Dear Ilan,
The term "shadow vias" is a term that we (Amphenol-TCS) use to describe the
small drill PTH vias we recommend in the vicinity of a differential pin
pair to optimize common and differential transmission.
I will send our work on this topic to your corporate email address.
Regards,
Boris.
On Mon, Jan 30, 2017 at 6:34 PM, Scott McMorrow <Scott@xxxxxxxxxxxxx> wrote:
I'm not aware of any articles specifically about "shadow vias", but I've
not looked, since I've been designing low crosstalk PCB transitions for
many, many, many years. I object to the term "shadow vias", because it is
based on a faulty assumption, that the pin configuration of the connector
dictates the via transition geometry on the PCB.
Rather than looking for papers about shadow vias, I would look for good
papers on PCB via design and localization. Yuriy Shlepnev of Simberian,
has written quite a few good papers on this subject, and providse the
computational electromagnetics field visualizations to help provide some
intuition. Here is a paper from a few years back that might also provide
some insite.
http://www.electrical-integrity.com/Paper_download_
files/DC11_8-TA3_Miller-paper.pdf
http://www.electrical-integrity.com/Paper_download_
files/DC11_8-TA3_Miller-slides.pdf
Scott McMorrow, CTO Signal Integrity Group
Samtec
Office 401-284-1827 | +1-800-726-8329
www.samtec.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Ilan Wolff
Sent: Monday, January 30, 2017 11:16 AM
To: Si-list <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Article showing the advantage of shadow vias
Dear SI-listers,
I'm looking for an article comparing either BGA or connector break-outs
with and without return path shadow vias.
In this case I define a shadow via as a return path via that "accompanies"
the diff. pair only in the PCB but does not have a BGA or connector pin on
top of the via.
Is anyone aware of any comparison work done/presented regarding this item?
Many thanks,
Ilan
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