Fabrication of high thermal conductivity copper/diamond composites by electrodeposition under potentiostatic conditions
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-03-09 |
| Journal | Journal of Applied Electrochemistry |
| Authors | Susumu Arai, Miyoka Ueda |
| Institutions | Shinshu University |
| Citations | 19 |
| Analysis | Full AI Review Included |
Fabrication of High Thermal Conductivity Cu/Diamond Composites
Section titled âFabrication of High Thermal Conductivity Cu/Diamond CompositesâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates a novel, low-temperature electrodeposition method for fabricating high thermal conductivity copper/diamond composites, overcoming critical limitations of traditional methods.
- Record Thermal Performance: Composites achieved a maximum thermal conductivity of 600 W m-1 K-1, representing a 1.5-fold increase over the pure copper matrix (ca. 400 W m-1 K-1).
- Process Innovation: The key advancement is the use of potentiostatic conditions for copper electrodeposition, replacing conventional galvanostatic methods.
- Hydrogen Evolution Mitigation: Potentiostatic control, specifically setting the potential to 0.0412 V vs. SHE, completely suppressed hydrogen gas evolution, which previously disrupted the arrangement of diamond particles.
- Dense Morphology: The resulting composites exhibited compact, dense microstructures with no observable gaps or cracks between the copper matrix and the precipitated diamond particles, ensuring high interfacial thermal conductance.
- Ambient Fabrication: The technique operates at ambient temperature and pressure, offering a cost-effective and simplified alternative to high-temperature sintering or infiltration methods.
- Optimal Composition: The highest performance was achieved using 49 vol% of the largest tested diamond particles (230 ”m mean diameter).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Measured Thermal Conductivity (λ) | 600 | W m-1 K-1 | Composite with 49 vol% 230 ”m diamond. |
| Pure Copper Thermal Conductivity (λ) | ca. 400 | W m-1 K-1 | Baseline comparison. |
| Optimal Diamond Volume Fraction (Vdia) | 49 | vol% | Achieved highest λ with 230 ”m particles. |
| Optimal Diamond Particle Size | 230 | ”m | Range tested: 10, 25, 45, 230 ”m. |
| Potentiostatic Deposition Potential (SHE) | 0.0412 | V vs. SHE | Set to prevent H2 evolution. |
| Potentiostatic Deposition Potential (SCE) | -0.200 | V vs. SCE | Equivalent operational potential. |
| Estimated Current Density (Potentiostatic) | ca. -55 | mA cm-2 | Current density during controlled deposition. |
| Galvanostatic Current Density (Substrate w/o Diamond) | 5 | mA cm-2 | Baseline current density for comparison. |
| Galvanostatic Current Density (Substrate w/ Diamond Monolayer) | Up to 50 | mA cm-2 | 10x higher than baseline, risking H2 evolution. |
| Copper Sulfate Concentration | 0.85 | M | CuSO4·5H2O in plating bath. |
| Sulfuric Acid Concentration | 0.55 | M | H2SO4 in plating bath. |
| Copper Density (ÏCu) | 8.94 | g dm-3 | Used for composite density calculation. |
| Diamond Density (Ïdia) | 3.52 | g dm-3 | Used for composite density calculation. |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication process relies on a two-step electrodeposition technique utilizing a horizontal electrode setup to ensure stable particle arrangement.
- Electrode Configuration: A pure copper plate cathode (18 cm2) was positioned horizontally at the bottom of the plating bath, allowing diamond particles to settle via gravity. A phosphorus-containing copper plate served as the anode.
- Diamond Precipitation: Commercially available single-crystal diamond particles (10-230 ”m) were added to the bath, dispersed, and then allowed to precipitate onto the cathode surface, forming stable monolayer or bilayer structures.
- Electrolyte Preparation: The plating bath consisted of an aqueous solution containing 0.85 M CuSO4·5H2O and 0.55 M H2SO4.
- Process Control Transition: Initial electrochemical investigations confirmed that galvanostatic conditions led to high current densities (up to 10 times higher than the baseline) and subsequent undesired hydrogen evolution.
- Potentiostatic Deposition: Copper electrodeposition was performed under strict potentiostatic control, setting the potential to 0.0412 V vs. SHE (-0.200 V vs. SCE). This potential ensures the deposition proceeds primarily via charge transfer kinetics without triggering hydrogen evolution.
- Composite Formation: The deposited copper matrix filled the gaps between the precipitated diamond particles and the substrate, resulting in a dense, gap-free Cu/diamond composite structure.
- Characterization: Thermal diffusivity (a) was measured using a xenon laser flash analyzer. Thermal conductivity (λ) was calculated using the relationship: λcomp = a · Ïcomp · Ccomp, where Ï and C are the calculated density and specific heat capacity of the composite.
Commercial Applications
Section titled âCommercial ApplicationsâThe ability to produce high-performance thermal management materials at ambient conditions makes this technology highly relevant for several high-power density applications.
- High-Power Electronics & Microprocessors:
- Fabrication of integrated heat spreaders (IHS) and thermal vias for advanced CPUs, GPUs, and memory modules requiring rapid heat removal.
- Substrates for high-frequency and high-power RF devices (e.g., 5G infrastructure).
- Electric Vehicle (EV) and Hybrid Systems:
- Thermal management components for power inverter modules, battery cooling systems, and motor controllers where weight and thermal efficiency are critical.
- Solid-State Lighting and Lasers:
- Manufacturing of highly conductive submounts and packaging materials for high-brightness LEDs and high-power laser diodes to maintain operational stability and lifetime.
- Aerospace and Defense:
- Production of lightweight, high-performance thermal components for avionics and radar systems that must operate reliably under extreme thermal loads.
- Advanced Manufacturing:
- The electrodeposition technique allows for conformal coating and fabrication of complex geometries, enabling integration into micro-scale devices and 3D structures where traditional sintering is impractical.
View Original Abstract
Abstract High thermal conductivity Cu/diamond composites were fabricated using an electrodeposition technique. The electrodes were oriented horizontally, and the cathode was located at the bottom of the plating bath. Diamond particles (10-230 ÎŒm) were first precipitated on the cathode substrate, and then copper was electrodeposited on the substrate to fill the gap between the precipitated diamond particles, which resulted in the formation of a Cu/diamond composite. The deposition behavior of the copper was electrochemically investigated, and the current densities of copper deposition under galvanostatic conditions were estimated. The current densities for the substrate with diamond particle layers were 4-10 times higher than the current density for the substrate without diamond particle layers, which led to undesired hydrogen evolution. Cu/diamond composites were formed under potentiostatic conditions without hydrogen evolution, and the resultant composites had compact morphologies. A specimen containing 49 vol% diamond particles with a mean diameter of 230 ÎŒm had the highest thermal conductivity of 600 W m â1 K â1 , which is 1.5 times that of pure copper (ca. 400 W m â1 K â1 ). Graphic Abstract High thermal conductivity Cu/diamond composites were fabricated by electrodeposition under a potentiostatic condition without the evolution of hydrogen gas.