Abstract
Thermal interface materials with high thermal conductivity and low hardness are crucial to the heat dissipation of high-power electronics. In this study, a high magnetic field was used to align the milled carbon fibers (CFs, 150 μm) in silicone rubber matrix to fabricate thermal interface materials with an ordered and discontinuous structure. The relationship among the magnetic field density, the alignment degree of CFs, and the properties of the resulting composites was explored by experimental study and theoretical analysis. The results showed higher alignment degree and enhanced thermal conductivity of composites under increased magnetic flux density within a certain curing time. When the magnetic flux density increased to 9 T, the CFs showed perfect alignment and the composite showed a high thermal conductivity of 11.76 W/(m·K) with only 20 vol% CF loading, owing to the ordered structure. Meanwhile, due to the low filler loading and discontinuous structure, a low hardness of 60~70 (shore 00) was also realized. Their thermal management performance was further confirmed in a test system, revealing promising applications for magnetic aligned CF–rubber composites in thermal interface materials.
Highlights
As a common type of thermal management material, thermal interface material (TIM)has been extensively applied in electronic packaging to fill the gap between the contact interface of heat sources and heat sinks, which constitutes a dominant factor in achieving efficient thermal transfer
Besides high intrinsic thermal conductivity, low hardness is crucial to achieving high performance in TIMs, which means that the TIMs should be able to deform to conform to the topography of the mating surface so as to improve interfacial heat transfer, and is especially vital when working with irregular surfaces [1,2,3]
There is no denying that the thermal conductivity of composites can be improved by increasing filler content [4], but this comes at the expense of increased hardness [5]
Summary
As a common type of thermal management material, thermal interface material (TIM). has been extensively applied in electronic packaging to fill the gap between the contact interface of heat sources and heat sinks, which constitutes a dominant factor in achieving efficient thermal transfer. It is generally accepted that filler alignment is an effective approach to remarkably improve the thermal conductivity of composites in a specific direction [4,6], which is useful and well suited to the requirements of TIMs. The control over filler alignment has been used to make the most of the advantages of the anisotropic properties of low-dimensional materials. The high magnetic flux density generated by the superconducting magnet can control feebly magnetic fillers without the help of other mediums It is an appealing method, there are relatively few studies devoted to aligning high-thermal-conductivity CF directly using a high magnetic field, and experimental studies of the impacts of magnetic flux density on microstructure and properties of CF reinforced composites are even fewer. The composites with magnetic alignment showed outstanding thermal management performance when they were used as TIMs
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