This work presents a novel fabrication approach of multiwalled carbon nanotubes (MWNTs) reinforced copper (Cu) matrix nanocomposites. A combination of nanoscale dispersion of functionalized MWNTs in low viscose media of dissolved paraffin wax under sonication treatment followed by metal injection molding (MIM) technique was adopted. MWNTs contents were varied from 0 to 10？vol.%. Information about the degree of purification and functionalization processes, evidences on the existence of the functional groups, effect of sonication time on the treated MWNTs, and microstructural analysis of the fabricated Cu/MWNTs nanocomposites were determined using TEM, EDX, FESEM, and Raman spectroscopy analysis. The results showed that the impurities of the pristine MWNTs such as Fe, Ni catalyst, and the amorphous carbon have been significantly removed after purification process. Meanwhile, FESEM and TEM observations showed high stability of MWNTs at elevated temperatures and uniform dispersion of MWNTs in Cu matrix at different volume fractions and sintering temperatures (950, 1000 & 1050°C). The experimentally measured thermal conductivities of Cu/MWNTs nanocomposites showed remarkable increase (11.25% higher than sintered pure Cu) with addition of 1？vol.% MWNTs, and slight decrease below the value of sintered Cu at 5 and 10？vol.% MWNTs. 1. Introduction With continued demand for high-performance electronic devices with low cost, small size and more efficient electronic systems, thermal challenges became a serious concern in electronic packaging design [1]. More transistors means more heat is generated within these systems. High-operating temperature decreases the overall reliability or even permanently damages the entire electronic system [2]. Therefore, a new thermal management solution is required to provide cost-effective means of dissipating heat from next generation microelectronic devices [3]. In response to these critical needs, high-performance heat sink nanocomposite made of copper reinforced by multiwalled carbon nanotubes is proposed. The superior physical, mechanical, and thermal properties of MWNTs have led it to have very high impact on developing new generations of nanocomposite materials with enhanced functionality and wide range of applications [4]. However, incorporation of MWNTs in metal matrix has its own barriers and difficulties that might destroy the desired properties of MWNTs [5]. Meanwhile, dispersion of MWNTs in metal matrix nanocomposites is known as the most difficult challenge in fabricating MWNTs based metal matrix nanocomposite. This can
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