To Barry and others,

I personally find the Veribest web calculator site a bit confusing and limited.
What if I have a 10 layer using buried microstrip and stripline (not dual or
"balanced" as you like to say) and using 50 ohms and 75 ohms on the same layer?
A better web site is at www.automata.com/tools. Yours is ok maybe for your own
organization, and for others, IF it's verified by whomever will sign up to fab
the board. I would never make and impedance assumption without verifying my
values with what my fab house will be working to. 

Good first cut though. I hope you have time to continue on with this site.

Mitch Morey
Sr. PCB Designer
TRW, Inc.
Redondo Beach, CA 90278
Phone: (310)814-5765
Fax:   (310)812-4949
EMAIL: [log in to unmask]

                               |||||
                              ((o o))
____________________________oOO_(_)_OOo_____________________________

     PCB layout is like fine art. You have to DIE to be famous!
____________________________________________________________________
                             (_)   (_)

> If you would like to calculate the impedance of a particular board 
> stack-up check out our Interactive Impedance Calculation on the 
> In-Circuit Design web site: http://www.icd.com.au
> 
> The main variation will be with the dielectric constant of FR4 wich 
> may vary from 4.2 to 5.2 but you can specify an exact value to the 
> board manufacturer it required.
> 
> The Impedance calculator is based on formulae from the IPC-D-317 and 
> allows you to alter trace width, dielectric constant, Pre-preg 
> thickness and Cu thickness in order to select the desired impedance.
> 
> Cheers,
> 
> Barry
> ___________________________________________________
> 
> Barry Olney		      http://www.icd.com.au
> Managing Director			

****************************************************************************
* The mail list is provided as a service by IPC using SmartList v3.05      *
**************************************************************************** 
* To unsubscribe from this list at any time, send a message to:            *
* [log in to unmask] with <subject: unsubscribe> and no text. *
****************************************************************************