Hybrid Cold Plate Technology: Enhancing AI Chip Cooling with 2-Phase Thermal Transition

With the rapid advancement of AI technology, cooling solutions for high-power consumption chips have become increasingly critical. This study explores the development and performance evaluation of hybrid cold plates, combining liquid cooling with two-phase thermal transition technology, providing a significant leap in thermal management efficiency.

Understanding Hybrid Cold Plates

Hybrid cold plates are innovative cooling solutions that integrate liquid cooling with two-phase thermal transition technology. This combination leverages the strengths of both heat pipes and vapor chambers, which are essential components for heat sink design, effectively managing heat through the phase change cycle of evaporation and condensation.

Key Features and Advantages

• Fast Heat Conduction Efficiency: Heat in the vapor state is conducted from the hot end to the cold end at a speed close to that of sound.

• Extreme Heat Transfer Capacity: When the internal liquid's evaporation and condensation cycles reach a perfect balance, theoretically, the cold plate can continuously carry an infinite amount of heat. Achieving this balance is the ideal working state for two-phase flow elements.

Overcoming Technical Challenges in Water Cooling: The Path to Hybrid Cold Plates

In addressing the technical challenges posed by water cooling for high-density CPUs, it became evident that new technological solutions were necessary. After reviewing extensive research literature on CPU water cooling plates, we identified that the performance of these plates is influenced by several key factors:

1. Asource (Heat Source Area)

2. Aplate (Base Plate Area)

3. 入 (Area Ratio Parameter)

4. Ro (Water Cooling Plate Thermal Resistance)

From the heat transfer and fluid flow simulation charts of the computer model, it is clear that these four factors contribute in varying proportions to the overall performance. Among them, the diffusion thermal resistance (Rsp) of the cold plate's base emerged as the most significant area for optimization. This finding indicated that if we could enhance the diffusion characteristics of the base plate, we could effectively address the problem of high heat density.

Development of the Hybrid Cold Plate

Armed with this insight, we embarked on developing a new technological solution that would integrate two-phase thermal transition technology with micro-channel technology. This innovation led to the creation of what we now call the hybrid cold plate.

Drawing from 15 years of experience in heatsink and cold plate development, our team defined a clear specification for this new cold plate. The next step was to design and prototype two versions: one being a traditional micro-channel cold plate, and the other our newly conceptualized hybrid cold plate.

The sample #1-#6 is hybird cold plate which fill with 92%-127% value water and sampel #7 is micro-Channel cold plate.

Performance Evaluation of Hybrid Cold Plates

Once the prototypes were ready, we conducted rigorous performance evaluations to compare the efficiency and effectiveness of these designs.

Flow Resistance Test

Seven cold plate samples were connected to a pump system supplying water at flow rates of 0.8/1.2/1.5 LPM. The flow resistance values were recorded as follows:

The results indicate that all cold plate samples have very similar flow resistance, demonstrating consistency in performance.

Thermal Performance Test

• Testing Conditions:

• Ambient Temperature: 26-28°C

• Liquid: Pure water

• Flow Rate: 1.2 L/min

• Water Inlet Temperature: 28°C

• Dummy Heater Contact Surface: 20x20mm

• Heat Loading: 200/350/500/650 W

Testing result :

The thermal performance testing revealed that the water injection value of the vapor chamber significantly affects the maximum heat transfer capacity (Q-max). For example, sample #3 experienced dry-out at 450W heat loading, while sample #2 dried out at 550W. Samples #4 and #6 demonstrated the best performance with heat loads greater than 300W.

Conclusion

The test results indicate that by fine-tuning the water injection value, the hybrid cold plate can outperform regular micro-channel cold plates in terms of thermal performance. This advancement makes hybrid cold plates a superior option for cooling high-power AI chips.

Winshare Thermal is a professional liquid cooling solution provider. If you need any thermal kits development support, please visit our website or email us at gavin@winsharethermal.com.