Nanmao Technology introduces RFID technology to wafer test application (part 2)
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Implementation results of RFID introduction of wafer cassette tracking
Gate antennas are used at the entrance and exit of the warehouse and production line
Because the wafer cassettes are packed in cartons when they are transported in and out, there are two or one wafer cassettes packed into a carton and stacked on the pallet. Therefore, we need to find a pallet that can accommodate the width of the Nanmao pallet and reach the reading roll. The target antenna. According to the requirement of 120cm width of Nanmao stack board, we tested the German FEIG LR2000 RFID reader and antenna (Figure 4) and found that its effective reading distance can reach 160cm, so we set 140cm as the gate width (Figure 5) , On the one hand, it can take into account the RFID reading rate, on the other hand, it will not affect the original route planning of the equipment movement in the factory due to the erection of the gate antenna.
The LR2000 gate antenna is not composed of two antennas. In fact, it is an antenna group composed of two antennas on one side and four antennas on both sides. Through the antenna multi-task switch, it can achieve a large-scale reading function (Figure 6). At the same time, LR2000 The RF output power can be adjusted, depending on the use situation, from 4W to 10W as the interval, and every 0.25W is a section. The most important thing is that the LR2000 is equipped with an impedance matching circuit, which can detect the impedance matching of the RFID antenna in the field environment. As a result, the antenna impedance setting is then automatically adjusted to achieve impedance matching, so that the RF output can be fully functional without causing adverse effects.
The connection between LR2000 and the information system is through TCP/IP. In use, we stipulate that the RFID tag must be placed parallel to the antenna direction. When the stack plate is pushed between the gate antennas, it can be sensed and read. The test results are implemented. 24 wafer cassettes are packed into 12 cartons stacked together (3X2X2 , Figure 7) can be read completely.
At the same time, it needs to be considered that the location of the RFID label can meet all RFID application processes. Our experiment result is that it is attached to the inner tray of the wafer box (Figure 17). At the same time, the RFID tag will also store the wafer lot number and other in-plant quality control. Code required for the operation process.
Nitrogen tank RFID equipment
Because the nitrogen cabinet storing the 8-inch wafer cassette is entirely made of metal, I thought it would affect the reading rate at first, but later on, it improved the positioning accuracy by making good use of its nature, without interfering with each other, and without adding back-end software. The burden of the system. Because there are a total of four layers on the top and bottom of the nitrogen cabinet, each layer is divided into two compartments, so there are a total of eight sections, and each section can hold four wafer cassettes.
Here we use FEIG MR200 reader and antenna multi-task switch (Figure 9) and custom-sized antenna board. The operation method is to use an MR200 reader to connect to the antenna multi-task switch. This antenna multi-task switch The device can be used in one-to-eight groups or two-to-four groups. Because the nitrogen cabinet is divided into eight sections, the one-to-eight mode is naturally used. If there are more than eight, it can also be connected into a ladder tree extension. Range of use.
Figure 9. MR200 device and antenna multitask switcher
At the same time, because there is no public standard for nitrogen cabinets, they are all manufactured according to the requirements of the wafer yard. In the case of Nanmao, as mentioned above, there are four layers, eight sections, and four wafer cassettes in each section (Figures 12 and 13). Therefore, how to make every wafer box read is a problem we need to solve. Obviously, there is no ready-made antenna board on the market that can meet our size requirements, so we design the size specifications and entrust the hardware manufacturers to make customized Antenna board. After the installation of separate plates (Figure 10, 11), the antenna and the metal layer plate of the nitrogen cabinet have a certain distance to avoid the serious deformation of the magnetic field generated by the antenna and the inability to sense the RFID tag, but at the same time, the adjustment of the RF output power and the metal screen can be used. The label on the wafer cassette in other sections will not be sensed.
Figure 10. Customized antenna installation
Figure 11. Placement of wafer cassette
Figure 12, the compartment layer of the nitrogen tank
Figure 13. Appearance of the nitrogen tank
Trolley RFID device
When the wafer cassettes are in the trolley, the wafer cassettes cannot be overlapped by Nanmao. Therefore, when the trolley design is most commonly used in the Nanmao factory, a trolley can hold up to five wafer cassettes, which is more than the original RFID. In technology, one wafer and location are missing because of the need to place RFID readers, batteries, antenna distributors and other equipment. For the trolley application, we choose the MR200WiFi version. At the same time, in order to be able to read the wafer cassette label on the trolley outside, it is necessary to be able to determine where the trolley stops. First, we solve the problem of reading the wafer cassette on the trolley. We use an 80cmX60cm FEIG antenna, and fix the antenna on the side of the trolley (Figure 14) to facilitate the reading of the upper and lower wafer cassettes. The test The results can be read completely correctly.
