PCB Critique

Discussion in 'The Projects Forum' started by Return, Jul 29, 2014.

  1. Return

    Thread Starter New Member

    Jan 5, 2013
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    So I made a simple led sign that I etched myself but now want to have it manufactured.

    I never made a 2 layer board so here are some questions I have.

    1. You don't need via's when connecting tht components from top to bottom, right?

    2. I know it's good to have a ground plane but I'm using the Fritizing app and unsure how to go about this. Are their any downsides to not having one since I'm only using leds and not sensitive components?

    (Gold is top layer, bronze is bottom)
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The led 60 - 63 are missing a series resistor.

    Bertus
     
  3. Experimentonomen

    Member

    Feb 16, 2011
    331
    46
    What is this anyways ? looks like leds randomly tossed onto a pcb.
     
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    What do you mean by connecting tht components from top to bottom? If there are traces at the component which need to be connected, then vias are necessary. If there are traces on the top layer (eg the layer opposite where you're soldering) then a via is necessary. I almost always use a via and always solder from the side opposite the components. I don't specify a via only when having mounting holes drilled.

    As far as the ground plane, switching LEDs can generate lot of noise and a ground plane will help. It also simplified the trace routing. I don't use Fritzing, but the app I use has a simple procedure for adding a ground plane (or power plane. I use ExpressPCB).
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    There is a slight difference between a "via" and a "plated through hole"..
    A via is a plated through hole used for the purpose of electrically connecting traces from one layer to the other
    A plated through hole accomplishes the same task but is also meant to be used as a solder point/hole for through hole components.

    You don't need to add a via if the plated through hole is making the connection already.

    And you more than likely will not need a ground plane if you don't want one..
    A copper pour on both sides (assuming double sided) will just help with the manufacturing process and can be used to create ground/signal planes if needed.
    But if fritzing can't do it then don't worry about it.
     
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  6. Return

    Thread Starter New Member

    Jan 5, 2013
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    60 - 63 are connected to R15

    I had jumpers connecting the resistors to gnd that are now the top traces. I'll go ahead and use a via to connect them to the bottom plane then.
     
  7. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Then R15 is not connected correctly, as it is in series with lots of other strings.

    Bertus
     
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  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    yeah it doesn't look right.. But my eyes are going goofy just to follow that board..
     
  9. Return

    Thread Starter New Member

    Jan 5, 2013
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    Thanks I do see it now.
     
  10. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    A recommendation: Fatter traces rarely hurt -- when you have the room -- and often help with signal integrity and voltage drops on long, high-current runs. They also help marginally with heat management.

    The only drawback is that fat traces draw more heat from a solder pad during soldering. This is rarely a problem with automated solder wave or reflow, but can cause problems when hand soldering.
     
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  11. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Using a PCB vendor is a "garbage in, garbage out" process: they tend to build what you say, not what you meant. So check and recheck it carefully.

    No, but typically to get from top to bottom you use a "plated thru hole" which is the industry standard. There should be no additional cost for this step as it is standard in the vendor's process.

    You may be able to negotiate a slightly lower cost by not plating thru, but this is so slight it isn't worth the bother.

    Somewhat curiously, adding non-plated thru holes to a plated thru hole board usually entails an extra cost, as the vendor needs an extra drilling step to do this.
    You will be safe without a ground plane, but do use thicker traces as suggested.
     
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  12. Lestraveled

    Well-Known Member

    May 19, 2014
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    I agree with joey999, fatten up you traces, especially the common/ground connection. There are a lot of parts pulling current through that trace.

    There is another benefit to fatter traces; less chance that the trace will be undercut during etching. Modern PCB manufacturers are really good with small traces. It's just a good thing to do. There is no downside to a fatter power trace if there is space to spare.

    Mark
     
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  13. Sensacell

    Well-Known Member

    Jun 19, 2012
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    If at all possible, consider orienting all the LEDs in the same direction, this saves so much headache when assembling and debugging a board like this.

    Use a heavy power traces with thinner ones coming off to service the smaller branch circuits.
     
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  14. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    And ditch fritzing and move to a better PCB design program.. :)
    Then you can do all the fun stuff like copper pours,thermal reliefs,etc.. with ease.

    I'll recommend Diptrace.. as they have a free version and IMO its a very easy to learn software with a decent library and simple new part creation process..
     
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