Ground and Power plane in the same layer [Solved]

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Hello All,

To start I am a newbie in PCB design and therefore in Kicad software.

My project will basically drive a DC motor and I am not expecting more than 200mA to be running across the traces and also for a short period, due to that and to few components needed on my project I will stick with a 2-layer PCB.

So I was wondering in having both the ground and power plane in the same layer (bottom), this lead me to some questions:

1 - Is there any need at all of having ground and power plane in the same layer (since the current is small), moreover is this a valid design or just something stupid?

2 - I tried to create the two areas in Kicad, the GND plane I managed to create the area and fill it correctly but the Power plane I was only able to create the area, I couldn’t fill it (tried everything: using menu and shortcuts, “B”). Is this an issue or just Kicad saying that there is no reason at all to have two different planes in the same layer?

3 - Is there any recommendation on a PCB book for beginners (PCB not Kicad) ?

Regards,

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  1. There usually isn’t a need for planes in a small, two layer PCB, but it can help with design if you have the room, as it’s usually faster than running a GND and PWR “bus” trace.
    You’ll want a solid ground plane (and power sometimes) when you start dealing with higher currents or sensitive noise situations. Avoid running traces inside the planes, as cutting up a ground plane tends to redirect return currents and can cause noise issues if there’s stuff like fast edges or noisy power rails.

  2. Is there anything connected to the power fill? Like are there pins with the same net in the area? It won’t pour if not. Is the power fill inside the ground fill? If so, try changing the priority of one of the zones, the one.

  3. I really like reading white papers from folks like Texas Instruments, depending on the topic (ESD, grounding, etc.). Haven’t read any books myself, sorry.

EDIT: Gotit.

1 Like
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Thank you all for the answer! Actually the zone wasn’t with a pad/net within it. I just corrected and it worked.
@jwpartain1 thank you for the other answers.

Regards,

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It is quite valid and there are a number of reasons you may want multiple pour areas on one layer

  • Thermal - Pour is a good way to maximize Copper cooling areas
  • PCB current, Similar to thermal, if you cannot have widest trace everywhere, wider where possible lowers the total i2r power loss in the PCB
  • Shielding
  • and of course, for partial plane use, where traces are usually manually adjusted to permit maximal coppers.