Development of polyimides for opto-electronic integrated circuit

从模型化合物的分子轨道计算中可以明显看出，第一激发态具有很强的分子内电荷转移特征，这种基于HOMO-LUMO跃迁的性质有助于芳香聚酰亚胺的着色。合成了多种具有多脂环结构的四羧酸二酐，并与芳香族或脂肪族二胺缩聚。完全亚酰化的脂肪族聚酰亚胺薄膜可溶于DMAc等有机溶剂。在450 ~ 500℃范围内，聚酰亚胺的热稳定性较好，失重率为5%，在290℃以上表现出较高的Tg。柔性聚酰亚胺薄膜的拉伸模量为1.5 ~ 2.6 Gpa，拉伸强度为52 ~ 96 Mpa。这些胶片完全无色，可见光区的透明度在85%以上。聚酰亚胺的平均折射率为1.52 ~ 1.62，双折射率几乎为零。根据修正的麦克斯韦方程，由折射率估算出介电常数为2.55 ~ 2.89。这些聚酰亚胺可能对微电子或光电子应用感兴趣。

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.