Heat Spreading Properties of CVD Diamond Coated Al Heat Sink
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-12-31 |
| Journal | Journal of the Korean institute of surface engineering |
| Authors | Min Young Yoon, Jong Hwan Im, Chan Hyoung Kang |
| Institutions | Tech University of Korea |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: CVD Diamond for High-Performance Heat Sinks
Section titled âTechnical Documentation & Analysis: CVD Diamond for High-Performance Heat SinksâExecutive Summary
Section titled âExecutive SummaryâThis research validates the use of Nanocrystalline Diamond (NCD) thin films, a form of Polycrystalline Diamond (PCD), as a superior heat spreading layer for high-power LED modules. The findings directly support 6CCVDâs core mission of providing advanced diamond materials for thermal management applications.
- Performance Improvement: NCD-coated Aluminum (Al) heat sinks demonstrated a significant 30% reduction in total thermal resistance (Rth) compared to conventional bare Al plates (3.88 K/W vs. 5.55 K/W).
- Temperature Reduction: The NCD layer lowered the critical Junction-to-Ambient temperature difference (ÎT) by 3.4 °C (12.1 °C vs. 15.5 °C), directly improving LED efficiency and extending device lifespan.
- Material Validation: The study successfully demonstrated the feasibility of depositing ultra-thin NCD films (approx. 300 nm) directly onto bulk Al substrates using Microwave Plasma Chemical Vapor Deposition (MPCVD).
- Methodology: Successful diamond nucleation on Al, a traditionally difficult substrate, was achieved through the application of Bias Enhanced Nucleation (BEN) using a -90 V DC bias.
- Heat Spreading: Thermal imaging confirmed that the NCD layer effectively spread heat faster and more uniformly across the substrate, reducing the size of the localized âhot spotâ on the front face of the LED module.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research, detailing the deposition parameters and measured thermal performance gains.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| NCD Film Thickness | 300 | nm | Deposited on Al plate |
| Substrate Thickness | 1 | mm | Al plate (3.5 mm diameter) |
| MPCVD Power | 1.2 | kW | Microwave power used for deposition |
| Working Pressure | 90 | Torr | Deposition environment |
| DC Bias Voltage | -90 | V | Bias Enhanced Nucleation (BEN) applied |
| CH4/Ar Ratio | 2/200 | sccm | Gas flow ratio |
| NCD Growth Rate | ~30 | nm/h | Calculated slow growth rate |
| Thermal Resistance (NCD/Al) | 3.88 | K/W | Measured via T3ster |
| Thermal Resistance (Bare Al) | 5.55 | K/W | Conventional Al heat sink |
| Junction ÎT (NCD/Al) | 12.1 | °C | Junction to Ambient temperature difference |
| Junction ÎT (Bare Al) | 15.5 | °C | Junction to Ambient temperature difference |
| LED Power Dissipation (PD) | 0.826 | W | Calculated operational power |
Key Methodologies
Section titled âKey MethodologiesâThe experiment focused on overcoming the challenge of diamond nucleation on aluminum using specialized MPCVD techniques.
- Substrate Preparation: Aluminum plates (1 mm thick) were mechanically polished to achieve a surface roughness (Ra) of < 100 nm.
- Seeding Process: Substrates were seeded by ultrasonic treatment in ethanol containing nanodiamond powder for 1 hour to create nucleation sites.
- MPCVD Setup: Films were grown in a Microwave Plasma Chemical Vapor Deposition reactor using a 1.2 kW microwave power and a working pressure of 90 Torr.
- Bias Enhanced Nucleation (BEN): A critical DC bias voltage of -90 V was applied to the substrate holder during deposition. This technique was essential for breaking the native Al oxide layer and promoting diamond nucleation on the Al surface.
- Gas Mixture: The reaction gas mixture consisted of Argon (Ar) and Methane (CH4) at a ratio of 200:2 sccm.
- Film Characterization: The resulting films were confirmed as NCD using X-ray Diffraction (XRD) and Raman Spectroscopy, identifying characteristic NCD peaks (1,150 cm-1, 1,350 cm-1, 1,580 cm-1).
