Through-plane orientation engineering of carbon fibers for thermal interface materials

The rapid expansion of artificial intelligence and big data technologies is accelerating the development of highly integrated electronic devices, where increasing power density and localized heat flux have made through-plane thermal management a critical challenge. Thermal interface materials (TIMs) with high through-plane thermal conductivity (κ ⊥ ) and low contact thermal resistance are essential for efficient heat dissipation between chips and heat sinks. Carbon-fiber (CF) based TIMs offer a promising route for efficient thickness-direction heat dissipation because of the high axial thermal conductivity and structural reinforcement. In this review we summarize the current state of CF-based through-plane TIMs, focusing on intrinsic heat transport, interfacial engineering, and vertical orientation construction. The structural differences between polyacrylonitrile-based CFs (PAN-CFs) and pitch-based CFs (pitch-CFs) are first discussed to clarify the origin of high axial thermal conductivity. Surface modification strategies are then reviewed for their roles in improving matrix wetting, reducing interfacial thermal resistance, and maintaining cross-interface heat-flow continuity. Recent advances in magnetic-field-assisted alignment, electric-field-assisted alignment, flow-field-induced alignment, and template-assisted construction are further discussed as key routes for building vertically oriented CF architectures. Finally, we outline the remaining challenges and future opportunities in small bond-line thickness (BLT) orientation construction, interfacial thermal-resistance control, multi-field processing, and long-term service stability.