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Protrusion makes short in PCB. How to Avoid or Check Protrusion in Allegro PCB Editor.

MW202412035844

This pic is ETCH Gerber screenshot of my design.

Green is the part of the whole shape, red circle mark is the protrusion without connection caused by bigger void than via above the protrusion. This protrusion will bend and touch to adjacent vias in lamination like the small picture, short between shape protrusion and via. Like the last picture, blue protrusion bends and shorts to vias.

Please advise how to avoid protrusion or check when protrusion happen. Thanks!

   

  • 0

    Hey  ,

    I think you can utilize the Void Sliver check and Acid Trap area check available in DFF Constraints to address protrusions and ensure their detection during the design process.

    1. Void Sliver Check (requires Allegro PCB Venture License):

    This ensures that narrow air gaps caused by voids are detected.

    >>Access Constraint Manager via Setup > Constraints.

    >>Navigate to Manufacturing > DFF Constraint Set > Copper Features.

    >>Define the minimum width for air gaps under Void Slivers and assign this constraint to your design.

    >>Enable Analysis Mode and run Tools > Update DRC to flag gaps where protrusions might occur.


    2. Acid Trap Check (no special license required):

    This prevents acid traps that form due to improper trace-to-pad alignment.

    >>In Constraint Manager, go to Manufacturing > DFF Constraint Set > Copper Features.

    >>Specify the minimum area for air gaps under Acid Traps and assign the constraint set to your design.

    >>Enable Analysis Mode and run Tools > Update DRC to flag potential acid trap zones.

    Hope it helps!

    Cheers :)

  • 0 in reply to Gowtham P

    Hi ,

    Thanks for your reply! I've tried the way you said, it doesn't work. maybe there is confusion on my question. I updated it, could you please advise again? Thanks!

  • 0

    In the Global Dynamic Shape Parameters, you can set a value in the "Suppress shapes less than" box.

    This should get rid of the little slivers.

  • 0 in reply to avant

    Thanks for your reply! We have set this value so that the shapes could get into BGA narrow area between via to via, as you can see the narrow green shapes between each black square. But for the narrow shapes, one of be termination is not connected, that’s the protrusion which cause short.

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