Study on Pulse Laser Etched Interface Characteristics of Metal Thin Film/Organic Material Structures for Space Antennas

To study the characteristic changes of metal film/organic material interface during pulsed laser etching, the 1 µm thick metal Cu film was prepared on the surface of typical organic material （Polyimide PI） by physical vapor deposition. Short pulse （100 ns） and ultra-short pulse （290 fs） laser were used to remove part of the metal film on the surface. XPS and SEM were used to characterize the etched interface. The dielectric properties of the samples in high frequency band（4 ~ 18 GHz） and solar transmission spectrum （200 ~ 2 000 nm）were tested. The results show that there are similarities and differences in the interface characteristics of Cu/PI, which is composed of materials with very different thermal properties, after nanosecond and femtosecond laser etching. The commonness is reflected in that the dielectric constant and loss factor values of the two kinds of samples are slightly higher than those before etching, which is caused by the particles of the metal film reverse deposition during the etching process and the carbonization of PI, a thin dielectric film formed on the new surface at the interface after etching. The difference is reflected in the microscopic morphology of the interface. Due to the difference in the etching mechanism of femtosecond and nanosecond laser, micro-structures are formed in the surface of the interface after femtosecond laser etching, resulting in a decrease of transmittance about 60% in the visible/near-infrared range from 500 to 2 000 nm, while the transmittance does not change significantly after nanosecond laser etching.