- Thermal Measurement: Thermal performance was quantified using a Thermal Transient Tester (T3ster) in a still air box, following JEDEC JESD-51 standards, to determine thermal resistance (Rth) and structure function curves.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful integration of ultra-thin NCD films for high-performance thermal management aligns perfectly with 6CCVDâs advanced MPCVD capabilities. We offer materials and customization services necessary to replicate, scale, and optimize this research for commercial applications.
Applicable Materials
Section titled âApplicable MaterialsâThe research utilized Nanocrystalline Diamond (NCD), which falls under the category of Polycrystalline Diamond (PCD). 6CCVD provides high-quality PCD optimized for thermal spreading and heat sink applications:
- Thermal Grade PCD: Ideal for replicating this study. Our PCD offers high thermal conductivity (up to 70-80% of SCD, as noted in the paper) and is available in thicknesses ranging from 0.1 ”m up to 500 ”m, allowing engineers to precisely tune the thermal interface layer.
- Optical Grade SCD: For applications requiring even higher thermal conductivity (up to 2,000 W/mK, as cited in the paper) or superior surface quality (Ra < 1 nm), our Single Crystal Diamond (SCD) plates provide the ultimate thermal solution.
Customization Potential
Section titled âCustomization Potentialâ6CCVDâs in-house manufacturing capabilities directly address the specific requirements of advanced thermal integration projects like the one described:
| Research Requirement | 6CCVD Capability | Value Proposition |
|---|---|---|
| Substrate Size | Plates used were 3.5 mm diameter. | We offer custom plates/wafers up to 125 mm (inch-size PCD) for large-scale LED arrays or power electronics. |
| Thin Film Deposition | NCD film thickness was 300 nm. | We specialize in precise thickness control for both SCD and PCD films, from 0.1 ”m to 500 ”m, ensuring optimal thermal boundary conductance. |
| Surface Finish | Al substrate polished to Ra < 100 nm. | We provide superior polishing services, achieving Ra < 5 nm for inch-size PCD, minimizing thermal interface resistance. |
| Integration Stack | LED modules require complex metalization (e.g., Solder, Cu Paste, Lead Frame). | We offer internal custom metalization services (Au, Pt, Pd, Ti, W, Cu) to facilitate direct bonding and integration into complex electronic stacks. |
| Substrate Handling | The paper noted a very slow growth rate (30 nm/h) on Al. | 6CCVD has optimized MPCVD recipes for challenging substrates, potentially offering faster deposition rates and superior adhesion for similar diamond-on-metal projects. |
Engineering Support
Section titled âEngineering SupportâThe successful implementation of Bias Enhanced Nucleation (BEN) on Al is a complex process requiring deep expertise in plasma chemistry and interface engineering. 6CCVDâs in-house PhD team specializes in optimizing MPCVD parameters (pressure, power, gas ratio, DC bias) for novel applications.
We offer comprehensive engineering support for similar high-power thermal management projects, assisting clients with:
- Material selection (SCD vs. PCD vs. BDD) based on specific thermal and electrical requirements.
- Optimization of interface layers and metalization schemes to minimize thermal boundary resistance (TBR).
- Custom dimensions and laser cutting for integration into existing device architectures.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Nanocrystalline diamond(NCD) coated aluminium plates were prepared and applied as heat sinks for LED modules. NCD films were deposited on 1 mm thick Al plates for times of 2 - 10 h in a microwave plasma chemical vapor deposition reactor. Deposition parameters were the microwave power of 1.2 kW, the working pressure of 90 Torr, the <TEX>$CH_4/Ar$</TEX> gas ratio of 2/200 sccm. In order to enhance diamond nucleation, DC bias voltage of -90 V was applied to the substrate during deposition without external heating. NCD film was identified by X-ray diffraction and Raman spectroscopy. The Al plates with about 300 nm thick NCD film were attached to LED modules and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. Thermal resistance of the module with NCD/Al plate was 3.88 K/W while that with Al plate was 5.55 K/W. The smaller the thermal resistance, the better the heat emission. From structure function analysis, the differences between junction and ambient temperatures were <TEX>$12.1^{\circ}C$</TEX> for NCD/Al plate and <TEX>$15.5^{\circ}C$</TEX> for Al plate. The hot spot size of infrared images was larger on NCD/Al than Al plate for a given period of LED operation. In conclusion, NCD coated Al plate exhibited better thermal spreading performance than conventional Al heat sink.