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I am on a 4 layer PCB and one of the layer is a power allocated plane. I don't have only one rail but 4 or 5. So far I have made some traces between the differents points where the components and vias are connected to each other on this rail. I suppose this configuration (keeping only traces) can probably work.

Now, I found out that most of pcb design are using polygons instead of only trace to create power layer rails. I know how to make polygon, but what I have difficulties with, is about drawing them properly to make them to be adjacent properly to each other (I suppose the game is to fill the full plane by having polygon to span all the plane leaving no "hole" on the plane, right ?). By this I mean : I have difficulties to establish shape, width and height. I understand that a possibilty is to coat the trace and to expand. But how to expând properly ?

How is it recommended to process ?

PS: I am using Altium

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  • \$\begingroup\$ Which CAD software are you using? \$\endgroup\$
    – filo
    Sep 11 '16 at 5:58
  • \$\begingroup\$ @filo I use Altium \$\endgroup\$
    – chris
    Sep 11 '16 at 6:24
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It all depends on which PCB design software you're using.

For example, with the popular Eagle software to create a plane you simply put a polygon over the whole board - but then give it a low priority to allow every other feature to dominate and "carve it up" according to the required separation parameters. By labelling it with a name (e.g. "GND"), Eagle also will automatically connect to the polygon where it needs to.

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  • \$\begingroup\$ I use Alitum Designer \$\endgroup\$
    – chris
    Sep 11 '16 at 6:24
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I searched for a while and it seems the strategy is to use split planes funtins in Altium instead of polygon

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First thing on a pcb is the placing of the given things (connectors, mechanical drillings etc) Afterwards I suggest to make a power concept and try to split the different power regions up. What comes here are also the capacitors to stabilize everything, where do you need those?

To make things easier on the middle layers you can route the simple power on top or bottom. By simple I mean i.e. simple 5V logic gates which are resistant and slow. They don't need to necessarily be on the middle layer routed and you have more space for your big stabilizing planes. If you have a good placing you can make those distincted regions of polygons or split planes really big and stable (split planes for gnd is maybe easier but for power I suggest normal polygons). You can make polygons with place->polygon, it's the simplest way. For the fine work i suggest to right clicking the polygon and in settings to go the the dots of the polygon and readjust them to the desired coordinates.

If something doesn't fit in well, replace it. Usually you have to do this 2-3 at least until you have these power sectors I was talking about. It's an iterative work and you can do this over and over until it's perfect.

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