XPost: sci.electronics.basics, sci.electronics.repair, sci.electronics.design   
   From: andrew@cucumber.demon.co.uk   
      
   In article ,   
   	John G  writes:   
   > Ralph Mowery expressed precisely :   
   >> "Steve"  wrote in message   
   >> news:87egc65xql.fsf@centurylink.net...   
   >>> Bob E.  writes:   
   >>>   
   >>> < I am trying to solder some RG-6 shield to a pcb. The braid won't tin.   
   >>> It's   
   >>> < almost like it's dissipating the heat faster than I can apply it. With   
   >>> both a   
   >>> < temp-controlled iron (set as high as 700F) and a mondo 100W stick I   
   >>> finally   
   >>> < tried. The solder will barely melt when touched to the braid opposite the   
   >>> < iron.   
   >>>   
   >>> That just sounds like another excuse to the use the butane torch :)   
   >>>   
   >>>   
   >> Most of the rg-6 uses aluminum instead of copper or tinned copper.  The   
   >> normal methods of soldering will not work on it.   
   >   
   > I'll believe Aluminium or steel I must admit to only a little actual   
   > experience.   
   > Some Cable guy should give an actual answer.   
      
   Ordinary soldering can be used with iron - soldering iron bits are   
   often copper core for thermal capacity and conduction, with iron   
   plating which wets well with solder but doesn't oxidise/corrode   
   as quickly as a bare copper bit does.   
      
   As you go to steel and then stainless steal, it gets harder to do.   
   Stainless steal in particular is protected from corrosion by a very   
   tough layer of chromium oxide (I don't know if it's possible to   
   solder stainless steel at all).   
      
   Aluminium has a similar problem - a very tough layer of aluminum   
   oxide which needs a suitable flux to strip through. However, it also   
   needs a different solder alloy to wet it - it's a long time since I   
   did it but ISTR using a solder alloy containing silver.   
      
   A secondary problem with soldering dissimilar metals is that any   
   moisture risks causing galvantic action/corrosion of the join, and   
   in the case of aluminium, this happens even between the aluminium   
   and the solder used. Selecting a flux which can strip the aluminimum   
   oxide well whilst not leaving any residue which eventually corrodes   
   the join is a bit of a challenge.   
      
   --   
   Andrew Gabriel   
   [email address is not usable -- followup in the newsgroup]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)