Tin alloy target material pouring method and equipment for inhibiting shrinkage cavity and composition segregation

Abstract

The invention belongs to the technical field of tin alloy target material pouring, particularly relates to a tin alloy target material pouring method and equipment for inhibiting shrinkage cavity and composition segregation, and provides the following scheme aiming at the core problems of volume shrinkage and composition segregation during solidification, easy target material shrinkage cavity, shrinkage porosity and nonuniform composition in tin alloy pouring: a vacuum induction melting furnace is adopted; a feeding box is arranged at the top end of the vacuum induction melting furnace, an out-furnace pipeline is fixedly connected to the outer side of the vacuum induction melting furnace, and an external furnace is arranged at the bottom end of the out-furnace pipeline. The tin alloy target material pouring method and equipment for inhibiting shrinkage cavities and composition segregation have the advantages that the pressure sealing cake applies constant low-pressure mechanical pressure to melt in the mold, the melt is forced to continuously shrink and feed in the solidification process, gaps formed by volume shrinkage are directly filled, shrinkage cavities and shrinkage porosity are reduced to the maximum extent, and the casting quality of the tin alloy target material is improved. And the use effect of the internal density of the target is improved.

Description

Technical Field

[0001] This invention relates to the field of tin alloy target casting technology, and in particular to a method and equipment for casting tin alloy targets to suppress shrinkage cavities and component segregation. Background Technology

[0002] Tin alloy target casting equipment is mainly used in fields such as electronic packaging and semiconductor manufacturing, especially as a target material in sputtering coating processes. Its preparation involves high-precision melting and forming processes, which must meet the strict requirements of electronic materials for compositional uniformity and density.

[0003] The biggest challenge in the casting process is the volume shrinkage and compositional segregation during the solidification of tin alloys. This can lead to shrinkage cavities, porosity, and uneven composition inside the target material, thus affecting the stability of sputtering and the uniformity of the film. Summary of the Invention

[0004] This invention discloses a method and equipment for casting tin alloy targets to suppress shrinkage cavities and component segregation. The aim is to solve the core problem in tin alloy casting: volume shrinkage and component segregation during solidification, which easily lead to shrinkage cavities, porosity, and uneven composition in the target material, thus affecting sputtering stability and film uniformity.

[0005] The present invention proposes a method for casting tin alloy targets to suppress shrinkage cavities and compositional segregation, comprising the following steps: S1. Based on the performance requirements of the target material, such as purity, electrical properties, and bonding strength with the backing plate, accurately calculate the ratio of tin to other alloying elements such as indium, silver, and antimony, or oxygen-free copper / aluminum backing plate. Remove oxides, oil, and other impurities from the surface of the raw material. Common methods include mechanical grinding, pickling, and ultrasonic cleaning. Thoroughly dry the cleaned raw material to prevent moisture from being carried into the melt. Pickling involves immersing in a 5%-10% hydrochloric acid solution at room temperature for 15-20 minutes. Ultrasonic cleaning parameters are 300W power, 40kHz frequency, and 20 minutes. Drying is performed using 100℃ hot air circulation for 2 hours to ensure that the moisture content of the raw material is ≤0.05%. S2. Mold Preparation: If casting into an independent target material, a graphite mold or metal mold is required. The mold must be pre-coated with a refractory coating, such as yttrium oxide or boron nitride, to prevent sticking and facilitate demolding. More commonly, a tin alloy is directly cast onto a backing plate, such as oxygen-free copper or aluminum, to form a composite target material. The backing plate needs to undergo strict pretreatment, including: ① mechanical polishing to a surface roughness Ra≤0.8μm; ② passivation with 5% nitric acid solution for 10min; ③ ultrasonic cleaning, with the same parameters as the raw material cleaning; ④ preheating and drying at 200℃. The acceptance standard is that there are no oxide spots on the backing plate surface and oil residue ≤5mg / m². S3. Preheating: Before casting, preheat the back plate to a certain temperature, such as 200-300°C, to remove adsorbed gases on the surface and reduce the temperature difference with the molten alloy, preventing poor bonding and rapid cooling. Load the pretreated raw material into a vacuum induction melting furnace, usually made of graphite or ceramic. Close the furnace door and evacuate the furnace chamber to a high vacuum, such as 10°C. -2 Pa~10 -3 Pa, to remove oxygen, nitrogen and water vapor adsorbed in the furnace and raw materials to the maximum extent; S4. Melting and Refining: Under vacuum or with the protection of an inert gas such as argon, the raw materials are heated and melted at a rate of 5-10℃ / min. After melting, the material is held at this temperature for 30-60 minutes. The argon flow rate is 0.5-1L / min. The impurity control index is lead ≤0.001% and bismuth ≤0.0005%, verified by ICP-MS. In an induction furnace, the alloy composition is homogenized by electromagnetic induction. The material is held in a molten state for a period of time to allow low-melting-point impurities to volatilize and to promote the floating of gases and inclusions. S5. Casting: When the melt reaches a preset, precisely controlled superheat that is a certain temperature above the liquidus, the molten alloy liquid is poured smoothly and continuously into a crystallizer or mold with a pre-set back plate or mold using a casting device. In order to obtain a dense and uniform microstructure, the ingot after casting needs to be cooled under controlled conditions. The cooling rate is adjusted according to the thickness of the target material: when the thickness is 5-10 mm, the cooling rate is 2-5℃ / min; when the thickness is 10-20 mm, the cooling rate is 1-2℃ / min. Gradient cooling is achieved through a directional thermal field control component to obtain fine grains. S6. Demolding: After the ingot has completely solidified and cooled to room temperature, the vacuum is broken, the ingot is removed from the furnace, and the tin alloy target is removed from the mold, or at this time the metallurgical bonding with the back plate has been completed.

