Ground Pour

by gaussmarkov

This is a multi-page tutorial about creating ground pour on an Eagle layout. The picture above shows an example. Note that the ground copper fills in space underneath resistors R1, R2, R4, and R6. It also runs up under the stack of components on the right and in between the +9V trace and C1.

First, I have a short editorial. Many people make a distinction between ground pour and a ground plane. What you see above is ground pour. In PCB fabrication, a ground plane is a layer of copper that is distinct from the layers for signal and power traces. Quoting the wikipedia article Ground plane,

A ground plane in PCB assembly is a layer of copper that appears to most signals as an infinite ground potential. This helps reduce noise and helps ensure that all integrated circuits within a system compare different signals’ voltages to the same potential.

It also serves to make the circuit design easier, allowing the designer to ground anything without having to run multiple tracks; the component needing grounding is routed directly to the ground plane on another layer.

Ground planes can also be placed on adjacent layers to power planes creating a large parallel plate capacitor that helps filter the power supply.

One more thing before we start. You need to have my Eagle environment for this tutorial. If you are following along with your version of Eagle, type in each of the following six commands:

grid mil 50 2
ch lay bot
ch wid 40
ch pour solid
ch the off
ch orph off
ch iso 40
set polygon_rat on

These set the units of measurement, make sure we are working on the right layer (bottom), set the trace width to 40mils, and some other stuff related to the Eagle POLYGON command that makes the ground pour.


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21 Responses to “Ground Pour”

  1. Kirby said:

    great tutorial… exactly what I was looking for

    Posted 14.11.2007 at 9:44 am

  2. gaussmarkov said:

    Excellent. 🙂 There is more. I have the images already. I just have to find the time. 😉

    Posted 14.11.2007 at 10:00 am

  3. Auke Haarsma said:

    Keep m coming! Great tutorial!

    Posted 08.02.2008 at 5:16 am

  4. the said:

    ch lay bot does not work…

    got a tip?

    greets

    Posted 01.03.2008 at 6:52 am

  5. gaussmarkov said:

    the,

    your message is too cryptic to offer a tip. there are times when “change layer bottom” does not prevent the route tool from reverting to the top layer when you are starting a new trace from an existing trace that is in the top layer. that’s all that comes to mind and that’s just eagle. you have to take your mouse up to the route tool bar and click on the layer you want.

    good luck, paul

    Posted 03.03.2008 at 8:59 am

  6. Roman said:

    Thanks for the tutorial AND the libraries, this is extremely useful for noobs like me. Your detailed description of the ground pour is the best I’ve seen on the Net, thanks for taking time to do this!

    Posted 24.03.2008 at 6:20 am

  7. gaussmarkov said:

    hey Roman,

    it’s a pleasure to get appreciative feedback like yours!

    cheers, paul

    Posted 24.03.2008 at 8:44 pm

  8. Allan said:

    Loving these tutorials, got my first pcbs started with your help. Thanks.

    I’m having trouble getting my top and bottom layer pours to ‘work together’ they are wiping out traces in each ones level. Like this:
    http://i26.photobucket.com/albums/c143/ringworm_1974/Picture1.png

    Any tips? is there a way to make a board with just a single layer, this would seem to make sense for small stompbox projects, or am i misunderstanding something fundamental about pcb design?

    Posted 23.12.2008 at 4:29 am

  9. Allan said:

    I got it figured out! I was clicking on the pour rather than the traces to change the layer.

    Posted 30.01.2009 at 7:02 am

  10. Rufio said:

    Great tutorail gauss, thanks for the librarys. I made my first pcb, i don’t know if its going to work, but looks ok.

    Are you going to continue this tuto? I had trouble withe the tool “autorute”, didn’t like the way the ground line came out.
    How do you make de ground line stays around the pcb?
    And finally how do i export my pcb to another program, like photoshop, to print it, with other pcbs?

    Posted 19.06.2009 at 5:20 pm

  11. Anonymous said:

    good tuto

    Posted 12.09.2009 at 3:29 pm

  12. Anonymous said:

    nice ..

    Posted 12.09.2009 at 3:29 pm

  13. RNFR said:

    i’ve found that ch wid 1 makes your ground pour edged much cleaner and nicer looking. give it a shot!

    and thanks GM, i still refer here often!

    Posted 07.11.2009 at 1:57 pm

  14. Parker said:

    Great tutorial, but what do those six commands actually do? Becasue now eagle thinks my board is actually 3.7 metres across and I cant seem to change it back…

    Posted 08.03.2010 at 2:26 pm

  15. Parker said:

    Ah sorry my mistake I was assuming ‘mil’ was short for ‘millimetres’ which apparently it isnt? Must be a yank thing…
    Again this is a fantastic tutorial – cheers 😀

    Posted 09.03.2010 at 11:40 am

  16. Hawg said:

    gm-

    I also got the error when I entered the ch lay bot command, because I was still working from the new->schematic from the last tutorial.

    If anyone else gets the error, it might be because you are working on a schematic instead of a board. Right click your project and go new ->board.

    Posted 08.06.2010 at 12:48 pm

  17. paijo said:

    this is what i need…thanks

    Posted 11.06.2010 at 1:55 am

  18. John said:

    Parker-

    A ‘mil’ is 0.001 inches.
    I’ve seen lots of people mistake it as an abbreviation for millimeter, however
    1 mil = 0.0254 millimeters

    Posted 02.09.2010 at 4:49 pm

  19. Tony said:

    could you change c4 or c1 to filter out some treble or simulate rolling your treble knob on your guitar back as I have had no luck wiring in a treble control in this circuit and I like with the treble all yhe way off

    Posted 27.11.2010 at 1:16 pm

  20. LC said:

    Why does only the “square” package show up for every device in the supply library? Did I do something wrong?

    Posted 05.02.2011 at 1:11 am

  21. EagleCAD PCB Workflow | Daktek said:

    […] Create a ground pour using the polygon tool […]

    Posted 01.04.2013 at 12:11 am