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How to control "Same net spacing" constraint rule value of overlap rate?

ichliebedich

Hi All

If I actvate the same net spacing rule at the analysis mode, the same nets between Via and Shape keep the distance per overlap rate.

as I know from the test, the via only applied the rule with same net shape under 50% overlap rate.

but I want to keep short net the via with shape even under 30%. (see below)

of course it is working without activating same net spacing rule, but I have to keep on the rule..

how can I control the rate value of this?

regard

Parents
  • Lock2002

    It uses the exact center of the via or pin. once you cross that it either voids or floods. So you're stuck with 50% 

  • ichliebedich
    in reply to Lock2002

    doesn't it have any function to control the percentage? or is there other alternative way?

  • jc teyssier
    in reply to ichliebedich

    I do not think so: it is not a percentage: if the shape reach the via origin (even if not centered i gues, make no sense in this case)  then it will be connected. If not reaching, it is voided.

    What you have to do is to modify shape boudary to englobe the via (at least via origin)

Reply
  • jc teyssier
    in reply to ichliebedich

    I do not think so: it is not a percentage: if the shape reach the via origin (even if not centered i gues, make no sense in this case)  then it will be connected. If not reaching, it is voided.

    What you have to do is to modify shape boudary to englobe the via (at least via origin)

Children
  • ichliebedich
    in reply to jc teyssier

    thank you I haven't notice that mechanism !  I found alternative way which modify the shape to cover the orgin like below

     

  • jc teyssier
    in reply to ichliebedich

    Be aware that you obtain smalls acid traps at via/shape intersection now.

  • Wild
    in reply to jc teyssier

    I believe there is a misconception in the industry about acid traps.  Experts such as Lee Richey have been stating that Acid Traps have not been an issue since the early 2000's.  I would recommend a conversation with you fab house to double check this.

    See here for an article on this and the 90 degree bends (Taken from "Right the first time" - great read), Speeding Edge.  I also believe I have seen this topic discussed in Dr. Howard's tutorials.

    More info here: https://resources.altium.com/p/slaying-900-right-angle-bend-dragon

    I know it's an altium_crap site, but good information can also come from the "dark side: Slight smile

  • jc teyssier
    in reply to Wild

    Well, some of my design have required/expected life more than 30 year in uncontroled environment. Some of them are for security. I can not have a  risk with acid still eating copper. And avoideing acid traps is verry easy.

  • Wild
    in reply to jc teyssier

    When I stared my carer at Bell Labs in 1986, we saw issues with acid traps, so I am not denying that this was a problem.  However in the late 190's - early 2000's the manufacturers that (Lucent Power Systems) we used never had issues.  This was alluded to in the articles I referenced.  I am not saying that it is not good practice to avoid the sharp corners, but rather I suggest that users talk with their fab house and not blindly follow rules that may not be an issue.  Did you read the article?

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