Your mileage may vary but for 8 layers with the digital ICs on the bottom, I would do this: 1. Top Motor drive parts 3-4 mil dielectric 2. Power =< 4 mil dielectric 3. Gnd1 4 mil dielectric 4. S1 >10 mil dielectric 5. S2 4 mil dielectric 6. Gnd2 match L2/L3 dielectric =< 4 mils 7. Atmel / SDRAM power 3-4 mil dielectric 8. Bottom Atmel / SDRAM parts For an 0.062" thick board it is easy to make the dielectric between layers 4 and 5 20 mils or thicker. Cross talk will be a non-issue even for tandem lines. Normally I would have put the digital ICs on top, in which case layer 2 swaps with layer 7. I don't know if you've placed the motor junk on top for heat sinking or other reasons. Typically those sorts of things have the through hole connections which would favor flipping and bottom. Steve Jaison Fernandez (RBEI/EED2) wrote: > Dear Experts, > I have a layer stack up like as follows: > > 1. Top > 2. Gnd1 > 3. Power > 4. Gnd2 > 5. Sig1 > 6. Sig2 > 7. Gnd3 > 8. Bottom > > > My board is one which contains ATMEL AT91SAM9M10, 128MB SDRAM (166MHz), GPS > Chip solution, High current motor Drivers etc. > > I placed Atmel and SDRAM in bottom layer and routed the SDRAM signals in Sig1 > and Sig2 planes. > Could any one tell me the chances crosstalk between sig1 and Sig2 planes and > possible ways to avoid it. > Due to some tool limitations I can't able to due any POST SI analysis.(Stack > up of Layer1 to Layer 3 is fixed due to some high current applications) > > Regards, > Jaison Fernandez > ------------------------------------------------------------------ > 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 > > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > > -- Steve Weir IPBLOX, LLC 150 N. Center St. #211 Reno, NV 89501 www.ipblox.com (775) 299-4236 Business (866) 675-4630 Toll-free (707) 780-1951 Fax ------------------------------------------------------------------ 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 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu