Thermal Conductivity of Polymer-Based Composites: Fundamentals and Applications

The continuing miniaturization of electronic devices and the increasing power output of electrical equipment have created new challenges in packaging and insulating materials. The key goals are to develop materials with high thermal conductivity, low coefficient of thermal expansion (CTE), low dielectric con stant, high electrical resistivity, high breakdown strength, and most importantly, low cost. Polymeric materials have attracted increasing interest because of their excellent processability and low cost; however, most polymers are thermally insulating and have a thermal conductivity between 0.1 and 0.5 W-m-ι-K"1. One approach to increase the thermal conductivity of a polymer is to introduce high-thermal-conductivity fillers, such as aluminum oxide, aluminum nitride, boron nitride, silicon nitride, beryllium oxide, or diamond. In this review paper, we explore how dielectric polymer composites with high thermal conductivity have been developed.

A review of dielectric polymer composites with high thermal conductivity

Dielectric polymer composites with high thermal conductivity are very promising for microelectronic packaging and thermal management application in new energy systems such as solar cells and light emitting diodes (LEDs). However, a well-known paradox is that conventional composites with high thermal conductivity usually suffer from the high dielectric constant and high dielectric loss, while on the other hand, composite materials with excellent dielectric properties usually possess low thermal conductivity. In this work, an ideal dielectric thermally conductive epoxy nanocomposite is successfully fabricated using polyhedral oligosilsesquioxane (POSS) functionalized boron nitride nanotubes (BNNTs) as fillers. The nanocomposites with 30 wt% fraction of POSS modified BNNTs exhibit much lower dielectric constant, dielectric loss tangent, and coefficient of thermal expansion in comparison with the pure epoxy resin. As an example, below 100 Hz, the dielectric loss of the nanocomposites with 20 and 30 wt% BNNTs is reduced by one order of magnitude in comparison with the pure epoxy resin. Moreover, the nanocomposites show a dramatic thermal conductivity enhancement of 1360% in comparison with the pristine epoxy resin at a BNNT loading fraction of 30 wt%. The merits of the designed composites are suggested to originate from the excellent intrinsic properties of embedded BNNTs, effective surface modification by POSS molecules, and carefully developed composite preparation methods.

Polyhedral Oligosilsesquioxane‐Modified Boron Nitride Nanotube Based Epoxy Nanocomposites: An Ideal Dielectric Material with High Thermal Conductivity

Thermal transport in polymeric materials and across composite interfaces

Improved thermal conductivity of epoxy composites using a hybrid multi-walled carbon nanotube/micro-SiC filler

Study of the thermal conduction mechanism of nano-SiC/ DGEBA/EMI-2,4 composites

This report covers the results of a study on evaluating the effect of nano-SiC particles on mechanical, thermal and electrical properties of epoxy by lap shear, TGA, DSC and electrical tests. Epoxy composites filled with micro-SiC particles were also studied for comparison. The mechanisms of performance improvement were discussed in detail. The results showed that with identical loading, silane treated nano-SiC filled nanocomposites have the best properties. The volume resistivity decrease, dielectric constant e increase and loss tangent tan(δ) increase by addition of silane treated nano-SiC particles are smaller than those by the other fillers. Silane treatment of nanoparticles improves each performance, including increases shear strength, thermal stability, volume resistivity and decreases e and (δ). The addition of nano-SiC particles remarkably improves shear strength, e and tan(δ), while slightly enhances thermal stability of epoxy. 8 vol. % silane treated nano-SiC/epoxy composite has the highest shear strength 10.6 MPa with the maximum enhancement, 80%, over the neat resin. It also has good temperature independence of dielectric properties and enough volume resistivity, which meet the demand of some microelectronics materials.

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Xin Wang

Papers

Study of the thermal conduction mechanism of nano-SiC/ DGEBA/EMI-2,4 composites

Study on Mechanical, Thermal and Electrical Characterizations of Nano-SiC/Epoxy Composites