john@frog.UUCP (John Woods) (01/06/90)
Is there any practical way of tin plating aluminum (i.e. Miniboxes) so that it may be soldered? In particular, I just got some Datak TINNIT (a solution for tin-plating PC boards); the ad copy claimed that it "tends to plate any metal more active than tin", so I wonder if it will work on aluminum (though I suppose the oxide coating is likely to defeat this, and even if not, I don't know if the resulting coat would be usable). -- John Woods, Charles River Data Systems, Framingham MA, (508) 626-1101 ...!decvax!frog!john, john@frog.UUCP, ...!mit-eddie!jfw, jfw@eddie.mit.edu Happiness is Planet Earth in your rear-view mirror. - Sam Hurt
whit@milton.acs.washington.edu (John Whitmore) (01/06/90)
In article <11050@frog.UUCP> john@frog.UUCP (John Woods) writes: >Is there any practical way of tin plating aluminum (i.e. Miniboxes) so that >it may be soldered? In particular, I just got some Datak TINNIT... Yes, tinning aluminum is relatively simple; we do it all the time, with aluminum solder. I have had good results with Nassau/Rockmount "Neptune SS" solder and "Neptune Solder Flux", which are used by brushing on the flux, heating the surface with a torch, and adding solder when the flux bubbles. The solder dislikes working, so we often use this solder to tin the surface, then wash off the flux (it's a fluoride flux, so USE ONLY WITH ADEQUATE VENTILATION), and continue the soldering operation with lead/tin solder. Parenthetically, the same solder works on zinc, so it is possible to solder a connection to a galvanized cold water pipe, if you can drain the pipe aforehand. It is simple to solder the seams on a sheet-aluminum box to enhance the RF shielding, as well. It seems likely that TINNIT will work if and only if the surface is cleaned of oxide, because it is an electroless plating compound, and requires metal-electrolyte direct contact. Additionally, I have tried fluxless aluminum solder (the hardware store has it, packaged with instructions for do-it-yourselfers), but never liked it much. Flux helps a lot. I am known for my brilliance, John Whitmore by those who do not know me well.
henry@utzoo.uucp (Henry Spencer) (01/06/90)
In article <11050@frog.UUCP> john@frog.UUCP (John Woods) writes: >... the ad copy claimed that it "tends to plate any >metal more active than tin", so I wonder if it will work on aluminum (though >I suppose the oxide coating is likely to defeat this... Aluminum is actually a fiercely active metal, but that oxide coating is (partly as a result!) just about the stubbornest protective layer you can imagine. I don't think it will work. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
berryh@udel.edu (John Berryhill) (01/06/90)
Try putting on some Hydrofluoric Acid first. -- John Berryhill 143 King William, Newark DE 19711
pekak@nokia.se (Pekka Akselin) (01/11/90)
john@frog.UUCP (John Woods) writes: >Is there any practical way of tin plating aluminum (i.e. Miniboxes) so that >it may be soldered? In particular, I just got some Datak TINNIT (a solution I read in a Great Brittain electronics magazine called 'Elektor' that you can coat the aluminum with corn or olive oil and then scrape it free from the oxide layer. The oil protects the bare aluminum from the oxygen so that it won't oxide again. Now when you have bare aluminum just solder it! Sorry for my bad english. -- Pekka Akselin Nokia Data Systems AB Linkoping, Sweden eMail: pekak@nokia.se Voice : (nat) 013 117715 (inat) +46 13 117715
irwin@m.cs.uiuc.edu (01/12/90)
