High Thermal Conductivity Diamond–Copper Composites Prepared via Hot Pressing with Tungsten–Coated Interfacial Layer Optimization

At a Glance

Metadata	Details
Publication Date	2025-08-19
Journal	Materials
Authors	Qiang Wang, Zhijie Ye, Lei Liu, Jie Bai, Yuning Zhao
Institutions	Harbin Institute of Technology, Chongqing Jiaotong University
Citations	1
Analysis	Full AI Review Included

Technical Documentation & Analysis: High Thermal Conductivity Diamond-Copper Composites

Executive Summary

This research demonstrates a significant advancement in thermal management materials by optimizing diamond-copper (D-Cu) composites via precise interfacial engineering, providing a high-performance solution for high-power electronics.

Benchmark Performance: Achieved a peak thermal conductivity (TC) of 640 W/(m·K) in a D-Cu composite containing 50 vol% diamond, establishing the highest reported value for hot-press sintered composites at or below this diamond volume fraction.
Interface Optimization: Thermal performance was critically enhanced by utilizing a 200 nm Tungsten (W) transition layer deposited via magnetron sputtering, followed by high-temperature annealing.
Optimal Structure Identified: The highest TC correlated with a 2-hour, 1100 °C annealing process, resulting in a stable, low-resistance interfacial structure modeled as Diamond/W₂C/WC/W₂C/Cu.
Mechanism Validation: Acoustic Mismatch Model (AMM) and Diffusion Mismatch Model (DMM) calculations confirmed that this optimized interface structure minimizes amorphous carbon formation and achieves an interfacial thermal conductance (ITC) of 36-56 MW/(m²K).
Application Potential: The resulting composite material offers superior thermal dissipation capabilities, making it ideal for high-power electronic device cooling, aerospace applications, and advanced chip manufacturing where traditional materials are inadequate.

Technical Specifications

The following hard data points were extracted from the experimental results and theoretical modeling:

Parameter	Value	Unit	Context
Peak Composite Thermal Conductivity (TC)	640	W/(m·K)	50 vol% Diamond, 2 h Annealing
Diamond Particle Intrinsic TC (Calculated)	1717	W/(m·K)	Based on 147 ppm Nitrogen content
Diamond Volume Fraction	50	%	Optimized composition
Diamond Particle Size (Average)	400	µm	Substrate material
Tungsten Coating Thickness	200	nm	Deposited via magnetron sputtering
Annealing Temperature	1100	°C	Vacuum environment
Optimal Annealing Time	2	h	Yields peak TC and optimal interface
Optimal Interfacial Thermal Conductance (ITC)	36 - 56	MW/(m²K)	Calculated using H-J and DEM models
Lowest ITC (a-C/Diamond)	2.59	MW/(m²K)	Demonstrates necessity of carbide layer
Optimal Interface Structure	Diamond/W₂C/WC/W₂C/Cu	N/A	Validated by AMM/DMM modeling
Final Composite Dimensions	12.7 (Diameter) x 1.5 (Thickness)	mm	Laser cut disc

Key Methodologies

The high-performance diamond-copper composites were fabricated using a multi-step process focused on precise surface modification and high-density sintering:

Diamond Cleaning: Diamond particles (400 µm) were thoroughly cleaned using sequential immersion in strong acids (nitric acid) and bases (sodium hydroxide), followed by ultrasonic cleaning in organic solvents (acetone, ethanol) to remove surface impurities.
Tungsten (W) Coating: A 200 nm W layer was deposited onto the rotating diamond particles using pulsed magnetron sputtering in an Argon atmosphere to ensure uniform coverage.
Carbide Conversion: The W-coated particles were annealed at 1100 °C under high vacuum (5 x 10^-4 Pa) for varying durations (0 to 6 h). The optimal 2 h duration facilitated the complete conversion of W into stable tungsten carbides (WC and W₂C).
Copper Coating: The metallized and annealed diamond particles were activated, sensitized, and then coated with a copper layer via chemical deposition (immersion plating) in a rotary evaporator.
Hot Press Sintering (HPS): The diamond-copper powder mixture (50 vol% diamond) was consolidated using HPS to form dense composite materials (30 mm diameter, 1.5 mm thickness).
Microstructural Analysis: XRD, SEM, Raman spectroscopy, and high-resolution TEM/FIB were used to characterize phase composition (W, W₂C, WC) and confirm the dense, low-porosity interfacial bonding.

6CCVD Solutions & Capabilities

This research highlights the critical role of high-quality diamond material and precision interface engineering—areas where 6CCVD provides industry-leading expertise and custom manufacturing capabilities.

