solder not sticking

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Rorie

Active Member
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I cut back some old cable and the wire is a copper colour. I cannot get the solder to stick.

I think you need a lot more heat for copper, so have the iron up to 450 degrees and have the heat on for a long time. I can get the solder to liquify, but it just runs off.

Any advice? I am not sure if the cable is copper or not, but i have never come across cable that i cannot get solder to stick too!
 
Our bench irons are 700deg F and we use cored solder for small wiring, external rosin flux for bigger stuff.

Sounds like you're not getting the heat into the wire, is the iron big enough?

Peter
 
... should have said, 450C. I am sure i am getting enough heat - i can solder 6mm cable with little effort. This stuff was about 1.5mm, so i am confident there is plenty of heat.

Every thread i find about solder not sticking says 'not enough heat', so thats the first thing i tried with no success :(
 
There's a lot of counterfeit cable about with an alloy or steel conductors copper coloured. There's a lot of concern in the electrical industry at the moment about it.

If your cable is copper then if clean it will tin easily.
 
Flux? haha, thats maybe a potential issue....none!

I just use normal, off the shelf solder. Would i need a specific kind for different kinds of wire?
 
Clean and degrease. Use seperate flux. If it still doesn't work, maybe it's not copper (seems unlikely though)
 
Ok thanks. If i just cut back the insulation on the cable, would it still need cleaned?
 
Rorie said:
Flux? haha, thats maybe a potential issue....none!

I just use normal, off the shelf solder. Would i need a specific kind for different kinds of wire?
Click to expand...
not necessarily, but modern RoHS compliant solder doesnt flow very well and doesnt attach to dirty components
 
Thanks for the replies. I'll try with some flux (is it a different flux from the kind plumbers use?). Whats the best way to clean the cables ready for soldering?
 
The wire might be copper, but there might be an enamel coating on it, that can be a sort of coppery brown colour too.
The enamel can be removed using abrasive paper, a knife to carefully scratch it away or I just use a clean flame from a cig lighter and clean up afterwards.
 
I've successfully used plumbing flux on wires, but you can get stuff that's specifically for electrical work. For soldering, it is usually quite acidic to eat through the oxides and any dirt on the surface. As Brian 47 says, I've come across wires that are coated with something which tends to repel solder. I assumed it was some sort of lacquer. In my case, I've found it burns off with a blowtorch flame. Preferably turned down fairly low so as not to incinerate the insulation.
 
Regarding a flux, it has two basic functions in soldering, first it "isolates" the job from the air while it's being heated therefore reducing oxidisation of the cleaned surfaces. The second function is to break down the surface tension of the molten solder so aiding easy flow.
The usual flux for electrical work is Rosin based, such as is found in the cores of "multicore" solder and also in the old tins of "Fluxite"; looks a bit like Marmite but I wouldn't advise getting them confused. Another (used to be) commonly used flux is "Bakers fluid", a liquid flux into which the job could be dipped before soldering. If all else fails, I have used candle wax in the past, tallow based candles are best, they were used by plumbers and telephone engineers years ago for working with lead pipes and cables.
The main problem with some fluxes, particularly in electrics and electronics is that they can leave an acidic residue which can damage the joint over time. There are proprietary flux removers which can be used after the joint has been made, usually applied with a small stiff brush. Meths can make a reasonable flux residue remover if nothing else is available.
With electronic circuit boards becoming ever more crowded and the techniques of surface mounting of components, there are some modern fluxes which don't require cleaning after the job.
 
Rorie said:
I cut back some old cable and the wire is a copper colour. I cannot get the solder to stick.

I think you need a lot more heat for copper, so have the iron up to 450 degrees and have the heat on for a long time. I can get the solder to liquify, but it just runs off.

Any advice? I am not sure if the cable is copper or not, but i have never come across cable that i cannot get solder to stick too!
Click to expand...
Not wanting to teach you to suck eggs. But I wonder if it's technique?

I thought I could solder, and I could to an extent. But I'd not been doing it correctly for years.

This vid should help explain the how's and the why's.

 
If your using 60/40 Sn/Pb multicore solder you should have no problems at 450degC, if you're using new "safe" solder then good luck, its complete dog shite.

Get the wire as hot as you can before applying any solder and it might take.
 
Roaming Wombat said:
If your using 60/40 Sn/Pb multicore solder you should have no problems at 450degC, if you're using new "safe" solder then good luck, its complete dog ****e.

Get the wire as hot as you can before applying any solder and it might take.
Click to expand...

Yes, I'd agree with that. The lead free stuff just isn't the same. I try and do it so the workpiece melts the solder rather than the soldering iron or gas flame. That tends to give me better adhesion.
 
Lead-free solder is like trying to solder with porridge. Stick to the proper 60/40 Lead/Tin stuff and it will be much easier.
 
Roaming Wombat said:
If your using 60/40 Sn/Pb multicore solder you should have no problems at 450degC, if you're using new "safe" solder then good luck, its complete dog ****e.

Get the wire as hot as you can before applying any solder and it might take.
Click to expand...

Thanks, I was wondering why I was sometimes having problems with solder having seemingly emulated teflon. I thought it was me not having cleaned it properly or the iron not hot enough. I've just realised I don't seem to have these issues when I pick up my ever dwindling reel of "old" solder. It's the new stuff. Why do they have to dick about with stuff that works and turn it into rubbish. I take it you can still get lead/tin stuff?
 
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