Enhancement Effect of a Diamond Network on the Flow Boiling Heat Transfer Characteristics of a Diamond/Cu Heat Sink

At a Glance

Metadata	Details
Publication Date	2023-10-24
Journal	Energies
Authors	Nan Wu, M. Sun, Guo Hong, Zhongnan Xie, Shijie Du
Institutions	General Research Institute for Nonferrous Metals (China), State Key Laboratory of Nonferrous Metals and Processes
Citations	11
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond Network Enhanced Flow Boiling Heat Sinks

Executive Summary

This research validates the critical role of diamond-based materials in achieving ultra-efficient thermal management for high-power electronics, specifically utilizing flow boiling in micro heat sinks.

Superior Thermal Performance: The diamond/Cu composite heat sink demonstrated a significant 38-51% improvement in the heat transfer coefficient ($h$) compared to a pure copper heat sink under identical flow boiling conditions.
Enhanced Stability and Uniformity: The diamond/Cu material reduced the wall superheat ($\Delta T_{sat}$) by 10.2-14.5 °C and drastically improved thermal uniformity, showing a 29% lower temperature difference ($\Delta T$) and a 39% lower temperature fluctuation ($\sigma$) at high heat fluxes (up to 1600 kW/m²).
Mechanism Verified: The enhanced performance is directly attributed to the creation of a three-dimensional diamond heat conduction network, which increases internal heat flux and provides a higher density of active nucleation sites for stable boiling.
Interface Engineering: The study highlights the necessity of interfacial thermal conductivity control. The in-situ growth of a Cr₃C₂ layer (610 nm thick) between the diamond and copper matrix was crucial for low thermal resistance and excellent bonding strength.
6CCVD Value Proposition: This work confirms that diamond materials are essential for next-generation microchannel heat sinks (MCHSs). 6CCVD provides the necessary high-quality Polycrystalline Diamond (PCD) and Single Crystal Diamond (SCD) substrates, along with custom metalization and processing capabilities, required to replicate and scale this advanced thermal solution.

Technical Specifications

Data extracted from the experimental results and material characterization of the diamond/Cu composite heat sink.

Parameter	Value	Unit	Context
Diamond/Cu Thermal Conductivity ($\lambda$)	780	W/(m·K)	Composite material property
Diamond/Cu CLTE	4.0 x 10^-6	/K	Coefficient of Linear Thermal Expansion (matches semiconductors)
Heat Transfer Coefficient ($h$) Enhancement	38 - 51	%	Compared to pure Cu heat sink
Wall Superheat ($\Delta T_{sat}$) Reduction	10.2 - 14.5	°C	Compared to pure Cu heat sink
Heat Sink Dimensions	10 x 20 x 2	mm	Processed size of the diamond/Cu heat sink
Specific Mass Flux ($G$)	507	kg/m²s	Fixed experimental flow condition
High Heat Flux Tested ($q”$)	1610.75	kW/m²	High-performance operating point
Temperature Difference ($\Delta T$) Reduction	29	%	At 1600 kW/m², compared to Cu
Temperature Fluctuation ($\sigma$) Reduction	39	%	Compared to Cu heat sink
Cr₃C₂ Interface Layer Thickness	610	nm	Continuous, uniform layer for low thermal resistance
Cu-Cr₃C₂ Interfacial Thermal Conductivity ($h_{IF}$)	5.138 x 10⁸	W/m²K	Calculated using Diffusion Mismatch Model (DMM)

Key Methodologies

The fabrication and testing relied on precise material engineering and advanced thermal modeling.

Bimodal Diamond Particle Preparation: Main diamond particles (400 µm) were uniformly mixed with secondary diamond particles (30-40 µm) to ensure gap filling and the formation of a complex, three-dimensional heat conduction network.
Network Formation: The diamond mixture was combined with a binder and vacuum dried at 450 °C for 60 minutes.
Liquid Phase Infiltration (LPI): Cu-Cr alloy (1.0 wt% Cr) was heated to 1250 °C and poured into a mold containing the diamond network. A vertical pressure of 60 MPa was applied to force infiltration.
Interface Control: The Cr element in the Cu-Cr alloy reacted with the diamond surface during high-temperature preparation, forming a low-mismatch Cr₃C₂ interface layer to enhance bonding and reduce interfacial thermal resistance.
Flow Boiling Experimentation: Experiments were conducted in a closed-loop system using deionized water, monitored by K-type and T-type thermocouples (±0.20 °C and ±0.30 °C uncertainty, respectively) and controlled by a DC power supply.
Thermal Modeling: A transient thermal model was coupled with Computational Fluid Dynamics (CFD) software (ANSYS Fluent 19.0). The Diffusion Mismatch Model (DMM) was used to accurately calculate the interfacial thermal conductivity coefficients ($h_{IF}$) between the diamond, Cr₃C₂, and Cu layers, allowing for highly accurate simulation of the flow boiling performance.

