Heat Dissipation In Electronic Devices Research Articles

Multiple scattering effect of spherical LaPO4 enhanced broadband emissivity for heat dissipation of electronic devices

High-performance infrared radiation materials with excellent broadband emissivity, remarkable thermal stability, and scalable fabrication processes play a vital role in heat dissipation and energy-saving applications. However, current strategies of broadband emissivity enhancement remain inadequate. This study investigates the impact of LaPO4 morphology on the infrared radiation properties of composite coating. Three distinct morphologies (sphere, rod and mesh sheet) of LaPO4 are explored using a simulation-aided method. The composite coating filled with large-sized spherical LaPO4 particles with low diffuse reflection, exhibits a significantly enhanced infrared radiation capability, resulting in a broadband emissivity of 95.6 %. Furthermore, the composite coating achieves a large temperature reduction of 6.2 °C and high cooling efficiency of 11.9 % when subjected to a heating power of 2250 W/m2. This work provides an innovative strategy for regulating material emissivity through morphology control, benefiting advancements low-cost radiation heat transfer technology.

Record-Low thermal boundary resistance at bonded GaN/diamond interface by controlling ultrathin heterogeneous amorphous layer

Thermal boundary resistance (TBR) in semiconductor-on-diamond structure bottlenecks efficient heat dissipation in electronic devices. In this study, to reduce the TBR between GaN and diamond, surface-activated bonding with a hybrid SiOx-Ar ion source was initially applied to achieve an ultrathin interfacial layer. The simultaneous surface activation and slow deposition of the SiOx binder layer enabled precise control over layer thickness (2.5–5.3 nm) and formation of an amorphous heterogeneous nanostructure comprising a SiOx region between two inter-diffusion regions. Crucially, the 2.5-nm-thick interfacial layer achieved a TBR of 8.3 m2⋅K/GW, a record low for direct-bonded GaN/diamond interface. A remarkable feature is that the TBR is extremely sensitive to the interfacial thickness; Varying from 8.3 m2⋅K/GW to 34 m2⋅K/GW with thickness difference of only 2.8 nm. Theoretical analysis revealed the origin of this phenomena: a diamond/SiOx inter-diffusion layer extend the vibrational frequency, far exceeding that of crystalline diamond, which increases the lattice vibrational mismatch and suppresses phonon transmission.

Experimental investigation on the thermal performance of a large-size aluminum vapor chamber for multi-point heat sources

Abstract With the development of electronic information technology, the integration and power of electronic equipment continue to increase. As an efficient heat transfer element, vapor chambers are widely used in the field of heat dissipation of electronic devices. However, greater challenges have been posed in terms of higher heat dissipation capacity, larger size, and lighter weight. Therefore, a large-scale aluminum vapor chamber with a size of 340 mm×295 mm ×7.5 mm is designed for the heat dissipation of multi-point array heat sources. Multiple parallel porous ribs are sintered to form capillary wicking channels and vapor diffusion paths, which efficiently transfer the heat from the middle of the vapor chamber to the cold plate on the two sides. The transient working characteristics and heat dissipation performance under different working conditions are experimentally investigated. The results show that there is obvious temperature instability, which can be suppressed by the tilt of the vapor chamber and the increase of the heating power. Under the tilt condition, the temperature rises in the vertical direction due to the influence of gravity, while the inclination angle has basically no effect. The vapor chamber can work stably at the total heating power of 2100 W with the smallest thermal resistance 0.03 °C/W. The single-point heat flux can reach 7.3W/cm2 for the 128 heat sources. Compared to a traditional vapor chamber, the proposed aluminum vapor chamber provides a thermal management solution for large-size electronic devices with multiple heat sources.

