Thermal Conductivity Of Epoxy Research Articles

Thermal conductivity of epoxy resin films doped with a polythiophene/graphene complex or aluminum nitride

AbstractPolymer composites with thermal conductivity are attractive for heat dissipation in electronic devices. We prepared epoxy resin‐based composite films filled with polythiophene [poly(3‐hexylthiophene‐2,5‐diyl)] (P3HT)/graphene complex or aluminum nitride (AlN). The composite films were characterized by electron microscopic observation, thermogravimetric analysis, and thermal conductivity measurements. The addition of a small content of P3HT/graphene complex (<1 wt%) increased both the out‐of‐plane and in‐plane thermal conductivities of the epoxy resin. The addition of AlN also increased thermal conductivity, but ≥40 wt% was required to obtain thermal conductivity comparable with that of an epoxy resin film doped with 0.9 wt% P3HT/graphene complex. The present results illustrate the potential of P3HT/graphene complexes as fillers for improving the thermal conductivity of epoxy resins without affecting their insulating properties.Highlights Polythiophene/graphene fillers increased epoxy resin films' thermal conductivity. To raise the thermal conductivity of epoxy resin films high AlN content was needed. In‐plane/out‐of‐plane epoxy resin films' thermal conductivities were evaluated.

Carbon nanotubes grafting aminated epoxy resin with improved elasticity and surface adhesion for enhanced thermal management performance

It is a great challenge to develop thermal interface materials that enable fast heat transfer between the surface of microelectronic materials and heat sinks. In this paper, multi-walled carbon nanotube/epoxy composites (EP-NH2-x) were synthesized by amidation reaction using aminated epoxy resin as matrix and carboxylated multi-walled carbon nanotubes. EP-NH2-x can reduce the interfacial thermal resistance and the promotion of phonon conduction through the chemical bonding connection between the resin and the carbon nanotubes, which will in turn improve the thermal conductivity of the composites. The thermal conductivity of EP-NH2-10 reaches 0.531 W·m−1·K−1 at a and has good variable temperature cycling stability, internal elasticity and surface adhesion. This work highlights the potential application of carbon materials to improve the thermal conductivity of epoxy resins.

Enhanced thermal conductivity of epoxy resin by incorporating three-dimensional boron nitride thermally conductive network.

Packaging insulation materials with high thermal conductivity and excellent dielectric properties are favorable to meet the high demand and rapid development of third generation power semiconductors. In this study, we propose to improve the thermal conductivity of epoxy resin (EP) by incorporating a three-dimensional boron nitride thermally conductive network. Detailedly, polyurethane foam (PU) was used as a supporter, and boron nitride nanosheets (BNNSs) were loaded onto the PU supporter through chemical bonding (BNNS@PU). After immersing BNNS@PU into the EP resin, EP-based thermally conductive composites were prepared by vacuum-assisted impregnation. Fourier transform infrared spectrometer and scanning electron microscope were used to characterize the chemical bonding and morphological structure of BNNS@PU, respectively. The content of BNNS in BNNS@PU/EP composites was quantitatively analyzed by TGA. The results show that the thermal conductivity of the BNNS@PU/EP composites reaches 0.521 W/m K with an enhancement rate η of 30.89 at an ultra-low BNNS filler content (5.93 wt. %). Additionally, the BNNS@PU/EP composites have excellent dielectric properties with the frequency range from 101 to 106Hz. This paper provides an interesting idea for developing high thermal conductivity insulating materials used for power semiconductor packaging.

Thermally conductive h-BN/EP composites oriented by AC electric field induction

The excellent electrical insulation properties and mechanical properties of epoxy resin (EP) have led to its rapid development in the field of microelectronic packaging. However, the poor thermal conductivity of epoxy resins (thermal conductivity of only 0.14 W/(m·K)) limits the development of components for high power. Adding h-BN to epoxy resin to prepare composites can effectively improve the thermal conductivity of epoxy resin. In this paper, h-BN/EP high thermal conductivity composites were prepared by means of AC electric field induction with the goal of making the composites low loading and high thermal conductivity (loading of 10 wt%). It was shown that the h-BN/EP composite had the highest thermal conductivity of 0.310 W/(m·K) when applied to an AC electric field of 120 V/mm and 50 Hz for 1 h. It was 2.214 times higher than that of EP and 1.325 times higher than that of the same-loaded h-BN/EP composite (0.234 W/(m·K)). A thermal conductivity model that can predict the thermal conductivity of composites prepared using the same type of method is also developed, which extends the applicability of the thermal conductivity model. The prepared composites have good thermal management capability. The method is easy to be engineered and has great potential for use in electronic packaging and even other high thermal conductivity applications.

