Daniel,

I was going to respond to Werner's, Gerard's and Richard's responses but
decided not to.  I would however, like to totally agree with your
comments.  Those of us who do failure analysis on electronic products
certainly know about brittle solder joint failures.  The surface finish
chemistry suppliers and board fabricators have done a good job of
decreasing the occurrences of brittle solder joint fractures associated
with ENIG.  I'm not going to use the "color" pad name for the ENIG
failures because that name does not describe the failure mode or root
cause.  The IPC-4552 document is a good guideline for those using ENIG
boards and if followed will help keep the occurrences of failures at a
low level.  The brittle failure problem associated with ENIG is an
extremely low level problem but when the problems do occur they usually
happen at the worst possible time.  There are at least four major
corporations that produce electronic product that I know of that have
banned the use of ENIG because they experienced brittle solder joint
failures.  I should also point out that they were not using schlock
board houses.

Fortunately the surface finish of choice in our company is not ENIG and
I have not had to recently deal with many brittle solder joint failures.
There have been a few analysis we've done on legacy products that are
ENIG that have indicated brittle solder joint fractures.  I know how
busy those who work in failure analysis have been and I expect the
volume of brittle solder joint failure to increase (not because IPC-4552
isn't a good guideline) because the thermal/mechanical stress level on
solder joints as well as the stiffness of solder joints will increase as
we move to Pb-Free assembly.  


Regards,
George
George M. Wenger
Reliability / FMA Engineer
Base Station and Subsystems Group
Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Daniel Blass
Sent: Friday, May 12, 2006 9:30 AM
To: [log in to unmask]
Subject: Re: [TN] Question about ENIG in SnPb process . . . .

Board vendors love to claim they've fixed ENIG's problems but don't
believe them.  We routinely see ENIG problems in our failure analysis
work.  The bottom line is that using ENIG will give assembly and
reliability problems sooner or later, regardless of your supplier.
Other than that, ENIG is a delight to work with and every other finish
has some assembly or reliability drawbacks.

Daniel Blass
Process Research Engineer
Area Array Consortium
Surface Mount Technology Lab
Universal Instruments Corporation
http://www.uic.com/wcms/WCMS2.nsf/index/Global_Svc_Support_31.html

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