“RFID (Radio Frequency IdenTIficaTIon) radio frequency identification technology has now become the focus of attention of all countries. The basic components of its 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 radio transceiver in the form of electromagnetic waves. In the RFID system, antennas are divided into tag antennas and reader antennas. The goal of the tag antenna is to transmit the maximum energy in and out of the tag chip: when transmitting, it converts high-frequency current into electromagnetic waves; when receiving, it converts electromagnetic waves into high-frequency current.
RFID (Radio Frequency IdenTIficaTIon) radio frequency identification technology has now become the focus of attention of all countries. The basic components of its 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 radio transceiver in the form of electromagnetic waves. In the RFID system, antennas are divided into tag antennas and reader antennas. The goal of the tag antenna is to transmit the maximum energy in and out of the tag chip: when transmitting, it converts high-frequency current into electromagnetic waves; when receiving, it converts electromagnetic waves into high-frequency current.
There are many manufacturing processes for RFID antennas. This article will summarize and analyze the manufacturing technology of RFID antennas, focusing on the latest manufacturing method of RFID antennas-RFID printed antennas and related technologies, and look forward to its prospects.
Three kinds of RFID antenna production technology
RFID antenna manufacturing technology mainly includes three kinds of etching method, coil winding method and printed antenna. Among them, RFID conductive ink printed antenna is a new technology developed in recent years.
The above manufacturing methods of RFID tag antennas are respectively applicable to RFID electronic tag products of different frequencies. The low-frequency RFID electronic tag antenna is basically made by winding method. The high-frequency RFID electronic tag antenna can be realized by the above three methods, but the antenna is mainly etched. The material is generally aluminum or copper, while the UHF RFID electronic tag antenna is Mainly with printed antennas.
The etching method is also called a subtractive manufacturing technique. The production process is as follows (take a copper antenna as an example): First, a flat copper foil is laminated on a plastic film; then photosensitive glue is coated on the copper foil, and after drying, a positive film (pattern with the desired shape) is used to pair It is irradiated; put into a chemical developer, the light part of the photosensitive glue is washed away at this time, exposing the copper; finally put into the etching bath, all the copper that is not covered by the photosensitive glue is etched away, so as to obtain the desired shape Copper coil.
The etched printed antenna has high accuracy and characteristics that can match the interrogation signal of the reader. At the same time, the impedance of the antenna and the radio frequency performance applied to the article are very good, but its only disadvantage is that the cost is too high.
When using the coil winding method to make RFID tags, the tag coil must be wound and fixed on a winding tool. At this time, the number of turns of the antenna coil is required to be large (typically 50-l500 turns). This method is used for RFID tags with a frequency range of 125-134 KHz. Its disadvantages are high cost and slow production speed.
Printed antenna is to directly use conductive ink to print conductive lines on an insulating substrate (film) to form antennas and circuits, which is also called additive manufacturing technology. The main printing methods have expanded from only screen printing to offset printing, flexographic printing, gravure printing and other production methods. The more mature production processes are screen printing and gravure printing. The advancement of printing technology and its further application in the production of RFID antennas have reduced the production cost of RFID tags, thereby promoting the application of RFID electronic tags.
Compared with the etched antenna and the coiled antenna, the printed antenna itself has the following unique features:
1. Printed antenna manufacturing can adjust the electrical performance parameters more accurately, optimizing the performance of the card.
The main technical parameters 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. The printed antenna technology can also be precisely adjusted to the required target value by locally changing the width of the line, changing the thickness of the wafer layer, and so on.
2. The shape of the coil can be arbitrarily changed in the manufacture of printed antennas to meet the user’s surface processing requirements.
In view of the multi-purpose use of RFID cards and the increasing requirements of various personalizations, the printed antenna can be easily changed into any shape according to the requirements, such as object surfaces with different curvatures and angles, to meet customer requirements without reducing any Use performance.
3. The printed antenna can use a variety of different card base materials.
Printed antennas can use different card body 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 use materials such as PC to produce RFID tags that can adapt to harsh environmental conditions.
4. Printed antenna manufacturing is suitable for chip modules provided by various manufacturers.
With the widespread use of RFID tags, more and more IC chip manufacturers have joined the ranks of producing RFID chip modules. Due to the lack of a unified standard, the electrical performance parameters are also different, and the flexibility of the printed antenna structure can be matched with a variety of different chips and modules in different packaging forms to achieve the best performance.