Physical etching device for thick copper sandwich aluminum substrate

Abstract

The invention relates to the technical field of circuit printing devices, in particular to a thick copper sandwich aluminum substrate physical etching device which comprises a frame provided with a protective door and further comprises a high-energy particle generation mechanism, the high-energy particle generation mechanism comprises a microwave coupler installed in the frame, the output end of the microwave coupler is communicated with a processing pipe, and the output end of the processing pipe is communicated with a power source. An electromagnetic device is installed on the outer side of the treatment pipe, the microwave frequency and the magnetic field intensity meet the ECR condition, and the air inlet end of the treatment pipe communicates with an air inlet pipe. By arranging the vacuum etching mechanism and the arc-shaped shunting frame provided with the multidirectional uniform holes, high-energy ion beams are forcibly scattered and redistributed, it is ensured that the ion flux in the cross section of the vacuum tank is uniform, the problem of the edge effect of a large-area substrate is solved, the rotating disc drives the substrate to rotate through the driving motor, and by matching with static homogenization of the shunting frame, the efficiency is improved. The local etching difference is further eliminated, and dual uniformity guarantee of space uniform distribution and dynamic rotation compensation is realized.

Description

Technical Field

[0001] This invention relates to the field of circuit printing equipment technology, and in particular to a physical etching device for a thick copper sandwich aluminum substrate. Background Art

[0002] In printed circuit board (PCB) manufacturing, PCBs serve as the core connection carrier for electronic devices, and their manufacturing processes are constantly being upgraded to meet the miniaturization demands of electronic products. Current technologies often employ plasma etching for etching. Plasma etching generates plasma and utilizes the physical sputtering of high-energy ions and the chemical reaction of active free radicals to remove unwanted copper layers from the PCB surface. Volatile products are then extracted by a vacuum pump, achieving precise circuit pattern formation. In traditional etching, high-density plasma directly strikes the substrate, resulting in high single-point heat load. Due to the different thermal expansion coefficients of copper and aluminum, overheating can easily lead to copper-aluminum delamination and deformation.

[0003] In existing technologies, gas purifiers and quick-release vacuum systems are used to achieve gas purification, by-product collection, and rapid disassembly and assembly of pipelines. However, this method suffers from low plasma energy and poor uniformity of distribution, which cannot meet the high energy requirements and uniform etching of thick copper-core aluminum substrates, and is prone to copper-aluminum delamination. Microwave induction chambers, plasma chambers, and lifting door panels are used to achieve stable plasma generation and automatic opening and closing. However, this method lacks ion beam splitting design, has poor etching uniformity, does not solve the problem of charge accumulation in the etching of thick copper-core aluminum substrates, and lacks secondary plasma to assist in desorption of etching products. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies, such as low plasma energy, poor distribution uniformity, inability to meet the high energy requirements and uniform etching of thick copper sandwich aluminum substrates, and easy copper-aluminum delamination. Therefore, this invention proposes a physical etching device for thick copper sandwich aluminum substrates.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A physical etching apparatus for thick copper sandwich aluminum substrates includes a frame with a protective door mounted on the frame, and further includes: The high-energy particle generating mechanism includes a microwave coupler installed inside the frame, the output end of the microwave coupler is connected to a processing tube, an electromagnetic device is installed on the outside of the processing tube, wherein the microwave frequency and magnetic field strength satisfy the ECR condition, and the air inlet end of the processing tube is connected to an air inlet pipe. The three-grid clustering mechanism is installed inside the processing tube; The vacuum etching mechanism includes a vacuum tank mounted on a frame. The side of the vacuum tank is connected to the outlet end of the processing tube, and the bottom is connected to a vacuum device. The top of the vacuum tank is connected to a jet device, and the bottom of the inner tank is connected to a rotatable rotating disk. The outlet end of the jet device faces the rotating disk. A flow divider is fixedly connected inside the vacuum tank and is located on the outlet path of the processing tube.

[0006] Preferably, a placement assembly is connected inside the frame. The placement assembly includes a mounting plate fixedly connected inside the frame. Two roller plates are fixedly connected to the top of the mounting plate. The two roller plates are distributed in a figure-eight shape, and multiple rollers are rotatably connected to the top of each roller plate. The microwave coupler is placed between the tops of the two roller plates.

