Pulse Plating of Gold: harder deposits, smaller grain, less porosity, better wear?

A. Hi JP. Copies are occasionally available on Amazon and Abebooks, although it appears that today there is one copy in German on Abebooks and none in English.

But try worldcat.org which will tell you which of the world's libraries have copies. Apparently there are at least a dozen copies currently in US libraries, although none closer to you than Pennsylvania :-(

Luck & Regards,

A. Hello, Peter, and thanks for visiting. Used copies of the Theory and Practice of Pulse Plating [adv. this book on eBay, Amazon, or AbeBooks] are sometimes available from Amazon. Reid & Goldie's "Gold Plating Technology" covers pulse plating at least a little bit.

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 actual mass-production industrial applications.

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, being overly concerned 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.

A. 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.

A. Yes, it probably does, Gary.

The disruption in the current, followed by a sudden surge, causes new grains to form, resulting in a smaller, harder, structure. Much has been published on the general idea of pulse plating, but it is yet another variable in a very complex system. A literature search keyed by gold and pulse should give you dozens of articles.

There is a book on the subject, "Theory and Practice of Pulse Plating" [adv. this book on eBay, Amazon, or AbeBooks] by Jean-Claude Puippe & Frank Leaman, but it is out of print and sometimes hard to find. Perhaps even harder to find is Dr. Ned V Mandich's presentation "Pulse Plating of Acid Gold for Electronic Contacts" from the AESF 4th International Pulse Plating Symposium, (Orlando), 1990"

Rectifier manufacturers can probably provide "case history" flyers about pulse plating.

A. Pulse plate it. There are hundreds of articles available on this exact subject. The AESF is a good place to start your investigation(links available from this site) along with Metal Finishing magazine. AESF will do lit searches for you. Pulsing in the tenths of milliseconds range may yield the desired result, or you can get special pulse units that can do hundredths of millisecond pulses. Contact Dynatronix Inc for power supplies.

Regards,
Dave,

A. I would be cautious about this. Your customer should tell you how he measures wear resistance of the gold and then you should see how your gold stands up to this test. Also, you need to find out if anyone else can or does supply this more wear-resistant gold. You can check with the vendors of gold plating solutions, but the use of standard abrasion tests don't always correlate with real world results, so you don't want to chase a mirage.

A. You can do electrophoretic lacquer over the gold plating, yes it will add time i.e., more process, but it will be much much cheaper compared to gold with added wear resistance.

I thank you for your responses. Unfortunately clear E-Coat is not an option in this case. Furthermore, my customer measures the wear of the gold only in the real world. this is why I am looking for testing procedures and apparatus that will help me quantify the wear. I realize that there are few if any tests out there that correlate to the real world but if a test will give me numbers that that shows my product wears twice as long as the other guy then that is all I need.

A. No it is not a must. The digital is finer control only. Gold plating, usually over nickel, takes less than a minute, so you need high current plating solution only if your output is big.
Gold plating is soft and not wear resistant and for better resistivity a gold alloy plating is used, and maximum thickness you can get is important too.
Good luck.

A. Hello D. If all the other plating parameters are thoroughly understood and under close control … then, yes, pulse plating can probably improve the deposit. But taming all of the variables is not easy, and if the other parameters are not yet fully understood and controlled, then pulse plating is yet another dangerous loose cannon in your process :-)

It can work, but it's fine tuning.

A. There's some studies on hard gold pulse plating for connector parts with a pulse period of 0.01 to 0.1 sec and a duty cycle of 1 to 10% which show improvement to certain extent on compressive stress of gold deposit due to increase in gold crystalline size.

A. Hi Vic. I'm not sure what you are referring to when you say "I know nothing about this". If you mean you are unfamiliar with pulse plating, but you are experienced in gold plating of jewelry, then David's response may be be what you are looking for.

If you mean you are unfamiliar with plating in general, then the right answer is probably 100% on-time / 0% off-time because introducing pulse plating to a process which is not under control and well understood will do nothing but make it worse. Good luck.

Regards,

Q. Is there a book for dummies on pulse plating or a place where I can take a course on how to do it for gold plating and electroforming gold? I have gold plated using the normal rectifier, now I would like to learn how to do this with pulse plating gold jewelry.

What I am looking for is some parameters where I can start at to pulse plate a 14,18, karat gold and also to electroform 14 kt and 18 kt gold. For parameters I am asking for some starting points in milliseconds on and off and also amperage I would use per square inch when I try to electroform gold. Any help would greatly be appreciated. Also any info on anybody's solutions that they sell for these purposes.

Thanks