A Study on Low‐Temperature Curable Photosensitive Polyimides Containing N ‐Heterocyclic Moieties

ABSTRACT Photosensitive polyimide (PSPI) can simplify the manufacturing process by integrating photopatterning capability with favorable comprehensive performance in the cured film, such as heat resistance, tensile modulus, toughness, and chemical resistance, compared with the conventional photoresist. Considering the warpage of wafer and thermal decomposition of the components in the photoresist, low‐temperature curable PSPI (≤ 250°C) is highly desirable. Incorporating curing catalyst moieties into the polymer chain has the potential to enable PSPI to be cured at low temperature while simultaneously ensuring favorable comprehensive performance. However, achieving an optimal balance among these properties remains a significant challenge. Herein, we introduce the electron‐withdrawing aromatic group 2,2′‐bipyridine and the electron‐donating group piperazine to address this issue. The incorporation of 2,2′‐bipyridine facilitates low‐temperature curing at 250°C and high transparency at the PSPAA stage, beneficial for photolithographic performance with a high resolution of 12.5 μm. After thermal imidization, it leads to enhanced chain rigidity and intermolecular interaction. The as‐prepared PSPI exhibits a low CTE of 48.7 ppm K −1 , high tensile strength and tensile modulus of 76.5 MPa and 2.1 GPa. Introducing the electron‐donating group piperazine yields PSPI with a resolution of 11.3 μm and an elongation at break of 36.5%.