Analysis and Discussion on the most popular RFID n

2022-08-07
  • Detail

Analysis and Discussion on the efficient printing method of new RFID consumables

when the conductive ink is printed, the ink will penetrate into the pores, resulting in uneven distribution of the antenna impedance of the electronic tag. The higher the frequency, the more serious the problem is. The adhesion of printed antenna, chip packaging and ink characteristics are important factors to determine the service life of such products. Preface

with the growth of RFID market, the use of electronic labels has also increased exponentially. However, the real factor hindering the development of RFID industry is that the price cost of electronic labels is still high, while printed electronic labels are deeply expected by the market with their inherent cost advantages

printed electronic technology is widely used in soft electronics, organic displays, EMI prevention, paper batteries, RFID and other fields. Among them, RFlD passive electronic label printing faces the most technical problems

printing process

rfld passive electronic label printing mainly uses ink commonly known as conductive silver glue. Due to the use of silver powder in printing, the cost of silver glue has remained high due to the rising price of raw materials recently. As a result, the cost of printed electronic labels, which originally had the advantage of manufacturing cost, cannot be reduced for a while. However, in the long run, printed electronic labels will still be one of the best solutions for low-cost electronic labels in the future

in the printing process, there are four types of printing transfer inks: plate, gravure, relief and inkjet. The characteristics, quality and cost of each printing process are also different. If the characteristics of ink and printing substrate are considered, the combination of the process and material characteristics of electronic label printing will determine the printing place of each electronic label. Suitable production mode

plate printing

rfjd electronic label printing process has the most cases using this scheme. Plate printing is to sweep the conductive ink from the other side of the plate through the plate with a scraper, and the ink passes through the hole gap of the pattern on the plate and is stuck on the printed substrate. The printing ink for plate printing has a high viscosity, and the printing film thickness can reach up to 100um, while the printing film thickness of RFID electronic tag is only about 812um. The subsequent drying can be achieved by using advanced building materials such as integrated green building materials as the development focus of UV, IR and hot air

gravure printing

gravure printing is to fix a metal thin plate (gravure) engraved with a pattern on the printing roller on the printing machine, and transfer it to the printed substrate after being stained with printing ink. The ink viscosity of gravure printing is lower than that of plate printing ink. The ink film thickness control is the most accurate, and it can also meet the film thickness requirements for RFlD electronic label printing. Moreover, the printing speed is faster, which is very suitable for mass printing production. The disadvantage is that the equipment capital required to be invested is high

relief printing

relief printing is to fix a rubber thick plate (embossed) with a pattern on the printing roller on the printing machine, and transfer it to the substrate after being stained with printing ink. The ink viscosity of relief printing is lower than that of gravure printing, and the ink film thickness is much lower than that of the former two, and the problems encountered in printing conductive silver glue are the highest and the most difficult to overcome, but if various problems can be overcome. The price competitiveness of printing electronic labels directly on cartons is incomparable with the former two

inkjet printing

the development of inkjet printing technology is an emerging technology in recent ten years. The printing accuracy of its large inkjet printing equipment can be up to about 50um. This technology is also the most likely to successfully realize the direct printing of LC circuits in the manufacturing process, but the disadvantage is that the printing speed is slow. The cost of equipment and ink is also the highest among all printing processes, while the ink viscosity is the lowest among the four processes, and the film thickness control accuracy is the highest

characteristics of conductive silver adhesive ink

at present, the suppliers of conductive silver adhesive are mainly American and European manufacturers, while in Asia, there are Japanese and South Korean manufacturers competing. The ink characteristics are mainly composed of silver powder, and the amount of silver powder determines the characteristics of conductive impedance

substrate

in the process of electronic label printing, the most easily neglected part is the substrate of the electronic label. Generally speaking, the substrate of the passive electronic label is no more than PVC, pet, coated white paper, tile paper, etc. but if it is used in the UHF frequency band, the dielectric coefficient of the substrate material will greatly affect the RF impedance of the electronic label, so in 2 The usage and development trend of spring tension and compression testing machine with small and medium load this factor should be taken into account in the design of electronic tag antenna

when using tile paper as the substrate for printing electronic labels, the pores of tile paper are quite large and irregularly distributed. When the conductive ink is printed, the ink will penetrate into the pores, resulting in uneven distribution of the antenna impedance of the electronic tag. The higher the frequency, the more serious the problem is

yield

the so-called yield here, in addition to whether the electronic label of the finished product can be read by the reader/writer, users are more concerned about the application yield, which is the so-called stable reading distance, and the key reason affecting this yield is the RF impedance of the finished product. In addition, the adhesion of printed antennas, chip packaging and ink characteristics are important factors that determine the service life of such products

conductive impedance

the RF impedance characteristics of the printed electronic tag antenna will be determined by factors such as whether the solid parts of the ink are evenly distributed in the ink during printing, the film thickness after printing and the dielectric coefficient of the printing substrate. People in the printing industry know that the color difference or film thickness will change to a certain extent from the first printed piece to the last printed piece. If the dielectric coefficient changes due to the quality of the substrate, the addition or offset of the two changes will cause the impedance of the printed antenna of the electronic label to exceed the specification and produce defective products. The influence of printed passive antenna in HF is slight, but if this situation occurs in printed passive antenna in UHF, the probability of defective products will be greatly increased. Even if the addition or offset of the variation degree of the first two process variables does not make the printing impedance of the electronic tag antenna exceed the specification, it will still make the printed UHF electronic tag produce different reading distance results

adhesion

when a smooth and compact material is used as the substrate, the ink may be easy to peel off after drying, especially when the semi-finished product or finished product is curled, the film thickness after drying will peel off or break due to bending stress, but in this case, the adhesion of the ink can be improved by adjusting the resin in the ink

phytic packaging

the yield of the phytic process mainly depends on the RF characteristics of the encapsulated conductive adhesive and the positioning accuracy of the printed parts. Generally speaking, the accuracy of relief printing is the worst. If it can be considered in the process planning and initial equipment construction adjustment in the future, the yield of the phytic process will be effectively improved

life cycle

the life cycle of a printed electronic label is shorter than that of an electronic label made by etching, stamping or evaporation. The reason is that the baked and dried silver glue, after contacting with water molecules or sulfur molecules in the air, is very prone to oxidation or vulcanization, resulting in discoloration or blackening. If such printed electronic labels are used and affixed to goods that will be transported by sea, they will face more serious oxidation or deterioration. After the antenna is oxidized, vermiculated or vulcanized, the RF performance of the electronic tag will be affected by the depth of the change layer. Fortunately, the RF impedance will not change significantly until the thickness of the change layer reaches a certain depth

conclusion

when the above four printing methods are used for passive UHF electronic label printing, their costs can also reduce raw material consumption and process yield are different. Although the yield of gravure and relief printing technologies is low, the production costs and production capacity of these two technologies are very competitive. If there is a breakthrough in conductive ink materials in the future, the results of figure (1) will be completely improved. Comparison of printing cost and yield in addition, the cost of inkjet printing is still high due to the availability of computers for intaglio and relief printing technologies. However, if the cost of equipment investment is excluded, the price of conductive ink used for inkjet printing is similar to that used for intaglio and relief printing, and the process characteristics of low material loss and stable high yield make the overall production cost lowest. Since the performance of the printed antenna mainly depends on the conductive particle solid content of the conductive ink, the thickness of the printed film and other two process parameters, and these two parameters can control 74% of the process yield results, this shows that the yield of the printed passive electronic label technology will be deeply affected by the characteristics of the conductive ink material

Copyright © 2011 JIN SHI