Hi Al/All:
I think that the simple point is that we need both simulation and measurements.
It's possible to screw up one or both of these while pursuing the Holy Grail,
where everything agrees, is perfect, and available immediately. Many on this
list could provide a long list of situations where measurements are
meaningless. (Al: I know that you've put a lot of effort into this ...
including launch de-embedding and many other issues ...)
On the simulation front, the hope is always to get a ready, immediate answer to
something that would almost always take months to build and measure.
Both cost $, so that part's a wash ... Whatever the simulation software, the
goal is to gain insight NOW. If everyone could have immediate, perfectly
accurate results from measurements, sure, but that's not possible, by
definition.
So, we try to make simulation as immediate and accurate as possible and people
like Wild River try to make physical validation an approach that both increases
accuracy and shortens lead time. But we're all chasing the same goal ... It's
not either/or but both.
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
al@xxxxxxxxxxxxxxxxx
Sent: Monday, December 23, 2019 9:23 AM
To: corley@xxxxxxxxx; Lyndell.Asbenson@xxxxxxxxxxx; leeritchey@xxxxxxxxxxxxx
Cc: maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx;
si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Chuck, right on! Lee, really, again? Rating simulation over measurement
slights the concept of a high confidence concerted design flow capable of
achieving 1 spin signal integrity IEEE P370 rated performance to 50GHz.
It reminds me when I was applications engineering TDR/VNA in my early days
and folks asked what is better: VNA or TDR? Is night better than dark,
what is better the Ying or the Yang; they are both parts of a balanced flow.
Stellar signal integrity design teams can usually predict simulation to
measurement within 2-3ohms simulation to measurement impedance profile, how
many fab-measurement cycles do you need to achieve that? That simulation
capability achieves less spins and much higher performance. The part B
if this paradigm is most/all simulation packages have issues with something:
meshing, memory management, loss model/material identification and
benchmarking the tools is really important also.
Having said that we (track chair folks) recently rated the track 12
Test/Measurement DesignCon papers and there are some very good papers on PDN
analysis, jitter analysis, etc. and the quality of the papers this year
looks really good this year. When your management explains "the companies
policy" is that only 1 or 2 folks are selected to attend, and you didn't make
the cut, you should explain "my policy" is that I go every year, whether the
company sponsors it or not, then go!
Ping me to discuss signal integrity, fly fishing, the conference, etc. in the
bar at the DesignCon 2020 convention center during breaks, will be happy
to buy you a beer or beverage. Happy Holidays SI folks!
- Al Neves
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf Of
Chuck Corley
Sent: Sunday, December 22, 2019 9:39 AM
To: Lyndell.Asbenson@xxxxxxxxxxx
Cc: leeritchey@xxxxxxxxxxxxx; maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Nicely said. Still, I'll take a good measurement over a simulationday.
any
That's why we make such elegant measuring equipment.Measurements and simulations go together. You need both. When simulating,
I am amazed at your statement?
Lee,day.
I am amazed at your statement?
-Lyndell Lee Asbenson
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Lee Ritchey
Sent: Friday, December 20, 2019 11:34 AM
To: corley@xxxxxxxxx
Cc: maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Chuck,
Nicely said. Still, I'll take a good measurement over a simulation
any
That's why we make such elegant measuring equipment.VLP copper.
Lee Ritchey
Speeding Edge
P.O. Box 817
Bodega Bay, CA
94923
408-781-0253
I took the energy needed to be mad
And wrote some blues
Count Basie
Worry is like a rocking chair,
It keeps you busy, but doesn't get you anywhere.
Ross Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On
Behalf Of Chuck Corley
Sent: Friday, December 20, 2019 9:45 AM
To: leeritchey@xxxxxxxxxxxxx
Cc: maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Hi Maruthi,
What's the minimum bitrate after which I should start worrying aboutthe surface roughness parameters of the copper used in PCB ?
You were probably hoping for a one-word answer. But instead you might
have heard back many more words than you had wished for.
Here's what I suggest as the best answers to your question in order of
quality:
1. Best quality results: Use a simulator and enter the values as part
of your simulations. This will also allow you to learn how big an
effect this has by modifying your simulation to include or remove the
roughness effects on different runs.
2. Use Lee's list of measurements below as a rough guideline of the
losses you could expect. Not quite as good as actually simulating it
(no offence Lee ;-) but still a good estimate of how much loss you can
expect at the frequencies Lee documented.
3. Lowest quality answer: 10 Gbit/sec. This is probably the simple
one-word answer you were hoping for. This is about the speed where I
start to worry about it. But it also depends on the trace length and
other factors, so this is not an absolute answer. This is more of a
"somewhere around 10 Gbit/sec, but it depends" kind of answer. Not
nearly as high quality of an answer as #1 or #2.
Chuck
Chuck Corley, National Instruments
On 2019-12-19 11:09, Lee Ritchey wrote:
Here is some measured data that you can use to decide whether smoothcopper
is worth the cost.
In 2013 we build a test PCB with a set of trace layers built from
Reverse treat copper ( what you get if you don't specify a finish)
and
are,
The paper was 5-TP5 Titled High Speed Losses in various materials
The test traces were 8" long (20 cm) and 4.5 mils (.11 mm) wide.
At 5 GHz (10 Gb/S) the loss was 0.2 db.
At 14 GHz (28 Gb/S) the loss was 2 db.
When you need to specify smooth copper depends on how good your
serdes
how long the path is and how good the laminate is. Some newer serdesBehalf
toleratet38 db loss at 28 Gb/S. Takes a pretty long path to need
smooth copper with such serces.
Lee Ritchey
Speeding Edge
P.O. Box 817
Bodega Bay, CA
94923
408-781-0253
I took the energy needed to be mad
And wrote some blues
Count Basie
Worry is like a rocking chair,
It keeps you busy, but doesn't get you anywhere.
Ross Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On
Of MARUTHI PRASANNA Cwrote:
Sent: Thursday, December 19, 2019 8:18 AM
To: shlepnev@xxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Thank you Yuryl , I'll go through them .
On Wed, Dec 18, 2019, 8:45 PM Yuriy Shlepnev <shlepnev@xxxxxxxxxxxxx>
Hi Maruthi,
The best way to figure it out is with a numerical experiment.
To start with, pick up a realistic roughness model that correlates
with the measurements - a number of such models for different type of
copper treatments is available in our app notes at
https://www.simberian.com/AppNotes.php Build a model of your link and
see the impact by turning the roughness on and off.
The impact of different signal degradation factors, including
roughness, for different data rates was a subject of the recent SIJ
webinar - see #9 at https://www.simberian.com/Webinars.php
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
www.simberian.com [1] [1 [1]]
Simbeor - Accurate, Productive and Cost-Effective Electromagnetic
Signal Integrity Software to Design Predictable Interconnects!
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
On
Behalf Of MARUTHI PRASANNA C
Sent: Wednesday, December 18, 2019 2:10 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Surface roughness of copper
Hi everyone
What's the minimum bitrate after which I should start worrying about
the surface roughness parameters of the copper used in PCB ?
Does the amount of signal energy in the first harmonics , second
harmonics have any impact on this ?
I appreciate answers on this , thanks in advance .
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
