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How Does Flash Gold Plating for PCBs Work?

Hi,

I would like to get a better understanding how electrolytic plating works.
Flash gold, being an electrolytic process, an electric current is required to plate the gold onto the board. How will this be implemented in the industry? Will all the pads and traces of the PCB have to be connected electrically? As not all pads and traces are connected together, how will this be achieved?
Any help is welcome!
Thanks!

Horst Space
Electronic Design - Munich, Germany
2005

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First of three simultaneous responses --

Electrolytic Au has been plated on printed circuit boards for many years. What type of boards do you or your company design? There are single and double sided, multi layer, blind and buried via multilayer, surface mount technology and the list goes on. "Flash Au" is usually applied today by immersion (without current). You can selectively coat the board with approved photoresists and achieve the Au coating wherever you want, or the entire board if you want. Not many PC board shops across the country have this process in house. Multi layer boards are easier to electroplate in Au because signal layers are connected by the plated through hole where you can maintain that interconnection. Let me know what type of boards?

Mark Baker
process engineer - Malone, New York
2005

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Second of three simultaneous responses --

There is also electroless technology. You may want to read about it. No current, only chemical reduction. Several metals can be deposited including nickel, gold, copper, etc.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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Third of three simultaneous responses --

The PC board is fabricated with a shorting bar that connects all plug-in tabs. Then after plating the shorting bar is cut off.

Another way is to mask the board (or control depth) and plate the fingers before the board is etched.

Be sure to put nickel under the gold to help stop the copper from migrating right thru the gold.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2005