Thermal Conduction Path Research Articles

Effect of Diamond Morphology on Construction of Thermal Conduction Path in Flexible Thermal Interface Materials

Effect of Diamond Morphology on Construction of Thermal Conduction Path in Flexible Thermal Interface Materials

Oriented rGO framework induced hBN confined network in PDMS for absorption enhanced EMI shielding and through-plane thermal conductivity

Herein, inspired by the highly matched phonon spectra between reduced graphene oxide (rGO) and hexagonal boron nitride (hBN), and the good complementarity of the conductive loss of rGO and dielectric loss of hBN in dissipating microwaves, we construct an oriented rGO framework induced hBN confined network in bulk polydimethylsiloxane (PDMS) for electromagnetic interference (EMI) shielding and through-plane thermoconductive properties. A prefabricated three-dimensional (3D) rGO aerogel with a vertically oriented porous structure serving as an electrically conductive framework provides EMI shielding properties, and hBN distributed in the oriented rGO pores constructs a confined through-plane thermoconductive network. The introduction of hBN induces absorption-enhanced EMI shielding through dielectric loss, and the highly matched phonon spectra of rGO and hBN provide more abundant thermal conduction paths and enhance the thermal conductivity of the rGO/hBN/PDMS composites. The synergy of this rGO-hBN dual-network structure gives the composites an excellent EMI shielding effectiveness of 43.1 dB and a good through-plane thermal conductivity of 1.2 W m−1 K−1 at a thickness of 4 mm. This work provides a feasible strategy for realizing shielding and thermoconductive composites with potential applications in next-generation flexible packaging materials.

Highly thermally conductive and insulating PET nonwoven fabric/PDMS sandwich composite film by synergism of boron nitride nanosheets and alumina particles

AbstractThe accumulation of heat in electronic devices puts forward an urgent demand for thermal interface materials. It is still a great challenge to achieve the good comprehensive performance of high thermal conductivity (TC), insulation, flexibility and tensile strength. In this work, polyester‐based nonwoven fabric (NWF) was coated with boron nitride nanosheets (BNNS) by dispersion and interfacial reinforcement of cellulose nanofibers to obtain a three‐dimensional thermally conductive network skeleton (BNNS@NWF). The sandwich‐structured composite film was assembled by introducing alumina (Al2O3)/polydimethylsiloxane (PDMS) layers on the top and bottom surfaces of BNNS@NWF using scratch coating and hot pressing processes. The composite film has a high TC of 6.42 W/mK at 45.8 wt% BNNS content, and has excellent insulation with a volume resistivity of 1.06 × 1015 Ω cm. This is due to the long‐range effective thermal conduction path constructed by BNNS, the bridging effect of Al2O3 and the synergistic effect of the two fillers. PDMS helps the composite film maintain good flexibility and good TC stability after 30 bending cycles. The PET nonwoven interlayer gives the composite film good mechanical properties with a tensile strength of 17.5 MPa. This work provides a strategy for the efficient preparation of flexible composite films with high TC and insulation properties, which is of great importance for the development of innovative thermal interface materials.Highlights A sandwich‐structured composite film was prepared by a simple scale‐up method. Al2O3 and BNNS achieves synergistic enhancement of thermal conductivity. The film has a high thermal conductivity of 6.42 W/mK and electrical insulation. The film shows good flexibility, high tensile and thermal management properties.

Thermal contact conductance between additively manufactured carbon fiber reinforced thermoplastic composite: An experimental study

As the additive manufacturing provides an advanced method for fabricating polymeric composite components in thermal engineering applications, the thermal contact conductance (TCC) between the contact composites can become an important problem. In order to understand the interfacial heat transfer mechanism between thermoplastic composites, TCC between additively manufactured carbon fiber reinforced polyamide 12 (CF/PA12) composites was experimentally studied with steady-state measurements in this work. By considering the material surface microstructure, thermal and mechanical properties, the effects of interface temperature, contact pressure, surface morphology, carbon fiber (CF) content and orientation in composites on TCC were analyzed. The results show that the TCC is dependent on the actual contact area and the thermal conduction path inside the material. In general, high surface roughness decreases the TCC because of the reduction of contact area; while it is the opposite of temperature and pressure. The CF distribution affects the internal thermal conduction path and surface roughness, leading to the variations in TCC.