6CCVD Solutions & Capabilities

The research demonstrates that high-performance thermal management solutions require diamond materials with precise geometry and controlled interfaces—core competencies of 6CCVD.

Applicable Materials

To replicate or extend this research, high-quality diamond precursors are essential. 6CCVD recommends the following materials:

Polycrystalline Diamond (PCD) Substrates: Ideal for large-scale thermal management applications. 6CCVD offers PCD plates/wafers up to 125 mm in diameter and thicknesses up to 500 µm. These substrates can serve as the high-conductivity base material for microchannel etching or as the high-purity diamond source material for composite fabrication (as used in this study).
Optical Grade Single Crystal Diamond (SCD): For applications requiring the absolute highest thermal conductivity (up to 2000 W/mK) or ultra-low surface roughness (Ra < 1 nm). SCD can be used for smaller, extremely high-flux MCHSs or as windows for in-situ optical monitoring of boiling phenomena.

Customization Potential

The success of the diamond/Cu heat sink relied heavily on precise geometry and interface engineering. 6CCVD provides the necessary customization services to meet these demanding specifications:

Requirement from Paper	6CCVD Capability	Technical Advantage
Custom Dimensions (10 x 20 x 2 mm)	Custom plates/wafers up to 125 mm (PCD) and substrates up to 10 mm thick.	Enables scaling from R&D prototypes to production-ready, inch-size wafers for high-volume manufacturing.
Interface Bonding (Cr₃C₂ layer)	In-house Metalization Services: We offer deposition of Ti, W, Cu, Pt, Pd, and Au.	Allows researchers to test various adhesion layers (e.g., Ti/Pt/Au stacks) to optimize interfacial thermal conductivity ($h_{IF}$) for specific composite matrices (Cu, Al, Ag).
Surface Quality (Nucleation Sites)	Precision Polishing: Ra < 1 nm (SCD) and Ra < 5 nm (Inch-size PCD).	We can provide surfaces with controlled roughness, crucial for tailoring the density and stability of nucleation sites in flow boiling applications.
Material Thickness (2.0 mm heat sink)	SCD/PCD thickness range from 0.1 µm to 500 µm (wafers) and up to 10 mm (substrates).	Provides flexibility for designing thin-film heat spreaders or thick, robust microchannel structures.

Engineering Support

6CCVD’s in-house PhD team specializes in advanced diamond material science and thermal management applications. We can assist researchers and engineers with:

Material Selection: Optimizing PCD grain size and purity for maximum thermal network efficiency in composite fabrication.
Interface Engineering: Consulting on appropriate metalization schemes (e.g., Ti/W/Cu) to achieve low thermal boundary resistance, critical for high-flux Flow Boiling Heat Transfer projects.
Design for Manufacturing: Providing diamond materials pre-processed to specific dimensions and tolerances, ready for integration into microchannel heat sink fabrication processes.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The use of a micro heat sink is an effective means of solving the problem of high-power chip heat dissipation. Diamond/Cu composites exhibit high thermal conductivity and a linear thermal expansion coefficient that is compatible with semiconductor materials, rendering them ideal micro heat sink materials. The aim of this study was to fabricate diamond/Cu and Cu separately as heat sinks and subject them to flow boiling heat transfer experiments. The results indicate that the diamond/Cu heat sink displayed a decrease in wall superheat of 10.2-14.5 °C and an improvement in heat transfer coefficient of 38-51% compared with the Cu heat sink under identical heat fluxes. The heat sink also exhibits enhanced thermal uniformity. Secondary diamond particles are incorporated into the gaps of the main diamonds, thereby constructing a three-dimensional heat conduction network within the composite material. The diamond network enhances the internal heat flux of the material while also creating more nucleation sites on the surface. These increase the boiling intensity of the diamond/Cu heat sink, leading to better heat transfer performance. By combining the transient thermal model with computational fluid dynamics, a heat transfer model based on the diamond/Cu heat sink is proposed. The efficient heat dissipation capability of diamond/Cu heat sinks can lower the working temperature of microelectronic devices, thereby improving device performance and reliability during operation.

Tech Support

Original Source

DOI: https://doi.org/10.3390/en16217228

References

2018 - Experimental observation of high thermal conductivity in boron arsenide [Crossref]
2017 - Heat transfer augmentation in a microchannel heat sink with sinusoidal cavities and rectangular ribs [Crossref]
2018 - Low-cost nanostructures from nanoparticle-assisted large-scale lithography significantly enhance thermal energy transport across solid interfaces [Crossref]
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2022 - Hybrid nanofluid spray cooling performance and its residue surface effects: Toward thermal management of high heat flux devices [Crossref]
2022 - Structure optimization of a heat pipe-cooling battery thermal management system based on fuzzy grey relational analysis [Crossref]
2021 - Experimental study of flow boiling performance of open-ring pin fin microchannels [Crossref]
2008 - Thermal conductivity of Al-SiC composites with monomodal and bimodal particle size distribution [Crossref]