Thermal Interface Research Articles

Self-assembled nest-like BN skeletons enable polymer composites with high thermal management capacity

The lagging development of thermally conductive but electrically insulating materials has become a bottleneck problem for the next generation of advanced high-power density electronic devices. Although second-phase reinforced composites are promising materials for addressing thermal management issues, the inherent mechanism of severe phonon scattering at the interphase results in actual thermal conductivity enhancement efficiency far below expectations. Here, we report a high-performance polymer composite with a nest-like interconnected boron nitride skeleton. This nest-like interconnected BN skeleton without mechanical contact can provide high-efficiency and long-distance phonon transport channel, realizing high thermal conductivity of 1.827 W m-1 K-1 in polymer composite with ultra-low content (4.7 vol%). Meanwhile, the EP/ nest-like BS composites possess ideal electrical properties and dimensional stability. In the actual heat dissipation process of LED chips, the optimal composite material as the thermal interface material can display a temperature drop of more than 34.8% compared to neat epoxy, which proves the broad application prospects of this strategy in advanced electronic devices.

Replacing the Gallium Oxide Shell with Conductive Ag: Toward a Printable and Recyclable Composite for Highly Stretchable Electronics, Electromagnetic Shielding, and Thermal Interfaces.

Liquid metal (LM)-based composites hold promise for soft electronics due to their high conductivity and fluidic nature. However, the presence of α-Ga2O3 and GaOOH layers around LM droplets impairs conductivity and performance. We tackle this issue by replacing the oxide layer with conductive silver (Ag) using an ultrasonic-assisted galvanic replacement reaction. The Ag-coated nanoparticles form aggregated, porous microparticles that are mixed with styrene-isoprene-styrene (SIS) polymers, resulting in a digitally printable composite with superior electrical conductivity and electromechanical properties compared to conventional fillers. Adding more LM enhances these properties further. The composite achieves EMI shielding effectiveness (SE) exceeding 75 dB in the X-band frequency range, even at 200% strain, meeting stringent military and medical standards. It is applicable in wireless communications and Bluetooth signal blocking and as a thermal interface material (TIM). Additionally, we highlight its recyclability using a biodegradable solvent, underscoring its eco-friendly potential. This composite represents a significant advancement in stretchable electronics and EMI shielding, with implications for wearable and bioelectronic applications.

Balancing Interfacial Toughness and Intrinsic Dissipation for High Adhesion and Thermal Conductivity of Polymer-Based Thermal Interface Materials.

In recent years, adhesive thermal interface materials have attracted much attention because of their reliable adhesion properties on most substrates, preventing moisture, vibration impact, or chemical corrosion damage to components and equipment, as well as solving the heat dissipation problem. However, thermal interface materials have a huge contradiction between strong adhesion and high thermal conductivity. Here, we report a polymer-based thermal interface material consisting of polydimethylsiloxane/spherical aluminum fillers, which possesses both adhesion properties (adhesion strength of 3.59 MPa and adhesion toughness of 1673 J m-2 and enhanced thermal conductivity of 3.90 W m-1 K-1). These excellent properties are attributed to the modified chain structure by introducing acrylate accelerators into the polydimethylsiloxane network, thereby striking a balance between interfacial toughness and intrinsic dissipation. The addition of thermally conductive aluminum fillers not only increases the thermal conductivity but also improves the bulk energy dissipation of the thermal interface material. This work provides a novel strategy for designing a novel thermal interface material, leading to new ideas in long-term applications in high-power electronics.

