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Printing technology plays an important role in RFID tag manufacturing. It will be a very useful attempt for printing technology to participate in RFID tag manufacturing. With the further study of printing process parameters and the continuous improvement of conductive ink formula, printing technology will play an important role in RFID tag manufacturing

rfid tag, namely radio frequency identification tag, is a kind of smart card. RFID is an identification method that uses radio frequency for non-contact two-way communication. It appeared during the World War II, began to be used in the 1970s, and began to be used on a large scale in the 1990s. Technology has been widely used in various fields of our life, such as the simplest access card, bus card, campus card, etc. In the application of RFID technology in the retail industry, a widely recognized model is the "future store" model

in future stores, all goods will be labeled with RFID tags. PCI pointed out in the report that there are two places where customers are exposed to RFID technology in the store: the so-called smart shelf and smart cashier. The smart shelf is equipped with an RFID tag scanner on the shelf, which can automatically prompt the goods to leave the shelf and place them in the wrong position, so as to solve the problems of timely replenishment and correct loading; The traditional cash register no longer exists in the store, but is replaced by an intelligent cash register. The smart cashier can be realized through a screen at the exit where the RFID tag scanner is installed. When the customer's cart passes through the screen, all purchased goods in the cart will be scanned instantly, and the intelligent cashier will automatically transfer the total cost of all goods from the customer's credit card. This makes it easy for customers to check out, and no longer need to wait in line in front of the traditional cashier for a long time

I. cost barriers of RFID tags

from the above application mode, we can see that RFID tags bring us more convenient and efficient consumption life. However, there is still a long way to go before every commodity can be labeled with RFID tags. One of the bottlenecks here is that the cost of RFID tags is relatively high. At present, the cost of each label has fallen below US $1, reaching 20 ~ 70 cents. It doesn't matter for high-priced products, but it will be regarded as a cost barrier for many low-cost goods such as toothbrushes and pencils. Therefore, to promote RFID tags in an all-round way, we should reduce the manufacturing cost of RFID tags on the premise of ensuring the performance of RFID tags

II. Advantages of printing technology in tag cost

rfld tags can be divided into three categories: passive RFID tags, semi-active RFID tags and active RFID tags. RFID tags on retail packages are generally passive RFID, which is a passive RFID tag, because it needs to receive the electromagnetic signal from the reader, induce the current, and then send the electromagnetic signal to the reader to realize the information transmission between the tag and the reader. The structure of this label is generally: substrate, chip and built-in antenna (coil). At present, the coil manufacturing methods include: copper wire winding method, chemical corrosion method, electroplating method and direct printing method. Among these four methods, it is worth highlighting that these five factors play a decisive role. The direct printing method is developed because it has the advantages of high-speed printing of antennas and low cost of consumables, which can significantly reduce the cost of RFID tags

III. driving force of conductive ink

direct printing antenna 4 Conductive ink is an important driving force in the two color technology of double window lipstick and green. Without the development of conductive ink, there would be no application of printing technology in RFID tag manufacturing. Conductive ink is composed of some conductive particles, resins or more special raw materials, such as conductive polymers. After the conductive ink is printed on the substrate and dried, due to the smaller distance between the conductive particles, the free electrons move along the direction of the applied electric field to form a current, which has good conductivity, so that the ink acts as an antenna. Ink quality is of great significance to improve conductivity and reduce ink consumption. A good conductive ink formula requires good printability, strong adhesion, low resistivity, low curing temperature and stable conductivity after printing

IV. research on direct printing antenna technology

at present, the method of direct printing antenna is still in the research stage. During the antenna printing of RFID tags, the antenna coils of RFID tags with different operating frequencies will correspond to different turns, coil thickness and the distance between each turn (for example, HF band uses a 13.56MHz chip, which usually requires that the number of turns of coils is 6 and the thickness is about 20 μ m。 The UHF band uses 868mhz and 950mhz chips, and the coil section thickness is about 4 μ m。), Therefore, the thickness of the printed ink layer, the width of each line and the figure outline after drying have strict tolerance range (for example, the error of two overlapping overprint must be within 0.1mm). When studying the direct printing of antenna by silk screen printing, the following beneficial experiences are obtained: the hexagonal hole shape is used for hole selection, which is conducive to the complete transfer of conductive ink; Conductive ink solvent based ink is better; Create excellent ink drying conditions (e.g. reduce the wind speed in the oven, the heating temperature is 140 ℃, and the heating time is between 30 seconds and 120 seconds), which is conducive to the accurate forming of the graphic outline of the printing coil. At present, a rotary printing equipment company in Switzerland has created a special production line for smart label printing. In the experiment of direct printing RFID tags by gravure printing, Stuttgart Media University, Germany, obtained the following beneficial conclusions: the best plate making method is to use the electronic engraving method of diamond, and the resolution is selected at 5080dpi. At this time, there are almost no jagged edges, and the required units can be accurately transmitted; The image file format required for front-end plate making uses bitmap format, so that the graphic information is not easy to lose; For the point structure, it is necessary to select a special open type acupoint which is different from the traditional acupoint. If the traditional hole is used, the wall between the holes will separate the conductive ink and cannot form a coherent path; The open hole can not only keep 0 250kg wall, but also easily solve the problem of wall separation ink. It will be a very useful attempt for printing technology to participate in RFID tag manufacturing. With the further study of printing process parameters and the continuous improvement of conductive ink formula, printing technology will play an important role in RFID tag manufacturing

reprinted from: Book Industry Forum

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