Manufacturing Technology of RFID Antenna and Prospect Analysis of RFID Printing Antenna

With the rapid development of the Internet of Things, more and more applications of RFID technology have been applied in logistics, retail, warehousing, books, archives and other fields. Therefore, RFID technology also needs continuous improvement to adapt to the application requirements of different industries and fields. Using conductive ink and advanced RFID Antenna printing technology can optimize the application value of RFID electronic tags and further promote the application of RFID.

In the RFID system, the antenna is divided into two types: tag antenna and reader antenna. The goal of the tag antenna is to transfer the maximum amount of energy into and out of the tag chip: when transmitting, convert current into electromagnetic waves; when receiving, convert electromagnetic waves into current.

RFID Antenna Manufacturing Technology

RFID antenna manufacturing technology is mainly divided into three types: coil winding method, etching method and printed antenna. Among them, RFID conductive ink printing 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. The high-frequency RFID electronic tag antenna can be realized by the above three methods, but the etching antenna is the main material, and its material is generally aluminum or copper. The UHF RFID electronic tag antenna is Mainly printed antennas.

(1) Coil winding method

The coil winding method needs to wind the label coil on a winding Tool and fix it. At this time, the number of turns of the antenna coil is required to be large (typically 50-1500 turns). This method is used for RFID tags in the frequency range of 125-134 KHz, and its disadvantages are high cost and slow production speed.

(2) Etching method

The etching method starts by laminating a flat copper foil on a plastic film; then coating the copper foil with a photosensitive adhesive, drying it and exposing it to light through a positive film (with a pattern of the desired shape); placing it in a chemical developer At this time, the illuminated part of the photosensitive adhesive is washed away to expose the copper; finally put into the etching pool, all the copper not covered by the photosensitive adhesive is etched away, so as to obtain the copper coil of the desired shape. The antenna made by the etching method has high precision, and its characteristics can match the interrogation signal of the RFID Reader. At the same time, the impedance and radio frequency performance of the antenna are very good, but the cost is too high.

(3) Printed antenna

Printed antennas are printed conductive lines directly on insulating substrates (films) with conductive ink to form antennas and circuits. Its main printing method has been expanded from screen printing only to offset printing, flexographic printing, gravure printing and other production methods and developed into a relatively mature screen printing and gravure printing technology.

What are the advantages of RFID printed antennas?

1. No pollution

The photosensitive glue and other chemical reagents that must be used in the copper etching process have a strong erosive effect, and the waste and discharge produced will cause greater pollution to the environment. However, the conductive ink is used to print directly on the substrate without using chemical reagents, so it has the advantage of no pollution.

2. Good electrical conductivity

After the conductive ink is dried, since the distance between the conductive particles becomes smaller, the free electrons move along the direction of the applied electric field to form a current, so the RFID printed antenna has good conductivity.

3. Easy to operate

As an additive manufacturing technology, printing technology itself is an easy-to-control, one-step process compared with subtractive manufacturing technologies (such as etching).

4. The choice of base material is flexible and diverse

Conductive ink can be printed on almost all printing materials, including polyester, polyimide, ABS Engineering plastics, PVC (polyvinyl chloride), polyethylene, polypropylene, polycarbonate, (coating) cardboard, etc. Copper etching technology can only use highly corrosion-resistant substrates such as polyester, which are generally more expensive than the substrates selected for printing.

The printed conductive ink antenna is also able to withstand higher external mechanical stress. In addition, the RFID label printing antenna made of conductive ink has better elasticity and higher reliability.

5. Low cost

The cost reduction of RFID printing antenna mainly depends on the two reasons of conductive ink material and screen printing process. In terms of the cost of the material itself, the price of ink is lower than that of stamping or etching metal coils, especially in the case of rising copper and silver prices, using conductive ink printing to make RFID antennas is an ideal alternative method; from In terms of material consumption, etching consumes a lot of metal, while conductive ink printing antenna circuits are fast, material-saving, low-cost, and high-efficiency.

One of the reasons why the screen printing process can reduce costs is that the investment in the introduction of printing equipment is much cheaper than the introduction of copper etching equipment. In addition, since there is no need to add additional investment due to environmental protection requirements in the printing process, the maintenance cost of production and equipment is also lower than that of copper etching, thereby reducing the unit cost of the label.

When printing RFID antennas with conductive ink, special attention should be paid to the following aspects to achieve the best printing effect.

Pre-treatment: To ensure that the printing surface is clean and free of pollution, grease and oxides, etc., the shorter the stay time after the printing surface treatment, the better to prevent oxidation or pollution.

Operating environment: The choice of printing environment has a direct impact on the printing effect. The dust and foreign matter pollution in the printing area should be minimized. The environmental requirement is at least a clean room above 100,000.

Dilution: After adjusting the viscosity of the ink, adding a small amount of thinner can improve the printing effect of automatic printing. Stir well for 10 minutes before use.

Pre-drying: The temperature and time can be adjusted according to the specific production process.

Storage: Store at a temperature of 20-25 degrees, away from light and heat.

It can be seen that the use of conductive ink to make RFID printing antennas has high requirements for technology. For the conductive ink itself, it should have the characteristics of strong adhesion, low resistivity, low curing temperature, and stable conductivity, so as to meet the functional requirements of the RFID antenna.

Of course, the reason why RFID printed antennas are stronger than traditional antennas mainly depends on the characteristics of conductive ink and its perfect combination with printing technology.

Conductive ink is composed of fine conductive particles or other special materials (such as conductive polymers, etc.), which can be printed on flexible or hard substrates to make printed circuits, which act as wires, antennas and resistors. The conductive ink largely determines the impedance of the RFID printed antenna, an important parameter related to the performance of the RFID antenna.