Brief Introduction of RFID Printed Antenna Technology and Application Value
RFID (Radio Frequency IdenTIficaTIon) radio frequency identification technology has become the focus of attention of all countries. The basic components of the system include RFID electronic tags, RFID readers and antennas. Among them, the antenna is a device that receives or radiates the radio frequency signal power of the transceiver in the form of electromagnetic waves. In the RFID system, the antenna is divided into a tag antenna and a reader antenna. The goal of the tag antenna is to transmit the maximum energy into and out of the tag chip: when transmitting, the high-frequency current is converted into electromagnetic waves; when receiving, the electromagnetic wave is converted into a high-frequency current.RFID antennas have a variety of manufacturing processes. This article will summarize and analyze the production technology of RFID antennas, focusing on the latest production methods of RFID antennas, RFID printed antennas and related technologies, and look forward to its prospects.
Three RFID antenna fabrication technologies
RFID antenna manufacturing technology mainly includes etching method, coil winding method and printed antenna. Among them, the RFID conductive ink printed antenna is a new technology developed in recent years.
The above RFID tag antenna manufacturing methods are respectively applicable to RFID electronic tag products of different frequencies. The low-frequency RFID electronic tag antenna is basically made by winding. The high-frequency RFID electronic tag antenna can be realized by the above three methods, but the etched antenna is mainly used, and the material is generally aluminum or copper, and the UHF RFID electronic tag antenna is It is mainly based on printed antennas.
The etching method is also called a subtractive fabrication technique. The production process is as follows (taking a copper antenna as an example): firstly laminating a flat copper foil on a plastic film; then coating the copper foil with a photosensitive paste, drying it and passing a positive film (pattern with a desired shape) It is irradiated; it is placed in a chemical developing solution, at which time the illuminated portion of the photoresist is washed away to expose copper; finally, it is placed in an etching bath, and all copper not covered by the photoresist is etched away to obtain a desired shape. Copper coil.
Because of its high precision, the etched printed antenna can match the interrogation signal of the reader, and the impedance of the antenna and the RF performance applied to the object are good, but its only drawback is that the cost is too high.
When the RFID tag is manufactured by the coil winding method, the label coil is wound and fixed on a winding tool, and the number of turns of the antenna coil is required (typically 50-l500 ). This method is used for RFID tags with a frequency range of 125-134 KHz, which has the disadvantages of high cost and slow production speed.
The printed antenna directly prints conductive lines on the insulating substrate (film) with conductive ink to form an antenna and a circuit, which is also called an additive manufacturing technique. The main printing methods have been extended from screen printing to offset printing, flexographic printing, gravure printing, etc. The more mature production processes are screen printing and gravure printing. Advances in printing technology and its further application in the manufacture of RFID antennas have reduced the cost of RFID tag production, thereby facilitating the use of RFID tags.
The printed antenna itself has the following unique features compared to etched antennas and wound antennas:
First, the printed antenna manufacturing can more accurately adjust the electrical performance parameters to optimize the card performance.
The main technical parameters of RFID tags are: resonant frequency, Q value and impedance. In order to achieve optimal performance, all RFID tag manufacturing techniques can be obtained by changing the antenna number, antenna size and wire diameter. The printed antenna technology can also be precisely adjusted to a desired target value by locally changing the width of the line, changing the thickness of the wafer layer, and the like.
Second, the printed antenna manufacturing can arbitrarily change the shape of the coil to meet the user's surface processing requirements.
In response to the versatile use of RFID cards and the increasing variety of personalization requirements, printed antennas can be easily changed to any shape, such as surface surfaces of different curvatures and angles, to meet customer requirements without any reduction. Use performance.
Third, the printed antenna can use a variety of different card base materials.
Printed antennas can be used with different card materials according to user requirements. In addition to PVC (polyvinyl chloride), PET-G (copolyester), PET (polyester), ABS (acrylonitrile-butadiene-benzene) can also be used. Ethylene copolymer), PC (polycarbonate) and paper-based materials. If winding technology is used, it is difficult to produce RFID tags that are adapted to harsh environmental conditions using materials such as PCs.
Fourth, printed antenna manufacturing is suitable for wafer modules provided by various manufacturers.
With the widespread use of RFID tags, more and more IC chip manufacturers have joined the team that produces RFID chip modules. Due to the lack of uniform standards, the electrical performance parameters are different, and the flexibility of the printed antenna structure can be matched with different wafers and modules in different package formats to achieve the best performance.