Electrohydrodynamic characteristics in parallel-fin channels and enhanced heat transfer performance of an ionic wind heat sink

High heat flux density may lead to a decline in the performance of highly integrated electronic components, which presents a major challenge to thermal management strategies. This work developed ionic wind heat sinks with parallel-fin channels for cooling high-power chips. The study examined the effects of intake air velocity, number of electrodes, and discharge spacing on the distribution of ionic wind flow and the improved heat transfer performance of the ionic wind heat sink. The findings suggest that the ionic wind heat sink with wire electrodes perpendicular to the fin channels can withstand higher operating voltages and generate more reliable corona discharges. The improved heat transfer capabilities are achieved with reduced inlet air velocity. The heat transfer enhancement factor (HTEF) of the ionic wind heat sink decreases as the discharge spacing increases, leading to a reduction in the peak value of the body force. The heat transfer capacity declines as the number of wire electrodes increases, because marginal effects lessen disruption to the thermal boundary layer. An effective airflow is achieved when wire electrodes are positioned upstream of the heat sink and run parallel to the fins, ensuring a steady and efficient cooling process. The design effectively disrupts the thermal boundary layer, reducing momentum loss in the flow and increasing the HTEF value by 21.2%. This improvement significantly enhances the heat dissipation capacity. The structurally optimized heat sink demonstrates excellent overall performance and is a viable option for improving heat dissipation in electronic devices.

High thermal conductivity and low dielectric loss of three-dimensional boron nitride nanosheets/epoxy composites

Electronic power devices are moving towards high frequency, high integration, and high power, which urgently needs to develop high thermal conductive encapsulating insulation materials to improve the heat dissipation of electronic devices. Herein, we propose to modify the commercialized encapsulating materials of epoxy resin (EP) by incorporating three-dimensional hydroxylated boron nitride nanosheets (3D-BNNSs). The cryogel and vacuum freeze-drying techniques are employed to prepare the 3D-BNNSs using agarose. The results show that the constructed high thermal conductive structure of 3D-BNNSs can effectively enhance the thermal conductivity of EP and reduce the interfacial thermal resistance between BNNSs fillers. The thermal conductivity of 3D-BNNSs/EP composites with 33.03 wt% BNNSs reach 2.54 W/(m·K), which is 13.11 times higher than that of EP (0.18 W/(m·K)). Meanwhile, the resultant composites remain outstanding electrical insulation and dielectric properties. Because agarose contains numerous hydroxyl groups that can form hydrogen bonds with the hydroxyl groups on the surface-functionalized BNNSs, hydrogen bonding can lead to strong intermolecular interactions, which is conductive to accelarate phonon transport. Additionally, agarose can cross-link with the molecular chains of epoxy, impeding the movement of molecular chain segments and resulting in composites with low dielectric loss at high frequencies. This study demonstrates that the 3D-BNNSs/EP composites have great potential for application in thermal management of electronic components.

Computational investigation of methanol-based hybrid nanofluid flow over a stretching cylinder with Cattaneo–Christov heat flux

Abstract This study investigates heat transfer rates in (AA7075-AA7072/Methanol) hybrid nanofluid flows, considering non-uniform heat sources and Cattaneo–Christov heat flux, with significant implications for aerospace engineering by enhancing thermal management in aircraft engines. The findings could revolutionize automotive cooling system efficiency, optimize heat dissipation in electronic devices, and advance the design of renewable energy systems such as concentrated solar power plants. The study aims to conduct a comparative analysis of (AA7075/Methanol) nanofluid and (AA7075-AA7072/Methanol) hybrid nanofluid flow, examining heat transfer rates, non-uniform heat sources, and Cattaneo–Christov heat flux theory around a stretching cylinder. Thermal radiation and the Biot number are also evaluated. Two different nanoparticles, AA7072 and AA7075, are used with methanol to create AA7075/Methanol nanofluid and AA7075-AA7072/Methanol hybrid nanofluid. The study compresses the resultant non-linear partial differential equation system and applies suitable similarity transformations to reduce the governing partial differential equations with boundary conditions to dimensionless form. The BVP4C shooting method in MATLAB is employed to numerically and graphically solve these dimensionless ordinary differential equations. The results indicate that higher curvature parameter values correlate with increased velocity and temperature distribution profiles. A rise in nanoparticle volume fraction reduces the radial velocity profile but increases the temperature profile. Temperature distribution profiles increase with higher thermal radiation parameter and Biot number values, while higher thermal relaxation parameter values decrease temperature. Additionally, thermal distribution profiles rise with increasing values of both the time-dependent heat source constant and space-dependent heat source parameter.