[0007] Preferably, a shielding cover is fixedly connected inside the frame, and multiple mounting rods are fixedly connected between the bottom of the shielding cover and the frame. The electromagnetic device and the processing tube are both located inside the shielding cover.

[0008] Preferably, the three-grid clustering mechanism includes a ground grid, an acceleration grid, and a deceleration grid installed sequentially inside the processing tube. The ground grid is close to the microwave coupler, the acceleration grid is connected to a high positive voltage, and the deceleration grid is connected to a negative voltage or a low positive voltage. The ground grid is close to the plasma source potential to stabilize the plasma boundary and sheath potential. The holes of the three grids are all aligned.

[0009] Preferably, a secondary coil is wound around the outer side of the end of the processing tube near the vacuum tank, and the secondary coil is located inside the shield.

[0010] Preferably, the end of the processing tube near the vacuum tank is connected to a sealing plug, and the side of the vacuum tank is connected to a sealing interface, with the sealing plug and the sealing interface sealingly connected and engaged.

[0011] Preferably, the vacuum equipment includes a vacuum device and a venting device installed inside the frame. The vacuum device has a suction pipe connected to its suction end. The suction pipe is sealed at the end away from the vacuum device and extends into the interior of the vacuum tank. The suction pipe has multiple suction holes on its side that communicate with the interior of the vacuum tank. The venting device has a pressure relief end connected to the vacuum tank.

[0012] Preferably, the air inlet end of the jet device and the end of the air inlet pipe away from the processing pipe are both connected to an external argon gas source, and a small radio frequency electrode is installed inside the jet device.

[0013] Preferably, a fixed frame is installed inside the frame, a drive motor is installed on the fixed frame, and a sealed coupling penetrating the bottom of the vacuum tank is installed between the output end of the drive motor and the rotating disk.

[0014] Preferably, the diverter frame is arc-shaped and has multiple uniform holes through it. The inlet ends of the multiple uniform holes all face the processing pipe, and the outlet ends are partially facing the center of the vacuum tank and partially facing the two sides of the vacuum tank.

[0015] Compared with the prior art, the advantages of the present invention are: 1. This invention, by setting up a vacuum etching mechanism with an arc-shaped shunt frame having multi-directional uniform holes, forcibly disperses and redistributes the high-energy ion beam, ensuring uniform ion flux within the cross-section of the vacuum tank, and solving the edge effect problem of large-area substrates. The rotating disk drives the substrate to rotate through a drive motor, which, together with the static homogenization of the shunt frame, further eliminates local etching differences, achieving dual uniformity assurance of spatial uniform distribution and dynamic rotation compensation. It is suitable for etching copper-aluminum composite substrates, reducing copper-aluminum delamination and warping caused by local overheating.

[0016] 2. This invention, by setting up a high-energy particle generation mechanism, precisely matches the microwave frequency with the magnetic field strength generated by the electromagnetic device, and utilizes the resonance effect to efficiently generate high-density, high-energy plasma, solving the problem of low ion density and insufficient energy in traditional plasma sources that lead to slow etching rates for thick copper. By setting up a three-grid beam-gathering mechanism, using a three-grid structure of grounding grid, accelerating grid, and decelerating grid, and in conjunction with the secondary coil at the processing tube outlet, a dual control of electrostatic lens and magnetic field focusing is formed, effectively gathering the ion beam and reducing the loss of the ion beam when passing through the processing tube. Combined with the vacuum etching mechanism, this invention specifically solves the problems of low efficiency, poor uniformity, and easy overheating damage in the etching of thick copper sandwich aluminum substrates.

