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Cpu substrate cooling

as we know there is alot more to cpu cooling then jsut the die. the die and power to the die cause heat on the substrate
image

this is the solder guard off a cpu a i3 7350k
seeing the a video inspired me to think about this more. where after seeing this, cooling made for the cpu substrate starts to make sense the 2 large pads at the top are cpu vcore and igpu power and tend to get hot

video

https://youtu.be/3STf61GIh6Q

using some medium that would allow the heat to transfer from the cpu pcb substrate to the ihs, w/o shorting the cpu would be ideal maybe a thermal pad doughnut (after solder guard is removed) and liquid metal for die.

with cpus getting more and more modular spreading more heat across the pcb maybe its time to switch the pcb substrate and find better thermal materials… ibm played with ceramic substrates before with mild success.

One of the problem with modern dies is the transistors are so small that managing the heat that happens at a nano level becomes difficult when you increase the clocks.

Putting a metal piece on top of the CPU is already a relatively inefficient way to cool it, and an IHS makes this even worse.

Using the PCB to more effectively cool the CPU might be an option, however as you know finding a suitable component that would serve the purpose of being a PCB, and heatspreader would be no easy task.

An interesting thought nonetheless.

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I’m more talking about pcb then CPU is placed on …the CPU is not the target of this discussion… It’s the PCB the die sits on. We can’t really get better at nano thermodynamics. But the rest of the CPU also produces heat and needs a better way to get that heat out plus the CPU die pushes heat into the PCB it sits on …moving that heat is the goal …

Most of the heat in the PCB will be coming from the die itself.
So would it be ideal for the PCB to absorb more of this heat, and then find a method to cool the PCB, or could it be beneficial to have the PCB temperature be less affected by the die?

well thermal mass near the cpu isnt really a good thing …

looking at ibm’s older chips they used ceramics at their cpu pcb substrate which was then soldered to the cpu daughter board which lifted the back of the cpu away to be cooled and the ceramic cpu pcb substrate acted like heat spreader


image there is a thermal pad on the ceramic pcb in this pic

Diamonds and synthetic diamonds don’t conduct electricity and are one of the best conductors of heat in the known universe

But getting a heatsink is expensive, even if it’s just to be an ihs to contact the substrate

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Are you familiar if this is still a viable option with today’s traces?

other then the tooling and drive for such a product… baiscally MOST of us will never use the gained performance of cooling the pcb substrate… it would be better used in data center chips and where penny pinching power and heat would matter

At some point it’s gonna be direct die cooling again for the enthusiasts. Because physics.
Only other thing I could think of would be designing a CPU backplate with heatpipes.

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Actually Delta (faucets) had a piece that was typically made of ceramic made out of diamond for their super premium faucets I don’t know how much of that was marketing but the piece was pretty dang hefty for as small as it was

So if true maybe synthetic diamond expense is purely lack of supply/profit margin

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Related

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@THEkitchenSINK You didn’t link to the video but put the image there a second time. And I can’t write you a message because your profile is set to hidden.

So, here it is:

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thanks i linked the pic twice OOPS

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