Development of in-plane orientation in pyromellitic dianhydride-oxydianiline polyimide film on substrate during thermal imidization

The development of in-plane orientation in pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide film coated on silicon substrate during thermal imidization was investigated by means of FT-IR spectroscopy. The increase in thermal imidization temperature caused the decrease in the degree of in-plane orientation in spite of the increased chain rigidity. It suggests that the chain immobilization limit the development of the in-plane orientation during thermal imidization. The residual solvent was found to decrease the degree of in-plane orientation probably due to the increase of the chain immobilization rate as indicated by the quantitative measurements of the degree of imidization and the residual solvent content as a function of imidization time at various temperatures.