[0006] A tin alloy target casting device, applied to a tin alloy target casting method for suppressing shrinkage cavities and component segregation as described above, includes a vacuum induction melting furnace. A feed box is located at the top of the vacuum induction melting furnace. An external pipeline is fixedly connected to the outside of the vacuum induction melting furnace. An external furnace is located at the bottom end of the external pipeline. A melting furnace is located inside the vacuum induction melting furnace. A mold is located inside the external furnace. A pressure-assisted solidification assembly is located at the top of the mold. The pressure-assisted solidification assembly includes two symmetrical frames. A connecting frame is fixedly connected to one opposite side of each symmetrical frame. A sealing frame is fixedly connected to one side of one of the connecting frames. A drive motor is located inside the sealing frame. The power output shaft of the drive motor is connected to a threaded rod via a coupling. The end of the threaded rod away from the drive motor is movably connected to the inside of the connecting frame. Guide rods are fixedly connected to both sides inside the other connecting frame.

[0007] In a preferred embodiment, both the threaded rod and the guide rod are provided with movable seats on their outer sides. Each of the two connecting frames has a sliding groove hole on its opposite side. The movable seats are movably connected to the inside of the sliding groove hole. An internal frame is fixedly connected to the opposite side of the movable seats. A servo motor is provided on the side of the internal frame near the sealing frame. The power output shaft of the servo motor is connected to a rotating shaft through a coupling. The side of the rotating shaft away from the servo motor is movably connected to the inside of the internal frame. A pulling rope is wound around the outside of the rotating shaft.

[0008] In a preferred embodiment, two spring rods are fixedly connected to the bottom end of the built-in frame, and pressure sealing discs are fixedly connected to the bottom ends of both the spring rods and the pulling rope, with the pressure sealing discs located directly above the mold.

[0009] In a preferred embodiment, a directional thermal field control component is provided on the outer side of the mold. The directional thermal field control component includes a stand, a vacuum motor is provided at the top of the stand, the power output shaft of the vacuum motor is connected to a rotating rod through a coupling, and both ends of the rotating rod are movably connected to the inner side of the stand. A guide thread is fixedly connected to the outer side of the rotating rod.

[0010] In a preferred embodiment, a movable member is provided on the outer side of the guide threaded member, a connecting member is fixedly connected to one side of the movable member, and two straight rods are fixedly connected to the inner side of the upright. The connecting member is movably connected to the outer side of the straight rods, and an annular frame is fixedly connected to the side of the connecting member away from the guide threaded member.

[0011] In a preferred embodiment, a temperature control ring is provided on the inner side of the ring frame, an extension frame is fixedly connected to one side of the connector, a temperature sensor is fixedly connected to the side of the extension frame near the temperature control ring, and the temperature control ring is in contact with the outer side of the mold.

[0012] In a preferred embodiment, a fence is provided on the outside of the feed box, and the fence is fixedly connected to the top of the vacuum induction melting furnace by bolts. The gap between the fence and the feed box is ≤5mm, and the top of the feed box is provided with a feed inlet. An external pipeline is fixedly connected to the outside of the vacuum induction melting furnace.

[0013] In a preferred embodiment, a placement frame is fixedly connected to the bottom inner side of the vacuum induction melting furnace. Two movable frames are provided at the top of the placement frame. The movable frames slide with the guide rail of the placement frame via a slider, with a sliding accuracy of ≤0.05mm. The top of the movable frames is fixedly connected to the top of the melting furnace, and the melting furnace is movably connected to the inner side of the placement frame. A pouring port is provided at the top of the melting furnace.

[0014] In a preferred embodiment, a linear guide rail is fixedly connected to the inner side of the conveying shell, a casting groove is provided at the top of the linear guide rail, a vacuum pipe is fixedly connected to the top of the conveying shell, an electromagnetic stirrer is fixedly connected to the inner side of the external furnace, and a mold is provided at the top of the electromagnetic stirrer. A suction pipe is fixedly connected to the outer side of the external furnace, and a vacuum device is fixedly connected to one end of both the vacuum pipe and the external furnace pipe.

