| Currently, RFID antenna is tending to be smaller and more flexible, and traditional manufacturing techniques could not meet these requirements any more. Hence, to find a new RFID antenna manufacturing technology with low cost, high accuracy and flexibility is very important.Nowadays, ink-jet printing technology based on nano-conductive ink is the major research direction of RFID antennas manufacturing. Commercial inkjet printer is usually selected as antenna printing equipment in RFID antenna inkjet printing technology, however there are many disadvantages such as, poor controllability during the printing process, poor applicability of the base material, difficult to disassemble and maintain the micro-nozzle, all of them restrict the application of inkjet printing technology in the field of RFID antenna manufacture. To solve these problems, an RFID antenna inkjet printing system based on the digital micro-droplet ejection was proposed, application experiments were conducted with this system.This RFID antenna inkjet printing system is consist of a droplet generating devices, worktable and control system. Piezoelectric ceramic is used as piezoelectric actuator to drive micro-nozzle, and dual motor is used to drive the worktable. The system control parameters and the antenna pattern file is processed and then sent to the control system through the PC interface and serial communication. In the lower system, FPGA is used as the main chip, its embedded Nios II soft-core is used as CPU. A programmable system-on-chip is built to generate drive waveform and do secondary development of the antenna pattern files, to realize RFID antenna pattern inkjet print which is high precision and easy to control.Basic experiments were conducted using no particle conductive ink Jet-600C as conductive ink based on this system, conductive ink was injected on a PET film coated with the hydrophobic film, RFID tag antenna formed after sintering in 140℃. Conductive ink dilution ratio, micro nozzle outlet diameter, drive waveform amplitude, drops overlap and the concentration of hydrophobic material were studied to find their influence on the droplet diameter of the micro droplet, regularity degree of the printed line and conductive properties in experiments. Designing and simulating a pole antenna, and inject the dipole antenna for 3 times under the conditions that the voltage was 60V, exit inner diameter micro nozzle was 80μm. The performance parameters of the antenna detected by vector network analyzer were close to the simulation values. Results in experiments show that the system can realize RFID antennas inject printing, and meet the demands of high-precision, low-cost, flexible manufacturing.The research of printing spiral wire with PEDOP:PSS conductive solution was conducted. RC photographic paper was used as substrate in this experiment. The research indicated that the system was available for RFID inkjet printing with different conductive inks and substrate, and has some potential in other flexible electronic productions. |
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