High-performance Thermal Management Materials Research Articles

Electrically insulating, layer structured SiR/GNPs/BN thermal management materials with enhanced thermal conductivity and breakdown voltage

Layer structured high-performance thermal management materials via integrating the advantages of boron nitride (BN, electrically insulating) and graphene nanoplatelets (GNPs, highly thermally conductive) as fillers were realized by a facile and scalable strategy. Outstanding thermal conductivity (TC) of 8.45 W m−1 K−1, the highest value among reported electrically insulating polymer-based materials, excellent electrical insulation (breakdown voltage∼5.33 kV/mm; volume resistance ∼1012Ωcm) and superior electromagnetic interface shielding performance are achieved at a filler loading of 17.88 vol%. Moreover, the mechanical properties and hardness are also in quite good range. Thus, a promising method is provided for large scale production of superior thermal management materials.

Coupled Chiral Structure in Graphene-Based Film for Ultrahigh Thermal Conductivity in Both In-Plane and Through-Plane Directions.

The development of high-performance thermal management materials to dissipate excessive heat both in plane and through plane is of special interest to maintain efficient operation and prolong the life of electronic devices. Herein, we designed and constructed a graphene-based composite film, which contains chiral liquid crystals (cellulose nanocrystals, CNCs) inside graphene oxide (GO). The composite film was prepared by annealing and compacting of self-assembled GO-CNC, which contains chiral smectic liquid crystal structures. The helical arranged nanorods of carbonized CNC act as in-plane connections, which bridge neighboring graphene sheets. More interestingly, the chiral structures also act as through-plane connections, which bridge the upper and lower graphene layers. As a result, the graphene-based composite film shows extraordinary thermal conductivity, in both in-plane (1820.4 W m-1 K-1) and through-plane (4.596 W m-1 K-1) directions. As a thermal management material, the heat dissipation and transportation behaviors of the composite film were investigated using a self-heating system and the results showed that the real-time temperature of the heater covered with the film was 44.5 °C lower than a naked heater. The prepared film shows a much higher efficiency of heat transportation than the commonly used thermal conductive Cu foil. Additionally, this graphene-based composite film exhibits excellent mechanical strength of 31.6 MPa and an electrical conductivity of 667.4 S cm-1. The strategy reported here may open a new avenue to the development of high-performance thermal management films.

Grafting rubber chains onto boron nitride nanosheets for highly flexible, thermally conductive composites

An ultra-flexible, thermally conductive and electrically insulating composite paper based on BNNSs was fabricated by vacuum filtration. The paper was prepared via a facile two-step coating/grafting modification process. The surface of BNNSs was firstly wrapped by polyrhodanine and subsequently rubber chains were mechanochemically grafted onto the polyrhodanine coating. In addition, by controlling the content of grafted rubber chains, a flexible and electrically insulating composite paper with an in-plane thermal conductivity of up to 45.7 Wm−1K−1 has been achieved. This paper may have potential applications as high performance thermal-management materials in electronics.

Highly in-Plane Thermally Conductive Composite Films from Hexagonal Boron Nitride Microplatelets Assembled with Graphene Oxide

With the development of portable and flexible devices, demands for high-performance thermal management materials with high in-plane thermal conductivity (TC), mechanical flexibility, and electrical insulation are growing. Hexagonal boron nitride (BN) is a promising thermally conductive filler due to its high in-plane TC and electrical insulation. In this work, taking full advantage of good film-forming feature of graphene oxide (GO) suspension and its ability to stably disperse BN microplatelets (BNMPs) in the aqueous medium, the GO/BNMPs composite films with high in-plane TCs were prepared by a simple cast-drying method. The structure characterization demonstrated that GO can induce BNMPs to preferably arrange in-plane orientation in the composite films. The resultant composite films possessed a maximum in-plane TC value of 10.3 W/m·K at 50 wt % BNMPs. Moreover, the films exhibited excellent mechanical flexibility and satisfactory electrical insulation. The proposed method of fabricating BNMPs-based comp...

