Using diamond/copper composite material increases the heat transfer coefficient by three times.

Recently, Youyan Group The team of Sun Mingmei and Guo Hong from the State Key Laboratory of Nonferrous Metals and Processing at the Limited Company has innovatively developed three structurally integrated, open-type microchannel heat sinks (DC60, DC75, and MoCu50), using low-linear-expansion materials such as DC and molybdenum-copper as the base. They conducted flow boiling experiments with deionized water as the working fluid and combined these tests with visualization techniques to investigate the heat transfer characteristics. The results reveal that, during the boiling process, the high thermal conductivity network plays a significant role in enhancing heat dissipation. Diamond /The Cu microchannel surface has more nucleation sites compared to the MoCu50 microchannel, making nucleate boiling the dominant mechanism in the phase-change heat transfer process and significantly enhancing thermal performance. DC75 maintains a clear advantage even at the highest heat flux density of q" = 4012.14 kW/m², achieving a heat transfer coefficient that is three times higher than that of MoCu50—peaking at 127.48 kW/m²·K—while also demonstrating no dryout phenomenon. Additionally, DC75 exhibits the lowest bottom temperature and minimal deformation, showcasing exceptional thermal stability. During the transition from slug flow to stratified flow, a synergistic effect between these two flow regimes emerges, allowing them to coexist without causing significant pressure fluctuations; the maximum pressure drop remains below 3.5 kPa. The research findings, titled "Subcooled Flow Boiling in Diamond/Cu Microchannel Heat Sinks for Near-Junction Chip Cooling," have been published in the journal *Case Studies in Thermal Engineering*.

It is reported that the accumulation of heat poses a significant threat to the reliability and longevity of equipment, making thermal management an increasingly critical issue for high-power chips. Chip-level microchannel cooling has garnered widespread research attention, as its integrated structural and functional design can effectively reduce thermal resistance in chip packaging and enhance heat dissipation. However, this approach also places higher demands on the structural integrity and operational stability of the system. Most microchannel heat sinks are currently fabricated from aluminum or copper—materials that exhibit markedly different coefficients of thermal expansion compared to semiconductor chips. As a result, thermal interface layers (thermal substrates) must be incorporated during chip packaging to facilitate smooth thermal transitions, a requirement that could inadvertently lead to an increase in the overall thermal resistance within the chip assembly. In contrast, metal-based solutions designed for thermal management are gaining traction as a more promising alternative. Composite materials These materials are better suited to complement third-generation semiconductor materials, offering superior thermal management performance. Currently, four generations of thermal management materials have been developed—evolving from traditional alloys to metal composites, then to aluminum-based composites, and finally reaching the fourth generation, represented by diamond-metal composites. Diamond boasts exceptional thermal conductivity, ranging from 2200 W/mK to 2600 W/mK, along with an impressively low coefficient of thermal expansion. By combining diamond with high-thermal-conductivity metal copper, researchers have created diamond/copper (DC) composites specifically designed for thermal management applications. These composites not only exhibit a reduced coefficient of thermal expansion but also deliver outstanding thermal conductivity. Such thermal management materials, characterized by their low linear thermal expansion and high thermal conductivity, enable "near-junction cooling" of chips. However, the latest-generation diamond/copper (DC) composites have so far seen limited application research in microchannel-based phase-change cooling systems.