mentioned that. Scraping repeatedly with a sharp blade results in no color change whatsoever. It's steely-looking all the way through.

[djQUAN]

Yeah that seems to be stainless steel. Or some sort of spring steel alloy. Aluminum really melts easily under lighter flame and does not discolor before melting when I tried some.

If it is really clean and shiny then turns brown in a flame, it could possibly be stainless.

[TerraHertz]

Stainless is *TOUGH* and has about 40 times the resistance of copper - I think you'd notice even just cutting it, and the voltage drop would be excessive for most electrical uses.

Yes, but both these are a bit hard to judge for very fine wire, that I only have a short piece of.
Cutting a strand - I don't know, it feels a bit tougher than copper or aluminium would. But the effort is tiny, so hard to judge.

Sand a bit to get any surface coating off the strands, snip into very short lengths, and put it on a watch glass with a drop of strong caustic soda solution.  Warm gently.  If starts fizzing, its aluminium.

Ah ha. Good idea. Only problem, I'm not sure I have any caustic... Hmm, what about degreaser?
Mmm, or maybe a bottle of hydrochloric acid. (It's outside, if the bottle is still intact.) Will look for it tomorrow, the place it's stored is spider domain at night.

[HAL-42b]

Is it magnetic?

You can also try a touch stone test.

Take a coffee mug and scratch samples to the unglazed bottom side. Scratch stainless aluminium and the unknown metal X. Compare the color of the scratches.

[chris_leyson]

Airbus A380 uses aluminium wire instead of copper, saves around 400kg to 500kg allegedly. Airbus had to put the plane on a diet 

[Jeroen3]

Soon...
http://www.stevenhale.co.uk/main/2012/05/sata-plug-melted/

[Ian.M]

Acids aren't so good for this.  You'll get *some* reaction with strong washing soda. 

Drain cleaner is also mostly caustic soda. If you can pick out a few white crystals with a pair of tweezers, dissolve them in a little water, and decant off the solution leaving any residue behind it should do.

CAUTION:  READ THE MSDS for SODIUM HYDROXIDE.  Appropriate PPE is *ESSENTIAL*.

[station240]

I think I've encountered this sort of wire before, I binned it without investigating as to why it's unsolderable.

Currentish scrap prices, steel 3 cents a kilo, copper $5.10, brass $3.65
So yeah the chinese are cheap enough to use steel given it's 170x cheaper.

The other thing they have apprently done is take mixed copper/brass scrap, and make it into copper wire.

[Theboel]

China made 75 Ohm coaxial cable with whatever type they like to stamp on the cable use inner use steel for a long time but they generous to plated with thin copper.

[wraper]

Unlikely to be a steel wire. Steel wire is very hard to cut, also it is very stiff and springy.

[SeanB]

Probably a steel wire made from recycled scrap which included a lot of chrome which dissolved in the melt, and then was drawn out to make a wire. Steel wire can be annealed, and if you had the right proportion of chrome it would be non magnetic, whilst not being a true stainless steel. Probably also had a copper coat, so was made into this wire as it is cheap.

If you had more I would try tinning it with a stainless steel flux, which is incredibly aggressive, and try a silver loaded solder, which will solder almost all clean stainless steels.

[retrolefty]

ATT/Western Electric made their rotary headset phone cable out of some metal/cloth fabric looking stuff that would not take solder at all. Crimp or die.

[helius]

If you had more I would try tinning it with a stainless steel flux, which is incredibly aggressive, and try a silver loaded solder, which will solder almost all clean stainless steels.

I think I read that orthophosphoric acid mixed with a few percent glycerol for viscosity is a good flux for stainless steel. Is that correct? And would ordinary SAC305 solder to it?

[SeanB]

ATT/Western Electric made their rotary headset phone cable out of some metal/cloth fabric looking stuff that would not take solder at all. Crimp or die.

I did solder those, though I also did use lacing twine to make sure the solder joint and the 5cm after it was held so it would not move even if held by the cord. Otherwise it would fracture in a few cycles.

[amyk]

In this application it's crimped, not soldered, so whether or not it's solderable doesn't matter to them.

[wblock]

Meh, cheap desoldering braid has been using unsolderable wire for years.  Just like those brown paper towels used in schools, it never gets used up because it never absorbs anything.  This reduces costs.

[tszaboo]

ATT/Western Electric made their rotary headset phone cable out of some metal/cloth fabric looking stuff that would not take solder at all. Crimp or die.

I had sennheiser cables, which refused to solder. They were very thin, individually coated something. Very frustrating to repair.

[Stray Electron]

  "Whatever this wire is, it's highly solder-phobic."


    That's not unusual.  It's designed to be flexible, not to be soldered to.  The curly telephone cords and telephone hand piece cords here in the US have been the same way since at least the 1960s.  Ask me how I know!  The stuff used in telephones looks like a  tiny piece of shiny Christmas tinsel!

[TerraHertz]

Here's some chemical ... well 'experiments' is too dignified a word for it.
Hunting around the house failed to turn up any drain cleaner, or any strong caustics better than vinegar.
But I do have a few old (very old) containers of acids, stored outside around the back of the workshop, under cover but on the ground. Where they won't wreck anything if the containers fail, and where the inevitable fumes leakage does no harm either. Apart from rusting the heck out of the metal case that's part of the cover.

The "sulfuric acid 30%" turned out to be about zero percent by now, leaving the hydrochloric and nitric.

I used some aluminum welding rod for comparison with the unknown wire. Sorry I have no idea of the strengths of the acids. The nitric was originally fuming, but now isn't. Still pretty wiffy, and reacts very vigorously with the aluminum rod.

First pic is my highly technical and precise outdoor temporary lab.

2562 Nitric - mystery wire: Took several seconds to show any action at all. Wire darkened, small amount of gas. Dissolved the entire strand of wire in a couple of minutes.
  Used fresh acid...
2563 Nitric - aluminium:   Immediate vigorous bubbling, dissolved right through the 1.5mm rod in less than a minute.

2564 HCl, mystery wire and Al rod at the same time: Aluminum reacting much more rapidly than the strand of mystery wire. The thin strand did eventually dissolve.

It's hard to judge the reaction rates by bubbling, since the thin strand has so little surface area. But it seems to dissolve much slower than the aluminum welding rod.

Not really conclusive, but I'm still leaning towards it being stainless steel of some kind. Maybe not a very good stainless alloy...