Magnetic-induced dynamically enhanced in-plane or out-of-plane thermal conductivity of BN/Ag NWs@Ni/epoxy composites

The thermal conductivity of polymer composites could be improved through the orientation of fillers in specific directions. Here, a novel strategy to fabricate BN/Ag nanowires@Ni/epoxy composites (BN/Ag NWs@Ni/EP) to dynamically improve the in-plane or out-of-plane thermal conductivity of the composites in real-time by changing the direction of the magnetic field was investigated. The thermal conduction path was constructed by Ag NWs bridging between BN flakes. Ag NWs@Ni would be oriented in the in-plane or out-of-plane direction by changing the direction of the magnetic field. The out-of-plane or in-plane thermal conductivities of the composites were 0.824 and 0.723 W m−1K−1 at 40 wt% BN/Ag NWs@Ni content, and the corresponding TCEs were 429% and 359% respectively when Ag NWs@Ni was oriented in the out-of-plane or in-plane direction. Meanwhile, BN/Ag NWs@Ni/EP exhibited good mechanical and dielectric properties, which were beneficial for its industrial application in electronic packaging. This strategy provides the possibility for the applications that required the adjustment of the heat conduction direction in real-time.

Embedded Microfluidic Cooling in Aluminum Nitride HTCC Substrate for High-Power Radio Frequency Chip Array

Abstract Radio frequency (RF) electronics are developing toward high power, high integration, and high-power density, resulting in a continuous increase in heat flux. The traditional high-power RF package, which is usually composed of aluminum nitride (AlN) substrate, aluminum silicon housing shell, and aluminum alloy cold plate, exhibits poor heat dissipation ability and high thickness due to excessive interfaces and a long thermal conduction path. In this paper, aimed at improving heat dissipation ability and reducing the thickness of RF electronics, the microchannel was transferred from the cold plate to the AlN high-temperature co-fired ceramic (HTCC) substrate which plays the role of electrical connection, structural support, and liquid cooling cold plate. The embedded AlN microchannel cooler was firstly designed. Then, a prototype of the AlN substrate with 64 simulated chip arrays and microchannels was fabricated and the thermal performance was evaluated using an experimental setup. Finally, the thermal performances of the proposed and traditional cooler were compared using a CFD simulation. The results indicated that the proposed embedded cooling structure could enhance the heat-flux dissipation ability by 61% and reduce the packaging thickness by 40% compared with the traditional cooling structure.

Enhanced thermal properties of HDPE/EG nanocomposites via synergy of multi‐source pulsating flow and phase transition

AbstractA new melt mixing and in‐situ exfoliation method based on the synergy of multi‐source pulsating flow and phase transition (MSPFPT) was reported. The corresponding device was also developed, and the structure and mixing process of the mixer were introduced in detail. High‐density polyethylene (HDPE)/expanded graphite (EG) composites were prepared via this new mixer, and microstructure and thermal properties of the composites were comprehensively investigated. Morphological analyses demonstrate that MSPFPT method promotes the efficient exfoliation and uniform dispersion of EG. The well‐exfoliated EG layers form more thermal conductive paths in the composites prepared by MSPFPT, increasing thermal conductivity from 0.47 of pure HDPE to 1.16 W/(m·K) with 9 wt.% EG. The crystallinity degree of HDPE is increased by 11.1%. The increment of crystallinity reduces phonon scattering, which further confirms that MSPFPT method can significantly improve the thermal performance. The research provides a practical strategy for fabricating high‐performance composites filled with layered fillers.

0D-2D nanohybrids based on binary transitional metal oxide decorated boron nitride enabled epoxy resin efficient flame retardant coupled with enhanced thermal conductivity at ultra-low additions

