Molecular dynamics simulation of thermal conductivity of diamond/epoxy resin composites
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2023-01-01 |
| Journal | Acta Physica Sinica |
| Authors | Xiucheng Liu, Zhi Yang, Hao Guo, Ying Chen, Xianglong Luo |
| Institutions | Chinese Academy of Sciences, Technical Institute of Physics and Chemistry |
| Citations | 5 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond/Epoxy Resin Composites
Section titled āTechnical Documentation & Analysis: Diamond/Epoxy Resin CompositesāExecutive Summary
Section titled āExecutive SummaryāThis analysis summarizes the molecular dynamics (MD) simulation of nano-diamond (ND) filled epoxy resin (EP) composites, focusing on optimizing thermal conductivity (TC) for high-flux microelectronic thermal interface materials (TIMs).
- Application Focus: Addresses critical heat dissipation challenges in next-generation 5G and high-power microelectronic chips.
- Core Mechanism: Utilized Non-Equilibrium Molecular Dynamics (NEMD) to investigate the effects of filler size and particle number on composite TC.
- Matrix Optimization: Confirmed that increasing the epoxy crosslinking rate to 90% significantly boosts the matrix TC, achieving 0.23 WĀ·mā»Ā¹Ā·Kā»Ā¹ (a 77% increase over 0% crosslinking).
- Optimal Filling Strategy: Single-particle filling with larger ND fillers (2 nm radius, 26.15% mass fraction) yielded the maximum simulated TC of 0.592 WĀ·mā»Ā¹Ā·Kā»Ā¹, representing a 2.52x improvement over pure EP.
- Key Finding (Size vs. Number): Filler particle size is a more critical factor than particle number for TC enhancement. Larger particles reduce the fractional free volume (FFV) and minimize the detrimental effects of interfacial thermal resistance (ITR) associated with high surface area multi-particle packing.
- Interfacial Resistance: Multi-particle filling leads to a larger specific surface area and increased ITR, which significantly weakens the overall TC improvement, despite reducing FFV.
Technical Specifications
Section titled āTechnical SpecificationsāThe following hard data points were extracted from the MD simulation results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Pure Epoxy TC (90% Crosslinking) | 0.23 | WĀ·mā»Ā¹Ā·Kā»Ā¹ | Simulated TC of the matrix material |
| Max Composite TC Achieved | 0.592 | WĀ·mā»Ā¹Ā·Kā»Ā¹ | Single 2 nm ND particle, 26.15% mass fraction |
| TC Enhancement Factor | 2.52 | Times | Relative to pure epoxy TC |
| Intrinsic Diamond TC (Reference) | 2000 | WĀ·mā»Ā¹Ā·Kā»Ā¹ | High thermal conductivity of bulk diamond |
| Diamond Electrical Resistivity (Reference) | 1000 | Ī©Ā·cm | Low electrical conductivity of diamond |
| Optimal Crosslinking Rate | 90.00 | % | Used for all composite simulations |
| Simulation Temperature (NPT/NVT) | 300 | K | Standard operating temperature |
| Simulation Pressure (NPT) | 1.01 x 10āµ | Pa | Standard atmospheric pressure |
| ND Particle Size Range (Single Fill) | 1.0 to 2.0 | nm | Varied to study size effect |
| Max ND Mass Fraction Tested | 30.38 | % | Multi-particle filling (10 particles, 1 nm size) |
| Minimum Free Volume Fraction | 3.71 | % | Achieved at 30.38% mass fraction (10 particles) |
| Simulation Time Step | 0.25 | fs | NEMD calculation step length |
Key Methodologies
Section titled āKey MethodologiesāThe thermal conductivity of the diamond/epoxy composites was investigated using the Non-Equilibrium Molecular Dynamics (NEMD) method, implemented on the LAMMPS platform.
- Model Construction: Epoxy resin (DGEBF) and curing agent (DETDA) were mixed at a 2:1 ratio. Nano-diamond (ND) particles (1.0 nm to 2.0 nm radius) were incorporated.
- Surface Treatment: The surface carbon atoms of the ND particles were treated with hydrogen termination to ensure electrical neutrality and simulate realistic filler interfaces.
- Crosslinking Simulation: The crosslinking reaction was performed at 600 K, targeting a final crosslinking rate of 90.00%.
