The reasons for the request being the difficulty in protecting the
selective gold during the EN process - generally done with photo resist,
but this will breakdown in the elevated temps of the EN bath.  The flash
gold process will certainly give you areas above the thickness of the IG
- electrolytic AU will have differentials in thickness due to circuit
geometry, which can be fairly drastic depending on the PCB design.  You
may want to look at using IT or IS in place of ENIG. 

Jeffrey Bush
Director, Quality Assurance and Technical Support

VERMONT CIRCUITS INCORPORATED
  76 Technology Drive - POB 1890
    Brattleboro, Vermont 05302
      Voice: 802.257.4571.21 Fax: 802.257.0011
           http://www.vtcircuits.com
 

-----Original Message-----
From: John Parsons [mailto:[log in to unmask]] 
Sent: Tuesday, April 19, 2005 4:28 PM
To: [log in to unmask]
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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