[0017] 3. This invention incorporates a jetting device that continuously injects argon gas. This device guides the plasma to the substrate surface to enhance etching efficiency and removes the heat generated by ion bombardment of the substrate through airflow, thus solving the problem of substrate overheating caused by high energy input in thick copper etching and balancing the thermal stress difference between copper and aluminum. The small radio frequency electrode built into the jetting device locally excites the ejected argon gas to generate low-density secondary plasma. This plasma provides electrons to neutralize the positive charge accumulated on the substrate surface and forms a conductive channel to assist in the desorption of etching products. This solves the problems of charge accumulation damaging devices and product residue affecting accuracy in traditional etching. Attached Figure Description

[0018] Figure 1 This is an isometric view of the overall physical etching device for a thick copper sandwich aluminum substrate proposed in this invention.

[0019] Figure 2 This is a schematic diagram of the internal structure of a physical etching device for a thick copper sandwich aluminum substrate proposed in this invention.

[0020] Figure 3 This is a schematic diagram of the roller plate and mounting plate structure of a physical etching device for a thick copper sandwich aluminum substrate proposed in this invention.

[0021] Figure 4This is a schematic diagram of the electromagnetic device and secondary coil structure of a physical etching apparatus for a thick copper sandwich aluminum substrate proposed in this invention.

[0022] Figure 5 This is a schematic diagram of the jetting device, vacuum tank, and vacuum equipment of a physical etching apparatus for a thick copper sandwich aluminum substrate proposed in this invention.

[0023] Figure 6 This is a schematic diagram of the flow divider frame and uniform hole structure of a physical etching device for a thick copper sandwich aluminum substrate proposed in this invention.

[0024] Figure 7 This is a schematic diagram of the half-section structure of the processing tube of the physical etching device for a thick copper sandwich aluminum substrate proposed in this invention.

[0025] In the diagram: 1. Frame; 2. Protective door; 3. Grounding grid; 4. Acceleration grid; 5. Jet device; 6. Vacuum tank; 7. Diverter frame; 8. Uniform orifice; 9. Evacuation pipe; 10. Fixing frame; 11. Rotating disk; 12. Coupling; 13. Drive motor; 14. Vacuum device; 15. Venting device; 16. Sealing interface; 17. Shielding cover; 18. Mounting rod; 19. Mounting plate; 20. Microwave coupler; 21. Roller plate; 22. Electromagnetic device; 23. Inlet pipe; 24. Sealing plug; 25. Secondary coil; 26. Processing pipe; 27. Deceleration grid. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Reference Figures 1-4 and Figure 7 A physical etching apparatus for thick copper sandwich aluminum substrates includes a frame 1, a protective door 2 mounted on the frame 1, and further includes: The high-energy particle generating mechanism includes a microwave coupler 20 installed inside the frame 1. The output end of the microwave coupler 20 is connected to a processing tube 26. An electromagnetic device 22 is installed on the outside of the processing tube 26. The microwave frequency and magnetic field strength satisfy the ECR condition. The air inlet end of the processing tube 26 is connected to an air inlet pipe 23.

[0028] The ECR condition, or electron cyclotron resonance condition, is achieved by using the resonance effect of microwaves and magnetic fields to obtain a high density of high-energy electrons and ions.

[0029] The frame 1 is connected to a placement component, which includes a mounting plate 19 fixedly connected inside the frame 1. Two roller plates 21 are fixedly connected to the top of the mounting plate 19. The two roller plates 21 are distributed in a figure-eight shape, and multiple rollers are rotatably connected to the top of each roller plate 21. The microwave coupler 20 is placed between the tops of the two roller plates 21.

[0030] When the microwave coupler 20 is not in use, it can be directly removed from the two roller plates 21 for easy maintenance.

[0031] The microwave coupler 20 uses existing technology and is an energy coupling device that efficiently transmits external microwave energy to the cavity to excite gas and generate plasma.

[0032] A shielding cover 17 is fixedly connected inside the frame 1. Multiple mounting rods 18 are fixedly connected between the bottom of the shielding cover 17 and the frame 1. The electromagnetic device 22 and the processing tube 26 are both located inside the shielding cover 17.

[0033] The shielding cover 17 can reduce interference from the external environment and also prevent strong electromagnetic fields from affecting other external equipment.

[0034] The three-grid clustering mechanism is installed inside the processing tube 26.

