Re: [SI-LIST] : Modeling Package parasitics

Chee Yee Chung (
Mon, 16 Feb 98 15:37:00 PST

Text item:

formula for inductance of a round wire, isolated in space (assuming no
L = 0.002*length*(ln(2*length/radius)-0.75)

L = uH
Lenght, radius = cm


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Subject: [SI-LIST] : Modeling Package parasitics
Author: owner-si-list@silab.Eng.Sun.COM at SMTPGATE
Date: 2/16/98 2:43 PM

Does anybody have an accurate way of modeling package parasitics,
in particular in a QUAD simulation environment. I have been using
a lumped inductance for a BGA & SQFP package but find this to be very
inaccurate with fast edge rates and small voltage level swings. The ringing
from the inductor causes the signal to cross switching thresholds in the
simulation environment, but this ringing is not seen on the lab bench.
My feeling is that a specified ZO, TPD & and Length should be used
for the bonding wire, trace on the BGA package and the pin.
Does anybody have any thoughts on what values I could use for
the bonding wire?

Mark Nass

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Subject: [SI-LIST] : Modeling Package parasitics
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