Semi-insulating polyimide as a high resistive material

A new polymer, designed by extending π electron systems along the molecular chain, has been studied from the view point of a high resistive or semi-insulating material. A high resistive polyimide thin film of 10¹²-10¹⁴ Ω cm without a large absorption current below 40 kV/cm has been obtained by the vapor deposition polymerization with pyromellitic dianhydride and 4,4´-diaminostilbene. It is also found that an increase in the orientation of molecular chain axis with decreasing thickness yields lower resistivity and that the orientation of pyromellitdiimide has little effect on the resistivity