Tips for soldering in-ear earphone wires?

[kalel]

In-ear earphones have a different type of insulation and wire than larger headphones (well, those I saw at least), or of course, speakers.

Replacing the cable entirely is "easier", but sometimes you can't even open the earphone.

I assume some people here must have done it successfully. I'd like to learn about any tips. Is it the same as working with "magnet wire"?

[fcb]

It's tricky, but it can be done. I run my iron at 400C for these, and use pool of solder on the tip.

I've lost count of the numbers of pairs of headphones/earbuds I've repaired with these types of wire for my kids.

[Ian.M]

I assume you are referring to the stuff with the individually varnish insulated and colour coded strands.   If so, then its *ESSENTIAL* to use copper containing solder - either Sn60/Pb38/Cu2 'Savbit' solder, or high copper SAC lead free solder, to avoid the solder dissolving the very thin strands resulting in weakening the strands where they emerge from the joint.      Its not the same as working with magnet wire as that's a single solid copper wire with varnish only on the outside, its more like working with Litz wire.

Stripping the varnish on the strands is a royal PITA - After separating them by colour, you can try fanning the strands and gently pinching them in folded fine grit wet&dry paper to get a start on it but they are so fine you are likely to have problems with breakage.  Try the old trick of resting the wire on an Aspirin tablet while tinning it with a hot iron, (old-fashioned dispersible real Aspirin, not a modern substitute) as the thermal decomposition products of the acetylsalicylic acid and the binders make a fairly good enamel stripper and a strong activator for the flux.  You could also try dipping the wire end for a short distance into a tiny drop of methylene chloride based paint stripper, waiting a few seconds then wiping with a tissue wetted with methylated spirits. Briefly burning off the insulation in a reducing (yellow) flame may also work, but it tends to oxidise the strands excessively which weakens them.   A combination of methods may succeed when one on its own fails.

[PA0PBZ]

Apart from the other tips I would like to add that it is probably a good idea to take them out of your ear first.

[GreyWoolfe]

Apart from the other tips I would like to add that it is probably a good idea to take them out of your ear first.

spoilsport.

[Ian.M]

Apart from the other tips I would like to add that it is probably a good idea to take them out of your ear first.

+1
Its a fiddly job so you really need to be able to see what you are doing.  You just need to get her indoors to lie down on your bench with the earbud in her ear to steady it . . .   

This forum needs a 'redneck' "just hold my beer and watch this . . . ." smiley!

[Alex Eisenhut]

The Aspirin works great to strip the varnish, I find that lowering the temperature of the iron helps, you want a brown bubbling mess, not a black bubbling mess.

You should also have some solder on the tip, I think the solder helps the thermal transfer on the wires. I've had more success with solder than without.

Either way, the smell is very pungent.

I repaired earphones, but I didn't inhale.

[tooki]

I assume you are referring to the stuff with the individually varnish insulated and colour coded strands.   If so, then its *ESSENTIAL* to use copper containing solder - either Sn60/Pb38/Cu2 'Savbit' solder, or high copper SAC lead free solder, to avoid the solder dissolving the very thin strands resulting in weakening the strands where they emerge from the joint.      Its not the same as working with magnet wire as that's a single solid copper wire with varnish only on the outside, its more like working with Litz wire.

What constitutes "high copper" lead-free solder?

[Zero999]

I assume you are referring to the stuff with the individually varnish insulated and colour coded strands.   If so, then its *ESSENTIAL* to use copper containing solder - either Sn60/Pb38/Cu2 'Savbit' solder, or high copper SAC lead free solder, to avoid the solder dissolving the very thin strands resulting in weakening the strands where they emerge from the joint.      Its not the same as working with magnet wire as that's a single solid copper wire with varnish only on the outside, its more like working with Litz wire.

Wow, I didn't know in-ear earphone cables are made like that nowadays. It's a long time since I've done anything like this. The really cheap ones I've looked at just use single core magnet wire, which is very unreliable. The better ones I saw, used one core with multistrand PCB PVC and another bare, only covered with the outer sheath.

Do you know why they use multi-strand Litz wire now? Is it to save space? What's wrong with one core insulated, the other bare, surrounded by an outer sheath?

[Ian.M]

@Tooki,
If you *MUST* use lead free, IMHO SAC357 Sn/Ag3.6/Cu0.7 would be the *minimum* to control copper dissolution.   Sn/Ag3.6/Cu1.0 would be better if you can find it, or try Kester K100LD, an Sn/Cu0.7/Ni-Bi alloy specially formulated to reduce copper dissolution.  However Sn/Pb/Cu 'Savbit' alloys are much easier to work with and are easier to buy in small quantities.

Also see https://www.eevblog.com/forum/projects/soldering-ultrafine-wire/ where the O.P was getting good results (no noticeable dissolution) soldering 54AWG copper wire with Edsyn Sn60/Pb/Cu2 FSW32 solder.

@Hero999,
I assume its the usual reason for stranded wire - to increase flexibility and improve fatigue life while retaining low resistance + a desire to minimise the diameter. 

[Alex Eisenhut]

I assume you are referring to the stuff with the individually varnish insulated and colour coded strands.   If so, then its *ESSENTIAL* to use copper containing solder - either Sn60/Pb38/Cu2 'Savbit' solder, or high copper SAC lead free solder, to avoid the solder dissolving the very thin strands resulting in weakening the strands where they emerge from the joint.      Its not the same as working with magnet wire as that's a single solid copper wire with varnish only on the outside, its more like working with Litz wire.

Wow, I didn't know in-ear earphone cables are made like that nowadays. It's a long time since I've done anything like this. The really cheap ones I've looked at just use single core magnet wire, which is very unreliable. The better ones I saw, used one core with multistrand PCB and another bare, only covered with the outer sheath.

Do you know why they use multi-strand Litz wire now? Is it to save space? What's wrong with one core insulated, the other bare, surrounded by an outer sheath?

That's nothing, the worst I've seen is tinsel wrapped around a core of very fine high-tensile strength mystery fibers.
It doesn't wet with solder, for all I know it's actually Christmas tinsel.

[SeanB]

Tinsel wire is easy to solder, just make an impromptu solder pot. A piece of scrap pine wood ( preferably with a knot that you can use) and drill a 10mm hole in it to 5mm depth, then simply make a pool of hot solder in it by feeding in solder and holding the soldering iron tip in it, then while still hot dip in the tinsel wire and it will tin. Pine knot works best, because the natural rosin in the knot acts as a very good flux, and keeps the solder ball clean and strips the wire coating off.

Just remember that you need strain relief in there as well, that solder join will be the weak point and will fail if it is flexed a lot, so ensure there is a firm grip on a non soldered bit of the cable to handle twisting motions and keep them away from the solder join.

[Ian.M]

Yes. I used to whip the end over the tinsel with a strand of fine tinned copper wire working back over itself towards the end to reinforce it then tin the very end.   Add some fine bore heatshrink and you'd have a reasonably reliable connection if nothing was yanking on it.

However instead of using a heat resistant Aramid core wound with copper foil tinsel, the crappy stuff uses Polypropylene or other cheap low melting point fibres for the core wound with aluminum foil tinsel.  Crimp or conductive epoxy are the only options.

[kalel]

Thanks for the ton of good tips. I'm not sure how many different kinds there are or the proper names for them, I will attach a few sample photos of some of the wires I have encountered: