Melting cooper wire with a soldering iron.

Solder dissolves copper.

There is copper-bearing "savbit" solder that does this much less.

"John Larkin"

As the name suggests, it was intended to save wear on plain cooper bits as used in most soldering irons back then.

Then iron plated bits became the norm.

Even with Savbit, soldering copper wires of 0.05mm or less needs skill and speed.

This pdf shows the effect of the added copper in Savbit.

Around 1000 times improvement compared to using pure tin solder.

... Phil

Try turning down the iron temp (if it's controlled).

I've tinned #37 many times (~4.5 mil dia.) and have dissolved it before. Guessing the stuff you're working with is even thinner.

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

"Tim Williams"

So she has to burn the lacquer coating off first, so a tip temp of circa

IIRC, its about 1.5 thou of an inch dia.

Electric guitar PUs use similar wire.

.... Phil

Sylvia Else brought next idea :

Not answering your question BUT How does low resistance reduce the battery consuption?

"John G"

Hint - it minimises I squared R losses....

.... Phil

It happens that Phil Allison formulated :

Yes it reduces the I sqared R losses but would only increase the BATTERY consumption by applying a larger voltage to the load. Very small changes in this case I admit.

"John G" Phil Allison

A motor ( etc) using copper wire has LESS battery drain since it is MORE efficient.

Think it all the way through.

... Phil

As others said, the solder is dissolving the copper. If you can get Savbit, that would help, or you could saturate a small blob of solder with copper yourself, and then use it with some fresh flux on your wire. Solder that is saturated with copper can seem a bit "gritty" and is normally not very nice to use.

When making coils with fine wire, sometimes I fold over some of the same wire repeatedly, to form a bunch (maybe 4, 8 or 16 strands) and then twist it together with the thin wire that I am soldering, to give the lead-out wire from a coil some more mechanical strength. It also gives the solder a larger number of wires to attack, which might help to reduce the rate at which any individual strand in the bunch is disappearing. Getting the soldering done quickly will obviously help.

Chris

Try using Savbit.. Or, in this case,try suckkie SAC; in either case the copper in the solder prevents wire size reduction due to alloying copper from the wire.

This is the one rare case that SAC is useful; in Immersion Silver PCBs, it is a disaster.

Thanks for the replies, everyone. I suppose I should have realised that the wire was being dissolved, since I was vaguely aware that solder eats away soldering bits. I remain surprised that the effect could be so fast.

Sylvia.

What I do Or have done in a past life winding electrical stuff with fine wire, is to twist the two bits tight together for about 1/2" then get very fine flame and touch the end (just momentarily)and it will usually melt into a blob thus joining it.

We used to use a chemical to first remove enamel coating, called XVar [from memory]

Simply dip the wire into the chemical, hold for a while, swirl around, remove, and instantly solder.

Paint stripper will work for most wire coatings.

Jeroen Belleman

Then there's this

If there' any alloying going on, it's not soldering, it' brazing. Soldering is strictly a surface covalent bonding process.

Hello, the first time it happened to me whas when I tried to solder enamelled wire extracted from an old car ignition coil, it was very thin and it "melted" if the soldering process was a bit slow. I always tought it was due to Cu-Sn alloy.

temperature reduces slightly Cu content of the alloy (Sn-Cu

down the dissolution speed, lead seem to be on it's own since doesnt like to alloy to Cu at these low temperatures.

Ciao!

I was going to mention Xvar.

Never managed to find any. The only place I saw it was at a place that made moving coil meters.

Wish I could find some. I don't like "self-fluxing" wire, it needs too high a temperature.

GC electronics used to sell Strip-X. I don't know if it's still available.