Packaging form of RFID tags suitable for containers

1. Introduction of electronic label packaging process

(1) Because the RFID tag chip is tiny and ultra-thin, the method used is flip chip (Flip Chip) technology. The automatic assembly line uses the production method from roll to roll. The process includes substrate feeding, gluing, and chip flipping Installation, hot press curing, testing, substrate collection and other processes. He has the characteristics of high performance, low cost, miniaturization and high reliability. However, the process equipment is expensive and generally requires equipment from foreign manufacturers.

(2) Another packaging method is to divide the bonding package of the chip and the antenna substrate into two modules. One specific method (Chinese patent) is: large-sized antenna substrates and small substrates connected to the chips are manufactured separately. After chip mounting and interconnection are completed on the small substrates, the large-size antenna substrates are passed through the large pads. The adhesion completes the circuit conduction. In this method, the chip module is placed on the carrier tape by an independent and precisely positionable chip transfer device, and then the chip module is transferred to the antenna substrate. The advantage is that the two transfers can be performed independently and in parallel.

At present, the flip-chip technology is a relatively mature label packaging technology. This packaging technology has the advantages of simple packaging procedure, mature process, low cost, small size, ultra-thin packaging and easy sticking. Most of the common labels on the market also use this process. However, this kind of equipment is expensive, and there are very few manufacturers that can carry out flipping in China. Most of them adopt the second method, which precisely welds the chip and the antenna to achieve the purpose of connection. Compared with the first one, this technology has much lower equipment requirements, but the packaging process takes a long time.

2. Discussion on the packaging technology suitable for electronic tags for containers

In practical applications, the packaging size and form of most labels are limited by the objects attached to the labels. Generally, the labels are small and thin, and can be repackaged into cards. The surface area of the container is very large, which relaxes the requirements on the surface area and volume of the label. This is very advantageous for the design of the tag antenna. Because in many cases, the volume of the marked object requires the volume of the tag to be small, and its sensing antenna must be small. In the same field strength, the electric energy induced by the small antenna is much weaker than the large antenna. The reading distance required for the dynamic reading of electronic tags for containers is relatively long (approximately 10 m), so the requirements for the antenna size are higher because the smaller antennas show higher field strength when they are close to the reader However, the field strength of larger antennas at higher distances is still higher [4]. Therefore, the electronic label for the container can be made larger, and finally packaged in a box shape and fixed on the surface of the container. There is no need to make it flexible, paper-made, or adhesive.

According to the actual needs of the electronic label to identify the container, the paper label made by the flip-chip process cannot meet the requirements of anti-vibration and anti-corrosion in the working environment of the container, and the volume of the label package does not need to be very thin. Horizontally, the chip can be TSSOP packaged before the chip and the antenna are soldered, and lead out the required pins. Based on this, the Chinese patented technology is used to realize the interconnection of the chip and the antenna. In this process, the chip package and the antenna substrate bonding package are divided into two modules to complete. Then, the medium is filled and the shell is sealed, and finally the finished container electronic label is finished, and high temperature aging, testing and packaging are carried out. In this process, the requirements of the use environment on the metal surface reflection, waterproof, moisture, fog, lightning and other indicators are considered.

After TSSOP packaging the chip, the pins are bonded to the antenna to solve the problem of expensive packaging equipment and dependence on foreign technology. And compared with the previous two types of packaging labels, TSSOP packaging materials have the characteristics of compression and high temperature resistance, which can meet the higher requirements of the container working environment and improve the reliability and stability of the label. Compared with the flexible packaging, the entire label packaging has a medium filling, which solves the problem of the effect of the container metal on the label. The sealed casing can meet the requirements of various aspects such as large temperature difference, high humidity, strong corrosion of acid and alkali and salt spray, and large vibration and shock.

Conclusion

At present, China's radio frequency identification technology is still in its infancy, and the application of RFID technology to the container industry has very optimistic prospects. However, the application of electronic tags in the container industry is very special. Through research, this paper expounds many issues that should be considered in antenna design and impedance matching in the case of metal surface interference, points out his design direction, shows that the packaging of electronic tags can break through the traditional electronic tag packaging form, and choose a suitable The packaging of the application environment of the container solves the problem of metal surface interference by filling the dielectric material. With the maturity of the electronic tag technology, his application field will continue to expand. In the near future, the container vehicle driving can tell the traffic management system its specific location. When a fully loaded freight train passes by, the roadside sensor will show The type and quantity of goods loaded in the car, etc.