Pete,

Chances are your manufacturing is right. Multiple heating cycles do not
increase or induce black pads. You might be getting bad boards from your
board shop. It is possible nickel layers were oxidized before
electroless immersion gold process by your board shop, or gold layer
could be too thin or non-existent.

I might have some images of black pad phenomenon. Let me know. I can dig
thru. If I find some, I can email you off-line.

Regards
Matthew P.


-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Pete Houwen
Sent: Friday, October 27, 2006 4:38 PM
To: [log in to unmask]
Subject: [LF] need some SEM/EDX BGA images

I'm  trying to interpret a report we had done on some BGA failures, and
I
need some comparative images.

I've got one image of a partial joint crack.  I've got a number of
images
of dark line defects.  I'm having some difficulty determining if the
dark
lines are actually defects.  I want to find some EDX images that I can
compare to those in my report.  I think the ones I have are showing
proper
concentrations of Phosphorous and Nickel, including Nickel in the solder
balls.  Manufacturing is insisting they are getting bad boards, removing
BGAs and finding black pads all over.  Since there seems to bea  good
amount of Nickel still present, I tend to believe they are creating
black
pads with their thermal profile or multiple heating cycles.

Does anyone know a website where I can find some of these images?

TIA.

Pete

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