How to spot counterfeit or second-hand STM32F405RG MCUs?

[Stefan Hamminga]

I designed a board for a client using the STM32F405RGT6. The first batch worked fine, but once the client ordered another batch of boards none of them worked. The used MCU has different markings. A quick image search in Google shows the style of markings on the non-working MCUs are used, but it might be an older style? The difference is mainly in the bottom row layout.

Is there an official guideline for what the correct markings should be and how to detect if an MCU has been used before?

[Stefan Hamminga]

Update: I got some pictures of each MCU type. The newer boards seem to have a revision 2 IC, the older ones a revision 4. The date code seems to indicate the problem MCUs are at least 6 years old?

This is the MCU on the second (later) batch of boards, not working:

 

By comparison this is the MCU on the first batch of boards:

[waclawek.jan]

Let's just assume for start, the mcus in second batch are also OK, but there's some other problem.

Try to be specific in "doesn't work".

Can you program the chips using SWD? If you run some simple trivial blinky, does it run?

JW

[TDK]

The datasheet will have details on marking.

 

The top picture looks more like the marking I've come to expect.