VIA to VIA spacing isn't true in allegro cadence.

Question

I set the VIA to VIA spacing in allegro cadence (v17.2) to 1mil, but allegro not show error in some case. 
 (1)(2) Via pad to VIA pad ovelap ( but VIA drill not overlap) -> Cadence show error -> OK 
 (3) Via pad to VIA pad overlap, and Drill via to Drill via overlap too ( but not all part of Via Drill) -> cadence not show error, not OK 
 (4) Overlapping two VIA ( all part of VIA ) -> cadence show error -> OK. 
 Pls see detailed in attached picture 
 https://drive.google.com/file/d/1tq6xxt0YuE3uD2WyMIXe2cW23tzmv3L4/view?usp=drive_link 
 So, in case (3), is there an issues of allegro cadence?

mcatramb91 · Accepted Answer

Hello, 
 When two same net Vias overlap each other they will generated a DRC until the center of one via crosses over the pad of the other via. At that point the Vias will be considered directly connected.so a DRC Error is not seen. If you want to see a DRC in this situation you will need to change Pad-Pad Connect under Physical to not allow direct connections, NOT_ALLOWED. (Default is set to ALL ALLOWED.) See images below. 
 Hope this helps, Mike Catrambone

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VIA to VIA spacing isn't true in allegro cadence.

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