Letter 0014

Gold Electroplating and Pulse Plating

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Q. Hi: I'm a Ph.D student in the chem. eng dept of the university of waterloo , Canada. I am trying to pulse plate gold onto Cu-Be. My gold bath is the typical KAuCN₂ salts in citrate buffer (ie Engelhard E-56 Bath). I am very naive when it comes to pulse plating so please excuse any questions that may seem "stupid". What are the typical "industrial" parameters for a good deposit for gold pulse-reversal plating. My power supply can only go down to msecs for on and off times. Sometimes I also get "shadows" of random dull and shiny regions. What could be some of the reasons? (Note that I apply a layer of Ni onto the Cu-Be before gold plating).

I would also like to obtain a copy of AESF's BOOK: J.C. Puippe and F. Leaman(eds.) Theory and Practice of Pulse Plating [link is to product info at Amazon] , AESF (1986). I called AESF' publication dept. but they no longer sell any copies. Does anyone know where I can obtain a copy of this book. It seems our libraries in Canada do not have this book. Does anyone want to sell their copy? Does anyone have any info on other books about pulse plating specifically gold pulse plating? thank-you

peter kristof
dept. of Chemical Engineering university of Waterloo, Ontario, Canada

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A. Hello, Peter, and thanks for visiting. Used copies of the Theory and Practice of Pulse Plating [link is to product info at Amazon] are sometimes available from Amazon by clicking on the hot linked book title above. Reid and Goldie's "Gold Plating Technology" covers pulse plating at least in passing.

I'm not sure that there are 'industrial' parameters for pulse plating; I don't recall ever seeing an article in a trade journal which presented pulse parameters for an actual industrial application.

I've heard one very knowledgeable researcher claim that the principal thing that pulse plating does is provide agitation to minimize the thickness of the boundary layer, thereby helping to make more ions available for deposition; and that, consequently, over concern about ramp rates & durations can be focusing on distinctions without a difference.

There were many articles on pulse plating published 5 to 10 years ago, and there was an annual pulse plating symposium, but I just don't see as much apparent journal interest today. I'm not saying less is done (probably more is done especially in printed circuit work), but it doesn't seem to be as hot a topic in current journals.

Ted Mooney, P.E.
finishing.com
Brick, New Jersey

I am with Ted on this one. I did work with PR and pulsed current for gold plating at GTE. I never was able to achieve the desired results. I assume you want a more dense deposit. If you are looking for brightness you might want to use a non cyanide gold stripper (jewelry term for brightening) as the Jewelry industry for electroformed gold jewelry.

Gwynne I Edson
- Huntington Beach, California