A photoinitiator-free photosensitive polyimide with low dielectric constant

A series of photoinitiator-free photosensitive polyimides (PSPIs) with lower dielectric constants have been synthesized by reaction of fluorine aromatic diamine, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropro-pane diamine (AHHFP) with 3,3',4,4'-benzophenonetetra-carboxylic dianhydride (BTDA) and a mixture of various mole ratios of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-(hexafluoroisopropylidene)diph-thalic anhydride (6FDA) by using solution poly-condensation reaction at room temperature and further imidization at 180°C. These aromatic polyimides were further acrylated via a reaction with acryloyl chlroride in the presence of triethyl amine to produce negative photoinitiator-free PSPIs. All the photoinitiator-free photosensitive polyimides were characterized by FTIR and NMR while their morphologhy was evaluated by X-ray diffractions study. These newly synthesized PSPIs were evaluated to determine their electrical, thermal, and photolithographic properties. The PSPI (AHHFP-BTDA-6FDA [1 : 0.5 : 0.5]) with high mole ratio of 6FDA showed lower dielectric constants of 2.420 at 1 kHz and 2.170 at 1 MHz in capacitance and optical methods, respectively. Further, the acrylated AHHFP-BTDA showed the highest photosensitivity than other PSPIs.