Compliant composite elastomers via grafting short dangling chains for promoting thermal transport performance

AbstractThe multifunctional composite elastomers serve as thermal interface materials for heat dissipation in electronic devices when their thermal transport performance is enhanced. The common method for enhancement, continuously raising the thermal conductive filler loading only can improve thermal conductivity of composite elastomers but reduces compliance, resulting in elevated contact thermal resistance with solid surfaces, compromising thermal transport. To address this, we propose grafting short dangling chains onto the composite elastomer matrix to further promote compliance under a certain filler loading. Characterization results demonstrate that the grafted chains effectively reduce relaxation time, enabling faster deformation for the material under pressure. This approach enhances interfacial compatibility, widening the thermal transport path at contact interfaces to contact thermal resistance by 94% (from 17.8 to 1.07 mm2W/K), significantly improving overall thermal transport. Additionally, we discussed the feasibility of employing composite elastomers as thermal interface materials for efficient chip heat dissipation.Highlight The grafted dangling chains can promote the composite elastomers softness. The softness promotion can help reduce thermal contact resistance. A series of theories are employed to learn the mechanisms of the promotion. The resulting composite elastomers can be used as thermal interface materials.

Enhanced thermal energy storage of polyethylene glycol composite with high thermal conductive reaction-bonded BN aerogel

Organic solid-liquid phase change materials (PCMs) achieve thermal energy storage through solid-liquid phase change and are widely used for heat dissipation in electronic devices. However, organic solid-liquid PCMs have low thermal conductivity and leakage issues during phase transition. Therefore, BN aerogels were made through supramolecular self-assembly, freeze-drying, and heat treatment. By adjusting the proportion of raw materials and heating rate, thermal conductive BN aerogel with reaction-bonded fibers was obtained, which can stabilize the shape and enhance the thermal conductivity of polyethylene glycol (PEG) through the thermal conductive 3D framework. The BN/PEG PCMs showed excellent phase change enthalpy of 183.07 g J−1 (retained 97 % of PEG), superb shape stability, and high thermal conductivity of 0.89 W m−1 K−1 at 2.8 vol% BN content. The BN/PEG PCMs have enhanced thermal energy storage ability for heat dissipation, especially in the electronic field that requires electrical insulation.

The copper matrix composite with "sandwich" structure and three-dimensional networks, showcasing significantly improved thermal conducting performance

Copper matrix composites can be used to address the issue of heat dissipation in electronic devices. Nevertheless, the thermal conductivity (TC) of carbon fiber (CF)/copper (Cu) composites falls significantly below expectations. This is primarily attributed to the challenge of achieving a well-ordered arrangement of CF within the matrix, coupled with the issue of low interfacial bonding strength. A highly effective and uncomplicated approach to fabricate copper matrix composites featuring a "sandwich structure" of Cu-CF-Cu is introduced in this paper. This configuration, achieved through structural design facilitated by hot-press sintering and vacuum suction filtration, exhibited a three-dimensional graphene-like networks (3D-GLNs) and meticulously ordered CF layers over long distances. More importantly, in comparison to pure copper (350 W m−1 K−1), the laminated composite with 40 vol% CF of the CF layer had an in-plane TC of 510 W m−1 K−1, which was approximately 1.5 times greater than that of pure copper. Additionally, the coefficient of thermal expansion (CTE) of the laminated composite with 45 vol% was 9.98 ppm/K. The in-plane TC of the composite was comparable to that of the graphene/Cu composites with the same content. This underscores the advantages of the structural design, even in cases where the TC of the reinforced phase differs by a factor of two. The aforementioned findings demonstrate that this methodology for developing a unique "sandwich" structure can effectively enhance in-plane TC in CF/metal composites, presenting potential for utilization in electronic packaging requiring efficient directional heat transfer.

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.

