Preparation of W-Plated Diamond and Improvement of Thermal Conductivity of Diamond-WC-Cu Composite

At a Glance

Metadata	Details
Publication Date	2021-03-07
Journal	Metals
Authors	Xulei Wang, Xinbo He, Zhiyang Xu, Xuanhui Qu
Institutions	University of Science and Technology Beijing
Citations	12
Analysis	Full AI Review Included

Technical Documentation & Analysis: W-Plated Diamond Composites for High Thermal Conductivity

This document analyzes the research paper “Preparation of W-Plated Diamond and Improvement of Thermal Conductivity of Diamond-WC-Cu Composite” to provide technical specifications and highlight how 6CCVD’s advanced MPCVD diamond materials and customization services directly support and extend this critical thermal management research.

Executive Summary

The research successfully demonstrated a high-performance diamond-copper composite for advanced thermal management applications by optimizing the interfacial layer.

High Thermal Performance: A thermal conductivity (TC) of 874 W·m^-1·K^-1 was achieved in a Diamond-WC-Cu composite (60 vol% diamond).
Interface Engineering: Tungsten (W) plating via powder covering sintering (1100 °C, 90 min) was optimized to create a dense, uniform 900 nm W coating on the diamond particles.
WC Transition Layer: During cyclic vacuum pressure infiltration (1200 °C), the W coating reacted to form a Tungsten Carbide (WC) transition layer.
Reduced Thermal Resistance: The WC layer significantly improved copper wettability and reduced the interface thermal resistance ($R_{int}$) to a calculated value of 2.11 x 10^-8 m²·K·W^-1.
Method Validation: The experimental TC value closely matched theoretical predictions from the Hasselman-Johnson (H-J) and Differential Effective Medium (DEM) models.
Application Readiness: The resulting composites, exhibiting high density (> 98%) and excellent thermal properties, are suitable for high-power electronic packaging materials.

Technical Specifications

Parameter	Value	Unit	Context
Final Thermal Conductivity (TC)	874	W·m^-1·K^-1	60 vol% Diamond-WC-Cu Composite
Interface Thermal Resistance ($R_{int}$)	2.11 x 10^-8	m²·K·W^-1	Calculated value due to WC transition layer
W Coating Thickness (Optimized)	900	nm	Achieved via powder covering sintering
Diamond Volume Fraction	60	vol%	Optimized composite composition
Relative Density (Composite)	> 98	%	Achieved via cyclic vacuum pressure infiltration
Diamond Particle Size (Average)	100	µm	Artificial single crystal diamond (140/170 mesh)
W Plating Temperature (Optimized)	1100	°C	Powder covering sintering method
Infiltration Temperature	1200	°C	Cyclic vacuum pressure infiltration process
Copper Matrix TC (Reference)	400	W·m^-1·K^-1	Pure red copper (used as matrix)
Diamond TC (Reference)	2000	W·m^-1·K^-1	Natural diamond (used as reinforced phase reference)

Key Methodologies

The successful preparation of the high-TC Diamond-WC-Cu composite relied on precise control over surface modification and infiltration parameters.

Diamond Surface Preparation:
- Cleaning: Boiling in 10 wt% NaOH aqueous solution for 15 min.
- Roughening: Boiling in 30 wt% dilute HNO₃ aqueous solution for 30 min.
Tungsten (W) Plating (Powder Covering Sintering Method):
- Precursors: Diamond particles, WO₃ powder, and W powder mixed.
- Atmosphere: Vacuum condition (4-6 Pa).
- Heating Rate: 10 °C/min.
- Optimized Recipe: Heated to 1100 °C and held for 90 min.
- Outcome: Dense, uniform W coating (900 nm) covering all crystal planes.
Preform Fabrication:
- W-plated diamond mixed with 1-2 wt% Polyvinyl Alcohol (PVA) binder.
- Diamond preform pressing pressure: 8.5 MPa (2 min hold).
- Copper powder pressing pressure: 80 MPa (5 min hold).
- Drying: 4-5 hours at 150 °C for pre-degassing.
Composite Preparation (Cyclic Vacuum Pressure Infiltration):
- System heated to 1200 °C (infiltration temperature).
- Initial pressurization: Argon gas to 0.5 MPa (10 min hold).
- Infiltration Cycle: Vacuum infiltration (ultimate vacuum maintained for 5 min) followed by circulating vacuum pressure infiltration (1 hour total).

6CCVD Solutions & Capabilities

The preparation of high-performance diamond composites for thermal management requires high-quality diamond material and precise surface engineering. 6CCVD is uniquely positioned to supply the necessary materials and customization services to replicate or advance this research.

Applicable Materials

To replicate or extend this research, high-purity diamond material is essential to ensure the maximum intrinsic thermal conductivity (up to 2000 W·m^-1·K^-1) before metalization.

Optical Grade SCD (Single Crystal Diamond): 6CCVD supplies high-purity SCD material suitable for crushing into particles (like the 100 µm particles used in the study) or for use as high-performance heat spreaders.
High-Purity PCD (Polycrystalline Diamond): For applications requiring larger surface areas or direct heat sink integration, 6CCVD offers PCD plates up to 125 mm diameter, which can also be customized with metalization layers.

Customization Potential

The success of this study hinges on the precise application and control of the Tungsten (W) coating thickness (900 nm) to form the critical WC transition layer. 6CCVD offers direct support for this critical step.

Requirement from Paper	6CCVD Customization Service	Relevance to Research
W Coating (900 nm)	Custom Metalization: In-house capability to deposit W, Ti, Pt, Au, Pd, or Cu layers via advanced techniques.	Allows researchers to precisely control the thickness and composition of the carbide-forming element, optimizing the interface thermal resistance ($R_{int}$).
Unique Dimensions	Custom Dimensions: Plates/wafers up to 125 mm (PCD) and substrates up to 10 mm thick.	Enables scaling the composite application from particle-based research to large-area electronic packaging solutions.
Surface Quality	Precision Polishing: SCD surfaces polished to Ra < 1 nm; PCD surfaces polished to Ra < 5 nm.	Ensures minimal thermal boundary resistance when bonding the final composite structure to active electronic components.

Engineering Support

6CCVD’s in-house PhD team specializes in diamond growth, material characterization, and interface engineering for thermal and electronic applications. We can assist clients with:

Material Selection: Choosing the optimal SCD or PCD grade based on required thermal performance and cost constraints for similar Diamond/Cu thermal management projects.
Interface Optimization: Consulting on metalization recipes (e.g., W, Ti, Cr) to achieve specific carbide transition layers and target $R_{int}$ values.
Process Integration: Providing material specifications compatible with high-temperature processes like vacuum pressure infiltration or Spark Plasma Sintering (SPS).

Call to Action

The demonstrated thermal conductivity of 874 W·m^-1·K^-1 confirms the viability of MPCVD diamond as the premier material for next-generation heat dissipation. 6CCVD provides the foundational diamond material and the necessary surface engineering expertise to push these performance boundaries further.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).

View Original Abstract

The tungsten (W)-plated diamond process was explored and optimized. A dense and uniform tungsten coating with a thickness of 900 nm was successfully prepared by the powder covering sintering method. The Diamond-WC-Cu composite with high density and high thermal conductivity were successfully prepared by cyclic vacuum pressure infiltration. The microstructure and composition of the W-plated diamond particles were analyzed. The effect of tungsten coating on the microstructure and thermal conductivity of the Diamond-WC-Cu composite was investigated. After calculation, the interface thermal resistance of the composite forming the tungsten carbide transition layer is 2.11 × 10−8 m2∙K∙W−1. The thermal conductivity average value of the Diamond-WC-Cu composite with a diamond volume fraction of 60% reaches 874 W∙m−1∙K−1, which is close to the theoretical prediction value of Hasselman-Johnson (H-J) model and differential effective medium (DEM) model. Moreover, the Maxwell-Eucken (M-E) model, H-J model, and DEM model were used to evaluate the thermal conductivity of the Diamond-WC-Cu composite.

Tech Support

Original Source

DOI: https://doi.org/10.3390/met11030437

References

2019 - High-performance epoxy/binary spherical alumina composite as underfill material for electronic packaging [Crossref]
2020 - Copper matrix thermal conductive composites with low thermal expansion for electronic packaging [Crossref]
2020 - A review on advanced carbon-based thermal interface materials for electronic devices [Crossref]
2020 - Recent advances in polymer-based electronic packaging materials [Crossref]
2018 - Recent progress in development of tungsten-copper composites: Fabrication, modification and applications [Crossref]
2015 - Comparison of W-Cu composite coatings fabricated by atmospheric and vacuum plasma spray processes [Crossref]
2011 - Review of metal matrix composites with high thermal conductivity for thermal management applications [Crossref]
2015 - Effects of rolling and annealing on microstructures and properties of Cu/Invar electronic packaging composites prepared by powder metallurgy [Crossref]
2020 - Evaluation on the interface characteristics, thermal conductivity, and annealing effect of a hot-forged Cu-Ti/diamond composite [Crossref]
2019 - Enhancing thermal conductivity of Diamond/Cu composites by regulating distribution of bimodal diamond particles [Crossref]