Highly thermal conductive epoxy composites enabled by 3D graphene/Cu-based dual networks for efficient thermal management

With the increasing integration of electronic devices, efficient thermal management is urgently required. Herein, 3D graphene/Cu-based dual networks were developed for highly thermal conductive epoxy (Cu@hLIG/EP) composites. Using the honeycomb-like porous laser-induced graphene (hLIG) as 3D skeleton, the Cu layer was introduced by electroless plating. The Cu@hLIG/EP composite showed a high thermal conductivity up to 16.4 W m−1 K−1, which was almost 63 times that of neat EP and 6 times that of hLIG/EP composite with similar filler loading. This increase was attributed to the pre-constructed 3D network, phonon-electron dual thermal transfer channels and reduced phonon mismatch in composites. Furthermore, by using the reprocessable EP resin, the designability of thermal conductive composites was greatly enhanced, where layered composites could be easily fabricated by the simple stacking strategy. The material/process developed demonstrates wide promise in thermal management applications.

Copper Modified Boron Nitride And Graphene Combined To Self-Assemble Three-Dimensional Thermal Conductivity Framework to Improve the Thermal Conductivity of Epoxy Resin

Copper Modified Boron Nitride And Graphene Combined To Self-Assemble Three-Dimensional Thermal Conductivity Framework to Improve the Thermal Conductivity of Epoxy Resin

Effect of N–Ni coordination bond on the electrical and thermal conductivity of epoxy resin/nickel‐coated graphite

AbstractThe agglomeration of nickel‐coated graphite (NCG) in epoxy resin (EP) composites leads to low electrical conductivity of EP composites, which limits their development in electronic devices and multilayer circuits. In order to improve the electrical and thermal conductivity of NCG/EP composites, ethylenediamine (EDA) was used to modify NCG and compared with pure NCG‐filled EP composites. It was found that the conductive effect of modified composites with 20 wt% filler is better than that of unmodified composites with 40 wt% filler. The results of Fourier transform infrared spectroscopy and thermogravimetric analysis of EDA‐modified NCG (ENCG) showed that a coordination adsorption reaction occurred between EDA and NCG, forming N–Ni coordination bonds. When the filling amount of ENCG was 40 wt%, the conductivity and thermal conductivity of the composite are improved most significantly. The volume resistivity was reduced from 2.636 to 0.109 Ω cm, a decrease of 95.85%, and the thermal conductivity was improved from 0.517 to 0.968 W/(m K), an increase of 87.23%, respectively. Meanwhile, ENCG has better dispersion in the EP matrix than NCG.

Effect of small-sized modifier on boron nitride for efficient heat transfer through thermal conductive epoxy composites

Surface modification of a crystalline filler is a powerful method for increasing the thermal conductivity (κ) of filler-impregnated composites. Herein, boron nitride (BN) filler was functionalized with cationic molecules of different sizes to directly recognize the effect of an amorphous area on the filler-polymer matrix interface. Measured thermal conductivity and temperature rise for a polymer composite was up to 67.1 % and 15.3 % greater, respectively, in the sample to which the smallest molecule-modified BN was added, compared to the comparable sample with free BN. The smaller the size of the modifier molecule, the better it bonds with the resin and the smaller the non-crystalline area. Such changes improve the heat transfer at the interface by reducing interfacial thermal resistance. These findings can serve as a reference to develop alternative and effective strategies for filler modification, an alternative approach instead of focusing on functional groups and modifiers.

The Enhancement of the Thermal Conductivity of Epoxy Resin Reinforced by Bromo-Oxybismuth.

