Background of Microchannel Cooling Technology: NVIDIA’s high-performance chips (such as H100, B200) consume over 700 watts during AI training and inference, and traditional air cooling or conventional water cooling can no longer meet their thermal management needs.
Microchannel cooling integrates micron-scale channels within the packaging or heat dissipation structure, allowing coolant to approach the chip’s core heat sources closely, significantly reducing thermal resistance and increasing heat flux handling capability. Compared to traditional solutions, microchannel cooling can more efficiently remove heat and ensure stable operation of chips under high loads. It is an important method for addressing thermal management challenges in the era of high-density computing.
01
Why use microchannel cooling?
Integrated circuits, especially high-performance CPUs, GPUs, AI accelerators, and ASICs, have extremely high power density (W/mm²). Traditional air cooling, heat pipes, and even conventional water cooling are nearing their limits.
Root of the problem:
Heat is generated in specific hot spots on the silicon die, but the heat dissipation path is long (chip → package → TIM → heatsink → air/water).
Each interface layer (e.g., TIM, solder, packaging material) adds thermal resistance, increasing the chip’s temperature.
Simply increasing the water block size or adding fans has limited effect, especially with cooling demands over 1kW, where traditional solutions fall short.
Hence, microchannel cooling was proposed — the core idea is:
Bring coolant as close to the heat source as possible by etching micron-scale cooling channels directly into the chip or packaging, allowing liquid to flow through the microchannels and directly carry away heat.
02
What is the structure of microchannel cooling?
It can be understood as follows:
On the top of the chip or packaging lid, a series of channels with widths and depths ranging from tens to hundreds of microns are created (imagine a very fine “waterway” network).
Coolant (water, cooling oil, or even fluorinated liquids) flows through these microchannels, directly flushing the hot regions.
A metal cover (commonly copper or stainless steel) seals the top of the microchannels, forming a closed “cold plate.”
The coolant connects directly to the external circulation system through inlets and outlets, enabling efficient heat exchange.
In comparison: traditional water cooling winds tubes around a heatsink, while microchannel cooling places the “tube” directly on the chip surface, drastically shortening the distance between heat source and coolant.
03
Why is it efficient?
Key points: shortened heat conduction path + increased heat exchange surface area.
Short path: In traditional structures, heat passes through the silicon die, TIM, IHS (lid), thermal paste/solder, and cold plate — all adding thermal resistance. Microchannels place the coolant directly on the chip or package, reducing intermediate layers.
Large surface area: Microchannels can be designed very densely (e.g., 100 channels in parallel), giving the liquid far more contact area than traditional flat heat exchangers, enhancing convective heat transfer.
High flow velocity: The narrow channels increase the Reynolds number during liquid flow, promoting turbulent heat transfer.
Experimental data shows that traditional cold plate heat transfer coefficients are in the thousands of W/(m²·K), while microchannels can reach tens of thousands or more.
04
Capable of “two-phase cooling” (liquid-gas coexistence)
If only using sensible heat (liquid warming), the heat absorption capacity per unit volume is limited.
For example, heating water from 20℃ to 80℃ absorbs about 250 kJ/kg;
But if the water boils in the channel (two-phase cooling), the vaporization latent heat is about 2250 kJ/kg — roughly 7 times more heat absorption.
That’s why many studies combine microchannel cooling with phase change (boiling cooling), allowing partial vaporization inside the channel to greatly enhance heat dissipation capacity.
Challenges:
How to control the location and size of bubble formation to avoid channel blockage?
How to design appropriate flow rate and pressure to prevent local dry-out?
How to ensure long-term system reliability (anti-corrosion, anti-deposition)?
05
Practical Applications and Challenges
Application areas:
High-performance CPUs/GPUs: Intel’s experimental prototypes have integrated microchannel cooling into the package, with cooling capabilities exceeding 1kW.
AI chips/ASICs: Data center-grade chips have extremely high cooling demands that traditional liquid cooling cannot meet; microchannel is a popular solution.
Power devices: Such as IGBTs, lasers, and RF amplifiers are also adopting microchannel designs.
Engineering challenges:
Complex manufacturing: Microchannels require precision etching or micromachining, which must be cost-effective and yield-controlled.
Liquid sealing and reliability: Microchannels are narrow, so clogging and leakage risks are high.
Difficult maintenance: Once blocked or corroded, the channels are hard to repair.
System integration: Requires pump, tubing, and coolant management to be integrated into the overall system design.
06
One-sentence summary
Microchannel cooling places “coolant pipes” as close to the chip as possible, using micron-scale channels to greatly enhance heat transfer, and even introducing boiling heat transfer to achieve higher thermal limits.
It enables high-performance chips to remain stable under extreme power loads but demands high levels of design and manufacturing, requiring multidisciplinary collaboration in packaging, fluid dynamics, and materials.
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