Synthesis of Low Dielectric Constant Polyetherimide Films

As the demand for downsizing in microelectronics is increasing, devices require material with lower dielectric constant accordingly. The dielectric constants for most polyimide (PI), including polyetherimide (PEI), films are ～3.5. In this study, we modified the PEI by incorporating various monomers (fluorinated dianhydride 6FDA and phenylene ether diamines) to reduce the dielectric constant. The dielectric constants of synthesized PEIs decreased with increasing amounts of 6FDA content and phenylene ether units. The T_g decreased gradually with PEI containing longer phenylene ether units, but increased with the content of 6FDA. The thermal decomposition temperatures at 10% weight loss were ～550 °C, indicating that these PEIs have high thermal stability. Both the tensile strength and the modulus decreased with the PEI containing longer phenylene ether units. The PEI synthesized with 40% 6FDA dianhydride and 1,4-bis(4-aminophenoxy)benzene (pBAB) diamine has the lowest dielectric constant of 2.78 at 1 MHz.