Soldering to aluminium - Page 1
Forum section: electronics / general

author: IanB
author_rank: Super Contributor
timestamp: November 05, 2012, 02:52:57 am
content: Occasionally I would like to make a good electrical bond to some aluminium foil or sheet. And having long ago learned about the "solder won't stick to aluminium" problem, I don't even think of soldering. But recently I decided to look more closely.Some searching indicated two approaches:1. Mechanical abrasion to remove the oxide layer and using conventional flux under a film of oil to keep the air away2. Use of a special flux designed to work with aluminium.Approach 1 kinda, sorta, worked, but it was not predictable or reliable. There were many failures for every success.Approach 2 I haven't tried as I have not got any of the special flux.Does anyone have any experience to offer on soldering copper wires to an aluminium surface?Here is an example of the special flux available:http://www.superiorflux.com/aluminum_soldering_flux.htmlThey recommend a tin/zinc solder composition, but say that any tin-based solder should work. The failure of my experiments with common fluxes causes me to be skeptical of such a magic flux. Has anyone tried it?Another problem with my experiments was that my soldering iron tip got coated in black stuff and the solder wouldn't wet it anymore. It was really difficult to clean the black stuff off. Does anyone know if the special aluminium fluxes will still lead to this problem?Any reports of success or failure from people who have been down this path would be most interesting.

author: RCMR
author_rank: Frequent Contributor
timestamp: November 05, 2012, 03:52:12 am
content: I've done it on occasion -- it's not pretty but it's electrically and mechanically "sufficient" in most cases.I use the abrasion method, vigorously scraping the aluminium with the tip of my iron as I feed in the solder and making sure I continue with this until it's obvious that some degree of alloying has taken place -- ie: it's not just some flux holding the solder in place.Practice (and a very hot iron) helps.I have also used the zinc-based aluminium brazing rod but that seems to require significantly more heat than tin/lead solder and the process is the same anyway.The key is to have plenty of heat, lots of movement and a technique which ensures there's always a bit of flux in the mix.I've not soldered to aluminium foil -- I suspect that would be harder because you can't get enough pressure on it to scrape off the oxide without tearing it.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 05, 2012, 04:15:11 am
content: I have used aluminum tape to shield an electric guitar in order to drop the noise floor. I found that for joining the different sections, two pieces of pencil lead (the normal pencil kind) held on top of the join about 0.5cm apart and discharging a 6800uF cap charged to 18V into the leads worked quite well to spot weld the pieces together. (I assume it arcs through the oxide layer and melts a spot of aluminum together.)

author: robrenz
author_rank: Super Contributor
timestamp: November 05, 2012, 04:20:23 am
content: This looks excellent

author: ee851
author_rank: Regular Contributor
timestamp: November 05, 2012, 04:23:29 am
content: I soldered copper wires to an aluminum plate. I used a kit that I bought at a hamfest ten years ago. It worked fine. The copper was still soldered to the aluminum plate last time I looked. If you want, I will see if I can still find the package with the name of the company that made it.

author: Gall
author_rank: Frequent Contributor
timestamp: November 05, 2012, 02:21:26 pm
content: Long time ago I soldered a copper wire to aluminium chassis by using electrochemical copper coating.Recipe:CuSO4*5H2O = 50 g/lNa4P2O7*2H2O = 220 g/lNaH2PO4*2H2O = 15 g/lNaNO2 = 15 g/lpH = 7.5Galvanize (cathode) at 100-200 A/m^2.

author: M. András
author_rank: Super Contributor
timestamp: November 05, 2012, 03:17:50 pm
content: take a look at the multicore alusol solder farnell order code : 629443

author: robrenz
author_rank: Super Contributor
timestamp: November 05, 2012, 03:27:12 pm
content: Here is the pdf spec sheethttp://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=3&cad=rja&ved=0CCoQFjAC&url=http%3A%2F%2Fcommerce.sage.com%2Fbag%2Fupload%2F%2Fsite%2Fdefault%2FFT%2FAnglais%2FMulticore%2FAlu-Sol.pdf&ei=FtqXUIy3B-O_0AGc_4HQAg&usg=AFQjCNFmlKNZIcwGaaykglA4YrvZKaFMHA&sig2=7gvvBPROxSDbFQ9TViX_GA

