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Soldering Aluminum Wire

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  • Soldering Aluminum Wire

    I know it can be done, but I've never had the need to do it until now. I know there are some special fluxes for soldering aluminum with regular electrical solder, is there any other way or method, tricks, tips, etc.

    JL...............

  • #2
    See here:

    http://bbs.homeshopmachinist.net/threads/50746
    Free software for calculating bolt circles and similar: Click Here

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    • #3
      I have some of that so called aluminum welding rod, Aladdin, Alumaloy and a bunch of other trade names the stuff is sold under, it's mostly zinc I believe and it's much harder than aluminum and after a while it corrodes at the joint, I think it acts an an anode. Since I have to solder copper to the aluminum I'll try tinning the alum. wire with the zinc rod first and then see if it takes the lead alloy solder. I tried the solder under oil method but no luck, just messed up my tip. Evan, I remember reading your post but forgot it contained detailed info on this.

      JL....................

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      • #4
        If the aluminum part is much bigger than the wire you will need a very hot iron. Also, make sure the aluminum is cleaned to fresh metal just moments before soldering. The metal oxidizes starting the instant the fresh metal is exposed to oxygen. It develops a single molecule layer of oxide in a couple of seconds. That is the reason for the oil trick. Apply oil and then scrape the surface clean.
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        • #5
          I'm just soldering two wires togather, one copper and one aluminum. No heavy parts that act as a heat sink.
          I don't know about the oil method, I'm going to try tinning with the zinc rod first and then try soldering to it.

          JL..................
          Last edited by JoeLee; 12-02-2012, 05:17 PM.

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          • #6
            I don't think you can just rub zinc on it. And it won't stick because of the aluminum oxide layer that forms. It would have to be plated. If you make a zincate solution, you can dip the end of the aluminum wire into it for about 15-20 seconds. (Longer is NOT better.) It will remove the aluminum oxide layer and self-plate the zinc. Rinse with water then Let it dry. After that you should be able to solder using a tin based solder.

            To make a zincate solution, you'll need hydrochloric acid and pure zinc. (You can substitute zinc chloride if you have it.) Dissolve about 7 grams (1/4oz) of zinc per 100ml of acid. Take all necessary precautions when working with acid. It will fizz and dissolve the zinc. It will also fizz when you insert the aluminum.

            I use the zincate step when nickel plating aluminum.

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            • #7
              It is very easy to solder the way I demonstrated in the other thread. Nothing difficult about it.
              Free software for calculating bolt circles and similar: Click Here

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              • #8
                Originally posted by CCWKen View Post
                I don't think you can just rub zinc on it. And it won't stick because of the aluminum oxide layer that forms. It would have to be plated. If you make a zincate solution, you can dip the end of the aluminum wire into it for about 15-20 seconds. (Longer is NOT better.) It will remove the aluminum oxide layer and self-plate the zinc. Rinse with water then Let it dry. After that you should be able to solder using a tin based solder.

                To make a zincate solution, you'll need hydrochloric acid and pure zinc. (You can substitute zinc chloride if you have it.) Dissolve about 7 grams (1/4oz) of zinc per 100ml of acid. Take all necessary precautions when working with acid. It will fizz and dissolve the zinc. It will also fizz when you insert the aluminum.

                I use the zincate step when nickel plating aluminum.
                Yes, the zinc rod will stick to the aluminum wire, the question is will the tin based solder stick to the zinc, I think it will.
                I'll post results.

                JL.....................

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                • #9
                  Get a small steel pot. Heat with a propane torch and melt some solder in it. Stick the aluminum wire in the molten solder and just rub the wire with a steel tube brush. It will be tinned, Than take it out and just solder anything to it. The trick is to keep out any oxygen while rubbing the aluminum below the surface of the molten solder. The steel brush will clean the aluminum and the solder will stick to it. This was standard procedure in the old radio industry days. You can do this with any aluminum part as long as you can submerge the section of the part to be coated below the surface of molten solder. All depends on the size of your pot. Keep the solder pot around for whenever you need another aluminum part to be soldered.
                  Last edited by Juergenwt; 12-03-2012, 12:05 AM.

