Geometry-Programmable Heat Routing via Shear-Aligned BNNT/Epoxy Composites: From Passive Spreading to Directed Guiding

초록

Miniaturization and rising power densities exacerbate localized hot spots on electrically insulating substrates, where heat spreadsnon-selectively. A boron nitride nanotube (BNNT)/epoxy “thermal guide” is developed for selective, geometry-programmable heatrouting. A viscosity-tuned BNNT/epoxy ink is processed by micro-nozzle extrusion; confinement-induced shear aligns BNNTs intoan orientation-defined architecture, as confirmed by small-angle X-ray scattering and supported by flow simulations identifyingnozzle size as a key alignment control. Aligned bulk composites exhibit pronounced in-plane anisotropy (ky /kx ≈ 2.53; 2.96 vs 1.17 Wm− 1 K− 1 , parallel vs transverse to the fiber direction), and infrared thermography visualizes alignment-guided heat transport: at5 cm from a 70◦C source, the y-axis-oriented specimen reaches 55.8◦C after 30 s, compared with 48.1◦C for the x-axis-orientedspecimen. Dielectric integrity is retained at network-forming loadings, with volume resistivity of ∼10 13 Ω⋅m at 20 wt.% BNNT andlow dielectric loss. Dispenser printing enables ∼200 µm-wide guides; contacting a 70◦C source at the guide terminus produces>20◦C terminal contrast relative to the surrounding region outside the printed pattern. This method therefore enables electricallysafe thermal routing to guide heat from a localized source to a target region while suppressing parasitic lateral diffusion intoheat-sensitive areas

키워드