Epoxy resin (EP) possesses standout traits in adhesion, electrical insulation, as well as mechanical properties, thus it is frequently concerned in the field of electronic packaging. However, EP has shortcomings of poor flame retardancy and thermal conductivity, and it is easy to induce thermal runaway in long-term service. In this work, 0D-2D nanohybrids (BN@CoFeOx) were obtained through a facile coprecipitation-thermal oxidation method, where cobalt-iron metal oxides as decorations were in situ generated on the surface of boron nitride (BN) as the substrate. Then, EP/BN@CoFeOx nanocomposites were prepared by physical blending of BN@CoFeOx and EP, pouring and curing. BN@CoFeOx nanohybrids fulfilled homogeneous dispersion in EP and strong interfacial interactions with the EP matrix. Besides, BN@CoFeOx nanohybrids imparted EP with high flame-retardant efficiency and exceeding smoke suppression properties at low additions of only 2 wt%, reflected in a 44.7%, 42.7%, 54.8%, and 56.2% decrease of the peak heat release rate (pHRR), total heat release rate (THR), peak smoke production rate (pSPR), and total smoke production (TSP) values, respectively. Furthermore, the limiting oxygen index (LOI) value increased from 24.2% of EP to 34.3%, and the vertical combustion test (UL-94) results reached a V0 rating. Meanwhile, the introduction of BN@CoFeOx nanohybrids adjusted for the formation of highly graphitized carbon layers, and boosted the thermal stability of EP. When the addition of BN@CoFeOx nanohybrids was 0.5 wt%, the peak mass loss rate (Rmax) of EP/BN@CoFeOx nanocomposites dropped by 33.6%. In addition, on account of the phonon transfer within and between nanohybrids, combined with the thermal conduction path formed by nanohybrids, BN@CoFeOx accomplished the thermal conductivity enhancement of EP. Hence, the newly designed and prepared EP/BN@CoFeOx nanocomposites provide the possibility to dissipate heat accumulation and promote the flame-retardant performance of electronic products, and consequently reduce the occurrence of thermal runaway.

Recyclable, Self-Healing, and Highly Thermal Conductive Natural Rubber Nanocomposites Enabled by a Dynamic Covalent Network with Carboxylated Boron Nitride Nanosheets

It is of great significance for saving resources and protecting the environment to endow rubber with excellent recycling ability. Recyclable and self-healing ENR/BN-COOH/GO nanocomposites were prepared through dynamic covalent crosslinking between epoxidized natural rubber (ENR) and carboxylated boron nitride (BN-COOH), and graphene oxide (GO) was used as a reinforcing filler. The constructed dynamic β-hydroxyl ester bond between ENR and BN-COOH resulted in the remarkable enhancement of interfacial interaction and effective energy dissipation, which contributed to good mechanical properties of the nanocomposites, increasing by 116 and 79% in comparison with ENR and ENR/GO, respectively. An exchangeable β-hydroxyl ester bond could regulate a network topology structure via a transesterification reaction at the interface, endowing ENR with desirable recycling and self-healing ability. Moreover, the significant improvement of thermal conductivity for ENR/BN-COOH/GO nanocomposites was achieved, reaching 2.853 W/(m·K) at only 6 wt % BN-COOH content, indicating the formation of effective thermal conductive paths via the β-hydroxyl ester bond and hybrid thermal conductive network of BN-COOH/GO. Meanwhile, the thermal conductivity of recycled samples still maintained a high level due to the construction of the stable thermal conductive network. Such a facile strategy exhibits a promising perspective in preparing recyclable and highly thermal conductive rubber nanocomposites for applications in efficient thermal management fields.

Structural Design and Research Progress of Thermally Conductive Polyimide Film - A Review.

Currently, heat accumulation has seriously affected stabilities and life of electronic devices. Polyimide (PI) film with high thermal conductivity coefficient (λ) has long been held up as an ideal solution for heat dissipation. Based on the thermal conduction mechanisms and classical thermal conduction models, this review presents design ideas of PI films with microscopically ordered liquid crystalline structure which are of great significance for breaking the limit of λ enhancement and describes the construction principles of thermal conduction network in high-λ filler strengthened PI films. Furtherly, the effects of filler type, thermal conduction paths and interfacial thermal resistances (ITR) on thermally conductive behavior of PI film are systematically reviewed. Meanwhile, this paper summaries the reported research and provides an outlook on the future development of thermally conductive PI films. Finally, it is expected that this review will give some guidance to the future studies in thermally conductive PI film. This article is protected by copyright. All rights reserved.

Zn_{1-x}Ni_xTe semiconductor nanocrystals in transparent glass for optoelectronic device applications

