Terminating Litz Wire?

[GonzoEngineer]

Do any of you gentlemen have any good tips for terminating Litz Wire?

Specifically, I am using 2 ga. Litz Wire.(420 strands x 28 ga.) (.450 inch diameter)

Dipping the ends in a solder pot is a pain in the ass! There has to be a better way!

 

[Nigel Goodwin]

Do any of you gentlemen have any good tips for terminating Litz Wire?

Specifically, I am using 2 ga. Litz Wire.(420 strands x 28 ga.) (.450 inch diameter)

Dipping the ends in a solder pot is a pain in the ass! There has to be a better way!

Dipping the end in a solder pot sounds like the easiest way you could find? - dip it in liquid flux first though as well.

 

[Sceadwian]

Why not use a coax or bnc crimp tool and thick walled aluminum or copper tube of the appropriate diameter as a binder? I would trust dipping in a solder pot for a really sure termination but crimping is widely used because it's fast cheap and simple, and if done well is as reliable as solder. Being Litz wire solder will work exceptionally well as it will naturally wick into the wires, though as Nigel says dipping in liquid flux (especially a thin one) will give you superior results. That being said a good solid crimp connection is just as reliable and a whole lot faster than waiting for a solder pot to heat.

 

[Leftyretro]

Why not use a coax or bnc crimp tool and thick walled aluminum or copper tube of the appropriate diameter as a binder? I would trust dipping in a solder pot for a really sure termination but crimping is widely used because it's fast cheap and simple, and if done well is as reliable as solder. Being Litz wire solder will work exceptionally well as it will naturally wick into the wires, though as Nigel says dipping in liquid flux (especially a thin one) will give you superior results. That being said a good solid crimp connection is just as reliable and a whole lot faster than waiting for a solder pot to heat.

Would crimping really work? I thought the advantage of Litz wire was that each individual wire is insulated from the rest allowing the maxiumum 'surface area' exposed for best performance for RF frequencies (skin effect per area).

Anyway solder pot is probably the only effective way to terminate such a large diameter litz wire bundle.

Lefty

 

[Roff]

Would crimping really work? I thought the advantage of Litz wire was that each individual wire is insulated from the rest allowing the maxiumum 'surface area' exposed for best performance for RF frequencies (skin effect per area).

Anyway solder pot is probably the only effective way to terminate such a large diameter litz wire bundle.

Lefty

You are correct. crimping alone won't work. It might help hold the bundle tight while you dip it in the solder pot.

 

[GonzoEngineer]

The problem lies in tinning the ends, it takes a lot of heat in a solder pot to burn off the insulation on each strand. The wire swells up, and solder wicks up inside making an ugly mess.

A crimp connection after tinning does not work, because the solder is too soft for a reliable connection as it eventually loosens up.

I am making inductors that handle 600V/600A pulses, so litz wire is about the only way to go.

What I am trying to find is a solvent that will dissolve the insulation, but haven't had any luck.

 

[MrAl]

Hi,

Did you try paint remover? That and something to remove that after application, like paint thinner.

Possibly, separate into groups of smaller diameter.

 

[GonzoEngineer]

Hi,

Did you try paint remover? That and something to remove that after application, like paint thinner.

Possibly, separate into groups of smaller diameter.

Off the shelf paint removers and solvents do not affect cross linked polymers.

There used to be small bottles of solvent sold in Radio/TV parts stores many years ago, (CG brand if I remember right)....but it has been removed from the shelves because of toxicity and liability.

 

[Roff]

Gonzo, did you check out this patent? The text seemed (to me) to imply that only a portion of the individual strands were to be inserted into the sleeve. I had to look at the drawings to realize that he was actually bundling all the wire into the sleeve.

 

[GonzoEngineer]

Gonzo, did you check out this patent? The text seemed (to me) to imply that only a portion of the individual strands were to be inserted into the sleeve. I had to look at the drawings to realize that he was actually bundling all the wire into the sleeve.