Bubble Interaction and Heat Transfer Characteristics of Microchannel Flow Boiling With Single and Multiple Cavities

Abstract Flow boiling in microchannels can effectively address the challenges of high power density heat dissipation in electronic devices. However, the intricate bubble dynamics during the two-phase flow in microchannel necessitates understanding the characteristics of complex bubble hydrodynamics. In this study, we perform 2D numerical simulations of flow boiling using the Cahn-Hilliard phase-field method for a 200-µm width microchannel with single and multiple cavities in COMSOL Multiphysics (V5.3). The numerical model successfully captures bubble dynamics, encompassing vapor embryo generation, bubble growth, departure, coalescence, sliding, and stable vapor plug formation. The heat transfer mechanism inside the microchannel is dominated by bubble nucleation and thin-film evaporation. Elevated wall superheats in a single nucleation cavity, and increased mass flux facilitates higher bubble departure frequency and heat transfer performance. Temporal pressure fluctuations are observed inside microchannels in multiple cavities due to bubble coalescence, departure, and subsequent nucleation. Increasing the nucleating cavities from 2 to 5 within the microchannel while maintaining consistent cavity spacing of 100 µm has resulted in nearly 32% enhancement in heat transfer performance. This study offers valuable findings that can help improve the thermal management of electronic devices.

Phase change composites with ultra-high through-plane thermal conductivity achieved by vertically-aligned graphite film and double-shelled microcapsules

The heat dissipation in electronic devices has become bottleneck problem. One of the best solutions is to develop high performance materials which can not only dissipate the heat away, but also absorb heat energy. This kind of double function materials can be obtained by simultaneously using high thermal conductivity (TC) materials and phase change materials. The formation of continuous network of thermally conductive fillers is demonstrated as one of the most effective methods for fabricating highly thermally conductive composites. Here, graphite films (GF) are stacked and vertically cut to endow the composites with high through-plane TC. The obtained composites exhibit a through-plane TC of 51.55 W m−1 K−1 and a low thermal resistance of 0.398 °C cm2 W−1. Besides, double-shelled PDA@SiO2@paraffin (Pa) microcapsules are embedded into the composite to give its good heat-absorption capacity. Via a CPU thermal stress test, the composites demonstrate satisfactory temperature controlling performance.

High thermally conductive and electrical insulating “Sandwich” structured composites fabricated by hot-pressing of PEEK film combined with fBNNSs@fMWCNT/SPEEK membrane via electrospinning

With the rapid development of 5 G technology, the heat dissipation of electronic devices has become an important challenge. It is particularly essential to construct efficient thermal transfer networks in order to obtain advanced materials with superior thermal conductivity as well as excellent electrical insulating properties. In this work, poly (ether ether ketone) (PEEK) was sulfonated to achieve its solubility for electrospinning. Multi-scale hybrid fillers containing hydroxylated boron nitride nanosheets (fBNNSs) and carboxylated multi-walled carbon nanotubes (fMWCNT) are aligned along the direction of sulfonated PEEK (SPEEK) fibers during electrospinning process where fMWCNT with high aspect ratio can be used as mediators to connect the dispersed fBNNSs resulting in synergistic effect to extensively improve the thermally conductive performance. The hydrogen bond interaction among sulfonic acid group, carboxy groups and hydroxy groups from the matrix and modified fillers can not only make the fillers disperse uniformly but also improve the interfacial properties, thus reducing the phonon scattering at the interface efficiently, to enhance the thermal conductivity significantly at relatively low filler loading. fBNNSs@fMWCNT/SPEEK composite exhibits excellent thermal conductivity (λ) of 5.25 W/(m·K) when the filler content reached by 26 wt% with the ratio of fBNNSs to fMWCNT of 25:1(wt:wt). Under the composition above, the excellent electrical insulating property (2.54×1015Ω·cm) is achieved as well. Furthermore, fBNNSs@fMWCNT/SPEEK fiber membrane can be used as thermally conductive filler to construct a "sandwich" structured composite with PEEK film. When the mass ratio is 1:1, the λ of composite is 3.1 W/(m·K), which is 1200% higher than that of PEEK. This work provides better understanding of PEEK based thermal conductive composites for the prospective application of thermal management materials in electrical insulating related fields.

