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How to strip and tin litz wire

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LAN_403

2Spoons

Fri Dec 07 2012, 02:25AM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

If your litz has the nice melty enamel that strips with an iron you can stop reading now. However if your litz has been made with high temp enamelled wire - the stuff that doesn't melt at soldering temps - here's a little trick for getting the enamel off 50 strands of 40AWG!

It seems that the polyimide insulation can be degraded by caustic soda. After a couple of tests just soaking in caustic soda solution for an hour or two I found that all you need to do is this:

Mix about 1 teaspoon of caustic soda (aka lye, sodium hydroxide) with 1 teaspoon of water - this make a very strong solution. Use a glass, ceramic or plastic container.
Hot concentrated caustic soda is nasty stuff: wear gloves and eye protection. Dispose of leftover solution by flushing down the drain with lots of water

Dip the end of the litz wire into the solution, bringing it out wet. Heat the wet end with a tinned soldering iron - it will sizzle and spit so keep face and hands away. Once dry dip again to get a another drop on the wire. Heat again - the wire will sizzle, go dry, then sizzle again as the polyimide reacts with the caustic soda. At this point you will find the enamel can be wiped off with the hot iron, leaving tinned wire behind (assuming you had a little solder on there).

I can't believe its this simple, but I've now done it several times to my home made litz and it works every time.

Patrick

Fri Dec 07 2012, 04:15AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

ive had the very same problem , and will try this method.

But where did you get the lye? is it drain hair ball cleaner?

Dr. Slack

Fri Dec 07 2012, 08:15AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Patrick wrote ...

ive had the very same problem , and will try this method.

But where did you get the lye? is it drain hair ball cleaner?

It's drain *grease* cleaner - turns the grease into soap, probably be white crystals, but may be an aqueous solution, then it's lye.

If it's specifically for hair (and paper ) then it's more likely to be concentrated sulphuric, which oxidises organics, and will only be a thick liquid.

Both are strongly exothermic on solution, so the warnings may not distinguish them.

Pinky's Brain

Fri Dec 07 2012, 04:10PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

I wonder if you could add an ultrasonic transducer to a cheap solder pot.

teravolt

Fri Dec 07 2012, 05:09PM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

I use a solder pot at work. maby you could find a used one on ebay. it takes about 30 secs

...

Fri Dec 07 2012, 06:12PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

This method is specifically for the 'high temperature' litz wire, for which a solder pot does not work.

So far the only method I have heard of for getting the insulation off is by using hot NaOH

Patrick

Fri Dec 07 2012, 08:26PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

... wrote ...

This method is specifically for the 'high temperature' litz wire, for which a solder pot does not work.

So far the only method I have heard of for getting the insulation off is by using hot NaOH

i use a razor blade or a dremel with sanding drum, but its a pain.... and inconsistent.

teravolt

Sat Dec 08 2012, 02:33AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

depends on how hot your solder pot is the one at my work gets 1000F. If the wire is 26 awg or larger sand paper woks or a blade

Hazmatt_(The Underdog)

Sun Dec 09 2012, 12:38AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

If the wire is small enough, like 40 strands of 38 awg or so, what i do is just get a decent size ball of solder hanging off the tip of my iron and pass the wire in. The varnish will succomb sooner or later.

2Spoons

Sun Dec 09 2012, 02:34AM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

The two problems with the thermal methods are: 1) it doesn't work with high temp magnet wire, and 2) 40AWG copper wire dissolves quite quickly in solder so you have to be quick with the soldering iron (or solder pot).
Similarly sanding or scraping 40AWG is very difficult to do without breakage.

The lye I used is sold as drain cleaner. We can't get the sulphuric acid drain cleaner OTC in New Zealand, only the lye type.

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