Controllable Fabrication of Submicron-Thick Polyimide Films by Piezoelectric Spraying

Polyimide (PI) films have been extensively utilized as flexible substrates in various cutting-edge fields, including aerospace, microelectronics, and healthcare. However, existing techniques to prepare PI films typically exhibit a limited degree of thickness controllability, surface uniformity, and mechanical stability, which hardly meet the requirements in high-precision flexible devices and integrated systems. Here, a piezoelectric spray coating method is proposed for preparing high-quality PI films with controllable thickness. We have investigated the atomization effect and key parameters in the spraying process, such as viscosity, amplitude, liquid feed rate, speed, air pressure, and spraying cycles. We can precisely control the thickness of the resultant PI films by optimizing these parameters. The prepared PI films exhibit superior characteristics, such as high smoothness, bubble-free surfaces, uniform thickness, high thermal stability, and excellent optical properties. With these advantages, such an approach may contribute to developing high-performance flexible electronics.