Hello everybody,
Problem description: I have a 4 layer + 2 power plane mixed-signal PCB with SMD components on one side and I would like to route the digital signals on Mid Layer
1+2 and the quiet analogue signals on the Top and Bottom Layers.Altium version: Altium Designer 6.7
Layer Stackup Buildup (no blind and buried vias) Top Layer GND Plane Mid Layer 1 Mid Layer 2 Power Plane Bottom Layer
I placed the digital signals in a 'Digital' Net Class to be able to assign a routing layers rule to these digital signals - routing layers enabled for this rule are Mid Layer 1 and 2. Priority=1. The analogue signals where also allocated to an 'Analogue' Net Class and assigned to another routing layers rule with the Top and Bottom Layers enabled. Priority=2 I also have a default rule with all the routing layers enabled. Priority=3.
Behaviour: For some reason when I run an Auto Route->All the signals in the digital Net Class are not routed. Signal fan-out vias are generated but then the connections on the inner layers are not made. It's not a problem of the router not having enough space to route the signals, the router simply stops. I could try to route the signals by hand but there are too many of them and it's clearly not the point of using an autorouter.
When I try to route the 'Digital' Net Class separately by going to Auto Route->Net Class... the same problem happens (on a board with no pre-routes). The autorouter doesn't do anything. Running an Auto Route-
Strangely enough if I replace the fan-out vias with pads and then I run Auto Route->Net Class... the connections are made.
Am I missing something, or is this a bug? Hope somebody out there is able to help!
Best regards, Patrick