Opening a window in a copper fill

Layout
1

Hello!

I have the following problem. On a single board, I have components in 5V and some others in 3.3V. So I would need to have 2 power planes in one. Of course, if I add 2 layers, I can have a power plane of each, but I would like to stay in 4 layers, so I thought I could create a 3.3V power area inside of a 5V area. For all topologies without a hole, it’s easy, For example if I have a C shaped area, I can draw the outline of the C, then the outline of the internal part of the C and I’m done. As for a hollow area, I tried to draw a large 5V area on the whole board, then a smaller 3.3V area inside, but unfortunately it doesnt do what I want. when looking at the power level, I have a single solid block. Is there a solution for that? I could also draw a C with an arbitrarily small aperture, but I think there might be a more straightforward way to do it.

Thanks,

Pascal

2

Change the copper fill priorities between layers.

You could keep the 5V at 0, and set the 3.3V to e.g. 1.

3

You need to change the priority of one of the fills. By default they are all 0, that will merge them no matter what nets they are assigned to. Set one of the fills to Priority 1.

4

Hello guys!

Thanks for your replies, it was quick!
I changed the priority of the middle windows to 1.

Windows

Another question: the 2 middle windows have the same voltage
(3.3), so I guess I can assign them to the same priority, right?

Pascal

5

In this case, you probably can.

However, the concept of a Filled Zone and priority level is not based upon the same voltage level.

I don’t have an easy to grab graphic to share, but consider the concept of using the opposite external layer as a PCB heat-sink for the part on the opposite side of the board.

6

No harm in that, unless something overlaps anew in which case you just keep changing priorities until the drawing sequence is right.

7

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