Tinning on old PCBs

From: Dave McGuire <mcguire_at_neurotica.com>
Date: Tue Dec 25 15:09:32 2001

On December 20, John Lawson wrote:
> Just a quick (dumb) question: is this 'tinning' silver? Or Green? In
> other words, has the solder itself actually flaked off the trace (meaning
> it never bonded in the first place) or has the 'paint' coating called the
> solder mask, which is usually green, come off, revealing the trace beneath
> it? This very common, and Ethan is right, it should be carefully re-tinned
> to avoid long-term corrosion.

  I have a bottle of this really neat stuff that I bought at Active
Electronics when I lived in Maryland. It's a clear liquid that, when
brushed or poured over copper, deposits a layer of silvery metal (tin
I assume) on the surface of the copper...nearly instantaneously. It
just seems to plate out of solution onto the copper. It's most
interesting to watch. It was sold with the printed circuit board
fabrication materials, obviously intended for post-etching tinning of
the remaining copper.

  I don't quite recall what it was called; it's still packed up from
my move. But it was really neat stuff.


PS - Happy holidays to all my fellow classiccmp'ers!! May your days
     be filled with tons of good food and your nights be filled with
     blinkenlights and elegant non-x86 instruction sets.

Dave McGuire
St. Petersburg, FL         "Less talk.  More synthohol." --Lt. Worf
Received on Tue Dec 25 2001 - 15:09:32 GMT

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