[0015] As can be seen from the above, the tin alloy target casting method and equipment for suppressing shrinkage cavities and component segregation provided by the present invention has the effect of applying constant low-pressure mechanical pressure to the melt in the mold by the pressure sealing cake, forcing the melt to continuously shrink and compensate during the solidification process, directly filling the gaps formed by volume shrinkage, minimizing the generation of shrinkage cavities and porosity, and improving the internal density of the target material. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a tin alloy target casting method for suppressing shrinkage cavities and component segregation proposed in this invention. Figure 2 This is a schematic diagram of the overall structure of a tin alloy target casting device proposed in this invention; Figure 3 This is a schematic diagram of the vacuum induction melting furnace part of a tin alloy target casting equipment proposed in this invention; Figure 4 This is a schematic diagram of the internal structure of a vacuum induction melting furnace for a tin alloy target casting device proposed in this invention; Figure 5 This is a schematic diagram of the external furnace section of a tin alloy target casting device proposed in this invention; Figure 6 This is a schematic diagram of the pressure-assisted solidification component structure of a tin alloy target casting equipment proposed in this invention; Figure 7 This is a schematic diagram of a pressure-assisted solidification component of a tin alloy target casting device proposed in this invention. Figure 8 This is a schematic diagram of the directional thermal field control component of a tin alloy target casting equipment proposed in this invention.

[0017] In the diagram: 1. Vacuum induction melting furnace; 2. Enclosure; 3. Feed box; 4. Feed inlet; 5. External furnace pipe; 6. Vacuum pipe; 7. Vacuum device; 8. Conveying shell; 9. Suction pipe; 10. External furnace; 11. Pressure-assisted solidification assembly; 1101. Symmetrical frame; 1102. Connecting frame; 1103. Sealing frame; 1104. Drive motor; 1105. Threaded rod; 1106. Guide rod; 1107. Movable seat; 1108. Internal frame; 1109. Servo motor; 1110. Rotating shaft; 1111. Pulling rope; 1112. 11. Spring rod; 12. Pressure sealing disc; 13. Linear guide rail; 14. Casting trough; 15. Melting furnace; 16. Directional thermal field control assembly; 17. Stand; 18. Vacuum motor; 19. Rotating rod; 10. Linear rod; 10. Moving part; 11. Connecting part; 12. Ring frame; 13. Temperature control ring; 14. Guide threaded part; 15. Extension frame; 16. Temperature sensor; 17. Placement rack; 18. Movable rack; 19. Electromagnetic stirrer; 20. Mold; 11. Sprue. Detailed Implementation

[0018] 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.

[0019] The present invention discloses a method and equipment for casting tin alloy targets to suppress shrinkage cavities and component segregation. It is mainly applied to scenarios where the core problem of tin alloy casting is the volume shrinkage and component segregation during solidification, which easily leads to shrinkage cavities, porosity, and uneven composition of the target material, thereby affecting sputtering stability and film uniformity.

[0020] Reference Figure 1 A method for casting tin alloy targets to suppress shrinkage cavities and compositional segregation includes the following steps: S1. Based on the performance requirements of the target material, such as purity, electrical properties, and bonding strength with the backing plate, accurately calculate the ratio of tin to other alloying elements such as indium, silver, and antimony, or oxygen-free copper / aluminum backing plate. Remove oxides, oil, and other impurities from the surface of the raw material. Common methods include mechanical grinding, pickling, and ultrasonic cleaning. Thoroughly dry the cleaned raw material to prevent moisture from being carried into the melt. Pickling involves immersing in a 5%-10% hydrochloric acid solution at room temperature for 15-20 minutes. Ultrasonic cleaning parameters are 300W power, 40kHz frequency, and 20 minutes. Drying is performed using 100℃ hot air circulation for 2 hours to ensure that the moisture content of the raw material is ≤0.05%. S2. Mold 19 Preparation: If casting into an independent target material, a graphite mold 19 or a metal mold 19 is required. The mold 19 needs to be pre-coated with a refractory coating, such as yttrium oxide or boron nitride, to prevent sticking and facilitate demolding. More commonly, a tin alloy is directly cast onto a backing plate, such as oxygen-free copper or aluminum, to form a composite target material. The backing plate needs to undergo strict pretreatment, including: ① mechanical polishing to a surface roughness Ra≤0.8μm; ② passivation with 5% nitric acid solution for 10min; ③ ultrasonic cleaning, with the same parameters as the raw material cleaning; ④ preheating and drying at 200℃. The acceptance standard is that there are no oxide spots on the backing plate surface and oil residue ≤5mg / m³. S3. Preheating: Before casting, preheat the back plate to a certain temperature, such as 200-300°C, to remove adsorbed gases on the surface and reduce the temperature difference with the molten alloy, preventing poor bonding and rapid cooling. Load the pretreated raw material into a vacuum induction melting furnace 1, usually made of graphite or ceramic. Close the furnace door and evacuate the furnace chamber to a high vacuum, such as 10°C. -2 Pa~10 -3 Pa, to remove oxygen, nitrogen and water vapor adsorbed in the furnace and raw materials to the maximum extent; S4. Melting and Refining: Under vacuum or with the protection of an inert gas such as argon, the raw materials are heated and melted at a rate of 5-10℃ / min. After melting, the material is held at this temperature for 30-60 minutes. The argon flow rate is 0.5-1L / min. The impurity control index is lead ≤0.001% and bismuth ≤0.0005%, verified by ICP-MS. In an induction furnace, the alloy composition is homogenized by electromagnetic induction. The material is held in a molten state for a period of time to allow low-melting-point impurities to volatilize and to promote the floating of gases and inclusions. S5. Casting: When the melt reaches the preset, precisely controlled superheat temperature above the liquidus, the molten alloy liquid is smoothly and continuously poured into the crystallizer or mold with a pre-set back plate or mold 19 using a casting device. In order to obtain a dense and uniform microstructure, the ingot after casting needs to be cooled under controlled conditions. The cooling rate is adjusted according to the thickness of the target material: when the thickness is 5-10 mm, the cooling rate is 2-5℃ / min; when the thickness is 10-20 mm, the cooling rate is 1-2℃ / min. Gradient cooling is achieved through the directional thermal field control component to obtain fine grains. S6. Demolding: After the ingot has completely solidified and cooled to room temperature, the vacuum is broken, the ingot is removed from the furnace, and the tin alloy target is removed from the mold 19, or at this time the metallurgical bonding with the back plate has been completed.

