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Starved thermal error in the DRC

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  • [Solved] Starved thermal error in the DRC

    Hi all
    I'm following Learn Altium Essentials 2nd ed and I'm stuck at Lesson 4: Doing PCB layout.
    At the end of the lesson there I managed to run the design rule check.
    I've got two errors that I cannot understand.
    Starved thermal on L2: via (21.1mm, 25.3mm) from L1 to L6. Blocked 3 out of 4 entries.
    Starved thermal on L5: via (21.1mm, 25.3mm) from L1 to L6. Blocked 3 out of 4 entries.
    Can anyone please help me?
    Here there is the project:
    Last edited by Lucky-Luka; 12-19-2020, 09:58 AM.

  • #2
    When a pad connects to a large copper element, like a polygon or plane, it can be thermal relieved connection by spokes, or it can be a direct connection. When the connection method is the former, other objects nearby the pad can obstruct formation of some of the spokes. Blocked 3 out of 4 means the pad is only connected by one spoke. 3 cannot be connected because something is in the way.


    • #3
      I see... It is strange because this problem doesn't appear in the video tutorial and I've tried to place the VIAs in the same position as seen in the video. I will try to adjust the position of the VIAs then I'll let you know. Thanks


      • #4
        I have replaced the problematic VIA. Now Altium doesn't give any error. Good! Another question: are the rectangles around the components part of the silkscreen, right? Will they be printed on the PCB surface, right? Can I place my VIAs over those lines as in the attached image? Thanks
        Attached Files


        • #5
          Yes, it looks like the rectangles are silkscreen. You can confirm this by opening the view configuration panel and toggling that layer's visibility.

          Typically, fab shops only print silkscreen over the portion of PCB surface that's covered in solder mask. So you will end up with voids in things on the silkscreen layer where they overlap openings in the solder mask layer.

          If the vias on your design are tented, then they will be covered with solder mask and the silkscreen rectangles will appear continuous. If any of the vias are not tented, there will be an opening in the solder mask over the via which will cause a break in the silkscreen.

          Either way, it should only affect the appearance, not the functionality of the PCB.