Advanced Thermal Interface Materials Research Articles

Unlocking the Trade-off Between Intrinsic and Interfacial Thermal Transport of Boron Nitride Nanosheets by Surface Functionalization for Advanced Thermal Interface Materials.

The increasing computing power of AI presents a major challenge for high-power chip solution and heat dissipation. Boron nitride nanosheet-based thermal interface materials (BNNS-based TIMs) exhibit excellent electrical insulation property, ensuring the secure and stable operation of chips. However, the efficiency of micro/nano interfacial thermal transport is limited, impeding further enhancements in the thermal conductivity (TC) of BNNS-based TIMs. Here, a strategy of surface functionalization is reported to unlock the trade-off between the intrinsic and interfacial thermal transport of BNNS within TIMs. These results suggest that the surface functionalization maintains the intrinsic high TC of BNNS while significantly increasing binding energy between micro/nano interfaces in BNNS-based TIMs, effectively reducing interfacial thermal resistance of BNNS joint interfaces and interfaces between BNNSs and the matrix by 50% and 26.1%, respectively. The BNNS-based TIMs exhibit excellent TC (≈21-25W/(m·K)) and ultralow Young's modulus, which can promote the development of flexible high-performance chip cooling technology in the AI industry.

Experimental study of photovoltaic-thermoelectric systems using thermal interface materials and natural cooling

This study investigates a novel approach to enhancing photovoltaic-thermoelectric generator systems by utilizing advanced thermal interface materials in real-world conditions. The research compares two experimental systems under natural air cooling employing different thermal interface materials: one features a pyrolytic graphite sheet, while the other uses conventional thermal grease, alongside a photovoltaic-only system for reference. An Arduino-based data logger accurately monitored key environmental and operational parameters. At peak solar irradiation, the system with the pyrolytic graphite sheet achieved a surface photovoltaic temperature of 39.01 °C, generating 4.90 W and an overall efficiency of 17.95 %. In comparison, the system with thermal grease had a surface photovoltaic temperature of 48.88 °C, generating 4.67 W with an efficiency of 16.87 %, while the photovoltaic-only system reached a surface photovoltaic temperature of 55.37 °C, producing 4.54 W and an efficiency of 16.42 %. The experimental data’s accuracy and reliability were validated against simulations from previous work, revealing error margins between 1.20 % and 3.03 %. These findings underscore the potential of pyrolytic graphite sheets as effective thermal interface materials to significantly enhance the efficiency and power output of photovoltaic-thermoelectric generator systems, offering valuable insights for optimizing renewable energy technologies.

A Review of Advanced Thermal Interface Materials with Oriented Structures for Electronic Devices

In high-power electronic devices, the rapid accumulation of heat presents significant thermal management challenges that necessitate the development of advanced thermal interface materials (TIMs) to ensure the performance and reliability of electronic devices. TIMs are employed to facilitate an effective and stable heat dissipation pathway between heat-generating components and heat sinks. In recent years, anisotropic one-dimensional and two-dimensional materials, including carbon fibers, graphene, and boron nitride, have been introduced as fillers in polymer-based TIMs due to their high thermal conductivity in specific directions. The orientation of the fillers in the polymer matrix has become an important issue in the development of a new generation of high-performance TIMs. To provide a systematic understanding of this field, this paper mainly discusses recent advances in advanced oriented TIMs with high thermal conductivity (>10 W/(m·K)). For each filler, its preparation strategies and enhancement mechanisms are analyzed separately, with a focus on the construction of oriented structures. Notably, there are few reviews related to carbon fiber TIMs, and this paper details recent research results in this field. Finally, the challenges, prospects, and future development directions of advanced TIMs are summarized in the hope of stimulating future research efforts.

Numerical study on the polydispersive effect of filler size distribution on the properties of thermal interface materials

Abstract Advanced thermal interface materials (TIMs) are indispensable for work reliability and lifespan assurance of high-power density electronic systems by facilitating timely and effective heat dissipation. A random algorithm consisting of diluting, dropping, and stirring processes is first proposed to simulate microstructures of TIMs with continuous particle size distribution, with an accessible maximum volume fraction of 55 vol%. Then the size polydispersity impact on the thermal performance and the fluidity of TIMs is numerically investigated. Simulation results reveal that as the particle size polydispersity increases, the thermal conductivity of TIMs improves, along with the improved fluidity. Therefore, it is necessary to consider the polydispersive impact of filler size distribution in actual production and optimize the material preparation process based on the actual distribution of particles. This work provides a deeper understanding of the influence of particle polydispersity on the co-optimization of the desired attributes of TIMs.