[0035] The three-grid clustering mechanism includes a ground grid 3, an acceleration grid 4, and a deceleration grid 27, which are installed sequentially inside the processing tube 26. The ground grid 3 is close to the microwave coupler 20, the acceleration grid 4 is connected to a high positive voltage, and the deceleration grid 27 is connected to a negative voltage or a low positive voltage. The ground grid 3 is close to the plasma source potential and is used to stabilize the plasma boundary and sheath potential. The holes of the three grids are all aligned.

[0036] A secondary coil 25 is wound around the outer side of the processing tube 26 near the vacuum tank 6, and the secondary coil 25 is located inside the shield 17.

[0037] Reference Figure 5 and Figure 6 The vacuum etching mechanism includes a vacuum tank 6 mounted on a frame 1. The side of the vacuum tank 6 is connected to the outlet end of the processing tube 26, and the bottom is connected to a vacuum device. The top of the vacuum tank 6 is connected to a jet device 5, and the inner bottom is connected to a rotatable rotating disk 11. The outlet end of the jet device 5 faces the rotating disk 11. A flow divider 7 is fixedly connected inside the vacuum tank 6 and is located on the outlet path of the processing tube 26.

[0038] The processing tube 26 is connected to a sealing plug 24 at one end near the vacuum tank 6, and a sealing interface 16 is connected to the side of the vacuum tank 6. The sealing plug 24 and the sealing interface 16 are sealed and connected.

[0039] The vacuum equipment includes a vacuum device 14 and a venting device 15 installed inside the frame 1. The vacuum device 14 has a vacuum pipe 9 connected to its suction end. The end of the vacuum pipe 9 away from the vacuum device 14 is sealed and extends into the interior of the vacuum tank 6. The side of the vacuum pipe 9 has multiple suction holes that communicate with the interior of the vacuum tank 6. The venting device 15 has a pressure relief end connected to the vacuum tank 6.

[0040] Both the vacuum device 14 and the venting device 15 adopt existing technologies. The vacuum device 14 evacuates the inside of the vacuum tank 6 through the evacuation pipe 9, so that the inside of the vacuum tank 6 is kept in a near-vacuum state, providing a stable working environment for etching. When the venting device 15 is working, it safely restores the air pressure inside the vacuum tank 6 to normal.

[0041] The air inlet of the jet device 5 and the end of the air inlet pipe 23 away from the processing pipe 26 are both connected to an external argon gas source. A small radio frequency electrode is installed inside the jet device 5.

[0042] The miniature radio frequency electrode uses existing technology and is a micro-electrode component that generates secondary plasma by applying radio frequency energy to locally excite the ejected gas.

[0043] A fixed frame 10 is installed inside the frame 1. A drive motor 13 is installed on the fixed frame 10. A coupling 12 that seals and penetrates the bottom of the vacuum tank 6 is installed between the output end of the drive motor 13 and the rotating disk 11.

[0044] The diversion frame 7 is arc-shaped and has multiple uniform holes 8 through it. The air inlet ends of the multiple uniform holes 8 are all facing the processing pipe 26, and the air outlet ends are partly facing the center of the vacuum tank 6 and partly facing the two sides of the vacuum tank 6.

[0045] When the plasma inside the processing tube 26 flows to the splitter frame 7, it is evenly dispersed into the interior of the vacuum tank 6 along the arc-shaped surface of the splitter frame 7 and multiple uniform holes 8, forming a stable and uniform plasma distribution inside the vacuum tank 6, thereby improving the uniformity of etching.

[0046] In use, 2.45 GHz microwaves are injected into the microwave coupler 20, while the electromagnetic device 22 is activated. Argon gas required for etching is injected into the processing tube 26 through the air inlet pipe 23. The magnetic field strength and microwave frequency are matched and designed to generate electron cyclotron resonance inside the processing tube 26. Through the resonance effect of microwave and magnetic field, high-density high-energy electrons and ions are generated efficiently. The high-energy electrons collide with argon gas molecules in the cavity, exciting the gas molecules to generate plasma, thus obtaining plasma containing high-energy electrons, ions and free radical active substances.