Doping glass with semiconductors, particularly with nanostructured semiconductors, has attracted attention due to the large optical absorption cross-sections of the latter. Based on this property, Ni^{2+} (5 wt%) doped phosphate glass and Zn_{1-x}Ni_xTe (x = 0.5, 1.0, 5.0 and 10.0 wt% of Ni^{2+}) nanocrystals (NCs) doped phosphate glasses (GCs) were prepared by fusion method and subsequent heat treatment. Influence of Ni^{2+} on structural, thermo-optical and third-order nonlinear optical properties have been analysed through various spectroscopic characterizations. The XRD pattern of the glass (G) exhibits the amorphous nature of the host material while GCs exhibit not only amorphous halo but also the presence of quantum dots (QDs) or nanocrystals (NCs) phases. TEM analysis of the studied GCs samples confirm the presence of quantum dots (QDs) and bulk NCs with an average diameter of approximately 4.2 {pm } 0.3 nm and 13.4 {pm } 0.2 nm, respectively. Several phosphate groups were observed and reported from Raman and FTIR-ATR spectra. The absorption band positions confirmed that Ni^{2+} ions resemble to the octahedral symmetry. The intensity of absorption band around 1352 nm (^3T{_1}(F) rightarrow^3A{_2}(F)) increased with the increase of Ni^{2+} in GCs which is an indicative of the ^{[6]}Ni^{2+} coordination. The emission properties such as emission cross-sections ({sigma }_{emi}) full width at half maxima (FWHM) for the ^1T{_2}(D) rightarrow^3T{_2}(F) (visible) and ^3A{_2}(F) rightarrow^3T{_1}(F) (near-infrared) emission transitions were reported. Among the glass-containing semiconductor nanocrystals (GCs), the emission cross-sections in GC4 sample (x = 10% of Ni^{2+}) are the largest for both the visible (11.88 times 10^{-18} cm^2) and infrared (0.98 times 10^{-20} cm^2) transitions. Thermal diffusivity (D), thermal conductivity (K) and temperature dependent optical path length change (ds/dT) were obtained through time-resolved thermal lens (TL) and thermal relaxation (TR) methods. The D and K parameters do not change significantly with increase of Ni^{2+} ions (0.5–5%) in GCs. Nonlinear-refractive index and nonlinear absorption of the studied samples were also obtained using femtosecond Z-scan technique. The increase of nonlinear absorption coefficient (beta) is observed from GC2 (2.53 {times } 10^{-10} cm/W) to GC4 (7.98 {times } 10^{-10} cm/W). The GC4, sample with 10 wt% of Ni^{2+}, showed the lowest ds/dT (1.22 times 10^{-6} K^{-1}) with good lasing (FOM and emission cross-sections) and nonlinear absorption properties suggesting that it can be a good candidate for visible-red emission light conversion in LED technology.

Construction and the performance of the combination heat transfer mode of Dots-and-Plane based on liquid metal and AlN

High-efficiency thermal conductivity is highly needed for highly-speed developed communication and integrated circuit. Gallium (Ga)-based liquid metal (LM) is a classic of metal with low melting point, and is concerned as a potential thermal interface material (TIM) due to high thermal conductivity (Tc, 16.5 W m−1 K−1). However, the leakage of LM can lead to the serious risk of short circuit and corrosion. This work proposes a strategy where the high-Tc powders of aluminum nitride (AlN) are mixed with LM to construct the heat conduction path combining dots (AlN) and plane (LM) and further to constrain the LM leakage. Specially, a LM-AlN composite paste filled with bimodal size particles displays a high Tc of 68 W m−1 K−1. Based on the simulation result, the bimodal size particles can construct more efficient thermal conductive path combining dots-and-plane, and the high Tc LM is speculated to help build heat transfer pathways among particles through particle-LM-particle. The LM successfully avoided the trouble of leakage during the process of testing, printing, and application. The high thermal conductivity of LM-AlN composite is further demonstrated by a light-emitting diode (LED) heat management test. This research will open a new direction for the development of high-performance TIM.

Lightweight chopped carbon fiber/carbon composites with low thermal conductivity fabricated by vacuum filtration method

Lightweight carbon fiber/carbon composites (CFC) are widely used in solar silicon furnace, semiconductor long crystal furnace and other high-temperature equipment due to its superior low thermal conductivity, low expansion coefficient, high purity, good mechanical properties, and high temperature resistance. In this paper, the lightweight chopped CFC was prepared by the method of liquid phase dispersion of chopped carbon fibers-vacuum filtration-curing molding-high temperature carbonization and graphitization. The thermal conductivity of lightweight chopped CFC with different densities (0.12, 0.16 and 0.18 g/cm3) was studied, and the thermal conductivity of lightweight chopped CFC at high temperature was also studied. The results show that the thermal conductivity (1000 °C) of the chopped CFC gradually increases with the increasing density from 0.179 W/(mK) (0.12 g/cm3) to 0.190 W/(mK) (0.16 g/cm3), 0.282 W/(mK) (0.18 g/cm3), indicating that with the increasing density, the thermal conduction path of the carbon fiber increases, the thermal conductivity of the CFC material increases, and then the thermal insulation performance decreases. In addition, with the increasing temperature, the phonon vibration increases, the thermal conductivity of the CFC material also increases, and then the thermal insulation performance decreases.

