Hi Per! I finally found the paper on the bent columns! I think this was
part of an ECTC or IMAPs conference (sorry, I didn't record where I got
it). The paper is titled "Robustness of Deformed Ceramic Column Grid Array
Columns", authors Ellyn Ingalls and Janet Jozwiak of IBM Microelectronics
in Hopewell Junction NY. I have Ingalls email listed as
[log in to unmask] . I interpret their data slightly different than the
authors (I believe they tried to put a more positive conclusion on the
data) - I think the data shows that once a column gets bent, a severe drop
in reliability occurs. Take a look at the paper and let me know what you
think.

Dave




Tegehall Per-Erik <[log in to unmask]>@ipc.org> on 06/04/2002
02:26:34 AM

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Subject:    Re: [TN] Re column grid arrays


Hi David,

What do you mean with bent? The information I have got from IBM is that it
is normal that columns ar tilted due to the fact that fillets will be
assymetric caused by an allignment to the edge of the solder pads. This
sholdn´t affect the reliability. But from your description I get the
impression that there is a bend on the columns. Is that correct? Where has
the IBM paper been published?

Regards
Per-Erik Tegehall
IVF, Sweden

-----Ursprungligt meddelande-----
Från: Dave Hillman [mailto:[log in to unmask]]
Skickat: den 31 maj 2002 22:06
Till: [log in to unmask]
Ämne: [TN] Re column grid arrays


Hi Earl! Hey, did you ever get an feedback on how the CCGA's performed in
their use environment (and what was the use environment conditions)? We
have successfully placed CCGA's in both the semi-automated and automated
assembly modes but if the columns are bent - even slightly - we have seen a
pretty hefty reduction in solder joint fatigue life (avionics use
environment). I have an IBM paper which showed similar results.

Dave Hillman
Rockwell Collins
[log in to unmask]




Earl Moon <[log in to unmask]>@ipc.org> on 05/31/2002 12:34:20 PM

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Subject:    Re: [TN] NTC - The Gregory's are a team now...


Never experienced any problems with CCGA's either in production or
replacement. I did hundreds of these things with the SRT because of an
upgrade. It took almost six months for all the replacements at 24 per board
with 1200 columns. Only minor problem was with sorting out GSM placement
accuracy concerning the vision system.

Really had to watch column alignment though as you say. Other than that, no
problems. I guess, as I don't clearly remember, the force issue was
resolved
as a function of machine programming but the parts were so heavy anyway, I
don't think it mad a difference as they just sunk into the paste and
aligned
very well.

Interesting stuff, eh Gaby?

Earl

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