Manufacturability of A20X printed lattice heat sinks

At a Glance

Metadata	Details
Publication Date	2024-12-20
Journal	Progress in Additive Manufacturing
Authors	Ganesh Chouhan, Prveen Bidare
Institutions	Sheffield Hallam University
Citations	4
Analysis	Full AI Review Included

Technical Analysis and Documentation: High-Performance Thermal Management using MPCVD Diamond

Executive Summary

This research successfully demonstrates the manufacturability of compact, high-surface-area Triply Periodic Minimal Surface (TPMS) lattice heat sinks using Laser Powder Bed Fusion (LPBF) with A20X aluminum alloy. While the study validates the geometric complexity achievable via Additive Manufacturing (AM), it highlights critical limitations that 6CCVD’s MPCVD diamond materials directly address:

High Surface Area Achieved: TPMS lattices (Gyroid, Diamond, Split P) achieved surface areas up to 5698.24 mm² within a 15x15x15 mm³ volume, significantly exceeding conventional pin fins.
Material Limitation: A20X aluminum, while strong, possesses thermal conductivity orders of magnitude lower than CVD diamond, limiting ultimate heat dissipation capacity required for high-power electronics.
Surface Quality Deficiencies: LPBF resulted in highly variable surface roughness (Ra ranging from 0.367 µm to 3.46 µm) and numerous defects (voids, balling, partially melted particles), which negatively impact heat transfer efficiency and structural integrity.
6CCVD Solution: Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) offer the highest known thermal conductivity (up to 2000 W/mK), enabling superior heat spreading and dissipation compared to A20X.
Precision Polishing Advantage: 6CCVD provides ultra-low roughness polishing (Ra < 1nm for SCD, < 5nm for PCD), eliminating the surface irregularities and defects observed in the LPBF metal samples, thereby minimizing thermal boundary resistance (TBR).

Technical Specifications

The following table summarizes key data extracted from the research paper regarding the A20X LPBF process and resulting heat sink characteristics.

Parameter	Value	Unit	Context
Target Heat Sink Volume	15 x 15 x 15	mm³	Fixed volume for TPMS comparison
Maximum Surface Area (SA)	5698.24	mm²	Split P UC-5 lattice design
Minimum Surface Roughness (Ra)	0.3672	µm	Diamond UC-10 lattice (Smoothest result)
Maximum Surface Roughness (Ra)	3.4602	µm	Diamond CSUC-10 lattice (Rougest result)
Relative Density (A20X)	> 99.5	%	Achieved via LPBF
Unit Cell Sizes Tested	5 and 10	mm	TPMS lattice periodicity
A20X Powder Size Range	20-60	µm	Gas-atomized, spherical
LPBF Laser Power	200	W	Optimized process parameter
LPBF Layer Thickness	30	µm	Z-increment (contributes to stair-casing)
A20X Tensile Strength	~400	MPa	High-strength aluminum alloy

Key Methodologies

The study focused on the manufacturability and surface quality of TPMS heat sinks using optimized LPBF parameters for A20X aluminum.

Design Generation: Five TPMS lattice types (Gyroid, Diamond, Lidinoid, Schwarz P, Split P) were designed using level-set approximation equations and nTopology implicit modeling software.
Material Preparation: Spherical, gas-atomized A20X aluminum powder (20-60 µm particle size) enhanced with titanium diboride (TiB₂) doping was used as feedstock.
Additive Manufacturing (AM): LPBF was performed using a Concept Laser M2 system.
- Atmosphere: Argon, maintaining oxygen content at < 0.1%.
- Key Parameters: Laser power 200 W, scan speed 1450 mm/s, layer thickness 30 µm.
- Build Orientation: All samples printed with a 90° build orientation.
Microstructural Analysis: Scanning Electron Microscopy (SEM) (Hitachi TM3030, Jeol JSM-6060) was used to examine microstructural deterioration, defects (voids, balling, unmelted particles), and surface morphology.
Surface Topography Analysis: High-resolution 3D surface topography was measured using an optical non-contact profilometer (Alicona InfiniteFocus [IF-G4]) to quantify roughness parameters (Ra, Rq, Rz).

6CCVD Solutions & Capabilities

The research confirms that complex, high-surface-area structures are essential for next-generation thermal management. However, the use of A20X aluminum limits the ultimate thermal performance. 6CCVD provides the necessary materials and precision engineering to achieve maximum heat dissipation in compact, high-power density applications.

Applicable Materials for Thermal Enhancement

To replicate or significantly extend this research into high-performance thermal management, 6CCVD recommends the following MPCVD diamond materials:

6CCVD Material	Key Advantage	Application Relevance
Optical Grade SCD	Highest Thermal Conductivity (k > 2000 W/mK).	Ideal for micro-scale heat spreaders, laser diodes, and high-flux electronic devices where maximum heat removal is critical.
High Thermal Grade PCD	Excellent k (up to 1800 W/mK) and larger area capability.	Suitable for larger heat sink plates (up to 125mm diameter) or substrates requiring high thermal performance across a broader area.
Boron-Doped Diamond (BDD)	Electrically conductive and thermally stable.	If the TPMS lattice were adapted for electrochemical or sensing applications requiring both thermal management and electrical access.

Customization Potential & Precision Engineering

The LPBF process resulted in significant surface roughness (Ra up to 3.46 µm) and defects, which severely compromise the thermal interface quality. 6CCVD’s capabilities overcome these limitations:

Ultra-Low Roughness Polishing:
- The paper’s smoothest result was Ra 0.367 µm. 6CCVD routinely achieves Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD. This superior surface finish is crucial for minimizing Thermal Boundary Resistance (TBR) when bonding the heat sink to a chip or substrate.
Custom Dimensions and Thickness:
- While the paper focused on 15 mm³ samples, 6CCVD offers custom plates and wafers up to 125 mm in diameter (PCD).
- We provide SCD and PCD layers in the critical thickness range (0.1 µm to 500 µm) necessary for effective heat spreading in compact devices.
Integrated Metalization Services:
- For robust integration into electronic systems, 6CCVD provides in-house metalization (Au, Pt, Pd, Ti, W, Cu) tailored to specific bonding requirements, ensuring reliable thermal and mechanical interfaces.
Advanced Fabrication:
- 6CCVD utilizes precision laser cutting and etching techniques, allowing for the creation of intricate geometries and features (such as microchannels or mounting holes) with far greater dimensional accuracy than the LPBF defects reported in the study.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing diamond material properties for extreme environments and high-flux thermal applications. We can assist researchers and engineers in translating the geometric advantages of TPMS lattice designs (like Gyroid or Diamond structures) onto diamond substrates, ensuring optimal material selection and interface preparation for compact, high-power density thermal management projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Original Source

DOI: https://doi.org/10.1007/s40964-024-00923-3