HDPE/CNTs/CF shaped PEG-based phase change composite assisted by supercritical CO2

The inexhaustible solar energy is a non-negligible alternative to alleviate energy crisis, yet its intermittency and low light-thermal conversion efficiency have become the major challenges for material engineers. In this study, a green and facile supercritical CO2 foaming-assisted vacuum impregnation technique was applied to fabricate the shape-stability HDPE/CNTs/CF/PEG phase change composite (PCC). This advanced manufacturing technology concentrates the CNT and CF in HDPE porous foams, which increases the effective concentration of fillers, thereby enhancing the probability of fillers overlapping each other to form the electrically conductive and thermal conductive paths. Benefiting from this, the PCC is blessed with satisfactory thermal conductivity (0.653 W m−1 K−1), superior light-thermal conversion efficiency (98.1%), suitable phase change enthalpy (142.8 J g−1) and electromagnetic shielding property (19.01 dB). Accordingly, this favorable and facile preparation technology attach promising applications to PCCs in the fields of solar energy utilization, electromagnetic shielding, and thermal management.

Enhancing thermal conductivity of epoxy composites via f‐BN@f‐MgO hybrid fillers assisted by hot pressing

AbstractHigh thermal conductive polymeric composites are extremely desired for the thermal management of electronic devices due to the rapid development of the modern microelectronic industry. Herein, the functionalized boron nitride (BN) and magnesium oxide (MgO) hybrid fillers (f‐BN@f‐MgO) were synthesized and used to prepare the enhanced thermal conductive epoxy (EP) composites through the hot‐pressing method. The results demonstrated that the covalent binding of BN and MgO in the hybrid fillers reduced the interface thermal resistance effectively between fillers and matrix and the hot‐pressing induced force facilitated the construction of the continuous thermal conduction paths. Consequently, the as‐prepared epoxy composite at 40 wt% hybrid fillers loading had high thermal conductivity (TC) (1.97 W/[m·K]), outstanding insulating performance (6.9 × 1015 Ω cm) and excellent thermal stability. Furthermore, a probable thermal conduction mechanism was proposed to illustrate the high TC of the epoxy composite. Therefore, this study provides a new approach to preparing epoxy composites with outstanding performances.

Anisotropically conductive phase change composites enabled by aligned continuous carbon fibers for full-spectrum solar thermal energy harvesting

Solar thermal energy harvesting with phase change materials (PCMs) can overcome the intermittent nature of solar energy through thermal energy storage to provide uninterruptible heat supply. However, the PCMs' intrinsically low thermal conductivities and weak solar absorptances pose considerable challenges to achieving high photothermal efficiency, and most PCMs also suffer from leakage and poor stability. Herein, we propose a simple and scalable approach to develop anisotropically conductive phase change composites (PCCs) by fabricating and embedding aligned continuous carbon fibers (CFs) in paraffin wax (PW)/olefin block copolymer (OBC) blends. The aligned CFs provide continuous and directional thermal conduction paths within the PCCs, enabling a high lengthwise thermal conductivity of 5.63 W·K−1·m−1 and a low transverse thermal conductivity of 0.77 W·K−1·m−1 with a rather high anisotropic degree of 7.31. The excellent anisotropic thermal conductivity can enhance the lengthwise heat transfer from the PCC surface to the deep inside and reduce the transverse heat loss from PCC to the surroundings. Furthermore, to enhance the solar absorption, carbon black is coated on the PCC surface to boost the full-spectrum solar absorptance up to 0.988. Because of the synergetic effects of the excellent anisotropic thermal conductivity and high full-spectrum solar absorptance, the PCC can achieve high photothermal efficiencies of 79.17 %-98.31 % under 1 sun-3 suns. Moreover, the PCC also demonstrates excellent thermal, cyclic and shape stability. This work offers a promising strategy for fabricating anisotropically conductive PCCs for efficient solar thermal energy harvesting.

