RE: [SI-LIST] : Plane Splits Inspection

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From: Zabinski, Patrick J. (zabinski.patrick@mayo.edu)
Date: Fri Nov 10 2000 - 08:34:20 PST


Mike,

Short answer: no.

A bit longer answer: The experiments I ran this summer relied on a simple
passive
board to characterize splits and common stitching cap theories. Much of
what we
found followed common theory, while much of what we found was surprising (at
least
to me).

We did consider placing the caps as you mention, but it would have been
difficult to
do in our test environment in that we want to basically "slide" the cap
along the split
to see how the cap location effected performance; much easier than trying to
slide
a via.....

Pat

> My two cents.
>
> Patrick:
>
> Have you tried putting caps not across the split, but from
> the edge of every
> split to the solid plane?
> By putting them across the split you, though eliminating
> discontinuity,
> defeat the effect of split plane (planes are split not just
> for the sake of
> voltage difference but also for noise reduction, like analog/digital,
> hi-speed/digital, etc), introducing the noise from more noisy
> plane to the
> quiet one.
>
> However, putting caps along edges from edges to Solid plane,
> you provide
> almost just as good return path without coupling the noise.
>
>
> Mike.
>
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