Henry/Werner,

   I work in a Component/Material Analytical Lab.   I conduct cross section
of all interconnection.   I have found interconnection failures in BGA,  the
failure will be:  Fracture in the bulb solder, IMC region or nickel plating.
The problem with subsequence rework is did the PWB reach a reflow temp.
environment which can re-grow the IMC region.  potential for a weak joint.
We can take this off line if so desired.

victor,

-----Original Message-----
From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: Wednesday, June 19, 2002 7:48 AM
To: [log in to unmask]
Subject: Re: [TN] Intermetallic Joint Failure


Hi Henry,
The problem with "rework" is not IMC layers getting too thick, but the
damage
done to the solder joints of neighboring components and the PWB. In all my
years in reliability, I have never seen an "Intermetallic Joint Failure."

Best regards,
Werner Engelmaier

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