# Soldering to aluminum



## marschw (Jul 13, 2008)

Any advice on soldering to aluminum? I can never seem to get it to stick; what sort of fluxes/solders/temperatures should I be using? And where can I get them?


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## labrat (Jul 14, 2008)

http://www.aws.org/wj/2004/02/046/

Internet is an abundant source of information!
Biggest problem seems to remove and avoid new build-up of aluminium oxide on the surface where you want to solder on.
You might need some acid solution, do your search and read up on the net!
I know there was some paste available before, long time ago, might not be available/not allowed because of some now illegal additives!
Cannot find it, probably been thrown in the trash some years ago.

Hope this does for some help!


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## precisionworks (Jul 14, 2008)

Stop by a local welding supplier & buy a bottle of Aluma-Kleen (acid etch). Wear gloves & eye protection as it is nasty stuff. Follow the directions, rinse, dry, scratch with a SS toothbrush, wipe with acetone, & solder immediately. Waiting even a few seconds allow the Al Oxide to start reforming.


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## marschw (Jul 14, 2008)

precisionworks said:


> Stop by a local welding supplier & buy a bottle of Aluma-Kleen (acid etch). Wear gloves & eye protection as it is nasty stuff. Follow the directions, rinse, dry, scratch with a SS toothbrush, wipe with acetone, & solder immediately. Waiting even a few seconds allow the Al Oxide to start reforming.


Thanks. Is this process in addition to, or instead of using flux? From what I've been able to tell via Google, is the Aluma-Kleen being used just to de-oxidize the aluminum? Could I use DeoxIT instead?

Also, wouldn't the flammability of acetone be a problem if I solder to aluminum immediately after wiping it with acetone?

Will normal 60/40 solder work with this process?


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## precisionworks (Jul 14, 2008)

The Aluma-Kleen physically removes the oxide layer ... leave a part in long enough & it disappears

I use it before GTAW welding aluminum ... first the cleaner, then the SS brush, then acetone wipe, weld immediately. The acetone vaporizes about as fast as you can blink your eyes. It's a widely used industrial cleaner, but you should follow normal solvent precautions per the MSDS:

http://www.jtbaker.com/msds/englishhtml/A0446.htm

I've never soldered Al, always welded it. Can't advise on fluxing or not.


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## X_Marine (Jul 15, 2008)

Some good info here, thanks.

Welding to aluminum is a little difficult in it self, I'm not sure but I don't believe soldering to alum is actually possible. Aluminum is a terrible conductor of electrical current as was discovered yrs ago using it for wiring in homes etc. But it is a wonderful conductor of heat which makes welding cutting almost impossible. A gouge arc is normally used for cutting because it heats the alum very fast with an arc and then blows the molten alum away with high pressure air IIRC. Makes an awful loud sputtering sound.

Before actually learning to weld with B&R I once tried cutting a large hole in a beer keg I used as a creeper. I had drilled and installed casters on the bottom and stuck a piece of carpet on the top. ')
One evening I decided that if I cut a hole in this thing I could keep my tools stuck under my seat. Sounded good until on this hot Houston night, wearing shorts I fire up my cutting torch and straddle this thing lying on the floor and after cranking up my Ox Ac a cpl times for a really large hot tip which I held in place for way to long with no apparent results other than to teach me how well alum can dissipate heat. After ??mins I finally got the message on the tender inside portion of my legs as I jumped off that thing like it was a HOT bull.. lmao No real damage done but lesson learned well. 

Sry for ramblin but my point was that you will prolly have very little luck in soldering.

I might suggest if possible, drill and clean well and install a brass screw or similar that you can solder to if a physical connection won't work.

Keep in mind that this is all from an old archive in my head and today almost anything is possible. I'm glad to learn of these new products as I may need them myself down the road.

Hope maybe that help a little. Good luck 
X/BillyD..


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## marschw (Jul 15, 2008)

X_Marine said:


> I might suggest if possible, drill and clean well and install a brass screw or similar that you can solder to if a physical connection won't work.


Ah-ha! That sounds like it'll work for my purposes. I'll give that a try.


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## will (Jul 16, 2008)

X_Marine said:


> ...Aluminum is a terrible conductor of electrical current as was discovered yrs ago using it for wiring in homes etc. .




The aluminum wire was not the problem as far as conductivity. The issue was the oxide that formed where the wire was attached, many house fires were started from arcing near the outlets and switches. The fix was either to rewire the entire house or to install 'pigtails' of copper wire for every connection to a switch or outlet. I think that the oxide was not as great a problem between the aluminum and copper held together with a wire nut, but was greater when the aluminum wire and the steel screw were used in the outlet. This may have been a result of 'literally' some loose screws making connections.


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## frenzee (Jul 18, 2008)

I've used this (aluminum version):

http://www.solder-it.com/solderpaste.asp?

Works pretty well.


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## VegasF6 (Jul 18, 2008)

will said:


> The aluminum wire was not the problem as far as conductivity. The issue was the oxide that formed where the wire was attached, many house fires were started from arcing near the outlets and switches. The fix was either to rewire the entire house or to install 'pigtails' of copper wire for every connection to a switch or outlet. I think that the oxide was not as great a problem between the aluminum and copper held together with a wire nut, but was greater when the aluminum wire and the steel screw were used in the outlet. This may have been a result of 'literally' some loose screws making connections.


 

I was always under the impression that the problem with aluminum wired houses was expansion. The aluminum wire at a steel junction expanded at different rates and the aluminum wire was brittle, could crack or break. But then, perhaps that was one of those old wives tales. I just remember people using it as an argument against pre built modular homes, that they weren't wired with copper. But that too is probably outdated.


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