Structure and properties of various poly(amic diisopropyl ester-alt-imide)s and their alternating copolyimides

Abstract

Several poly(amic diisopropyl ester-alt-imide)s have been synthesized, which are a new type of polyimide precursors. The precursors consist of amic ester and imide units alternatively on the backbone, so that they are hydrolytically stable as well as low shrinkable through thermal imidization. These precursors have an easy processability because of their good solubility in common solvents that are widely used as good solvents for most polyimide precursors. The precursors and their alternating copolyimides in films have exhibited structural orders that are estimated to have a dimension of 15–42Å (along the chain axis) and 8–16Å (along the lateral direction), depending upon the polymer backbone chemistry. However, all the precursors and resultant copolyimides were laterally packed in an irregular way. Their crystallinities were apparently low. These results might be attributed mainly to the bend or kinked units on the polymer backbone. In addition, properties of the precursors and their polyimides in films: optical and dielectric properties, glass transition, thermal imidization characteristics, thermal stability, thermal expansion and residual stress, were investigated in detail. Overall, the precursor polymers, as well as the resultant alternating copolyimides were characterized to have relatively good properties suitable for applications in the fabrication of microelectronic devices.