[0047] The generated plasma passes through the grounding grid 3, acceleration grid 4 and deceleration grid 27 arranged in sequence in the processing tube 26. A secondary coil 25 is also provided at the outlet of the processing tube 26.

[0048] The holes in the three-layer grid are strictly aligned to form an electrostatic lens. The accelerating grid 4 is connected to a high positive voltage, such as hundreds to thousands of volts, to create a strong electric field between the grounding grid 3 and the accelerating grid 4. This pulls positively charged argon ions out of the plasma and accelerates them to form a directional high-energy ion beam.

[0049] The deceleration grid 27 is connected to a negative voltage or a low positive voltage, which can suppress electron backflow and prevent electrons escaping from the downstream from being attracted back to the acceleration grid 4 and impacting the acceleration grid 4, thus protecting the acceleration grid 4; at the same time, it optimizes ion beam focusing. Adjusting the voltage of the deceleration grid 27 can affect the divergence angle of the ion beam, making the ion beam more collimated.

[0050] The grounding grid 3, which is usually close to or the same as the plasma source potential, is used to define the plasma boundary potential and stabilize the plasma sheath. The plasma source is integrated at the front end of the processing tube 26 and provides a positive potential reference through the grounding grid 3.

[0051] The ion beam is accelerated and concentrated by a three-grid beam-gathering mechanism, which reduces the loss of the ion beam as it passes through the processing tube 26.

[0052] A secondary coil 25 is provided at the outlet end of the processing tube 26. When the secondary coil 25 is energized, it applies a magnetic field at the ion beam outlet, generating a Lorentz force on the positively charged ion beam. This force is used to further focus, collimate, or deflect the ion beam, reduce ion beam divergence, and improve ion flux density and uniformity.

[0053] The sealing plug 24 and the sealing interface 16 are sealed together. The ion beam generated inside the processing tube 26 enters the interior of the vacuum tank 6 through the sealing plug 24 and the sealing interface 16. The vacuum device 14 is started in advance, and the interior of the vacuum tank 6 is evacuated through the suction pipe 9 in the middle of the vacuum tank 6.

[0054] The ion beam entering the vacuum chamber 6 first contacts the splitter frame 7. The ion beam is split through the splitter frame 7 and evenly dispersed into the interior of the vacuum chamber 6 through multiple uniform holes 8. This forces the ion beam, which may have a high density at the center, to be dispersed and redistributed, so that it evenly fills the entire cross-section of the vacuum chamber 6. This ensures that the ion flux received at any position on the substrate surface is highly uniform. Thus, when etching a large area of ​​thick copper layer, it ensures that the etching depth of the whole board is consistent and the line width is uniform, avoiding the problem of too fast etching at the center or insufficient etching at the edges.

[0055] Meanwhile, the uniform ion beam through the shunt frame 7 effectively avoids the problem of copper and aluminum overheating, delamination, and deformation caused by high single-point heat load.

[0056] When the jet device 5 is in operation, its outlet jets argon gas toward the substrate on the rotating disk 11. The parts of the substrate that do not need to be etched are covered with shielding material. The argon gas flow guides the plasma inside the vacuum tank 6 to the surface of the substrate for etching and also has a cooling effect. The continuously injected argon gas flow over the surface of the substrate can effectively remove some of the heat generated by ion bombardment, significantly reducing the overall temperature and thermal gradient of the substrate. This reduces the risk of cracking of thick copper layers, delamination of copper-aluminum interlayer interfaces, and warping of aluminum substrates caused by thermal stress. It is suitable for heat-sensitive substrates and high-power, long-term etching.

[0057] A small radio frequency electrode is integrated inside the jet device 5. The ejected gas is locally excited to generate a low-density, low-temperature secondary plasma. The secondary plasma provides electrons to neutralize the positive charge accumulated on the substrate surface due to high-energy ion bombardment, thus preventing arc discharge damage to the device due to charge accumulation. At the same time, the secondary plasma forms a conductive channel, increasing the low-energy ion density near the substrate and assisting in the desorption of etching products.

[0058] The drive motor 13 at the bottom of the fixed frame 10 works, and its output end drives the rotating disk 11 to rotate through the coupling 12, thereby driving the substrate to rotate and making the substrate more uniformly etched.