Tunable Head-Conducting Microwave-Absorbing Multifunctional Composites with Excellent Microwave Absorption, Thermal Conductivity and Mechanical Properties

Developing composite materials with both thermal conductivity and microwave absorption is an effective strategy to solve the problems of heat dissipation burden and microwave radiation interference caused by the development of miniaturization and high performance of portable electronic equipment. However, these properties are not easy to simultaneously implement due to the limitation of single type fillers with a single particle size, inspiring the possibility of realizing multifunctional composites with the introduction of composite fillers. In this work, using alumina (Al2O3) and zinc oxide (ZnO) as head-conducting fillers, carbonyl iron (Fe(CO)5) as microwave-absorbing fillers, silicone rubber (SR) composites (Al2O3/ZnO/Fe(CO)5/SR) with enhanced microwave absorption, high thermal conductivity and good mechanical properties were successfully mass prepared. It was found that the composites can achieve a thermal conductivity of 3.61 W·m−1·K−1, an effective microwave absorption bandwidth of 10.86–15.47 GHz. Especially, there is an effective microwave absorption efficiency of 99% at 12.46–14.27 GHz, which can realize the integration of electromagnetic shielding and heat dissipation. The compact microstructure, formed by the overlapping of large particle size fillers and the filling of their gaps by small particle size fillers, is helpful to enhance the thermal conduction path and weaken the microwave reflection. The heat-conducting microwave-absorbing Al2O3/ZnO/Fe(CO)5/SR composites also have the advantages of thermal stability, lightness and flexibility, providing a certain experimental basis for the research and development of high-performance and diversified composites.

Enhanced electrically and thermally conductive free-standing graphene films with two-dimensional copper sheets as the catalyst and bridge.

Two-dimensional copper sheets were introduced as the catalyst and bridge to enhance the electrical and thermal conductivity of graphene films prepared from graphene oxide nanosheets via a thermal reduction method. The effects of adding different amounts of copper sheets in the composite films were investigated, and the results show that the electrical and thermal conductivity of the graphene films could be increased by 3 times and 64.9%, respectively. The two-dimensional copper sheets not only play an important role as a catalyst toward improving the graphitization degree of reduced graphene oxide, but also act as a bridge and promote the interconnection of the electrical and thermal conduction paths in the composite films due to the good electrical and thermal conductivity of copper. Moreover, the heat dissipation experiment shows that this enhanced graphene composite film has potential applications in the heat management of electronics.

Orientated growth the 3D diamond/graphene hybrid arrays and the application in thermal interface materials

Diamond and graphene are considered to be one of the most promising thermal interface materials (TIMs) for electronic devices benefited from their highest thermal conductivity in the natural world. However, orientated fabrication of high thermal conductivity diamond and graphene hybrid arrays with three dimensions (3 D) thermal conductive networks are still problematic. Here, we used a unique one-step microwave plasma chemical vapor deposition, n-butylamine, as the liquid source to prepare a novel high thermal conductivity 3 D vertical diamond/graphene (VDG) hybrid arrays films. The orientated 3 D thermal conduction path of the VDG is regulated by the growth temperature, and the through-plane thermal conductivity value of the VDG700 films up to 97 W m−1 K−1. In the actual TIM performance measurement, the system cooling efficiency with our VDG as TIM is higher than the state-of-the-art commercial TIM, demonstrating the superior ability to solve the inter-facial heat transfer issues in electronic systems.

MgAl Layered Double Oxide/Reduced Graphene Oxide Composites with Reduced Interfacial Thermal Resistance for Thermal Conductivity and Electrical Insulation Applications

Research and development of polymer composites with high thermal conductivity and excellent electrical insulation are one of the research hotspots in thermal management. Although the thermal conductivity issue has been improved effectively with many methods, it remains challenging due to the interface thermal resistance issues and how to hold the electrical insulation performance at high thermal conductivity. Herein, MgAl layered double oxide/reduced graphene oxide (MgAl-LDO/rGO-s) with a hierarchical structure was innovatively used in the CNF thermal conductivity field. The lamellar structure and strong interfacial interactions between MgAl-LDO and rGO construct the continuous thermal conduction path for phonons transport, and the interface thermal resistance is effectively reduced. Meanwhile, the insulated MgAl-LDO forms a hierarchical structure on the surface of rGO by its positive charge characteristics and keeps excellent electrical insulation properties. Therefore, the CNF/MgAl-LDO/rGO-s composite films exhibit high in-plane thermal conductivity (8.7 W·m–1·K–1), electrical insulation (ρv > 1013 Ω·m), and excellent thermal stability. This work provides an interface engineering strategy for heat conduction and electrical insulation and broadens the upper limit application of thermally conductive polymer composites (TCPC) in thermal management.