Silver/Diamond Composite Material - Powder Metallurgical Route and Thermo-Physical Properties

To meet the need of high-performance thermal management materials in the field of electronic applications, heat sink materials reinforced with synthetic diamonds have been prepared via powder metallurgy. A matrix of a silver alloy with a silicon content of 0.45 wt.% was chosen out of the prediction of the thickness of a final carbide layer of about 180 nm. The volume content of the diamonds and the diamond size were kept constant. The mixed powders were consolidated by Spark Plasma Sintering (SPS) using different sintering temperatures between 800 and 870 °C with a holding time of 30 min. The maximum thermal conductivity of 680 W/(mK) measured at room temperature and 620 W/(mK) at 275 °C was obtained at 810 °C sintering temperature. The degradation of the most promising sample after one thermal cycle up to 275 °C was determined below 1 percent of the value after sintering.

Interfacial Engineering of Silicon Carbide Nanowire/Cellulose Microcrystal Paper toward High Thermal Conductivity.

Polymer composites with high thermal conductivity have attracted much attention, along with the rapid development of electronic devices toward higher speed and better performance. However, high interfacial thermal resistance between fillers and matrix or between fillers and fillers has been one of the primary bottlenecks for the effective thermal conduction in polymer composites. Herein, we report on engineering interfacial structure of silicon carbide nanowire/cellulose microcrystal paper by generating silver nanostructures. We show that silver nanoparticle-deposited silicon carbide nanowires as fillers can effectively enhance the thermal conductivity of the matrix. The in-plane thermal conductivity of the resultant composite paper reaches as high as 34.0 W/m K, which is one order magnitude higher than that of conventional polymer composites. Fitting the measured thermal conductivity with theoretical models qualitatively demonstrates that silver nanoparticles bring the lower interfacial thermal resistances both at silicon carbide nanowire/cellulose microcrystal and silicon carbide nanowire/silicon carbide nanowire interfaces. This interfacial engineering approach provides a powerful tool for sophisticated fabrication of high-performance thermal-management materials.

ダイヤモンド粒子分散型金属基複合材料の開発動向

In order to fabricate high-performance thermal management materials with ultra-high thermal conductivities and low CTEs, we have recently initiated a series of investigations, where metal-matrix composites (MMCs) containing high thermal conductive fillers were uniquely fabricated. In our study, to avoid the damage of filler particle surfaces, spark plasma sintering (SPS) processing was used as a processing technique. In the present review, thermal properties of diamond particle dispersed MMCs fabricated using SPS process in our recent works are introduced in comparison with those produced using various fabrication techniques by other researchers.

金属系放熱材料の開発の現状

High-performance thermal management materials should have high thermal conductivities and low coefficients of thermal expansion (CTE) for maximizing heat dissipation and minimizing thermal stress and warping, which are critical issues in packaging of power semiconductors, light-emitting diodes and micro electro mechanical systems. Thermal stress and warping arise from CTE differences, which become significant in advanced electronic devices because of high heat generated, for example, when high-power laser diodes or high integration level of IC are in use. To ensure ideal or desired performance and adequate life of these electronic devices, it is necessary to decrease the junction temperature between two components to temperatures lower than: 398 K for military and automobile logic devices; and 343 K for some commercial logic devices. In the case of high-power density devices, the allowable temperature range is limited in the package base and die-attach thermal resistances. In any cases, the development of thermal management materials is significant in electronics fields.In order to fabricate high-performance thermal management materials with ultra-high thermal conductivities and low CTEs, we have recently initiated a series of investigations, where metal-matrix composites (MMCs) containing high thermal conductive fillers were uniquely fabricated. In our study, to avoid the damage of filler particle surfaces, spark plasma sintering (SPS) processing was used as a processing technique. In the present review, thermal properties of particle dispersed MMCs fabricated using SPS process in our recent works are introduced in comparison with those produced using various fabrication techniques by other researchers.