Study On Direct Writing Of Conductive Circuits On The Surface Of Molded Material

In recent years, with the rapid development of microelectronics technology and theextensive application of polymer materials, traditional fabrication technology formicroelectronics can not meet the requirements of electronic products developing towordsdiversification, integration and miniaturation. Therefore, improvement and innovation of thefabrication technology have attracted many research interests. Direct writing technology isbecoming a researh hotspot in the production of conductive circuits on the surface of moldedmaterial because of its maskless, high-precision and high-flexibility advantages. In this paper,the fabrication of conductive lines on the surface of polymer was explored by the use ofmicro-pen technology and laser direct writing technology, which provided a novel methodfor the fabrication of three-dimension (3D) metallic lines on the molded structure.In this paper,3D microstrip antenna, which was a coposite of double-arm planarequiangular spiral antenna and double-arm conical logarithmic spiral antenna, was fabricatedby the direct writing deposition of conductive silver paste on the the surface of polyimide (PI)using micro-pen direct writing technology. The two spiral antennae were modeled andfabricated by direct writing respectively at first and then integrated together. Theexperimental results showed that the3D microstrip antenna was prepared sucessfully withuniform and dense conductive film, good consistency, electrical conductivity and adhesion.This method has a simple fabrication process and short production cycle.The fabrication process of conductive circuits on the surface of polycarbonate (PC) bythe use of pulse laser assisted electroless plating was presented. It included the followingprocdures. First, an activator was presetted on the surface of polycarbonate of moldedstructure by depositing. Then a pre-designed circuits pattern was etched by a pulse laser witha wavelength of1064nm controlled by the CNC system. Next, the patterned polycarbonatewas rinsed and the electroless plating of metallic layer was carried out. Thus, the conductivecurcuits was obtained. The effect of experimental parameters including laser power density,scanning speed and scanning line length on the etching and morphology of the metallic layerwas explored. Through physical and chemical characterization and measurements includingmorphology, roughness, contact angle, attenuated FT-IR and energy dispersive spectrometry(EDS), the mechanism of pulse laser assisted electroless plating was proposed. Physical roughening and slight melting of the PC, and absorption and diffusion of activator on the PCwere considered to be the main reasons for the realization of the electroless plating and thegood adhesion of metallic layer with the substrate. Testing results showed that all of thesurface morphology, adhesion and electrical conductivity of conductive lines was excellent,which demonstrated that this technology had many merits of masklessness, direct writingfabrication, high flexibility, high selectivity, simple process, and low cost.