- Equilibration: Models were structurally optimized using the Smart Minimizer algorithm, followed by relaxation in the NVT (300 K) and NPT (300 K, 1.01 x 10āµ Pa) ensembles for 100 ps each to achieve stable density.
- Force Fields: The interactions were modeled using the PCFF force field (epoxy matrix), the Tersoff potential (diamond C-C bonds), and the Lennard-Jones 12-6 potential (interfacial interactions).
- NEMD Setup: The simulation box was divided into 20 equal bins. A temperature gradient was established using the local heat bath method, setting the hot region (Bin 1) to 330 K and the cold region (Bin N/2+1) to 270 K.
- Data Collection: After stabilization in the NVE ensemble (500 ps), equilibrium calculations were performed for 2500 ps to statistically sample the heat flow and temperature gradient, allowing TC calculation via the Fourier law.
6CCVD Solutions & Capabilities
Section titled ā6CCVD Solutions & Capabilitiesā6CCVD specializes in providing high-purity, high-quality MPCVD diamond materials essential for replicating and extending this research into practical, high-performance thermal management solutions. The simulation results underscore the critical role of filler quality, size, and interface engineeringāareas where 6CCVD excels.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage & Sales Proposition |
|---|---|---|
| High-Purity Diamond Filler (Intrinsic TC of 2000 WĀ·mā»Ā¹Ā·Kā»Ā¹) | Polycrystalline Diamond (PCD) Powder/Substrates | 6CCVD supplies high-purity MPCVD PCD, which maintains the low defect density necessary to achieve maximum intrinsic thermal conductivity, far superior to lower-grade diamond materials. |
| Precise Dimensional Control (Optimizing filler size/geometry) | Custom Dimensions & Laser Processing | We provide PCD plates up to 125mm and SCD substrates up to 10mm thick. For TIM applications, we offer custom grinding and laser cutting services to produce specific micron-scale fillers or precisely shaped heat spreaders, ensuring optimal geometry for low ITR. |
| Interfacial Thermal Resistance (ITR) Mitigation (Critical limitation identified in MD) | Advanced Metalization Services | 6CCVD offers in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu). Custom metal layers are essential for optimizing the phonon coupling (VDOS matching) between the diamond surface and the polymer matrix, directly addressing the ITR challenge highlighted by the multi-particle simulation. |
| High-Flux Heat Spreading (Beyond TIMs) | Optical Grade Single Crystal Diamond (SCD) | For applications requiring TC far exceeding 0.6 WĀ·mā»Ā¹Ā·Kā»Ā¹, 6CCVD provides SCD films (0.1 Āµm to 500 Āµm) and substrates with ultra-low surface roughness (Ra < 1 nm), ideal for direct integration as high-performance heat spreaders in GaN or SiC devices. |
| Material Quality & Consistency | Expert Polishing and Quality Control | Our PCD wafers are polished to Ra < 5 nm (inch-size), ensuring consistent surface quality critical for reliable interface bonding and minimizing scattering losses in both composite and direct heat spreader applications. |
| Global Supply Chain | Global Shipping (DDU/DDP) | We ensure reliable, timely delivery of custom diamond materials worldwide, simplifying procurement for international research teams. |
6CCVDās in-house PhD team specializes in material selection and interface engineering for advanced thermal management and high-power electronics projects. We can assist researchers in transitioning from MD simulation results to practical material specifications.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Improving the thermal conductivity (TC) of epoxy resin thermal interface material is of great significance in tackling the heat dissipation problem of high heat flux in microelectronic chips such as 5G. Using non-equilibrium molecular dynamics (MD) method, the effects of two different filling styles of nano-diamond fillers on the TC of EP based composites are investigated. The results show that the TC of the composite increases with the diamond size when single-particle filling is used, and that a larger diamond size leads to a more significant reduction of the free volume fraction and thus an improvement of the TC. In the multi-particle packing, the composite TC first increases and then decreases with increasing particle number. Increasing the number of particles reduces the free volume fraction, but also results in a larger specific surface area and interfacial thermal resistance, which has a more significant weakening effect on the TC. Moreover, within the same mass fraction of nano-diamond filler, increasing the filler size has a more significant TC improvement on the composite than increasing the number of particles. This study is instructive for the design and preparation of high thermal conductivity nanodiamond/epoxy resin composites.