Formation of Sn-multiwalled carbon nanotube composite layer for the application of thermal interface materials

Fabrication of Sn-MWCNT composite layer through reflow of Sn-decorated MWCNT powder was conducted in this study. Commercially available MWCNTs were oxidized by using K2Cr2O7 / H2SO4 solution for the surface modification. The oxidized MWCNTs were dispersed in SnCl2 / HCl solution and subsequently a reducing agent NaBH4 was introduced to form crystalline Sri. During the Sn reduction process, 1,10-phenanthroline capping agent was introduced to control the particle shape and size. It was found that SnO2 nanoparticles on the surface of MWCNTs an crystalline Sri particles were obtained simultaneously through the chemical reduction reaction. When 1,10-phenanthroline was used, Sn particles had spherical shape and uniform size compared to the one without 1,10-phenanthroline. Afterwards, the Sn-MWCNT powders were mixed with a flux to form a paste for a wetting test on a Cu substrate. After a reflow step of the paste, Sn-MWCNT composite layer could be formed showing no separation between MWCNTs and Sri by bonding of molten Sri to SnO2 nanoparticles on the surface of MWCNTs.