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Return straps vs actual jumper wire on 2 layer board, which is better?

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  • Return straps vs actual jumper wire on 2 layer board, which is better?

    Hi everyone,

    I'd like to know what you think about this problem. It's not really a problem for me, just want to know which one is better.

    I am able to route all my signals/tracks on top layer on 2 layer board, bottom layer is all ground, except 5 traces that you can see in blue. Now 4 for these traces are breaking the path of return current for many other traces, ( if my terminology of return currents is correct ). So I added return strap for all those traces. One approach is this that you see in image below. Second approach that I think is the obvious jumper wire on the bottom side of the board.

    My confusion is understanding what will happen to return currents (for all the channel tracks) if jumper wire is used on the bottom, will it better than return straps, or are they both almost the same? If jumper wire is used on the bottom side, can we consider it like as we are creating tracks on invisible third layer?

    Want to hear your opinions.

    Click image for larger version  Name:	Untitled.png Views:	0 Size:	192.8 KB ID:	18510

    Thank you for your time.


  • #2
    - If GND is broken under the tracks, it may be sometimes hard to tell where exactly the return currents will flow e.g. it may go around the gap, through the neighbor signals, etc.
    - If you use jumper wires, that would be like a 3th layer.


    • #3
      Thanks robert,

      For now I am going with the jumpers.

      Placing jumper wires on bottom vs top of the board, does it make any difference? I think bottom would be fine because the GND layer is more close to it that way.

      I wish I could use 4 layer board and avoid all this but it's expensive here in India (if not importing from outside). For the same 25 cm² board area, 4 layer board is double the price 2 layer board and that too for order quantity of 100 pieces. 😥


      • #4
        - don't forget, you will need to make and solder the wires, that will add some extra cost on your 2 layer pcb
        - if you place them on the bottom, yes, they will be closer to the gnd plane


        • #5
          What about using 0 ohm resistors? 1206 or 2512 allow multiple traces underneath them. Spacing between the traces need to be closer there of course.