/* Written 3:30 pm Jan 5, 1990 by john@frog.UUCP in m.cs.uiuc.edu:sci.electronics */ /* ---------- "tin plating aluminum?" ---------- */ >Is there any practical way of tin plating aluminum (i.e. Miniboxes) so that >it may be soldered? In particular, I just got some Datak TINNIT (a solution >for tin-plating PC boards); the ad copy claimed that it "tends to plate any >metal more active than tin", so I wonder if it will work on aluminum (though >I suppose the oxide coating is likely to defeat this, and even if not, I don't >know if the resulting coat would be usable). >-- >John Woods, Charles River Data Systems, Framingham MA, (508) 626-1101 >...!decvax!frog!john, john@frog.UUCP, ...!mit-eddie!jfw, jfw@eddie.mit.edu >Happiness is Planet Earth in your rear-view mirror. - Sam Hurt /* End of text from m.cs.uiuc.edu:sci.electronics */ Many moons ago, in fact in the mid '60s, I designed and built some RF systems for the University of Illinois Athletics Department, such that they could record the heart and respiration rate of an athlete running around a half mile track. The athlete wore a unit battery operated about the size of a pack of cigarettes that had electrodes, etc. The receivers were placed internal to a VM (Voice of Music) tape recorder and were built in a minibox about 2" X 2" X 10". These were aluminum boxes. At the time I built them, I had need to ground to the box at various points to prevent stray loops at high frequency. I located a flux that came in a tube like tooth paste. One cleaned the contact point with aluminum wool, applied the flux and then tinned it. After the initial tinning, a rosin core solder worked very well on it. This has been 25 years ago, and I am sorry to say, I do not remember the name of the product. The point of my response here is to say that it has been done, probably can be still done, if you can locate the correct type of flux. For the curious, the rates were tone encoded, put on reel to reel tape, and the tape was then played into a tone to punch card (what are those :-)) converter. The cards were loaded into a computer to do studies on the abilities of the athletes. Al Irwin, E.E. Univ of Illinois Dept of Comp Sci Urbana, IL irwin@m.cs.uiuc.edu
dmt@PacBell.COM (Dave Turner) (01/13/90)
In article <21000054@m.cs.uiuc.edu> irwin@m.cs.uiuc.edu writes: >stray loops at high frequency. I located a flux that came in a tube >like tooth paste. One cleaned the contact point with aluminum wool, >applied the flux and then tinned it. After the initial tinning, a >rosin core solder worked very well on it. > >This has been 25 years ago, and I am sorry to say, I do not remember >the name of the product. The point of my response here is to say that >it has been done, probably can be still done, if you can locate the >correct type of flux. > It sounds like you're refering to SalMet flux. I thought that I still had a tube yet I can't find it anywhere at home but I suspect that I will. I saw an ad for some in a catalog a few years ago but I'm sorry I can't remember which one. I've checked many of my catalogs at home and can't find it listed. As I recall the ads, it was supposed to allow soldering to most metals. If I do find my tube I'll post the manufacturer's name. And if you manage to find some be sure to heed the warning about adequate ventilation; this stuff puts out some terrible fumes. -- Dave Turner 415/823-2001 {att,bellcore,sun,ames,decwrl}!pacbell!dmt
michael@xanadu.com (Michael McClary) (02/02/90)
Regarding soldering to aluminum: About two decades ago I was working as a techie in a radar lab, and asserted that I could solder aluminum with ordinary rosin-flux 60/40. (I'd figured out the trick, and practiced in advance, so I knew it would work. The professors in charge of the lab, though "knew" it couldn't be done, and got quite a surprise when I did it.) I took some 4" or so aluminum strip, bent the last 1/4" 90 degrees, and clamped it in a vise with the surface to be tinned horizontal. Took a big pyrimidial iron (to have enough heat), laid a BIG blob of solder on the edge, put the iron tip under the blob, and scratched the oxide off. Took several minutes. The blob kept new oxygen away, and tinned the aluminum as soon as the oxide was gone. After doing this to two strips, I sweated them together. Profs weren't convinced it was a real joint until I took visegrips and peeled it apart - which didn't happen until the strips were bent in almost a half-circle. The hard part is getting the aluminum hot enough to tin. It conducts the heat away VERY well. These fluoride fluxes sound a LOT easier.