ABSTRACT
Polyimides have gained increasing importance because of their high temperature properties, low dielectric constants, inertness to solvents, and long-term stability. Although the synthesis of an aromatic polyimide was first reported in 1908 [1], it was not until the late 1950s that a successful commercial route to high-molecular-weight polyimides was first patented by DuPont [2–9]. The first commercial polyimide film was introduced by DuPont in the late 1960s. Since then, polyimides have increased in commercial importance. Thermoplastic polyimides that can be melt processed have been developed for some injection molding and composite applications. Products such as Vespel can be sintered to form three-dimensional parts such as high-temperature seals. The most notable use of polyimides is in the electronics industry, primarily in applications as films or coatings. The use of polyimides in microelectronics applications dates back to the early 1970s [10–13]. In the electronics industry, polyimide coatings are used in a variety of interconnect and packaging applications, including passivation layers and stress buffers on integrated circuits and interlayer dielectrics in high-density interconnects on multichip modules. A complete review of the historical development of polyimides has been given by Sroog [14].
