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Issue with Via-Via Constraints

WG20250730781

Hi all, 

I have an issue with the via-via constraints of my design.

1. Normally, the via-via distance is defined in the constraints manager. However, the thru via to thru via spacing is defined by the air gap between the two vias. The issue is that this air gap accounts for the pad size to pad size distance of the via, and not the hole-to-hole distance itself. Often in manufacturing, hole-to-hole distance is more important in fabrication. How do I account for actual hole-to hole distance itself?

2. Under the constraints manager, there is a column that specifies 'hole to hole'. When I double click it, it pops up another window and further classifies into so many other line items:



However, under the general constraints manager window, there is already 'Thru via to Thru via'. How are these two different?

I appreciate some professional help.

Thank you.

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  • 0

    Well, look at it as ... you have granularity in the way you measure and constrain distance between vias. Allegro offers all the options: from the hole center, the hole edge, the pad edge ... If you input some values there and start moving 2 vias closer and further apart, you'll see. Try also to vary the size of the pad in your tests

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  • 0

    Well, look at it as ... you have granularity in the way you measure and constrain distance between vias. Allegro offers all the options: from the hole center, the hole edge, the pad edge ... If you input some values there and start moving 2 vias closer and further apart, you'll see. Try also to vary the size of the pad in your tests

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