Here are a couple of links to papers that may be useful for you..... http://www.speedingedge.com/docs/tutorial.doc http://www.amp.com/products/simulation/files/papers/dc99cmdh.pdf Best Regards, Michael C. Greim Sonus Networks mgreim@xxxxxxxxxxxx 978-589-8336 Making the world safe for digital signals everywhere And all this science I don't understand It's just my job six days a week The time is gone. The email's over Thought I'd something more to say...... -----Original Message----- From: Martyn Gaudion [mailto:martyn.gaudion@xxxxxxxxxxxxxxxxxxxx] Sent: Tuesday, July 10, 2001 4:57 PM To: si-list@xxxxxxxxxxxxx Cc: Rich Peyton Subject: [SI-LIST] Re: FR4 Rich, Its well worth taking a look at the laminate vendors web sites. It is also worth noting that FR4 is a resin glass composite based on Glass with Er of around 6 and resin with Er of around 3. If you are designing differential traces on fine spacings you need to take this into account. Typically most fabricators use 4.3 or 4.2 for single ended designs, but for close spaced differential traces they use 3.6 to 3.8 An explanation of this effect is here: www.polarinstruments.com/support/cits/AP139.html Kind regards Martyn Gaudion At 13:57 10/07/01 -0400, you wrote: >Hi > >what is the dielectric constant for FR4? Or a web site with listing of >typical materials and there constants? > >Thanks, >Rich > >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List archives are viewable at: //www.freelists.org/archives/si-list >Old list archives are viewable at: http://www.qsl.net/wb6tpu > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list Old list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list Old list archives are viewable at: http://www.qsl.net/wb6tpu