I'll let Scott or others comment on the 12% ...
Reiterating what Scott said, signals "see" Dk(z), while some laminate vendors
publish Dk(xy) using IPC TM-650 2.5.5.13. I've made it one of my life goals to
kill usage of that test method. It has close to zero relevance in SI
simulation.
I've authored or coauthored a couple of articles on this, with the help of Don
DeGroot (CCN):
https://www.signalintegrityjournal.com/articles/1337-apples-to-apples-material-characterization-for-high-speed-pcb-design
(Scroll down to "E-Field Orientation.")
https://pcdandf.com/pcdesign/index.php/current-issue/266-material-matters/13446-material-matters-1903
(They gave this column a weird title ... but it includes a nice picture of why
Dk(z) and Dk(xy) are different.)
Bill Hargin
Director of Everything
Z-zero ▪ Innovative PCB Stackup Design ▪ www.z-zero.com
billh@xxxxxxxxxx ▪ 425-301-4425 ▪ Skype: bill.hargin
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf Of
Jason Ellison
Sent: Friday, December 13, 2019 10:50 AM
To: Scott McMorrow <Scott@xxxxxxxxxxxxx>
Cc: si-list <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: [EXTERNAL]PCB Isotropy
Hi Scott,
To be clear, you're suggesting to reduce the DK by 12% in the z-axis?
Thanks!
Jason
On Fri, Dec 13, 2019, 1:32 PM Scott McMorrow <Scott@xxxxxxxxxxxxx> wrote:
Yes. IF the pcb plane is x/y then the anisotropic behavior of Dk is
about 12% higher. This can be modeled in HFSS with tensor dielectrics.
Scott McMorrow, CTO Signal Integrity Group Samtec Office 401-284-1827
| +1-800-726-8329 www.samtec.com
* Scott McMorrow*,
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On
Behalf Of Jason Ellison
Sent: Friday, December 13, 2019 1:19 PM
To: si-list <si-list@xxxxxxxxxxxxx>
Subject: [EXTERNAL][SI-LIST] PCB Isotropy
Hello SI Community!
Does anyone know of a PCB laminate permittivity isotropy study?
Specifically, I'd like to know if the permittivity is different when
the signal is propagating through the board vias (Z-direction) vs
along traces within the board (X-Y direction).
Cheers,
Jason
Employed by and affiliated with Amphenol AICC (
https://www.amphenol-icc.com/
)
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