Hi Bill, I find the Polar SB200 with the linked SI8000 (I think they call this SB8000) does this very well. The materials library function allows you to capture what each fabricator has for finished press thicknesses, and the "Stack-up Wizard" allows very fast creation of stackups which can then be linked to the impedance calculations. Other features I like is the capacitance and inductance calculations, and the ability to use an Excel spreadsheet to do Monte Carlo Simulations of impedances "As-Built" from a producer and to calculate cross-talk. The resulting .SCI file can be viewed by customers with a free viewer. This way they can see the materials, the DRC, and the impedance calculations. Many OEMs are using the screens from the free viewer of SB200 to document the impedances in their BluePrints. A report on this software is available from the CircuiTree web site, from the Feb, 2005 edition. Happy Holden Westwood Associates "Brooks,Bill" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 01/27/2006 06:25 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Brooks,Bill" <[log in to unmask]> To [log in to unmask] cc Subject [TN] Impedance/ Diff pairs/ layer stack up calculator? We want to evaluate the usefulness of a software tool for calculating differential pairs, and estimating stack up requirements for multi layer boards... Primarily to estimate the correct line width and spacing required in any given design stack up or material combination. Can any of you recommend a tool to do this sort of job that you find useful? I'd like to look at low, med and high end tools and characterize them based on price vs. performance and/or capabilities. Best regards, Bill Brooks - KG6VVP PCB Design Engineer, C.I.D.+, C.I.I. 3030 Enterprise Court, Vista, CA 92083 http://www.dtwc.com <http://www.dtwc.com> Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[log in to unmask] _______________________________________ Member of the San Diego Chapter of the IPC Designers Council Communications Officer, Web Manager http://dcchapters.ipc.org/SanDiego/ <http://dcchapters.ipc.org/SanDiego/> http://pcbwizards.com <http://pcbwizards.com> --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------