碳纳米管对微胶囊铜复合浆料导电性能的影响

Effect of carbon nanotubes on electrical conductivity of micro-encapsulated copper electron paste

为提高铜浆料的导电性能,利用微胶囊技术对铜粉表面做改性处理,添加碳纳米管为导电增强相,制备碳纳米管-微胶囊铜复合浆料。利用四探针测试仪、扫描电子显微镜(SEM)等研究了微胶囊铜粉的抗氧化性能及碳纳米管的参数、添加量对铜浆料导电性能的影响,分析其导电机理并建立导电相连接模型。研究结果表明:微胶囊化的铜粉具有较好的抗氧化性和导电性。当碳纳米管与铜粉的质量比为4∶96时,采用管径1~2 nm,长度5~30 nm的碳纳米管制备的复合浆料的电阻率达到最小值6.05 mΩ·cm,与纯铜浆料相比降低了89.39%。以碳纳米管-铜复合浆料与铜浆料分别制得导电膜,两者相比,前者更平坦、更致密,导电相间的接触更紧密,大量的碳纳米管覆盖在铜粉颗粒表面或填充铜粉颗粒间隙,同时碳纳米管之间相互"吸引",形成致密的网状结构,在铜粉颗粒之间建立起大量的导电"桥梁",从而改善了复合浆料的导电性能。

In order to improve the conductivity of copper paste, the surface of copper powder was modified by microcapsule technology, and carbon nanotubes were added as conductive reinforcement phase, carbon nanotubes-microencapsulated copper composite paste was prepared.The oxidation resistance of microencapsulated copper powder, and the effect of carbon nanotubes parameters and additions on the conductivity of copper paste were studied by four-probe tester and scanning electron microscopy(SEM). The electric conduction mechanism was analyzed and the conductive connection model was established. The results show that microencapsulated copper powder has excellent oxidation resistance and conductivity. When the mass ratio of carbon nanotubes to copper powders is 4∶96, the resistance of composite paste prepared by carbon nanotubes with 1~2 nm indiameter and 5~30 nm in length reaches a minimum value of 6.05 mΩ·cm, 89.39% lower than that of copper paste. The surface of conductive film of this nanotube-copper composite paste is flatter and denser than that of copper paste, causing the formation of the closer contact among conductive phases. Numerous carbon nanotubes cover the surface of copper powder particles, filling the gap between copper powder particles. Meanwhile the existence of a strong attraction among carbon nanotubes results in the formation of a huge network structure and a large number of conductive "bridges" between copper powder particles, enhancing the conductive properties of composite paste.