Electronics > PCB/EDA/CAD

Via and ground plane question

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hozone:
Hello,

I'm an amateur PCB designer.
I usually design 2 layer PCB.
Almost always I build boards with two plane, one ground and one power.
Sometimes I use VIAs to connect GND and PWR, but most of the time ground and power lines are directly routed to the pins that needs GND and VCC.
I'm lately watching pro PCBs, I've found that GND and PWR vias are heavy used, expecially GND.
I'm wondering if a better design would be to use GND and PWR VIAs "ALMOST ALWAYS".

Thanks for any of your tips!

Doctorandus_P:
A good ground plane is a very important part of a PCB. One of the guys at altium has made a 2 hour (and some minutes) video about it, and if you're into improving your PCB design skills it really is worth watching.

For a two layer PCB, usually all smt stuff is on the top, and this means the GND plane has to be on the bottom to be able to keep it continuous. As a result everything is connected with via's to the GND plane.

Normally a lot of decoupling capacitors are spread around the PCB. The result of this is that the power supply only has to deliver a DC current and the AC ripple current at higher frequencies is quite low. This also means that the power supply just has to be able to deliver this current. Fairly wide tracks to lower the resistance are usually used, but the power supply itself does not really need a plane.

But this is just a few rules of thumb and a gross simplification. That 2 hour video from altium is from a man with a grey beard who knows his stuff. Robert Feranec also has quite a lot of videos about PCB design

bpiphany:
Here's a Feranec video about power planes or no.



I've had many of my hobbyist PCB layout presumptions challenged by watching his videos.

hozone:
Thanks all!

I've watch that video. Power plane I would like to use is not for high current reason, it's to avoid power route, to give more "space" for signal routes.

This video clarify half of my doubts:


It seems, in a few:
* one via per GND, on ground plane
* one via per PWR pin, on power plane

BUT, on the video bpiphany suggested, seems power plane are "evil".

So now I've a doubt, to power plane or not?

I'm speaking of 2 layer boards.

Feynman:
While a solid ground plane should be beneficial in most designs, a power plane is often times optional (but certainly not "evil" per se).

In designs that are rather simple (4 or 6 layers) I almost never use power planes: When possible, I make half the layers solid GND planes. And power is routed and/or poured on the signal layers.

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