PCB : 90 Bends FAIL?

Discussion in 'The Projects Forum' started by mxabeles, Apr 29, 2010.

  1. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    Hi there,
    finally making switch from perfboard to etching my own PCBs.
    I have finished two designs on eagle (a simple 4017 led chaser and strange square wave x4 synth).
    I have "heard" that 90 angles on traces are bad for "high speed" data. Now does that include things like audible pitches or is it just speaking of very high speed data communication devices?
    Thanks.
    Max
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    I do not think this is important in the audio range. It could be that your PCB software has an option to produce rounded corners.
     
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  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    IIRC this starts to matter for high speed data, that is in the 1GHz+ range. Certainly it doesn´t matter anywhere up to tens of megahertz, and for sure not in audio range.

    Other problem with sharp corners could be higher possibilty of traces peeling of from the board, but even that should generally never happen.
     
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  4. t06afre

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    May 11, 2009
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    But since you have started this thread. Why not post your PCB for a review. I have understood you are new to this field.
     
  5. Rick Martin

    Active Member

    Jun 14, 2009
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    Right angles in general in regards to PCB design is considered a no no, atleast that is what I and everyone I know in the industry adheres to. I am not sure of the reason to be honest, we just all use two 45 degree bends to achieve a 90 degree otherwise when routing you just avoid the situation that requires 90 degree angles.
     
  6. t06afre

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    May 11, 2009
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  7. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    just a simple led chaser
     
  8. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    thanks for the input
     
  9. Rick Martin

    Active Member

    Jun 14, 2009
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    It would still be good practice for hobbyist or not to eliminate all 90 degree track bends.
     
  10. t06afre

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    May 11, 2009
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    I took a look at your PCB. Some of the tracks are placed very close to the pads. This pads are marked PADx Since you have space on your board you should increase the spacing. On a DIY PCB you have not solder stop layer. tracks and pads are just bare copper
     
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  11. retched

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    Dec 5, 2009
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    I would agree. Increase your spacing.

    It can ONLY help.

    As t06afre said, you only have bare copper. Professionally made PCBs coat the copper in tin then a sealer (thats the green color(on most) PCBs)

    If you need higher current traces, you can solder a wire along the trace, after making it as wide as you have available on the PCB.
     
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  12. n1ist

    Active Member

    Mar 8, 2009
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    I would make a few changes:
    - Add a 100nF bypass cap for the 4017; they tend to reset on current glitches
    - Use thicker traces for power and ground, and try to make the ground to the 4017 a bit more direct
    - I like to place 100nF from the input to ground and output to ground right next to the regulator
    - The LEDs will need a current-limiting resistor between LED_GND and GND
    - You may want to make R1 a pot so you can adjust the blink rate
    - There are no mounting holes

    Here's the schematic and PCB layouts I used for this circuit (SMT and thruhole). I included the LEDs on the board, and yes, the pinout of the 4017 is a pain...
    /mike
     
    Last edited: May 7, 2010
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