Peter,

   You mentioned that you experience intermittent BGA failures.   How were
these failures confirmed and were they isolated to a specific BGA.   If so,
a cross section would reveal several artifacts as to the nature of the
intermittent condition.   I too have witness suspect nonwet conditions which
was also confirmed by a BGA  peel/shear test.   Finally sem/edx work
condicuted.   Several CAUSES for intermitten can be found.  Any real
destructive photos you can share with me on/off line.   Be happy to share
with you my two cents worth.

victor,

-----Original Message-----
From: Rick Thompson [mailto:[log in to unmask]]
Sent: Wednesday, September 18, 2002 9:23 AM
To: [log in to unmask]
Subject: Re: [TN] BGA failure and Rework


Peter,

There was a discussion of this in regards to a particular vendor on Technet
about 2 years ago.  You can probably find something in the Technet archives
on it.

Rick Thompson

Sr. SMT Process Engineer
SMTEK International, Inc.
+1 (805) 532-2800
[log in to unmask]


===== Original Message from [log in to unmask] (TechNet E-Mail Forum.) at
9/17/02 5:23 pm
>Technet,
>
>If I may continue my question on BGA rework process:
>
>Recently we have seen intermitted failures from a few BGA assemblies.
>After removing the suspicious BGA on the rework station we noticed
>dewetting on a majority number of pads of the removed BGA. The solder
>ball residues were mostly attaching to the board.
>
>Has anyone seen this before? How likely can this be caused by a
>non-optimum rework removal profile Is baking of the board normal prior
>to rework (removal/re-placement)?
>
>We are tackling this issue from the part supplier side and looking at
>performing destructive X-ray analysis. Can someone give me an idea of
>what the ball attachment process is on the BGA?
>
>Rgds,
>Peter
>
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