Here is some measured data that you can use to decide whether smooth copper
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 VLP copper.
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 are,
how long the path is and how good the laminate is. Some newer serdes
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 Behalf
Of MARUTHI PRASANNA C
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> wrote:
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
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