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adding vias to a part (symbol)

CSCNalu

Hi

I'm new to OrCAD and have only done one design so far but I'm trying to figure out how to stick vias into a thermal pad.  I have a QFN design from a friend and I can't tell if he did it as well but I've seen the board it created and he's got tented vias in the thermal pad and I can see from the design files that he's got the solder mask in a pattern and paste mask in a pattern so there's a clear place where the vias go but I don't see them on the package when I open it for edit.  Is there a way to do this or is it done when you're creating the board or was it somehow included into the package pin but I'm not seeing it when I open up the padstack editor?

Thanks

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  • excellon1

    Hi, for a ground pad on a QFN package what I like to do is create a padstack for the bonding pad and then use the multi drill function in the padstack editor to add as many drill holes to the pad as you want. The advantage is you don't have to add vias to the physical part to get the drill holes in the padstack. From a schematic perspective you are dealing with one pin even though you have multiple drill holes in that pad.
    As red pointed out you can also add vias etc.

    Here are a couple of pics to give you an idea. The first picture shows a rectangle pad in the layers section of the padstack editor. (16.6)

    The second pic shows how to add the drill holes from the parameters tab.

    You can stagger drill holes if you wish too. There is a wide latitude to customize the number of drills and spacing etc. Main benefit is that you are just basically dealing with one pad.

    All the best

    Paul.

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  • excellon1

    Hi, for a ground pad on a QFN package what I like to do is create a padstack for the bonding pad and then use the multi drill function in the padstack editor to add as many drill holes to the pad as you want. The advantage is you don't have to add vias to the physical part to get the drill holes in the padstack. From a schematic perspective you are dealing with one pin even though you have multiple drill holes in that pad.
    As red pointed out you can also add vias etc.

    Here are a couple of pics to give you an idea. The first picture shows a rectangle pad in the layers section of the padstack editor. (16.6)

    The second pic shows how to add the drill holes from the parameters tab.

    You can stagger drill holes if you wish too. There is a wide latitude to customize the number of drills and spacing etc. Main benefit is that you are just basically dealing with one pad.

    All the best

    Paul.

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