Good find, THANKS ROFF!......I owe you a beer!

I found the patent, and now have an idea of how to perfect it.

(Idaho huh? a great State!)

 

[Roff]

You have to create an account to view images. Here is the line in the page I linked to:

View Patent Images: Images are available in PDF form when logged in. To view PDFs, Login or Create Account (Free!)

 

[GonzoEngineer]

You have to create an account to view images. Here is the line in the page I linked to:

Thanks again Ron.....I found the complete patent on another site. I am headed in the right direction now.

 

[saturn1bguy]

Off the shelf paint removers and solvents do not affect cross linked polymers.

*NO* solvent will affect a cross-linked polymer. But I highly doubt your insulation is a cross-linked polymer (like nylon, PEX, teflon, etc). It's likely a varnish of some type that sport's some solvent in its makeup. That's the solvent you seek, the same one in the varnish or lacquer.

Start with methanol, then move to propanol, acetone, MEK (2-Butanone), and end with Xylenes. If those don't do it, you're mostly out of luck...

 

[Sceadwian]

How about a blow torch? Burn off the insulation, and use a weak acid to clean off the oxidation? Just don't keep the heat short enough not to vaporize the wire.

 

[GonzoEngineer]

*NO* solvent will affect a cross-linked polymer. But I highly doubt your insulation is a cross-linked polymer (like nylon, PEX, teflon, etc). It's likely a varnish of some type that sport's some solvent in its makeup. That's the solvent you seek, the same one in the varnish or lacquer.

Start with methanol, then move to propanol, acetone, MEK (2-Butanone), and end with Xylenes. If those don't do it, you're mostly out of luck...

Been there...done that.....but thanks for the advice.

 

[Leftyretro]

You would think that the manufactures of Litz wire would understand that their wire if going to have to be terminated to be useful and would publish information on how best to remove their insulation and terminate the wire Having to reference patents seems to be pretty severe step/solution.

Lefty

 

[eblc1388]

Go to the following website for info and watch the video at the bottom of the webpage on the actual process demonstration of insulation stripping.

**broken link removed**

 

[jpanhalt]

It took awhile to find the MSDS, the chemical is just a molten salt bath of NaOH, NaNO3, and NaCl.

Trade Name: Dip Strip
Chemical Name – Caustic Soda
Formula – Sodium hydroxide, sodium nitrate, sodium chloride

I suspect the sodium nitrate helps for nylon, judging by the short times for removal of that insulation.

In my personal experience with NaOH/NaNO3 salt baths (used for another purpose), I was a bit leery at first, but got used to it. Nevertheless, it seems one would need to do a lot of stripping to justify the set-up.

John

Edit: I don't have any Litz wire to test (mine is all solderable), but one might consider coating the end in brazing flux, heating to melt the flux, hold for several seconds, cool and wash. The molten brazing flux is basically a molten borate salt, which is quite alkaline and helps maintain a constant temperature to avoid over-heating the copper.

 

[henry webber]

Lets see if a Limey from across the water can help. I have a bit of experience with large Litz cable, and have been in touch with New England Wire who manufacture the cable. They will sell you a chemical in paste or liquid form to remove the laquor. One type is Chlorine based, the other a Caustic base. Both work well to remove the laquor, however there are COSHH (Containment Of Substances Hazardous to Health) issues, but they do work successfully. It has also been confirmed by the manufacturer that you can crimp these cables. Personnally I would use a small blow lamp to locally heat the cable to turn the laquor into carbon ash, then use a small wire brush to clean that away. It is then possible to crimp the cable. Yes the point of Litz cable is to get over the Skin effect by all the cores being individually insulated, but at some point they have to come together. I'd like to see someone connect (in my case 10,000) strands individually. Hope this helps.

 

[kubeek]

Well, your post comes about nine years too late, but thanks for the info anyway