How to route a four layer PCB

Former Member over 9 years ago

Hello, I want to route a 4 layer PCB with one of them dedicated to GND.

My problem is the following:

I can do a dedicated layer for GND but, the Autorouter do not link with this layer for GND....

Have you got any solution?

Or tutorial for multi-layer routing please?

Ps: I am on Eagle

Version 7.1.0 for Windows

Standard Edition

0 sauerwald over 9 years ago

What I would do would be to place a polygon, assigned to GND on the layer which you want to dedicate to GND. Depending on how firmly you want that layer dedicated, you can set the autorouter parameters to avoid routing on that layer altogether, or just place a high cost on traces routed on that layer.
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0 engswee over 9 years ago

Dear Jean,

Are you sure you want to run autoroute on a 4 layer PCB design?
Do you have plan or setting for your autorouting?
Yea I also recommend you using palygon at that layer and name it GND then all your GND will connected to it. I assume you know the process like polygon set to cover all the PCB, change the name and ratsnest to see the connection.

Some example:
http://www.build-electronic-circuits.com/eagle-ground-plane/
EAGLE Tutorial: Ground Planes with Polygons - YouTube

cheer
ES
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0 Former Member over 9 years ago

Thank you for your answer!

I have no problem for using polygon. I have done it on the 3rd layer (I use layer 1, 2, 3 and 16. with buried and trough via).

But, the autorouteur do not put Via automatically to this Ground Layer.
I mean I have lot of SMD on the Top layer and I would like to connect them automatically to my Ground layer by Via but it do not work.
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0 autodeskguest over 9 years ago in reply to Former Member

On 31/10/14 09:21, Jean-Romain Durand wrote:

I have no problem for using polygon. I have done it on the 3rd layer (I
use layer 1, 2, 3 and 16. with buried and trough via).

But, the autorouteur do not put Via automatically to this Ground Layer.
I mean I have lot of SMD on the Top layer and I would like to connect
them automatically to my Ground layer by Via but it do not work.

I don't use the autorouter (frankly, all autorouters do a much worse job
than I can) but from what I understand, you will need to do this in two
steps:

- First, set the autorouter rules to really like vias and REALLY like
layer 3. Then route only the ground signal
- Next, set the rules to avoid layer 3 entirely and route the rest of
the signals that way
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