Hi, generally, the layers should be symmetrical. The details of the layout depend on the details of the board. Stephanie Goedecke Philips - SP3D Chip Design GmbH Petersbrunnerstr.17 82319 Starnberg / Germany Phone: +49-8151-270-160 Fax : +49-8151-270-200 Hi , In 10 Layer Board stack How Multiple Ground Plane Will be More effective and Why. Is there any Formula/Thumb rule behind this. most of my Critical Signal ( CLK) are Running at Signal Layer 1 and My Board Stack up is Top GND Signal Layer 1 VCC3.3 GND VCC2.5 Signal Layer 2 Signal Layer 3 GND Bottom Thanks in Advance. ------------------------------------------------------------------ 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 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