Removing enamel from coated wire

[13hm13]

Certain earphones use enamel-coated STRANDED wire cables. (For Sennheiser and other high-end brands, these cables may also have very fine Kevlar fibers).
The loomed wire strands are VERY fine-pitched.
In repairing (splicing) these cables, it's necessary to remove the enamel insulation from the wire. Googling for ideas, the usual "solutions" pop up (lighter flame, sandpaper) and even some unconventional suggestions (heating powder aspirin, with wire dunked in -- haven't tried this yet!).

Because the wire strands are so fine-pitched, flame or sandpaper will often destroy the strand. So I'm looking for an alternative solution. Not sure how much heat is needed to melt enamel w/o harming the metal.
Or maybe some chemical . Tried Acetone -- it did nothing.

Below is sort of what I'm up against (not my image)...

[iMo]

The aspirin (containing acetylsalicylic acid) works for finest enameled stranded wires (I used to use for high Q coils). Mind the fumes and odour are pretty unpleasant.
Another approach I did was I put the stranded wire into a flame and the copper wires melted into a small copper ball easy to solder.

[Benta]

Flame is too harsh. Enamel coated strands normally have a solderable enamel. Use a soldering iron and eutectic solder.

[Siwastaja]

Enamel coated strands normally have a solderable enamel. Use a soldering iron and eutectic solder.

(Emphasis added.)

I have heard this many times before, but it is quite a stretch, IMHO. In my experience, a solderable enamel is quite a special product. I have never seen it in wild in products, except when I have specifically bought it myself. Even then, it's much harder to source than normal, non-solderable enamel.

This being said, it doesn't hurt trying, possibly using higher-than-normal soldering temperature, and adding a lot of extra flux to compensate for burning flux at that high temperature. Just don't be surprised if it does not work.

[Benta]

n my experience, a solderable enamel is quite a special product. I have never seen it in wild in products, except when I have specifically bought it myself. Even then, it's much harder to source than normal, non-solderable enamel.

Interesting. I have the opposite experience with thin, stranded cables, they're mostly solderable.
On components like toroidal power transformers or inductors that have thick enamel wire I agree with you, they need to be scraped free.

[Illusionist]

If it's not solderable enamel (I have never found any of that mythical stuff either) I would be tempted to try dipping in a liquid paint stripper, like this: https://www.amazon.co.uk/MODELLERS-STRIPPER-REMOVER-ENAMEL-ACRYLIC/dp/B008VGUBWC

Any proper paint stripper should at least soften the enamel to the point that it can be carefully wiped off with a tissue.

[13hm13]

Haven't tired paint remover. I was hoping acetone (nail polish remover) would remove the wire "enamel" guessing nail polish enamel and wire enamel were similar. As I noted, acetone did not work.
The hackaday article suggests that regular flux and solder will remove enamel. This could be a real "DUH!!" moment. The answer was in front of me all the time! Would make sense though for mass-production.

https://hackaday.com/2016/11/22/iron-tips-soldering-headphones-and-enamel-wire/

[Electro Detective]

Haven't tired paint remover. I was hoping acetone (nail polish remover) would remove the wire "enamel" guessing nail polish enamel and wire enamel were similar. As I noted, acetone did not work.

The hackaday article suggests that regular flux and solder will remove enamel.

This could be a real "DUH!!" moment. The answer was in front of me all the time! Would make sense though for mass-production.

https://hackaday.com/2016/11/22/iron-tips-soldering-headphones-and-enamel-wire/

Sounds too easy and I think I've been there before with not much luck, or a poor job of it, so..


A while back I used one of those Radio Shack/Realistic badged fibre pen?    thingies last time I ran into those unsolderable annoying  headphone wires,

after trashing an inch or two with failed attempts, till I figured out with help from the multimeter that the iron and solder wasn't faulty 

With repetition the adjustable fibre pen sort of gently 'sweeps off' the coating just enough for solder to grab   


FWIW and YMMV > water soluble plumbers flux or some strong acid may be worth a try,
use just enough with a Q-tip or stiff metal brush to expose the metal strands and wash the stuff off quick,
then prep and solder the usual way   

Have not tried that (yet  ) but it may be worth a shot for someone who runs into these dramas often enough,
and has the flux or acid on hand

Don't forget the gloves and eye/face protection 

[StuartA]

The last time I looked in to this was about 10 years ago. I found one product on the market which used a combination of some metal salts (I think it was a mixture of sodium nitrate and sodium hydroxide) which became molten at something like 250'C and they claimed that it removed the enamel. Interesting as it was, we did not actually buy one to try and just got by with scraping.

