I have made my custom boards inspired from nucleo board l073 but i cannot reach the same power specifications as the nucleo board. Indeed, with the same firmware, on the nucleo board, i consume 3uA whereas on my custom board i'm around 30 uA. I have also noticed when i put and push with my finger the stm32, current consumption increases or decreases ... So, i'm suspecting my solder paste that is a cheap chinese one Sn63 Pb37.
If you have any ideas of how nucleo boards are made, feel free to share
Thank you very much.