[0021] Reference Figures 2-8A tin alloy target casting device, applied to a tin alloy target casting method for suppressing shrinkage cavities and component segregation as described above, includes a vacuum induction melting furnace 1. A feed box 3 is provided at the top of the vacuum induction melting furnace 1. An external pipe 5 is fixedly connected to the outside of the vacuum induction melting furnace 1. An external furnace 10 is provided at the bottom end of the external pipe 5. A melting furnace 14 is provided inside the vacuum induction melting furnace 1. A mold 19 is provided inside the external furnace 10. A pressure-assisted solidification assembly 11 is provided at the top of the mold 19. The pressure-assisted solidification assembly 11 includes... Two symmetrical frames 1101 are provided, and a connecting frame 1102 is fixedly connected to one side of each symmetrical frame 1101. A sealing frame 1103 is fixedly connected to one side of one of the connecting frames 1102. A drive motor 1104 is installed inside the sealing frame 1103. The power output shaft of the drive motor 1104 is connected to a threaded rod 1105 through a coupling. The end of the threaded rod 1105 away from the drive motor 1104 is movably connected to the inside of the connecting frame 1102. Guide rods 1106 are fixedly connected to both sides of the inside of the other connecting frame 1102.

[0022] Reference Figures 5-7 In a preferred embodiment, movable seats 1107 are provided on the outer sides of both the threaded rod 1105 and the guide rod 1106. Slide groove holes are provided on the opposite sides of the two connecting frames 1102. The movable seats 1107 are movably connected to the inside of the slide groove holes. An internal frame 1108 is fixedly connected to the opposite side of the movable seats 1107. A servo motor 1109 is provided on the side of the internal frame 1108 near the sealing frame 1103. The power output shaft of the servo motor 1109 is connected to a rotating shaft 1110 through a coupling. The side of the rotating shaft 1110 away from the servo motor 1109 is movably connected to the inside of the internal frame 1108. A pulling rope 1111 is wound around the outer side of the rotating shaft 1110.

[0023] In this design, two spring rods 1112 are fixedly connected to the bottom of the built-in frame 1108. Pressure sealing discs 1113 are fixedly connected to the bottom of both the spring rods 1112 and the pulling rope 1111, and the pressure sealing discs 1113 are located directly above the mold 19.

