The Technological Foundations of a Cooling Revolution

Driven by artificial intelligence (AI), big data, and cloud computing, global computing power demand has surged exponentially, with server power density skyrocketing from 20 kW per rack to over 100 kW per rack. Traditional air cooling technologies, plagued by inefficiencies and high energy consumption, are gradually being phased out. Liquid cooling, with its superior heat dissipation, low energy consumption, and high-density deployment capabilities, has emerged as the core solution for next-generation data centers. The synergy between liquid cooling brazing processes, liquid cooling plate designs, and server architectures is reshaping the fundamental infrastructure of computing power.

1. Liquid Cooling Brazing: The "Welding Revolution" in Precision Manufacturing

As the cornerstone of liquid cooling systems, liquid cooling plates demand manufacturing processes that ensure both efficiency and reliability. Vacuum brazing, with its design flexibility and welding precision, has become the dominant technology for aluminum alloy liquid cooling plates.

1.1 Principles and Advantages of Vacuum Brazing

Vacuum brazing involves heating base metals and filler materials in a vacuum environment, leveraging the wetting, spreading, and capillary action of molten filler to achieve oxidation-free, high-precision joints. Its key advantages include:

• Oxidation-Free Environment: The vacuum removes surface oxide layers from base metals, eliminating flux residue-induced corrosion and enhancing product durability.

• Complex Structure Adaptability: The excellent fluidity of filler materials enables filling of micron-level gaps, supporting highly customized flow channel designs for maximum heat dissipation efficiency.

• High Production Efficiency: Multi-component stacking in a single furnace run boosts productivity by over 30% while minimizing thermal deformation and ensuring plate flatness.

1.2 Filler Material Innovation and Process Challenges

The dense aluminum oxide layer (Al₂O₃) on aluminum surfaces poses a major challenge for brazing. Current mainstream filler materials are based on the Al-Si system (7%–12% Si), with eutectic composition (11.7% Si) offering a melting point of 577°C, suitable for high-melting-point alloys like 3A21. By adding magnesium (Mg), low-melting-point Al-Si-Mg alloys can disrupt oxide layer bonding, improving wetting. However, filler composition is highly sensitive to process parameters—even minor deviations can reduce joint strength by over 30%, necessitating empirical data-driven optimization.

2. Liquid Cooling Plates: The "Microchannel Revolution" in Heat Dissipation

Liquid cooling plates transfer heat from components (e.g., CPUs, GPUs) to coolant via internal microchannels. Three key trends define their evolution:

2.1 Structural Innovations: From Blown to 3D-Printed

• Blown Liquid Cooling Plates: Formed by inflating aluminum sheets with high-pressure gas, these plates offer low cost but limited flow channel precision, suitable for mid-to-low power applications.

• Brazed Liquid Cooling Plates: Using vacuum brazing, these plates support complex designs (e.g., spiral, fractal tree channels), boosting heat dissipation efficiency by over 40% and becoming the industry standard.

• 3D-Printed Liquid Cooling Plates: Selective laser melting (SLM) enables micron-level control over channel cross-sections, though high costs currently limit adoption to high-end supercomputing.

2.2 Material Upgrades: From Aluminum to Copper-Titanium Alloys

While aluminum dominates due to its lightweight properties and corrosion resistance, copper-titanium alloys are gaining traction in high-power scenarios for their superior thermal conductivity (copper: 401 W/m·K) and corrosion resistance. For instance, NVIDIA’s GB300 servers increased cold plate usage from 45 to 108 units per rack, with copper-titanium alloys accounting for over 60% of the total, enabling power densities exceeding 100 kW per rack.

3. Server Architectures: System-Level Integration of Liquid Cooling

The widespread adoption of liquid cooling requires seamless integration with server motherboards, power supplies, and memory modules. Cold plate liquid cooling, cold immersion, and spray cooling are the primary approaches, with cold plate systems dominating 95% of the market.

3.1 Cold Plate Liquid Cooling: The "Golden Balance" of Indirect Cooling

• Working Principle: Cold plates adhere to CPUs/GPUs, with coolant circulating through internal channels and connecting to external systems via quick-connect fittings.

• Advantages: Low retrofitting costs (replacing air heat sinks only), compatibility with existing air-cooled architectures, and support for "hybrid air-liquid" modes for mid-to-low power components.

• Case Study: Inspur Information’s all-liquid-cooled rack supports NVIDIA H100 GPU cooling, reducing Power Usage Effectiveness (PUE) from 1.6 to 1.05 and saving over 1 million kWh annually.

3.2 Immersion Liquid Cooling: The "Ultimate Solution" for Direct Cooling

• Working Principle: Servers are fully submerged in fluorinated liquids (e.g., 3M Novec), using boiling or convection for heat dissipation.

• Advantages: PUE as low as 1.03, power densities up to 750 kW per rack, ideal for supercomputing and AI training clusters.

• Challenges: Requires server redesigns (e.g., removing fans) and higher initial costs, though total cost of ownership (TCO) is 35% lower than air cooling over the lifecycle.

• Case Study: Sugon deployed the world’s largest immersion cooling project (over 5,000 nodes), supporting high-density computing for Tencent, ByteDance, and other clients.

4. Industrial Chain Collaboration: From Components to Ecosystem-Wide Breakthroughs

The liquid cooling server ecosystem relies on cross-sector innovation:

• Upstream Components: Localization rates for liquid cooling plates, quick-connect fittings, and coolants exceed 70%, though high-end fluorinated liquids still depend on imports (e.g., 3M Novec). Juhua Group achieved 99.999% purity in self-developed coolants, cutting costs by 40%.

• Midstream Manufacturing: Inspur Information and Sugon lead in full-stack liquid cooling technologies, with annual production capacities exceeding 100,000 units across cold plate and immersion systems.

• Downstream Adoption: Finance, internet, and telecom sectors account for over 70% of demand, with liquid cooling penetration surging from 15% to 30% after H20 chip approvals.

5. Future Outlook: Three Key Trends in Liquid Cooling

1. Two-Phase Cooling Adoption: Phase-change immersion cooling, leveraging liquid boiling for 30% higher efficiency than single-phase systems, is projected to capture over 40% market share by 2027.

2. Edge Liquid Cooling Boom: Compact, modular liquid cooling solutions will deploy in 5G base stations and industrial IoT, enabling "last-mile" computing power delivery.

3. AI-Driven Intelligent Temperature Control: Machine learning will dynamically adjust flow rates and temperatures to match workload fluctuations, optimizing real-time PUE.

Under the dual imperatives of carbon neutrality and computing power demand, liquid cooling has transitioned from a "nice-to-have" to a "must-have" for data center upgrades. From brazing process breakthroughs to server architecture integration, Chinese firms now dominate the global liquid cooling market, with the sector expected to surpass $17 billion (RMB 120 billion) by 2025. This cooling revolution not only resolves high-power heat dissipation challenges but also, through unparalleled energy efficiency, paves the way for AI, metaverse, and other future technologies.