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 Tapered Trace function not working 

Last post Thu, Aug 15 2013 7:07 PM by ScottCad. 10 replies.
Started by FrancisFogarty 12 Aug 2013 07:06 AM. Topic has 10 replies and 943 views
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  • Mon, Aug 12 2013 7:06 AM

    Tapered Trace function not working Reply

    Hi Guys,

    im using cadence allegro 16.5 version. and for some reason the tapered trace function wont work on a selected cline?

    i have attached an image with this of the issue and you can see why i wish to taper. the function says it has finished but the cline stays the same.

    i know that there is a desired angle and tapered trace options in the settings for tapered traces but im not sure how this works? would anyone know the optimal settings to get this to work?

    all help is welcome.Thanks

    Regards

    Fran  


    • Post Points: 20
  • Mon, Aug 12 2013 8:25 PM

    • ScottCad
    • Top 50 Contributor
    • Joined on Fri, May 25 2012
    • Roswell, GA
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    Re: Tapered Trace function not working Reply

    Fran the tapered trace function works on two clines of different widths only. No DRC must exist on the net for it to work.

    Try this as a test. Draw a trace with a width of 50 mil for about an inch in length then reduce the trace width down to say 25 mils and continue on routing for about an inch.

    Go to the gloss menu "Route > Gloss > Fillet Parameters.

    Check the option at the bottom of the window "Tapered Traces" I set a desired angle of 60 and a offset of 200, click ok to dismiss the dialog.

    Go back to the route gloss menu and select add a tapered trace. in the find menu make sure cline is checked. Draw a box with your cursor around the point where the 50 mil trace intersects with the 25 mil trace and a little fillet will be put in to taper the trace.

    Hope that helps,

    Quick edit here, Fran in your picture I am not sure if that is a pin that the trace is connected to or not. If it is a pin then you dont need to use the tapered trace option. Just use a fillet instead. Come off the pin with a trace of a suitable size and then gloss it with a fillet. 

    Scott.

    • Post Points: 35
  • Tue, Aug 13 2013 12:59 AM

    • lichao
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    • Joined on Tue, Aug 13 2013
    • Posts 2
    • Points 25
    Re: Tapered Trace function not working Reply

    I am not very clear, maybe you can come here to have a look.

    http://pcb.hqew.net/

    • Post Points: 5
  • Tue, Aug 13 2013 2:18 AM

    Re: Tapered Trace function not working Reply

    Hi Scott,

    yes this is a pin. could you elaborate a bit on how to use the fillet function i have ever used it before. Thanks for the help.

     Regards

    Fran  

    • Post Points: 5
  • Tue, Aug 13 2013 6:58 AM

    Re: Tapered Trace function not working Reply

    Hi Scott,

    i tried using the add fillet but it only trys to correct the point of entry between pad/pin and cline.

    but the extra etch over the pad as indicated by the arrow is the problem. i need this to taper like the pad but it wont work and i dont know what my options are. thanks

    regards

    Fran  


    • Post Points: 5
  • Tue, Aug 13 2013 6:59 AM

    Re: Tapered Trace function not working Reply
    just to be clear i removed the DRC error like you suggested prior to using tapered function.
    • Post Points: 20
  • Tue, Aug 13 2013 12:08 PM

    • ScottCad
    • Top 50 Contributor
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    Re: Tapered Trace function not working Reply

    hi fran,

    I think perhaps the easiest thing to do is extend the pad "Shape" on that pin out further so you can route your trace to it. That would enable you to keep your existing trace width and keep the taper on the pad.

    Would that work ?

    Thanks Scott

    • Post Points: 20
  • Wed, Aug 14 2013 1:27 AM

    Re: Tapered Trace function not working Reply

    Hi Scott, 

    thanks for the reply. i dont want to have to do that because this is an RF SMA launch footprint and is designed as specified by the manufacturers for this board stackup for optimal performace.

    is there any way that i could change the origin of the Pin so that it doesnt snap to the center of the pin? inste4ad it would possibly connect around the leading edge?

    Regards

    Fran  

    • Post Points: 20
  • Wed, Aug 14 2013 10:38 AM

    • ScottCad
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    Re: Tapered Trace function not working Reply

    Fran could you possibly attach the symbol for that footprint ?, I would be glad to take a look at it.

    Thanks Scott

    • Post Points: 20
  • Thu, Aug 15 2013 2:11 AM

    Re: Tapered Trace function not working Reply

    Hi Scott,

    here are the files.

    Regards

    Fran  

    • Post Points: 20
  • Thu, Aug 15 2013 7:07 PM

    • ScottCad
    • Top 50 Contributor
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    Re: Tapered Trace function not working Reply

    Hi Fran, I took a look at your symbol. I think the best way to route a trace to that Tapered center pad is to extend the pad edge out further. so when you route the trace to it you can preserve the taper. I tried a few things and that was the best I could come up with.

    The issue is you more than likely have to use a trace that is a certain width but when you route the trace it is snapping to the center of the pin and because your trace is wider than the tapered pad at that point you get overlap.

    To work around this Extend out the shape before it tapers. You can do this by just drawing another shape to the left of the wide edge of the pad keeping the width the same and then just merge both shapes into 1 shape. This will save you having to move your existing pad.

    when you route your trace to the pad start with a small width to clear the taper then change the width to your required width and it should flow nicely. It will look like a nice tapered transmission line when done. 

    Thanks Scott

    • Post Points: 5
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Started by FrancisFogarty at 12 Aug 2013 07:06 AM. Topic has 10 replies.