RFID Tags

What is RFID tags made out of and its application areas

The main task of the label is to identify the main information of the product or commodity, and the recorded information is required to have high reliability and accuracy. It also requires the label itself to have low cost, better ease of use and data Durability. These application environments and conditions have promoted the development of modern electronic tags in the direction of flexibility, low cost, and high performance. At present, the electronic tags on the market can be divided into three kinds of substrates according to the material: paper material, flexible polyester film and hard plastic brand, etc. According to the antenna production process, they can be divided into wire-wound, aluminum film or copper film. Etching type, conductive silver paste printing type. Among them, the paper or polyester film etched electronic label with self-adhesive adhesive is the mature technology, strong durability and wide application; it is suitable for mass production and low-cost electronic labels, and its process uses silver paddle printing. Antenna and flip chip technology. They are widely used in cargo supply chain management, parcel and postal services, logistics warehousing management systems, libraries and rental services, aviation luggage labels, product certification, brand anti-counterfeiting protection, common identification systems, pressure vessel labels, etc. 

In addition, the design of the tag antenna and the further performance optimization after matching the chip must be adjusted repeatedly; the production process is also complicated, and each process must be strictly controlled to make the finished tag meet the design requirements and customer use needs. The typical electronic label production process of Newbega  Technology, which includes the following three main parts:

  1. Various raw materials-composite antenna substrate-antenna design drawing +Etching an antenna finished product
  2. Antenna finished product, placing IC chip, welding chip between layers, packaging, testing and counting, a core material finished product
  3. Core material finished product + pattern design + manufacturing Board + printing + double-sided tape-compound die cutting-test counting, etc.-finally get the finished electronic label.

The electronic tag is composed of a small chip (≤1mm) and a tag antenna of a moderate size. Take the paper label as an example. The base material of the antenna is composed of two layers of conductive aluminum film + one layer of insulating film + resin adhesive and then compounded to obtain the antenna core material. With the finished antenna, its non-contact chip can be mounted on the connection port of the antenna. The electrical connection between the chip and the antenna generally uses an ultrasonic IC bonding machine to bond with gold or aluminum wires, or use flip chip technology to communicate the circuit. The overall cost of the label produced by the metal film etching antenna and binding process may be higher than that of the label produced by the silver paste printing antenna and flip chip process, but the metal film antenna has an absolute advantage in terms of yield and durability.

The front side of the electronic label is generally printed with pictures and texts as required, usually pre-printed with flexible paper, and then the antenna and the printed layer/adhesive layer are glued, die-cut, and quality tested using an automated composite process. For example, to produce a self-adhesive paper color-printed electronic label, it generally requires 9 layers of base material to be compounded (release protective paper with double-sided adhesive layer), and the user tears off the bottom release paper. Stick the label firmly on the item to be marked.

The label size in actual application can be long, rectangular, round, etc. according to the conditions of use, and the plane size can also be large or small. Generally, the tag antenna is a frequency-limited device, which is only allowed to be used in a few narrow and different frequency bands. Considering the characteristic difference and gain requirements of the working frequency band, the antenna cannot be made too small. When the conditions of use permit, the effective area of ​​the electronic tag induction antenna should be as large as possible. Because the size of the electronic tag is too small, the sensing antenna must be smaller. At the same field strength, the electric energy induced by the small antenna is much weaker than that of the large antenna. Therefore, the reading distance of the tag of too small size may be relatively small. near. Generally speaking, the effective area of ​​the electronic tag antenna is preferably greater than 200mm. Above, otherwise the effective operation on the ordinary reading and writing equipment will become very difficult, and the tag information will not even be found. From the point of view of the working principle of the chip, only when the tag antenna receives a radio frequency signal with sufficient power due to the same frequency resonance induction, the charge pump located in the front end of the tag chip circuit may start to work, and can convert the part of the signal received and sent by the antenna into The DC voltage is used by the back-end circuit.

Contactless IC chip

In the HF band, there are many types of non-contact chips suitable for electronic tags. The following lists some commonly used IC chips that are more suitable for paper electronic tags, Mifare classic EV1 1K, Mifare classic EV1 4K, Mifare ultralight EV1, Ntag213 , Ntag215, Ntag216, Icode SLI-X for you to refer to.

