Thanks George for
your feedback,
The "black pad"
diagnostic has been established by our EMS provider and "acknowledged" by
myself. The plating spec used was 3-8 u" immersion gold over 100-200
u".
That is the first
time I face such a problem...
Do you
believe that pcb manufacturer has the inspection and
qualification equipement to make sure everything's fine with ENIG plating
?? Is there any pcb supplier on the line willing to answer
?
Unfortunately,
even if some papers has been published up to now about the subject it seems it's
still unclear about what is the real cause of the problem. So I agree with
you about the need of a thorough scientific investigation about that. Also agree
that ENIG must very reliable versatile finish...
Regards,
Mario
Bonjour
Mario,
This is a loaded question. I am not sure that there is a
staright answer to it.
However it would be important to find out how
"Black Pad" has been established as the cause of the defect.
The term
"Balck Pad" althu initailly a very specific one, is now widely attributed to
any soldering or joint reliabilty issues with the ENIG finish. This wide
indiscriminate use, interferes with a thorough scientific investigation that
may expose other important root causes.
How much gold was specified?
The new IPC-4452 ENIG specifications specifies 3 - 5 uins 0.075 to 0.125
microns. It also warns that excessive gold thickness could lead to problems
with the surface of the underlying Nickel.
if properly specified
and reasonably controlled during manufacturing is a very reliable versatile
finish.
George Milad
Chairman IPC Plating Committee
UIC
Tech
Sales Rep
(516) 901-3874 cell
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