Miscibility behavior and reequilibration of binary poly(amic acid) mixtures

Abstract

Aromatic polyimides have found extensive use in microelectronic devices owing to their excellent thermal, mechanical, and electrical properties. The properties of a given polymer do not always meet the specific requirements needed for optimum performance in specialty applications. In order to achieve a combination of dersired properties such as good adhesion, high temperature dimensional stability mechanical properties characteristic of a tough material, and low thermal expansion coefficient, it is necessary to meld the properties of flexible and rigid polyimides into one system. Such modification of properties is generally achieved through the use of copolymers or polymer blends. Polymer blends are attractive due to the ease with which polymer properties may be modified and provide characteristics which may not be realized via a copolymerization approach. In the present study, miscibility of several binary poly(amic acid) mixtures were studied by optical microscopy in the condensed state prior to imidization and by dynamic mechanical measurements of fully imidized samples.