Electronic-grade polycrystalline silicon conveying system

Abstract

The utility model discloses an electronic-grade polycrystalline silicon conveying system, which relates to the technical field of polycrystalline silicon production, and comprises a material input unit, a pneumatic diaphragm pump and a heater, an input port of the material input unit is connected to a heating inlet of the heater, and a heating outlet of the heater is connected with an inlet unit of the pneumatic diaphragm pump; a first outlet unit of the pneumatic diaphragm pump is configured to output a target material; the diaphragm assembly of the pneumatic diaphragm pump is made of PTFE. The electronic-grade polycrystalline silicon conveying system provided by the utility model can realize a simple, efficient, low-cost, clean and energy-saving conveying system for the electronic-grade polycrystalline silicon.

Description

Technical Field

[0001] The present application relates to the technical field of polysilicon production, and in particular to an electronic-grade polysilicon delivery system. Background Art

[0002] At present, electronic-grade polysilicon is one of the most basic and important raw materials for manufacturing semiconductor silicon wafers. Among them, the purity of electronic-grade polysilicon must reach 11N. Such a high purity places extremely high demands on equipment material selection, process stability control, detection technology and quality management. In order to improve the quality of electronic-grade polysilicon materials, the electronic-grade polysilicon conveying system needs to operate stably and reduce impurities in the electronic-grade polysilicon conveying system during operation, so as to ensure the quality of the materials conveyed by the electronic-grade polysilicon system and achieve the purpose of energy saving and environmental protection.

[0003] However, in the related art, the power source in the electronic-grade polysilicon delivery system is a carbon steel centrifugal pump, which will bring in impurities during operation. For example, carbon steel centrifugal pumps usually use mechanical seals as shaft seals. Due to the requirements of the working environment and the aging of the equipment, the sealing performance of the mechanical seal may decline, resulting in material leakage. This leakage will not only cause waste of materials, but also allow external impurities to enter the pump body, thereby affecting the purity of electronic-grade polysilicon and the materials in the electronic-grade polysilicon delivery system. For another example, the carbon steel material itself contains certain impurities, such as rust, oxides, etc. During the operation of the carbon steel centrifugal pump, these impurities may be transported into the system along with the materials, thereby causing pollution to the electronic-grade polysilicon and the materials in the electronic-grade polysilicon delivery system. For another example, the carbon steel material will react with some chemical materials, thereby affecting the purity of the output materials in the electronic-grade polysilicon delivery system.

[0004] Therefore, there is an urgent need to propose an electronic-grade polysilicon delivery system that can meet the requirements of a simple, efficient, low-cost, clean and energy-saving delivery system for electronic-grade polysilicon. Summary of the invention

[0005] The present application proposes an electronic-grade polysilicon delivery system, which can realize a simple, efficient, low-cost, clean and energy-saving delivery system that meets the requirements of electronic-grade polysilicon.

[0006] In an embodiment of the present application, the electronic-grade polysilicon delivery system includes: a material input unit, a pneumatic diaphragm pump, and a heater;

[0007] The input port of the material input unit is connected to the heating inlet of the heater, and the heating outlet of the heater is connected to the inlet unit of the pneumatic diaphragm pump; the first outlet unit of the pneumatic diaphragm pump is configured to output the target material;

[0008] Wherein, the material of the diaphragm assembly of the pneumatic diaphragm pump includes PTFE.

[0009] In an embodiment of the present application, the material input unit includes a first material input unit, a second material input unit and a third material input unit;

[0010] The first material input unit is configured to input chlorosilane material into the heater;

[0011] The second material input unit comprises a nitrogen input unit, a nitrogen purification unit and a heat exchanger connected in sequence, and the second material input unit is configured to input the heat-exchanged nitrogen into the heater;

[0012] The third material input unit is configured to input steam condensate into the heat exchanger.

[0013] In an embodiment of the present application, the nitrogen input unit is configured to input nitrogen into the nitrogen purification unit;

[0014] The nitrogen purification unit is configured to purify the nitrogen and input the purified nitrogen into the heat exchanger;

[0015] The heat exchanger is configured to perform heat exchange between the received steam condensate and the purified nitrogen to obtain the heat-exchanged nitrogen;

[0016] The heater is configured to heat the heat-exchanged nitrogen according to heating conditions to obtain driving nitrogen, and input the driving nitrogen into the pneumatic diaphragm pump to drive the pneumatic diaphragm pump to work.

