HTOL failure mechanisms

Guest

Hi,
What are the most common failure mechanisms associated with HTOL test on a packaged die (85C/3.3V)? Can they be related in any way to a retaind humidity in the package that "reveals" itself after 1000 hours? If the failure arises from an entrapment of humidity- can it be contained by dry baking of the package prior to stressing? And if so, why would it fail under high temp. after all?

Joined: 20 Jun 2026 Posts: 76

Hi Rel Gal,

I'm not sure if I understand your question correctly, but the usual fmechs associated with HTOL are TDDB, electromigration, and mobile ionic contam. I think you need to do FA on your failures to know the fmech, then we can decide if it's related to the HTOL you performed or not. Keep us posted. By the way, what's the package?

FARel Engr

Guest

Hi,
Thnxs for your prompt reply.
The package is CSP.
We are not familiar with package related HTOL failures with our package, and after xsectioning there is nothing we observe that can be attributed to the package.
I figured if the failure HAS to be associated with the package then maybe it is retained humidity...
aren't all of the other failure mechs. you've mentioned mostly associated with DIE failure rather then package?

Joined: 20 Jun 2026 Posts: 76

Hi Rel Gal,

All the fmechs mentioned are die-related because HTOL is basically a device-related rel test (not package-related). In fact, many companies don't do HTOL anymore if they are doing a purely package-related qual.

I don't think your failure is due to moisture, because HTOL is supposed to get rid of moisture. I am inclined to believe that you are getting failures that are NOT related to the package - maybe ESD-induced or real die-related failures that you can no longer find.

What is your failure rate? If you only got one marginal failure and you can't find any package defect, then it's probably safe to assume that your package qual is ok. Good luck!

FARel Engr

Guest

failures after 1000 hrs could also be the end-of-life of the device.

Joined: 20 Jun 2026 Posts: 76

Good point, Bago... That's indeed the most possible scenario here. Rel gal just needs to be ready if someone (the customer?) brings up the point that there's also a little possibility that the failures actually occurred immediately after the last read point (500-H?), in which case it's not yet end-of-life.