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Kavi
Associate II
January 21, 2026
Solved

Why are there two holes under the MCU on NUCLEO-G474RE ?

  • January 21, 2026
  • 4 replies
  • 461 views

I noticed two holes at Bottom of the MCU area on the STM32G4 Nucleo board. What is their purpose?stm32 g4.jpeg

    Best answer by Kavi

    yes, now i can understand the purpose.

    thank you :)

    stmcusocket.jpg

    4 replies

    Andrew Neil
    Andrew Neil
    Super User
    January 21, 2026

    I see it also on Nucleo-L476RG (haven't checked further).

     

    I don't know, but I think it might be to facilitate a QFP socket?

    ISTR seeing some early Nucleos with sockets - probably used only internally by ST?

    A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
    K
    KaviAuthor
    Associate II
    January 21, 2026

    I’m developing a custom board for my application, so I need clarification on the purpose of these holes before deciding whether to include them in my PCB.

    Andrew Neil
    Andrew Neil
    Super User
    January 21, 2026

    There is no need to have them on a target board.

    A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
      waclawek.jan
      waclawek.jan
      Super User
      January 21, 2026

      As @Andrew Neil said, it's for a ZIF socket. It's even listed in the BOM 

      HW110Yamaichi socket for LQFP64, with positioning pins.LQFP64YAMAICHIIC149-064-169-B5Not Fitted0

      It's not populated on the boards which are sold to the public, but ST uses them for development internally.

      JW

        Andrew Neil
        Andrew Neil
        Super User
        January 21, 2026

        Well spotted!

         

        @Kavi I suspect that's also what the four solder pads at the corners of the QFP footprint are for:

        AndrewNeil_0-1768999931927.png

         

        A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
          mƎALLEm
          mƎALLEm
          Technical Moderator
          January 21, 2026
          @Andrew Neil wrote:

          @Kavi I suspect that's also what the four solder pads at the corners of the QFP footprint are for:

          AndrewNeil_0-1768999931927.png

           

          I confirm.. these solder pads are used to solder the socket.

          "To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."
            Andrew Neil
            Andrew Neil
            Super User
            February 24, 2026

            Similar here: TFBGA225 Footprint on Discovery/Nucleo - why the holes, etc?

            A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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