Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

3
Physical Properties of Carbon Nanotube–Metal
Nanocomposites
3.1
Background
In recent decades there has been a major advance in the development of metal-matrix
microcomposites reinforced with carbonaceous fillers. Carbon fibers have many
excellent thermal and mechanical properties which make them attractive components
of strong, light-weight composites. Conventional PAN-based fibers with high
tensile strength and low modulus find applications as reinforcement materials for
structural composites. Pitch-based carbon fibers with lower tensile strength, high
modulus, excellent thermal and electrical conductivity are ideal reinforcements for
composite applications in which heat dissipation is crucial [1, 2]. Such materials can
be used to design a thermal doubler for satellite radiator panels [3]. However, carbon
fibers are chemically reactive with metals during the composite fabrication, particularly
using the liquid metal process. Chemical reactions between carbon fiber and
metal during composite processing would degrade the matrix/interface properties.
Therefore, efforts have been made to improve the performances of metal-matrix
composites (MMCs) by proper control of the interfacial characteristics [4].
Recently, thermal management within the overall design of electronic products is
increasingly important with the increase of package density in semiconductor
devices. The increasing heat flux densities from dense packaging and ineffective
dissipation of the thermal energy can lead to premature failure of electronic devices.
Therefore, thermal management in electronic devices becomes increasingly
important for reliable and long life performances [5]. Heat dissipation is usually
achieved by the use of heat sinks, heat spreaders and packaging materials. Many
composite materials have been developed to transport heat within electronic
devices and dissipate it into the ambient environment more efficiently [6]. These
include MMCs reinforced with pitch-based carbon fibers and SiC particles. Table 3.1
lists typical physical properties of some commercially available Al-based composites
used in electronic devices. For the purposes of comparison, the properties of
pure Al, Cu and Si are also listed [7, 8]. In Table 3.1, AlSiC composite materials are
commercial products of CPS Technologies Corporation in which aluminum alloy
(A356) is reinforced with different volume contents of SiC particles. They are
available at low cost with near net shape fabrication versatility. Their thermal
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