Hello All,
We have had some limited success in detecting opens at the first level in
laminate flip chip applications using CSAM.  This was primarily due to the short
path (through the back of the chip) which allowed the use of a relatively high
frequency transducer that gives enough detail to detect the defects.  If the
same transducer is used in a BGA application where the path is longer and
contains more reflective interfaces as Dave mentioned, the signal will most
likely be lost.

One variation that may contain some hope is through transmission acoustic
microscopy, where the signal is passed throught the package rather than
reflected back to the source. I have limited knowledge of this technique, but
have been told that it is applicable to BGA's and has adequate detail.  Any
others heard anything about it?

Regards,
Rod Martens
Hewlett-Packard Co.
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Subject: Re: [TN] Crack detection under BGA?
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