A flexible thermal interface composite of copper-coated carbon felts with 3d architecture in silicon rubber

Thermal interface materials (TIM) are key thermal management components to enhance the performance of electronic products, and how to improve thermal conductivity is a key issue to consider. As a high thermal conductivity material, it is difficult for copper to have both high thermal conductivity and high elasticity when filled into the polymer. In this paper, by growing copper nanoparticles on the surface of carbon felt (Cfelt), a three-dimensional interoperable thermally conductive copper network is formed with carbon fibers as the support, which makes the material both better thermally conductive and elastic at the same time. The vertical thermal conductivity of the prepared Cu-Cfelt/silicon rubber composite material reached 7.3230 W/mK. It is 23 times higher than pure silicon rubber(0.3130 W/mK), 18 times higher than Cu/silicon rubber composite (0.4120 W/mK) and 12 times higher than CFelt/silicon rubber composite (0.6200 W/mK), and successfully improves the thermal conductivity of the interface. The three-dimensional Cu network structure of the prepared Cu-CFelt/silicon rubber composite maximized the thermal conductivity of Cu, and the composite also showed excellent mechanical properties, indicating that the composite has broad application prospects in thermal management and other aspects.

A novel steady-state method for measuring thermal conductivity of thermal interface materials with miniaturized thermal test chips

Thermal interface materials (TIMs) are widely used in electronic device packaging, and accurate characterization of their thermal properties is essential. However, existing TIM test platforms suffer from large size and inconsistency between copper-based test platforms and packaged silicon materials. To address these issues, this study proposes a method based on a miniaturized testing platform constructed using silicon-based thermal test chips (TTC). The thermal conductivity of several specimens was measured using steady-state heat source thermal transmission. The total thermal resistance, thermal contact resistance and thermal conductivity of several TIMs were evaluated through theoretical analysis and experimental verification. The thermal conductivity of several TIMs was tested using the proposed Back-to-Face and Back-to-Back TTC modules. The results demonstrate that this method exhibits high accuracy and can be used to characterize a wide range of TIMs.

Improving the thermal, mechanical, and insulating characteristics of thermal interface materials with liquid metal-based diphase structure

Improving the thermal, mechanical, and insulating characteristics of thermal interface materials with liquid metal-based diphase structure

Thermally conductive and electrically insulated DGEBA-epoxy nano-composite fabricated by integrating GO/h-BN and rGO/h-BN hybrid for thermal management applications: a comparative analysis

Abstract Thermal interface materials (TIMs) are prerequisite components of micro- and nano-electronics, as well as advanced semiconductor applications. A bisphenol-A epoxy-based thermal adhesive amalgamated graphene oxide (GO), reduced graphene oxide (rGO), and modified hexagonal boron nitride (h-BN/mh-BN) are fabricated. The advantages of adhesive TIMs compared to other TIMs encompass lower cost, process savings, reduced component weight, and prevention of vibration loosening the high-end electronics. Additionally, some parts are not suitable for soldering, as they may lack “legs” that go through holes in the PCBs, and adhesive TIMs help prevent short circuits. The thermal conductivity (TC) is measured at 1.653 ± 0.057 W/mK when incorporating 44.5 wt% mh-BN hybrid rGO into the epoxy matrix. However, substituting rGO with GO reduced the TC to 0.81 ± 0.0289 W/mK due to the lower phonon transfer of GO compared to rGO. The binding strength, in terms of lap shear, of the utmost TC composite adhesive was within the range of 6.26 ± 0.48 MPa, which is acceptable for effective end applications. The thermal stability of both optimized composites (mh-BN/rGO and mh-BN/GO) has demonstrated better results beyond 280 °C. The highest TC epoxy nanocomposite, termed mh-BN/rGO4/epoxy, also revealed electrical insulation properties.

Bio-Inspired Thermal Conductive Fibers by Boron Nitride Nanosheet/Boron Nitride Hybrid.

With the innovation of modern electronics, heat dissipation in the devices faces several problems. In our work, boron nitride (BN) with good thermal conductivity (TC) was successfully fabricated by constructing the BN along the axial direction and the surface-grafted BN hybrid composite fibers via the wet-spinning and hot-pressing method. The unique inter-outer and inter-interconnected hybrid structure of composite fibers exhibited 176.47% thermal conductivity enhancement (TCE), which exhibits good TC, mechanical resistance, and chemical resistance. In addition, depending on the special structure of the composite fibers, it provides a new strategy for fabricating thermal interface materials in the electronic device.

