
Chip Aging Accelerates - Lind5
https://semiengineering.com/chip-aging-accelerates/
======
squarefoot
Chips aging aside, tin whiskers also are one of the main reasons why
manufacturers shouldn't use electronics except where it is really really
really necessary, especially on things that move at high speeds with humans on
board or in vicinity. NASA itself -which use electronics on stuff that gets in
orbit- did some good research on the subject.
[https://nepp.nasa.gov/Whisker/background/index.htm](https://nepp.nasa.gov/Whisker/background/index.htm)

Tl;dr: Tin whiskers are very thin spontaneous metallic formations which can
short nearby pcb tracks or conductors and are believed to be the cause of many
failures in electronic devices. There is no evidence of a single cause for
their formation but it seems certain that eliminating lead (RoHS legislations
etc.) from solder is one of them.

~~~
Slansitartop
Can't they coat the PCBs to mitigate/elminiate the problem?

I remember watching a teardown of a spare-no-expense embedded military
computer, and the guy couldn't stop talking about how much "conformal coating"
the board had.

Edit: I think this is the video:
[https://www.youtube.com/watch?v=55z_0BYb5is](https://www.youtube.com/watch?v=55z_0BYb5is)

~~~
kurthr
Typically, the coating is Parylene, which is a room temp vapor phase conformal
coating (e.g. roughly uniform thickness independent of the contact angle of
the materials). It's used for corrosion, moisture, vibrational. wear, and
reduced breakdown voltage, etc.

It is not used for Sn (tin) whiskers at all, since it wouldn't penetrate the
pads/package of the IC and wouldn't stop such a high modulus process in any
case. Whiskers are most problematic with modern Pb-free solders and fine pitch
SMT practices (QFNs & BGAs), but it's worth noting that other materials (like
Zn) also have significant issues.

[http://www.paryleneengineering.com/why_use_parylene.htm](http://www.paryleneengineering.com/why_use_parylene.htm)

~~~
LeifCarrotson
From that page:

> The coating completely penetrates spaces as narrow 0.01mm.

I would have thought that would make it very effective in protecting against
whiskers in QFPs that might have a lead pitch of 0.4mm or larger. There's not
a lot you can do under the bodies of BGAs and QFNs, but if you're worried
about whiskers you're probably using QFPs instead.

This app note suggests that Parylene and a few other dip-type conformal
coatings do slow down tin whiskers, but don't stop their spread:

[https://www.maximintegrated.com/en/app-
notes/index.mvp/id/52...](https://www.maximintegrated.com/en/app-
notes/index.mvp/id/5250)

------
ansible
Computing in automotive is a challenge.

In the past, you might have automotive-grade microcontrollers for functions
like ABS, which consume less than a Watt maximum. You paid a little attention
to having enough ground vias on the PCB for thermal conductivity, and that was
about it to qualify the design for the high end of the temperature range.

Degraded lifetime wasn't so much of a concern.

These days, you've got ARM processors with a TDP of 15W or more, and keeping
the die temperatures below the maximum when the ambient temperature is 85C,
well, that starts to get interesting. Especially if you don't want to use a
fan, and the processor is stuck somewhere without adequate airflow.

And then you've got high-end systems with a TDP in the 150W range. Then you've
got to have a good cooling solution to run your application at office
environment temperatures, nevermind the full automotive temperature range. And
what's going to be the lifetime for these parts running at elevated
temperatures, even if you are staying within the maximum temperature limits?
_Sigh_

~~~
Retric
15W chips use ~2% of a HP each, and 150W = 1/5 horsepower worth of parasitic
load. So using several high end chips should result in significantly worse
fuel efficiency.

Are they really necessary or just cheaper in R&D terms?

~~~
simias
Modern cars have tons of advanced features that require a decent amount of
computing. I mean just look at the evolution from radio cassette players to
modern integrated GPS/media player/bluetooth/etc systems. Also things like
automatic parking assist, rear view camera, computer vision algorithms to
detect if the driver is falling asleep. It's feature creep all over the place.

~~~
oblio
> Also things like automatic parking assist, rear view camera, computer vision
> algorithms to detect if the driver is falling asleep. It's feature creep all
> over the place.

You have a weird definition of "feature creep". Some of those things you
listed save money, others save lives. I definitely wouldn't include such
things in "feature creep".

~~~
simias
Sorry, it might not have been the right word. I didn't mean that these
features weren't useful, only that in the past decades the past decades the
amount of software in cars really exploded from basically 0 to having a bunch
of fully featured computers dealing with various subsystems, from fuel
injection to radio playback. Software "creeped" everywhere.

------
IshKebab
> Chips developed for computers and phones lasted an average of two to four
> years of normal use.

Err what?

~~~
kabdib
This is a real thing. For game consoles, which run their chips pretty "hot" in
order to meet the performance requirements for high-end gaming, the main SOCs
have a design lifetime. There are deliberate trade-offs between performance
and the expected lifetime of the part. This lifetime is difficult to estimate
prior to ship.

One console made a firmware update about a year after its release that
increased its clocks by about ten percent. I'm guessing they did this after
seeing telemetry numbers indicating that the box's cooling system was doing a
better job than expected, and that there was lifetime headroom available
(probably other factors were involved, too, but heat is a major one).

~~~
ethbro
I'd be charitable and say that gaming chips run hot because cooling systems
are "optimized", not for performance reasons.

And by optimized, I mean shoehorning the smallest / cheapest solution in there
that barely meets cooling needs.

~~~
kabdib
Consoles are pretty serious about effective cooling. There is definitely price
pressure, but that's not a one-sided thing -- you need to make sure that the
unit lasts long enough, and that its cooling system doesn't generate too much
noise for the environment (typically a quiet living room). And then you need
headroom for envrionmentals (e.g., being stuff into the back of an
entertainment unit next to other equipment). The current generation of
consoles are quiet compared to the last generation, and more powerful.

Cooling "needs" have to take into account the whole product and user
experience, not just keeping a single chip from melting down.

~~~
lione
I think all the console makers learned a lesson from the Red Ring Of Death. No
one wants to be having a massive portion of their systems become useless hunks
of scrap because of poor thermal design not dissipating enough heat and
causing the solder to crack.

~~~
kabdib
RROD cost Microsoft a billion dollars, maybe two billion. That doesn't scream
"Please shave the cooling system down to the absolute minimum cost on the next
console" to the hardware team.

The XBone cooler is a pretty decent one, because the alternative is a ton of
warranty work, plus lawsuits and bad press. And worse, a bad customer
experience.

------
Animats
Two to four year lifespan?

I happen to know that the design life for the Ford EEC IV, the ignition
control system for 1980s Fords, was 30 years. That was achieved; many 30-year
old Fords are still running with the original electronics.

~~~
SemiTom
article says "Chips developed for computers and phones were designed to
operate at peak performance for an average of two to four years of normal use.
After that, functionality began to degrade"

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kingosticks
Enterprise ASICs (i.e. routers) already run at these very hot (and cold)
temperatures on the very latest nodes. They also demand reliability over long
periods - although the consequences of failing to meet that are obviously not
as severe. Ageing is much worse at 7nm but it's already accounted for during
STA. Like everything else, you just assume the worst and it's another chunk of
your clock period you never see. But expecting to run above 125C... not sure
about that.

