Soldering blackened/corroded copper.

[Dj Dunc]

Hi All

 

This is completely unrelated to Theatre and Events, and is in fact on an Automotive application, but I figured that if I put my other hat on and asked here, my question would be easily answered!

 

I'm dealing with a few cables 1 or 2mm² going into an unobtainable Sumitomo plug that have been corroded right the way up the loom (and at least to within the last 100mm of it). I need to reterminate these cables as I'm unable to replace or unpin the loom, and the components are like rocking horse poop.

Can people suggest a good method for cleaning off the oxidisation / corrosion of the copper so I can solder the joint? I don't have any flux, which I heard may do the trick, so if people reccomend a particular one, I'd be glad of a pointer.

 

thanks in advance

 

Duncan

[bigclive]

I usually try to cut back to clean copper if possible, but you may be able to scrape the surface tarnish off if it's a low current circuit. Flux might help, but my own experience with deep corrosion is that it results in weak solder joints.

[Robin D]

Using flux only stops clean copper from oxidising as you heat it. If the copper is not clean the solder will not bond properly to the copper. Using a small piece of fine Emery or wet n dry used dry until you see clean copper, then use a good contact cleaner (not WD40 as it contains a lubricant That will again stop the hot solder bonding.) Then use multicore solder which has the flux in the core of the solder.

 

You will also need to clean up the contacts in the connector. A needle file can be useful, or a cocktail stick wrapped with a tiny bit of wet n dry.

[Jivemaster]

Bakers fluid is the most aggressive soldering flux that's available, even when it's not on RS it's on ebay. Wash components well after use.

[bruce]

never actually tried it, but I’ve heard that mixing a solution of equal parts of white vinegar and salt, dipping the wire ends in for a few minutes, then neutralising by dipping in bicarbonate of soda solution, will do the job.

 

Or any other acid, I guess?

 

Internet Wisdom seems to be about 50/50 for and against this...

 

Vinegar (and brown sauce, and coca cola!) are excellent for cleaning old copper pennies!

 

 

If the wire in question is solid core, I’d be using emery paper or scraping, for stranded I might try the chemical solution.

[Glyn Edwards]

Is it really an unobtainable connector? This guy on ebay seems to have access to all manner of sumitomo stuff. He only lists the "popular" stuff but may be worth a try. Link What's the vehicle?

[musht]

 

Vinegar (and brown sauce, and coca cola!) are excellent for cleaning old copper pennies!

 

 

Vinegar and brown sauce be acetic acid, coke it`s phosphoric acid aka rust converter and etch primer on aluminium.

[Dj Dunc]

Is it really an unobtainable connector? This guy on ebay seems to have access to all manner of sumitomo stuff. He only lists the "popular" stuff but may be worth a try. Link What's the vehicle?

 

It's a 2008 Defender 110. The Sumitomo part number for the housing is 6195-0173 but I certainly can't find a supplier. A few places carry the vehicle loom half but not the male.

 

I was tempted to try the vinegar trick. Might definitely give it a go now!

[DrV]

Depending on how much current it has to carry, you might find that simply crimping a butt splice crimp works ok. It needs to be done with a proper ratchet crimp tool though in order to get sufficient pressure to cold flow the copper. Solder is almost always a bad idea in automotive wiring!

[timsabre]

Has it corroded due to arcing in the connector? A wire which looks corroded over a long distance has often been very hot. Replacing as much of it as possible would be wise if that's what happened

[david.elsbury]

Depending on how much current it has to carry, you might find that simply crimping a butt splice crimp works ok. It needs to be done with a proper ratchet crimp tool though in order to get sufficient pressure to cold flow the copper. Solder is almost always a bad idea in automotive wiring!

I’m about to undertake a repair project on my car, a huyandi Getz- basically there’s a known issue where a plug and socket arrangement for the factory fitted immobiliser becomes high resistance, and the ‘community fix’ is to bypass the plug and socket and solder the wires together.

 

Why is solder not ideal for automotive applications? Is it on the off chance that it gets mechanical vibration and cracks?

[DrV]

Solder's susceptibility to fatigue is the main reason, this can be aggravated by temperature cycling, especially in the engine compartment. Another is damp which can cause problems if flux is not fully cleaned away, or the joint is not properly sealed against it. I accept that there are many solder joints in cars but rarely on wires - usually on PCBs.

 

Edit to add: In your particular application it probably involves just twisting a pair of wires in the same loom together and soldering for durability. I'd use a closed end crimp ferrule filled with silicone grease personally but if you do it right I'm sure soldering it would be fine.

Edited May 25, 2020 by DrV

[Dj Dunc]

This particular plug is the first multipin connector up the cable from the 7 pin towing socket so natural moisture etc has worked its way up the harness from the screw terminals in the back of the 7 pin plug. Going to try and source some spirit vinegar as I've realised that plain old household malt vinegar doesn't have a high enough acid content supposedly.

[Jivemaster]

Is it a connector that you've needed to disconnect many times? Probably you could just cut off some of the tarnished wire with the connector and rebuild the joint without the connector using, solder or crimps or idc connectors with several layers of heat shrink and finishing off with overall adhesive lined heatshrink, or one of the in line cable joiners from B&Q etc.

[Dj Dunc]

Is it a connector that you've needed to disconnect many times? Probably you could just cut off some of the tarnished wire with the connector and rebuild the joint without the connector using, solder or crimps or idc connectors with several layers of heat shrink and finishing off with overall adhesive lined heatshrink, or one of the in line cable joiners from B&Q etc.

 

I had thought about that. I can just put my own 12 way Deutsch DT connector or similar on it, however 1) I don't really want to butcher the factory harness if at all possible and 2) its a pig to get to at the best of times, let alone to solder there.

 

Trying the coke route at the minute which seems to be working. If it solders OK I'll run some current tests through it and see how it reacts.

Edited May 25, 2020 by Dj Dunc