Experiences with STM32 and XRay or CT

RHaag.1 · ‎2021-02-08

Hello,

during qualification tests, our design with STM32 L4 first went through XRay tests and afterwards even CT to check for soldering problems etc.

XRay was fine, but we have an issue with CT were the controller quit function afterwards. Not even a JTAG/SWD connection!

Of course we are in discussion with our qualification partner, but I'm also interested in general experience here:

Did anybody XRay or CT an STM32 (L4) and face similar problems?

What could be maximum dose (gray) for an STM32?

Thank you!

Regards

Ralph

Uwe Bonnes · ‎2021-02-09

Was the problem on a single sample or a batch of samples?

RHaag.1 · ‎2021-02-09

XRay was done with some ten samples without obvius problems afterwards, but CT testing was done only on a single sample and that failed.

Regards

Ralph

Ozone · ‎2021-02-09

Did you check the Flash contents ?

The smaller the structures get, the more susceptible they are to high energy radiation.

I suppose your difference in X-ray and CT is only in dose (proximity and intensity / field strength).

RHaag.1 · ‎2021-02-09

As we don't even have JTAG access, we could not check the flash until now.

And yes, XRay and CT should in the end only differ in dose. In addition to proximity and intensity, I also would expect time to be higer for CT?!

Regards

Ralph

RHaag.1 · ‎2021-02-15

Update on this issue:

we got the SWD running (I was missinterpreting the tool output, sorry) and were able to readback flash contents.

Some devices show bit flips which should however be "unlikely on normal XRay investigations" according to our service partner.

What else could make a flash bit flip?

Anybody willing to share his experiences on that topic?

Thank you

Ralph