Victor,

If you go back to Wally Bader's paper that he published in The Welding Journal when he was working for AT&T, which I refer to as "The Dissolution Bible", you will see that gold dissolves in 450F SnPb solder at a rate of 117.9 microinches per second.  Therefore the gold on an ENIG plated surface with 4 to 5 microinches of gold will be gone in 0.03 to 0.04 seconds.  I don't think you can realistically make the gold thick enough so that it won't be totally consumed in a soldering process.

Regards,
George
George M. Wenger
Senior Principal Reliability / FMA Engineer
Andrew Corporation - Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Thursday, February 02, 2012 10:38 AM
To: [log in to unmask]
Subject: [TN] ENIG thickness

Fellow TechNetters:

   At what ENIG thickness will the gold not be totally consumed by the soldering process on a connector lead, LF solder joint.   What happens when the gold is not consumed.  Will the joint structure be compromised.   What about the IMC formation.  The SJ strength.

Victor,