Or for EMI control (thanks to Rick):
1--Signal
2--GND
3--Signal
4--Signal
5--PWR
6--GND
7--Signal
8--Signal
9--GND
10-Signal
or a potential 8-layer stack:
1--Signal
2--GND
3--Signal
4--PWR
5--GND
6--Signal
7--GND
8--Signal
The 8-layer stack worked well with a DSP-design I did a few years ago running at 100-200MHz, but this stack should work fine. Board was very quiet; couldn't say the same for the I/O and power lines, noisy as could be (caps -n- ferrites fixed that). If you don't have enough routing channels/area, swap layers 1-2 and 7-8 if it leaves you with enough ground plane.
Roger
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of Jack
C. Olson
Sent: Thursday, December 09, 2004 1:42 PM
To: [log in to unmask]
Subject: Re: [DC] 8 or 10 layer layout recommendations
Kind of a big question,
and not knowing how much experience you have...
Anyway, I am getting to where I put a lot of the power routing
on the surface layers, and then fill the rest of those layers with
shielding or chassis ground and even the voltage planes that aren't
that good for reference planes, like +5V these days (most of your
critical devices will be the lower voltages, from my experience.)
So that's the outer layers,
then the next two inner layers 2 and 7 will be all the junky routing
for traces that don't matter so much,
then layers 3 and 6 will be my good power/ground planes,
and all the critical routing will be sandwiched between them on
layers 4 and 5, using dual stripline calculations.
Of course, the recent talk on this forum about low speed lines
bouncing back and forth between layers 2 and 7 using who
knows what for reference has shaken the core of my foundation,
so take all that with a grain of salt...
hope that helps,
Jack
(p.s. are you using a lot of differential pairs?)
John Brubacher
<johnb@SILENTWITN
ESS.COM>
Sent by: To
DesignerCouncil To
<DesignerCouncil@ [log in to unmask]
ipc.org> cc
12/09/2004 11:18
AM
Subject
Please respond to [DC] 8 or 10 layer layout
"(Designers recommendations
Council Forum)"
<DesignerCouncil@
IPC.ORG>; Please
respond to
johnb@SILENTWITNE
SS.COM
Caterpillar: Confidential Green Retain Until: 01/08/2005
Retention Category: G90 -
General
Matters/Administration
Has anybody had experience with an 8 or 10 layer pcb with a dsp running at
400 - 600MHz and 2 power planes? I am looking for recommendations for
stackup and routing.
Honeywell Video Systems
John Brubacher, CID
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