Making connection to very fine wire?

My experience with trying to connect enamel-coated wire (much thicker gauge than yours) to a 'chocolate block' terminal was that the screw cut through the copper before it punctured the enamel. I doubt if you could expect much success with a crimp terminal. Modern self-fluxing varnish usually breaks down if you can get it, and the wire end, up to soldering temperature.

In the past I have connected fine wires made of 'unsolderable' material using a 'Mitcham tagstrip', (so called because Philips and Mullard radios used them). Wind about 6 turns of thin tinned copper wire around the shank of a small drill bit, then thread the unsolderable wire through it and fill it with solder. This usually results in a connection, especially if you scrape the wire a bit while it is surrounded by molten solder.

If that is a bit too big for your purposes, you could try something similar by lacing the wire through a solder blob on a small piece of perforated Veroboard.

Good Luck.

Some sort of chemical etch to remove the enamel would be ideal but I don't know of any. Maybe some experienced ppl that have done this and that hang out here can be of help. What has worked for me is to use some extremely fine sandpaper, e.g. >500 grit and gently drag it across the strands. It is a delicate balance of using enough force to mechanically remove the enamel and not stress/break the strands. I've also use a exacto/modeling knife to scrape away the enamel but not nicking the wire to the point of breaking it is tricky. A magnifying glass comes in hands for this kind of work.

You can then use flux to help remove remaining impurities & enamel when soldering. Wrapping the strands around a thicker piece of copper conductor, tie in place with a piece of copper wire to secure it may be helpful. There is also a technique where thin solder is wrapped around the joint, heat the wires and at some point the solder will melt.

I don't know of any crimp that would work in this situation as they use mechanical force to make a connection. With this fine a wire, I don't think it would hold up. Good luck J

Depending on the varnish there are several ways to get it off not counting the scrapeing . Some will burn the varnish off with the heat of the soldering iron. On others I have taken a butane lighter and burnt off the insulation then clean off the burnt part.

Most varnish will break down at soldering temperature. To get up to temp work against a firm insulating surface ( newspaper) (rather than working in mid-air) so you get good pressure and heat transfer. Tin the wires the same way. having extra flux to brush on may help.

That saves me some time & frustration of trying it myself, thanks.

Great idea. Even if the strands are solderable, this could be a good way to manage such small strands.

Maybe as the last resort :-)

I have a bottle of methylene chloride (the stuff good paint strippers used to be made with) - it would be worth a try.

"it is tricky" indeed - I have had the frustration of trying. I might come to being desperate enough to do it again.

...

That would be a good way to keep all those tiny strands in place

I agree

Thanks for the help

I'll try the soldering iron. I suspect that any flame might destroy the copper along with the varnish - it is really thin. Either way, the burnt residue would have to be dealt with. RA flux might do it.

Thanks

Heat is beginning to sound like the best approach, thanks.

Thanks "guys". I'll followup with my results.

With earphone cables it has been my experience that you can simply solder the wires without stripping them. The coating seems to vanish under the solder flux.

Methylene chloride is what we used as a stripper when we soldered ends on Monster rca cables.

We have a winner.

Trying the simplest first, I used a soldering iron to burn off the varnish. And threw on some solder to conduct the heat better. To my great surprise, the solder stuck. Worried that maybe it looked good, but was just sticking, without making good contact, I checked the resistance. 0.7R with a so-so DMM. That's over 4 feet of conductor. Good enough for me.

Decades ago I recall a varnish that was specificaally formulated to become a flux when soldering. So I am sure it is possible, but whether that is what you have got is a different matter!

It's very common nowadays, so the chances are that these wires will be insulated with it.

Back in the stone age, when telephone coil cord wiring was made of "tinsel" (copper foil), we had a similar problem. I would strip off any insulation from the tinsel wires with either furniture stripper, desoldering braid or Xacto knife. However, instead of soldering directly to the tinsel, I would find the smallest diameter uninsulated wire strand and wrap the tinsel with the fine wire. To give it more strength, I would continue wrapping around any remaining insulation. After wrapping, apply solder. From the photo, you might need to remove some of the solder you added.

There is a further hazard which nobody has mentioned yet: if the wires are very fine (48swg or higher) and they are made of copper, they will dissolve in ordinary solder. The way to overcome this is to use a solder that is already saturated with copper, such as "Savbit".

It rarely causes a problem with normal work, but becomes significant in the repair of moving coil meters and similar fine work.

I probably do have it, given the ease with which I was able to get solder to stick. What a great idea - I hope the company that invented it made a lot of money from it.

I remember that stuff. I specifically remember trying to solder it and failing. When I saw the tinsel in this ear bud cord I immediately thought of that phone cord & anticipated a lot of grief. Your solution sounds like even if it hadn't wetted the tinsel, it would have made a mechanical connection. Whatever works.

From the photo, you might need to

Actually I had to re-do, so there might not be as much. But it's done, so removing some is not in the cards. Why, though, should I have done it?

Thanks

I didn't measure the strands, but 8 of them twisted together made a

0.01" diameter conductor. Pretty fine. Time will tell, but with any luck I'll be dead before it's a problem.

Thanks