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Electronics => Beginners => Topic started by: SnipTheCat on October 03, 2016, 09:13:12 pm

Title: Power cords with wires impossible to solder
Post by: SnipTheCat on October 03, 2016, 09:13:12 pm
I have been asking myself for a long time about this and didn't really find answer, and since I make my own power cords I am less faced with the problem than before.

The problem is that those power cords seems to have pretty dark wires (multibrain), When you try to solder you can some bubling and a lot of dirt as you cet with enamelled wires, but here the soldering doesn't stick to it. If you are patient enough you may have something that seems soldered, but usually you pull it apart quite easily. I have tried flux, no help, tried higher soldering temperature, no help...

Anyone knows any magic for those?
Title: Re: Power cords with wires impossible to solder
Post by: Mechatrommer on October 03, 2016, 09:21:07 pm
scrap off the blackish thing with knife..
Title: Re: Power cords with wires impossible to solder
Post by: Monkeh on October 03, 2016, 09:22:14 pm
Get some decent cables.
Title: Re: Power cords with wires impossible to solder
Post by: blueskull on October 03, 2016, 09:27:22 pm
Some really cheap cables use unrefined recycled copper. Since many recycled copper comes from scrap wall sockets or power strips, they have high phosphorous and beryllium content, which makes them hard to wet by solder.
Solution: buy high normal quality cables with either low recycled content or refined recycled content. You will not see crappy copper in Longwell or Volex cables.

Edit: s/high quality/normal quality/g
Title: Re: Power cords with wires impossible to solder
Post by: Monkeh on October 03, 2016, 09:28:02 pm
s/high quality/normal quality/
Title: Re: Power cords with wires impossible to solder
Post by: SL4P on October 03, 2016, 09:35:43 pm
To increase flexibility, some wires are spun around, or interleaved with fibre/glass threads,  these are notoriously hard to solder, and are designed to be welded or crimped - not soldered.
Title: Re: Power cords with wires impossible to solder
Post by: stj on October 03, 2016, 09:57:03 pm
maybe using crimp bootlace-ferrules would help.

if you do, get a 6-sided crimp tool - not a 4-sided one.
like this:
http://www.ebay.co.uk/itm/141578568204 (http://www.ebay.co.uk/itm/141578568204)
Title: Re: Power cords with wires impossible to solder
Post by: SnipTheCat on October 03, 2016, 10:17:20 pm
Thanks for all the quick replies :-) I would think of the oxidized/impure copper... I have also seen those cables interleaved with fiber, they are also a pain to solder. I guess I'll just get decent cables instead to try to reuse crap... What is sad is that these had preddy decent gauge (~1mm^2 per wire)

 About scrapping the dark parts or even trying vinegar+salt I had very very little success
Title: Re: Power cords with wires impossible to solder
Post by: tautech on October 03, 2016, 10:24:04 pm
Thanks for all the quick replies :-) I would think of the oxidized/impure copper... I have also seen those cables interleaved with fiber, they are also a pain to solder. I guess I'll just get decent cables instead to try to reuse crap... What is sad is that these had preddy decent gauge (~1mm^2 per wire)

 About scrapping the dark parts or even trying vinegar+salt I had very very little success
Sometimes a solder with a more aggressive flix can save the day, along with a much hotter iron.
A bit of a fiddle with some snippets can usually find a solution.  ;)

When all else fails scraping the conductors to shine them up can and does sometimes work or you'll have to resort to crimping ferrules or some other suitable terminal.
Title: Re: Power cords with wires impossible to solder
Post by: mikeselectricstuff on October 03, 2016, 10:25:46 pm
Probably copper coated aluminium (CCA) which is evil.
Chop it & replace with proper wire.
Title: Re: Power cords with wires impossible to solder
Post by: bitslice on October 03, 2016, 11:19:49 pm
if you do, get a 6-sided crimp tool - not a 4-sided one.
like this:
http://www.ebay.co.uk/itm/141578568204 (http://www.ebay.co.uk/itm/141578568204)

Thanks for that,
I was looking for a bootlace crimper but didn't realise they did hex versions in that size  :-+
Title: Re: Power cords with wires impossible to solder
Post by: Audioguru on October 03, 2016, 11:37:06 pm
Copper wires that have been wet for a long time have black copper that is hard to solder to.
Title: Re: Power cords with wires impossible to solder
Post by: SnipTheCat on October 04, 2016, 11:29:59 am
Probably copper coated aluminium (CCA) which is evil.
Chop it & replace with proper wire.

I have the feeling that's what it was... anyway, tossed it away and got proper cable ;-)
Title: Re: Power cords with wires impossible to solder
Post by: Lightages on October 04, 2016, 03:20:16 pm
I have also seen many cables with copper coated steel wire.
Title: Re: Power cords with wires impossible to solder
Post by: rob42 on October 04, 2016, 04:50:46 pm
try aspirin or other active flux
Title: Re: Power cords with wires impossible to solder
Post by: george.b on October 04, 2016, 05:16:36 pm
try aspirin or other active flux

Aspirin?  :wtf:
Title: Re: Power cords with wires impossible to solder
Post by: Len on October 04, 2016, 05:38:17 pm
try aspirin or other active flux

Aspirin?  :wtf:

If soldering is giving you a headache, take aspirin and use a good flux.  :)
Title: Re: Power cords with wires impossible to solder
Post by: Monkeh on October 04, 2016, 07:02:02 pm
try aspirin or other active flux

Aspirin?  :wtf:

Works really well. Say goodbye to your tip, too.
Title: Re: Power cords with wires impossible to solder
Post by: electr_peter on October 04, 2016, 08:01:54 pm
Probably copper coated aluminium (CCA) which is evil.
Chop it & replace with proper wire.
I have also seen many cables with copper coated steel wire.
Metal strands can be made out of steel - check with magnet. Or it can be CCA, as Mike mentioned.

