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

[Kavi]

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

[Andrew Neil]

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?

[Kavi]

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]

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

[waclawek.jan]

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

HW110

Yamaichi socket for LQFP64, with positioning pins.

LQFP64

YAMAICHI

IC149-064-169-B5

Not Fitted

0

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

JW

[Andrew Neil]

Well spotted!

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

[mƎALLEm]

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@Andrew Neil wrote:

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

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

[Kavi · Accepted solution]

yes, now i can understand the purpose.

thank you :)

[Andrew Neil]

If your issue is now solved, please mark the solution on the post which provided the answer.

[Andrew Neil]

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