[0024] Specifically, firstly, the drive motor 1104 inside the sealing frame 1103 starts, and the power output shaft drives the threaded rod 1105 to rotate through the coupling. Since the movable seat 1107 is threadedly engaged with the threaded rod 1105, and the movable seat 1107 is simultaneously fitted onto the outside of the guide rod 1106 inside the connecting frame 1102 on the other side, the rotation of the threaded rod 1105 is converted into linear movement of the movable seat 1107 along the guide rod 1106. At the same time, the movable seat 1107 slides along the sliding groove hole on the connecting frame 1102, thereby driving the entire internal frame 1108 between the movable seats 1107 to move, ultimately causing the pressure sealing disc 1113 at the bottom of the internal frame 1108 to move precisely above the mold opening 19. Subsequently, the servo motor 1109 on the side of the internal frame 1108 starts, and the power output shaft drives the rotating shaft 1110 to rotate through the coupling. The rotating shaft 1110 tightens the pull rope 1111 wound on the outside. 11. The pressure sealing disc 1113 is pulled downwards. The pressure sealing disc 1113 is made of silicon nitride ceramic with a 0.1mm thick boron nitride coating on the surface. The diameter is within ±0.1mm tolerance of the opening of the mold 19. The pressure sealing disc 1113 moves towards the opening of the mold 19. At the same time, the spring rod 1112 at the bottom of the built-in frame 1108 is stretched synchronously. When the pressure sealing disc 1113 is in contact with the top interface of the mold 19, the elastic rebound force of the spring rod 1112 and the pulling force of the pulling rope 1111 work together to apply a constant low-pressure mechanical pressure to the melt in the mold 19. The pressure range is 0.1-0.5MPa. The pressure closed-loop control is achieved through the current feedback of the servo motor 1109. When the pressure exceeds 0.6MPa, the machine stops automatically. The elastic coefficient of the spring rod 1112 is 500N / m, and the maximum stretch is ≤50mm, which forces the melt to shrink and compensate under pressure, thereby reducing internal shrinkage and increasing the density of the target blank. In specific application scenarios, the pressure sealing cake 1113 applies a constant low-pressure mechanical pressure to the melt inside the mold 19, forcing the melt to continuously shrink and compensate during the solidification process, directly filling the gaps formed by volume shrinkage, minimizing the generation of shrinkage cavities and porosity, and improving the internal density of the target material.

[0025] Reference Figure 5 and Figure 8 In a preferred embodiment, a directional thermal field control component 15 is provided on the outer side of the mold 19. The directional thermal field control component 15 includes a stand 1501. A vacuum motor 1502 is provided at the top of the stand 1501. The power output shaft of the vacuum motor 1502 is connected to a rotating rod 1503 through a coupling. Both ends of the rotating rod 1503 are movably connected to the inner side of the stand 1501. A guide threaded part 1509 is fixedly connected to the outer side of the rotating rod 1503.

[0026] In this design, a movable part 1505 is provided on the outer side of the guide threaded part 1509. A connector 1506 is fixedly connected to one side of the movable part 1505. Two straight rods 1504 are fixedly connected to the inner side of the upright 1501. The connector 1506 is movably connected to the outer side of the straight rods 1504. A ring frame 1507 is fixedly connected to the side of the connector 1506 away from the guide threaded part 1509.

[0027] In this design, a temperature control ring 1508 is provided on the inner side of the ring frame 1507, and an extension frame 1510 is fixedly connected to one side of the connector 1506. A temperature sensor 1511 is fixedly connected to the side of the extension frame 1510 near the temperature control ring 1508, and the temperature control ring 1508 is in contact with the outer side of the mold 19.

[0028] Specifically, firstly, the vacuum motor 1502 at the top of the stand 1501 starts, and the power output shaft drives the rotating rod 1503 to rotate inside the stand 1501 via a coupling. The guide threaded part 1509 on the outside of the rotating rod 1503 rotates along with it. Since the moving part 1505 is threadedly engaged with the guide threaded part 1509, and the connecting part 1506 on one side of the moving part 1505 is fitted onto the outside of the straight rod 1504 inside the stand 1501, the rotation of the guide threaded part 1509 is converted into the vertical linear movement of the connecting part 1506 along the straight rod 1504. As the connecting part 1506 moves, it drives the ring frame 1507 fixed on one side to move synchronously, so that the temperature control ring 1508 inside the ring frame 1507 precisely fits onto the outside of the mold 19. The temperature control ring 1508 adopts a combination design of partitioned electric heating elements (power 500-1000W) and water cooling channels, with a temperature control range of 50-300℃ and a temperature control accuracy of ± At 2℃, the temperature sensor 1511 fixed on the extension frame 1510 on the connector 1506 will monitor the temperature data of the mold 19 and the temperature control ring 1508 in real time and feed the data back to the temperature control ring 1508. The temperature control ring 1508 will automatically adjust the heating power or water flow rate according to the monitoring results of the temperature sensor 1511. The temperature sensor 1511 has a sampling frequency of 1Hz. When the monitored temperature deviates from the set temperature by more than 5℃, the temperature control ring 1508 will automatically adjust the heating power or water flow rate to achieve precise control of the temperature of different areas of the mold 19 by the gradient temperature field (temperature difference 5-10℃ / cm). By adjusting the heating / cooling power of each area, the cooling rate of different positions of the mold 19 is controlled, and a temperature field with a gradient change from one end to the other end is constructed. This guides the melt in the mold 19 to solidify sequentially along the direction of the temperature field, and concentrates the shrinkage cavities generated during the solidification process to the riser part of the final solidification, thus ensuring the compactness of the main body of the target blank. In specific application scenarios, the temperature control ring 1508 is used to gradient control the cooling rate of different areas of the mold 19, thereby constructing a directional temperature field, guiding the melt to solidify sequentially from one end to the other, concentrating shrinkage cavities and porosity at the riser, avoiding defects in the main body of the target billet, and significantly improving the density of the target material.

