Carl: Insufficient reflow of solder connections is more common than most
believe (usually improper thermal profile or loss of process control).  The
condition you describe sounds like that pictured by Figure 12-136 on page
12-81 IPC-A-610C and is a serious defect.  We (put on my consulting hat here)
recently had a client who experienced insufficient reflow on a number of
connections and it sounds like you have an identical condition.  I have some
photo's of microsectioned connections that show solder balls (un-reflowed)
trapped inside the partially reflowed connections.  At the moment I am away
from the office (doing some work at one of our defense contractors sites) and
do not have access to the photos.  I will email .jpg files of microsections
when I get back to the office on Friday evening.  I would be interested in
seeing what your microsections show.
Hope the above helps some, be cautious and go slowly, this is a serious
problem (do NOT disposition the product "use as is" until you get the results
of microsectional analysis).  Regards, Jim Moffitt, Technical Director,
Electronics Training Advantage, Indianapolis IN

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