Thermal Interface Materials with High Adhesion and Enhanced Thermal Conductivity via Optimization of Polydimethylsiloxane Networks and Aluminum Fillers

Thermal Interface Materials with High Adhesion and Enhanced Thermal Conductivity via Optimization of Polydimethylsiloxane Networks and Aluminum Fillers

Ultra-efficient Heat Transport across a "2.5D" All-carbon sp2/sp3 Hybrid Interface.

Single- and few-layer graphene-based thermal interface materials (TIMs) with extraordinary high-temperature resistance and ultra-high thermal conductivity are very essential to develop the next-generation integrated circuits. However, the function of the as-prepared graphene-based TIMs would undergo severe degradation when being transferred to chips, as the interface between the TIMs and chips possesses a very small interfacial thermal conductance. Here, a "2.5D" all-carbon interface containing rich covalent bonding, namely a sp2/sp3 hybrid interfaces is designed and realized by a plasma-assisted chemical vapor deposition with a function of ultra-rapid quenching. The interfacial thermal conductance of the 2.5D interface is excitingly very high, up to 110-117 MWm-2K-1 at graphene thickness of 12-25 nm, which is even more than 30% higher than various metal/diamond contacts, and orders of magnitude higher than the existing all-carbon contacts. Atomic-level simulation confirm the key role of the efficient heat conduction via covalent C-C bonds, and reveal that the covalent-based heat transport could contribute 85% to the total interfacial conduction at a hybridization degree of 22 at%. This study provides an efficient strategy to design and construct 2.5D all-carbon interfaces, which can be used to develop high performance all-carbon devices and circuits.

Ultra‐efficient Heat Transport across a “2.5D” All‐carbon sp2/sp3 Hybrid Interface

Single‐ and few‐layer graphene‐based thermal interface materials (TIMs) with extraordinary high‐temperature resistance and ultra‐high thermal conductivity are very essential to develop the next‐generation integrated circuits. However, the function of the as‐prepared graphene‐based TIMs would undergo severe degradation when being transferred to chips, as the interface between the TIMs and chips possesses a very small interfacial thermal conductance. Here, a “2.5D” all‐carbon interface containing rich covalent bonding, namely a sp2/sp3 hybrid interfaces is designed and realized by a plasma‐assisted chemical vapor deposition with a function of ultra‐rapid quenching. The interfacial thermal conductance of the 2.5D interface is excitingly very high, up to 110‐117 MWm‐2K‐1 at graphene thickness of 12‐25 nm, which is even more than 30% higher than various metal/diamond contacts, and orders of magnitude higher than the existing all‐carbon contacts. Atomic‐level simulation confirm the key role of the efficient heat conduction via covalent C‐C bonds, and reveal that the covalent‐based heat transport could contribute 85% to the total interfacial conduction at a hybridization degree of 22 at%. This study provides an efficient strategy to design and construct 2.5D all‐carbon interfaces, which can be used to develop high performance all‐carbon devices and circuits.

Low magnetic field alignment of carbon fibers in a polymer matrix for high-performance thermal interface materials

Carbon-based materials like carbon nanotubes, graphene nanoplatelets, graphite, and carbon fibers (CF) are highly promising fillers for enhancing the thermal conductivity of thermal interface materials (TIMs) due to their high thermal conductivity and low thermal expansion. Aligning these fillers can further improve thermal conductivity, but current alignment methods using high magnetic fields are impractical for industrial use. In this study, we investigated the enhancement of the thermal conductivity of CF–polymer composites by aligning CF fillers with a low magnetic field. We observed up to 17 times enhancement of the thermal conductivity (from 3.1 to 52.8 W/mK) in a CF–graphene–polymer composite film by vertically aligning the CF fillers with a magnetic field of 0.75 T. The analysis of the structural properties of the films using X-ray diffraction and field-emission scanning electron microscopy imaging confirmed that the crystalline c-axis of the graphite plates in the CF was oriented perpendicular to the magnetic field direction. The large anisotropy in the diamagnetic susceptibility of the laminated graphene structure of the CF flakes is at the origin of the filler alignment. Furthermore, the thermal conductivity of the composites showed a strong correlation with the degree of filler alignment, which was dependent on the CF–graphene hybridization and the type of polymer matrix. This study provides a scalable and cost-effective method for enhancing the physical properties of carbon composites by controlling their microarchitecture using a low magnetic field.