Diamond-Reinforced Al(H2PO4)3@Epoxy Hybrid Thermal Adhesive With Ultra-High Thermal Conductivity and Bonding Strength.

The miniaturization, integration, and increased power of electronic devices have exacerbated serious heat dissipation issues. Thermally conductive adhesives, which effectively transfer heat and firmly bond components, are critical for addressing these challenges. This paper innovatively proposed a composite comprising inorganic phosphate/alumina as a matrix and diamond as filler. The composite achieved an isotropic thermal conductivity (TC) of up to 18.96Wm-1K-1, significantly surpassing existing reports while maintaining electrical insulation. First-principles calculations and experimental tests confirmed that the high TC of phosphate and excellent interface contact ensured efficient heat transfer. To optimize bonding performance, a modified-diamond/Al(H2PO4)3@epoxy hybrid composite is subsequently developed using an organic modification method. The unique hybrid structure, combining inorganic thermal pathways and an organic adhesive network, enabled the hybrid composite to simultaneously possess a high TC (3.23Wm-1K-1) and strong adhesion (14.35MPa). Compared to previous reports, the comprehensive performance of this hybrid thermally conductive adhesive is exceptionally remarkable. The superior heat dissipation capability of the hybrid thermal adhesive is demonstrated in chip cooling scenarios. This organic/inorganic hybrid approach offered a new direction for obtaining advanced thermal interface materials, demonstrating significant application potential in chip soldering, packaging, and heat dissipation.

Enhancement of Thermal Management Performance of Copper Foil Using Additive-Free Graphene Coating.

Advanced thermal interface materials with high thermal conductivity are crucial for addressing the heat dissipation issue in high-power, highly integrated electronic devices. One great potential way in this field is to take advantage of cooling copper foil (Cu) materials based on graphene (G). However, the current manufacturing of these cooling copper foil materials is accompanied by high cost, process complexity, and environmental problems, which limit their development and application. In this work, a simple, low-cost, environmentally friendly graphene-copper foil composite film (rGO/G-Cu) with high thermal conductivity was successfully prepared using graphene oxide directly as a dispersant and binder of graphene coating. The microstructure characterization, thermal conductivity and thermal management performance tests were carried out on the composite films. The results demonstrate that compared to pure copper foil (342.47 W·m-1·K-1) and 10% PVA/G-Cu (367.98 W·m-1·K-1) with polyvinyl alcohol as a binder, 10% rGO/G-Cu exhibits better thermal conductivity (414.56 W·m-1·K-1). The introduction of two-dimensional graphene oxide effectively enhances the adhesion between the coating and the copper foil while greatly improving its thermal conductivity. Furthermore, experimental results indicate that rGO/G-Cu exhibits excellent heat transfer performance and flexibility. This work is highly relevant to the development of economical and environmentally friendly materials with high thermal conductivity to meet the increasing demand for heat dissipation.

Highly thermally conductive and soft thermal interface materials based on vertically oriented boron nitride film

Thermal interface materials (TIMs) with high through-plane thermal conductivity (TC), softness, and electrical insulation are highly desired for modern electronics. However, it is challenging to simultaneously achieve these properties. Boron nitride (BN)-based polymer composites are promising candidates for advanced TIMs owing to the high TC and great electrical insulation of BN. However, previous works perform either low TC (< 8 W m−1 K−1) or high stiffness. The ultimate properties of BN-based TIMs remain largely unclear and unrealized. Here, we fabricate BN film-filled silicone rubber composites by a facile stacking-cutting method, which maintains the high degree of orientation the BN film, so that a record-high though-plane TC of 19.1 W m−1 K−1 and a low compressive modulus of 5.42 MPa are achieved. The low BN content (37 vol%) ensures the softness and resilience of the as-prepared TIMs. This work presents a highly efficient strategy to enhance the performance of BN based TIMs, promoting their large-scale manufacturing and practical applications.

Advanced Thermal Interface Materials: Assembly and Integration for System in Package

Power dissipation is perhaps the greatest challenge facing modern electron devices. It has limited the performance of Si integrated circuits for nearly two decades, and is also limiting the performance of (high-power) GaN discrete devices. As such, many information technologies (ITs) have an urgent need for power dissipation solutions at the hardware level. The most feasible solution is via the device packaging, since self-heating of the device is deeply rooted in fundamental aspects of electron transport in imperfect semiconductors at normal temperatures. This packaging solution often occurs at the die attachment, whereby a thermal interface material (TIM) couples the device to the board. The interface/bulk thermal conductivity of this TIM determines the temperature rise of the device at a given operating power. Today, most TIMs rely on the thermal conductivity of metals, and are rapidly becoming a bottleneck for power dissipation in advanced ITs. This talk will discuss the limitations of metallic TIMs, and integration/characterization challenges for new materials that may extend the performance scaling of high-power devices.

Aligning graphene nanoplates coplanar in polyvinyl alcohol by using a rotating magnetic field to fabricate thermal interface materials with high through-plane thermal conductivity

With the continuous advancement of electronic devices, there is an urgent need for advanced thermal interface materials (TIMs) to prevent high-power density electronics from overheating. The orderly arrangement of thermally conductive fillers in TIMs plays a crucial role in enhancing thermal conduction along preferred directions. However, it is challenging to control the orientation of the fillers, especially for two-dimensional fillers. In this study, graphene nanoplates (GNPs) were co-planarly arranged in polyvinyl alcohol (PVA) using a rotating magnetic field, which significantly increased the thermal conductivity of the composites. The coplanar vertically aligned GNPs/PVA (CVGNPs/PVA) exhibited a through-plane thermal conductivity of 11.78 W m−1 K−1, which is about 10 times higher than that of the composites with disorderly distributed GNPs (1.14 W m−1 K−1). The rotating magnetic field facilitated the alignment of GNPs and increased face-to-face contact between adjacent GNPs, which significantly boosted the through-plane thermal conductivity of the composite. The compressive modulus of the CVGNPs/PVA composites was only 1.06 MPa, and it helped to reduce the thermal interface resistance to 49 mm2 K W−1. These results offer a novel approach for preparing excellent TIMs that could be used in various applications.

Environment-adaptive, anti-fatigue thermal interface graphene foam

The rapid development of high-power and high-frequency devices in electronics leads to the urgent demands for advanced thermal interface materials (TIMs) with both superior thermal conductivity and excellent structural stability. Many attempts have exploited the silicone-based TIMs with higher thermal conductive fillers, however, their structural stability remains challenging in some extreme conditions. Here we fabricate the carbon-based graphene foam roll (GFR) as flexible TIM by hydroplastic foaming (HPF) and interface strengthening methods. The enhanced interface bonding within GFR by impregnation of graphene oxide (GO) enables its superior structural integrity. It can keep mechanical stability after 10,000 cycles at a compressive strain of 60% and sustain high temperature up to 500 °C, which has never been realized in previous reports. We demonstrate the GFR-TIM not only achieves very high structural stability but also exhibits higher thermal conductivity (∼17.42 W/mK) than most commercial TIMs (5–10 W/mK). The GFR-TIM can serve as an efficient heat-dissipation component for the CPU and shows superior cooling efficiency compared to commercial TIMs. Our work provides an advanced graphene-based TIM with excellent environment-adaptive and anti-fatigue properties, broadening their application in extreme environments, such as hypersonic vehicles, high-throughput satellites and high-power radar systems.

Improved Electrical and Thermal Conductivities of Graphene–Carbon Nanotube Composite Film as an Advanced Thermal Interface Material

Thermal management has become a crucial issue for the rapid development of electronic devices, and thermal interface materials (TIMs) play an important role in improving heat dissipation. Recently, carbon−based TIMs, including graphene, reduced graphene oxide, and carbon nanotubes (CNTs) with high thermal conductivity, have attracted great attention. In this work, we provide graphene−carbon nanotube composite films with improved electrical and thermal conductivities. The composite films were prepared from mixed graphene oxide (GO) and CNT solutions and then were thermally reduced at a temperature greater than 2000 K to form a reduced graphene oxide (rGO)/CNT composite film. The added CNTs connect adjacent graphene layers, increase the interlayer interaction, and block the interlayer slipping of graphene layers, thereby improving the electrical conductivity, through−plane thermal conductivity, and mechanical properties of the rGO/CNT composite film at an appropriate CNT concentration. The rGO/CNT(4:1) composite film has the most desired properties with an electrical conductivity of ~2827 S/cm and an in−plane thermal conductivity of ~627 W/(m·K). The produced rGO/CNT composite film as a TIM will significantly improve the heat dissipation capability and has potential applications in thermal management of electronics.

Joint‐Inspired Liquid and Thermal Conductive Interface for Designing Thermal Interface Materials with High Solid Filling yet Excellent Thixotropy

AbstractFor advanced thermal interface materials (TIMs), massive inorganic addition for high isotropic thermal conductivities conflicts with suitable rheological viscosity for low contact thermal resistance. Traditional strategies rarely resolve such a contradiction, and it remains an academic and industrial challenge. Herein, inspired by the structure and function of the bone joint, a best‐of‐both‐worlds approach is reported that endows a standard polydimethylsiloxane/alumina (PDMS/Al2O3) TIM with simultaneously enhanced rheological mobility and thermal conductivity. It is conducted by employing morphology‐controllable gallium‐based liquid metal (LM) to the surface of Al2O3by a scalable mechanochemical process. At the typical polymer‐LM‐Al2O3interface, LM droplets with low cohesive energy can release the freedom for macromolecular chain relaxation and reduce the viscosity, successfully allowing the high‐loading TIMs (79 vol.%) to keep the thixotropic state and effectively reducing its contact thermal resistance with a copper substrate by 65%. At the same time, adjacent LMs merge to thermally bridge separate Al2O3particles, which facilitates the interfacial thermal conduction and enhances the thermal conductivity from 5.9 to 6.7 W m−1 K−1. Along with additional electrical insulation, this filler modification strategy is believed to inspire others to develop high‐performance polymer‐based TIMs for future advanced electronics.

Isotropically Ultrahigh Thermal Conductive Polymer Composites by Assembling Anisotropic Boron Nitride Nanosheets into a Biaxially Oriented Network.

The demand for thermally conductive but electrically insulating materials has increased greatly in advanced electronic packaging. To this end, polymer-based composites filled with boron nitride (BN) nanosheets have been intensively studied as thermal interface material (TIM). However, it remains a great challenge to achieve isotropically ultrahigh thermal conductivity in BN/polymer composites due to the inherent thermal property anisotropy of BN nanosheets and/or the insufficient construction of the 3D thermal conductive network. Herein, we present a high-performance BN/polymer composite with a biaxially oriented thermal conductive network by a dendritic ice template. The composite exhibits both ultrahigh in-plane (∼39.0 W m-1 K-1) and through-plane thermal conductivity (∼11.5 W m-1 K-1) at 80 vol % BN loading, largely exceeding those of reported BN/polymer composites. In addition, our composite as a TIM shows higher cooling efficiency than that of commercial TIM with up to 15 °C reduction of the chip temperature and retains good thermal stability even after 1000 heating/cooling cycles. Our strategy represents an effective approach for developing advanced thermal interface materials, which are greatly demanded for advanced electronics and emerging areas like wearable electronics.

Recent Advances in Thermal Interface Materials for Thermal Management of High-Power Electronics

With the increased level of integration and miniaturization of modern electronics, high-power density electronics require efficient heat dissipation per unit area. To improve the heat dissipation capability of high-power electronic systems, advanced thermal interface materials (TIMs) with high thermal conductivity and low interfacial thermal resistance are urgently needed in the structural design of advanced electronics. Metal-, carbon- and polymer-based TIMs can reach high thermal conductivity and are promising for heat dissipation in high-power electronics. This review article introduces the heat dissipation models, classification, performances and fabrication methods of advanced TIMs, and provides a summary of the recent research status and developing trends of micro- and nanoscale TIMs used for heat dissipation in high-power electronics.

Broadly manipulating the interfacial thermal energy transport across the Si/4H-SiC interfaces via nanopatterns

Manipulating the thermal transport across the interfaces via nanostructuring is critical for thermal management in electronics and energy conversion in thermoelectrics. Recent experiments have enabled the fabrication of controllable nanopatterns at interfaces, and therefore provide a new perspective to design and manipulate interfacial heat transfer. By performing nonequilibrium molecular dynamics simulations, we reported that the interfacial thermal conductance of Si/4H-SiC interfaces can be modulated broadly from ∼ 300 MW/m2K to ∼ 1000 MW/m2K by confining nanopatterns with a thickness on the order of nanometers, i.e., smaller than 30 nm. Based on the spectral heat current and participation ratio analysis, the nonmonotonic nanopattern section-dependent thermal conductance as observed in our simulations was found to be originated from two competing mechanisms, i.e., phonon-boundary scattering and interfacial phonon transport channels. The corresponding interfacial thermal conductance initially decreased with the nanopattern section when the phonon-boundary scattering is dominant and became stronger, and then increased when there were many more possible interfacial phonons transport channels. The thermal conductance was enhanced by ∼11% compared to that of the bare Si/4H-SiC interface once the latter mechanism was dominant. Besides, the thermal resistance induced by the pattern itself becomes evident and must be considered when the height of the nanopattern becomes greater. Our work here provides a comprehensive investigation on manipulating the thermal transport across the interfaces via controllable nanopatterns, which is important and meaningful for designing and optimizing the advanced thermal interface materials.

Development of Nanostructured-based Composites as Advanced Thermal Interface Materials

Thermal management is one of the most critical issues in electronics due to increasing power densities. This problem is getting even worse for small and sophisticated devices due to air gaps present between the heat source and heat sink. Thermal interface materials (TIM) are used to reduce the air gaps and significantly increase the heat transfer capability of the system. A high-thermal-performance, cost-effective and reliable TIM would be needed to dissipate the generated heat, which could enable significant reductions in weight, volume and cost of the thermal management system. In this study a number of different nanostructured materials are reviewed for potential use as a filler material in our effort to develop advanced TIM composite. Some of the candidate filler materials considered is Carbon Nanotubes, Graphene and Few Layer Graphene (FLG), Boron Nitride Nanotubes (BNNT) and Boron Nitride Nanomesh (BNNM) and Boron Arsenide (BAs). Objective is to identify composition of boron arsenide as filler in polymer-nanostructured material composite TIM for high heat flux applications. In order to design boron-arsenide-based TIM composite with enhanced effective thermal conductivity, a number of metallic and nonmetallic base-filler material composites are considered with varying filler fractions. Empirical mixture models based on effective medium theories (EMT) are evaluated for estimating effective conductivity of the two-component boron arsenide-filler composite TIM structure.

Dramatic enhancement of interfacial thermal transport by mass-graded and coupling-graded materials

With the dimension of materials shrinking into nanoscale, there has been growing interest in the Kapitza resistance which inhibits overall thermal transport. In this work, using the non-equilibrium Green's function method, we systematically investigate the optimized interfacial couplers with various gradient materials for phonon transport across one-dimensional atomic hetero-junction models. Relative to the optimized homogenous couplers, the mass-graded or coupling-graded structures are found to be applicable to improve the interfacial thermal conductance of two lead materials with both mismatched impedance and mismatched cutoff frequencies. For the couplers with both geometric graded mass and geometric graded coupling, the interfacial thermal conductance can be maximum enhanced (nearly up to sixfold enhancement on interfacial thermal conductance compared to the optimized homogenous case). The underlying mechanism of phonon transport enhancement by the optimized coupler is investigated by the phonon transmission coefficient: on the one hand, this kind of coupler is able to maximally suppress the destructive interference for transmitted phonon waves; on the other hand, the constructive interference for the transmitted phonon is also largely improved. Our findings may offer guidance for advanced thermal interface materials design.

Controllable Ag-rGO heterostructure for highly thermal conductivity in layer-by-layer nanocellulose hybrid films

Many researchers have attempted to address the problem of frequency reduction or overheating damage caused by inadequate thermal conductivity of substrates. Developing advanced, green, and practical thermal interface materials (TIMs) is one of the most promising solutions to date. Herein, a facile method is proposed to achieve fascinating thermal conductivity of TIMs via constructing two-dimension (2D) reduced graphene oxide (rGO) decorated with zero-dimension (0D) silver nanoparticles (AgNPs) in hybrid nanofibrillated cellulose (NFC) film. The surface morphology and chemistry of Ag-rGO-functionalized NFC (Ag-rGO/NFC) are significantly altered by adding a small amount of Ag-rGO nanosheets (9.6 wt%), resulting in remarkable improvement in the thermal conductivity. The in-plane thermal conductivity of Ag-rGO/NFC (27.55 W m−1 K−1) showed a massive enhancement of over 1095% compared to pure NFC (2.3 W m−1 K−1), accompanied by 573% increase in through-plane conductivity. These enhancements could be attributed to the robust heterostructural Ag-rGO networks and dense layer-by-layer (LBL) structures. It is likely that these controllable structures come into being due to the intense static adsorption between graphene oxide (GO) and Ag+ as well as the hydrogen bonding interaction between GO and NFC. It is worth noting that exceptionally fast heat transport is achieved for Ag-rGO/NFC in practical application, with values as high as 0.18 °C/s, in sharp contrast to 0.16 °C/s for pure NFC films in the time range of 80–220 s. This could be due to the excellent thermal conduction networks built by Ag-bridged rGO nanosheets. This work provides valuable insights into the fabrication of highly thermal conductive composites in the promising field of electronic equipment, integrating intelligent functionality and environmental compatibility.

Metal-Level Thermally Conductive yet Soft Graphene Thermal Interface Materials.

Along with the technology evolution for dense integration of high-power, high-frequency devices in electronics, the accompanying interfacial heat transfer problem leads to urgent demands for advanced thermal interface materials (TIMs) with both high through-plane thermal conductivity and good compressibility. Most metals have satisfactory thermal conductivity but relatively high compressive modulus, and soft silicones are typically thermal insulators (0.3 W m-1 K-1). Currently, it is a great challenge to develop a soft material with the thermal conductivity up to metal level for TIM application. This study solves this problem by constructing a graphene-based microstructure composed of mainly vertical graphene and a thin cap of horizontal graphene layers on both the top and bottom sides through a mechanical machining process to manipulate the stacked architecture of conventional graphene paper. The resultant graphene monolith has an ultrahigh through-plane thermal conductivity of 143 W m-1 K-1, exceeding that of many metals, and a low compressive modulus of 0.87 MPa, comparable to that of silicones. In the actual TIM performance measurement, the system cooling efficiency with our graphene monolith as TIM is 3 times as high as that of the state-of-the-art commercial TIM, demonstrating the superior ability to solve the interfacial heat transfer issues in electronic systems.

A Review of the Performance and Characterization of Conventional and Promising Thermal Interface Materials for Electronic Package Applications

Thermal interface materials (TIMs) play a key role in reducing thermal resistance between jointed solid surfaces in order to increase thermal transfer efficiency. A TIM is a thermally conductive material which is applied between the interfaces of two components (such as circuit board and heat sinks) to enhance the thermal conductance between them. The present paper provides a detailed review in order to characterize conventional and advanced TIMs in terms of thermal performance. The paper also discusses the measurement of TIM performance using different techniques. It was found that greases are the most widely used TIMs and offer thermal resistance in the range of 0.1–1 cm2°C/W. However, greases are messy and difficult to apply and remove due to their high viscosity. Moreover, they have reliability issues such as pump-out, phase separation and dry-out, which limits their use as an efficient TIM. The thermal resistance of TIMs which contain carbon nanotubes (CNT) fall in the range of 0.01–0.19 cm2°C/W. However, the use of CNT as a TIM at high temperatures does not allow for uniform distribution of heat on cooling of electronic packaging systems. Although TIMs with the addition of nano--metal particles are considered promising, it is necessary to carry out extensive research on CNT as a TIM.