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How to check copper to copper clearance?

Tom Nguyen

I use OrCAD PCB Designer Professional 17.2.

My PCB partners require 6 mil clearance between copper objects.

The board has 4 layers. I use a through via array to connect a plane on layer 3 and other on layer 4. To ensure 6 mil clearance, I must add plane on layer 1 and 2.

If I omit layer 1, I want the layout to notice me the error.

Question is How to set up constraint to solve the above problem?

Please refer the below picture.

Layer 4

Layer 3

Layer 2

Layer 1

Layer 1

Thanks,

Tom

  • masamasa

    why do you want to remove the plane from layer 1?

    if you really want to make sure you accidentally do not delete the plane, you can simply "fix" the shape so that you accidentally do not remove it from layer 1.

  • Tom Nguyen
    in reply to masamasa

    "if you really want to make sure you accidentally do not delete the plane, you can simply "fix" the shape so that you accidentally remove it from layer 1."

    => That is exactly what I do now.

    But if we review a 10-layer board, how can we ensure all planes are added. And I want a tool to check that.

  • masamasa
    in reply to Tom Nguyen

    if there is no plane on layer 1, you should get antenna vias.

    you can find antenna vias in the dangling line, via and antenna report.

    you can use this report for only the top or bottom layer not for the inner layers like layers 2 and 3.

    i always check the report as i do not want to have antenna vias in my design.

  • Tom Nguyen
    in reply to masamasa

    Because I use through vias, there will be a lot of antenna vias (that use for signals).

    I think your solution will be difficult to solve forgetting plane on inner layer.

  • masamasa
    in reply to Tom Nguyen

    another idea would be to use a route keepout.

    the inner shape in blue in your layout should not be a dynamic shape but a static shape.

    then place a route keepout over the static shape and the route keepout area should be overlapped with the outer shape in red.

    you should set the property of the route keepout with via allowed.

    since the static shape in blue is still in the keepout area, it should give you an error.

    you should waive the error so you have no valid error now.

    if you acciendally remove the static shape in blue, you should get a new error since the shape in red has a new shape within the keepout area.

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