[PCB_FORUM] Re: Impedance controlled line widths

Thanks Ron and everyone else that replied. We'll check out the various
calculator supplied and also read Ron's paper, but for now we're moving
forward again!

 

From: ron.dallas@xxxxxxxxxxxx [mailto:ron.dallas@xxxxxxxxxxxx] 
Sent: Wednesday, August 29, 2007 10:35 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Cc: Jean Bratton
Subject: Re: [PCB_FORUM] Impedance controlled line widths

 


Jean, 

Yes, I believe there is a parameter you can set to suppress the use of
Impedance as a control.   

Our DFM group uses the Polar impedance calculator to define cross
sections.   

I found a wide difference between Polar and Allegro until I got the
dielectric constant and other settings in the Allegro impedance
calculator configured properly. The primary problem is the dielectric on
the conductor. Although it seems wrong, this is used for the dielectric
of the pre-preg that flows around the copper.  It defaults to "air"
which is wrong. 

I wrote a paper on this for CDN Live 2006.  It is on the web at
http://www.cdnusers.org/Portals/0/cdnlive/na2006/PNP/PNP_147/147_paper.p
df.  If you can't get to it, let me know and I'll send you a copy. 

After setting up Allegro as suggested in the paper, I got excellent
correlation between the Polar calculations and Allegro.   
---------------------------
Ron Dallas
Design Technology Group, Teradyne, Inc.
ph: 978-370-2585 
e-mail: ron.dallas@xxxxxxxxxxxx

Other related posts: