Investigation of polyimide/carbon nanotube nanocomposites for high temperature electronic packaging applications

Polyimide (PI) has been widely used in microelectronics as a substrate or interlayer, and the high glass transition temperature Tg (>300°C) of PI makes it suitable for high temperature applications, such as devices in automotives, power electronics, measurement and control components of aircraft engines and well drilling. In this paper, surfactant-assisted polyimide/carbon nanotube (PI/CNT) nanocomposites were prepared by in-situ polymerization. The effects of surfactant on microstructure, electrical and dynamic mechanical properties of polyimide nanocomposites were investigated. The FT-IR results showed that all the nanocomposites gave almost the same vibration bands as those from polyimide. The microstructures of PI/CNTs were optimized by the presence of certain amounts of surfactant and the storage modulus of a surfactant-assisted PI/CNTs film is 67% higher than that of a film without the surfactant. However, the excessive surfactant decreases the light transmission of the PI/CNTs films. The conductivity of the PI/CNT film with 1wt% of CNTs assisted by a surfactant was 3.36×10^-7S/cm, which reached the antistatic criterion of thin films for space applications (1×10 ^-8S/cm). In addition, reliability studies of 85°C/85% relative humidity tests and pressure cooker tests (PCT) on the PI/CNT nanocomposites demonstrated the incorporation of a certain amount of surfactant is helpful for improving the resistance property under harsh environments, which thus proved the potential applications of such materials for high temperature electronic packaging applications.