soldering aluminum

I used to solder ground lugs onto an aluminum chassis using a regular soldering iron, solder and a small stainless brush. Melt a puddle of solder and then keeping it liquid scrub it onto the aluminum. The stainless brush removes the oxidation under the melted solder and the solder adheres.

Cheers,

Bruce (bruceinbangkokatgmaildotcom)

should

The technique is to clean the aluminium, then solder through a puddle of high temp oil - I use silicone oil only as I have some left over from a photocopier. You will need to form a bead of solder on the iron, and then scratch the aluminium through the oil with the iron tip.

The issues with aluminium are twofold: a/ it is highly reactive so oxidises as fast as you clean it - the oil keeps the oxygen at bay. b/ It is highly thermally conductive, so you need a powerful iron to get the local bit to soldering temp

AWEM

On Jun 20, 1:18=A0pm, JIMMIE wrote: but I need to know what gas I should

Argon is the most inert gas. Nitrogen is a close second. CO2 is not inert at welding temperatures, but should be fine for soldering. Natural gas would work, but it is flameable so I would not advise using it. Ditto Propane. Or do as the others have suggested, and do the tinning under oil or solder.

=20 Dan

I have used the suggested methods using oil and solder but they are not suitable for my needs. The solder only bonded to the Al along scratches made on the Al. I am going to try some CO2. I figure a few small pieces will yield enough gaseous CO2 to displace the air in the glove box 100 time over then I can use a rotary tool to remove the oxide and conventional soldering procedures. Im am not interested in soldering two pieces of metal together at this point. I only want to tin the AL which will allow me to solder a conductor to it using convential means later on in the constuction process.

Jimmie

A high tin solder will solder much easier as well.

In fact, you can in most hardware stores find in the soldering / brazing area - a silver box - for soldering Aluminum.

I've done both - puddle of solder - with a 150W black beauty iron and used the special tin solder with flux. The flux provides a seal.

Martin

Andrew Maws>> I need to solder to an aluminum tube for an electrical connection. I

Yes, dry ice ought to work well. I also thought burning something in the glove box might work to get rid of the oxygen.

Dan

I'm surprised that nobody has mentioned All-State #509 soldering flux, available through Esab.

Works like a charm soldering copper to aluminum, among other things. Pretty aggressive stuff though, so be sure to clean it all off after finishing the solder joint.

Data sheet at

Carla An armed society is a polite society. Robert A. Heinlein

I've done the "scratch under a pool of molten solder" technique, and it works fine. Clean up the Al as best as you can beforehand.

Jon

And tin solder works better than lead or electronic solder. You can buy it at the hardware store in the brazing and welding area. Also on-line.

Mart> JIMMIE wrote:

Back in the days of tube radios when the chassis was grounded I used to use regular resin core solder, the same stuff I was soldering wires with, to make connections to an aluminum chassis. Just rubbed a spot with emery cloth to get it shiny and puddle some solder onto the spot and rubbed through the molten solder with a little stainless brush. I don't know how strong it was structurally but it certainly held a solder lug to make a ground to.

Cheers,

Bruce (bruceinbangkokatgmaildotcom)

No doubt Bruce - I was into steel chassis and finally the light weight Al ones. I said better. Tin is the issue - electronic was 63/37 and the like. 37% tin.

When you buy Al solder, you get special fluxes that etch oxide and keep air off it.

Mart> >

True.

I was simply trying to point out that sticking something to aluminum is not "rocket science" but can be accomplished with normal materials. Now.... if it were some sort of structural joint it would be a different story..

Cheers,

Bruce (bruceinbangkokatgmaildotcom)

I finally got around to trying soldering Al in a CO2 atmosphere and the solder took well but my setup is a little awkward to use because my gloves for my glove box are a little stiff. I also found I need to vent my box as the pressure built up from the dry ice evaporating tends to push the gloves out of the box. I think I used WAY too much dry ice. The object soldered was a small AL rod about 3mm in diameter. After the process was completed it was soldered succesfully to a brass tube in a normal atmosphere.

Jimmie

I have tried various solders/fuxes that are suppose to allow you to solder to Al. In my case this means tinning the Al so that it can be soldered to easily by a relatively unskilled person. None have produced a suitable bond for this.

Jimmie

Without knowing your usage I'd think that bonding the parts using an adhesive would be satisfactory (depending on area of bond, of course). They have been "gluing" airplane bits together for some years now :-)

Cheers,

Bruce (bruceinbangkokatgmaildotcom)