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RFID technology and silk printing analysis

the printing of smart labels is very different from the printing of traditional labels. At present, the printing technology of traditional labels in China has reached a high level. There are many experienced enterprises in the trademark printing industry, which also produce many products with exquisite design and high quality. However, for smart labels, some people think that it has nothing special, as long as it is covered with a beautiful coat with ordinary labels, This is not difficult for printing enterprises with high-quality labels, but the high added value of smart labels that simply add a beautiful coat is worrying, otherwise it will cause. First, from the definition of smart labels, intelligence is a RF circuit composed of chips, antennas, etc; The label printing process makes the RF circuit have the appearance of commercialization. From the perspective of printing, the emergence of smart labels will bring higher gold content to traditional label printing. The chip layer of smart labels can be encapsulated and printed with paper, PE, pet and even textiles to make self-adhesive stickers, paper cards, hanging labels or other types of labels. Chip is the key of smart label, which is determined by its special structure and cannot bear the pressure of printing machine. Therefore, in addition to inkjet printing, the process of printing surface layer first, then compounding with chip layer and die cutting is generally adopted

(1) printing method. Silk printing is the first choice for printing, because the printing quality of silk printing in integrated circuit boards, film switches and other aspects cannot be compared with other printing methods. In smart label printing, conductive ink should be used, and nickel foil perforation is the better wire for printing conductive ink. It is a kind of high-tech wire. It is not a wire woven from ordinary metal or nylon threads, but a foil made of nickel foil by drilling holes. The holes are hexagonal, and round holes can also be formed by electrolytic forming. The whole surface is flat and thin, which can greatly improve the stability and precision of imprinting. It can be used to print high-tech products such as conductive inks, chips and integrated circuits. It can distinguish circuit line spacing of 0.1mm, and the positioning accuracy can reach 0.01mm. You can also choose 6. These are the key t/cm silk solvent plate printing. After printing conductive ink, dry it at 60 ℃

(2) application of conductive ink. Conductive ink is a kind of special ink. It can add conductive carriers to UV ink, flexo water-based ink or special offset ink to make the ink conductive. Conductive inks are mainly composed of conductive fillers (including metal powders, metal oxides, non-metallic and other composite powders), bonding agents (mainly synthetic resins, photosensitive resins, low melting point Plexiglas, etc.), additives (mainly dispersants, regulators, thickeners, plasticizers, lubricants, inhibitors, etc.), solvents (mainly aromatics, alcohols, ketones, esters, alcohol ethers, etc.). The ink is a kind of functional ink. In printing, there are mainly conductive inks such as carbon paste and silver paste. Carbon paste ink is a liquid thermosetting ink, which can protect copper foil and conduct current after film forming and curing, and has good conductivity and low impedance; It is not easy to oxidize, has stable performance, and is resistant to acid, alkali and chemical solvents; It has the characteristics of strong wear resistance, wear resistance and good thermal shock resistance. Silver paste ink is a liquid ink composed of ultra-fine silver powder and thermoplastic resin. It can be used on pet, Pt and PVC sheets. Xinda group's R & D team adopts internationally advanced extrusion and injection molding equipment, which has strong adhesion and covering power, can be cured at low temperature, controllable conductivity and low resistance. In addition, the conductive nano carbon ink can be added to the ink to make the conductive ink, and the metal powder (such as silver powder) in the conductive ink can also be made into nano silver powder to make the conductive ink. This kind of conductive ink not only prints thin, uniform and smooth film, excellent performance, but also saves a lot of materials

in smart label printing, conductive ink is mainly used to print RFID antenna, replacing the traditional metal antenna made by foil pressing method or corrosion method. It has two main advantages. First, the metal antenna made by the traditional foil pressing method or corrosion method has complex process and long production time of the finished product. The application of conductive ink to print the antenna is a high-speed printing method, which is efficient and fast. It is the first choice in printing antennas and circuits, which is both fast and cheap. Nowadays, conductive ink has begun to replace etched antennas in various frequency bands, such as ultra-high frequency band (860 ~ 950mhz) and microwave band (2450MHz). Antennas printed with conductive ink can be compared with traditional etched copper antennas. In addition, conductive ink is also used for printing sensors and circuit printing in smart labels. Secondly, the metal antenna made by traditional foil pressing method or corrosion method consumes and wastes metal materials, and the cost of raw materials of conductive ink is lower than that of traditional metal antenna, which is of great significance to reduce the production cost of smart tags

