The fluorinated polyimide PI(6FDA/HFBA.PP) was prepared by the reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) in 1-methyl-2-pyrrolidone/toluene. A multiblock copolyimide with both fluorinated and rigid-rod segments, PI(6FDA/ HFBAPP)(BPDA/2-DMB), was prepared by the addition of a second dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and a second diamine, 2,2'-dimethylbenzidine (2-DMB), to the polyimide main chain. The potential lithographic performance of photosensitive polyimides composed of nonphotosensitive fluorine-containing polyimides and photosensitive diazonaphthoquinone (DNQ) was studied on the basis of a new imaging principle recently proposed by our laboratory, that is, reaction development patterning. Neat PI(6FDA/HFBAPP) showed a low dielectric constant (E) of 2.41 and a low dissipation factor (tan delta) of 0.0027 at 20 GHz, and a 10-mum resolution of the fluorinated polyimide/DNQ system was demonstrated with reactive development with a solution including ethanolamine after ultraviolet exposure. Although slight changes in the dielectric properties were observed in the presence of DNQ residues, these values (epsilon = 2.63 and tan delta = 0.0033 at 20 GHz) were low enough for use in microelectronic applications. However, PI(6FDA/HFBA.PP)(BPDA/2-DMB), having a lower coefficient of thermal expansion (CTE; 33 ppm/degreesC) than PI(6FDA/HFBAPP) (49 ppm/degreesC), exhibited good positive photosensitivity, whereas the relatively low-CTE multiblock copolyimide displayed a much higher epsilon value (3.48 at 1 MHz) than the highly fluorinated polyimide (2.88 at 1 MHz). A film consisting of PI(6FDA/HFBAPP)(BPDA/ 2-DMB) and the remaining DNQ derivatives showed a CTE value comparable to that of the neat polyimide film. (C) 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 861-871,2003.