It may be worth asking your customer if they changed the direction of their
vibe to a different plane, ie x vs y vs z.  Also, a different way of
applying your loctite could contribute to failures @ heat cycling.  Just my
$0.02.

Bill C.

-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Monday, January 29, 2001 6:08 PM
To: [log in to unmask]
Subject: [TN] CQFP cracking...


Hi all,

We build a board here that's been built here before, using the same
processes. It is  around 8" X 8" polyimide fab, that has two very large
352-pin CQFP's on it. One of the customer requirements is that these parts
be
bonded to the board using Loctite 3615.
So we print paste, then dispense the epoxy, place the parts, and then
cure/reflow the assembly.

With this last build we've done, the customer is reporting that the CQFP's
are cracking during their thermal cycle and vibration tests. This has not
happened before.
Is it possible that we have gotten a suspect batch of parts? Has anybody
else
ever run across this type of problem before?

Thanks!

-Steve Gregory-

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