1. Third, the handover area adjustment. After determining the students near the school, if the students around the school have basically reached the school's enrollment capacity and there are still students who are not enrolled, the transfer area between the schools will be adjusted, and these students may be allocated to a relatively distant school. Because students don't live particularly evenly, it is only possible to ensure that the vast majority of students are enrolled nearby, while a small number of students need to go to a school further awayGo to school.
2, what is the meaning of zoning the meaning of zoning the meaning of school district zoning refers to the county-level education administrative department under the guidance and coordination of the higher education administrative department, according to the number of school-age students, school distribution, school district, school size, traffic conditions and other factors. In accordance with the principle of nearby enrollment in accordance with the street, road section, house number, village group, etc., for each junior high school reasonably demarcate the counterpart primary school, pupils according to their primary school to enter the counterpart junior high school.
3, the division of school districts refers to the basic situation of the market population, social economy, employment location and existing schools based on the education department2 id=' Silicon Carbide wafer cutting method? '> Silicon carbide wafer cutting method? Silicon carbide (SiC) is a material with high hardness, so it is necessary to use appropriate cutting tools and methods in the cutting process. The following are some commonly used silicon carbide cutting methods: Diamond Wire Sawing: Diamond wire sawing is a common cutting tool that can be used to cut silicon carbide wafers. The diamond particles of the diamond wire saw can be cut on the hard surface of silicon carbide.
2, drilling method (Drilling Method: Drilling method is a traditional cutting method. First, drill a hole in the location where it needs to be cut, and then separate the ceramic out using methods such as mechanical or thermal stress. This method is suitable for some small size ceramic parts.
3, for the material with good solution, the laser half cutting technology first marks the material to a specific depth, and then uses the fragment technology to extend the cutting path, which simplifies the process and reduces the cost. In the GPP process, the combination of laser half cutting and split technology, as shown in Figure 5, plays an important role in the cutting of discrete device silicon wafersThe cutting effect is shown in Figure 7.
4, first put the silicon carbide chip on a flat grinding disk, use a diamond grinding wheel to rough grind the chip, and smooth the surface of the chip. This is followed by medium grinding with a finer powder until the desired accuracy is achieved. This usually requires multiple grinding and inspections to ensure the smoothness and flatness of the chip surface. Finally, a finer grinding or polishing powder is used for polishing to achieve the desired surface smoothness and quality.
5, the first high energy series solid laser, the product has a unique advantage in super semiconductor material processing, hard material processing, can be usedSilicon carbide wafer slicing, silicon wafer two-dimensional code marking, aluminum-based silicon carbide heat sink etching, diamond processing, precision cutting of aviation grade carbon fiber plate, etc. For the diamond processing industry can provide including diamond slicing processing, diamond seed core, diamond shape cutting (4P machine), diamond planning and other complete solutions.
6, surface cleaning: First of all, the silicon carbide wafer surface cleaning to remove surface pollutants and impurities. This can be done using solvent cleaning, ultrasonic cleaning, or other appropriate methods. Coarse grinding: Placing the wafer in a specific grinder, applying grinding particles (e.gAlumina) and grinding liquids (such as polymethyl methacrylate), which grind and level surfaces through rotation and motion interactions.
2, thinning: has been backed by gold (back silver) of the disc does not reduce the book. The non-gold (silver) round plate adopts coarse grinding and fine grindingMethod The original wafer was thinned; (2) Slice: According to packaging needs, choose ordinary blue Film, DAF (Die Attach Film) Film, CDAF (Co page 1 nductive Die Attach Film) film or UV (Ultra-viole-t Rays Film) film.
3, because the LED chip is still arranged closely after the slice is very small (about 0.1mm), it is not conducive to the operation of the post-process. We use a spreader to expand the film of the bonded chip, which is an LED chipThe spacing is stretched to about 0.6mm. Manual expansion can also be used, but it is easy to cause bad problems such as chip drop waste. LED dispensing Silver glue or insulating glue is placed on the corresponding position of the LED bracket.
4, the device or even the entire wafer cannot be used normally due to subsequent improper storage. Chip back silver peeling test is able to measure whether the metal layer is firm, is currently recognized as the most rapid, simple and effective method. To carry out the chip back silver peeling test, it is necessary to provide the fake sheet, the metal layer deposited on the back of the fake sheet, and determine the selected area of the metal layer to complete the experiment, so as to achieve the monitoringSolid, to meet the role of production needs.
