How to create proper ground plane


#1

Hello everyone, I’m fairly new to kicad and just learning the ropes. One of the things I’ve seen to be very important is creating a ground plane to limit the number of traces and in general just make things cleaner and easier.

I’ve done as such by creating a zone and filling it, however, lots of my components are left disconnected because of other components and traces in the way. I’ve included two pictures of how I’ve done it and would love to know if there is a better way.

Thanks!


#2

Are both top and bottom fills GND? I think you might have to do some via stitching to connect them. (Basically a connection between the top and bottom GND planes to connect them) Kind of hard to tell in the attached pictures though. In some cases you may have to manually route because the fill zones generally have a larger clearance than you have set for tracks.


#3

I know they have a very large clearance by default. (Zones to not follow the global clearance definitions. They have their own settings.)
Is there a reason to keep it that way?


#4

Not my board so I was reluctant to mention that plus I don’t think that solves all the problem. I was only intending to give a safe starting point until more knowledgeable people checked in. :wink:

It probably isn’t obvious until you have done them that the top and bottom ground planes don’t automatically connect so that’s the first thing to look at. I just noticed that there is a minimum copper width in the zone settings. I’ve never noticed that but it would be another setting to look at.


#5

Both fill layers are GND, I have heard of via stitching before but was unsure as to if I should do that at the very end, or if there was anything else, thanks!


#6

[quote=“Rene_Poschl, post:3, topic:8387”]
I know they have a very large clearance by default. (Zones to not follow the global clearance definitions. They have their own settings.)Is there a reason to keep it that way?
[/quote]After thinking about this there is a couple ways to take this question. One is ‘in general’ and the other is specific to this board.

In general I’m sure the defaults are large for two reasons. A large clearance for voltage differential and a large minimum for current. Having large defaults probably prevents poor design choices on generic board. People dealing with high voltage and current are probably aware of this before they even start. That’s why I’d suggest making sure the top and bottom zones get tied in areas that might solve the problem.

At specific board level the OP would have to answer the question. It isn’t just a matter of dropping down the defaults so you can say you got the pour to flow everywhere.


#7

You may have to look it up. It isn’t directly supported in Kicad but there are ways. Just search the forum.


#8

I looked at your screenshot a bit. A few problems will be solved by reducing the clearance for zones.
Some components could be placed better.
Check your vbus trace. (Run the design rule check (DRC)!)

Via stitching will be required thought.


#9

There are actually serious technical reasons to use planes (for power rails as well as ground). For single-ended digital signals the return current is in the nearest plane.

As for clearances: unless you have a requirement for high voltage separation, there is no reason the zone clearances can’t be the same as the trace clearances.

Now the main thing with planes in a two-layer board is that component placement and signal routing break the plane. So you’ll end up with sections isolated from each other and you’ll have to connect them with traces and/or via stitching.


#10

Okay, I’ve taken the first few suggestions into account and this is what I’ve come up with. I think DRC came back with nothing, but humans are always more helpful :joy:

Is there anything else I need to take into consideration?


#11

ANT for antenna? All theoretical on my part but I’ve read sometimes special precautions need to be taken for high frequencies. I’m not qualified to give real opinions though but now is the time to make sure.


#12

If it is some sort of high frequency module with an integrated antenna then it might define a no copper zone in some areas. @siftyy look closely at the datasheet of this component. Do they mention something about keepout?


#13

I’ll be damned, there’s definitely a keep out zone, didn’t even realize


#14

@siftyy,
I can’t help but noticed the BGM111 module on your board, what do you use to program it ? what bootloader does it have?

Thanks


#15

Try moving most of the long traces on the bottom up to the top, if you can. The ground plane works best if it has as few holes in it as possible, and a long trace through will effectively split it in two.

The bus on the bottom could probably be run almost its entire length on the top.