XPost: sci.electronics.basics, sci.electronics.repair, sci.electronics.design   
   From: excretatauris@invalid.invalid   
      
   On Sat, 18 Jan 2014 20:22:18 -0800, Bob E. wrote:   
      
   > 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.   
   >   
   > I've applied some Kester rosin paste flux as well using my trusty Kester   
   > 60/40 lead-based rosin core solder. No joy. I'm not holding the braid   
   > against the PCB now, I'm just trying to tin the braid and then deal with   
   > melting the 2 solders (on the PCB and the braid) together later.   
   >   
   > My first attempt--before I realized that I was overheating it--I melted   
   > the dielectric insulation.   
      
   Its virtually impossible to tin polyethylene coax braid without softening   
   the dielectric. It will re-solidify. PTFE (Teflon) is better in that   
   respect.   
      
   >   
   > The mesh is made from some silver-colored braid which I thought is   
   > tinned copper but now I'm of the opinion that it's steel; it's certainly   
   > not aluminum. There is also foil which is probably aluminum but I've   
   > trimmed that back and it's not part of this frustrating process right   
   > now.   
      
   If you think the braid is steel, try it with a magnet.   
      
   From a quick look at Belden specs, they, at least, don't make any RG6   
   types with steel braid. There are some versions with aluminum braid.   
      
   >   
   > What's the trick to getting this braid to take solder? I've never seen   
   > this before.   
   >   
      
   If it's aluminum, you can't. Either get some cable with tinned or silver   
   plated copper braid, or put a BNC socket on the PCB, and a crimp BNC on   
   the cable. (I don't trust crimping to aluminum, BTW, there's a   
   metallurgical creep problem)   
      
   --   
   "Design is the reverse of analysis"   
                      (R.D. Middlebrook)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)