With the gradual miniaturization of electronic devices, the thermal conductivity of electronic components is increasingly required. Epoxy (EP) resins are easy to process, exhibit excellent electrical insulation properties, and are light in weight and low in cost, making them the preferred material for thermal management applications. In order to endow EPs with better dielectric and thermal conductivity properties, bromo-oxygen-bismuth (BiOBr) prepared using the hydrothermal method was used as a filler to obtain BiOBr/EP composites, and the effect of BiOBr addition on the properties of the BiOBr/EP composites was also studied. The results showed that the addition of a small amount of BiOBr could greatly optimize the dielectric properties and thermal conductivity of EP resin, and when the content of BiOBr was 0.75 wt% and 1.00 wt%, the dielectric properties and thermal conductivity of the composite could reach the optimum, respectively. The high dielectric constant and excellent thermal conductivity of BiOBr/EP composites are mainly due to the good layered structure of BiOBr, which can provide good interfacial polarization and thermal conductivity.

The fabrication of a boron nitride/ammonium polyphosphate skeleton based on ice template method for thermal conductive and flame retardant epoxy

Epoxy (EP) is widely used in the field of high-speed communication and microelectronics. However, its poor thermal conductivity and high flammability bury the hidden danger of fire accident. In this work, the hexagonal born nitride (h-BN) combined with ammonium polyphosphate (APP) constructs a three-dimensional skeleton (3D-BN) via bidirectional freezing technology. The 3D-BN skeleton is immersed into the EP matrix to obtain the EP/3D-BN composite, which is endowed with high thermal conductivity and flame retardancy. When the loading of hexagonal born nitride (h-BN) is 9.1 vol%, the thermal conductivity of EP/3D-BN3 composite reaches 1.67 W m−1 K−1, which is increased by 944 % compared with that of the control EP. The peak heat release rate (PHRR) and total heat release (THR) of EP/3D-BN3 are significantly reduced by 54 % and 34 % respectively. This EP/3D-BN composite provides potential applications toward the industrial production for microelectronic devices.

Construction of three-dimensional interconnected boron nitride/sliver networks within epoxy composites for enhanced thermal conductivity

With the advent of the 5G era, the conspicuous increases in operating power and thermogenic capacity of integrated electronic components necessitated the development of enhanced thermal conductive polymeric composites with excellent heat dissipation properties. Herein, the polydopamine (PDA) and silver (Ag) modified BN (BN-PDA-Ag) was synthesized and a three-dimensional (3D) interconnected BN-PDA-Ag porous network was successfully fabricated by the salt template-assisted method to improve the thermal conductivity property of epoxy based composites. The high thermal conductive epoxy resin composites (3D BN-PDA-Ag/EP) were obtained by infiltrating epoxy into the 3D BN-PDA-Ag porous network. On one hand, the 3D BN-PDA-Ag porous skeleton provided continuous transfer paths for phonons, which was conducive to reducing phonon scattering. On the other hand, the Ag nanoparticles loaded on the BN surface bridged the adjacent BN sheets, significantly decreasing the thermal contact resistance between adjacent fillers. The isotropic thermal conductivity (TC) of 3D BN-PDA-Ag/EP composite with a BN-PDA-Ag content of 20.3 wt% reached 1.37 W/(m·K), which exhibited a evident enhancement of 661% compared with pure epoxy. The thermal management simulation and application results showed the composite had enormous application potential for electronic devices and components in heat dissipation.

Preparation of molybdenum disulfide microspheres and their effect on the thermal conductivity of epoxy resin

Preparation of molybdenum disulfide microspheres and their effect on the thermal conductivity of epoxy resin

Improving inherent thermal conductivity of epoxy resins based on contribution components of thermal conductivity: A molecular dynamics study

The inherent thermal transport properties of epoxy resin are vital factors to be studied in applications. In the present work, we constructed the amorphous crosslinking structure, the step crosslinking structure and the ordered crosslinking structure based on molecular dynamics theory, and used the reverse nonequilibrium molecular dynamics (RNEMD) method to calculate the thermal conductivity (TC) of different structures. Based on the numerical verification of the reliability of the method, the contribution of bonding to the TC was enhanced by increasing the molecular arrangement orderliness to reduce phonon scattering, taking the composition of the TC contribution as the guide. Meanwhile, the contribution of non-bonding interaction to the TC was enhanced by using compression process to achieve TC increase in the epoxy resin intrinsic structure, followed by exploring the effect of cross-linking degree on the TC of different structures. The results showed that the TC of amorphous epoxy resin decreased with the increase of crosslinking degree, and the relative high-frequency VDOS increased, but the influence of crosslinking degree on TC was minor in the range. For amorphous epoxy resin four-sided pressurization varied in the range of 0–7 Gpa, the non-bond energy percentage increased in the range of 0–60%, and the increase of non-bond energy made its contribution to TC increased significantly. The epoxy resin achieved 215% improvement in intrinsic TC by changing the molecular arrangement orderliness. The ordered structure TC varied from 0.3 to 3.5 W/(m⋅K) in the pressure variation range of 0–7 GPa. As the structure becomes more ordered, the TC increased significantly with the degree of cross-linking. The study provided the theoretical basis for the realization of resin preparation and resin thermal property evaluation with regulated intrinsic TC.

