Ground plane appearance and PCB design

Discussion in 'The Projects Forum' started by ozmo, May 8, 2011.

  1. ozmo

    Thread Starter New Member

    Dec 15, 2009
    I'm using an Arduino GPS shield which provides a header, power, and signal routing for a GPS chip.

    The GPS datasheet specifies that pins 1 and 5 are GND.

    The following is a part of the PCB layout where the GPS header plugs in. Pin 1 is the top pad, and Pin 5 is 5th from the top. The corresponding pads for those pins aren't connected to anything on the board it seems.

    Pic 1 (Layout):


    Pic 2 (PCB):


    Pic 3 (PCB) - I tried to see if I could see the other layers so I held the board up to the light:

    So my questions are:

    1) Are pins 1 and 5 in fact connected to a ground plane? If not, how are they grounded?
    2) Is the ground plane the dark green layer that's visible in some areas?
    3) If #2 is true, how come you can see through some dark-green parts of the board (like right next to the header pin traces), and not others?

    Also, the schematic and layout are available at this link:

    Thanks in advance for any help. I know it might be kind of a tedious question, but I search both the forums and the web for some answer and wasn't able to figure it out, so hopefully any info will benefit others as well.
    Last edited: May 8, 2011
  2. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    I may be going blind - but it looks connected to me right there in pic #2
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    maybe the difference is simply digital ground and power ground. Both pins are connected as viewed in the pictures(nice that you posted them). And yes; the large green areas are a ground plane. The view through the board is also complicated by the traces on the opposite side blocking light in some areas and letting it show through other similar areas.
  4. ozmo

    Thread Starter New Member

    Dec 15, 2009
    In a mass-made PCB like this, how is the ground plane made? Is it something like, lay down a layer of copper, then apply an insulating lacquer with the exception of pads where you would expect a ground, and then lay down copper traces, and then apply the final layer of insulating lacquer?

    Also, would a mass-manufactured ground plane show up in an EagleCAD layout? The layout for this board doesn't seem to (the direct link is So I guess the manufactured takes whatever pads are marked GND, and leaves an opening in the insulating lacquer for it?
  5. osterchrisi

    New Member

    May 9, 2011
    As far as I know, it's more or less the other way round: First there is ground everywhere, then they etch away what shouldn't be there (the lines between the traces) and the last step is to apply the solder mask according to provided drawings. Correct me if I'm wrong...