The first rule of liquid cooling is 'Don't wet the chip.' Microsoft disagrees
- Reference: 1758696110
- News link: https://www.theregister.co.uk/2025/09/24/microsoft_microfluidics/
- Source link:
As explained in a Tuesday [1]post , the technique is called “Microfluidics” and sees “Tiny channels … etched directly on the back of the silicon chip, creating grooves that allow cooling liquid to flow directly onto the chip and more efficiently remove heat.”
Microsoft says each groove is “similar in size to human hair”, and that it placed them after analysis – helped by AI, because 2025 – to determine which parts of a chip need cooling. The result is a matrix of grooves that the software giant says “resembles the veins in a leaf or a butterfly wing – nature has proven adept at finding the most efficient routes to distribute what’s needed.”
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The software giant says the channels that carry the liquid coolant “are deep enough to circulate adequate cooling liquid without clogging while not being so deep as to weaken the silicon such that it risks breaking.”
[3]
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Here’s a look at a chip that uses microfluidics.
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Channels on a chip that funnel coolant using microfluidics. Photo by Dan DeLong for Microsoft. - Click to enlarge
The post says Microsoft staged “lab-scale tests” in which it found microfluidics “performed up to three times better than cold plates at removing heat, depending on workloads and configurations involved” and “reduced the maximum temperature rise of the silicon inside a GPU by 65 percent.” It is unclear what the latter metric means.
[6]If you dip your toes into immersion cooling, watch out for dielectric liquid sharks
[7]Hyperconverged infrastructure is so hot right now it needs liquid cooling
[8]Euro cloud biz trials 'server blades in a cold box' system
[9]AI ambition is pushing copper to its breaking point
Microsoft didn’t offer any details about the liquid coolants used so we don’t know if they’re practical or safe to use in datacenters other than Microsoft’s hyperscale facilities. The company did allow that its microfluidics rig needs a leak-proof package.
The software giant’s post posits microfluidics could one day see 3D chip designs in which liquids flow through large semiconductors and imagines the tech could one day deliver denser and more efficient datacenters.
But the post is also a blue-sky affair devoid of commitments to implement microfluidics, leaving conventional methods like cold plates and immersion in dielectric liquids the safest liquid cooling options. ®
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[1] https://news.microsoft.com/source/features/innovation/microfluidics-liquid-cooling-ai-chips/
[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/systems&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2aNPBNAvpKGU-r-lMPx7SfwAAA0o&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/systems&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aNPBNAvpKGU-r-lMPx7SfwAAA0o&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/systems&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33aNPBNAvpKGU-r-lMPx7SfwAAA0o&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[5] https://regmedia.co.uk/2025/09/24/supplied_microsoft_microfluidics.jpg
[6] https://www.theregister.com/2025/02/25/immersion_cooling_dielectric_liquid_market_concentration/
[7] https://www.theregister.com/2025/04/24/lenovo_hci_liquid_cooled/
[8] https://www.theregister.com/2025/02/20/diggers_exoscale_liquid_cooling/
[9] https://www.theregister.com/2024/11/28/ai_copper_cables_limits/
[10] https://whitepapers.theregister.com/
Re: Similar in size to a human hair you say?
Not even practical with water - silicon + water + heat + metals + voltage = a certain recipe for corrosion. (And given the atomic scales of modern chip structures only a very tiny amount of corrosion would be enough to disable a chip.)
A liquid other than water would be needed - something that can not react with silicon (or any other constituent of a chip) is needed.
Re: Similar in size to a human hair you say?
I can't see how the flow rate will be enough to have any real effect. Viscosity has a greater relative effect at small scales. Are they using liquid helium?
Could be nice, but...
This would be really cool, but as noted would require super pure water.
And MS research has been really eager to come out with super important sounding papers that are complete bunk, like their majorana qubit stuff for quantum computing.
So until they can actually show this working with real chips on real problems it's best just to treat it as a chest beating press release and not expect too much.
denser and more efficient datacenters
What exactly is being put into these dense and efficient datacenters? Might it not be more efficient in terms of power and cooling requirements simply not to put so much stuff in there? How much is really needed?
Liquid Cooling is a Great Idea
Right up to the time when it's not.
Not water...
I doubt they'd use water in this scenario, no matter how pure, as it's physical properties would cas serious problems. Water is an electrically polarised molecule which means it has:
Strong cohesion and adhesion leading to high surface tension and capillary attraction. Once it's in the microtubes, good luck getting it out again.
Solvent properties. It can dissolve so many ionic & polar substances, it's known as "the universal solvent"
Low solid density. If it ever freezes in the microtubes (e.g during transport), it'll explode the chips - see https://youtu.be/YpQwQx2lMGk
I think they'd use a far more inert fluid for this job.
Re: Not water...
If it ever freezes in the microtubes (e.g during transport), it'll explode the chips
If the water pump stutters or fails the water might boil and explode the chips.
So it's basically capillaries? No mention of flow rate, would have to be a hell of a balancing act.
qualified like this?
They etch grooves in the backside of the wafer. Assemble the die with holes in the package(aligned to the grooves).
I hope the device/package was qualified like this. A lot of quality work is trying to invade through the device legs and package interface.
If the liquid passing through the backside silicon can get to the top side I'd be worried.
Show the qual data.
Why not just drop the whole thing in non-conductive oil. Thought this had been done many times already and it was just the maintenance ballache the stopped it being viable
Similar in size to a human hair you say?
I wonder how they'll prevent deposits from the water clogging up the channels. I reckon this requires very pure coolant, i.e. no microorganisms or minerals at all. They can't exactly shut down and drain the loops, so they'll need a filtration system to keep it that way.
This is relevant to any kind of liquid cooling solution, but having channels this thin sounds like a nightmare.