[0017] In the embodiment of the present application, the condensate pipe, the coil, and the drying chamber;

[0018] The condensate pipe has an input pipe opening and an output pipe opening;

[0019] The input pipe opening of the condensate pipe is configured to input steam condensate into the heat exchanger; the output pipe opening of the condensate pipe is configured to be coupled with the coil by pipe;

[0020] The coil is spirally arranged on the drying bin;

[0021] The drying chamber comprises a drying inlet, and the drying inlet is configured to receive the nitrogen tail gas output by the second output unit of the pneumatic diaphragm pump;

[0022] Industrial silicon powder is arranged in the drying chamber, and the drying chamber is configured to utilize the nitrogen exhaust gas to heat and dry the industrial silicon powder.

[0023] In an embodiment of the present application, the heating condition includes: when the temperature of the nitrogen after heat exchange is greater than or equal to 5° C., stopping heating the nitrogen after heat exchange.

[0024] In an embodiment of the present application, the output target material includes chlorosilane.

[0025] In an embodiment of the present application, the system further includes: a filter, which is disposed on the drying bin and connected to the drying bin; the filter is configured to filter moisture from the industrial silicon powder in the drying bin.

[0026] In an embodiment of the present application, the heater includes electric heating.

[0027] In an embodiment of the present application, the system further includes: an emptying system, and the emptying system is connected to the filter through a pipeline.

[0028] In an embodiment of the present application, the pneumatic diaphragm pump further includes: a cavity; the diaphragm assembly is disposed in the cavity, and the material of the cavity includes: PTFE.

[0029] The electronic-grade polysilicon conveying system provided in the present application uses a pneumatic diaphragm pump to convey materials. The pneumatic diaphragm pump uses a diaphragm assembly to completely separate the cavity from the drive assembly. This arrangement prevents the material in the pneumatic diaphragm pump from directly contacting the drive assembly of the pneumatic diaphragm pump, thereby reducing impurities generated by wear of the drive assembly.

[0030] At the same time, the sealing performance of the diaphragm assembly also ensures that the material will not leak into the external environment during transportation, further reducing the possibility of impurity contamination.

[0031] In an embodiment of the present application, the diaphragm assembly of the pneumatic diaphragm pump is made of corrosion-resistant and wear-resistant PTFE material. These PTFE materials can resist corrosion and wear of the conveyed materials, thereby extending the service life of the pneumatic diaphragm pump and reducing the generation of impurities.

[0032] In addition, the flow rate of the pneumatic diaphragm pump can be adjusted steplessly by adjusting the air source pressure, so that the pneumatic diaphragm pump can maintain a stable flow rate and pressure output when handling liquids of different viscosities and containing solid particles. Among them, this stability of the pneumatic diaphragm pump helps to reduce impurities caused by flow fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0034] Figure 1A schematic diagram of the structure of an electronic-grade polysilicon delivery system provided in an embodiment of the present application.

[0035] Description of labels:

[0036] 1. Material input unit, 2. First material input unit, 3. Second material input unit, 4. Third material input unit, 5. Nitrogen input unit, 6. Nitrogen purification unit, 7. Heat exchanger, 8. Heater, 9. First heater, 10. Second heater, 11. Condensate pipe, 12. Pneumatic diaphragm pump, 13. First outlet unit, 14. Second outlet unit, 15. Output material unit, 16. Filter, 17. Emptying unit, 18. Coil, 19. Drying bin, 20. Steam condensate unit. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0038] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present application.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0040] In this application, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] At present, electronic-grade polysilicon is one of the most basic and important raw materials for manufacturing semiconductor silicon wafers. Among them, the purity of electronic-grade polysilicon must reach 11N. Such a high purity places extremely high demands on equipment material selection, process stability control, detection technology and quality management. In order to improve the quality of electronic-grade polysilicon materials, the electronic-grade polysilicon conveying system needs to operate stably and reduce impurities in the electronic-grade polysilicon conveying system during operation, so as to ensure the quality of the materials conveyed by the electronic-grade polysilicon system and achieve the purpose of energy saving and environmental protection.