Characterization of a Novel Cost-efficient and Environmentally Friendly Graphene-enhanced Thermal Interface Material

With the continuous development of electronic devices, effective heat dissipation has become a major factor affecting service life. Thermal interface materials (TIM) play a key role in controlling heat dissipation of electronic devices and have thus attracted widespread attention. In this study, we used graphene flakes (GF) derived from graphene film that is wasted during the preparation of commercial large-scale graphene-enhanced TIMs as thermally conductive fillers to formulate a new TIM. The thermal conductivity of the developed TIM is 50% higher with GFs than without. Furthermore, the TIM has a tensile strength of 0.46 MPa with an elongation at break of 1225%, a maximum compression strength of 0.64 MPa at 50% compression, and high mechanical cycle stability. This report provides a cost-efficient and environmentally friendly approach to producing high-performance TIMs for electronic cooling applications.

Shape-stabilized phase change materials for thermal energy storage and heat dissipation

Shape-stabilized phase change material (SSPCM) are widely used as energy storage materials due to its advantages of easy preparation and adjustable scale. But the thermal conductivity enhancement of SSPCM still need to be further studied to improve the energy storage efficiency. In this work, silicone rubber (SR)/paraffin@SiO2 (Pn@SiO2)/graphene nanoplates (GNPs) shape-stabilized phase change materials (SPG) with different GNPs content were prepared. Pn@SiO2 and GNPs can be homogeneously dispersed in the SR matrix due to the enhanced interfacial compatibility between Pn@SiO2 and SR. The leakage rate of SPG composites was as low as 0.25% due to the protection of SiO2 shell, SR matrix and GNPs. The SPG composites had excellent thermal storage properties, with the enthalpy about 50 J·g−1. The thermal conductivity of SPG composites was improved with the content of GNPs, the thermal conductivity of SPG reach 0.989 W·m−1·K−1 at a GNPs content of 10 phr. The low hardness of SPG composites above the phase change temperature can provide a more cohesive surface when applied to heat dissipation. The heat dissipation of the SPG composites in electric devices was simulated and demonstrated that the addition of GNPs made the heat dissipation rate of the SPG composites increased significantly. Therefore, the SPG composites can be applied in thermal energy storage and heat dissipation of electronic devices.

Magnetic field effect on mixed convection flow inside an oval-shaped annulus enclosure filled by a non-Newtonian nanofluid

The phenomenon of flow around a static or rotating circular cylinder has significant applications in various engineering fields, such as building, bridge, and structure engineering. It can be used to control flow-induced vibration, blowing or suction, moving surfaces, acoustic thriller, and synthetic jet. Additionally, there is a need to enhance heat transfer rates in many life and industrial applications, including cavity shape enhancement, heating or cooling spread inside a cavity, heat dissipation in electronic devices, thermal mixing in storage units, solar collectors, desalination, and journal bearing lubrication. This study explores the effect of a horizontal magnetic field and a rotating inner circular cylinder on mixed convection within a two-dimensional oval-shaped enclosure filled with a non-Newtonian nanofluid. The Galerkin Finite Element Method (GFEM) is utilized for analysis, with the enclosure undergoing differential heating and cooling on the inner cylinder wall and the enclosure wall, respectively. The nanofluid consists of water infused with copper nanoparticles. The study explores various simulation parameters, including the Richardson number (Ri), Hartmann number (Ha), the inclination angle of the enclosure (β), power-law index (n), circle center eccentricity (e), and nanoparticles volume fraction (φ). It has been observed that as the Ha and n index increase for different Ri values, a wavy trend in local Nusselt number (Nu) profiles along the heat source surface is observed. Additionally, the heat transfer rate decreases with increasing Ri for various combinations of Ha and n index. Under specific conditions, such as Ri = 0.001, Ha = 60, e = 0, φ = 0.09, and β = 90, the results show that, compared to a Newtonian fluid (n = 1), the heat transfer rate exhibits percentage gains of approximately 6.31% for a pseudo-plastic fluid (n = 0.6) and 8.47% for a Dilatant fluid (n = 1.4). The convective heat transfer was significantly enhanced when the eccentricity of the cylinder was positioned in the lower or upper regions of the oval-shaped enclosure, particularly at e = - 0.3. The highest heat transfer rates were observed at β = 60 and 240.

