A better way to build grounds on a copper clad board?

Discussion in 'Electronics Resources' started by Fuji, Nov 24, 2014.

  1. Fuji

    Thread Starter Member

    Nov 8, 2014
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    - I use EAGLE to build my schematics and boards. I have a question regarding how to create ground plains on clad board. Would it be better for all grounds of the components to be connected to the source that powers the entire board? I've heard people connecting grounds of circuits that are close by to another circuits ground instead of making netting the lines for each component towards the ground source of the entire circuit.

    - I use a double sided clad board, but my components are all SMD/SMT. Is there really a point to use the second side of the copper clad board in this case? I don't have through-hole components. Perhaps creating a ground plain spanning across the outer part of the top single side of the board where all the circuits are located would work?
     
    Last edited: Nov 24, 2014
  2. MrChips

    Moderator

    Oct 2, 2009
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    It depends on specific design and application. Is this analog or digital? Mixed signal?
    What is your maximum operating frequency? What is the the frequency of your signals?
    What are your supply currents and voltages?

    If you are going to create a double sided board and are concerned about performance at high frequencies it is generally accepted to make the lower layer a complete ground plane. This would not apply for a mixed signal application.

    The devil is in the details.
     
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  3. Fuji

    Thread Starter Member

    Nov 8, 2014
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    Im using a 9v power source. XT oscillator (1Mhz) as well. It is digital I believe since Im using a microcontroller.

    So for low frequency, it would be safe to use a single sided clad board? If this is the case, I can probably just make a ground plain across the sides of the board and then connect all component grounds to that plain?
     
    Last edited: Nov 24, 2014
  4. MrChips

    Moderator

    Oct 2, 2009
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    What chip are you using?
    For a MCU driven by a 1MHz XTAL oscillator, a single sided board without a ground plane should work just fine.
    If you are etching your own board it is best to leave as much copper on the board as possible. Hence a ground plane is not such a bad idea.
     
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  5. Fuji

    Thread Starter Member

    Nov 8, 2014
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    Thanks for the feedback.

    I am using PIC16F84A at the moment and soon to switch over to SOIC microcontroller to make it smaller.

    Does the width of the wire/net lines that are connecting all components together effect the circuitry as well? With 9v power, how much width for the track lines would be preferable? Can the ground wire be thicker than the track lines of the components? Im using a width of 0.1 for all my track lines since it is a really small board.
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    What are the units for 0.1 width? Inches, cm, mm?
    The width will be dictated by the current in the wire and the thickness of the copper clad.

    1oz copper clad is standard.
    Typical pin to pin traces are 10, 12, 15 thou (mils) i.e. 1/1000 of an inch.
    It depends on who is etching the board for you. A commercial PCB house can do 6 or 7 thou.
    If you are etching the board yourself you want 15-25 thou. It also depends on whether you are squeezing traces in between 0.1" pitch pins.

    http://www.hardwarebook.info/PCB_trace
     
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  7. Fuji

    Thread Starter Member

    Nov 8, 2014
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    Sorry for not replying sooner. I was busy.

    I believe it is 0.1mm.

    Thanks for the link. Shows exactly what width of trace to use and board thickness.
     
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