Hello Obrien,

I concur with George below.  I also have run into major
reliability issues with BGA type chips.  In fact, I once worked
on a portable consumer product that had two C5's on the
main board.  After many attempts to remedy these issues, I
was left with no other alternative but to call for a redesign of
the PCB to change from these BGA type chips to QFP's. 
The change brought tremendous improvements to the
reliability of the product.

Although BGA's may be a design engineer's dream in terms
of saving real estate on the board, I have found that they are
less than desirable in the real world.  The variables alone
involved from manufacturing these chips to processing them
on an SMT line can be a real source of heartache for any
process engineer.  This is especially true if root cause
analysis is needed for any defects found either on the line or
in the field.

Unless your specific application will be for a mild environment
(such as a desktop computer), I suggest that you investigate
this proposed switch to BGA's very carefully.

Regards,

Michael Campos
Process Engineer
MC Assembly & Test
Melbourne, FL
[log in to unmask]

----------------------------------------------------------------------------------------
Obrien,

	I have not run a qualification program for BGA's.  As
such, I  am only watching from the sidelines, however, I have
gleaned the  following information off the technet and other
articles in our  library.

It is my opinion that BGAs are good for applications with
temperature  ranges of 30deg C and less, 50 deg C being the
limit.  Applications  basically are room temperature / air
conditioned applications.  I think  Compaq Computer is still
the bigest user of BGA's.

Another big consideration is vibration.  Happy Holden of
HP-Loveland, or  Fort Collins CO, expressed frustrations with
BGA's in (Inkjet?) printer  applications in a posting last year. 
Too much vibration caused failure  rates to exceed HP's
targeted reliability.  (I was so impressed that a  consumer
electronics firm did reliability studies, that I went out and 
bought an HP Ink Jet.)

It has been my observation that most reliability studies of
BGA's  confine their use to very beniegn environments, and
report excessive  failures in other environments.  There are
many different configurations  commonly refered to as BGA's
which have different reliability levels.   BGA package
suppliers are not all the same.  Variables, Variables, 
Variables.  It seems to me that reliability studies usually
bring bad  news.  Again, these are my observations from the
side lines.  Success  stories may be suppressed as
'company sensitive' information.  Good  luck.  I would be
interested in following your progress.

Finally, there is a JPL study in progress for NASA to
determine the if  BGA's can be used for NASA-type
applications.  Check this for an idea of  how they set up their
experiment:
http://arioch.gsfc.nasa.gov/eee_links/vol_01/no_03/eee1-3h.html
(I hope I typed it in correctly)

-- 

George Franck Jr
Raytheon E-Systems
Falls Church Va.
"The opinions expressed are those of the author, and are not
necessarily those of the Raytheon Corporation."

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