Author Topic: Power cords with wires impossible to solder  (Read 5464 times)

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Offline johansen

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Re: Power cords with wires impossible to solder
« Reply #25 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..
« Last Edit: October 06, 2016, 04:21:48 am by johansen »
 

Offline rob42

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Re: Power cords with wires impossible to solder
« Reply #26 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.
 

Offline blueskull

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Re: Power cords with wires impossible to solder
« Reply #27 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.
 


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