Hi,
Do you know what could be the cause of such an unreliable performance across multiple boards? Maybe some particular heat curve in the reflow process is necessary? Maybe some special layout requirements?
The first place to find those answers is the manufacturer:
They have an internet page for this product:
https://www.st.com/content/st_com/e...ial-eeprom/standard-i2c-eeprom/m24256-df.html
Then scroll down to "Technical Notes & Articles " and find this document: "TN0991: Description of WLCSP for STMicroelectronics EEPROMs and recommendations for use "
Soldering problems depend on so many parameters: Temperature profile, age of devices, solder contents, age of PCB and so on....This makes it difficult to give good assistance.
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"did not work correctly" is no error description.
--> If you need help with this, then you need to provide a detailed error description in a way that a user here can verify your device behaviour with the datasheet or another real circuit.
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I doubt that there are general problems with this device...
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Maybe there are only sodering problems.. but for me it sounds as there are additional issues.
* maybe the power supply is not within specification.
* maybe the communication is not within specification.
* maybe uncontrolled pin states during power up...
We can´t verify this, because you didn´t give enough information...
Klaus