Reply 100 of 166, by BitWrangler
the3dfxdude wrote on 2022-01-24, 18:20:
It is a problem in design at advanced nodes right now. Sometimes the design teams do model the lifetime due to aging, heat and electromigration out to 10 years. I'm not sure if I've really seen 20 years, I'd guess they'd have to severely under budget performance for more life span. Frankly, in the consumer space, I doubt they really care once it's out of warranty. But they do for critical systems like car and aerospace, so they might be hardened against it some. But any modeling here is definitely a guess. I think 3nm is going to be a problem, where some are pushing to get better models done now. I can't remember exactly, but a few years ago, I was hearing some numbers that led me to guess the actual estimated lifespan of some of the high performance stuff is probably 7 years, and that is with redundancy built in. I started telling people to buy the lower performance, low power variants if you want stuff that last a long time, but even then they cut corners there too, or maybe they are the poor silicon versions of the higher performance part anyway 🙁 So coupled with packaging & integration that is hard to deal with for the average person for repair, I do not trust current stuff to be made to be around as long.
Yes, on 486 dice we only have to worry about several millions of charge carriers diffusing into the substrate further away than 5V can push across the junction. In advanced and future nodes, it's more worrying about a few dozen migrating further away than 0.5V can push. In the former case, there's much more "averaging" of bulk behaviour happening, in the latter case, it's much more prone to disruption by statistical oddities... i.e. they all flip heads, instead of about half heads, half tails. Then your bathtub failure curve is looking like a V. This shorter lifespan doesn't really make anything cheaper, since now they're pricing in warranty replacement costs for the one in 20, maybe one in 10 CPUs that will have really athletic charge carriers, just sprinting away from those junctions.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.