High thermal conductive copper/diamond composites - state of the art
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-10-20 |
| Journal | Journal of Materials Science |
| Authors | S. Q. Jia, Fei Yang |
| Institutions | University of Waikato |
| Citations | 82 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis review analyzes the state-of-the-art in high thermal conductive copper/diamond (Cu/Dia) composites, essential for next-generation thermal management in high-power electronics.
- Core Value Proposition: Cu/Dia composites offer high thermal conductivity (TC) (up to 930 W/mK) combined with a tunable Coefficient of Thermal Expansion (CTE) (4-6 ppm/K), crucial for matching semiconductor chips and preventing thermal stress.
- Critical Bottleneck: The poor chemical affinity between copper and diamond creates high Interfacial Thermal Resistance (ITR), severely limiting the compositeâs effective TC.
- Primary Solution: Introducing carbide-forming elements (Cr, Ti, Zr, B) to create an interfacial layer (a âthermal bridgeâ) that enhances Thermal Boundary Conductance (TBC).
- Optimal Performance: The highest reported TC (930 W/mK) was achieved using Metal Infiltration (MI) with Zr alloying, demonstrating the effectiveness of high-temperature processing in forming homogeneous interfaces.
- Interface Physics: The review emphasizes that TBC is governed by phonon transport mechanisms, which are highly sensitive to interface characteristics like roughness, atomic intermixing, and chemical bonding strength.
- Modeling: Predictive models (Maxwell, Hasselman-Johnson, Differential Effective Medium (DEM)) are used, often requiring the incorporation of calculated TBC values to align with experimental results.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes key performance metrics and processing parameters extracted from the reviewed literature (Tables 1-5).
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Max Thermal Conductivity (TC) | 930 | W/mK | Cu-Zr/Diamond, Metal Infiltration (MI) [19, 52] |
| Max Thermal Boundary Conductance (hc) | 90.9 | MW/m2K | Cu-B/Diamond, Metal Infiltration (MI) [50] |
| Target Coefficient of Thermal Expansion (CTE) | 4-6 | ppm/K | Match semiconductor chip materials |
| Diamond Particle TC (Raw) | Up to 2200 | W/mK | Artificial Diamond reinforcement |
| Typical Diamond Particle Size | 30-400 | ”m | Used across various methods |
| VHP Processing Temperature (Typical) | 900-980 | °C | Below Cu melting point (1080 °C) |
| HTHP Processing Pressure (Max) | 8 | GPa | High-Temperature High-Pressure method [54] |
| Optimal Interface Layer Thickness (Zr) | 320 | nm | Cu-1.2%Zr/Diamond, VHP [32] |
| TBC Range (Highly Dissimilar Materials) | 8-30 | MW/m2K | Theoretical range for materials with Debye temperature ratio of 5-20 [29] |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication of high-performance Cu/Dia composites relies on precise control of temperature, pressure, and alloying elements to optimize the interface layer.
-
Vacuum Hot Pressing (VHP):
- Mechanism: Powder consolidation under simultaneous heat and pressure in a vacuum.
- Recipe Focus: Long holding times (20-30 min) and moderate pressure (up to 80 MPa) to promote element diffusivity and interface bonding below the copper melting point.
- Interface Role: Carbide-forming additives (B, Zr, Cr) are alloyed or coated to form a thin, optimal interface layer (e.g., 320 nm ZrC) that maximizes TBC.
-
Spark Plasma Sintering (SPS):
- Mechanism: Uses high pulsed DC current for rapid heating and small uniaxial pressure for quick densification.
- Recipe Focus: Short sintering times (3-10 min) and temperatures typically maintained below 1000 °C to prevent diamond particle damage.
- Interface Role: High energy at particle contacts cleans surfaces and promotes neck formation quickly, but interface quality is highly dependent on coating/alloying elements (Ti, Cr, Si).
-
Metal Infiltration (MI):
- Mechanism: Molten copper (with additives) infiltrates a diamond preform under low pressure.
- Recipe Focus: High processing temperatures (100-200 °C above copper melting point, e.g., 1150 °C) to enhance metal element diffusion.
- Interface Role: High temperature is favorable for forming a homogeneous interface layer, overcoming the poor chemical affinity, and achieving the highest reported TC values.
-
High-Temperature High-Pressure (HTHP):
- Mechanism: Applying ultrahigh pressure (up to 8 GPa) and high temperature (above 1100 °C).
- Recipe Focus: Extreme conditions ensure high densification and perfect bonding between matrix and particles.
- Results: Capable of fabricating composites with very high diamond volume fractions (up to 90 vol%) and tightly bonded structures.
-
Electrodeposition (ED):
- Mechanism: Electrochemical synthesis at ambient temperature and pressure, where copper is electrodeposited onto precipitated diamond particles.
- Recipe Focus: Precise control of electric current density (e.g., 5-100 mA/cm2) and electrolyte composition.
- Advantages: Simple, cost-effective, and can form chemical bonds without traditional carbide-forming additives, though still in early development stages.
Commercial Applications
Section titled âCommercial ApplicationsâCu/Dia composites are positioned as essential materials for managing heat in modern, high-power density systems where conventional materials fail to meet thermal and mechanical requirements.
- Advanced Electronic Devices:
- Next-generation heat sinks and thermal spreaders for CPUs, GPUs, and high-performance computing modules.
- Addressing the âheat management problemâ bottlenecking performance improvements.
- Semiconductor Packaging:
- Substrates and chip carriers requiring precise CTE matching (4-6 ppm/K) with silicon, GaAs, or GaN chips to minimize thermal fatigue and failure during operation.
- High-Power RF and Microwave Systems:
- Thermal components for high-frequency power amplifiers and radar systems where localized hot spots require immediate and efficient dissipation.
- Automotive and Aerospace:
- Lightweight, high-reliability thermal management solutions for electric vehicle power electronics and defense systems operating under extreme thermal cycling.
- Power Modules:
- Baseplates and cooling elements for IGBTs and other high-power switching devices used in industrial and energy applications.
View Original Abstract
Abstract Copper/diamond composites have drawn lots of attention in the last few decades, due to its potential high thermal conductivity and promising applications in high-power electronic devices. However, the bottlenecks for their practical application are high manufacturing/machining cost and uncontrollable thermal performance affected by the interface characteristics, and the interface thermal conductance mechanisms are still unclear. In this paper, we reviewed the recent research works carried out on this topic, and this primarily includes (1) evaluating the commonly acknowledged principles for acquiring high thermal conductivity of copper/diamond composites that are produced by different processing methods; (2) addressing the factors that influence the thermal conductivity of copper/diamond composites; and (3) elaborating the interface thermal conductance problem to increase the understanding of thermal transferring mechanisms in the boundary area and provide necessary guidance for future designing the composite interface structure. The links between the compositeâs interface thermal conductance and thermal conductivity, which are built quantitatively via the developed models, were also reviewed in the last part.