Interface engineering toward high thermal conductivity in diamond composites

At a Glance

Metadata	Details
Publication Date	2023-01-01
Journal	Materials Lab
Authors	Hailong Zhang
Institutions	Interface (United Kingdom)
Citations	2
Analysis	Full AI Review Included

Interface Engineering in Diamond Composites: 6CCVD Technical Analysis

This document analyzes the research on interface engineering in metal/diamond composites for high-performance thermal management, connecting the findings directly to 6CCVD’s advanced MPCVD diamond material and customization capabilities.

Executive Summary

Core Challenge: Thermal management in high-density electronics requires materials with high Thermal Conductivity (TC) and tailorable Coefficient of Thermal Expansion (CTE). Metal/Diamond (M/D) composites are ideal, but performance is limited by the interfacial mismatch.
Key Achievement: Interface engineering successfully yielded M/D composites with TC exceeding 900 W m^-1 K^-1 at moderate diamond content, significantly improving upon unmodified materials.
Dominant Mechanism: The research suggests that the acoustic bridging effect (using interlayers like carbides to match vibrational density of states) is the key mechanism surpassing the traditional bonding effect in enhancing Interfacial Thermal Conductance (ITC).
Optimal Structure: Maximum TC is achieved by manipulating discontinuous interfacial carbide layers, specifically targeting high coverage but small thickness (ideally < 50 nm).
Modification Routes: Successful strategies include diamond surface metallization (TiC, WC, B₄C), metal matrix alloying, oxygen termination, and surface roughening.
6CCVD Value Proposition: 6CCVD provides the high-purity Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) substrates and custom metalization services necessary to replicate and advance these critical interface engineering studies.

Technical Specifications

The following hard data points were extracted from the analysis of high-performance diamond composites and interface properties:

Parameter	Value	Unit	Context
Intrinsic Diamond Thermal Conductivity (TC)	2200	W m^-1 K^-1	Ideal reinforcement property
Intrinsic Diamond Coefficient of Thermal Expansion (CTE)	1 x 10^-6	K^-1	Low CTE, crucial for thermal stress mitigation
Achieved TC (Al/Diamond, Discontinuous Carbide)	1021	W m^-1 K^-1	High performance composite
Achieved TC (Cu-B/Diamond, Discontinuous Carbide)	913	W m^-1 K^-1	High performance composite
Target Interfacial Carbide Thickness	< 50	nm	Ultra-thin layer required for optimal thermal conductivity
Interfacial Thermal Conductance (ITC) Increase (Al/Diamond, O-termination)	23 to 165	MW m^-2 K^-1	Significant enhancement via oxygen termination
Diamond Content (HTHP Cu/Dia)	~90	vol%	Required for high TC using traditional HTHP method
Metal CTE Range	15-25 x 10^-6	K^-1	Large mismatch with diamond (1 x 10^-6 K^-1)

Key Methodologies

The research focuses on manipulating the interface between the metal matrix and the diamond reinforcement to optimize phonon transmission. Key experimental and theoretical methodologies include:

Diamond Surface Metallization: Applying thin films of carbide-forming elements (e.g., Ti, W, Mo, B, Zr) onto the diamond surface to create a continuous interfacial carbide layer (e.g., TiC, WC, B₄C).
Metal Matrix Alloying: Introducing alloying elements into the metal matrix (e.g., Boron into Copper) to facilitate the in situ formation of a discontinuous interfacial carbide layer during composite processing.
Interface Structure Regulation: Precise control over the carbide layer morphology to achieve high coverage but minimal thickness, thereby maximizing fast heat transfer channels while minimizing thermal resistance.
Surface Chemical Modification: Introducing specific chemical terminations, such as oxygen terminations (C-O bonds), to the diamond surface to increase interfacial bond strength and enhance ITC.
Surface Physical Modification: Roughening the diamond surface (e.g., using molten salts) to increase the contact area and provide more heat transfer channels between the metal and diamond.
Acoustic Bridging Analysis: Utilizing vibrational density of states (VDOS) analysis to confirm that interlayers (carbides) effectively bridge the vibrational mismatch between the metal and diamond, enhancing phonon transmission.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced diamond materials and surface engineering required to replicate and extend this research into high-performance thermal management applications.

Applicable Materials

To achieve the high intrinsic thermal conductivity required for maximizing composite performance, researchers should utilize:

Optical Grade SCD (Single Crystal Diamond): Provides the highest purity and intrinsic thermal conductivity (up to 2200 W m^-1 K^-1) for fundamental studies of interfacial thermal conductance (ITC) on flat substrates.
High Purity PCD (Polycrystalline Diamond): Ideal for scaling up composite research, offering large area plates (up to 125mm) with excellent thermal properties for use as substrates or source material for diamond particles.

Customization Potential

The paper highlights the critical need for precise interface control, particularly ultra-thin carbide layers and specific metal terminations. 6CCVD’s internal capabilities directly address these requirements:

Research Requirement	6CCVD Customization Service	Benefit to Researcher
Precise Interlayer Deposition	Custom Metalization: Au, Pt, Pd, Ti, W, Cu (Carbide-forming elements)	Enables precise control over the thickness of the deposited metal layer, critical for achieving the optimal < 50 nm interfacial carbide thickness.
Large-Area Composite Testing	Custom Dimensions: Plates/wafers up to 125mm (PCD)	Supports the fabrication and testing of large-scale thermal management devices and electronic packaging components.
Substrate Thickness Control	SCD/PCD Thickness: 0.1µm to 500µm (Wafers), Substrates up to 10mm	Provides flexibility for both thin-film ITC studies and robust, thick substrates for high-power applications.
Baseline Surface Quality	Precision Polishing: Ra < 1nm (SCD), Ra < 5nm (Inch-size PCD)	Ensures a highly consistent, ultra-smooth starting surface for controlled chemical modification (e.g., oxygen termination) or controlled roughening experiments.

Engineering Support

6CCVD’s in-house PhD team specializes in MPCVD growth and material science. We can assist researchers and engineers with:

Material Selection: Guiding the choice between SCD and PCD based on purity, size, and cost constraints for specific thermal management projects.
Interface Recipe Development: Consulting on optimal metalization parameters (material, thickness, deposition method) required to replicate or extend the discontinuous interfacial carbide manipulation techniques discussed in the paper.
Advanced Characterization: Providing support for material specifications necessary for subsequent processing steps like electroplating or high-temperature alloying.

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

View Original Abstract

Diamond particle reinforced metal matrix (metal/diamond) composites with high thermal conductivity and tailorable coefficient of thermal expansion are an ideal thermal management material for electronic packaging applications. Interface engineering is the key to designing metal/diamond composites due to large difference between metal and diamond in both chemical and physical nature. In this paper, we briefly summarize recent progress in the interface engineering of metal/diamond composites and give some perspectives on future development in this field.

Tech Support

Original Source

DOI: https://doi.org/10.54227/mlab.20230004