[TowerTalk] PL-239 Going Open?

[Roger (K8RI)]

Bill Aycock wrote:
> Kim (and any others)--
>
> I make assemblies of copper that are normally used in the hand, and I have 
> used lead-free (Tin-Silver Plumbing solder) for assembly. I use both Torch 
> and Irons to make the joints. I have had no problems in several years.
>
> As it happens, my supply of solder in the shack is all Lead-Tin, and in the 
> studio it's all Silver-Tin. It was not planned that way-- it just  happened. 
> The fluxes are different, but otherwise I see little difference in 
> application or use. The only connecter failure I have had recently was 
> caused by a faulty (mine) joint in a lead solder  braid-to-body junction in 
> a tower top RG213 link. It was hell to find because  it was intermittent.
>
> With all the comments I have read about  problems, I have some questions. 
> Many of the comments seem to be "anecdotal" at  best, and I would like to 
> get some facts that can be checked, or traced to sources or Specs.  Hams are 
> notorious for jumping from single instance examples to universal truths.  I 
> know--I  was first licensed in 1952.
>
> Does anyone have data or knowledge of the causes of problems with the 
> Tin-Silver (lead free) solder, particularly in outdoor, Ham  use?
>   
In addition to the TV set problem I mentioned earlier, I've found it 
difficult to work with on small joints and runs with wetting being the 
main difficulty. The TV Repairman said that he had found a lot of 
problems, particularly with "first run" equipment which was produced on 
new assembly lines.

Some one listed the NASA site and "Tin Whiskers". Reading farther they 
have been associated with lead free solder.  Experiments are going on 
showing that only a tiny/trace amounts of lead eliminates them. The 
search is on for a replacement.

The whiskers grow due to an impurity at a specific location on the 
surface. We've done similar work with ultra pure Silicon using molecular 
orientation. With solder it only takes trace amounts of some metals to 
virtually eliminate the phenomena which is the reason I think of them in 
the manner I do. I'd guess the whisker is an alloy that migrates to the 
impurity where the tin is separated from the alloy with the impurity 
acting as a catalyst.

73

Roger (K8RI)