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. * ****************************************************************************