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

Kavi · ‎2026-01-21

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

Andrew Neil · ‎2026-01-21

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.

Kavi · ‎2026-01-21

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 · ‎2026-01-21

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 · ‎2026-01-21

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 · ‎2026-01-21

Well spotted!

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

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.