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                  • #10
                    It souond like it would be a bit difficult to try and scrub a piece of wire that is submerged in molten solder. The solder is going to cake to the brush and probably splatter all over.

                    This thought crossed my mind........... how about purging the area to be soldered with argon. Clean the wire under the cover gas and solder under the gas as well. The inert gas should keep the wire from oxidizing as it does steel and aluminum when welding.
                    I guess you could call it helisoldering.

                    JL...................

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                    • #11
                      I assume you are joining the wires for electrical/electronic work. Possibly an RF application. In my 45 years as a TV engineer I have installed and maintained all kinds of equipment from DC circuits to high power RF and microwave. Some of this experience was in areas like Miami where salt spray in the air was a major problem. Many antenna components were made from aluminum and the connecting transmission lines were usually copper. In all that time I do not recall ever seeing a soldered joint to aluminum. Even at microwave frequencies the joints to aluminum components were simply mechanical. The surfaces were flat for intimate contact and were held in contact with some form of screws. Stainless steel hardware was often used. If it was for exterior use, some form of water/weather proofing was used, like an O ring or other sealant. There are sealants made for this purpose: look at an electronic supplier. Aluminum can be connected to aluminum with aluminum rivets and no sealant is even needed. Yes, it will corrode on the outside surface, but if the joint was clean prior to assembly, it remained good.

                      When properly assembled, I never had any problems with corrosion or bad joints, even after years in the weather. Frankly, I think you are only making things more difficult on yourself by insisting on soldering to the aluminum.
                      Paul A.
                      SE Texas

                      Make it fit.
                      You can't win and there is a penalty for trying!

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                      • #12
                        I recommend the Harris aluminum solder kit. It is what the RC guys use to solder up LiPo battery packs. On LiPos one tab is aluminum and one is steel.

                        -Jerry

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                        • #13
                          Originally posted by JoeLee View Post
                          I know it can be done, but I've never had the need to do it until now. I know there are some special fluxes for soldering aluminum with regular electrical solder, is there any other way or method, tricks, tips, etc.

                          JL...............
                          I've got a roll of Alu-Sol right here on my desk.

                          http://www.farnell.com/datasheets/65392.pdf

                          I use it fairly often, not for Aluminium, but for tinning Nickle plated conductors on various sensors and connectors. The aggressive flux cuts through the oxide layer and once I've got things tinned, I clean the solder off and use conventional solder to actually make the joint.
                          Paul Compton
                          www.morini-mania.co.uk
                          http://www.youtube.com/user/EVguru

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                          • #14
                            Harris

                            Here is a pic of a test piece that was soldered using Harris flux
                            http://dl.dropbox.com/u/37105624/20121202_234212.jpg
                            see:
                            http://www.harrisproductsgroup.com/e...inum-Flux.aspx
                            This was done about 15 years ago at a soldering class put on by the copper development institute. I don't know how well it shows up, but there is no corrosion on the test piece after 15 years, The electrical conductivity was the same though the joint as it was across the length of the plate as measured on a Simpson... good enough for the levels concerned I believe.
                            This joint used 50/50 lead solder.
                            As far as electrolysis is concerned... you could have Intergranular corrosion, but electrolysis is reserved for dc current paths through an electrolyte. The metals must be 'connected' through an ionic solution

                            see:
                            http://en.wikipedia.org/wiki/Electrolysis

                            see:
                            http://en.wikipedia.org/wiki/Grain_b...dary_depletion

                            regardless of how you feel about the preceding statement, the test piece that I have in front of me shows no corrosion or deterioration after those 15 years... Your antenna will likely be supplanted by far Superior technology by then...
                            paul
                            ARS W9PCS

                            Esto Vigilans

                            Remember, just because you can doesn't mean you should...
                            but you may have to

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                            • #15
                              I guess since few seem interested in checking the other thread I will post the picture here.

                              Free software for calculating bolt circles and similar: Click Here

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