Relax Alain :
the original from Martin did have a heading : Rudy, ....... ;
sorry to play a Hawkeye :
but i'd question a need for this kind of "spot" editing .
Otherwise open season , obviously,
just shoot the ducks, not fellows around
thx
paul
-----Original Message-----
From: Alain Savard [mailto:[log in to unmask]]
Sent: Saturday, 1 April 2000 3:15
To: [log in to unmask]
Subject: Re: [TN] gold immersion plating--An attempted explanation
Yes, you are correct. But some variation may be present due to slight
difference in the chemicals involved and exposure time.
Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
e-mail: [log in to unmask]
-----Original Message-----
From: Martin Christie
Subject: Re: [TN] gold immersion plating--An attempted explanation
From your explanation I would assume that this process is self limiting in
terms of the amount of the deposit i.e. where you get the 0.2 micron Gold
deposit from.
Am I correct in assuming this?
Martin Christie
>
>Metals in solution are too low in electrons, and thus have a positive
charge.
> Solid metals, in their shiney form, have the proper number of electrons.
>When a more "active" metal (meaning a metal that does not bind its
electrons
>tightly) is immersed into a solution of a metal that does bind its
electrons
>tightly, like Gold, the electrons shift from the substrate metal, (the
>substrate under Gold is almost always Nickel) to the metal in solution,
>causing the metal in solution to plate out spontaneously on to the
substrate
>metal....in other words, a Nickel coated PCB, when immersed into a solution
>of Gold, will cause the Gold to plate out spontaneously on to the Nickel,
and
>in the process some of the Nickel is dissolved and goes into solution.
>
>This continues until the substrate Nickel is covered, and no more Nickel is
>available for this chemical reaction, and you wind up with around 7-8
>microinches (0.2 micron) of Gold from this type of plating.
>
>Hope this helped...
>
>Rudy Sedlak
>RD Chemical Company
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