Silver Nanopartiedes Based Ink With High Conductivity And Low Sintering Temperature And Its Application In Flexographic Printed RFID Antenna

To make conductive inks for a wider range of substrates,to further expand the application of printed electronics,conductive ink is required to have a high conductivity at low temperatures.It is very difficult to further reduce the cost of screen printed radio frequency identification?RFID?antennas due to the limitations of the ink layer thickness and printing speed.Compared with the screen printing,flexographic printing method has a faster printing speed,and the ink layer thickness is thinner,is expected to further reduce costs.This paper works on silver nanoparticles based ink with high conductivity and low sintering temperature and its application in flexographic printed RFID antenna,mainly including the study on the preparation and properties of silver nanoparticles based ink with high conductivity and low sintering temperature,the effects of different heat treatment methods on the morphology and electrical conductivity of the silver nanoparticles?Ag NPs?coating,and the application of Ag NPs conductive Ink in flexographic printed RFID antenna.In this paper,silver nitrate?AgNO₃?as the silver source,hydrazine hydrate?H₄N₂·H₂O?as the reducing reagent,polyvinylpyrrolidone?PVP?as the protective agent,the Ag NPs were synthesized by a liquid phase reduction method.Ag NPs with average diameters of 48±12,76±33,158±65 and 176±85nm were prepared by changing the dosage of AgNO₃.The results showed that with the increase of the amount of AgNO₃,the average particle size of Ag NPs was also increased.Ag NPs with average diameters of 181±87,158±65,110±41 and 81±35 nm were prepared by changing the dosage of PVP.The results showed that with the increase of the amount of PVP,the average particle size of Ag NPs was decreased.By studying the effect of purification and concentration on the content of PVP,we found that the content of PVP on the surface of Ag NPs remained unchanged after 4 times of treatment.The interrelationships of Ag NPs size distribution,the content of PVP,the melting morphology of Ag NPs based films and their conductivity have been studied in detail.It has been found that the content of PVP decreases as the Ag NPs size increasing.And the particles of the silver coating are more easily melted at lower temperature when the average size of Ag NPs is increased.And the electrical resistivity of the Ag NPs films decreases at the beginning?minimum,S3?158 nm??followed by an increasing as the Ag NPs average size increasing?48 to 176 nm?during the heat-treatment at temperatures from 60 to140?.Finally,the optimal electrical resistivity of 5.1??·cm was achieved by heat treatment at 120?for 10min,only 3.22 times of bulk silver.Significantly,such a high conductivity with relatively low temperature of the Ag NPs based conductive ink makes its widely applications in printed electronics possible.The influence of temperature on four kinds of Ag NPs conductive inks with different molecular weight of PVP and different conductivity was studied at60-240?.It is found that the resistivity of the conductive ink has gone through four stages in the range of 60-240?,the rapid decline in large areas-decline slowly-the sharp decline in small range-decline slowly.The effects of different heat treatment methods on the morphology and electrical conductivity of the Ag NPs coating were studied.The results showed that the resistivity of the Ag NPs coating treated with the hot plate was lower than that in the oven in the range of 60-150°C and the corresponding coating particles had a higher degree of melting,and the advantage is more obvious at low temperatures?60-90°C?.The effect of printing pressure,printing speed and ink viscosity on the performance of RFID antennas was investigated.The results show that the printing conditions for the Ag NPs particles conductive ink with a viscosity of1100 cp,printing pressure of 50 and printing speed of 20m/min when printed RFID antenna performance is the most superior.The circuit resistance of the RFID antenna is 270?,the width of the line is 864?m,the thickness of the ink layer is 1.81?m,and the ink layer has good flatness,and the adhesion is very good at 5B on PET.The performance of bending,hardness and alcohol resistance meet the requirements of the application.