*Polyimide for Electronic and Electrical Engineering Applications*


### **Table 1.**

*Main radicals for dianhydrides (*reproduced from *[8]).*

electrical heater to give a biaxial oriented polyimide film. The transverse stretching is carried out at temperatures around 350°C to facilitate the imidization of PAA into polyimide. Such a procedure has been widely used for PI film production, and there has been significant patent activity in the past half century since the commercialization of PI films in 1960s. Up to now, most of the commercially available wholly aromatic PI films have been produced by such kind of procedure.
