RFID Tag Automatic Identification Technology

     RFID radio frequency identification is a non-contact automatic identification technology, which automatically identifies the target through the RF signal and obtain the relevant data, identify the work without human intervention, can work in a variety of harsh environments. RFID technology can identify high-speed moving objects and can simultaneously identify multiple electronic tags, quick and easy operation, frequent use in the supermarket.

RFID tags (by communication) are divided into passive, semi-passive (also known as semi-active), active three categories.


Passive tags do not have internal power supply. The internal integrated circuit is driven by the received electromagnetic waves, which are emitted by the RFID reader. When the tag receives a signal of sufficient strength, it can send data to the reader. This data includes not only the ID number (globally unique ID), but also data that is pre-existing in the EEPROM of the tag.

As passive tags have the advantages of low cost, small size, no power supply. The market's RFID tags are mainly passive.

Semi - active

In general, the passive tag antenna has two tasks, the first: to receive the electromagnetic wave emitted by the reader to drive the tag IC; second: the label back to the signal, you need to rely on the impedance of the antenna to switch to produce 0 With a change of 1. The problem is that if you want to have the best return efficiency, the antenna impedance must be designed in the "open circuit and short circuit", which will make the signal completely reflected, can not be tag IC receiver, semi-active label is to solve this problem. Semi-active similar to the passive, but it is more than a small battery, the power can drive the tag IC, making the IC in the working state. This advantage is that the antenna can not control the task of receiving electromagnetic waves, fully used as a return signal. Compared to passive, semi-active have a faster response speed, better efficiency.


Unlike passive and semi-passive, the active tag itself has an internal power supply to supply the power required by the internal IC to generate external signals. In general, active tags have a long read distance and a large memory capacity can be used to store some of the additional information sent by the reader.

Testing and measurement methods

As the adhesive in the actual use will be subject to a variety of stress test, we will be in the laboratory will be tested to ensure the quality of bonding. Common practice is to test the production of RFID equipment with production equipment. Chip positioning situation we can detect through the visual system, the performance of the label can be tested by the card reader system.

In addition to these production equipment comes with a quick test method, there are more detailed follow-up test method, used to test the quality of bonding.

Chip Shear Force: Use the shearing force test machine tool to push the chip away from the substrate. In shear testing, the ideal value for adhesive, chip and substrate adhesion should be no less than 25 N / mm2.

Adhesive Degree of Curing: DSC analysis (differential scanning calorimetry) can be used to detect whether the adhesive is fully cured within the selected parameter range. The test method can reflect the abnormal time due to the short curing time or the temperature is too low.

Micrographs: Micrographs of chips and substrates show the extent to which the chip and its bumps are pushed into the antenna. Insufficient pressure can lead to poor chip contact, too much pressure will lead to chip or substrate damage.

Determine the reading distance: In this test, keep the card reader power unchanged, the label will continue to stay away from the reader until the reader error. Or continue to increase the card reader power, until the label began to send data; in this case, the distance between the label and the reader has been set in advance.


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