[0043] In the related art, the power source in the electronic-grade polysilicon delivery system is a carbon steel centrifugal pump. However, the carbon steel centrifugal pump will bring in impurities during operation. For example, carbon steel centrifugal pumps usually use mechanical seals as shaft seals. Due to the requirements of the working environment and the aging of the equipment, the sealing performance of the mechanical seal may decline, resulting in material leakage. This leakage will not only cause waste of materials, but also allow external impurities to enter the pump body, thereby affecting the purity of electronic-grade polysilicon and the materials in the electronic-grade polysilicon delivery system. For another example, the carbon steel material itself contains certain impurities, such as rust, oxides, etc. During the operation of the carbon steel centrifugal pump, these impurities may be transported into the system along with the materials, thereby causing pollution to the electronic-grade polysilicon and the materials in the electronic-grade polysilicon delivery system. For another example, the carbon steel material will react with some chemical materials, thereby affecting the purity of the materials in the electronic-grade polysilicon delivery system.

[0044] Figure 1A schematic diagram of the structure of an electronic-grade polysilicon delivery system provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the electronic-grade polysilicon delivery system can realize a simple, efficient, low-cost, clean and energy-saving delivery system for electronic-grade polysilicon.

[0045] In the embodiment of the present application, the electronic grade polysilicon delivery system includes: a material input unit 1, a pneumatic diaphragm pump 12, and a heater 8. The input port of the material input unit 1 is connected to the heating inlet of the heater 8, the heating outlet of the heater 8 is connected to the inlet unit of the pneumatic diaphragm pump 12, and the first outlet unit 13 of the pneumatic diaphragm pump 12 is configured to output the target material. The material of the diaphragm assembly (not shown) of the pneumatic diaphragm pump 12 includes PTFE.

[0046] It should be noted that the diaphragm assembly is a key component in the pneumatic diaphragm pump. The diaphragm assembly reciprocates with the drive of the gas, thereby changing the cavity volume of the pneumatic diaphragm pump, thereby realizing the transportation of materials.

[0047] Furthermore, PTFE (polytetrafluoroethylene) is a high-performance plastic material with excellent corrosion resistance, high temperature resistance and wear resistance. Using PTFE as the material of the diaphragm assembly can significantly improve the corrosion resistance of the pneumatic diaphragm pump, enabling it to transport more complex materials while reducing impurities caused by material corrosion.

[0048] The electronic-grade polysilicon conveying system provided in the present application uses a pneumatic diaphragm pump 12 to convey materials. The pneumatic diaphragm pump 12 uses a diaphragm assembly to completely separate the cavity from the drive assembly. This arrangement prevents the material in the pneumatic diaphragm pump 12 from directly contacting the drive assembly of the pneumatic diaphragm pump 12, thereby reducing impurities generated by wear of the drive assembly.

[0049] At the same time, the sealing performance of the diaphragm assembly also ensures that the material will not leak into the external environment during transportation, further reducing the possibility of impurity contamination.

[0050] In the embodiment of the present application, the diaphragm assembly of the pneumatic diaphragm pump 12 is made of corrosion-resistant and wear-resistant PTFE material. These PTFE materials can resist corrosion and wear of the conveyed materials, thereby extending the service life of the pneumatic diaphragm pump and reducing the generation of impurities.

[0051] In addition, the flow rate of the pneumatic diaphragm pump 12 can be adjusted steplessly by adjusting the air source pressure, so that the pneumatic diaphragm pump 12 can maintain a stable flow rate and pressure output when processing liquids with different viscosities and containing solid particles. Among them, the stability of the pneumatic diaphragm pump 12 helps to reduce impurities generated by flow fluctuations.

[0052] In the embodiment of the present application, the material input unit 1 includes a first material input unit 2, a second material input unit 3 and a third material input unit 4. The first material input unit 2 is configured to input chlorosilane material to the heater 8. Furthermore, the heater 8 includes electric heating.

[0053] The second material input unit 3 includes a nitrogen input unit 5 , a nitrogen purification unit 6 and a heat exchanger 7 which are connected in sequence, and the second material input unit 3 is configured to input the heat-exchanged nitrogen into the heater 8 .

[0054] The third material input unit 4 is configured to input steam condensate into the heat exchanger 7 .

[0055] Furthermore, the heater 8 includes: a first heater 9 and a second heater 10 , and the first material input unit 2 is connected to the pneumatic diaphragm pump 12 via the first heater 9 ; the second material input unit 3 and the third material input unit 4 are connected to the pneumatic diaphragm pump 12 via the second heater 10 .

[0056] In the embodiment of the present application, the nitrogen input unit 5 is configured to input nitrogen into the nitrogen purification unit 6. The nitrogen purification unit 6 is configured to purify the nitrogen and input the purified nitrogen into the heat exchanger 7. The heat exchanger 7 is configured to exchange heat between the received steam condensate and the purified nitrogen to obtain the heat-exchanged nitrogen. The heater 8 is configured to heat the heat-exchanged nitrogen according to the heating conditions to obtain the driving nitrogen, and input the driving nitrogen into the pneumatic diaphragm pump 12 to drive the pneumatic diaphragm pump 12 to work.

