RE: [SI-LIST] : BGA Pkg Characterization

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From: Dagostino, Tom (tom_dagostino@mentorg.com)
Date: Mon May 21 2001 - 09:27:53 PDT


I've heard of PC133 designs that were sensitive to the package used by the
memory vendor. It is likely the edge rate rules, not the clock frequency.

Tom Dagostino
Modeling Manager
Mentor Graphics Corp.
SAE
tom_dagostino@mentor.com
503-685-1613

-----Original Message-----
From: Larry Miller [mailto:ldmiller@rhapsodynetworks.com]
Sent: Monday, May 21, 2001 6:49 AM
To: 'Neeraj Pendse'; Larry Miller
Cc: SI_LIST (E-mail)
Subject: RE: [SI-LIST] : BGA Pkg Characterization

Nope. The response characteristics depend upon how the routing from chip to
ball is done, and that would be a monstrous problem for a mathematical
analysis. It would also vary with manufacturer, unless they were all using a
particular package scheme.

The data I have seen is measured and curve-fitted with equivalent R-L-C
multi-section filters. There are trace-to-trace C's and mutual inductances
(transformers) and the resulting networks are definitely non-planar! Quite a
chore.

Some of these testing facilities that have responded here can give you
response sweeps (VNA runs) or TDR plots. I do not know if they offer the
services to turn these into SPICE models, for example. If you are working
below 300 MHz you probably wouldn't care. But 500 MHz to 2+ GHz is
definitely into the region where BGA parasitics ring loud and long.

Larry Miller

-----Original Message-----
From: Neeraj Pendse [mailto:cnepsc@ptg.nsc.com]
Sent: Friday, May 18, 2001 11:43 AM
To: Larry Miller
Cc: SI_LIST (E-mail)
Subject: RE: [SI-LIST] : BGA Pkg Characterization

Larry and anyone,

Have you found a way to predict resonance in BGA packages based on the
frequency, package size and substrate stack-up? And do you have any
advice on when I should be concerned about dying because of package
resonance?

Regards,

Neeraj.

National Semiconductor Corp.
http://www.national.com NYSE: NSM

>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 5/18/01, 6:22:48 AM, Larry Miller <ldmiller@rhapsodynetworks.com>
wrote regarding RE: [SI-LIST] : BGA Pkg Characterization:

> You really do need to do this if you are contemplating usage up above
300
> MHz. Many packages have simply awful resonances and crosstalk, and it
varies
> hugely with where you are on the package. I have found 4:1 variations
in
> lowest resonance frequencies in a single package due to the variations
in
> the way the signals get from the chip bonding pads to the balls. Also,
you
> need to test groups of signals. Various sets can resonate in pairs,
etc.

> Good luck!

> Larry Miller

> -----Original Message-----
> From: Wesley Wu [mailto:wesley@redswitch.com]
> Sent: Tuesday, May 15, 2001 8:23 PM
> To: SI_LIST (E-mail)
> Subject: [SI-LIST] : BGA Pkg Characterization

> Hi All,

> Has anybody done characterization on existing BGA packages recently? I
need
> to
> know if there is anyone who can do this for me and what is the
estimated
> cost. The
> required measurements include characteristic impedance along traces,
delay
> and
> gain on both directions of traces across the frequency band of 500M -
2GHz,
> ground
> bounce, cross talking, and ringing. I would like to obtain a data
range for
> all
> these to see if some particular BGA packages are suitable for my
> applications.
> Ideally I would like to add some equivalent to bond wire and IC input
> capacitance
> during test. Your help is greatly appreciated.

> Wesley Wu
> RedSwitch, Inc.
> (408)719-4748

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