[0029] Reference Figures 2-5 In a preferred embodiment, a fence 2 is provided on the outside of the feed box 3. The fence 2 is fixedly connected to the top of the vacuum induction melting furnace 1 by bolts, and the gap between the fence 2 and the feed box 3 is ≤5mm. The top of the feed box 3 is provided with a feed inlet 4. An external pipe 5 is fixedly connected to the outside of the vacuum induction melting furnace 1. A placement rack 16 is fixedly connected to the bottom of the inner side of the vacuum induction melting furnace 1. Two movable racks 17 are provided at the top of the placement rack 16. The movable racks 17 slide with the guide rail of the placement rack 16 through a slider, with a sliding accuracy of ≤0.05mm. The top of the movable racks 17 is fixed. The top of the melting furnace 14 is fixedly connected to the top of the melting furnace 14, which is movably connected to the inner side of the placement rack 16. The top of the melting furnace 14 is provided with a pouring port 20. The inner side of the conveying shell 8 is fixedly connected to a linear guide rail 12, and the top of the linear guide rail 12 is provided with a pouring groove 13. The top of the conveying shell 8 is fixedly connected to a vacuum pipe 6. The inner side of the external furnace 10 is fixedly connected to an electromagnetic stirrer 18, and the mold 19 is located on the top of the electromagnetic stirrer 18. The outer side of the external furnace 10 is fixedly connected to a suction pipe 9. One end of the vacuum pipe 6 and the external furnace pipe 5 are both fixedly connected to a vacuum device 7.

[0030] Working principle: In the tin alloy target casting process, the raw material is first fed into the feed box 3 through the feed port 4. The raw material enters the melting furnace 14 inside the vacuum induction melting furnace 1. The melting furnace 14 melts the raw material into liquid metal by temperature control. Then, the liquid metal flows through the casting port at the top of the melting furnace 14 into the casting equipment on the linear guide rail 12 inside the conveying shell 8. The casting equipment moves along the linear guide rail 12 and injects the liquid metal into the mold 19 at the top of the electromagnetic stirrer 18 inside the external furnace 10. Throughout the process, the vacuum device 7 operates continuously. The vacuum device 7 uses a Roots-rotary vane vacuum pump group with an ultimate vacuum degree ≤5×10 -4 Pa, one vacuum gauge (measuring range 10) is installed in both the vacuum induction melting furnace 1 and the external furnace 10. 5 -10 -4The system monitors the vacuum level in real time and extracts air from the vacuum induction melting furnace 1, the conveying shell 8, and the external furnace 10 through the vacuum pipe 6, the external pipe 5, and the suction pipe 9 to maintain a full-process vacuum environment. If the system detects the infiltration of external air, the vacuum device 7 will immediately strengthen the pumping to prevent the liquid metal from oxidizing. During casting, the electromagnetic stirrer 18 is started simultaneously. The electromagnetic stirrer 18 has a stirring frequency of 5-50Hz, a magnetic field strength of 0.1-0.5T, and is suitable for target materials with a diameter of 50-200mm and a thickness of 5-20mm. The stirring rate is dynamically adjusted according to the viscosity of the melt (when the viscosity is 1-10mPa·s, the stirring frequency is 10-20Hz). A low-frequency rotating electromagnetic field is applied to the molten tin alloy in the mold 19, and the electromagnetic force drives the melt convection and forms an induced current to achieve simultaneous stirring and casting, ensuring uniform melt composition and temperature. After casting is completed, the pressure-assisted solidification component 11 is activated: the drive motor 1104 drives the threaded rod 1105 to rotate, causing the movable seat 1107 to move along the guide rod 1106, which in turn drives the inner frame 1108 to move as a whole, so that the pressure sealing disc 1113 is aligned with the top of the mold 19 opening; at the same time, the servo motor 1109 drives the rotating shaft 1110 to rotate, tightening the pulling rope 1111, causing the pressure sealing disc 1113 to move downward and fit with the top interface of the mold 19. With the help of the spring rod 1112, a constant low-pressure mechanical pressure is applied, forcing the melt to shrink and compensate, reducing internal shrinkage porosity and improving the density of the target blank; Then, the vacuum motor 1502 drives the rotating rod 1503 and the guide threaded part 1509 to rotate, causing the moving part 1505 to drive the connecting part 1506 to move up and down along the straight rod 1504, thereby allowing the temperature control ring 1508 inside the ring frame 1507 to fit against the outside of the mold 19; the temperature sensor 1511 monitors the temperature in real time, and the temperature control ring 1508 precisely adjusts the cooling rate and temperature field of each area of ​​the mold 19 according to the data, so as to realize the sequential solidification of the melt from one end to the other end, concentrate the shrinkage cavity to the riser part, and finally ensure the compactness of the target blank body.