[0057] In the embodiment of the present application, the electronic-grade polysilicon delivery system further includes: a condensate pipe 11, a coil 18, and a drying chamber 19. The condensate pipe 11 has an input pipe opening and an output pipe opening. The input pipe opening of the condensate pipe 11 is configured to input steam condensate to the heat exchanger 7, and the output pipe opening of the condensate pipe 11 is configured to be coupled with the coil 18, and the coil 18 is spirally arranged on the drying chamber 19.

[0058] The drying chamber 19 includes a drying inlet configured to receive the nitrogen tail gas outputted by the second outlet unit 14 of the pneumatic diaphragm pump 12. Industrial silicon powder is arranged in the drying chamber 19, and the drying chamber 19 is configured to heat and dry the industrial silicon powder with the nitrogen tail gas.

[0059] Furthermore, the electronic-grade polysilicon delivery system also includes a steam condensation unit 20 , which is used to receive nitrogen in the industrial silicon powder brought out by the driven nitrogen in the coil 18 .

[0060] In the embodiment of the present application, the heating condition includes: when the temperature of the nitrogen after heat exchange is greater than or equal to 5°, stopping heating the nitrogen after heat exchange.

[0061] When the heater 8 provided in the electronic-grade polysilicon delivery system provided in the present application heats the heat-exchanged nitrogen, it is necessary to meet the requirement that when the temperature of the heat-exchanged nitrogen input into the heater 8 is less than 5°C, the heater 8 starts to heat the received heat-exchanged nitrogen until the temperature of the heat-exchanged nitrogen is greater than or equal to 5°C, and then stops heating the heat-exchanged nitrogen. The heated nitrogen is input from the heating outlet of the heater to the inlet unit of the pneumatic diaphragm pump 12, providing a power source for the pneumatic diaphragm pump 12.

[0062] This setting allows the electronic-grade polysilicon delivery system to operate normally when the temperature is below 4°C in winter, thereby avoiding the occurrence of diaphragm bursting in the diaphragm assembly of the pneumatic diaphragm pump in the electronic-grade polysilicon delivery system in a low-temperature environment, and further increasing the operating stability of the electronic-grade polysilicon delivery system.

[0063] In an embodiment of the present application, the material input unit 1 of the electronic-grade polysilicon conveying system is configured to input chlorosilane material into the system. After the chlorosilane material is processed by the heater 8 and the pneumatic diaphragm pump 12, the target material is output from the first outlet unit 13 of the pneumatic diaphragm pump 12, and the output target material includes chlorosilane.

[0064] like Figure 1 As shown, the output target material outputted from the first outlet unit 13 of the pneumatic diaphragm pump 12 is placed in the output material unit 15 .

[0065] In the embodiment of the present application, the electronic grade polysilicon delivery system further includes: a filter 16, and the filter 16 is disposed on the drying bin 19 and connected to the drying bin 19. The filter 16 is configured to filter the moisture in the industrial silicon powder in the drying bin 19.

[0066] Furthermore, in the embodiment of the present application, the electronic-grade polysilicon delivery system also includes an emptying unit 17, and the emptying unit 17 is connected to the filter 16 through a pipeline, and the emptying unit 17 is used to discharge the water filtered out of the filter 16 to the outside.

[0067] In the embodiment of the present application, the pneumatic diaphragm pump 12 also includes a cavity, and the diaphragm assembly is arranged in the cavity. The material of the cavity includes: PTFE. This arrangement can avoid corrosion and wear of the conveyed material, thereby extending the service life of the pneumatic diaphragm pump and reducing the generation of impurities.

[0068] Based on the above embodiments, the present application also provides a specific embodiment.

[0069] For example, in this specific embodiment, first, in the process of conveying chlorosilane material by the electronic-grade polysilicon conveying system, the diaphragm pump adopts an air-operated diaphragm pump 12, and the material of the diaphragm assembly of the air-operated diaphragm pump 12 is selected as PTFE, and the material of the cavity of the air-operated diaphragm pump 12 is also selected as PTFE.

[0070] The cavity is the part of the pneumatic diaphragm pump 12 that contains the material. By providing a diaphragm assembly of PTFE material inside the cavity, the cavity can be further protected from erosion by corrosive materials, while reducing direct contact between the material and the cavity, thereby reducing the risk of impurities being introduced.

