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Route a 4-layers with ground and power planes

Message 1 of 5
652 Views, 4 Replies

Route a 4-layers with ground and power planes

Hello everyone,


I've read anything I could on the forum and in the documentation and cannot figure out how to do a simple routing with 4 layers. What I am trying to create is a simple 4 layers PCB with Signals on top and Bottom, and 2 additional layers in the middle with GND and Power.


So far I have a 2 layers design that I am trying to transform.


What I have done and tried so far is:

- add the 2 new layers in DRC with the capabilities of the manufacturer.

- create a GND polygon on the ground layer (layer 2). All ground nets are named GND.

- create +24V polygones and +5V in different places on the Power layer (they also are named the same way in schematics)


Autorouting routes everything on top and bottom only.


I tried "Auto GND" command to try to route only the GND nets on Ground layer. If I only select the ground layers it complains that SMD pads are not reachable. If I add the Top layer and gives via a cost of 0, ground a cost of 0 and top layer a cost of 99, it routes everything on top layer as well.


I am not sure to understand how fanout works in Fusion 360 but anything I did with it created a via from top to bottom when selecting a ground net.


What I am trying is to leverage the autorouting to start with and edit manually after.

Is there some documentation on how to route signals on specific layers, and on a specific one and power on another? 


Auto ! GND would route all but GND but then I have to create all the vias for all GND pads? It sounds like Fusion should do it for me.


Power, Signal and GND nets are in 3 different classes if that can help.


What am I missing? Any help or pointer in the right direction would be appreciated!


Message 2 of 5
in reply to: remiBB5EP

Did you enable the extra 2 layers under the DRC>Layers dialog box (edit: I see now you did), and change those layers from N/A to Auto in the autorouter dialog box? There isn't an easy way to do what you're trying to do, but pouring the ground polygon on the ground layer, routing only the ground net with only the ground and outer layers enabled 

should get you close.

Message 3 of 5
in reply to: remiBB5EP

Edit: ok, got fanout working when set in Signal type. Using Device type, it does not connect to the ground plane automatically. So I guess I can fanout ground and power pads and then route normally on the other planes.


Is that the way I should do?


Message 4 of 5
in reply to: usoldering

OK, so I got the fanout (device and signal) working properly after uninstalling and reinstalling Fusion. Some weird things happened (like the data panel disappearing and many crashes when saving) so I thought it would not hurt to try reinstalling.


Since then, I just re-opened the board file and it works as it should. Not sure what was the problem.

Message 5 of 5
in reply to: remiBB5EP

Unfortunately, while fanout works now, crashes continues to happen on saving. Here is the last report: 318444561

Do you see anything in it to help solving this recurrent crash issues? 


Thank you very much,


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