(3) unique process requirements. Smart label printing has its unique requirements for the production process. We should mainly pay attention to high yield, thick paper printing and composite processing

in terms of high yield, the value of smart labels is many times higher than that of ordinary printed labels, so it is particularly important to have a high yield of printed products while bringing high profits to enterprises. In particular, electronic universal data testing machine is the product of modern electronic technology and mechanical transmission technology. Many products require multi-color UV ink printing, polishing and gluing. Most labels with large printing volume are also processed by roll to roll printing or no interface printing. Due to many processing procedures, it also increases the difficulty of screening finished products

for thick paper printing, in the process of paperboard processing, it must be noted that the equipment must have good printability for 350g thick paperboard. During paperboard printing, the tension of the paper tape should be kept stable to ensure that the cumulative overprint error of printing is minimized. Therefore, if each picture is overprinted accurately, but the spacing between pictures has a large error, it will also cause trouble to the composite and die-cutting process after smart label printing

as for composite processing, it is a key process in smart label processing. In composite processing, it is not only required that the size between each label will not change due to the change of tension, but also for film materials, it is also required to consider the increase of label spacing caused by tensile deformation, and make appropriate adjustments

3. The standard of electronic labels is

(1) high sensitivity (i.e. high Q value)

(2) high decoding rate (the standard decoding rate is 1%)

(3) low resurrection rate after decoding (the resurrection rate should be 0 within 10 minutes)

(4) good adhesive adhesion

(5) good overall softness of soft labels. Although the standard is dead, to produce qualified labels, we must achieve high technology and fine technology. The technology of producing electronic anti-theft soft labels is not a single technology and process, but a combination of many aspects. It includes electronics/circuit, mechanical control, chemistry/chemical engineering, printing, etc

4. The technical parameters of the electronic label are as follows:

label parameters

specification 38mmx42mm 30mmX37mm . 50mmx50mm, etc

thickness 10 wires

frequency 8.2m up and down offset 0.1

q value 153

non decoding rate 1/10000

resurrection rate 1/1000

v. basic principle of radio frequency tag reading and writing equipment

radio frequency tag reading and writing equipment is one of the two important components of radio frequency identification system (tag and reader). According to the characteristics of specific functions, RF tag reading and writing devices also have some other popular nicknames, such as reader, interleaver, communicator, scanner, reader and writer, programmer, reading device, portable reader device, AEI device (automatic equipment identification device), etc

generally, RF tag reading and writing equipment should be designed according to the reading and writing requirements of RF tags and application requirements. With the development of RFID technology, RF tag reading and writing equipment has also formed some typical system implementation modes. The focus of this chapter is also to introduce the implementation principle of this reader

the reader/writer corresponds to the RF tag reader/writer. The reader/writer must send commands to the RF tag through the spatial channel between the reader/writer and the RF tag, and the RF tag will make necessary responses after receiving the commands from the reader/writer, so as to realize RF identification. In addition, in the RFID application system, generally speaking, the contactless collection of RF tag data through the reader writer or the tag information written into the RF tag by the reader writer should be sent back to or from the application system, which forms the application program interface between the RF tag reader writer device and the application system program. Generally, the reader/writer is required to be able to receive commands from the application system and make corresponding responses (echo the collected tag data, etc.) according to the commands of the application system or the agreed protocol

VI. RF antenna in smart tag

the type of RF antenna must be selected so that its impedance matches free space and ASIC. The directional antenna has less interference of radiation mode and return loss. The access control system can use passive tags with short operating range. In RF devices, when the operating frequency increases to the microwave region, the matching problem between the antenna and the tag chip becomes more serious. The goal of the antenna is to transmit the maximum energy into and out of the tag chip. This requires careful design of the antenna and free space as well as its connected tag chip matching. The frequency bands considered are 435mhz, 2.45 GHz and 5.8 GHz, which are used in retail goods

1. The antenna must be:

(1) small enough to be attached to the required items

(2) omnidirectional or hemispherical coverage directionality

(3) provide the most possible signal to the chip of the tag

(4) regardless of the direction of the object, the polarization of the antenna can match the inquiry signal of the card reader

(5) robust

(6) very cheap

(7) the main considerations when selecting an antenna are:

a, the type of antenna

b, antenna impedance:

c, RF performance applied to objects

d. RF performance when his articles surround the labeled articles that affect the normal use of the experimental machine

2. Possible choices

there are two ways to use it: 1) labeled items are placed in the warehouse, and there is a portable device, which may be handheld, to ask all items, and they are required to give information feedback; 2) Install card reading equipment at the door of the warehouse, ask and record incoming and outgoing items. Another major choice is active tags or passive tags

3. Optional antennas

in the RFID system with 435 MHz, 2.45 GHz and 5.8 GHz frequencies, there are several optional antennas, as shown in the table below, which focus on the size of the antenna. The gain of such a small antenna is limited, and the size of the gain depends on the type of radiation mode. The omnidirectional antenna has a peak gain of 0 to 2dBI; The gain of directional antenna can reach 6dbi. The gain affects the operating distance of the antenna. The first three types of antennas in the table below are linearly polarized, but microstrip antennas can make circular poles

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