Low‐Dielectric and Submicron‐Resolution Photosensitive Polyimide Substrate for Large‐Scale Pattern Customization and Low‐Signal‐Loss Transmission with Nanotesla‐Scale Quantum Sensing Potential

Abstract Photosensitive polyimide (PSPI) integrates photoresist and dielectric interlayer functions for efficient electronic fabrication, yet suffers from limited resolution and elevated dielectric constants, particularly in advanced integrated circuits (ICs). In this study, through integrated molecular design and component screening, a novel PSPI system incorporating intrinsically low‐polarization photosensitive groups and efficient chemical amplification is found to exhibit low dielectric properties (ɛ = 2.241, tanδ = 0.0137 at 10 GHz), submicron‐level resolution (≈880 nm), low thermal imidization temperature (180°C), and low coefficient of thermal expansion (26 ppm K −1 ). This PSPI system is fully compatible with modern IC manufacturing processes, and its superior photosensitivity (33.15 mJ cm⁻ 2 ) and high contrast (3.03) further support laser direct writing. Moreover, as an encapsulation material and dielectric interlayer in flexible multilayer circuits, the PSPI system demonstrates robust bending durability and enhances high‐frequency signal integrity with minimal parasitic capacitance. Coupled with nanodiamond nitrogen‐vacancy centers, low‐dielectric PSPI‐based circuit boards significantly improve quantum sensing and imaging, providing higher signal fidelity and enabling precise nanotesla‐scale measurements in weak magnetic fields. This breakthrough advances the resolution of PSPI to an unprecedented nanometer scale while maintaining exceptional dielectric performance, establishing it as a pivotal enabler for next‐generation flexible integrated systems requiring precise signal transmission.