Improvement of interfacial thermal resistance between TIMs and copper for better thermal management

Due to the increasing power consumption of modern electronic devices and rapid rise in heat generation, how to efficiently manage the heat dissipation becomes a challenge. The previous studies have shown the importance of interface treatment for better thermal management while the mechanism is lacking yet. Here, we study the interface thermal transport between the thermal interface materials (TIMs) and the copper substrate using both experimental measurements and theoretical calculations. The results show that after interface treatment, the thermal contact resistance between the graphite materials and copper decreases from 87.96 K · mm2 · W−1 to 20.26 K · mm2 · W−1. For the practical testing, a difference up to 7 ○C is demonstrated between the treated and untreated samples, indicating the potential of reduction of thermal contact resistance for the heat dissipation in electronic devices, which is verified in our theoretical calculation as well. Our study provides an applicable approach to enhancing the thermal stability in electronic devices by investigating the impact of the interfacial thermal resistance on heat dissipation.

Exploring Thermal Characteristics of Functionally Graded Nanomaterials for Enhanced Heat Dissipation in Electronic Devices

Exploring Thermal Characteristics of Functionally Graded Nanomaterials for Enhanced Heat Dissipation in Electronic Devices

Facile constructing Ti3C2Tx/TiO2@C heterostructures for excellent microwave absorption properties

Optimizing and enhancing the performance of electromagnetic wave (EMW) absorption materials relies on the modification of their composition and structure through heterogeneous interface engineering. Ti3C2Tx’s high conductivity results in an impedance mismatch, which hinders efficient EMW absorption. Herein, a one–step catalytic chemical vapor deposition (CCVD) method is used to construct the Ti3C2Tx/TiO2@C heterogeneous structure. Upon annealing at 500 °C, amorphous carbon is uniformly deposited on the Ti3C2Tx surface, thereby incorporating the scale–like TiO2 generated during the process. The inclusion of the amorphous carbon layer and TiO2 reduces the substrate’s conductivity, achieving optimized impedance matching. Additionally, building heterogeneous interfaces between Ti3C2Tx, TiO2, and C enriches multiple loss mechanisms involving dipole and interfacial polarization, ultimately enabling optimal EMW absorption performance. The minimum reflection loss (RLmin) value of Ti3C2Tx/TiO2@C–500 is –53.12 dB when its thickness and frequency are 1.15 mm and 13.80 GHz, respectively. Moreover, thermal infrared imaging confirms that coatings fabricated using Ti3C2Tx/TiO2@C–500 demonstrate a favorable heat dissipation rate, validating its effectiveness in addressing the challenge of efficient heat dissipation in electronic devices. This study significantly contributes to the progress of two–dimensional (2D) materials, enabling high–performance EMW absorption and expanding their applications in complex scenarios.

Improved thermal conductivity of epoxy composites filled with three-dimensional boron nitride ceramics-carbon hybrids

Epoxy (EP) is the preferred packaging materials used as a crucial component in power semiconductor devices. However, its low thermal conductivity (TC) always has negative impact in the heat dissipation of electronic devices. In this paper, we use hole-making method to prepare three-dimensional boron nitride ceramics-carbon (3D-BN-C) hybrids which are filled in EP matrix to improve the TC of the 3D-BN-C/EP composites. The results show that TC values of 3D-BN-C/EP composites are much superior to the BN/EP composite with random distribution of BN and 3D-BN/EP composite without carbon. The improved TC is mainly attributed to the high TC-3D skeleton structure and the low interface thermal resistance (R) due to the carbon connected with BN fillers. Infrared thermal images and Comsol simulation demonstrate that high TC 3D-BN-C/EP composite offers excellent heat dissipation capability of EP composites used as packing insulation materials. In addition, the dielectric loss of 3D-BN-C/EP composite still remains at a relative low level in a wide frequency range, exhibiting good insulation property and great potential to be used as high-performance packing insulation materials in electronic device applications.