[0059] After the substrate etching process is completed, the vacuum tank 6 is safely depressurized through the venting device 15, and finally the etched substrate is taken out.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A physical etching apparatus for a thick copper sandwich aluminum substrate, comprising a frame (1) and a protective door (2) mounted on the frame (1), characterized in that, Also includes: The high-energy particle generating mechanism includes a microwave coupler (20) installed inside the frame (1). The output end of the microwave coupler (20) is connected to a processing tube (26). An electromagnetic device (22) is installed on the outside of the processing tube (26). The microwave frequency and magnetic field strength satisfy the ECR condition. The air inlet end of the processing tube (26) is connected to an air inlet pipe (23). The three-grid clustering mechanism is installed inside the processing tube (26); The vacuum etching mechanism includes a vacuum tank (6) mounted on a frame (1). The side of the vacuum tank (6) is connected to the outlet end of the processing tube (26), and the bottom is connected to a vacuum device. The top of the vacuum tank (6) is connected to a jet device (5), and the bottom of the inner part is connected to a rotatable rotating disk (11). The outlet end of the jet device (5) faces the rotating disk (11). A flow divider (7) is fixedly connected inside the vacuum tank (6). The flow divider (7) is located on the outlet path of the processing tube (26).

2. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, The frame (1) is connected to a placement component, which includes a mounting plate (19) fixedly connected inside the frame (1). Two roller plates (21) are fixedly connected to the top of the mounting plate (19). The two roller plates (21) are distributed in a figure-eight shape, and multiple rollers are rotatably connected to the top of each. The microwave coupler (20) is placed between the tops of the two roller plates (21).

3. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, A shield (17) is fixedly connected inside the frame (1). Multiple mounting rods (18) are fixedly connected between the bottom of the shield (17) and the frame (1). The electromagnetic device (22) and the processing tube (26) are both located inside the shield (17).

4. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 3, characterized in that, The three-grid clustering mechanism includes a ground grid (3), an acceleration grid (4), and a deceleration grid (27) installed sequentially inside the processing tube (26). The ground grid (3) is close to the microwave coupler (20), the acceleration grid (4) is connected to a high positive voltage, and the deceleration grid (27) is connected to a negative voltage or a low positive voltage. The ground grid (3) is close to the plasma source potential and is used to stabilize the plasma boundary and sheath potential. The holes of the three grids are all aligned.

5. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 4, characterized in that, A secondary coil (25) is wound around the outer side of the processing tube (26) near the vacuum tank (6), and the secondary coil (25) is located inside the shield (17).

6. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, The processing tube (26) is connected to a sealing plug (24) at one end near the vacuum tank (6), and a sealing interface (16) is connected to the side of the vacuum tank (6). The sealing plug (24) and the sealing interface (16) are sealed and connected.

7. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, The vacuum equipment includes a vacuum device (14) and a venting device (15) installed inside the frame (1). The vacuum device (14) has a suction pipe (9) connected to its suction end. The suction pipe (9) is sealed at one end away from the vacuum device (14) and extends into the interior of the vacuum tank (6). The suction pipe (9) has multiple suction holes on its side that communicate with the interior of the vacuum tank (6). The venting device (15) has a pressure relief end connected to the vacuum tank (6).

8. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, The air inlet of the jet device (5) and the end of the air inlet pipe (23) away from the processing pipe (26) are connected to an external argon gas source. A small radio frequency electrode is installed inside the jet device (5).

9. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, A fixed frame (10) is installed inside the frame (1), and a drive motor (13) is installed on the fixed frame (10). A coupling (12) that seals and penetrates the bottom of the vacuum tank (6) is installed between the output end of the drive motor (13) and the rotating disk (11).

10. The physical etching apparatus for thick copper sandwich aluminum substrates according to claim 1, characterized in that, The diversion frame (7) is arc-shaped and has multiple uniform holes (8) through it. The air inlet of the multiple uniform holes (8) is facing the processing pipe (26), and the air outlet is partly facing the center of the vacuum tank (6) and partly facing the two sides of the vacuum tank (6).

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