Best Way to Clean Stranded Copper Wiring Before Soldering

[Ecomike]

Also Window cleaner will neutralize battery acid too. I used to know what was in it that did the trick, but I haven't had to maintain industrial batteries for several years now, and just can't remember.

Last time I checked window cleaner was either methanol or had Ammonia-D in it.

 

[1985xjlaredo]

I've always used hydrogen peroxide to clean up wire before I solder them. I don't think that I have done any harm ever. As for battery cabela if they are really messed up just replace them.

 

[CJR]

1985XJlaredo & Ecomike,

It appears that H2O2 (hydrogen peroxide) may be the first choice when trying to clean the copper wire because after cleaning it passivates (i.e. allows protective oxide layers to form on copper). If the H2O2 doesn't clean well enough, then perhaps using ammonium hydroxide followed with H2O2 may just be the ticket.

Excellent input!

Best regards,

CJR

 

[5-90]

1985XJlaredo & Ecomike,

It appears that H2O2 (hydrogen peroxide) may be the first choice when trying to clean the copper wire because after cleaning it passivates (i.e. allows protective oxide layers to form on copper). If the H2O2 doesn't clean well enough, then perhaps using ammonium hydroxide followed with H2O2 may just be the ticket.

Excellent input!

Best regards,

CJR

But doesn't an oxide layer inhibit conductivity?

 

[CJR]

5-90,

It is my understanding that the oxide coatings on copper and aluminum occur naturally to protect the base metal from corrosion. Cleaning copper with ammonium hydroxide, based on what I read, prevents the protective oxide layer from forming and then the copper rapidly corrodes where there is no oxide layers. I don't know to what degree the naturally occurring oxide layers affect the conductance in copper. But copper wires, with a naturally occurring oxide coating, are what we use for conducting current. So apparently, copper wire with normally occurring protective oxide coatings is acceptable and it appears to work well.

Best regards,

CJR

 

[kastein]

That is because they are on the outside. If they are on the outside and you try to solder or make a connection to the oxidized wire it will not make a good connection at all. As far as I know, silver and indium are the only metals with oxides that conduct reasonably well.

 

[5-90]

5-90,

It is my understanding that the oxide coatings on copper and aluminum occur naturally to protect the base metal from corrosion. Cleaning copper with ammonium hydroxide, based on what I read, prevents the protective oxide layer from forming and then the copper rapidly corrodes where there is no oxide layers. I don't know to what degree the naturally occurring oxide layers affect the conductance in copper. But copper wires, with a naturally occurring oxide coating, are what we use for conducting current. So apparently, copper wire with normally occurring protective oxide coatings is acceptable and it appears to work well.

Best regards,

CJR

I know that oxide coatings are often used to prevent corrosion (cf: anodising, "black iron oxide") but that's to prevent mechanical defect due to oxidation, I'd thought.

Besides, kastein's comment makes an interesting counter to yours.

I do know that oxide layers are naturally-occurring in metals, but are they always desirable? That's the question here...

 

[old_man]

That is because they are on the outside. If they are on the outside and you try to solder or make a connection to the oxidized wire it will not make a good connection at all. As far as I know, silver and indium are the only metals with oxides that conduct reasonably well.

I think the problem here is to distinguish between oxide and corrosion. Oxide is when the copper turns a brownish color. Corrosion is when you get the white crud.

Flux removes the brownish color allowing the solder to bond. It will do a little bit with the white stuff.

 

[CJR]

5-90,
"I do know that oxide layers are naturally-occurring in metals, but are they always desirable? That's the question here... "

From what I've read and understand, if copper is cleaned with ammonium hydroxide this cleaned area is prevented from forming protective oxide layers. So continued exposure of this unprotected area to corrosive chemicals, causes the copper grain boundaries to start to corrode, i.e. intergranular stress corrosion takes place. As the grain boundaries continue to disintegrate/weaken, the copper eventually cracks and breaks apart. So, in my view, the oxide layers would always be desirable because they prevent breakage at the grain boundaries.

Best regards,

CJR

 

[5-90]

5-90,
"I do know that oxide layers are naturally-occurring in metals, but are they always desirable? That's the question here... "

From what I've read and understand, if copper is cleaned with ammonium hydroxide this cleaned area is prevented from forming protective oxide layers. So continued exposure of this unprotected area to corrosive chemicals, causes the copper grain boundaries to start to corrode, i.e. intergranular stress corrosion takes place. As the grain boundaries continue to disintegrate/weaken, the copper eventually cracks and breaks apart. So, in my view, the oxide layers would always be desirable because they prevent breakage at the grain boundaries.

Best regards,

CJR

Hm. I guess that makes some sense - after all, CRES is still conductive even with the hard layer of chromic oxide on the surface (that's what makes it "Stainless.")

I do fairly well in elemental metallurgy and inorganic chemistry, but kinda come apart with electrochemistry...

 

[CJR]

Thanks for all the responses on cleaning STRANDED copper wire. I learned a lot. Unless someone else has something to add, the best cleaning approach that evolved here can be summarized as follows:

1. Clean wire with brake cleaner and/or soap/water to first remove grime.
2. Use OTC(over-the-counter) hydrogen peroxide (H2O2) with a Q-tip to clean copper of surface oxides.
3. Use the best, highly reactive rosin core solder (i.e. Kester 44 63Sn/37Pb 0.031", a eutectic with the lowest melting point and no clean-up of flux residue required) with some type of butane pencil/micro torch.

