Melting cooper wire with a soldering iron.

Actually, of course, it's totally impossible.

So I wonder what's really happening.

I've been modifying a quartz clock, and needed to solder the very thin enameled copper wire that its motor uses. Repeatedly, I was finding that the wire broke while being soldered, for all the world as if I was melting through it.

I can't see how it can be anything other than copper wire in this application. It's the right colour, and low resistance is important to reduce battery consumption in the clock as originally sold.

Any thoughts?

Sylvia.

Reply to
Sylvia Else
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Solder dissolves copper.

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

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
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Reply to
John Larkin

"John Larkin"

** The only kind I ever use is Multicore "Savbit" - around since the 1960s.

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.

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Around 1000 times improvement compared to using pure tin solder.

... Phil

Reply to
Phil Allison

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

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Seven Transistor Labs 
Electrical Engineering Consultation 
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Reply to
Tim Williams

"Tim Williams"

** Problem is, the OP is trying to tin *enamelled* copper wire.

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

350C is needed.

** The thinnest I have worked with was the wire used in the original Sennheiser HD414 headphones - rated at 2000 ohms per ear piece.

IIRC, its about 1.5 thou of an inch dia.

Electric guitar PUs use similar wire.

.... Phil

Reply to
Phil Allison

Sylvia Else brought next idea :

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

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John G
Reply to
John G

"John G"

** Works for loudspeakers, transformers and every other use of copper wire in electronics.

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

.... Phil

Reply to
Phil Allison

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.

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John G
Reply to
John G

"John G" Phil Allison

** No.

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

Think it all the way through.

... Phil

Reply to
Phil Allison

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

Reply to
Chris Jones

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.

Reply to
Robert Baer

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.

Reply to
Sylvia Else

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.

Reply to
F Murtz

Sometimes the FLUX can do that ... it's designed to "clean" the copper, and it does that by chemically attacking the copper oxide layer on the surface. On VERY thin wire the chemical action may be enough to dissolve not only the oxide but the underlying metal too.

Try a different brand of solder ... maybe try something like silver solder.

Reply to
Mr. B1ack

"Mr. B1ack"

** Pretty wild piece of speculation - seeing as ordinary solder flux is sometimes used to coat and protect the copper layer on PCBs.
** Nuts.

.... Phil

>
Reply to
Phil Allison

Einstein said it: "it is all relative"; fine wire making it stand out).

Reply to
Robert Baer

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http://aws.org/wj/supplement/WJ_1975_10_s370.pdf 

JF
Reply to
John Fields

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