Thermal Conductivity Of Epoxy Research Articles

Synergy between biphenyl mesomorphic structure and organic crystal phenazine for improving the intrinsic thermal conductivity of epoxy

The inherent low intrinsic thermal conductivity of epoxy resin severely restricts its potential application, making it difficult to meet the growing demand of energy, electrical and electronic technologies. The liquid crystal epoxy resin, which is wildly employed to improve the intrinsic thermal conductivity of epoxy resin, is constrained by its complex molecular structure design and synthesis procedures. In this work, the rigid group of 4,4’-dihydroxybiphenyl was introduced into the main chain of epoxy resin by ring-opening polymerization (ROP) to change the molecular structure of epoxy resin. The introduction of biphenyl groups enhances the orderliness of molecular structure and forms hydrogen bonds between molecules, which further enhances the transport of intramolecular phonons. The thermal conductivity of the graft modified epoxy resin (GMR) after DDM curing is 0.30 W·m-1·K-1. After adding of organic crystal phenazine (PNE) to the GMR matrix, the inherent strong crystallization behaviors of PNE can accelerate the regularity arrangement of rigid groups in GMR, and promote the nucleation and crystallization process of GMR/PNE. The thermal conductivity of GMR/PNE after DDM curing can reach 0.33 W·m-1·K-1. It is 165% of the thermal conductivity of traditional epoxy resin, which is 0.2 W·m-1·K-1. This study will provide a new method to improve the intrinsic thermal conductivity of polymer materials.

Interface engineering of MXene towards highly fire-safe epoxy resin with enhanced thermal conductivity

The integration of superior flame retardancy and enhanced thermal conductivity of epoxy resins (EP) is highly desirable for practical applications. Herein, novel organophosphorus-decorated MXene hybrid flame retardant (PMXene) was prepared by the interface engineering between melamine diphenylphosphinate (MDP) and two-dimensional titanium carbide (MXene). With the loading of 6.0 wt% PMXene, the EP/6.0PMXene material achieved a V-0 rating during the UL 94 testing besides the high limiting oxygen index (35.2 %). Cone calorimetric results revealed that the peak of heat release, peak of smoke release rate and smoke factor values of EP/6.0PMXene were reduced by 36.6 %, 27.6 % and 48.7 %, respectively, in comparison with those of pristine EP. Besides, the PMXene hybrid enhanced the thermal conductivity of EP to 0.38 W/m·K, a 52.6 % improvement over pristine EP. Thus, this work provides a novel strategy for fabricating thermosetting materials with high fire-safety and enhanced thermal conductivity.

Constructing house-of-cards-like networks with BNNS confined in interlocking Al2O3 platelet skeletons for thermally conductive epoxy composites

The construction of 3D filler networks is an effective strategy to improve the thermal conductivity of epoxy resins, yet it is still severely limited by the disconnection of conduction channels. In this contribution, an original interlocking hybrid skeleton with continuous conduction channels was developed by assembling BNNS into an in situ-formed interlocking Al2O3 platelet skeleton using commercial polyurethane as a template, where large intergranular contact areas of Al2O3 platelets were established by sintering to greatly decrease the contact thermal resistance. Besides, the interlocking Al2O3 skeleton coupled with BNNS under hydrogen bonding endowed further improvement of its thermal conductivity. The optimized Al2O3/BNNS/EP composite displayed an excellent thermal conductivity of 5.01 W/mK at 15.3 vol% of Al2O3 and 11.4 vol% of BNNS loading, far higher than that of neat epoxy resin by 1904.0 %. Meanwhile, the interlocking hybrid skeleton provided the epoxy resin with low dielectric loss, satisfactory thermal stability and flame retardancy.

Boron nitride nanosheets synergized with two‐dimensional micron silver sheets to enhance thermal conductivity and insulation of epoxy resin composites

AbstractWith the rapid progress of the advanced electronic device industry, precision electronic instruments are gradually developing towards miniaturization. In this case, epoxy resin gradually attracts people's attention, but its intrinsic thermal conductivity is not high, and the resulting heat dissipation problem limits the further application of epoxy resin in the field of electronic packaging. Therefore, how to enhance the thermal conductivity of epoxy resins has become an urgent problem in the field of electronic packaging. In this work, BNNS was successfully prepared by stripping h‐BN into a flaky two‐dimensional material, which was added to the epoxy resin as a filler to make the composite material. And on the basis of the above, two‐dimensional micron silver flakes (AgMS) with different mass fractions were added to the composites, and the AgMS/BNNS/EP composites were successfully prepared. When BNNS was 25 wt% and AgMS was 1 wt%, its out‐of‐plane thermal conductivity was enhanced from 0.17 W m−1 K−1 of pure epoxy resin to 0.43 W m−1 K−1. When BNNS was 20 wt% and AgMS was 1 wt%, the breakdown strength was enhanced from 105 kV/mm for pure epoxy to 130 kV/mm. This work provides a new strategy for synthesizing high‐thermal‐conductivity epoxy matrix composites.