Figure 14. Trolley antenna erection
In addition, it solves the problem of trolley positioning. According to Nanmao’s regulations, if trolleys are not in use, they must be parked in a marked parking area in accordance with the regulations. In this way, only the RFID tag needs to be attached to the trolley parking compartment (Figure 15). Corresponding codes are used to facilitate the query, so an antenna (Figure 16) needs to be installed under the trolley to facilitate the induction of RFID tags on the floor. In addition, because MR200 can only be connected to one set of antennas, we have installed an antenna splitter, so that MR200 can output two antennas at the same time, but it also causes the RF power received by each antenna to be halved. Fortunately, the test results will not affect the reading. Take function. Finally, install a rechargeable battery. Usually AC100V can be used. If you read it once a second, the battery can be used for nearly 80 hours. If you read it every 10 seconds, you can use it for up to a month. It also has an AC connector, which can be found at any time. Charge it after plugging.
Figure 15. Parking of the trolley 16. Reservation antenna under the trolley
Testing machine RFID equipment
In the original test operation, before the test operation, the operator needs to manually check the process window (this process window is the work flow list generated after the wafer cassette enters the Nanmao plant, and the wafer cassette is in the Nanmao plant All relevant information or inspection records of the operation process are recorded in this work order), after knowing the relevant parameters such as the wafer lot number to be tested, manually input the test system and download it to the designated test machine to perform the wafer test.
Therefore, when Nanmao introduces RFID technology, it can first replace the role of the work flow list. Through the RFID tag number, the related operation information of the wafer cassette can be stringed, and at the same time, it can be stored in the information system to reduce the cost of clean paper. In addition, instead of manually inputting the test wafer lot number parameters, the label information on the RFID induction wafer box is automatically input into the test system, and the test program is downloaded to reduce the problems caused by human error input. Here we use FEIG MR200 to connect the antenna board. The antenna board is fixed on the testing machine to carry the test wafer placement place (Figure 18, 19). When the test wafer is tested, the wafer is still placed in the wafer box. On the inner tray, the entire inner tray will be placed in the testing machine, so the RFID tag on the inner tray will be sensed to report wafer-related information to the test system.
Figure 18. Figure of RFID equipment on the test machine. 19. The wafer test entrance and antenna position of the test machine.
Import experience and organize
In recent years, RFID technology has continuously developed new technologies and applications. Therefore, people often have high expectations and imaginations for RFID technology. However, in the real application environment, the overcoming or processing of the physical characteristics and limits of RF is often RFID. The import manufacturer has always been difficult to smoothly handle the checkpoints; especially when the gap between the user and the helper in the mutual understanding, misunderstandings often occur.
Therefore, prior to the implementation of this case, according to the conditions required by the users, the Information Policy Committee will bring equipment to the site to conduct actual tests and verifications to judge and understand whether Nanmao’s needs are possible to be achieved, and at the same time through communication and coordination. Let Nanmao understand what RFID technology can achieve and what is impossible. The period lasted for as long as one year. At the same time, considering reducing the impact factors on the existing process modification, by formulating standard operating procedures to improve the stability of the RFID reading rate. Therefore, before a company wants to introduce RFID, its pre-assessment preparation must be very careful and clear. The following items can be used as reference:
Cost Expenses: At present, the cost of RFID is still unable to compete with barcodes. Therefore, importers must be able to correctly assess the relationship between expected results and cost expenditures. At the same time, in addition to the tangible costs of equipment procurement and construction, they also need to pay attention to intangible costs.
Reading rate requirements: Sometimes the low reading rate of RFID is not very discouraging. It is discouraging that the reading rate is close to 98%, 99% but still cannot be improved, or a large amount of cost is required to achieve a reading rate of 100 %, you need to consider whether you need to modify the operating process to avoid factors that affect the reading rate. The most important thing is to have a correct conceptual understanding of RF technology and not blindly believe in the advantages of non-contact sensing.
The impact of the operation process: the introduction of RFID technology will inevitably affect the process, so we must start with an independent process, or try to be the same as the original process, so that users can slowly adapt to the impact of RFID. There is a chance to fix it.
Plan goals correctly and maintain flexibility in the system: companies need to have complete planning goals for the introduction of RFID. What goals should be achieved in the short term (save time? Save manpower? Improve accuracy?) and what results should be achieved in the long run (partial implementation in the factory? Full site implementation (Implementation with upper and lower customers and manufacturers), the target needs to be determined before the introduction, so that each responsible unit can clearly understand their role; at the same time, the plan execution must maintain consistent flexibility and integration, so as to avoid the target Unable to achieve or waste or error in equipment planning, procurement, development, and maintenance.
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