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I'm designing a PCB using Altium and I have 3 signals that I want use in different layers:

  • 5Vcc
  • 3Vcc
  • GND

Initially, using Polygon Pour, I made GND planes at the top and bottom layers. However, as the complexity growth I decided to add aditional two, 3Vcc and 5Vcc, so that I would acess them through vias from top and bottom to 5Vcc and 3.3Vcc. This is my goal.

The doubts started when I saw at Layer Stack Manager, two buttons: "Add Layer" and "Add Plane"

I tried to add two internal layers, 5Vcc_layer and 3Vcc_Layer, I assigned to them 5Vcc and 3Vcc nets respectivelly. However, all the vias that I used to connect top or bottom to one of them(3Vcc or 5Vcc) appears as unrouted. The same happens when I added internal planes instead of internal layers.

  1. What the difference between Internal Layer and Internal Plane ?
  2. What should I do to reach my goal ?
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1 Answer 1

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Planes are "negative" layers. In the simplest situation they are all connected to one net. You can draw lines on the layer to split a plane and connect a certain region to one net and another region to a different net (for example, +5, +3.3 and -5V). The plane is assumed to be entirely copper except where lines, pads connected to a different net, cutouts etc. make it otherwise. Placing a thin track on a power plane is thus a bit awkward.

Using polygons on a layer you draw the outlines of where the copper should go and pour copper into that outline. The layer is assumed to have no copper except where you direct it to be placed, by a polygon or by pads etc.

Either one will likely get you to your desired goal. Using planes is probably more convenient if you are using them entirely or almost entirely for routing power.

As always, good component placement is key to grouping power connections so that a split plane or set of polygons can do a good job connecting things.

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