[0031] 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 method for casting tin alloy targets to suppress shrinkage cavities and compositional segregation, characterized in that, Includes the following steps: S1. Based on the performance requirements of the target material, such as purity, electrical properties, and bonding strength with the backing plate, accurately calculate the ratio of tin to other alloying elements such as indium, silver, and antimony, or oxygen-free copper / aluminum backing plate. Remove oxides, oil, and impurities from the surface of the raw material. Common methods include mechanical grinding, pickling, and ultrasonic cleaning. Thoroughly dry the cleaned raw material to prevent moisture from being carried into the melt. Pickling involves immersing in a 5%-10% hydrochloric acid solution at room temperature for 15-20 minutes. Ultrasonic cleaning parameters are 300W power, 40kHz frequency, and 20 minutes. Drying is performed using 100℃ hot air circulation for 2 hours to ensure that the moisture content of the raw material is ≤0.05%. S2, Mold (19) preparation: If casting into an independent target material, a graphite mold (19) or a metal mold (19) is required. The mold (19) needs to be pre-coated with a layer of refractory coating, such as yttrium oxide or boron nitride, to prevent sticking and facilitate demolding. More commonly, tin alloy is directly cast onto a backing plate, such as oxygen-free copper or aluminum, to form a composite target material. The backing plate needs to undergo strict pretreatment. The backing plate pretreatment includes: ① mechanical polishing until the surface roughness Ra≤0.8μm; ② passivation with 5% nitric acid solution for 10min; ③ ultrasonic cleaning, with the same parameters as the raw material cleaning; ④ preheating and drying at 200℃. The acceptance standard is that there are no oxide spots on the surface of the backing plate and the oil residue is ≤5mg / m. S3. Preheating: Before casting, preheat the back plate to a certain temperature, such as 200-300°C, to remove the gas adsorbed on the surface and reduce the temperature difference with the molten alloy, preventing poor bonding and rapid cooling. Load the pretreated raw materials into the vacuum induction melting furnace (1), which is usually made of graphite or ceramic. Close the furnace door and evacuate the furnace cavity to a high vacuum, such as 10°C. -2 Pa~10 -3 Pa, to remove oxygen, nitrogen and water vapor adsorbed in the furnace and raw materials to the maximum extent; S4. Melting and Refining: Under vacuum or with the protection of an inert gas such as argon, the raw materials are heated and melted at a rate of 5-10℃ / min. After melting, the material is held at this temperature for 30-60 minutes. The argon flow rate is 0.5-1L / min. The impurity control index is lead ≤0.001% and bismuth ≤0.0005%, verified by ICP-MS. In an induction furnace, the alloy composition is homogenized by electromagnetic induction. The material is held in a molten state for a period of time to allow low-melting-point impurities to volatilize and to promote the floating of gases and inclusions. S5. Casting: When the melt reaches the preset, precisely controlled superheat temperature above the liquidus, the molten alloy liquid is poured steadily and continuously into the crystallizer or mold with a pre-set back plate or mold (19) using a casting device. In order to obtain a dense and uniform microstructure, the ingot after casting needs to be cooled under controlled conditions. The cooling rate is adjusted according to the thickness of the target material: when the thickness is 5-10 mm, the cooling rate is 2-5℃ / min; when the thickness is 10-20 mm, the cooling rate is 1-2℃ / min. Gradient cooling is achieved through the directional thermal field control component to obtain fine grains. S6. Demolding: After the ingot has completely solidified and cooled to room temperature, the vacuum is broken and the ingot is taken out of the furnace. The tin alloy target is taken out of the mold (19), or the metallurgical bonding with the back plate has been completed at this time.

2. A tin alloy target casting apparatus, applied to a tin alloy target casting method for suppressing shrinkage cavities and compositional segregation as described in claim 1, comprising a vacuum induction melting furnace (1), characterized in that, The vacuum induction melting furnace (1) is provided with a feeding box (3) at the top. An external pipe (5) is fixedly connected to the outside of the vacuum induction melting furnace (1). An external furnace (10) is provided at the bottom end of the external pipe (5). A melting furnace (14) is provided inside the vacuum induction melting furnace (1). A mold (19) is provided on the inside of the external furnace (10). A pressure-assisted solidification assembly (11) is provided at the top of the mold (19). The pressure-assisted solidification assembly (11) includes two symmetrical frames (1101). The symmetrical frames (1101) are on opposite sides. Each is fixedly connected to a connecting frame (1102), and a sealing frame (1103) is fixedly connected to one side of one of the connecting frames (1102). A drive motor (1104) is installed inside the sealing frame (1103). The power output shaft of the drive motor (1104) is connected to a threaded rod (1105) through a coupling. The end of the threaded rod (1105) away from the drive motor (1104) is movably connected to the inside of the connecting frame (1102). Guide rods (1106) are fixedly connected to both sides inside the other connecting frame (1102).

