Cooling a processor chip

[sophiecentaur]

I have been idly browsing what Apple have to offer with their new iPhone17. There is mention of 'Vapour cooling' to deal with the heat generated. Would that be the same sort of idea that was used in 'Heat Pipes' where water evaporated at the processor end and liquid water was returned from the cool end and back along a wick.

At the extreme high power end, Vapour Phase Cooling has been used in multi-kW RF transmitters where (pure) water was pumped to the Anode / or alternative Collector and the vapour passed through a cooling matrix.

The idea of that going on in my pocket is strangely exciting. But so many other features are pretty impressive. But I do wish the iPhone processor could be slowed down to avoid my leg getting burned when the phone is thinking too hard. 'Won't change, rather than' can't change, I suspect.

 

[256bits]

same sort of idea that was used in 'Heat Pipes

I would think so,
The case is the cool heat radiator.

 

[Baluncore]

If the fluid is pure water, then the capillaries that wick the liquid water back to the hot end, will need to survive ice wedging when freezing, and the enclosure will also need to be chemically non-reactive with water. In heat pipes that are exposed to freezing conditions, propylene glycol, or a simple alcohol, is added to water as an antifreeze.

 

[sophiecentaur]

@Baluncore I’m not sure about the electrical insulation of a mixture with antifreeze. Vapour phase cooling in a big transmitter would probably not suffer from icing. Two cooling loops would solve the problem.
It looks like some heat pipe systems may use non-pure water (if other factors don’t arise).

Do you have any knowledge regarding my iPhone query?

 

[FactChecker]

Does the iPhone 17 processor really get that hot? There are liquid coolers for desktop PC processors. I don't know the details of how they work. This recent test might interest you.

 

[256bits]

Inside the smart phone there is little room for convection nor radiative cooling. The last option, conduction, can be split as being either passive or active. The passive can use the circuit board or a specialized heat conductive sheet(for such a thin space) to remove the heat from the components. For the i17, an active was chosen by Apple.
If the heat from a components is not removed, its temperature will increase, and if unlucky, to a point where the component will throttle, shut down or completely fail. By adding passive or active heat removal, one is more 'sure' that the equipment ( i17) will meet expectations of user satisfaction.
Such is the reason for such tech details in the user guide where its states operating ambient temperature conditions between such and such temperatures. The active should allow usage in more extreme and prolonged higher ambient temperature conditions.

Perhaps Apple was getting complaints of product failures, and decided to up their game.

 

[sophiecentaur]

Does the iPhone 17 processor really get that hot?

Not a straightforward question, in fact. Years ago, someone made the point, to me that what counts is not the surface temperature of the package but the temperature of the chip. Just like with electrical resistive chains, the overall temperature drop will be the sum of the ΔT steps on the way out. Merely increasing the heat transfer capability of the cooling system can make the surface temperature of the package as low as you want but the chip itself will get hotter and can exceed the safe value.

The liquid coolers quoted by @FactChecker can allow you to over-cook a processor chip and the original makers of the computers cannot be held responsible. Neither can the kit supplier because they'll put suitable warnings on the box. Boy racers will always take risks; fair enough.

satisfy user satisfaction

But, as with smokers and heavy drinkers, the consumer can be 'satisfied' at the same time as doing damage. Advertising can be responsible for this. The fate of the processor is up to the way the owner treats it. I have no interest in 'clocking' my computers nor in extra cooling systems. My question was about how Apple do it in their latest phones.

I will repeat my supplementary question, made earlier, about the possibility of slowing processor speed to reduce dissipation. They already have a low power mode when the battery is low so the principle is already established.

 

[256bits]

I will repeat my supplementary question, made earlier, about the possibility of slowing processor speed to reduce dissipation. They already have a low power mode when the battery is low so the principle is already established.

What happens in low power mode to extend battery energy besides the screen going dimmer?
Do certain apps become non-operable?
Wifi is power hungry as is video, either watching a cat tik-tok, or recording someone's belly flop into a pool.
Throttling the cpu would mean less data throughput, so something has to compensate somewhere.

These could be possibilities with throttlng, paying attention to the above examples:
The car video either becomes jumpy, or of a lessor resolution, lessening user satisfaction.
Same for the belly-flop recording, and playback is of a lessor quality disappointing the user.
The user gruntles about paying a $1000 for the i17; he/she might as well have stayed with the previous model.

I guess hot phones are a problem, as PcMag wrote this:
https://www.pcmag.com/how-to/what-to-do-if-your-phone-is-overheating
They say (looking at you, Galaxy Note 7 and iPhone 15 Pro).

 

[sophiecentaur]

What happens in low power mode to extend battery energy besides the screen going dimmer?

I only quoted that to make a point that users are prepared to accept reduced performance when they need to (in this case, to extend battery life.

Each time a logic element changes state, a tiny amount of charge flows. A circuit with millions of elements, running at GHz frequencies will take significant power, even with pF capacitances involved. The clock rate will therefore govern the rate of battery consumption and (P = IV) the power dissipation. Generations of logic have achieved lower battery drain (and cooler operation) by lowering the Vcc. Lower logic voltages means worse interference between units so design needs to take this into account. It affects all levels of use; phones can last longer between charges when the supply volts are lower and Switching Centres, which consume breath-taking amounts of energy could save energy by lowering supply volts (but this introduces other problems)