Xref: utzoo rec.ham-radio:22405 sci.electronics:13093
Path: utzoo!attcan!uunet!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!stda.jhuapl.edu!mjj
From: mjj@stda.jhuapl.edu (Marshall Jose)
Newsgroups: rec.ham-radio,sci.electronics
Subject: Re: Soldering to Aluminum, how to do it.
Keywords: soldering trick
Message-ID: <6073@aplcen.apl.jhu.edu>
Date: 25 Jul 90 16:23:56 GMT
References: <104327@philabs.Philips.Com>
Sender: news@aplcen.apl.jhu.edu
Reply-To: mjj@aplvax.UUCP (Marshall Jose)
Followup-To: rec.ham-radio
Organization: JHU-Applied Physics Laboratory
Lines: 37
Nntp-Posting-Host: stda.jhuapl.edu

In article <104327@philabs.Philips.Com>
   rfc@briar.Philips.Com (Robert Casey) writes:

>It is possible to solder to aluminum, using regular rosin-core 
>solder.  It just takes a special trick....
>What you need 
>to do is puddle some hot solder on the spot you want to solder to.  
>While you are doing that, and the aluminum is also hot, scrape the 
>aluminum under the puddle with the soldering gun or iron.

Yes, this works fairly well when all you need is a good electrical
connection.  However, there also exist solder/flux products specifically
designed for soldering aluminum.  Both Weller (separate solder and flux)
and Kester (flux in core of solder) make such products, and are typically
100% tin with a very active chloride (i.e., acid) flux.  I prefer the
flux-core type, since it does a somewhat nicer job.  The job requires a
propane torch for the high temperatures (~450 F) involved, not to
mention the high thermal conductivity of aluminum.

I made a wonderful and very lightweight 2-meter beam with a shower-curtain
rod, 10-ga. aluminum wire, and the Kester stuff.  I found that when the
temperature is just right, the joints sweat-solder as nicely as
Pb/Sn on copper.  Voila:  no heavy SS bolts, no corrosion problems.

Drawbacks:  Only alloys with a high aluminum content (60-61, 20-24) work
well with the tin solder.  Also, I found it difficult to make
nicely-flowed corners when I attempted construction of an aluminum
enclosure.  Looks like brass, steel, & copper are still the best mat'ls
for homemade boxes.

> One word of warning: DON'T use a fancy plated soldering iron tip!

Ditto with the aluminum solder -- the flux will eat a hole in your soldering
iron tip.  Use a torch.

Marshall Jose  WA3VPZ
mjj%stda@aplcen.apl.jhu.edu  ||  ...mimsy!aplcen!aplvax!mjj