In another career - - a long time ago - - almost all our boards were
'flash gold' with thicker hard gold on the fingers. These are electrolytic
processes. The solderability will be excellent because I assume they
will use an electrolytic nickel under the flash gold (usually 2-5
micro-inches of gold). The only issue you might have to deal with is that
the 'flash gold' will be plated before etch and the thicker gold will be
plated after etch. You have to watch for 'slivers' of Ni/au as they can
undercut, and for the activation of the hard gold over the thin gold as it
has now gone through etching, stripping and fabrication.
Happy Holden
Westwood Associates
John Parsons <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
04/19/2005 04:27 PM
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Subject
[TN] ENIG vs Flash Gold
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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