Since the 1980s, the integration density of electronic circuits has been increasing at an annual rate of 1.5× or faster. Higher integration leads to greater current densities and heat generation during operation. If not dissipated efficiently, this heat can cause thermal failure and reduce the lifespan of electronic components.
To meet escalating thermal management demands, advanced electronic packaging materials with superior thermal conductivity are being extensively researched and optimized.
Diamond/copper composite material
01 Diamond and Copper
Traditional packaging materials include ceramics, plastics, metals, and their alloys. Ceramics like BeO and AlN exhibit CTEs matching semiconductors, good chemical stability, and moderate thermal conductivity. However, their complex processing, high cost (especially toxic BeO), and brittleness limit applications. Plastic packaging offers low cost, light weight, and insulation but suffers from poor thermal conductivity and high-temperature instability. Pure metals (Cu, Ag, Al) have high thermal conductivity but excessive CTE, while alloys (Cu-W, Cu-Mo) compromise thermal performance. Thus, novel packaging materials balancing high thermal conductivity and optimal CTE are urgently needed.
| Reinforcement | Thermal Conductivity (W/(m·K)) | CTE (×10⁻⁶/℃) | Density (g/cm³) |
| Diamond | 700–2000 | 0.9–1.7 | 3.52 |
| BeO particles | 300 | 4.1 | 3.01 |
| AlN particles | 150–250 | 2.69 | 3.26 |
| SiC particles | 80–200 | 4.0 | 3.21 |
| B₄C particles | 29–67 | 4.4 | 2.52 |
| Boron fiber | 40 | ~5.0 | 2.6 |
| TiC particles | 40 | 7.4 | 4.92 |
| Al₂O₃ particles | 20–40 | 4.4 | 3.98 |
| SiC whiskers | 32 | 3.4 | – |
| Si₃N₄ particles | 28 | 1.44 | 3.18 |
| TiB₂ particles | 25 | 4.6 | 4.5 |
| SiO₂ particles | 1.4 | <1.0 | 2.65 |
Diamond, the hardest known natural material (Mohs 10), also possesses exceptional thermal conductivity (200–2200 W/(m·K)).
Diamond micro-powder
Copper, with high thermal/electrical conductivity (401 W/(m·K)), ductility, and cost efficiency, is widely used in ICs.
Combining these properties, diamond/copper (Dia/Cu) composites—with Cu as the matrix and diamond as reinforcement—are emerging as next-generation thermal management materials.
02 Key Fabrication Methods
The common methods for preparing diamond/copper include: powder metallurgy, high-temperature and high-pressure method, melt immersion method, discharge plasma sintering method, cold spraying method, etc.
Comparison of different preparation methods, processes and properties of single-particle size diamond/copper composites
| Parameter | Powder Metallurgy | Vacuum Hot-Pressing | Spark Plasma Sintering (SPS) | High-Pressure High-Temperature (HPHT) | Cold Spray Deposition | Melt Infiltration |
| Diamond Type | MBD8 | HFD-D | MBD8 | MBD4 | PDA | MBD8/HHD |
| Matrix | 99.8% Cu powder | 99.9% electrolytic Cu powder | 99.9% Cu powder | Alloy/pure Cu powder | Pure Cu powder | Pure Cu bulk/rod |
| Interface Modification | – | – | – | B, Ti, Si, Cr, Zr, W, Mo | – | – |
| Particle Size (μm) | 100 | 106–125 | 100–400 | 20–200 | 35–200 | 50–400 |
| Volume Fraction (%) | 20–60 | 40–60 | 35–60 | 60–90 | 20–40 | 60–65 |
| Temperature (°C) | 900 | 800–1050 | 880–950 | 1100–1300 | 350 | 1100–1300 |
| Pressure (MPa) | 110 | 70 | 40–50 | 8000 | 3 | 1–4 |
| Time (min) | 60 | 60–180 | 20 | 6–10 | – | 5–30 |
| Relative Density (%) | 98.5 | 99.2–99.7 | – | – | – | 99.4–99.7 |
| Performance | ||||||
| Optimal Thermal Conductivity (W/(m·K)) | 305 | 536 | 687 | 907 | – | 943 |
Common Dia/Cu composite techniques include:
(1) Powder Metallurgy
Mixed diamond/Cu powders are compacted and sintered. While cost-effective and simple, this method yields limited density, inhomogeneous microstructures, and restricted sample dimensions.
Sintering unit
(1) High-Pressure High-Temperature (HPHT)
Using multi-anvil presses, molten Cu infiltrates diamond lattices under extreme conditions, producing dense composites. However, HPHT requires expensive molds and is unsuitable for large-scale production.
Cubic press
(1) Melt Infiltration
Molten Cu permeates diamond preforms via pressure-assisted or capillary-driven infiltration. Resulting composites achieve >446 W/(m·K) thermal conductivity.
(2) Spark Plasma Sintering (SPS)
Pulsed current rapidly sinters mixed powders under pressure. Although efficient, SPS performance degrades at diamond fractions >65 vol%.
Schematic diagram of the discharge plasma sintering system
(5) Cold Spray Deposition
Powders are accelerated and deposited onto substrates. This nascent method faces challenges in surface finish control and thermal performance validation.
03 Interface Modification
For the preparation of composite materials, the mutual wetting between components is a necessary prerequisite for the composite process and an important factor affecting the interface structure and interface bonding state. The non-wetting condition at the interface between diamond and Cu leads to a very high interface thermal resistance. Therefore, it is very crucial to conduct modification research on the interface between the two through various technical means. At present, there are mainly two methods to improve the interface problem between diamond and Cu matrix: (1) Surface modification treatment of diamond; (2) Alloying treatment of the copper matrix.
Modification schematic diagram: (a) Direct plating on the surface of diamond; (b) Matrix alloying
(1) Surface modification of diamond
Plating active elements such as Mo, Ti, W and Cr on the surface layer of the reinforcing phase can improve the interfacial characteristics of diamond, thereby enhancing its thermal conductivity. Sintering can enable the above elements to react with the carbon on the surface of the diamond powder to form a carbide transition layer. This optimizes the wetting state between the diamond and the metal base, and the coating can prevent the structure of the diamond from changing at high temperatures.
(2) Alloying of the copper matrix
Before the composite processing of materials, pre-alloying treatment is carried out on metallic copper, which can produce composite materials with generally high thermal conductivity. Doping active elements in the copper matrix can not only effectively reduce the wetting Angle between diamond and copper, but also generate a carbide layer that is solid soluble in the copper matrix at the diamond /Cu interface after the reaction. In this way, most of the gaps existing at the material interface are modified and filled, thereby improving the thermal conductivity.
04 Conclusion
Conventional packaging materials fall short in managing heat from advanced chips. Dia/Cu composites, with tunable CTE and ultrahigh thermal conductivity, represent a transformative solution for next-generation electronics.
As a high-tech enterprise integrating industry and trade, XKH focuses on the research and development and production of diamond/copper composites and high-performance metal matrix composites such as SiC/Al and Gr/Cu, providing innovative thermal management solutions with thermal conductivity of over 900W/(m·K) for the fields of electronic packaging, power modules and aerospace.
XKH’s Diamond copper clad laminate composite material:
Post time: May-12-2025