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Proper routing through a PAD

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  • Proper routing through a PAD

    Hello,
    I found two different routing cases as in the attached image when I working on the 28pin project.
    Sometimes, I found some routing lines on a PAD.
    I am not sure which one is a proper routing through a PAD. Might be both wrong or both right?
    In the lecture video, Robert always double-clicks when routing passes through a PAD and continues the routing.
    but sometimes, I just click to end and restart routing from the PAD.
    My major question is that the isolated line, which is only on a PAD as is shown on the blue arrow is fine or should be removed.



    Attached Files

  • #2
    In my opinion, a trace should continue to the pad center. So the blue one is correct and the green is only half correct.
    The problem is when the end of the trace does not completely cover the pad like in my example:
    Click image for larger version

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    Attached Files

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    • #3
      To Qdrives,
      Thank you for your comments.
      Since the red square is covered by copper, I think two lines of the Green arrow are connected through the PAD.
      In your case, the Gnd line is out of the region. the line is not connected.
      This is my thought. Someone else can clarify these.
      Thank you.

      Comment


      • #4
        Hi Goldchan,

        If you're going to be length tuning, not connecting to the pad centre will through off your values.
        Also, if you need to length tune by propagation delay instead of length, not connecting to the centre of a via will cause Altium to use the total delay of the via instead of the relative delay (tested in AD20 and AD21)

        There are a lot of different ways to route out of a pad, but in your screenshot, the one of the right is the best.


        Kind regards,
        Dan

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        • #5
          To Dan,
          Thank you for indicating the interesting side effects.

          I found somehow I have some routes that do not path through the center of PAD.
          However, this is not visible easily.
          Are there any Altium options to warn this kind of routing? BTW, I didn't receive any warning from my current setting.


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          • #6
            Theoretically you do not need to route into center of the pad (sometimes some software even remove that small tracks inside of pad automatically), however, sometimes this is causing problems. So I would not intentionally route PCBs the way that I would only route until the edge of the pad.

            What kind of possible problems not routing into the center of the pad can cause? Some where already pointed out e.g. measuring length of tracks, not getting full track width at the edge of the pad, but sometimes it can be also like unconnected net, it can be problem when importing your design to software which requires tracks to be connected in center, etc ...

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            • #7
              Thank you for so much information.
              This is a great forum to get very specific information.
              Thanks again for all your kind reply.

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