 

UHF label production process and application

Compared with HF (high frequency) tags, UHF (ultra-high frequency) electronic tags have small size, long reading distance (1-15 meters), tag antenna structure, reading head RF power and reading head antenna gain), reading Advantages such as fast writing speed. Therefore, UHF electronic tags are the first choice for more and more RFID application projects. However, the working frequency of UHF electronic tags belongs to the decimeter waveband, and the reflection, refraction and penetration of the frequency are also relatively strong, and it has strict requirements on the directionality and article medium in actual use. For example, the reading distance of a label designed to work tightly on glass will become shorter when it is applied to a wooden board. Therefore, when ordering UHF tags, they must be customized according to the UHF chip model, application, environment and other factors actually used by the customer, and a better use effect will be obtained. UHF electronic label production process: A smart label is usually multi-layer composite of the following materials. The following takes the UHF electronic label produced by Newbega RFID Technology as an example to briefly explain the production process of the UHF electronic label:

  1. IC manufacturing: The semiconductor silicon material is processed and cut into wafers with a thickness of about 760μm, and then according to the designed circuit function, according to the order of production, under certain vacuum conditions, the wafers are subjected to multi-unit circuits ( 0.15μm) lithography evaporation, sputtering diffusion, injection etching, PVD, CVD, CMP mask and other process processing. And through physical means such as layer build-up, doping and heat treatment, using a variety of chemical substances (acids, alkalis, special gases and ionized water, etc.) to process multiple times, and finally form the required multilayer circuits and patterns on the semiconductor substrate. The process also needs to polish the back of the wafer (make the IC substrate thinner to suit the packaging of the IC card, usually with a thickness of 150 ~ 180 μm) and cutting, in order to obtain an independent unit circuit
  2. Antenna manufacturing: UHF electronic tags produced by Newbega RFID Technology currently mainly use conductive aluminum film to design, etch and optimize flexible antennas that meet the requirements. The purpose of optimization is to achieve the highest gain possible for the tag antenna within a limited area. Ensure that the antenna and card reader maintain good electrical performance and high transmission sensitivity
  3. Antenna base material: aluminum film is combined with PET or paper base to form an antenna body
  4. Chip connection: There are two ways, one is to use chip flip technology, using special strong directional conductive glue, to reliably flip the bump (protrusion, typical size Φ60~100um) on the chip on the aluminum film antenna ; Two: the use of welding technology, the use of ultrasonic IC welding machine and aluminum wire, gold wire to weld the antenna and the chip to form the RFID Inlay (core material)
  5. Surface material: The surface material of the label with a printing area to cover and protect the RFID Inlay and provide readable information
  6. Label substrate: Issuing substrate with release performance, used as the stereotype and protective bottom layer of electronic labels
  7. Gluing between layers: Adhesive for pasting Inlay on the label surface layer and the bottom layer of the setting

UHF label packaging: UHF label production process is directly from the flip-chip or binding of UHF integrated circuit chip → Inlay → finished label. There is also an important process in the middle, that is, it is possible to deliver In1ay to the required customers in the form of reel. In the process of automated label production line, it can be set to be able to handle the reel process form. The coiling process needs to carefully roll up the Inlay, and the quantity of each Inlay must be recorded at the same time during the quality inspection at the end of the assembly line to prevent damage to the core material during the coil packaging process, which is difficult in the Inlay production process.

In order to make the final RFID label, we usually use a variety of flexible packaging forms, such as RFID Inlay that contains a chip and an etched aluminum film antenna or is printed with graphics and text. After the electrical component can be tested, the Inlay is pasted on the adhesive contained on the back of the pressure-sensitive surface material. Use the same method to bond the Inlay to the substrate, and re-inspect and pack it in a tape-and-reel way, or be cut into a single label size, and then delivered to the customer in a box.

The following are several common UHF chips, which are suitable for clothing management, unmanned supermarkets, libraries, warehouse management, and logistics management, Ucode 8, Ucode7, Alien H3, Impinj M4QT,  for you to refer to.