Fabrication, Microstructure, Thermal and Electrical Properties of Copper Heat Sink Composites
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-01-01 |
| Journal | Materials Sciences and Applications |
| Authors | Walid M. Daoush, Ahmed Swidan, Gamal Abd El-Aziz, Mohamed Anwar K Abdelhalim |
| Institutions | Suez University, Helwan University |
| Citations | 7 |
| Analysis | Full AI Review Included |
Technical Analysis: Diamond-Reinforced Copper Composites for High-Performance Heat Sinks
Section titled âTechnical Analysis: Diamond-Reinforced Copper Composites for High-Performance Heat SinksâThis document analyzes the research paper âFabrication, Microstructure, Thermal and Electrical Properties of Copper Heat Sink Compositesâ to highlight key findings relevant to advanced thermal management and to position 6CCVDâs MPCVD diamond capabilities as the optimal solution for replicating and advancing this research.
Executive Summary
Section titled âExecutive Summaryâ- Superior Thermal Performance: The 1 wt% Cu/Diamond composite achieved the highest thermal conductivity (TC) of all tested materials at 405 W/m·K, representing a 3.5% increase over pure sintered copper (398 W/m·K).
- Interface Challenge Identified: The primary limitation for uncoated diamond composites was the weak interfacial bonding and high thermal barrier resistance between the chemically inert diamond particles and the copper matrix.
- Methodology: Composites were fabricated using Powder Metallurgy (PM), involving cold compaction at 600 MPa followed by sintering at 1173 K (900°C) for 2 hours under a hydrogen/nitrogen atmosphere.
- Coating Success: Electroless deposition coating (Ag or Cu) on other reinforcement particles (Graphite, Carbon Fiber) significantly improved particle distribution, density (up to 96% relative density), and reduced electrical resistivity by enhancing matrix-reinforcement wettability.
- Electrical Resistivity Trade-off: While diamond provided the highest TC, the Cu/Diamond composite exhibited the highest electrical resistivity (50 ”Ω·m) among the tested materials, underscoring the need for advanced interfacial engineering to simultaneously optimize both thermal and electrical properties.
- Application Suitability: The resulting composites are confirmed to be highly suitable for high-power electronic heat sink applications requiring superior heat dissipation.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the critical material properties and processing parameters extracted from the study, focusing on the diamond composite and key fabrication metrics.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Peak Thermal Conductivity (Cu/Di) | 405 | W/m·K | 1 wt% Diamond composite |
| Pure Cu Thermal Conductivity | 398 | W/m·K | Sintered reference sample |
| Cu/Di Electrical Resistivity | 50 | ”Ω·m | Highest resistivity among tested composites |
| Cu/Gr Coated Ag Electrical Resistivity | 10 | ”Ω·m | Lowest resistivity among tested composites |
| Diamond Particle Size | < 1 | ”m | Starting reinforcement material |
| Copper Powder Particle Size | 44 | ”m | High purity electrolytic Cu (99.9%) |
| Cold Compaction Pressure | 600 | MPa | Uniaxial die compaction |
| Sintering Temperature | 1173 (900) | K (°C) | Held for 120 minutes |
| Sintering Atmosphere | H2/N2 | Gas Mixture | Reducing atmosphere |
| Relative Sintered Density (Max) | 96 | % | Achieved by coated composites |
| Thermal Test Temperature Range | 323 to 393 | K | 50°C to 120°C |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication process relied on Powder Metallurgy (PM) combined with advanced surface treatment to manage the interface between the copper matrix and the reinforcement particles.
- Material Preparation: High purity electrolytic copper powder (44 ”m) was mixed with 1 wt% reinforcement (diamond, graphite, or short carbon fiber, Di size < 1 ”m).
- Surface Pretreatment: Reinforcement particles underwent aggressive chemical cleaning using 67% nitric acid and 50% sodium hydroxide, followed by acetone to remove organic impurities and etch the surface.
- Electroless Deposition: Selected particles (Graphite, Carbon Fiber) were coated via electroless deposition. Graphite received a Silver (Ag) layer using silver nitrate/formaldehyde. Carbon fiber received a Copper (Cu) layer using a bath containing Copper Sulphate (35 g/l) and Potassium Sodium Tartrate (170 g/l) at 25°C.
- Consolidation: Powders were cold compacted at 600 MPa into green compacts (50 mm diameter).
