Ionic-bonded negative photosensitive polyimides having pendant aminoalkyl (meth)acrylamide groups

Abstract

Soluble polyimides having pendant carboxyl groups were prepared by a direct one-pot polycondensation of various acid dianhydrides with 3,5-diaminobenzoic acid and bis[4-(3-aminophenoxy)phenyl]sulfone in the presence of γ-valerolactone/pyridine catalyst in 1-methyl-2-pyrrolidone (NMP)/toluene mixture at 180 °C. The pendant carboxyl groups were blocked with photopolymerizable (meth)acrylamides, N-[3-(dimethylamino)propyl]acrylamide (DMAPAA), N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA), or N-[3-(diethylamino)propyl]methacrylamide (DEAPMA), through ionic bonding at room temperature. The ionic-bonded photosensitive polyimide films containing photosensitizer Michler’s ketone (MK) and ethylene glycol dimethacrylate (EGDMA) as an external multifunctional cross-linker gave negative-tone behavior by near-UV irradiation followed by development with 10% aqueous NaOH at 25 °C. The SEM photograph of the resultant images showed fine patterns (line/space 20/20 μm) with ∼15 μm in film thickness. The sensitivity of photosensitive polyimides with DMAPAA or DMAPMA was higher than that of photosensitive polyimides with (meth)acrylate esters such as 2-(dimethylamino)ethyl acrylate (DMAEA), 3-(dimethylamino)propyl acrylate (DMAPA), 2-(dimethylamino)ethyl methacrylate (DMAMA), and 2-(diethylamino)ethyl methacrylate (DEAMA).