Enhanced thermal conductivity of UHMWPE by coating boron nitride and polyurethane composites

The development of textile wearable electronics has increased demands and requirements for thermal management materials due to integrated and miniaturized soft equipment. In this work, the surface of ultrahigh molecular weight polyethylene (UHMWPE) fibers was first decorated by polydopamine (PDA) to improve the surface activity and construct a steady interface layer. Then the boron nitride/polyurethane coating surface modified UHMWPE composite yarns with good thermal conductivity were produced using a coaxial wet forming process. The thermally conductive composite yarns demonstrated great mechanical properties (5.09 % strain, 0.79 N/tex strength) and thermal conductivity (0.54 ± 0.02 W·mK−1) with the BN/PU weight ratio of 1. Furthermore, the resistance to failure cycles was taken place, and the composite yarns kept good thermal conductivity after multiple cycles twisting, bending, washing, cooling and heating cycles. By the coaxial wet fabrication, the thermally conductive composite yarns were constructed, offering a viable and trustworthy method for creating polymer-based thermal interface materials with high thermal conductivity.

3D Network of Liquid Metal-Embedded Graphene via Surface Coating for Flexible Thermal Management.

The rapid growth of flexible electronics has led to significant demand for relevant accessories, particularly highly efficient flexible heat dissipators. The fluidity of liquid metal (LM) makes it a candidate for realizing flexible thermal interface materials (TIMs). However, it is still challenging to combine LM with a conductive thermal network to achieve the synchronous improvement of thermal conductivity and flexibility. In this work, highly conductive flexible LM@GN/ANF films are made by coating LM nano-droplets with graphene nanosheets (GN) via sonication, and then they are combined with aramid nanofibers (ANF). The LM@GN/ANF film is found to have a thermal conductivity of 5.67Wm-1K-1 and a 24.5% reduction in Young's modulus, making it suitable for various flexible electronic applications such as wearable devices and biosensors.

Phase change thermal interface film with bicontinuous and textured filler network for efficient wearable heat dissipation

Wearable thermal management needs to simultaneously meet thermal conductivity, heat storage capacity, stability, flexibility, and economy, but these characteristics constrain each other in the development of phase change thermal interface materials (PhC-TIM). Therefore, relying on the economic bicontinuous structure for fillers’ orientation, a new type of bicontinuous phase change thermal interface material (BPTIM) was designed, which includes thermal storage phase composed of paraffin (PCMs) and flexible molecule styrene–butadiene–styrene (SBS), and thermal conductivity phase composed of adhesive polyurethane (PU) and thermal conductive medium boron nitride (h-BN). In the experiment, shear force generated by stirring and optimized two-phase volume ratio resulted in the stretching and compressing of the thermal conductive phase, promoting the orientation of h-BN and ultimately forming a textured thermal-conductive network in a high PCMs content bicontinuous structure. Moreover, the introduction of SBS had brought bending resistance and thermal stability. These characteristics enabled BPTIMs to significantly reduce the surface temperature of the wearable device by 23 °C. Overall, this design provides a certain reference for the widespread application of PhC-TIM in thermal management of wearable electronic products.

Multifunctional Thermal Interface Composites with Enhanced Thermal Conductivity, EMI Shielding Capabilities, and Mechanical Performance

Multifunctional Thermal Interface Composites with Enhanced Thermal Conductivity, EMI Shielding Capabilities, and Mechanical Performance

Highly thermally conductive and anti-corrosive silicone grease enabled using unique hexagonal boron nitride nanosheet/alumina microsphere-based hierarchical structure for heat dissipation in a humid environment

