WRT has been cross sectioning every high speed platform and see plating and
etch variation is also part of the set of variables, aside from z-axis
anisotropic behavior. The plating variation has been an issue especially
with multi-lamination fabrications. We have also seen incredibly good SI
and consistent Dk for our last 70GHz platform (based on careful TDR) for
micro-vias using 2 plies spread X-Y.
Also recall the Samtec SI team has done some good work modeling these issues
using HFSS.
Your asking a timely question. Fabrication and materials is definitely
our most significant mine in the mine field of stellar SI.
- Al
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf
Of Jason Ellison
Sent: Friday, December 13, 2019 10:19 AM
To: si-list <si-list@xxxxxxxxxxxxx>
Subject: [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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