A series of different acid value polyimides with carboxyl groups in the ends of main chain was synthesized and used for the three-component photopolymers, consisting of the polyimide, a vinyl ether monomer, and a photo-acid generator (PAG). This polyimide acts as a positive-type resist with the process of prebaking (PB), exposure to light, and post-exposure baking (PEB). The effect of the acid value correspond to molecular weight on the characteristics of the photopolyimide, such as sensitivity

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... and contrast, was investigated. An increase in the acid value and a decrease in the molecular weight enhance the increment of sensitivity based on solubilization rate by cleavage reaction. This positive-type photopolyimide showed a sensitivity of 137 mJ I cm2 and a gamma value of 2.9.