John:

In my mind the quality/thickness of the gold is the lesser important difference than the fact that with ENIG your trace, and all surfaces are completely covered with ENIG, this will not be the case with electrolytic processes... With electrolytic plating you will have exposed Copper on the sides of the traces.  The trace is plated ONLY on top with Nickel and Gold, with the sides being exposed Copper.  The potential for some serious galvanic corrosion is high.  This may not be an issue in your case, and certainly H-P shipped a whole lot of equipment made with boards like this, but you should be aware that if your boards operate in a corrosive environment, this certainly puts them at risk.

Rudy Sedlak
RD Chemical Company

John Parsons <[log in to unmask]> wrote:
We have sent a board to our off-shore vendor for fabrication. The pcb
finish is spec'd as immersion gold with selective hard gold. Our Chinese
vendor has come back asking if they can process as flash gold with selective
hard gold.



Correct me if I am wrong as I have seen "flash gold" and "immersion gold"
referenced as the same process but I believe that flash gold is an
electrolytic process is it not? I am leaning towards approving this request
but is there anything I should be aware of or question before I do so? Any
"gotchas"? From what I have read "flash" gold can be process as either hard
or soft. Can I assume that if they are going to use it to replace immersion
gold that the finish will be comparable for solderability?



John Parsons




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