Solder to Aluminum?

Depends somewhat on the size of your wire. There are various fluxes containing fluorides that can work on aluminum.

There's some stuff called "solder-it" or "Kool-it brand" made by universal corporation. They have a lot of specialty soldering stuff.

There's some aluminum welding rod called Welco 52. Can get it at any welding supply house. Made for low temperature welding of aluminum pieces. Also sold in hardware stores as no-flux aluminum solder or brazing rod.

If your wire is big enough, you can use the Welco 52 and a torch to "tin" the wire. Then you can solder to the Welco 52 coating. I've used that technique to make aluminum resonant cavities that I could assemble with ordinary solder.

Voice coil implies motion. Aluminum doesn't flex well. Make sure the aluminum part stays rigid. mike

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That would be a nice way to do things, if there was enough space. But the coil terminations are about 4mm long, recessed in a notch in the aluminum coil former. I have existing coils that I wish to rebuild, that were soldered, so I know it can be done.

Thanks for the input.

Good day!

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Spot weld the aluminum wire to copper wire. If you don't want to spot weld, then use crimp hardware designed for aluminum/copper connections. Then solder the copper wire to whatever.

Al

cant say if this is suitable or not, but the soldering iron tip wetter/flux/solder paste has an extremly active flux, ive used it to solder nichrome wire onto a pcb before, i did have some aluminium solder too but dont think i had much luck with it.

Colin =^.^=

I'd say 'forget it'. There are solders that will join aluminium to copper, but most involve an intermediate alloy, and some fairly nasty fluxes, and are usually at the higher temperature end of normal soft soldering temperatures. Have a look at:

and look at Tra-Duct 2902. This could be ideal for the application.

Best Wishes

There are quite a few metal filled epoxies around. Some with quite low resistance (the silver impregnated ones). Check the industry for those and then there's always:

Robert

You are on the right track: don't let the Al2O3 reform. Instead of vacuum/inert gas, I had good luck with soldering under a droplet of engine oil. I was soldering to a 1mm by 1 cm Al strip, using a small 30 W iron; I wetted the tip with a blob of solder, and touched the side of the oil droplet, while scrapping the area covered by oil with a dental pick. Within 10-20 seconds, the solder wetted the scratched area under the oil.

JB Weld is excellent to hold things together. BUT. It is a darn good *insulator*.

Over 40 years ago, i wanted to solder to aluminum, and so bought some special solder for that, useable with ordinary solder irons. A bit problematic, as it had chromium (if i remember correctly), and the fumes were toxic. Worked *very* well; in fact, too well if the aluminum was too thin; the alloy crept underneath the oxide skin and leached the aluminum, making it thinner if one was not careful. The basic secret to soldering aluminim, is getting underneath or thru the oxide skin without allowing the aluminum to protect itself by creating new oxide. One can use ordinary electronic solder, and a rather active flux to break down the oxide and cover the area from oxygen. Once there is a break, the solder will *very* easily flow underneath the skin (makes it bulge as the solder flows underneath). The solder will quickly flow over the are wheer it is hot enough to keep it a liquid. So if you can heat a local are just enough to get that break, and quickly wipe the oxide off as it cools, then one can later do a quick solder of a copper wire to that area. Practice a lot on first a 1/16th inch sheet and then on similarly sized wires before doing the real thing!

Well, I use Alusol from Multicore. It is listed for example at

(search for Alusol). Melting point may be rather high perhaps - and the website says not suitable for electrical joints - but it works for me.

Solder in an inert atmosphere/vacuum, maybe?

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No need for that extreme; most liquid fluxes stay around and keep the oxygen out.

OIL! Did not think of that. Forgive the pun, but that was a slick idea!

There is an alloy from Indium Corp that is 91Sn 9Zn which can solder Al with a flux. I'm waiting for them to get back to me.

I can't find a US distributor of that Alusol anywhere. Thanks for the link, though.

Good day!

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I haven't done it in years, but I recall a block of some substance with which you abraded the surface of the aluminum and then you could solder to it in a normal fashion.

...Jim Thompson

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The technique I've read for soldering to aluminum with zinc alloys is to melt a blob of solder onto the aluminum and then to keep scratching back and forth at the bottom of the puddle with the soldering iron tip. This scratches through the aluminum oxide layer and exposes fresh aluminum which the solder bonds to, while the puddle of solder itself keeps oxygen away.

-- Regards, Carl Ijames carl.ijames at verizon.net

Might be sal ammoniac also known as ammonium chloride. You used to be able to buy them at Sears many moons ago.

Al

[...]

You'd think a bullet hole would mean a ruined engine and a crashed plane.

Where and how can you put a hole in an engine without destroying it?

Mike Monett

hole

I knocked a hole in the oil pan of my truck. Was not destroyed. Wasn't a bullet hole tho...unless it was a really big bullet. mike

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