Research on Improving the Thermal Conductivity of Epoxy Resin with Flexible Assisted Rigid Groups

Research on Improving the Thermal Conductivity of Epoxy Resin with Flexible Assisted Rigid Groups

A processable high thermal conductivity epoxy composites with multi-scale particles for high-frequency electrical insulation

The solid-state transformer (SST) in the renewable energy grid is developing in the way of high voltage and high frequency, which often results in a sharp increase in heat production of the equipment and accelerates the failure of the insulating materials. Epoxy resin (EPR) is commonly used as an insulation material for SST due to its excellent electrical insulating properties, processing performance (viscosity), and low price. However, the thermal conductivity of EPR is only about 0.2 W/(m·K), which leads to poor insulating performance under high frequency and temperature. To enhance thermal conductivity, a substantial quantity of highly thermally conductive particles is incorporated into the EPR, accompanied by a severe increase in electrical insulation defects and viscosity. This study utilized a multi-scale particle-filled approach to investigate the thermal conductivity, processing characteristics, and high-frequency electrical insulation performance of composites. The composite, filled with 25 µm BN and 5 µm SiO2 particles, enhances thermal conductivity to 0.732 W/(m·K) and demonstrates superior electrical insulating properties at both 10 kHz and 20 kHz bipolar square waves (with an increase of 131.76% and 163.97% in relative EPR, respectively), as well as good processability. Meanwhile, it is found that the dielectric loss, thermal conductivity, and electric field distribution of the composite are the main factors affecting the electrical insulating properties from 10 to 20 kHz under high voltage.Graphical

Excellent thermal conductive epoxy composites via adding UHMWPE fiber obtained by hot drawing method

AbstractThe continuous updating and iteration of electronic devices brings about a significant accumulation of heat. It is urgent to enhance the thermal properties of polymer‐based composites to alleviate the heat dissipation problem in the microelectronics industry. In this paper, the hot drawing process was introduced to increase the crystallinity of ultra‐high molecular weight polyethylene (UHMWPE) fiber and improve its thermal conductivity. The ultra‐high molecular weight polyethylene fiber/epoxy resin (UHMWPE fiber/Epoxy) composites with high thermal conductivity were prepared by compositing UHMWPE fiber with epoxy resin under vacuum conditions. Due to the good crystallinity of the UHMWPE fiber (86%), an efficient thermal conduction path is provided for phonons in the axial direction along the fibers. The results show that the thermal conductivity of the composites reaches a maximum of 3.51 W/mK (in‐plane), which is 17.47 times higher than that of the epoxy resin (0.19 W/mK). The thermography pictures indicate that the composites have better heat transfer capacity with an increase in the draw ratio (λ). In addition, the composites also have the characteristics of low density and low electrical conductivity. These researches will provide a new idea for the preparation of all‐polymer composites with high thermal properties.Highlights A hot drawing process was introduced to increase the crystallinity of UHMWPE fiber for improving thermal conductivity. High crystallinity facilitates the reduction of phonon scattering and the transmission of thermal energy by phonons. The obtained polymer composites exhibit an ultra‐high in‐plane thermal conductivity.

Ternary particle composite synergistically enhances the fluidity and dielectric properties of filled thermal conductive epoxy resin

Abstract Particle-packed epoxy materials are widely used to improve the thermal conductivity of insulation materials. However, the addition of fillers increases the viscosity of the composite which reduces its operability, and is not conducive to the packaging of power electronic equipment such as electric transformers and reactors. Multi-scale particle compounding is one of the effective methods to enhance the co-processing performance of materials by reducing the friction between particles and epoxy matrix while forming an effective thermal conductivity network. Three types of spherical alumina sized around 4 μm, 38 μm, and 125 μm were used as fillers to study the fluidity, thermal conductivity, and dielectric properties of single-filled and ternary compounds. The results showed that the ternary particle composite reduced the viscosity of the precursor by up to 68.8%, achieving a synergistic improvement in operability, thermal conductivity, and electrical performance.

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