Room-temperature 3D printing of recyclable polyimide dielectrics for high-frequency antenna applications

Abstract

Polyimides with ultralow dielectric permittivity and loss are essential for the production of advanced high-frequency wireless telecommunications systems. However, most polyimides produced through one-step high-temperature imidization and molding are thermosetting and incompatible with microelectronics manufacturing. Herein, we develop a vapor induced phase separation (VIPS) assisted direct ink writing process for the room-temperature fabrication of three-dimensional (3D) polyimide dielectrics. A simple yet effective ink formulation composed exclusively of soluble polyimide (sPI) and solvents is presented. Upon extrusion, the ink undergoes rapid gelation and solidification via VIPS triggered by ambient moisture, followed by solvent exchange in liquid water to form sPI filaments with dense skins and microporous cores. By programmably adjusting nozzle trajectories, the macroscopic features of the filaments can be precisely controlled, enabling the fabrication of 3D sPI dielectrics with a porosity of up to 87 %. These materials exhibit an ultralow permittivity of 1.32 and a loss tangent of 0.005 at 1 MHz, surpassing the performance of many existing dielectrics. The 3D dielectrics are applied in the fabrication of coplanar waveguide antennas and thermal management systems, demonstrating their potential for high-frequency communication and advanced electronics. Furthermore, the 3D sPI prints can be fully recycled by dissolving the products in solvents and reprocessing them into new ultralow-permittivity dielectrics, offering a sustainable and low-carbon manufacturing strategy for the microelectronics industry. This work not only overcomes the limitations of traditional polyimide processing but also provides a new platform for next-generation high-frequency communication and electronic devices.