Yes, true, what Dave said.

-----Original Message-----
From: Rex Waygood [mailto:[log in to unmask]]
Sent: Thursday, February 02, 2012 11:41 AM
To: TechNet E-Mail Forum; Guy Ramsey
Subject: RE: [TN] ENIG thickness

Umm
This assumes the gold evenly distributes through the cooling joint.
I have seen failures at <1% which although not confirmed to be gold
embrittlement went away when we took the pragmatic decision to get rid
of the gold.
Rex


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: 02 February 2012 16:25
To: [log in to unmask]
Subject: Re: [TN] ENIG thickness

Under normal conditions all of the gold protecting the base metal should
dissolve into the solder.

For ENIG, the gold plating process produces a thin layer of gold that is
entirely dissolved. The solder connection is to the nickel.

Many connectors have electroplated gold that can be much thicker than
the ENIG process we see on bare boards. Check the data sheet.
Then, consider the requirements in J-STD-001, with the knowledge that
gold makes it brittle. I've seen white papers that suggest degradation
begins about 2%, though there is a consensus that it should not exceed
4%.

There are threads in the archives discussing the condition.


-----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,