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I know there are multiple questions about this topic, but I didn't found an exact answer to my question.

My situation: I'm having a 2 layer PCB. On the PCB there are multiple SMD components and traces both of them on the top and on the bottom side. All signals and power traces (+5V and +3V3) are already routed. Now my idea was to create a ground plane: one on the top and one on the bottom layer.


My questions:

  1. Is it a good idea to have a ground plane on both layers?
  2. Should the ground planes be connected with vias or is it enough that they are connected through the GND pads of my USB and Ethernet connector?

If anyone needs additional information, please write a comment and I will try to provide this information.


Edit: I want to add some future details about the PCB. The PCB has a size of about 60x60mm. The main components on the board are a microcontroller from Microchip (PIC32MZ) and a ethernet PHY from Texas Instruments (DP83848). Furthermore the board contains a USB-B and ethernet port. The 5V from the USB port is used as the power supply of the device.

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    \$\begingroup\$ That would be a ground fill.. not a ground plane... Whether or not it helps is open to debate. \$\endgroup\$ – Trevor_G Apr 13 '18 at 20:02
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    \$\begingroup\$ Controlled impedances and stray capacitance must be considered along with EMC. Nothing defined, no answer possible. \$\endgroup\$ – Sunnyskyguy EE75 Apr 13 '18 at 20:04
  • \$\begingroup\$ @TonyStewartEEsince1975: Could you give an example of the information which would be needed to answer this question. \$\endgroup\$ – Benjamin J. Apr 13 '18 at 20:13
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    \$\begingroup\$ electronics.stackexchange.com/… \$\endgroup\$ – Sunnyskyguy EE75 Apr 13 '18 at 20:50
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Create a copper pour/fill on the top and bottom and stitch them with as many small vias as is reasonably possible. Try to place a GND stitch via next to any signal or power vias you are using to allow return current to flow to the opposite side. Also stitching the entire perimeter of the board while respecting the board houses copper to edge rule is often recommended. Some PCB software has the functionality to automatically fill your board with such stitching vias.

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