Wojciech Babij
NEWBRIDGE
[email protected] on 09/17/97 07:57:53 AM
To: [email protected], [email protected]
cc: (bcc: Wojciech Babij/UB Networks)
Subject: [SI-LIST] : ?? : [SI-LIST] : stackup impedance.
=
Hi,
For S-S-G-P-S-S stackup, to avoid crosstalk, the distance
between first signal layer and second must be much larger than the
distance between second signal layer and power or ground plane(a=
t
least 3 times), which in turn will result in large differences of th=
e
trace's characteristic impedance between first signal layer and secon=
d
, not good for signal. Is there any special reason to arrange the
stackup in such manners? However, for the signal layer that is close=
to the plane, formula for embeded microstrip might still work, for the=
top or bottom layer, it will vary according to the neighboring trace in=
the second and third signal layer accordingly. We have tried such
stackup, lots of troubles.
regards
weber
> -----????-----
> ???: John Lin - TAO [SMTP:[email protected]]
> ????: 1997?9?17? ?? 02:45
> ???: 'SI_LIST'
> ??: [SI-LIST] : stackup impedance.
>
> Hi,
> Does anybody have idea about how to calculate the impedance of
> stackup with following structures.
>
> S-S-G-P-S-S ( 6 layers).
>
> and
>
> G-S-S-S-S-P (6 layers).
>
> I checked books and tried to find equations to calculate impedance.
> However, I cannot find any.
>
>
> Best Regards,
>
> JOHNLIN
> CAE Engineer of EDA Department
> Digital Equipment Corp. Taiwan Branch
> Email: [email protected]
> TEL: 1-886-3-3900000 ext. 2565
>
>
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