Applicable Materials for Replication and Extension

The success of this study relies on diamond particles with high intrinsic thermal conductivity (1717 W/(m·K)). 6CCVD offers materials that meet or exceed these requirements for both particulate and substrate applications:

Optical Grade Single Crystal Diamond (SCD): For applications requiring the highest intrinsic thermal conductivity (up to 2000 W/(m·K)) and ultra-low nitrogen content, ideal for fundamental research or high-end thermal spreaders.
High-Thermal Grade Polycrystalline Diamond (PCD): Available in large plates/wafers up to 125mm, providing excellent thermal performance (often >1500 W/(m·K)) suitable for large-scale composite fabrication and industrial heat sink applications.
Custom Diamond Substrates: 6CCVD can supply SCD or PCD substrates up to 10mm thick, which can serve as robust, pre-sintered bases for D-Cu composite layering or integration into complex thermal stacks.

Customization Potential & Manufacturing Synergy

The precise control over coating thickness, material composition, and final dimensions demonstrated in this paper aligns perfectly with 6CCVD’s core capabilities:

Research Requirement	6CCVD Capability	Value Proposition
Tungsten (W) Interlayer: 200 nm thickness, W/W₂C/WC composition.	Internal Metalization Services: We offer high-precision deposition of W, Ti, Cu, Pt, Pd, and Au layers. We can replicate or optimize the 200 nm W coating recipe for specific carbide formation targets.	Guaranteed control over transition layer thickness and composition, crucial for minimizing Thermal Interface Resistance (TIR).
Custom Dimensions: 12.7 mm diameter discs, 1.5 mm thickness.	Precision Shaping & Cutting: Custom laser cutting and shaping services are standard. We produce plates/wafers up to 125mm (PCD) or custom shapes from SCD, ensuring uniform properties post-sintering.	Provides ready-to-integrate components, reducing post-processing costs and ensuring dimensional accuracy for device integration.
Interface Modeling: Need for precise material parameters (density, specific heat, velocity) for AMM/DMM.	Comprehensive Material Characterization: We provide detailed specifications for our SCD and PCD materials, including nitrogen content (FTIR), surface roughness (Ra < 1nm SCD), and crystallographic orientation.	Enables accurate theoretical modeling and prediction of composite performance before fabrication, accelerating R&D cycles.

Engineering Support

The optimization of the Diamond/W₂C/WC/W₂C/Cu interface structure is a complex materials science challenge. 6CCVD’s in-house PhD engineering team specializes in CVD diamond interface physics and can assist clients with similar High-Power Electronic Cooling projects.

We offer consultation on:

Transition Layer Selection: Guidance on selecting optimal metalization layers (W, Ti, Cr, Mo, etc.) based on desired carbide formation kinetics and matrix material compatibility (Cu, Al, Ag).
Process Recipe Development: Assistance in defining optimal annealing temperatures, vacuum levels, and sintering pressures to achieve dense composites with minimal amorphous carbon formation.
Thermal Modeling Integration: Utilizing advanced models (like AMM/DMM) to predict and validate interfacial thermal conductance for new composite designs.

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

View Original Abstract

Diamond-copper composites, due to their exceptional thermal conductivity, hold significant potential in the field of electronic device thermal management. Hot-press sintering is a promising fabrication technique with industrial application prospects; however, the thermal conductivity of composites prepared by this method has yet to reach optimal levels. In this study, tungsten was deposited on the surface of diamond particles by magnetron sputtering as an interfacial transition layer, and hot-press sintering was employed to fabricate the composites. The findings reveal that with prolonged annealing time, tungsten gradually transformed into W2C and WC, significantly enhancing interfacial bonding strength. When the diamond volume content was 50% and the interfacial coating consisted of 2 wt.% W, 92 wt.% WC, and 6 wt.% W2C, the composite exhibited a thermal conductivity of 640 W/(m·K), the highest value reported among hot-press sintered composites with diamond content below 50%. Additionally, the AMM (Acoustic Mismatch Model) and DMM (Diffusion Mismatch Model) models were utilized to calculate the interfacial thermal conductance between different phases, identifying the optimal interfacial structure as diamond/W2C/WC/W2C/Cu. This composite material shows potential for application in high-power electronic device cooling, thermal management systems, and thermoelectric conversion, providing a more efficient thermal dissipation solution for related devices.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma18163882

References

2018 - Theoretical modelling for interface design and thermal conductivity prediction in diamond/Cu composites [Crossref]
2021 - Reinforcement size effect on thermal conductivity in Cu-B/diamond composite [Crossref]
2020 - High-Temperature Thermal Conductivity and Thermal Cycling Behavior of Cu-B/Diamond Composites [Crossref]
2012 - Preparation of Si-diamond-SiC composites by in-situ reactive sintering and their thermal properties [Crossref]
2018 - Combining Cr pre-coating and Cr alloying to improve the thermal conductivity of diamond particles reinforced Cu matrix composites [Crossref]
2018 - Enhanced thermal conductivity in Cu/diamond composites by tailoring the thickness of interfacial TiC layer [Crossref]