5, the 0.65mm minimum bar distance of lead-tin welding is far from meeting the actual needs of conductive connections, and conductive silver glue can be made into slurry to achieve high line resolution. Moreover, the conductive silver adhesive process is simple and easy to operate, which can improve production efficiency and avoid environmental pollution caused by heavy metal lead in tin lead solder. Therefore, conductive silver glue is an ideal choice to replace lead tin welding and realize conductive connection.
6, M double-sided tape is also a double-sided tape with superior performance, it uses acrylic adhesive, so it has a high bonding strengthDegree and stickiness, can adapt to long-term temperature resistance and chemical resistance. However, the operation of this backing is more complex and takes a longer time to dry. Overall, Silverback double-sided tape performed better in terms of stickiness and durability, while 3M double-sided tape performed better in terms of bond strength and retention.
In the bright star of semiconductor equipment, the back-channel sealing equipment is like a bright pearl, driving the precision process of chip manufacturing. These installationsThe preparation covers packaging and testing two major links, and the key equipment in each link is constantly improved in precision and process innovation. Packaging equipment: precision is like a micron-level art, and the precision requirements of fine hair determine the yield and enterprise costs.
Welding machine: The welding machine is used to attach the chip to the packaging material. This device can be welded using hot pressing or ultrasonic welding. Fatigue tester: Fatigue tester is used to test whether the chip will fail after a long time of use. This device can simulate the stress and temperature environment in real use. Refrigerating machine: The refrigerating machine is used to cool the chip so thatGet more accurate results when testing.
Semiconductor packaging equipment generally have solder paste printing machine, solid crystal machine, reflow welding, light detection, repair equipment, etc., among which the most core is solid crystal machine, our company's production line is Zhuoxing Semiconductor solid crystal machine, very easy to use, the performance is very powerful.
Semiconductor production equipment: the core force driving the scientific and technological revolution Semiconductor special equipment plays a vital role in today's scientific and technological field, it is like the engine of the industry, promoting the vigorous development of the entire industrial chain. This sophisticated ecosystem can be divided into two main stages: front-end wafer manufacturingAnd after encapsulation test. Among them, the front path is based on the CZ method, and the single crystal growth furnace is like a lamp to illuminate the birth of the silicon wafer.
1, you mean how to cut the wafer when packaging? Before packaging, the chip will be thinned to about 200um, and then the wafer will be affixed to a blue film, and then sliced; After the loading process, the chip is separated from the blue film with a thimble and the chip is fixed to the package frame.
2, laser grooving and grinding wheel cuttingIn high-speed electronic components, laser grooving technology with grinding wheel cutting, low dielectric constant materials such as low k film processing is particularly clever. The laser slotting reduces the mechanical load to avoid film shedding, and the subsequent grinding wheel cutting ensures cutting quality and efficiency. This process is picturesque, as shown in Figure 1, and the cutting effect is clear, as shown in Figure 2.
3, separate the chip: the flow sheet will cut a number of chips from the wafer separated, so that each chip can be used separately. Increased productivity: With the flow sheet technology, the number of chips available on a single wafer can be significantly increased, thereby effectively improving production efficiencyRate and capacity. Testing and screening: In the flow sheet process, a series of testing and screening will be carried out on the cut chip to ensure that its quality and performance meet the requirements. 4, the charged ions are guided into the silicon crystal, so that the flow of electricity can be controlled, thereby creating the electronic switch of the basic building block of the chip - the transistor, which is ionization, also known as ion implantation. After the layer is ionized, the remaining photoresist used to protect the areas that are not etched is removed. To make a chip on a single wafer requires thousands of processes, from design to production takes more than three months.
6. Etching and ion implantation Etching removes exposed silicon oxide and silicon nitride and injects boron or phosphorus into the silicon structure to form a transistor. copper-fillThe circuit is easily connected and the photoresist is re-coated to build a multi-layer structure. A single chip typically contains dozens of layers of structure, similar to an interwoven highway. After completing the above steps, the silicon wafer is covered with chip patterns.