Review of thermal conductivity in epoxy thermosets and composites: Mechanisms, parameters, and filler influences

Rapid development of energy, electrical and electronic technologies has put forward higher requirements for the thermal conductivities of epoxy resins and their composites. However, the thermal conductivity of conventional epoxy resins is relatively low, which could cause major heat dissipation issues. Therefore, the thermal conductivity enhancement of epoxy resins has long been a hot research topic in both academia and industry. In recent years, many promising advances have been made at the technical and mechanistic levels. This review includes the different approaches, the thermal conduction mechanisms implied, and the main research progresses. The research and academic achievements are mainly focused on the development of intrinsically liquid crystal epoxy resins and their composites, and the addition of fillers on amorphous epoxy resins. Finally, the challenges and prospects for thermal conductive epoxy resins are provided. Notably, this review can provide a more comprehensive understanding of thermally conductive epoxy resins and a guideline for the cutting-edge development direction of thermally conductive epoxy resins.

Ultrahigh in-plane thermal conductive epoxy composites by cellulose-supported GnPs@PDA skeleton under stress-induced orientation strategy

Designing anisotropic thermally conductive networks in thermal management materials can effectively exploit the high in-plane thermal conductivity of two-dimensional fillers to achieve high heat transfer efficiency along the predetermined direction, which is the hotspot for thermal management materials. However, constructing such an interconnected network with an orderly alignment structure through thermally conductive fillers has proved challenging. In this study, a high-density cellulose-supported GnPs@PDA skeleton with an interconnected and ordered structure was successfully prepared through the stress-induced strategy. After embedding into the epoxy resin, the EP/CGP composites with 22.1 vol% filler content exhibit an excellent in-plane thermal conductivity of 8.39 W/mK under a 75 % compression ratio, which is 12.3 times higher than that without compression. The enhancement of thermal conductivity for EP/CGP composites under the stress-induced orientation strategy is illustrated by the finite element analysis and metal foam theory. Furthermore, the transient heat transmission processes of the composites are recorded to verify their prospect in thermal management applications. This novel approach sheds light on the fabrication of thermally conductive networks with interconnected and ordered structures for next-generation thermal management materials.

An Integrated Multi-Functional Thermal Conductive and Flame Retardant Epoxy Composite with Functionalized Carbon Nitride Nanosheets.

In miniaturized and integrated electronic devices, thermal potential and fire hazards caused by heat diffusion require an efficient thermal management system with versatile electronic packaging equipment. The flame retardancy was endowed on the surface of carbon nitride after thermal etching (CNNS) containing piperazine pyrophosphate (PPAP) by hydrogen bonding, and the obtained nanosheet was defined as PPAP-CNNS. During solution blending and program-controlled curing, PPAP-CNNS was used as a multifunctional filler to fabricate highly thermoconductive and fire retardant epoxy resin (EP) composites. In line with expectations, the resultant EP composites containing 7 wt% PPAP-CNNS had an exceptional thermal conductivity (TC) of 1.1 W·m-1K-1, which was 4.8 times higher than pure EP. Simultaneously, there was a sharp drop in the heat release rate (HRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP) compared to pure EP. These reductions were, respectively, 63.7%, 54.2%, 17.9%, and 57.2%. The addition of PPAP-CNNS increased the specific surface area, which increased the heat conduction routes, and also the shape of the compact and solid char layer during burning, protecting the underlying polymer. These improvements to dispersion and surface functionalization were made possible by the compound. These results indicate that the preparation of integrated multi-functional resin described in this study has a wide application.

