Why is the low impurity content of liquid-cooling oxygen-free copper crucial to the heat transfer efficiency of high-performance liquid cooling systems?
Publish Time: 2026-02-05
In today's era of rapid development in artificial intelligence, high-performance computing, and data centers, chip power consumption continues to rise. The heat density of a single GPU or CPU has exceeded 500W or even 1kW, making traditional air-cooling systems unsustainable. Liquid cooling technology, with its high heat capacity and direct contact cooling advantages, has become the mainstream solution for high-end heat dissipation. As the "highway" for heat transfer in liquid cooling systems, liquid-cooling oxygen-free copper, due to its extremely low impurity content, has become a core material for manufacturing cold plates, liquid cooling pipes, and thermal busbars. Its high purity not only affects thermal conductivity but also directly impacts the long-term reliability and energy efficiency of the system.1. Impurities are "invisible obstacles" to heat transferLiquid cooling oxygen-free copper The thermal conductivity of metals mainly relies on the directional movement of free electrons. In copper crystals, the more complete the lattice and the fewer defects, the lower the resistance to electron migration and the higher the thermal conductivity. Although ordinary industrial pure copper contains 99.9% copper, it still contains trace impurities such as oxygen, sulfur, iron, and lead. These impurity atoms disrupt the periodicity of the crystal lattice, forming scattering centers and significantly hindering electron movement. Oxygen, in particular, readily reacts with copper to form Cu₂O inclusions, which not only reduce electrical and thermal conductivity but also induce "hydrogen embrittlement" at high temperatures—when the system uses a hydrogen-containing cooling medium or is in a reducing atmosphere, hydrogen permeates and reacts with cuprous oxide to generate water vapor, leading to internal microcracks.2. High Thermal Conductivity = Low Thermal Resistance = Low-Temperature Chip OperationIn liquid-cooled cold plates, heat is transferred from the chip to the copper substrate via the interface material, and then carried away by the coolant through internal channels. Throughout this process, the thermal conductivity of the copper material determines the lateral heat diffusion efficiency. If the thermal conductivity is insufficient, heat will accumulate locally, forming "hot spots," forcing the system to reduce its frequency for safety. Oxygen-free copper, with its ultra-high thermal conductivity, can quickly and evenly distribute concentrated heat sources across the entire surface of the cold plate, maximizing the heat exchange area with the coolant, thereby significantly reducing the chip junction temperature. Experiments show that, under the same flow rate and temperature difference conditions, oxygen-free copper cold plates can reduce thermal resistance by 3–8°C compared to ordinary copper cold plates, which is crucial for maintaining the long-term full-load operation of AI chips.3. Low Impurities Enhance Corrosion Resistance and Long-Term StabilityLiquid cooling oxygen-free copper systems often use deionized water, ethylene glycol mixtures, or fluorinated liquids as cooling media. Although treated, these may still contain trace amounts of ions or dissolved oxygen. Impurities in ordinary copper can form micro-galvanic corrosion cells, accelerating localized pitting or flow corrosion. Oxygen-free copper, due to its pure composition, uniform structure, and consistent electrochemical activity, greatly inhibits electrochemical corrosion. Combined with surface passivation treatment, a dense organic protective layer can be formed on the copper surface, further isolating it from corrosive media. This extends the lifespan of liquid cooling systems to over 10 years, preventing damage to expensive equipment due to pipe perforation or cold plate leakage.4. Guaranteed Machining Performance and Structural IntegrityHigh-purity oxygen-free copper also possesses excellent ductility and weldability, making it suitable for precision machining into microchannel cold plates or complex three-dimensional flow channels. Low impurity content reduces the precipitation of brittle phases during hot working, preventing cracks or porosity during bending, stamping, or brazing, and ensuring the sealing reliability of the liquid cooling circuit. This is especially critical for data center liquid cooling systems operating at high hydrostatic pressure.The "low impurity content" of liquid cooling oxygen-free copper is not merely an optimization of material properties, but the physical foundation for the efficient, stable, and long-life operation of high-performance heat dissipation systems. Its near-perfect crystal structure opens a high-speed, unobstructed channel for heat; its extreme chemical purity constructs a robust defense against corrosion. In today's increasingly fierce competition for computing power, it is this "invisible material advantage" that silently supports the conversion of every watt of electricity into effective computing power, allowing the intelligent world to operate continuously and calmly.
