One-step curing process of conductive paste based on a UV pulse laser for a frequency selective surface.

Abstract

A frequency selective surface (FSS) is a two-dimensional periodic array structure, in which a common structure is composed of conductive paste and metal film. An ultraviolet (UV) pulse-laser-induced curing of conductive paste towards FSS was used to simultaneously realize the efficient curing of conductive paste and the removal of surplus materials. Through simple defocus control of the UV pulse laser when irradiating the workpiece, this technology was capable of reducing the energy density and increasing the irradiation range, thus preventing the conductive paste from being ablated and achieving efficient curing. In this context, the curing process of UV curable conductive paste was systematically studied through the Ohmic resistance and bonding force of the cured conductive paste. The curing effects of various conductive paste thicknesses and different laser scanning times at a certain laser scanning speed were also analyzed. The results showed that, after a controllable defocusing treatment, the UV pulse laser could effectively solidify the conductive paste and realize the electrical connection of materials on both sides of the pattern. The peel strength of the conductive paste was greater than 7.1 N/cm. However, the pulse laser curing method needs a longer curing time when compared with the continuous UV curing method.