Development of polyimides for opto-electronic integrated circuit

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From the molecular orbital calculation of the model compounds, it was evident that a strong intramolecular charge transfer characterized the first excited state, and this nature based on the predominant HOMO-LUMO transition contributed to the coloration of aromatic polyimides. Various kinds of tetracarboxylic dianhydride with a polyalicyclic structure were synthesized and polycondensated with aromatic or aliphatic diamines. The fully imidized aliphatic polyimide films were soluble in organic solvents such as DMAc. The polyimides had good thermal stability with the 5% weight loss temperature range of 450-500℃ and exhibit higher Tg's over 290℃. The flexible polyimide films possessed a tensile modulus range of 1.5-2.6 Gpa and a tensile strength range of 52-96 Mpa. These films were entirely colorless, and the transparencies in the visible region were over 85%. The polyimides had an average refractive index range of 1.52 to 1.62, and the birefringencies were nearly zero. The dielectric constants that were estimated from the refractive index according to the modified Maxwell equation were 2.55-2.89. These polyimides may be of interest for microelectronics or opto-electronics applications.