Either way, I would toss this cable out and get proper cable with copper strands. Copper clad aluminium or steel is not good in mains power cables (it is a desperate cost saving measure from a manufacturer, which results in very high resistance cable).
Title: Re: Power cords with wires impossible to solder
Post by: stj on October 04, 2016, 09:14:25 pm
could make a good flexable heating element!  :-DD
Title: Re: Power cords with wires impossible to solder
Post by: george.b on October 05, 2016, 07:15:07 am
Works really well. Say goodbye to your tip, too.

No kidding? Gotta try that one, sometime. Who knows when such a trick might come in handy...
Title: Re: Power cords with wires impossible to solder
Post by: rob42 on October 05, 2016, 01:46:13 pm
Quote
Aspirin?  :wtf:
its just acetylsalicylic acid, you can use any other weak acid, like orthophosphor, acetic (vinegar), formic etc.
or weak organic (used in no-clean fluxes): palmitic, oleic, succinic, glutaric, paraffine / stearine, glycerine...
Title: Re: Power cords with wires impossible to solder
Post by: george.b on October 06, 2016, 02:53:11 am
Quote
Aspirin?  :wtf:
its just acetylsalicylic acid, you can use any other weak acid, like orthophosphor, acetic (vinegar), formic etc.
or weak organic (used in no-clean fluxes): palmitic, oleic, succinic, glutaric, paraffine / stearine, glycerine...

I know, but I thought it would decompose at soldering temperatures, didn't imagine it'd work!
Title: Re: Power cords with wires impossible to solder
Post by: helius on October 06, 2016, 03:09:10 am
It may decompose, but it is an ester, so if it hydrolyzes at the ester bond it will produce two other acids: salicylic and acetic. I think water soluble fluxes frequently contain similar esters.
Title: Re: Power cords with wires impossible to solder
Post by: george.b on October 06, 2016, 04:06:23 am
Aha, I see. Chemistry is not my strong suit ;D thanks!
Title: Re: Power cords with wires impossible to solder
Post by: johansen on October 06, 2016, 04:18:21 am
Some really cheap cables use unrefined recycled copper. Since many recycled copper comes from scrap wall sockets or power strips, they have high phosphorous and beryllium content, which makes them hard to wet by solder.
Solution: buy high normal quality cables with either low recycled content or refined recycled content. You will not see crappy copper in Longwell or Volex cables.

Edit: s/high quality/normal quality/g

If they add the phosphorous as some kind of deoxidiser or something, that might make sense.
But its hard to believe there would be enough beryllium in there to prevent it from soldering. unless they dumped a metric ton of relay contacts in with the 10 tons of copper. but i don't think that would be enough.. also if someone did have a metric ton of relay contacts, it would be recycled for the beryllium and silver, not dumped in a copper melt.

but if someone were to melt down 100 tons of power strips.. there would be enough brass in with the copper cord to raise the resistance to unreasonable levels.. however, still no beryllium

I have run across some 10 ohm, 6 foot long, iec power cords. not making that up. the servers they came with only pulled about 100 watts, so they would have survived, and their resistance was discovered after finding one of them was open circuit. the wires were not magnetic, had a color somewhere between brass and light brown..
Title: Re: Power cords with wires impossible to solder
Post by: rob42 on October 06, 2016, 04:56:01 am
I have used several times wires with inferior solderability, looked more yellowish, and not so flexible as a pure copper.
maybe, some brass-type alloy.
Title: Re: Power cords with wires impossible to solder
Post by: blueskull on October 06, 2016, 08:16:06 am
If they add the phosphorous as some kind of deoxidiser or something, that might make sense.
But its hard to believe there would be enough beryllium in there to prevent it from soldering. unless they dumped a metric ton of relay contacts in with the 10 tons of copper. but i don't think that would be enough.. also if someone did have a metric ton of relay contacts, it would be recycled for the beryllium and silver, not dumped in a copper melt.

but if someone were to melt down 100 tons of power strips.. there would be enough brass in with the copper cord to raise the resistance to unreasonable levels.. however, still no beryllium

I have run across some 10 ohm, 6 foot long, iec power cords. not making that up. the servers they came with only pulled about 100 watts, so they would have survived, and their resistance was discovered after finding one of them was open circuit. the wires were not magnetic, had a color somewhere between brass and light brown..

It is possible that there are something else other than Be and P, but brass should not be a huge problem in terms of solderability*. Actually, due to its slower natural oxidization, it can be easier to solder compared to copper when flux is not present.
But as I have said, it is very likely that they have just used unrefined recycled copper. While China makes some really high quality things such as latest iPhone or rockets even space stations, the capability of making high quality stuff is only privilege of selected large companies. For most small companies in China making electronics assemblies, they are just backyard studios with absolutely no process control and the only target is cheap. They do not care about quality or even safety, and they do not even bear their own company's name on their products. If it burnt down someone's house, there is no way to trace the source.

*: Though, reliability may suffer since brass introduces more elements, Zn and Pb, which do not exist in SAC solders. The introduced elements may for brittle IMC with other elements in the soldering interface.