Hi Experts, We calculate the track width for the required impedence with reference to the immediate adjacent plane layer. Some people argue that, we can take the plane layer as reference even if it is not the immediate next layer. For example, Layer 1 --- Layer 2 --- Plane Layer 3 --- Signal Layer 4 --- Signal Layer 5 --- Signal Layer 6 --- Plane Layer 7 --- Layer 8 --- In the above stackup, can the Layer 4 signals take either Layer 2 or Layer 6 as reference for impedance calculation? The height between the signal and plane layers, -- can we take the height between Layer 4 and Layer 2 or 6? Please reply. regards Sumathi Love Cricket? Check out live scores, photos, video highlights and more. Click here http://cricket.yahoo.com ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu