RFID tag antenna manufacturing technology

Currently, there are three antenna manufacturing technologies: etched / punched antenna, printed antenna and printed antenna. Among them, the winding and printing technology has been widely used in mainland China, and most RFID tag manufacturers in Taiwan also use this technology; and the etching technology is mainly used in Europe, while in Taiwan, there are only a few flexible circuit boards The factory has the ability to use this technology to manufacture RFID tags. The winding technology can only be used to manufacture 125K and 13.56M bandwidth RFID tags, and cannot be used to manufacture UHF bandwidth RFID tags. Both printing technology and etching technology can be applied to mass manufacturing 13.56M, UHF bandwidth, but the quality of printing is worse than etching and the durability is shorter. The durability of printed RFID tags is generally two to three years. However, the etched RFID tags are durable for more than ten years.

According to the requirements of the US passport case (e-passport), the basic requirement of the tag's durability is more than ten years, and it must be manufactured by etching technology. The following briefly introduces the characteristics and differences of the two technologies of winding and printing.

1. Structure and characteristics of printed antenna

The significant difference between RFID tags (also known as contactless IC cards) and other card products such as contact IC cards is that they include an INLAY layer containing an antenna and a chip. Different INLAY manufacturing methods form unique manufacturing technologies. Different manufacturing technologies also affect the structural design of RFID tags. A printed layer and a protective film are added to both sides of an INLAY to form an RFID tag.

Compared with wire-wound antennas, printed antennas have the following advantages:

(1) The manufacture of printed antennas can adjust the electrical performance parameters more accurately, and optimize the performance of the card. The design of electrical performance parameters of RFID tags is very important, which directly affects the adaptability and working stability of the reading distance of RFID tags to the card reader. The main technical electrical properties of RFID tags are: resonance frequency, Q value and impedance. In order to achieve optimal performance, all RFID tag manufacturing technologies can be obtained by changing the number of antenna turns, antenna size, and wire diameter. However, in addition to the printed antenna technology, it is also possible to accurately adjust to the desired target value by locally changing the width of the line and the thickness of the wafer layer. The resonance frequency, Q value and impedance of the RFID tag can be measured using an impedance meter or a network analyzer.

(2) The manufacture of printed antennas can change the shape of the coil arbitrarily to suit the user's surface processing requirements. Due to the multi-purpose use of RFID cards and the increasing requirements for various personalization, there will be various restrictions on the surface of the RFID tag and the card body, such as embossing and sensitive graphics. The printed antenna INLAY can be easily changed to any shape as required, or even an irregular curve to meet customer requirements without reducing any performance.

(3) A variety of different card base materials can be used for the manufacture of printed antennas. This structure can use different card base materials according to user requirements. In addition to PVC, PET-G, PET, ABS, PC and paper-based materials can also be used. . If winding technology is used, it is difficult to produce RFID tags that adapt to harsh environmental conditions using materials such as PCs.

(4) Printed antenna manufacturing is suitable for wafer modules provided by various manufacturers. With the widespread use of RFID tags, more and more IC wafer manufacturers have joined the production team of RFID wafer modules. Due to the lack of a unified standard, the electrical performance parameters are also different, and the flexibility of the INLAY structure of the printed antenna can be matched with a variety of different chips and modules with different packaging forms to achieve the best performance.

2. Antenna printing technology

Antenna printing is an important process.

The antenna printing technology is the same as the general screen printing technology. First, make a plate according to the designed antenna shape. Printed mesh can be 100-257 mesh /? Jia? 溲 ∮ 谩 S∷⒂Turn? Difficult ∮ Lemon? Stop ,? S 氎 鰟 turb? 宑 翣 濉 STurn? Gourmet? Unqualified wall Reel? Spit love to take R? ∮mei cut ┑ steal the province ⒑ Shao Dang que bang turbulent? S :: ⒑ Sheng Xia Φ 缱 漰 詍 between -25Ω.

According to the actual technical requirements, using single-sided or double-sided printed antennas can obtain the required inductance. To obtain a high-quality antenna, it needs to be improved beyond many subtleties, such as ink selection, ink blending, pressure size, mesh selection, etc., printing plate production and ink drying. These all require long-term practical experience accumulation. Compared with wire-wound and etched antennas, the most significant feature of the printed antenna technology is less investment and high efficiency.

3. Connection technology between chip module and antenna

Connection refers to the connection between the chip module and the antenna. It is a key link in all different antenna manufacturing technologies. The printed antenna and the module are generally bonded by conductive adhesive or directly pressed. The overlapping area of ​​the printed antenna is generally larger than the area of ​​the connection end of the module, which ensures the reliability of the connection. Coupled with the high temperature and high pressure during lamination, the module lead end and the antenna tower connection block are melted into one. The advantages of this connection method are high technical operability and high performance reliability.

The wire-wound antenna is usually connected to the module by welding. This kind of technology can ensure a good connection under the conditions of reliable welding, rigid antenna and very accurate module position, and good welding current control. However, due to many controlled factors, defects such as virtual welding, false welding and partial welding are prone to occur. Another advantage of this connection method is that it can use small modules, such as Mifare1, FCP2 modules, etc., for easy connection without reducing the production capacity and increasing the cost. With such small package modules, RFID tags with a thickness of 0.5mm can be produced without any trace on the surface. The RFID tag manufacturing industry now has the technology of bonding wafers (Die) and printed antennas, and is widely used in the production of smart tags.