Copolyimides with siloxane moieties in the main chain were synthesized by solution polycondensation of 1,3-bis(3-aminopropyl) tetramethyldisiloxane (APMS), oxydianiline (ODA) with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) in N-methyl-2-pyrrolidone (NMP). The adhesion properties between copolyimides and silicon wafer were improved significantly with incorporation of siloxane moiety into polymer chain.

Photosensitive copolyimide precursor was obtained by further reaction of silicon-containing copolyamic acid with 2-isocyanatoethyl methacrylate (IEM). The insoluble fraction of photosensitive copolyimide precursor reached 90% after 10 min of irradiation with UV light. In comparison, the thermal imidization of irradiated photosensitive copolyimide precursor was more difficult than that of silicon-containing copolyamic acid. A longer heating time or higher imidization temperature was required.