S

[CatalinaWOW]

Neither of my solutions are "good" answers, but they have worked for me when I have had to solder these types of wires.

1.  Scraping the wire with a hot soldering iron.  The heat softens the coating enough that you can get it off (eventually) even if the coating is not designed to be solderable.  There is no warranty that all of the coating will be gone, but enough to make contact.  As mentioned in earlier posts a delicate hand is required because it is easy to damage the wire.

2.  "Sandpaper".  I put this in quotes because the grit size has to be appropriate for the wire size and in the smaller sizes that means something other than conventional sandpaper.  This does a better job, but requires patience and care. 

Magnification is very useful for both approaches, particularly for those of use with older eyes.

I am really glad I rarely have to solder these smaller wires because daily dealing with them would have forced me into some other hobby entirely.

[Zero999]

I've found most enamel wire is solderable, but it requires a higher temperature than normal. I find 400ºC and plenty of flux works quite well.

[KL27x]

Solder pot. Dip the end in the pot AND stir it around. After the enamel melts, it still wants a good reason to go somewhere else, else it just sticks around. When you stir the wire through molten solder, you leave a trail of enamel that floats to the surface and burns up into black schmoo. You do this as quick as possible so the wire gets cleaned and tinned before it dissolves into nothing.

[KL27x]

Sounds too easy and I think I've been there before with not much luck, or a poor job of it, so..

+1. This is complete gawbidge. Well, I mean sure. Encourage people that it can be done. But it can be done a lot better, and if you're gonna write a frikking essay on it, you could include some better information.

 

[Electro Detective]

ok, I'll bite 

I tried the method in that URL years ago before the author was conceived and it was a fail,

the old school MIG Sennheiser headphones wire is tough and stubborn

Careful abrasion techniques or whatever chemicals break down that coating, and clean up and prep and low temp leaded solder is the only to go afaik 

Sorry for the short essay 

 

[eliocor]

I set my iron tip (Weller) to 415°C and (using fresh solder) i "touch" the enamelled wire. It works every time.
Please take care: it generates a nasty smell!

[Buriedcode]

I've repaired quite a few headphone cables and they almost never have "solderable" enamel on them.  You can buy solderable enamel magnet wire, but I haven't seen it used in headphones.

I used to burn the enamel off then clean with fine grit sandpaper.. but now I just use ~200 grit sandpaper.  Two or three passes and its done - the rest does seem to come off during soldering.  Thankfully its such a thin layer it doesn't take much, but as the wire is also so thin, go easy.

[David Hess]

I have a big spool of roughly 28 gauge solderable enameled wire so it does exist.  It is very red looking compared to typical and 700F burns the enamel off in seconds.  I use it for point to point wiring when I need something better than wire wrap wire and there is no need for color coding.

[KL27x]

^I bought a spool of solderable enamel wire, 28 gauge. It, too, is very red.

Despite the packaging says it is solderable at 300 degrees, I can't tell the diff between it and any other small gauge transformer wire I've ever used. Yeah, it is solderable with an iron, but it's neither clean nor easy. Hotter temps, longer dwell times, and propensity for cold joints.

[langwadt]

^I bought a spool of solderable enamel wire, 28 gauge. It, too, is very red.

Despite the packaging says it is solderable at 300 degrees, I can't tell the diff between it and any other small gauge transformer wire I've ever used. Yeah, it is solderable with an iron, but it's neither clean nor easy. Hotter temps, longer dwell times, and propensity for cold joints.

I've never had problems with it, sticking a fresh cut end into a blob of solder on the iron works a treat

[Psi]

If anyone wants to source thin enameled wire where the iron burns off the coating look for wire that goes into a wiring pencil for PCB repair.

https://www.newark.com/roadrunner/rrp-a-105/wire-wiring-pencil-38awg-pk4-38m/dp/20J5555
http://www.farnell.com/datasheets/2575104.pdf

[KL27x]

^Product information states: Requires a temperature of 400℃ + to remove enamel
??

Been done tried too many of these to have any sort of optimism. Esp at the price and product description.

I've never had problems with it, sticking a fresh cut end into a blob of solder on the iron works a treat

Might just be difference in preferred soldering temps.  I have reasons to not like going too high. Screws up a lot of other mojo to me. You don't have to strip it; you just have to clean your iron off before every joint. Not worth the tradeoff of just stripping kynar, to me, but I got really good at stripping kynar. This topic seems to reveal a huge divide in personal preference for reasons which might be less than obvious.