Electronic devices operating in the marine environment often face severe corrosion. In addition, highly integrated and powerful devices generate a notable amount of heat, which may lead to a deterioration in performance and reliability. Therefore, it is essential to develop thermal interface materials (TIMs) with high thermal conductivity and outstanding corrosion resistance for efficient and stable heat dissipation. Herein, a novel hierarchical three-dimensional structure comprising hexagonal boron nitride sheet wrapped alumina microsphere/hexagonal boron nitride flakes (Al2O3@BNNS-BNFs) has been fabricated, which can simultaneously improve the thermal conductivity and corrosion resistance of silicone grease (SG). The dispersibility of BNFs in SG is enhanced by the uniform distribution of Al2O3@BNNSs, while the BNNSs attached to the surface of Al2O3 microspheres improves the compatibility of BNFs and Al2O3 microspheres, thereby effectively enhancing the thermal conductivity of SGs. The thermal conductivity of the Al2O3@BNNS-BNFs/SG can reach up to 1.98 W/(m·K) when the content of Al2O3@BNNS-BNFs is 20 wt%, which is ∼13 times that of ordinary SG. Meanwhile, the Al2O3@BNNS-BNFs/SGs also demonstrate excellent electrical insulation (1.50 × 1013 Ω cm) and corrosion resistance compared to some commercial products. Furthermore, subsequent tests indicate that the Al2O3@BNNS-BNFs/SGs can effectively dissipate heat for electronic devices in various humid environments. These unique properties make the Al2O3@BNNS-BNFs/SGs promising as multifunctional TIMs for thermal management in complex environments, especially in humid or corrosive conditions.

High-performance thermal interface materials enabled by vertical alignment of lightweight and soft graphene foams

High-performance thermal interface materials enabled by vertical alignment of lightweight and soft graphene foams

Mechanochemistry-mediated colloidal liquid metals for electronic device cooling at kilowatt levels.

Electronic systems and devices operating at significant power levels demand sophisticated solutions for heat dissipation. Although materials with high thermal conductivity hold promise for exceptional thermal transport across nano- and microscale interfaces under ideal conditions, their performance often falls short by several orders of magnitude in the complex thermal interfaces typical of real-world applications. This study introduces mechanochemistry-mediated colloidal liquid metals composed of Galinstan and aluminium nitride to bridge the practice-theory disparity. These colloids demonstrate thermal resistances of between 0.42 and 0.86 mm2 K W-1 within actual thermal interfaces, outperforming leading thermal conductors by over an order of magnitude. This superior performance is attributed to the gradient heterointerface with efficient thermal transport across liquid-solid interfaces and the notable colloidal thixotropy. In practical devices, experimental results demonstrate their capacity to extract 2,760 W of heat from a 16 cm2 thermal source when coupled with microchannel cooling, and can facilitate a 65% reduction in pump electricity consumption. This advancement in thermal interface technology offers a promising solution for efficient and sustainable cooling of devices operating at kilowatt levels.

Thermal interface materials: From fundamental research to applications

AbstractThe miniaturization, integration, and high data throughput of electronic chips present challenging demands on thermal management, especially concerning heat dissipation at interfaces, which is a fundamental scientific question as well as an engineering problem—a heat death problem called in semiconductor industry. A comprehensive examination of interfacial thermal resistance has been given from physics perspective in 2022 in Review of Modern Physics. Here, we provide a detailed overview from a materials perspective, focusing on the optimization of structure and compositions of thermal interface materials (TIMs) and the interact/contact with heat source and heat sink. First, we discuss the impact of thermal conductivity, bond line thickness, and contact resistance on the thermal resistance of TIMs. Second, it is pointed out that there are two major routes to improve heat transfer through the interface. One is to reduce the TIM's thermal resistance (RTIM) of the TIMs through strategies like incorporating thermal conductive fillers, enhancing interfacial structure and treatment techniques. The other is to reduce the contact thermal resistance (Rc) by improving effective interface contact, strengthening bonding, and utilizing mass gradient TIMs to alleviate vibrational mismatch between TIM and heat source/sink. Finally, such challenges as the fundamental theories, potential developments in sustainable TIMs, and the application of AI in TIMs design are also explored.