Alternate approach if ammonium hydroxide is used;
1. Clean wire with brake cleaner and/or soap/water to first remove grime.
2. Apply ammonium hydroxide with a Q-tip to clean copper of surface oxides. Copper now NOT able to naturally restore the protective oxide coating (passivation) required to prevent corrosion/disintegration/cracking of the copper grain boundaries.
3. Clean the copper with hydrogen peroxide (H2O2) so that copper can re-passivate itself again by forming the naturally occurring protective oxide coatings.
4. Use the best, highly reactive rosin core solder (i.e. Kester 44 63Sn/37Pb 0.031", a eutectic with the lowest melting point and no clean-up of flux residue required) with some type of butane pencil/micro torch.

Any comments/additions/corrections?

Best regards,

CJR

 

[kastein]

good point on the 63/37 alloy solder. Eutectic is MUCH easier to solder well with, since it freezes all at once instead of having a "mushy" state when the alloy is partially frozen. I didn't even really think about that, I bought ~8lbs of it at a swapmeet a few years ago and haven't bought solder since.

 

[1985xjlaredo]

This should be a sticky what with all of the posts we see about wiring and grounding problems. That and I never though a conversation about cleaning copper wire could be so technical.

 

[Ecomike]

1985XJlaredo & Ecomike,

It appears that H2O2 (hydrogen peroxide) may be the first choice when trying to clean the copper wire because after cleaning it passivates (i.e. allows protective oxide layers to form on copper). If the H2O2 doesn't clean well enough, then perhaps using ammonium hydroxide followed with H2O2 may just be the ticket.

Excellent input!

Best regards,

CJR

I agree with one exception. I think a degreasing (soap or solvent, Fantastic or 409, or ammonium hydroxide which is also a good degreaser if it has a surfactant in it, I think one of the major grocery store brands is a sudsing ammonia) step for most exposed underhood wires, and DI rinse would be best before using H2O2, as it is common for people to grease to exposed wires with dielectric grease and common for them to get slimmed by oil mists and leaks. If it is freshly skinned wire, with just a surface oxide layer then yes, I agree, go directly to H2O2 should work fine.

 

[Ecomike]

I think the problem here is to distinguish between oxide and corrosion. Oxide is when the copper turns a brownish color. Corrosion is when you get the white crud.

Flux removes the brownish color allowing the solder to bond. It will do a little bit with the white stuff.

Good points. There is also green copper corrosion, typically copper sulfate, from reacting with H2SO4, HSO3 vapors near the battery. Most of the white stuff and some of the green stuff is typically loose, powdery, and not a coating on the copper. The brownish stuff, as you said is typically an oxide coating, skin on the copper itself, a copper oxide CuO, that is chemically bonded to the surface of the wires. I think the white stuff is typically near the battery, and is lead sulfate?

 

[Ecomike]

5-90,

From what I've read and understand, if copper is cleaned with ammonium hydroxide this cleaned area is prevented from forming protective oxide layers. So continued exposure of this unprotected area to corrosive chemicals, causes the copper grain boundaries to start to corrode, i.e. intergranular stress corrosion takes place. As the grain boundaries continue to disintegrate/weaken, the copper eventually cracks and breaks apart. So, in my view, the oxide layers would always be desirable because they prevent breakage at the grain boundaries.

Best regards,

CJR

I think that is only true if the ammonium hydroxide is not washed away, and is only true for exposed copper. Rinsing the exposed copper with DI water and IPA, and drying the wire should allow a thin oxide skin to form quickly.

 

[Ecomike]

Thanks for all the responses on cleaning STRANDED copper wire. I learned a lot. Unless someone else has something to add, the best cleaning approach that evolved here can be summarized as follows:

1. Clean wire with brake cleaner and/or soap/water to first remove grime.
2. Use OTC(over-the-counter) hydrogen peroxide (H2O2) with a Q-tip to clean copper of surface oxides.
3. Use the best, highly reactive rosin core solder (i.e. Kester 44 63Sn/37Pb 0.031", a eutectic with the lowest melting point and no clean-up of flux residue required) with some type of butane pencil/micro torch.

Alternate approach if ammonium hydroxide is used;
1. Clean wire with brake cleaner and/or soap/water to first remove grime.
2. Apply ammonium hydroxide with a Q-tip to clean copper of surface oxides. Copper now NOT able to naturally restore the protective oxide coating (passivation) required to prevent corrosion/disintegration/cracking of the copper grain boundaries.
3. Clean the copper with hydrogen peroxide (H2O2) so that copper can re-passivate itself again by forming the naturally occurring protective oxide coatings.
4. Use the best, highly reactive rosin core solder (i.e. Kester 44 63Sn/37Pb 0.031", a eutectic with the lowest melting point and no clean-up of flux residue required) with some type of butane pencil/micro torch.

Any comments/additions/corrections?

Best regards,

CJR

Sounds like a great summary, for making this a sticky!!!!!

 

[CJR]

OK,

How do we make this a "sticky"?

Best regards,

CJR

 

[kastein]

Done and done!

 

[DaddyGreenGenes]

I've found that coca-cola works wonders. Then a little distilled water to wash the crud away.