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March 2000

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Subject:
From:
"<Rudy Sedlak>" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 29 Mar 2000 09:32:57 EST
Content-Type:
text/plain
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Mr. Stewart:

It is early, and I am just waking up as I type this, and thought I would use
your question as a trigger to discuss the no-accelerator type electroless
Copper plating system.  Incidently, everyone that I know using it loves it,
and says their results are better than using an accelerator, and with good
reason, it is chemically, a better system.

The no-accelerator concept is Shipley "borrowing" a concept that was actually
invented by IBM.  The "best" catalyst is one that deposits the most Paladium,
and removes the most Tin.  The normal Fluoboric Acid based accelerators
remove both.  IBM did some experiments back in the days when they actually
made boards, and purely by accident discovered that the best possible
accelerator was dilute (5%) warm (100 F) caustic soda.  The funny part of
that is they did not have a clue why it worked so well, other than it left
all the Paladium, and removed most of the Tin.
(I talked to the guy presenting the paper about this project, and wound up
explaining the chemistry of his own invention to him!)

The reason why it worked so well is that the Tin left on the board is in the
Stannic state, which is soluble only in dilute caustic, and in HF (Fluoboric
decomposes slightly, releasing trace amounts of HF).  So the caustic
accelerator dissolves the Stannic Tin, and leaves the Palladium behind.

Shipley saw this concept, and simply took it one step farther, since the
electroless Copper bath contains Caustic, and eliminated the accelerator.
Sure Tin builds in the bath, but with bail outs, etc, it never gets too high.

Good system, wish I were selling it.

The really funny part of this discussion is that since I do not have any
commercial interest in the product, such a discussion is okay.  If I were
selling it, a discussion like this would be "Ganz Verboten"....  Rules can
never meet the actual needs of real life.

Rudy Sedlak
RD Chemical Company

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