author: jopki
author_rank: Newbie
timestamp: November 05, 2012, 06:15:19 pm
content: Very long time ago when I was a teenager doing my experiments in my old country in eastern Europe I used then widely available chemical product used for nickel plating called "Niklík" . Not sure what it is chemically but it worked like a charm. Had to immerse the aluminum component into this chemical (I believe it was blue or green colour), heat it up to about 95C (forgot the exact temp) and in about 30 minutes it was ready to be soldered in a completely traditional way, with then usual rosin flux. Done some RF cans that way, aluminum shielding for my projects and even a mechanically sturdy device where tens of kilograms worth of force were repeatedly applied against the soldered joint - a perpendicular bond of a 3mm thick aluminum band and a copper wire 3mm diameter as a handle- no deterioration...

author: nukie
author_rank: Frequent Contributor
timestamp: November 06, 2012, 12:25:31 pm
content: Alusol definitely works with a little bit of scraping with the solder wire. It works for me but I am not sure if its suitable for soldering electronics parts. I am really impressed with the YouTube video posted above showing the magical paste. Definitely going to try it, its gonna help me in a lot of alu soldering.Another method is Ultrasonic soldering with Cerasolzer solder. It is used for solders anything to anything. Abit expensive the equipment, I am experimenting a DIY system with 60khz transducer, as still building the amplifier unit.tapatalk

author: Gall
author_rank: Frequent Contributor
timestamp: November 06, 2012, 12:29:12 pm
content: "Niklík" is something like that?http://www.midwayusa.com/product/119436/caswell-mini-electroless-nickel-plating-kit

author: Simon
author_rank: Unknown
timestamp: November 06, 2012, 12:41:13 pm
content: I used to solder to aluminium earth tags when i was young and foolish till osme one told me it could not be done. It was a pig to do, I'd scrape the aluminium to make it rough and make it very hot and usually it worked after a couple of goes. Needs more heat than electronics parts will take and really I'd not bother again unless i had to and would look at the products advertised above

author: W8LV
author_rank: Regular Contributor
timestamp: September 29, 2013, 08:59:06 am
content: Here is a little trick: use a drop of "3 in 1" brand oil and a hot iron. Just a drop of the oil over the solder. Sometimes it works, sometimes it doesn't. You have to use a big iron, because the aluminium is of course acting like a heat sink. How it works, when it works (I think) is that the oil is excluding the oxygen from the bonding process.. I suppose on this point, its more like Mig welding than soldering.Best Regards from W8LV in Pickaway County, Ohio, USA.

author: Psi
author_rank: Super Contributor
timestamp: September 29, 2013, 09:04:08 am
content: Cheap TIG welder maybe?Yeah, yeah, i know. it's not soldering but a TIG welder is quite a useful thing to have.You can TIG weld aluminium cans together, so thick aluminium foil should be possible.

author: dfmischler
author_rank: Frequent Contributor
timestamp: September 29, 2013, 10:36:33 am
content: Quote from: Psi on September 29, 2013, 09:04:08 amYou generally need AC current to weld the aluminum, and the cheapest Chinese TIG welders are DC only.

author: flolic
author_rank: Frequent Contributor
timestamp: September 29, 2013, 11:03:08 am
content: You can tig weld aluminium with reversed polarity DC.

author: JackOfVA
author_rank: Unknown
timestamp: September 30, 2013, 08:46:10 pm
content: The hamfest aluminum soldering rods are 98% zinc, 2% aluminum and will work with a bit of practice and a deft hand with the torch. Melting temperature is around 750F / 400C. Flux isn't necessary but can be used.There's a kit of solder plus flux intended for the HVAC repair industry - repair of aluminum evaporator or condenser coils - that I've used to solder aluminum sheets together to make simple enclosures. Does a nice job but the kit is on the expensive side. It's also available as a fluxed solder (flux inside a tube of solder, like typical electronics rosin core solder), but I haven't tried that.

author: jopki
author_rank: Newbie
timestamp: January 25, 2014, 01:12:43 am
content: Quote from: Gall on November 06, 2012, 12:29:12 pm.... the colour looks similar. The bottle used to be like $0.25 though back then.