Fabrication Of Flexible Circuit Based On Electrohydrodynamic Printing And Its Application In Rfid

In recent years,with the rapid development of electronic industry,the world has entered a new era of intelligent manufacturing.Traditional electronic integrated circuit preparation can't meet the requirements of sustainable development,and can't be used to prepare flexible electronic devices.In this situation,the printing electronic technology has become a new research.But the resolution of traditional printing electronic technology is low,the compatibility of ink and printing technology needs to be deeply analyzed,and the printed circuit needs post-processing.In this paper,the flexible circuit was made by using high-precision electrohydrodynamic printing,and the process parameters of electrohydrodynamic printing and post-pressing sintering were studied.Besides,the application in radio frequency identification(RFID)was realized.Silver nanoparticles were selected as conductive materials of conductive ink,silver nanoparticles were prepared by chemical reduction method.The phase,size and morphology of silver nanoparticles were analyzed.To improve the dispersibility of conductive ink,the solvent composition and content of conductive ink were investigated.Measure the wetting angle between conductive ink and substrate,and analyze the printability of conductive ink.The flexible circuit was fabricated by electrohydrodynamic printing.And the process parameters,including nozzle diameter,loading voltage and nozzle height,were investigated.The printed flexible circuit was sintered.The sintering process parameters,including sintering temperature and sintering time,and the effect of sintering treatment on the conductivity of the circuit were investigated.The structure of the UHF RFID antenna was designed,the RFID antenna pattern was fabricated based on the electrohydrodynamic printing,and the RF performance of the RFID antenna was simulated by using HFSS.The results showed that the silver nanoparticles were uniform in size and shape,and the average particle size was 50 nm.Different boiling point of solvents,including deionized water,ethanol,isopropanol and ethylene glycol were in the preparation of conductive ink.The existence of ethylene glycol was confirmed,which could improve the dispersibility of conductive ink.The conductive ink with moderate wettability was obtained by measuring the wetting angle between various solvents,conductive ink and substrate.When the nozzle diameter was 160 ?m,the jet process could be controlled by adjusting the voltage and the printing height.When the bias voltage was between 500 V and 600 V,the width of the printing line could be adjusted.When the nozzle height was 300 ?m,the printing line was the most uniform and straight.When the sintering temperature reached 140 °C and the fixed sintering time was 30 min,the square resistance of the flexible circuit reached the minimum value of 0.42 ?/sq.When the sintering temperature was 140 °C and the sintering time was 30 min,the square resistance became stable.In the bending test,with the increase of bending times,the resistance of the flexible circuit increased gradually.The printed flexible circuit could withstand 1000 bends with the resistance increasing rate not more than 50% as the reference value,which showed that the flexible circuit has mechanical stability.The structure pattern corresponding to the frequency band(920 MHz ? 925 MHz)of RFID antenna was designed.The printed RFID antenna was realized by using the electrohydrodynamic printing,and the RFID tag antenna had excellent electrical performance.The RF performance of the RFID tag antenna was analyzed by using ANSYS HFSS,including echo loss,far field gain graph(E plane),Smith chart and 3D pattern.There was no deviation between the RFID antenna's central frequency and the target's central frequency.The minimum return loss of the antenna was-16.78 d B,and the frequency range was 885 MHz ? 967 MHz,which was less than-10 d B.