Three-dimensional insulating framework construction for achieving high thermal conductivity epoxy composites with superior dielectric properties

With the trend of modern electronic device miniaturization and higher power density, polymer composites with both high thermal conductivity and excellent dielectric properties are highly desirable. In this work, a homogeneous, porous, and insulating Si3N4w@SiO2 framework was prepared using silicon nitride nanowires (Si3N4w) by a polystyrene (PS) template method modified with fumed silica (SiO2). After infiltration, the thermal conductivity of the epoxy/3D-Si3N4w@SiO2 composites reached 1.05 W/m·K at the loading of 7.80 vol% (5.25 times higher than pure EP), and showed good thermal stability. In addition, the dielectric properties of the composites were systematically investigated. The composites show excellent dielectric properties, which can maintain dielectric constant below 5.5 and loss tangent below 0.05 in a wide frequency range (>1 Hz), temperature range(<120 °C) and under high electric field intensity (106 V/m). These results demonstrate the potential of Si3N4w for application in electronic packaging materials and provide a simple preparation strategy.

Controllable preparation of boron nitride microspheres and their epoxy-based thermoconductive composites

How to prepare spherical boron nitride (BN) particle with different size is an extremely challenging work. In this paper, the controllable preparation of spherical BN particle from nanospheres to microsphere was realized by changing the synthesis temperature of trimethyl borate (B(OMe)3) and ammonia. The spherical precursor (SP) with high oxygen content was obtained first, and then it was heated under flowing ammonia atmosphere to form stable boron nitride microspheres (BNMS). The BNMS exhibits onion-like cavitation structure with a diameter of 0.8–3.4 μm. The effects of the lower reaction temperature (700–825 °C) and gas flow rate on the spherical precursor are discussed. A possible mechanism is proposed to explain the formation of precursors and the appearance of onion-like structure. It is believed that the formation of microsphere is due to the deposition and growth of BO species during the flow process of nanosphere. In addition, the effect of the addition of BNMS on the thermal conductivity of epoxy resin (EP) composites was investigated.

SiC Nanowires Bridged Graphene Aerogels with a Vertically Aligned Structure for Highly Thermal Conductive Epoxy Resin Composites and Their Mechanism

Thermal conductive composites have a wide application in the electronic packaging field, and fabricating three-dimensional (3D) graphene aerogels by the self-assembly method is a facile way to construct thermal conductive networks in polymer composites. But those self-assembled graphene aerogels can only endow composites with a limited thermal conductivity because (1) abundant defects on RGO sheets reduce their intrinsic thermal conductivity and (2) massive edges and gaps in aerogels cause severe phonon scattering. Many works before have been done to heal the defects by high-temperature annealing, but the works of filling gaps and decreasing phonon scattering are rare. Herein, we designed a facile route to synthesize SiC nanowires on the edges of RGO sheets for connecting adjacent RGO sheets, decreasing phonon scattering, and enhancing thermal conduction efficiency in graphene aerogels. Before that, RGO/Si aerogels with vertically aligned structures were obtained by the chemical reduction method and the freeze-drying method to enhance their through-plane thermal conduction efficiency. When the initial mass ratio of GO solute/silicon powder was 5:1, HGA-5 endowed the EP composite with a high through-plane thermal conductivity of 3.59 W m–1 K–1 at a relatively low filler loading of 2.87 wt %. Finite element analysis was applied to illustrate the thermal conductive mechanism of the hybrid aerogels-filled EP composites. The EMI shielding performance of the composites was also discussed in this work.

Preparation of highly thermally conductive epoxy composites featuring self‐healing and reprocessability

AbstractEnhancing the thermal conductivity of epoxy resin is an urgent demand for its application in electronic packaging field. In this work, thermally conductive epoxy/graphite composite featuring excellent self‐healing and reprocessability is prepared based on covalent adaptable networks. The effect of graphite on the rheology, reprocessing, and self‐healing properties of epoxy have been studied. The result shows that the prepared composites can be easily reprocessed and have excellent self‐healing property. On the fundamental of the highly multifunctional performance of the epoxy composites, highly thermally conductive bulk composites are constructed via multilayered stacking up and self‐healing based on the film composites, which is prepared using a rolling method. It is demonstrated that the films can assemble into new substance bulk by stacking up through self‐healing. The high thermal conductivity is achieved by the highly aligned graphite induced by the rolling process. Result reveals that, being filled with 50% mass fraction of GR, the bulk composites possesses high thermal conductivity of 8.411 Wm−1 K−1. This work provides a new strategy to prepare recyclable and highly thermally conductive epoxy.