Mr. Sedlak,

Thank you for your response.  In this scenario, the colloid is not actually
binding to the substrate.  The underside of the trace (EN is a vertical
immersion tank) has a grainy thin deposit.  Keep in mind, this occurs only
on high Tg materials.  Low and high Tg materials can be processed side by
side, and only the high Tg material will exhibit the defect.

Please contact me at 503-357-8695.

Thank you for your interest,

Joel Fillion


At 11:12 AM 3/19/98 EST, you wrote:
>Joel:
>
>We have seen the problem of Shadow plating becoming greater and greater, and
>incidental to some other researches that we have done, know a lot about it.
>
>The problem is caused by the substrate reacting with the catalyst, and
forming
>insoluble Palladium compounds.   When the palladium Compounds get into the EN
>bath, they are reduced by the hypophosphite to Palladium metal, which then
>catalyzes the EN plating.
>
>What to do?
>
>We have solved it, and in fact have a PCB shop using the process.
>
>We have developed a catalyst that will only catalyze Copper.  It binds the
>Palladium so tightly in solution (key word :"solution", not colloid) that it
>will not react/bind to substrate, and will only deposit on Copper.
>
>Would be happy to send you a brochure on this that will explain everything.
>The neat part of this is that you can continue using your current EN and Au
>bath, only change required is in the catalyst.
>
>Better things for better living.... (Thank you Dupont)
>
>Rudy Sedlak
>RD Chemical Company
>Mountain View CA
>
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