NOPE9 YES wrote:
> I may have to layout a PCB with 10 layers , 3 users , 30 pages of schemat=
ics.  From what I have learned from the PIClist, I would favour Eagle.  Doe=
s anyone have other suggestions ?  Cost of the tool is a consideration.  Bu=
t not if the tool wastes developer time.
>  =20
I think you also need to seriously consider if you are competant to be=20
doing this work. I'm guessing from your post that you have either done=20
no PCB routing before or only done low speed two layer work before.

High layer counts are expensive so people don't use them without a good=20
reason, most likely high speed signals. But more layers doesn't=20
magically make high speed signals work properly, you have to understand=20
what you are doing and why. You need to think about return current paths=20
high frequency return currents want to closely follow the corresponding=20
signal paths and if you don't want massive EMI you need to let them do=20
so. That means when a signal transfers from a track near one plane to a=20
track near a different plane you need to provide a corresponding path=20
for the return current to transition between the planes (via a capacitor=20
if the planes are at different voltages). You need to manage lots of=20
tradeoffs, understand which signals are most important and so-on.

I'd want to get some experiance doing high speed designs on smallish 4-6=20
layer boards before I even considered a 10 layer monster.
--=20
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