Tin-containing polyimide films have been fabricated having surface resistivities of 105-108 /square and thermal stabilities >500 °C. Most of these films are homogeneous, and all appear tough and flexible. A tightly bound layer of Sn02 on the air-cured, atmosphere side of the film appears to be responsible for the lowered resistivities. Migration of the tin complex during curing followed by reaction with H20 and possibly 02 yields the Sn02 surface layer. Glass sides of films and N2-cured films are nonconductive. The Sn02 layer on air-cured films has been found to be photoactive.
Polyimide films based on either 3, 3′, 4, 4′‐benzophenone tetracarboxylic acid dianhydride or pyromellitic dianhydride with 4,4′‐oxydianiline have been doped with copper(I) and copper(II) complexes. High‐quality, flexible, glass‐cast films have been obtained which exhibit increased softening temperatures and lower polymer decomposition temperatures. The atmosphere and glass sides of the films are quite different. The copper(I) dopant is oxidized on the air side of the film, while the glass side contains predominantly copper (I). In the copper(II) case most of the copper appears on the air side as a silvery substance in the Cu(II) state. Chemical as well as ion etching can remove this material. Electrical resistivity of the copper(II)‐doped films is decreased by three to five orders of magnitude relative to the polymer alone.
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