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No DRC error when placing or sliding vias over inner traces

greatrace53

Hello, I have been having the weirdest issue lately.  I am working on a 6 layer board with 3 routing layers.  I have a routing layer at the top, a inner layer, and a bottom routing layer.  Currently, when I place a via it will let me place it right on top of on of the inner traces with no DRC.  I first noticed the issue when I randomly spotted a via going thru an inner trace.  I tried to slide the via away and expected the inner trace to 'bubble' around it like normal but it didn't.  I tried to place a new via and it allowed me to do the same thing.  One interesting thing is that if I slide the via right on top of an inner trace, exit the slide command, then initiate the slide again, it bubbles that inner trace out of the way, but if I drag that same via over near any of the other inner traces it acts as if they aren't even there and will let me place the via right on top of them again.  Also, if I go to 'slide' an existing via that is going from top>bottom then back to the top again it will let me place that via on an inner trace and the same issue repeats; however if I 'slide' a via that goes from top>inner or bottom>inner it will 'bubble' the inner traces out of the way like normal.  To my knowledge all of my constraints are set correctly, on-line DRC is on, and none of these are blind/ buried vias.  I have also ran DB doctor but it found no errors.  This is the 4th revision of this board and it has not been an issue at all before this point.  I was able to go back and forth between older revisions of this same board and the 'slide' function was bubbling the inner traces away as it should on the older versions.  Placing a new via right on top of an inner trace caused a DRC error properly as well, but when I returned to my current revision it was still not working properly.  However, for some reason a day later now all of my previous revisions of this board are exhibiting the same behavior.   I am really hoping this is something super simple because this issue has caused a lot of delays on my end.  Any help would be greatly appreciated.  

I am running version 16.6 SO60

  • steve
    It sounds like you have all the relevant checks enabled but you can get on the latest 16.6 hotfix S074 and see if that helps. I would also make sure that if you are using Unused Pad Supression - make sure all the Hole to checks are enabled from Constraint Modes. If it still doesn't help and DBDoctor does nothing you should file this with cadence online support.
  • greatrace53

    Thanks Steve.  I'll download the latest hotfix and see if that helps.

  • greatrace53

    I have updated to 16.6 SO74 and my issue still remains.  I have noticed that my design randomly changed the via padstack to "via1" but even when I changed it to "via' in the constraint manager and tools>replace padstack it still has the same issue.  

  • redwire

    Any way you can zip and post your board or PM it?  It sounds like something is not turned on correctly or a padstack is broken.

  • greatrace53
    Ok so I was reading around on some other posts and decided to turn off 'unused pad suppression' and with that setting off, it would shove and slide the inner traces as normal, but when I turned it back on it went right back to exhibiting the original issue. I have spoken with tech support a few times about this and they were able to open up my board and have the slide function as it should in version 17.2. I think I'm just going to enable the 'hole to' checks in constraint modes and finish the board like that. However it is odd for this function to just stop working properly out of the blue. Thank you for your suggestions everyone.
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