ABSTRACT Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Most of the investigations into polyimides have concentrated on wholly or partially aromatic systems. Although aromatic polyimides possess excellent thermal stability, chemical resistance, and mechanical properties, there are a number of obstacles that hinder extending their applications in optoelectronic materials and high-speed multilayer printed wiring boards like their insolubility in common solvents in the fully imidized form, the light or dark-yellow color of their films caused by intra- and intermolecular charge transfer (CT) interactions, and their high dielectric constants. As a result, fully aliphatic and alicyclic polyimides (API) are currently being considered for their applications in optoelectronics and interlayer dielectric materials because of their higher transparencies and lower dielectric constants, which result from their low molecular density and polarity and low probability of undergoing interior intramolecular CT. In this article we will review recent research progress in the synthesis and characterization of fully aliphatic polyimides which can be applied in microelectric and photoelectronic industries.
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