Thanks, Robert.
That's really a very creative idea though I am holding some concerns about
it. I will evaluate this structure when getting time. If you have some
paper recommended to read that would be great.
Best,
Tramp
On Thu, Jul 11, 2019 at 6:37 AM Hsiuan-ju Hsu <hsiuanju@xxxxxxxxxxx> wrote:
Hi Tramp,
Would you consider to use coaxial via instead of stitching via?
For stripline (4.5mils),you may drill a large via (dia 26 mils) between
signal layers and plating as signal via, then plug in resin (Dk=3),then
drill a small via (dia 4.5mils) in the center,
then plating the small via as gnd via. You will get good via impedance
control and current return path for your design.
Hope this help..
Robert
åå¾ iOS ç Outlook <https://aka.ms/o0ukef>
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*å¯ä»¶è :* si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx>
代表
Tramp <farhilltramper@xxxxxxxxx>
*å¯ä»¶æ¥æ:* Thursday, July 11, 2019 11:28:26 AM
*æ¶ä»¶è :* shlepnev@xxxxxxxxxxxxx
*å¯æ¬:* Scott McMorrow; Chris.Cotton@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
*主æ¨:* [SI-LIST] Re: [EXTERNAL] The gap b/w stitching vias and tline in
serpentine routing
Thanks for the replies. With the simulated result I currently set the
minimum distance b/w the trace and the guiding stitching via to 3h. Will
collect more data in future projects.
Cheers,
Tramp
On Wed, Jul 3, 2019 at 10:06 PM Yuriy Shlepnev <shlepnev@xxxxxxxxxxxxx>
wrote:
Hi Tramp,vias
The cases with the "reduced" spacing will definitely require the
simulation,
to evaluate the effect. There are no "best gap" approach. Though, the
effect can be quantified for a particular stackup structure and drillproximity,
diameter and it may be not substantial. Note that with the vias
the quasi-TEM mode in the strip trace becomes substantially non-TEM (seefull
demo #2019_03 at http://www.simberian.com/ScreenCasts.php). The best way
to
simulate the effect is the periodic structure analysis approach with a
wave 3D solver. Such analysis extracts modal and per unit length RLGClines
parameters of a periodic structure.
The distance between the stitching vias defines the single-mode (useful)
bandwidth of interconnect. For instance, to have a single mode operation
for
a fenced strip at 30 GHz, the distance between the stitching via barrels
should be less than 2.5 mm (half wavelength), assuming Dk=4. See what
happens above that frequency in demo-video #2018_01 at
http://www.simberian.com/ScreenCasts.php
Also, manufacturing tolerances should be considered when selecting the
minimal distance.
A good introduction into use of stitching vias for strip and coplanar
can be found in E. Holzman, Essentials of RF and Microwave Grounding.Finalist
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
2629 Townsgate Rd., Suite #235, Westlake Village, CA 91361, USA
Office +1-702-876-2882; Fax +1-702-482-7903
Cell +1-206-409-2368; Virtual +1-408-627-7706
Skype: shlepnev
www.simberian.com
Simbeor - Accurate, Productive and Cost-Effective Electromagnetic Signal
Integrity Software to Design Predictable Interconnects!
2010 and 2011 DesignVision Award Winner, 2015 Best In Design&Test
<si-list-bounce@xxxxxxxxxxxxx>]
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx
Onserpentine
Behalf Of Tramp
Sent: Wednesday, July 3, 2019 1:00 PM
To: Scott McMorrow
Cc: Chris.Cotton@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: [EXTERNAL] The gap b/w stitching vias and tline in
serpentine routing
Thanks guys. My intent is to know about the following rules:
When we have to reduce the spacing b/w the parallel segments of
routing, say from the safe 4h spacing (thanks Scott) down to 3h even 2h,we
may need to add stitching vias along the serpentine traces. Now we gettwo
questions:wrote:
a. When adding the stitching vias, what gap would be best? Here gap means
the distance b/w trace and the ground via.
b. What's the smallest spacing that can achieve similar level of
performance as the 4h spacing, by adding stitching vias?
Sounds some useful questions, arent they?
On Wed, Jul 3, 2019 at 8:25 PM Scott McMorrow <Scott@xxxxxxxxxxxxx>
edge
To be clear
1) take the maximum single dielectric thickness on either the top or
bottom of the stripline.
2) Multiply that distance by 4
3) This is the minimum clearance required from trace edge to via pad
in(even if you use non-essential pad removal)
At this distance, the via is essentially invisible to the signal trace.
One member of the Samtec team went through this exercise just this past
month in order to establish our PCB test board design rules.
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 <si-list-bounce@xxxxxxxxxxxxx> On
Behalf Of Scott McMorrow
Sent: Wednesday, July 3, 2019 2:21 PM
To: Chris.Cotton@xxxxxxxxxxx; farhilltramper@xxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: [EXTERNAL] The gap b/w stitching vias and tline
inserpentine routingThis
For symmetric stripline a clearance of 4 times the thickness of the
dielectric from trace to plane works from trace edge to via pad edge.
has been verified through EM modeling with HFSS to 70 GHz
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 <si-list-bounce@xxxxxxxxxxxxx> On
Behalf Of Cotton, Chris
Sent: Wednesday, July 3, 2019 2:08 PM
To: farhilltramper@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: [EXTERNAL] The gap b/w stitching vias and tline
missingserpentine routing
Hi Tramp,
I think it is difficult to answer your question as there are many
adetails such as frequency of interest, spacing relative to dielectric
height, etc. Also, what kind of SNR are you trying to achieve? Is this
ifdigital or analog/RF application. Generally for digital applications,
recognizeyou have the luxury of sufficient spacing to aggressors then forget theGND
vias and the spacing will suffice.
Best regards,
Chris
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On
Behalf Of Tramp
Sent: Wednesday, July 3, 2019 7:36 AM
To: si-list@xxxxxxxxxxxxx
Subject: [EXTERNAL] [SI-LIST] The gap b/w stitching vias and tline in
serpentine routing
[EXTERNAL SENDER: This email originated from outside of Stratus
Technologies. Do not click links or open attachments unless you
distancethe sender and know the content is safe.]the
Dear SIlisters,
I did some quick sims sweeping different gaps b/w the stitching ground
vias and tline (Note here the gap refers to the spacing b/w the via and
tline, not two adjacent ground vias for which I set to twentith lambda)this
using 2.5D tool and the results are almost the same. Does anyone have
experience, such as whether I need to do the sim in 3D, or what
iswith
recommended? I saw some implementations put the via at the distance ofimpact?
merely 4mil while the others do it w/ 20mil. So how on earth is the
--
Best Regards,
Tramp
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