## 1 Introduction  
As the trend in power electronics systems moves toward smart and wearable electronics, effective use of thermal management materials is of critical importance due to the strong demand for the enhancement of power densities and miniaturization and weight reduction [1; 2; 3; 4; 5]. Of the various thermal management elements, copper (Cu) is among the most widely used materials for various kinds of passive heat exchangers including sinks, spreads, and pipes because of its excellent thermal conduction (\(\sim\)400 W/m\(\cdot\)K) and weldability with solders, thereby making it compatible with electronic applications [7]. However, since Cu has a relatively high density of 8.96 g/cm\({}^{3}\) compared to aluminum (2.70 g/cm\({}^{3}\)), its use can be restricted in applications such as the heat dissipation of electronics, automobile and aerospace electronics, of which space and weight is a strict requirement [3; 8; 9]. Therefore, fabricating and developing a new heat management materials system with lower density and good weldability still remains a big challenge in future electronic cooling. Recently, as a promising alternative, carbon allotropes such as diamond [10], natural graphite [11], synthetic graphite [12; 13], carbon nanotubes/fiber/flakes [14], and graphene [15; 16; 17; 18] have attracted great attention. However, when a polymeric thermal adhesive is applied for passively exchanging the heat at the interfacial region between the heat source and the carbon-based heat dissipater, undesired thermal stress and warpage in electronic components possibly takes place because of discrepancy in thermal expansion coefficients [3; 19; 20]. Another presumable issue in the solely used carbon-based materials is weak bonding with solders, thus leading to ascending thermal resistance [3; 19; 20]. To amend the aforementioned issues, effort to combine Cu with carbon-based materials have been made to enhance thermal management capability and concurrently reduce the density of Cu [21; 22]. Actually, recent studies have successfully shown a variety of routes to fabrication of Cu-matrix composites by incorporating the carbon allotropes into a Cu matrix such as hot pressing [22], vacuum pressure infiltration [21], electro- [3; 23; 24] and electroless plating [25], chemical vapor deposition [26], spark plasma sintering [27], etc. Unfortunately, most studies have focused on improvement of thermal conductivity, reduction of Cu density and the distribution of carbon-based reinforcements, rather than characterization of the interfacial region between the Cu matrix and the carbon allotropes as reinforcements.  
In the present study, we have demonstrated a facile and robust way for the fabrication of Cu-graphite composites (CGCs) with spatially-positioned graphite phases. The graphite layers bonded to the copper matrix and the resulting composite structure were entirely characterized. The preferential orientation and angular displacement of the nano-sized graphite fiber reinforcements in the copper matrix were clarified by polarized Raman scattering. Close investigation of the change of the Raman G-peak frequency with the laser excitation power provided us with a manifestation of the structural and electronic properties of the Cu-graphite composites (CGCs) with spatially-distributed graphite phases. Here, we compared the thermal characteristics of G-peak shifts and strengths due to thermal reduction at the copper, graphite, and graphene interfaces in the composites.