For instance:

sticking a fresh cut end into a blob of solder on the iron works a treat

1. This is stripping. Not much different from just stripping a wire. It's not like you just take the wire and solder it to the joint. (Unless your joint is a big/hot enough blob to strip it as you solder?)
2. The cut end? Deal breaker. You have to cut the second side of the wire and turn your pcb around and pick this wire end with tweezers to solder it. I hardly ever solder a kynar wire like that. I strip a big chunk off the end, solder that, then break the insulation on the other end in the middle of the wire and slide it down. Then solder the second end. Without ever letting go of the wire or having to turn the pcb this way or that.

When your second end is cut, you have to turn around the pcb. You have to reacquire the wire with tweezers. You have to get it to the joint, and the wire will twist in your tweezers and always point up away from the joint in the wrong direction (well, at least 19 times out of 20). So you bend it the way you need it and bring it back to the joint, and the wire punks you. As you get it closer, it twists and turns the other way. If you strip a kynar wire in the middle, you just bend it to go where you want and it stays there. It doesn't slip or twist in your tweezers cuz you don't use tweezers at any point. The extra wire is wrapped around your finger.

[langwadt]

^Product information states: Requires a temperature of 400℃ + to remove enamel
??

Been done tried too many of these to have any sort of optimism. Esp at the price and product description.

I've never had problems with it, sticking a fresh cut end into a blob of solder on the iron works a treat

Might just be difference in preferred soldering temps.  I have reasons to not like going too high. Screws up a lot of other mojo to me. You don't have to strip it; you just have to clean your iron off before every joint. Not worth the tradeoff of just stripping kynar, to me, but I got really good at stripping kynar. This topic seems to reveal a huge divide in personal preference for reasons which might be less than obvious.

For instance:

sticking a fresh cut end into a blob of solder on the iron works a treat

1. This is stripping. Not much different from just stripping a wire. It's not like you just take the wire and solder it to the joint. (Unless your joint is a big/hot enough blob to strip it as you solder?)
2. The cut end? Deal breaker. You have to cut the second side of the wire and turn your pcb around and pick this wire end with tweezers to solder it. I hardly ever solder a kynar wire like that. I strip a big chunk off the end, solder that, then break the insulation on the other end in the middle of the wire and slide it down. Then solder the second end. Without ever letting go of the wire or having to turn the pcb this way or that.

When your second end is cut, you have to turn around the pcb. You have to reacquire the wire with tweezers. You have to get it to the joint, and the wire will twist in your tweezers and always point up away from the joint in the wrong direction (well, at least 19 times out of 20). If you strip a kynar wire in the middle, you just bend it to go where you want and it stays there. The extra wire is wrapped around your fingers and doesn't twist and stick and point wherever it wants.

I hardly ever solder wires like that on a board unless it is a bodge wire and SMD

[KL27x]

Me either. I can put in bodge wires to traces and SMD pins with the kynar like this almost all the time. I bend form the middle section of exposed wire over the point of a micro chisel (other end of the stripper) to get it where it can be connected (to say line up over a short section of scraped trace) and it actually remains lined up when I solder, make joint, shear it off.  To a PCB pin/pad, bend the end into an L or more acute bend to get it to touch where you want and not short. Pie's the limit when the wire stays placed and oriented how you want it to while soldering it.

Jumpers short as a even having just a few mm insulation, no problem. Just have to leave plenty of exposed wire on the first end, to slide the insulation bead down. 

Takes just a tiny spell to figure out which end has to be soldered first to get it to go seamlessly. Rarely, rarely, ever have to cut the second end of the wire prior to soldering. I have a proper iron stand, so swapping between iron and stripping/cutting tool is very easy without looking.

The main reason to use enamel wire for PCB jumpers, in my book, would be if you ever need/like to completely hand wire high density SMD stuff. If they were to obtain the right tools and learn the simple techniques, I think most enamel wire folks would jump ship.

Most of the techs I have introduced and taught this method have been initially skeptical. Some are so smart or stubborn they immediately tell me why their way is better, and no, thank you. Every one that has actually tried it has been converted and thanked me, later, and their stripper/chisel is a cherished tool for PCB rework. If and when they have left the company, their stripper tool guaranteed goes with them.

[13hm13]

Hey folks, TS here ... cool responses.

I did try the hackaday suggestion (which many of you also suggested) and it worked.
Specifically, with cables on my Sennheiser IE-8 (in-ear monitor 'phones). I simply dunked the enamel wire in drop of rosin flux. Then used a std. pencil iron to heat up the enameled wire. The enamel came off almost immediately. And resoldering the wire was, hence, trivial. So, with that lighter, I've been a fool all these years!!

BTW: The real bitch of this cable is separating the Kevlar fibers from the wire stands.