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February 2001

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From:
"<Rudy Sedlak>" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 8 Feb 2001 19:42:02 EST
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In a message dated 2/8/01 9:56:32 AM Pacific Standard Time,
[log in to unmask] writes:

<< Is the immersion tin process the same as electroless plating? >>
This is the only part of your questions that I can answer.  And the answer is
yes, and no.

Immersion plating looks like electroless, sorta, but chemically is different.

Plating is converting metal ions in solution to metal on the board.  Those
metal ions are "converted" by adding electrons to them.  Where those
electrons come from defines the type of plating.
When the electrons come from a rectifier, you have Electroplating.
When the electrons come from another, unrelated chemical in solution, you
have electroless plating.
When the electrons come from the substrate you are plating on to, as the
substrate dissolves, going into solution, and donates its electrons to the
metal already in solution, then you have immersion plating.

The big difference you see is that the immersion bath is one helluva lot more
stable, and easier to run, AND, the plating thickness.  Electroless plating
can, in theory, go on forever, so you can build up any thickness you want.
Immersion plating stops when the substrate gets fully covered (self limiting).

There are NO known Tin electroless plating baths, only immersion Tin.

Hope this helped.

Rudy Sedlak
RD Chemical Company

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