DIW-Printed Thermal Management PDMS Composites with 3D Structural Thermal Conductive Network of h-BN Platelets and Al2O3 Nanoparticles

Abstract

Electronic devices play an increasingly vital role in modern society, and heat accumulation is a major concern during device development, which causes strong market demand for thermal conductivity materials and components. In this paper, a novel thermal conductive material consisting of polydimethylsiloxane (PDMS) and a binary filler system of h-BN platelets and Al₂O₃ nanoparticles was successfully fabricated using direct ink writing (DIW) 3D printing technology. The addictive manufacturing process not only endows the DIW-printed composites with various geometries but also promotes the construction of a 3D structural thermal conductive network through the shearing force during the printing process. Moreover, the integrity of the thermal conductive network can be optimized by filling the gaps between the BN platelets with Al₂O₃ particles. Resultingly, the configuration of the binary fillers is arranged by the shearing force during the DIW process, fabricating the thermal conductive network of oriented fillers. The DIW-printed BN/Al₂O₃/PDMS with 45 wt% thermal conductive binary filler can reach a thermal conductivity of 0.98 W/(m·K), higher than the 0.62 W/(m·K) of the control sample. In this study, a novel strategy for the thermal conductive performance improvement of composites based on DIW technology is successfully verified, paving a new way for thermal management.

Keywords: Al2O3; boron nitride; thermally conductive composites; three-dimensional thermal network.

Figure 1

Schematic of the DIW ink preparation process for BN/Al₂O₃/PDMS composites.

Figure 2

Rheological properties of 40 BN/Al₂O₃, 40 BN, and 45 BN/Al₂O₃ slurries: (a) plots of slurry viscosity versus shear rate; (b) plots of modulus and shear stress of slurries; (c) plots of stress-strain relationship of slurries; (d) plots of yield stress of slurries.

Figure 3

Printing quality analysis of DIW structures: (a,c,e) the error analysis; (b,d,f) the standard deviations of size difference.

Figure 4

The SEM images of (a,b) 40 BN/Al₂O₃; (c,d) 40 BN; (e,f) 45 BN/Al₂O₃.

Figure 5

EDS images of different printed parts: (a,b) 40 BN/Al₂O₃; (c,d) 40 BN; (e,f) 45 BN/Al₂O₃.

Figure 6

XRD patterns of DIW-printed 40 BN/Al₂O₃, 40 BN, and 45 BN/Al₂O₃ composites.

Figure 7

The thermal management of the DIW-printed PDMS-based composites: (a) The top surface temperature of the cylindric 40 BN/Al₂O₃, 40 BN, and 45 BN/Al₂O₃ composite where the bottom surface of these samples was deposited on a heater with a temperature of 200 °C; (b) Thermal conductivity of composite materials; (c) The heat transfer mechanism model of 45 BN/Al₂O₃ composite.

Figure 8

Electric insulation performance of 40 BN/Al₂O₃, 40 BN, and 45 BN/Al₂O₃; (a) volume resistivity; (b) conductivity; (c) dielectric constant; (d) dielectric loss.

Figure 9

Mechanical properties of the PDMS-based composites (40 BN/Al₂O₃, 40 BN, 45 BN/Al₂O₃, and pure PDMS matrix): (a) tensile strength; (b) tensile elongation at break.