[0071] Secondly, the driving nitrogen in the pneumatic diaphragm pump 12 is obtained by passing the nitrogen through the nitrogen purification unit, entering the heat exchanger 7, and exchanging heat with steam condensate to obtain heat-exchanged nitrogen. The heater 8 heats the heat-exchanged nitrogen according to the heating conditions to obtain the driving nitrogen, and inputs the driving nitrogen into the pneumatic diaphragm pump 12 to drive the pneumatic diaphragm pump to work. Among them, the heating conditions include: when the temperature of the heat-exchanged nitrogen is greater than or equal to 5°C, the electric heating stops heating the heat-exchanged nitrogen.

[0072] Next, the steam condensate after heat exchange with the nitrogen enters the coil 18 spirally arranged on the drying chamber 19 to be heated, so as to heat and dry the industrial silicon powder in the drying chamber 19.

[0073] Finally, the nitrogen tail gas discharged from the power source of the pneumatic diaphragm pump 12 is input from the drying inlet of the drying chamber 19 to heat and dry the industrial silicon powder, and then empty it after taking away the moisture. Compared with the existing system, the electronic grade polysilicon delivery system provided by the present application can not only realize the efficient delivery of chlorosilane produced by electronic grade polysilicon in a low temperature environment, but also has the advantages of simple structure, high efficiency, low cost, clean and energy-saving.

[0074] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0075] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An electronic grade polysilicon delivery system, characterized in that: include: Material input unit, air-operated diaphragm pump, and heater; The input port of the material input unit is connected to the heating inlet of the heater, and the heating outlet of the heater is connected to the inlet unit of the pneumatic diaphragm pump; the first outlet unit of the pneumatic diaphragm pump is configured to output the target material; Wherein, the material of the diaphragm assembly of the pneumatic diaphragm pump includes PTFE.

2. The system according to claim 1, characterized in that The material input unit includes a first material input unit, a second material input unit and a third material input unit; The first material input unit is configured to input chlorosilane material into the heater; The second material input unit comprises a nitrogen input unit, a nitrogen purification unit and a heat exchanger connected in sequence, and the second material input unit is configured to input the heat-exchanged nitrogen into the heater; The third material input unit is configured to input steam condensate into the heat exchanger.

3. The system according to claim 2, characterized in that The nitrogen input unit is configured to input nitrogen into the nitrogen purification unit; The nitrogen purification unit is configured to purify the nitrogen and input the purified nitrogen into the heat exchanger; The heat exchanger is configured to perform heat exchange between the received steam condensate and the purified nitrogen to obtain the heat-exchanged nitrogen; The heater is configured to heat the heat-exchanged nitrogen according to heating conditions to obtain driving nitrogen, and input the driving nitrogen into the pneumatic diaphragm pump to drive the pneumatic diaphragm pump to work.

4. The system according to claim 2, characterized in that Also includes: Condensate piping, coils, and drying chambers; The condensate pipe has an input pipe opening and an output pipe opening; The input pipe opening of the condensate pipe is configured to input steam condensate into the heat exchanger; the output pipe opening of the condensate pipe is configured to be coupled with the coil by pipe; The coil is spirally arranged on the drying bin; The drying chamber comprises a drying inlet, and the drying inlet is configured to receive the nitrogen tail gas output by the second output unit of the pneumatic diaphragm pump; Industrial silicon powder is arranged in the drying chamber, and the drying chamber is configured to utilize the nitrogen exhaust gas to heat and dry the industrial silicon powder.

5. The system according to claim 3, characterized in that The heating condition includes: when the temperature of the heat-exchanged nitrogen is greater than or equal to 5° C., stopping heating the heat-exchanged nitrogen.

6. The system according to claim 1, characterized in that The output target material includes chlorosilane.

7. The system according to claim 4, characterized in that Also includes: A filter, wherein the filter is disposed on the drying bin and connected to the drying bin; The filter is configured to filter the moisture in the industrial silicon powder in the drying bin.

8. The system according to claim 1, characterized in that The heater includes electric heat tracing.

9. The system according to claim 7, characterized in that Also includes: An emptying system, wherein the emptying system is connected to the filter through a pipeline; The emptying system is configured to receive the water filtered out by the filter and empty the water.

10. The system according to claim 1, characterized in that The pneumatic diaphragm pump further comprises: a cavity; The diaphragm assembly is arranged in the cavity, and the material of the cavity includes: PTFE.

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