Xref: utzoo rec.ham-radio:22334 sci.electronics:13066 rec.radio.shortwave:2749
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!philmtl!philabs!briar!rfc
From: rfc@briar.Philips.Com (Robert Casey)
Newsgroups: rec.ham-radio,sci.electronics,rec.radio.shortwave
Subject: Soldering to Aluminum, how to do it.
Keywords: soldering trick
Message-ID: <104327@philabs.Philips.Com>
Date: 24 Jul 90 01:26:33 GMT
Sender: news@philabs.Philips.Com
Lines: 27

It is possible to solder to aluminum, using regular rosin-core 
solder.  It just takes a special trick.  
   Reason that you can't usually get solder to stick is that there 
is a layer of oxide on the surface.  Scraping the aluminum in the air 
doesn't work, as new oxide forms within microseconds.  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.  You can 
also use an old screwdriver to scrape under the puddle.  Object is 
to let the hot solder touch un-oxidized alumunum, before the 
air can touch it.  The more scrapes you can make, the more area there 
is to get a good solder joint.  Once you've done this, you'll have 
a spot tinned with solder, that you can solder a wire to.  A good test 
is to tug on the wire to see if it pulls off or not.  You'll need a 
large wattage soldering iron or gun on a large piece of aluminum.
   If you can, solder to a corner, or create a finger partially cut 
away from the large sheet of aluminum to solder to.  Or drill 4 
holes around the spot you want to solder to, then do it.  Object here 
is to avoid losing too much heat due to heat sink action.

 One word of warning: DON'T use a fancy plated soldering iron tip!  I
 did once, and the plating came off, ruining it.  Use an all-copper
 iron or soldering gun tip.

 >> Practice on some scrap pieces before you do this on something important!

	 73 de WA2ISE