An Assessment of Copper Electrodeposition into Bakky-Pepar Consisted of Single-Walled Carbon Nanotube

Abstract

Introduction Copper has many useful properties, such as high electrical conductivity, good thermal conductivity and ductility, resulting in the widespread use of copper plating in an electronics industry. Single-walled carbon nanotubes (SWCNTs) also exhibit attractive characteristics, including stable electrical resistance in the presence of high currents, superior thermal conductivity and good field emission properties, and so have a wide range of applications. Cu/SWCNT composites are also expected to exhibit excellent electrical and thermal conductivities. In the present research, we attempted to fabricate a novel Cu/SWCNT composite by copper deposition into Bakky-paper consisted of SWCNTs. Experimental Bakky-paper (SWCNT sheet) with a thickness in the range of 30 to 40 mm (Zeon Co.) was used as the cathode, and copper electrodeposition was performed on both sides under galvanostatic conditions with an immersed surface area of 2 cm2(= 1 cm × 1 cm × 2). Copper containing phosphorous as anodes were placed at both sides of the cathode, and then copper deposition was carried out with or without additives. The additives were polyethylene glycol (PEG), chloride ions, bis(3-sulfopropyl) disulfide (SPS) and Janus green B (JGB). The surfaces and cross-sectional morphologies of the composites obtained by the electrodeposition were observed by a field emission scanning electron microscopy (FE-SEM). The effects of plasma pretreatment of the Bakky-paper (SWCNT sheet) on microstructure and copper deposition were also examined. Results and Discussion Figure 1 compares cross-sectional SEM images of Cu/SWCNT composites prepared by two kinds of electrodeposition bath. Figure 1(a) displays the composite prepared in a bath without additives. It is clear that copper plating proceeded only on Bakky-paper surface. This is the reason why the plating liquid could not penetrate the sheet. In contrast, the use of various additives in the plating bath (100 ppm PEG + 50 ppm Cl- + 2 ppm SPS + 2 ppm JGB) resulted in copious copper deposition within the sheet structure (Figure 1(b)). Electrodeposition under these conditions also generated numerous voids in the Cu/SWCNT composite and greatly increased the thickness of the SWCNT sheet. The application of the Cu/SWCNT composite-film would be effective for the development of electronics devices. Figure 1