Effect of Boron Addition on the Thermal Conductivity of Cu/Diamond Composites Fabricated by SPS
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-01-01 |
| Journal | Journal of the Japan Society of Powder and Powder Metallurgy |
| Authors | Kiyoshi Mizuuchi, Kanryu INOUE, Yasuyuki Agari, Masami Sugioka, Motohiro Tanaka |
| Institutions | University of Washington, The University of Osaka |
| Citations | 6 |
| Analysis | Full AI Review Included |
6CCVD Technical Analysis & Market Opportunity: Enhanced Thermal Performance of Cu/Diamond Composites via Boron Interfacial Doping
Section titled â6CCVD Technical Analysis & Market Opportunity: Enhanced Thermal Performance of Cu/Diamond Composites via Boron Interfacial DopingâThis technical document analyzes the research detailing the fabrication and optimization of Cu/Diamond composite materials using Spark Plasma Sintering (SPS) and Boron (B) additives. It connects the demonstrated need for superior thermal interfaces to 6CCVDâs advanced CVD diamond capabilities, driving material recommendations and service sales.
Executive Summary
Section titled âExecutive SummaryâThe analyzed research successfully demonstrated a major advancement in enhancing the thermal conductivity ($\lambda$) of Copper/Diamond composites by utilizing Boron (B) as an interfacial bonding agent during Spark Plasma Sintering (SPS).
- Performance Leap: Thermal conductivity increased from 152 W/mK (Cu-Diamond, 50 vol% D) to a maximum of 689 W/mK by introducing 7.2 vol% B into the Cu matrix.
- Mechanism Confirmation: The massive thermal improvement is attributed to the dramatic increase in interfacial thermal boundary conductance ($h_{c}$), suggesting that B promotes strong chemical bonding between the Cu matrix and the diamond particles.
- Mechanical Enhancement: B addition significantly increased the bending strength of the composite by 123% compared to B-free composites, indicating a shift from interfacial failure (debonding) to transgranular fracture of the diamond particles.
- Process Stability: The SPS process was successfully conducted at a low temperature (1173 K) and short duration (600 s) to preserve the structural integrity and high intrinsic thermal conductivity of the diamond phase.
- Relevance to Electronics: These composites offer significantly enhanced heat dissipation capabilities required for high-power, miniaturized electronic components, such as high-density LSI devices, LEDs, and EV/Hybrid motor components.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the study detailing the optimal composite composition and performance metrics.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Thermal Conductivity ($\lambda$) | 689 | W/mK | (Cu-7.2 vol% B)-50 vol% Diamond Composite |
| Baseline Thermal Conductivity ($\lambda$) | 152 | W/mK | Cu-50 vol% Diamond Composite (No B) |
| Improvement Factor | 4.53 | N/A | Increase achieved with B doping |
| Optimal Boron Volume Fraction | 7.2 | vol% in Cu matrix | Corresponds to 3.6 vol% B in the total composite |
| Thermal Boundary Conductance ($h_{c}$) (Max) | 1.80 x 107 | W/m2K | (Cu-7.2 vol% B)-50 vol% Diamond |
| Baseline $h_{c}$ (No B) | 3.59 x 103 | W/m2K | Cu-50 vol% Diamond |
| Relative Packing Density (Max) | 95.8 | % | Achieved with 13.8 vol% B |
| Relative Packing Density (Baseline) | 89.7 | % | Cu-50 vol% Diamond (No B) |
| Bending Strength Improvement | 123 | % | Relative increase (No B to 7.2 vol% B composite) |
| Diamond Particle Size (Mean) | 310 | ”m | Input material (IMS-15, Torimei Dia) |
Key Methodologies
Section titled âKey MethodologiesâThe Cu/Diamond/Boron composites were fabricated using the Spark Plasma Sintering (SPS) technique, ensuring rapid densification and diamond phase preservation.
- Material Preparation:
- Diamond particles (50 vol% fixed concentration), atomized Cu powder, and B powder were mixed.
- B concentration was varied from 0 to 13.8 vol% within the Cu matrix phase.
- A small amount of ethanol was added during mixing to prevent segregation due to density differences.
- SPS Parameters:
- Atmosphere: Vacuum (2 Pa).
- Heating Rate: 1.67 K/s.
- Maximum Sintering Temperature: 1173 K (900 °C). Note: This temperature is cited as the critical limit to prevent diamond degradation.
- Holding Time: 600 s.
- Applied Pressure: 80 MPa.
