Laser-Induced Precision Etching of Copper-Clad Polyimide with UV Nanosecond Pulses for Flexible Thin-Film Antenna Fabrication

This paper presents a study on the fine processing of flexible thin film conformal antennas for use in aerospace and microelectronics applications. Current methods for processing these types of antennas have different degrees of defects, but the use of a UV-nanosecond laser offers several advantages, such as high photon energy, non-contact processing, and a small heat-affected zone. In this study, we conducted a technical analysis of the circuit structure of radar flexible thin film antennas through UV-nanosecond laser direct writing and achieved controlled processing of large-format radar flexible thin film conformal antennas. We built a UV-nanosecond laser processing system platform and carried out studies on both the single-line removal process and small-format fine removal. The surface roughness of polyimide was successfully reduced to 0.55μm, the contour accuracy was controlled to within 10μm, and high-quality processing of complex patterns was achieved. Based on these findings, we conducted research on the large-format flexible thin film antenna pattern splicing process and successfully controlled the contour error of large-format flexible thin film antennas within ±8µm, the splicing error within 2µm, and the surface roughness within 0.4µm. Furthermore, we obtained a result by removing copper plating in a non-conductive position. Ultimately, the flexible film processing method produces large-format flexible film antennas of high quality with little roughness, good surface consistency, and no noticeable processing markings at the splices.