Re: gEDA-user: Lead Free at home?

[Dave McGuire <mcguire@xxxxxxxxxxxxx>]

On Aug 22, 2005, at 1:02 AM, Marvin Dickens wrote:
> Lead is not the only metal that prohibits the growth of tin whiskers.
> In fact, silver, palladium and copper all prohibit the growth of tin 
> whisker
> as good or better (specifically, Sliver and palladium) than lead. When
> plating copper with tin, you want an alloy of tin that is 93% tin and 
> the
> rest silver or palladium or some other metal. This is true for 
> Immersion,
> electroless and electroplating. When plating copper with nickel, you 
> use
> phosphorous in the same ratio (93% nickel, 7% phosphorous). As an 
> example,
> the following immersion plating solution, if applied correctly, will 
> not grow
> tin whiskers:
>
> 1.) Stannous chloride 3.8 g
> 2.) Silver Chloride 0.25 grams
> 3.) Thiourea 49.5 g (Complexing agent to keep copper from interfering 
> with
>       the tin plating process).
> 4.) 66 degree Baume Sulphuric acid 12 ml.
> 5.) Distilled water 1 liter (1000 ml)
...
...

  Holy Crap.   *boggle*

  Ok, I'm impressed.  The talent on this list is pretty damn amazing.

         -Dave

--
Dave McGuire            "You'll have to be a lot more specific than 
'that
Cape Coral, FL              girl last night.'"    -Ted McFadden