- Characterization:
- Relative density was measured using the Archimedes method.
- Microstructure and phase presence were confirmed via SEM, EDX (planned for interface analysis), and XRD. No interfacial reaction layer was conclusively identified via XRD/SEM, suggesting any reactive phase is nano-sized.
- Thermal conductivity ($\lambda$) was measured using the Laser Flash method (NETZSCH LFA-457).
- Boundary Conductance ($h_{c}$) was calculated using the measured $\lambda$ and the Hasselman-Johnson theoretical model.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe findings underscore that the primary challenge in diamond-metal composites is overcoming the high interfacial thermal resistance (low $h_{c}$). While powder metallurgy (SPS) with additives like Boron offers a solution for diamond particles, 6CCVDâs MPCVD diamond materials provide the most advanced platform for maximizing thermal performance in high-power applications by eliminating the challenges inherent in heterogeneous powder consolidation.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend the high thermal performance demonstrated in this research, 6CCVD recommends leveraging superior CVD diamond architectures combined with optimized metalization for ideal interfacial bonding.
| Material Recommendation | Grade/Type | Justification for Application |
|---|---|---|
| High Thermal Grade SCD | Optical/Electronic Grade SCD | Offers intrinsic thermal conductivity (>2000 W/mK) that surpasses the thermal limits of crushed HPHT particles used in the paper. Ideal for critical point-source heat spreaders. |
| High Quality PCD | Large Area Inch-Size PCD | Relevant for large-area substrates (up to 125mm) required for power modules and hybrid motor electronics. Provides excellent thermal dissipation capability as a stable platform. |
| Boron-Doped Diamond (BDD) | BDD Thin Film/Electrode | If Boron addition is required for enhanced bonding, 6CCVD can integrate B into the diamond structure itself, or provide BDD films as an intermediate layer for catalytic interfacial reactions. |
Customization Potential
Section titled âCustomization PotentialâThe research highlights that the integrity of the Cu/Diamond interface dictates thermal performance. 6CCVD specializes in engineering this interface directly onto high-quality CVD diamond wafers.
- Custom Metalization Stacks: The paper requires optimized bonding to a Cu matrix. 6CCVD offers in-house deposition of custom metal adhesion layers, including: Ti (known carbide former, superior to B for adhesion), W, Pt, and Au finishing layers. We can tailor the Ti/W adhesion layer thickness to minimize phonon scattering and optimize bonding strength to the metal heat sink (Cu, Mo, AlN).
- Large-Scale Integration: The research used small, 10mm diameter disks. 6CCVD fabricates inch-sized PCD plates (up to 125mm) and custom SCD plates (up to 500 ”m thickness), perfect for scalable manufacturing of advanced thermal management solutions.
- Precision Shaping and Surface Quality: We provide ultra-low roughness polishing (Ra < 1 nm for SCD, < 5 nm for PCD). Controlling the surface topography is crucial for minimizing thermal boundary resistance ($h_{c}$) in the eventual diamond-to-heat sink bond, extending the principle demonstrated in the paper to the final application stage.
Engineering Support
Section titled âEngineering SupportâThe challenges encountered in the researchâspecifically identifying the nano-sized interfacial reaction layer (suggested B-carbide) and optimizing the $h_{c}$âare directly addressed by advanced material science. 6CCVDâs in-house PhD team provides specialized consultation to material developers and technical engineers working on high-performance thermal management projects, particularly those involving demanding interfacial requirements for electronic packaging or high-frequency devices.
Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Diamond-particle-dispersed-copper (Cu) matrix composites were fabricated by spark plasma sintering (SPS) process from the mixture of diamond particles, pure-Cu and boron (B) powders. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated at a temperature of 1173 K for 600 s by spark plasma sintering (SPS) process. No reaction at the interface between the diamond particle and the Cu matrix was observed by scanning electron microscopy and X-ray diffraction analysis for the composites fabricated under the sintering condition employed in the present study. The relative packing density of the diamond particle dispersed Cu matrix composites with B addition was 3.56.1 % higher than that without B addition. The thermal conductivity of the Cu/diamond composite drastically increased with B addition. The thermal conductivity of (Cu-B)-50 vol% diamond composites was 594689 W/mK in a volume fraction range of B between 1.8 and 13.8 vol% in Cu matrix. Numerous transgranular fractures of diamond particles were observed on the bending fracture surface of diamond particle dispersed Cu matrix composites with B addition, indicating strong bonding between the diamond particle and the Cu matrix in the composite.