Preparation and Property Modulation of Multi-Grit Diamond/Aluminum Composites Based on Interfacial Strategy

At a Glance

Metadata	Details
Publication Date	2024-07-09
Journal	Metals
Authors	Hao Wu, Sen Yang, Chen Yang, Xiaoxuan He, Changrui Wang
Institutions	Nanjing University of Science and Technology, Nanjing Institute of Railway Technology
Citations	1
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond/Aluminum Composites for High-Performance Heat Sinks

Executive Summary

This research successfully demonstrates the preparation and property modulation of high-performance diamond/aluminum (Diamond/Al) composites using Spark Plasma Sintering (SPS), achieving benchmark thermal and mechanical properties critical for advanced electronic packaging.

Benchmark Performance: Achieved a high Thermal Conductivity (TC) of 660.1 W/mK and a low Coefficient of Thermal Expansion (CTE) of 5.63 x 10^-6/K in a Diamond/Al composite, providing an excellent thermal match for semiconductor materials.
Interfacial Strategy: Performance optimization was achieved by modulating the diamond particle size (optimal at 150 µm) to control the number and coverage area of the microscopic heterogeneous interfaces, thereby minimizing Interfacial Thermal Resistance (ITR).
High Density: The SPS method, combined with optimized parameters, resulted in high relative density (up to 99.5%), which is crucial for avoiding porosity and maximizing heat transfer efficiency.
Mechanical Reliability: The resulting composite exhibited a high flexural bending strength of 304.6 MPa, satisfying the stringent mechanical requirements for reliable heat sink materials in high-heat flow density electronic devices.
6CCVD Relevance: The study underscores the critical role of high-quality diamond reinforcement and precise interfacial engineering, areas where 6CCVD’s expertise in custom MPCVD diamond substrates and metalization services provides direct, high-value solutions.

Technical Specifications

Parameter	Value	Unit	Context
Maximum Thermal Conductivity (TC)	660.1	W/mK	Achieved with 150 µm diamond particles
Minimum Coefficient of Thermal Expansion (CTE)	5.63 x 10^-6/K	/K	Optimal match for semiconductor materials
Maximum Relative Density (RD)	99.5	%	Indicates low porosity and dense organization
Maximum Bending Strength	304.6	MPa	Mechanical reliability for electronic packaging
Optimal Diamond Particle Size	150	µm	Size range tested: 50 µm to 200 µm
Matrix Material	Al-12wt% Si	Alloy	Aluminum metal matrix
Sintering Temperature (SPS)	510	°C	Held constant for 5 minutes
Uniaxial Pressure (SPS)	50	MPa	Applied during sintering process
Initial Al-12Si Particle Size	10	µm	Average particle size of matrix powder

Key Methodologies

The Diamond/Al composites were prepared using the Spark Plasma Sintering (SPS) method, focusing on precise control over material ratios and sintering parameters to optimize interfacial bonding.

Material Selection:
- Matrix: Al-Si alloy powder (12 wt% Si, 10 µm average particle size).
- Reinforcement: MBD4-type synthetic diamond particles (50 µm to 200 µm diameter range).
Proportioning and Mixing:
- Diamond and Al-12Si alloy powders were mixed at a 3:2 volume ratio using a V-type high-efficiency asymmetric mixer.
SPS Preparation:
- Mixed powders were loaded into specific graphite molds.
- The sample chamber was evacuated to below 10 Pa (high vacuum).
SPS Sintering Program:
- Heating Rate: 50 °C/min.
- Maximum Temperature: 510 °C.
- Uniaxial Pressure: Maintained at a constant value of 50 MPa.
- Holding Time: 5 minutes at peak temperature/pressure.
Characterization:
- Density measured via Archimedes Drainage Method (Dahometer DH-300).
- Thermal properties (TC, thermal diffusivity) measured via Laser Flash Method (LINSEIS-LFA).
- CTE measured via LINSEIS thermal expansion coefficient tester (25 °C to 100 °C, 3 °C/min heating rate, Ar atmosphere).
- Microstructure and fracture surfaces analyzed using Field Emission Electron Scanning Microscope (SEM).

6CCVD Solutions & Capabilities

The successful fabrication of high-performance Diamond/Al composites relies fundamentally on the quality of the diamond reinforcement and the engineering of the diamond-metal interface. 6CCVD is uniquely positioned to supply the necessary high-ppurity diamond materials and advanced surface treatments required to replicate or significantly enhance this research.

Applicable Materials

The paper utilized synthetic diamond powder (MBD4-type) as the reinforcement phase. 6CCVD provides the highest quality precursors for such applications, ensuring maximum thermal performance.