3. The tin alloy target casting equipment according to claim 2, characterized in that, The threaded rod (1105) and guide rod (1106) are both provided with movable seats (1107) on their outer sides. The two connecting frames (1102) are provided with sliding groove holes on their opposite sides. The movable seats (1107) are movably connected to the inside of the sliding groove holes. The movable seats (1107) are fixedly connected to the opposite side of the inner frame (1108). The inner frame (1108) is provided with a servo motor (1109) on the side near the sealing frame (1103). The power output shaft of the servo motor (1109) is connected to a rotating shaft (1110) through a coupling. The side of the rotating shaft (1110) away from the servo motor (1109) is movably connected to the inner side of the inner frame (1108). The outer side of the rotating shaft (1110) is wrapped with a pulling rope (1111).

4. The tin alloy target casting equipment according to claim 3, characterized in that, The bottom end of the built-in frame (1108) is fixedly connected to two spring rods (1112). The bottom ends of the spring rods (1112) and the pulling rope (1111) are both fixedly connected to pressure sealing discs (1113). The pressure sealing discs (1113) are located directly above the mold (19). The pressure sealing discs are made of silicon nitride ceramic material and coated with a 0.1mm thick boron nitride coating. The diameter of the discs is within ±0.1mm of the mold opening. The pressure applied to the melt inside the mold is in the range of 0.1-0.5MPa.

5. The tin alloy target casting equipment according to claim 2, characterized in that, The mold (19) is provided with a directional thermal field control component (15) on its outer side. The directional thermal field control component (15) includes a stand (1501). A vacuum motor (1502) is provided at the top of the stand (1501). The power output shaft of the vacuum motor (1502) is connected to a rotating rod (1503) through a coupling. Both ends of the rotating rod (1503) are movably connected to the inner side of the stand (1501). A guide threaded part (1509) is fixedly connected to the outer side of the rotating rod (1503).

6. The tin alloy target casting equipment according to claim 5, characterized in that, A movable part (1505) is provided on the outer side of the guide threaded part (1509). A connector (1506) is fixedly connected to one side of the movable part (1505). Two straight rods (1504) are fixedly connected to the inner side of the stand (1501). The connector (1506) is movably connected to the outer side of the straight rod (1504). A ring frame (1507) is fixedly connected to the side of the connector (1506) away from the guide threaded part (1509).

7. The tin alloy target casting equipment according to claim 6, characterized in that, A temperature control ring (1508) is provided on the inner side of the ring frame (1507). An extension frame (1510) is fixedly connected to one side of the connector (1506). A temperature sensor (1511) is fixedly connected to the side of the extension frame (1510) near the temperature control ring (1508). The temperature control ring (1508) is in contact with the outer side of the mold (19). The temperature control ring adopts a combination structure of partitioned electric heating element (power 500-1000W) and water cooling channel. The temperature control range is 50-300℃ and the temperature control accuracy is ±2℃.

8. The tin alloy target casting equipment according to claim 2, characterized in that, The feed box (3) is provided with a fence (2) on the outside. The fence (2) is fixedly connected to the top of the vacuum induction melting furnace (1) by bolts. The gap between the fence (2) and the feed box (3) is ≤5mm. The top of the feed box (3) is provided with a feed inlet (4). The vacuum induction melting furnace (1) is fixedly connected with an external pipeline (5).

9. A tin alloy target casting device according to claim 8, characterized in that, The vacuum induction melting furnace (1) has a fixedly connected placement frame (16) at the bottom inner side. The top of the placement frame (16) is provided with two movable frames (17). The movable frames (17) slide with the guide rail of the placement frame (16) through a slider. The sliding accuracy is ≤0.05mm. The top of the movable frames (17) is fixedly connected to the top of the melting furnace (14). The melting furnace (14) is movably connected to the inner side of the placement frame (16). The top of the melting furnace (14) is provided with a pouring port (20).

10. A tin alloy target casting device according to claim 9, characterized in that, A linear guide rail (12) is fixedly connected to the inner side of the conveying shell (8). A casting groove (13) is provided at the top of the linear guide rail (12). A vacuum pipe (6) is fixedly connected to the top of the conveying shell (8). An electromagnetic stirrer (18) is fixedly connected to the inner side of the external furnace (10), and a mold (19) is located at the top of the electromagnetic stirrer (18). A suction pipe (9) is fixedly connected to the outer side of the external furnace (10). A vacuum device (7) is fixedly connected to one end of both the vacuum pipe (6) and the external furnace pipe (5). The vacuum device is a Roots-rotary vane vacuum pump group with an ultimate vacuum degree ≤5×10 -4 Pa, one vacuum gauge (measuring range 10) is installed in both the vacuum induction melting furnace and the external furnace. 5 -10 - 4 (Pa), used to monitor the vacuum level inside the furnace in real time.

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