- Sintering Cycle: Compacts were sintered in a hydrogen/nitrogen atmosphere, following a cycle including 30 minutes of drying, 30 minutes of degassing, and 120 minutes of sintering at 1173 K (900°C).
- Characterization: Properties were measured using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrometer (EDS), Archimedes method for density, four-probe method for electrical resistivity, and a conduction method (Fourier formula) for thermal conductivity.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research confirms that diamond is the optimal reinforcement for high-TC copper heat sinks, but its performance is critically limited by the Cu-Diamond interface. 6CCVDâs expertise in MPCVD diamond material science and advanced metalization directly addresses this challenge, enabling the production of next-generation thermal management solutions.
| Research Requirement / Challenge | 6CCVD Solution & Value Proposition |
|---|---|
| High Thermal Conductivity Diamond | SCD/PCD Material Expertise: 6CCVD specializes in producing high-purity Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) wafers. Our deep understanding of diamond crystal structure and thermal properties is essential for selecting the optimal diamond phase (powder or plate) for any Metal Matrix Composite (MMC) application. |
| Interface Thermal Barrier Resistance | Advanced Metalization Stacks: The paper noted that simple Ag or Cu coatings improved bonding. 6CCVD offers sophisticated, in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu). We can apply reactive metal layers (e.g., Ti or W) via sputtering to the diamond surface to form stable carbides, ensuring superior chemical bonding and drastically reducing the interfacial thermal resistance (ITR) between the diamond and the copper matrix. |
| Custom Dimensions for Heat Sinks | Large Area PCD Wafers: 6CCVD manufactures large-format PCD plates up to 125mm in diameter. For applications requiring large heat spreaders or substrates, our MPCVD PCD offers superior thermal performance and mechanical stability compared to PM compacts. |
| Applicable Materials | Optical Grade SCD or High-Purity PCD: For high-end thermal management where the diamond is used as a substrate or spreader, our SCD (thickness 0.1”m - 500”m) or PCD (up to 125mm diameter) provides intrinsic thermal conductivity far exceeding the 405 W/m·K achieved by the 1 wt% composite. |
| Surface Quality Requirement | Ultra-Low Roughness Polishing: 6CCVD achieves surface roughness (Ra) < 1nm for SCD and < 5nm for inch-size PCD. This ultra-smooth surface is crucial for minimizing air gaps and maximizing physical contact when bonding diamond plates to metal heat sinks, directly solving the âair layerâ problem noted in the paper. |
| Engineering Support | In-House PhD Team Consultation: Our material scientists can assist engineers in designing the optimal diamond-metal interface for similar Cu/Diamond Heat Sink projects, focusing on maximizing TC while maintaining low electrical resistivity through tailored metal bonding layers. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. Global shipping (DDU default, DDP available) is provided for all custom orders.
View Original Abstract
Copper as well as copper base composites reinforced with coated and uncoated 1 wt% diamond, graphite particles or short carbon fibers are prepared by powder metallurgy process. The reinforcement particles were encapsulated with silver as well as copper layer by using the electroless deposition technique to investigate the influence of the reinforcement surface coating on the microstructure, density, electrical and thermal properties of the sintered samples. The coated and the uncoated powders were cold compacted at 600 MPa, and then sintered at 1173 K (900°C) for 2 h under hydrogen atmosphere. The phase composition, morphology and microstructure of the prepared powders as well as the copper base sintered composites were investigated using X-ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS) respectively. The density of the sintered composites was measured by Archimedes method. The copper base consolidated composites had a density up to 96% and the reinforcement coated particles were distributed uniformly within the copper matrix better than the uncoated one. The electrical resistivity at room temperature and the heat transfer conduction of the produced samples were measured in a temperature range between 323 K (50°C) and 393 K (120°C). The results observed that the sintered materials prepared from the coated powder have lower electrical resistivity than the sintered materials prepared from the mixed powders. On the other hand the thermal conductivity values were calculated using the heat transfer conduction values by means of the Fourier formula. The results observed that the thermal conductivity of copper is (391 W/m·K), 1 wt% diamond/Cu is (408 W/m·K), 1 wt% graphite coated silver/Cu is (393 W/m·K), 1 wt% Cu coated short carbon fiber/Cu is (393 W/m·K), graphite/Cu is (383 W/m·K) and short carbon fiber/Cu is (382 W/m·K). The obtained composites are expected to be suitable for heat sink applications. The heat transfer testing experiments were done. The forced convection of the present work was done and compared with the previous work in the literature, and satisfactory agreement was achieved.