8 ms·
Unfortunately, most of the useful data you want about wearout is locked behind tech NDAs so nobody will be able to offer specifics here. But in general, the wa
by sweetjuly 3y ago
Unfortunately, most of the useful data you want about wearout is locked behind tech NDAs so nobody will be able to offer specifics here.
But in general, the way you tend to end up with wearout is through electron migration ("electron wind") which is damage to interconnects from electrons slamming into metal atoms over and over and slowly ripping apart the wires. Modeling electron migration correctly is really hard, but (from memory) a general relationship is that voltage linearly increases failure rate and temperature exponentially increases it. The constants for these models are determined empirically and, of course, are NDA'd.
In general, I wouldn't worry about it. The MTTF for semiconductors is already very high even under awful temperatures 100+ C, and so as long as you cool it properly you'll be fine.
> would it be expected that a non-zero amount would fail?
The failures you describe here are going to be due to setup time violations. These issues shouldn't be transient (assuming identical temperature and voltage) since the performance characteristics of an individual device don't really change over time. Of course, the issues can seem transient as the failures may not actually always cause noticeable corruption (maybe you generate a wrong FPU result but that specific path is only exercised under rare uarch conditions).
So, it's a non-answer, but: yes and no. Maybe your chip is perfectly okay and never has any violations at the parameters you selected. Maybe it does. Neither you (nor in fact the manufacturer, though they do have a better chance since they know the process/design) can ever really be sure--all that's left is empirical burn in testing and hoping for the best :)
- magicalhippo 3y agoI can't find the references right now, but I recall reading that longevity of microcontrollers and similar could also be somewhat accurately modeled by the Arrhenius equation[1], meaning a 10C increase in operating temperature would result in roughly half the expected lifetime. [1]: https://en.wikipedia.org/wiki/Arrhenius_equation https://en.wikipedia.org/wiki/Arrhenius_equation
- sweetjuly 3y agoI believe you might be thinking of Black's equation? [1]. It's one equation which attempts to model the failure rate due to electron migration. It isn't a physical model but it seems to, with the right constants, fit reasonably well. The 10C=>halving life time is going to depend on the constants though. [1] https://en.wikipedia.org/wiki/Black's_equation https://en.wikipedia.org/wiki/Black's_equation
- magicalhippo 3y agoAh, must be. Though it wasn't mentioned by name in the source[1] I found earlier the equation seems to match. Instead they attribute it to Arrhenius, but I guess Black's equation is a special case. [1]: https://www.ti.com/lit/an/snva509a/snva509a.pdf https://www.ti.com/lit/an/snva509a/snva509a.pdf