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May 2002

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Subject:
From:
Henry Rekers <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 16 May 2002 13:34:19 -0700
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This is a tough one.  We have had intermittent problems with a particular
bga (Motorola 357 ball, 50mil pitch)  The defect manifests itself as a "head
in pillow" joint near the corners of the part always on the outside rows.
It's a real nasty one because most of the time it is not detected
electrically until aged and/or shaken.  Sometimes you can physically push on
the part and make the connection.

We've had some Shawdow Moire testing done and the part deflects 6.5mil and
the corners throughout the reflow temperatures (independant of soak time)

The reflow profile is bang on.  I don't suspect the print or paste.

Have you ever delt with a problem like this?  How did you fix it?

Thanks in advance.

Henry J. Rekers
Manufacturing Engineer.

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