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[log in to unmask] 8/22/01 3:51:03 PM
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Bill:
Also remember there is ELECTROLESS Gold....as well
as electrolytic, and
immersion....and to answer your question, and another
question on the forum
in the same message....
ABOUT
PLATING...ELECTROLYTIC, ELECTROLESS & IMMERSION...
All plating means
to convert (in chemical terms "reduce") a metal in
solution, also referred to
as a metal "ion", to the solid metal. This means
transferring electrons
to the metal ion in solution...this is true for ALL
plating.
The
difference in the different kinds of plating is the source of
the
electrons.
Electroplating (electrolytic) supplies the electrons
from something the
industry refers to as a rectifier...which could also be
regarded as an
"electron pump".
In Electroless plating the electrons
are supplied by another chemical in
solution, in the case of Electroless
Nickel, it is Hypophosphite, (which,
incidentally, is why these deposits also
contain some Phosphorus.
In Immersion plating, the electrons are supplied
by the substrate dissolving,
and donating its electrons to the metal being
plated....in other words, the
Electroless Nickel (a little bit) goes back
into solution to cause the
(Immersion)Gold to plate.
Note, that with
electroless plating there is theoretically NO limit on the
thickness you can
deposit...and in fact, you can get real thick, if you can
wait long
enough....so, Bill, you can get more than enough Gold using
electroless Gold,
although you for sure cannot using immersion Gold.
In Immersion Plating,
as soon as the substrate metal (in the case we are
referring to here, it is
the Nickel) is covered, plating stops. This is why
Immersion Gold never
gets beyond 10 micro inches thick.
And lastly, understand, that there are
only some kinds of plating baths for
certain metals. There are VERY few
metals that, like Gold, can be either
electroplated, electroless plated, or
immersion plated.
Are we all bored with this now?
Rudy
Sedlak
RD Chemical
Company
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