6CCVD Material	Description & Application	Relevance to Research
Polycrystalline Diamond (PCD)	High-purity MPCVD PCD plates and wafers, available up to 125mm diameter. These materials serve as superior precursors for high-TC diamond grit used in composite manufacturing.	Provides the highest quality, high-TC diamond material (TC up to 1000 W/mK) necessary to maximize the composite’s overall thermal performance.
Single Crystal Diamond (SCD)	High-purity SCD plates (up to 500 µm thick) with ultra-low defect density (Ra < 1nm polished).	Ideal for applications requiring the absolute highest thermal performance (TC 1800-2000 W/mK). Can be processed into specialized grit sizes or used directly as high-end heat spreaders.
Custom Substrates	Diamond substrates available in thicknesses up to 10mm.	Provides robust, large-format diamond components for direct integration into thermal management systems, bypassing the need for composite sintering in certain designs.

Customization Potential: Interfacial Engineering

The research confirms that Interfacial Thermal Resistance (ITR) is the primary limiting factor for TC (Page 6-7). The formation of Al₄C₃ carbides was observed as a mechanism to improve bonding, but excessive formation reduces TC. 6CCVD addresses this challenge directly through advanced surface modification.

Custom Metalization Services: 6CCVD offers in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu) essential for mitigating ITR. Applying a thin, tailored layer of a carbide-forming metal (like Titanium (Ti) or Tungsten (W)) to the diamond surface prior to sintering significantly enhances wettability and controls the interfacial reaction layer, leading to superior thermal coupling compared to simple particle size modulation alone.
Precision Sizing and Polishing: While the paper focused on 50 µm to 200 µm grit, 6CCVD can supply SCD/PCD materials that can be processed to specific, tightly controlled particle sizes, ensuring optimal volume fraction and interface area for targeted TC/CTE matching. Our polishing capability (Ra < 1nm for SCD) ensures minimal surface defects on precursor materials.

Engineering Support

6CCVD’s in-house team of PhD material scientists specializes in optimizing diamond properties for extreme environments. We offer consultation services to assist engineers and researchers in replicating or extending this work, specifically focusing on:

ITR Mitigation Strategies: Designing optimal metalization schemes (e.g., Ti/Pt/Au stacks) for specific metal matrix composites (Al, Cu, Ag) to maximize phonon transport efficiency.
CTE Matching: Selecting the appropriate diamond material grade and surface treatment to achieve precise CTE matching for specific semiconductor materials (e.g., Si, GaAs, SiC).
Custom Dimensions: Providing custom-sized PCD wafers (up to 125mm) and laser cutting services to meet the exact geometric requirements for heat sink prototypes.

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

View Original Abstract

The development of electronic devices has a tendency to become more complicated in structure, more integrated in function, and smaller in size. The heat flow density of components continues to escalate, which urgently requires the development of heat sink materials with high thermal conductivity and a low coefficient of expansion. Diamond/aluminum composites have become the research hotspot of thermal management materials with excellent thermophysical and mechanical properties, taking into account the advantages of light weight. In this paper, diamond/Al composites are prepared by combining aluminum as matrix and diamond reinforcement through the discharge plasma sintering (SPS) method. The micro-interfacial bonding state of diamond and aluminum is changed by adjusting the particle size of diamond, and the macroscopic morphology performance of the composites is regulated. Through this, the flexible design of diamond/Al performance can be achieved. As a result, when 150 μm diamond powder and A1-12Si powder were used for the composite, the thermal conductivity of the obtained specimens was up to 660.1 W/mK, and the coefficient of thermal expansion was 5.63 × 10−6/K, which was a good match for the semiconductor material. At the same time, the bending strength is 304.6 MPa, which can satisfy the performance requirements of heat-sinking materials in the field of electronic packaging.

Tech Support

Original Source

DOI: https://doi.org/10.3390/met14070801

References

2013 - Diamond/aluminum composites processed by vacuum hot pressing: Microstructure characteristics and thermal properties [Crossref]
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2022 - Effect of basalt fiber on the thermal conductivity and wear resistance of sintered WC-based diamond composites [Crossref]
2021 - Effect of Diamond Particle Size on the Thermal Properties of Diamond/Al Composites for Packaging Substrate
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2023 - Fabrication of diamond/copper composite thin plate based on a single-layer close packed diamond particles network for heat dissipation [Crossref]
2022 - Micro-diamond assisted bidirectional tuning of thermal conductivity in multifunctional graphene nanoplatelets/nanofibrillated cellulose films [Crossref]
2016 - Nucleation and growth mechanisms of interfacial Al 4 C 3 in Al/diamond composites [Crossref]
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