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 Auto-Router Unconnects 

Last post Fri, Aug 21 2009 3:49 PM by hpattie. 1 replies.
Started by PherricOxide 21 Aug 2009 12:35 PM. Topic has 1 replies and 872 views
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  • Fri, Aug 21 2009 12:35 PM

    Auto-Router Unconnects Reply

    I'm attempting to auto-route a fairly large board file in Allegro PCB design/Specctra. Some parts are already routed, but there are at least 3 layers with no etch at all that the auto-router can use, as well as many other layers with only some etch on them. However, when I run the auto-router, I get a large number of "Unconnections", which never seem to route even after hundreds of route and clean passes. I don't understand why this would happen, because if the auto-router will allow clearence conflicts and crosses at the beginning of routing, what would cause some wires to be unconnects throughout the entire process? I can look at the wires and find that most of them are easily routable by hand without moving anything, so why does Specctra find them so difficult?

    • Post Points: 20
  • Fri, Aug 21 2009 3:49 PM

    • hpattie
    • Top 200 Contributor
    • Joined on Thu, Jul 17 2008
    • Posts 43
    • Points 675
    Re: Auto-Router Unconnects Reply

    Without knowing the specifics of your design, this is difficult to answer. some possible answers are;

    net constraints or properties the will not allow routing.

    inability to fanout or via to  another layer.

    net conflict at the component pin.


    Harold Pattie



    • Post Points: 5
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Started by PherricOxide at 21 Aug 2009 12:35 PM. Topic has 1 replies.