PSN-L Email List Message

Subject: Re: Silver & soldering pad tips...
From: "Erich Kern" efkern@.............
Date: Sat, 9 Feb 2002 11:52:51 -0800

My apologies to those list members who find this somewhat off topic, but some find it


I agree with Charles that the dime was dissolved in the molten solder. Long ago, I
made some small metal sculptures using pre-1964 silver quarters hammered flat then cut
into strips with tin shears. Since I didn't have a very hot torch at the time, I used
60-40 solder to start the process, the thin strips of coin silver were partially
dissolved in the solder, which raised the melting point of the molten mix, but when
finished, enough silver went into solution that the finished product had the
characteristic color of silver, which is similar to pure tin in color, but tin doesn't
tarnish to black the way silver does.

Pre-1964 dimes, quarters and half dollars are 90% silver, 10% copper. Sterling silver
is 92.5% silver, 7.5% copper. The leads on older rectifier diodes were silver plated,
soft drawn copper, I doubt they were pure silver.

Erich Kern

----- Original Message -----
From: "Karl Cunningham" 
Sent: Saturday, February 09, 2002 8:48 AM
Subject: Re: soldering pad tips...

Charles --

Sounds plausible, but I'm not so sure.  Some rectifiers used to have silver
leads for improved heat sinking, or so the manufacturers said.  The leads
did have the look of silver and were VERY soft and often tarnished, but
they didn't dissolve into the solder (at least not enough that you'd
notice).  I do know that dissolving of copper into solder is a problem, but
only with very fine wire (~#44 & smaller).

Anyone care to try the old dime test?1

Karl Cunningham

--On Friday, February 08, 2002 09:33 -0800 "Charles R. Patton"

> Bob Shannon wrote:
> "So I heated the solder to see what had happened....Guess what? NO
> DIME."
> My guess is that the dime went into solution.  Dimes were silver which
> is very soluble in lead/tin (solder.)  This is why there are solder
> alloys with  1 to 2 % silver available for electronics, primarily SMT
> components which used to commonly use silver terminations, in order to
> avoid dissolving the termination when the component was soldered on.
> Charles R. Patton


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