Tubular target material and preparation method thereof

Abstract

The invention provides a preparation method of a tubular target material. The preparation method comprises the following steps: preparing a tube target blank in which the target material and a back tube are integrally bound through hot isostatic pressing, processing a connecting thread and a brazing surface at the position of the back tube, coating brazing filler metal after the brazing surface is treated, performing multi-stage splicing on the tube blank, performing brazing, and finally machining to obtain a finished product tube target. According to the technical process, large-area brazing binding between the target material and the back pipe is avoided, the pipe target quality is improved, the length of the target material is free and controllable, the requirements of magnetron sputtering pipe targets in various industries can be met, batch production can be achieved, and the application prospect is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of magnetron sputtering target materials, and in particular relates to a tubular target material and a preparation method thereof. Background Art

[0002] Magnetron sputtering is a physical vapor deposition (PVD) film-forming technology with the advantages of fast film-forming rate, large coating area, wide application range and low energy consumption. The coated layer has the advantages of high quality, good uniformity and controllable thickness. During magnetron sputtering, the magnetic field of the cathode target is maintained by a permanent magnet. Currently, two types of permanent magnets, planar and rod-shaped, are commonly used in industry. Planar permanent magnets form a racetrack-shaped magnetic field with planar targets, while rod-shaped magnets form a circumferential magnetic field on the surface of tubular targets. Only the target material at the above magnetic field is sputtered away from the target surface. Therefore, the utilization rate of planar targets is less than 30%, while the utilization rate of tubular targets can be as high as 80% or more. At present, tubularization is an important development direction for magnetron sputtering targets.

[0003] The tube target is generally composed of a stainless steel back tube and an outer target material. At present, the manufacturing method of domestic magnetron sputtering tube targets is mainly plasma spraying, which has many shortcomings such as high oxygen content, low density, and poor uniformity of organization. Especially for some refractory metals, it is difficult to achieve a thicker target layer, and it is increasingly difficult to meet the increasingly stringent use requirements of downstream manufacturers. Relevant technicians in China have actively developed new tube target manufacturing technologies, and some related patents are shown in Table 1.

[0004] Table 1 Some tube target patents

[0005]

[0006]

[0007] Combined with relevant patents, it is found that some tube target manufacturing technologies often first prepare tube blanks through certain specific processes. The tube blanks exist independently and are not bound to the back tube. After the tube blanks are spliced, they are brazed and bound to the overall back tube over a large area to prepare tubular targets. The brazing area is large, and it is difficult to accurately control the welding quality. Some processes will introduce new impurities, affecting the purity of the target material, and the material utilization rate is not high. Summary of the invention

[0008] The object of the present invention is to provide a tubular target material and a preparation method thereof. The preparation method has strong versatility and can be suitable for the preparation of tubular targets of various material systems. The present invention adopts a hot isostatic pressing process to prepare a tube blank, realizes the binding of the target material and a back tube, splices the back tube with multi-stage threads, brazes and seals a small area at the splicing, and finally prepares the tubular target material by machining, thereby avoiding large-area brazing binding between the target material and the back tube, improving the quality of the tubular target material, and the length of the target material is freely controllable, which can meet the needs of magnetron sputtering tube targets in various industries.

[0009] The above-mentioned purpose of the present invention is mainly achieved through the following technical solutions:

[0010] A method for preparing a tubular target material, wherein the sheath of the tubular target material comprises an outer sheath, a back tube, a welding ring and a target material layer, wherein the welding ring and the target material layer are arranged between the outer sheath and the back tube, and specifically comprises the following steps:

[0011] (1) Loading raw material powder into the target layer;

[0012] (2) thermally degassing the package obtained in step (1), and then hot isostatic pressing;

[0013] (3) machining the sheath obtained in step (2) to remove the welding ring, and providing an internal thread and an internal welding surface at one end of the back tube and an external thread and an external welding surface at the other end;

[0014] (4) After surface treatment of the inner welding surface and the outer welding surface, the surface is covered with brazing material to obtain a tubular target blank;

[0015] (5) threading the N tubular target material blanks obtained in step (4) in sequence using internal threads and external threads to obtain a tubular target material, where N is a positive integer;

[0016] (6) brazing the inner welding surface and the outer welding surface of the tubular target material obtained in step (5);

[0017] (7) Machining the tubular target blank obtained in step (6) to obtain a finished tubular target.

[0018] The raw material powder in step (1) is composed of at least one of a single substance powder, an alloy powder and a compound powder, and has a relative tap density of ≥55%.

[0019] A binding layer is arranged on the outer surface of the back tube. The binding layer is a single layer of Cu, Ni, Ag, Ti or a composite layer composed of two or more single layers. The binding layer is prepared by spraying or electroplating and has a thickness of 0.01 to 2 mm.

[0020] The thermal degassing process parameters of step (2) are as follows: temperature 300-1000°C, time 5-10h, vacuum degree ≤2×10 - 3 Pa.

[0021] The hot isostatic pressing process parameters of step (2) are temperature 400-1400° C., time 2-5 h, and pressure 100-150 MPa. After hot isostatic pressing, the binding rate between the target layer and the back tube is ≥99%, and the inner diameter deviation of the back tube is ≤1 mm.

[0022] The tooth widths of the internal and external threads are equal, being 1.5 to 2 mm, and the axial length of the threads is 1% to 7% of the total length of the back tube after machining.

[0023] The radial gap width between the inner welding surface and the outer welding surface is 0.2-1 mm, and the axial length between the inner welding surface and the outer welding surface is 10-30 mm.

[0024] The surface treatment method of the inner welding surface and the outer welding surface in step (4) is grinding, pickling or electroplating; the electroplating coating medium is a Cu, Ni, Ag single layer or a composite layer composed of two or more of the single layers, with a thickness of 5 to 15 μm.

[0025] The solder is one of In single substance, In-based solder, Sn single substance or Sn-based solder.

[0026] The N tubular target material blanks, the tubular target material blanks at the first and last stages are processed with internal threads and internal welding surfaces or external threads and external welding surfaces only at one end, and the blanks at the middle stage are processed with internal threads, internal welding surfaces, external threads and external welding surfaces at both ends respectively.

[0027] The process conditions of the brazing process in step (6) are as follows: welding is performed using a tube target brazing device, the tube target brazing device comprising an ultrasonic transmitting probe, a temperature sensor and a heating coil; the tubular target material is placed vertically so that the inner welding surface and the outer welding surface are located above the inner thread and the outer thread, the ultrasonic transmitting probe moves circumferentially along the outer cylindrical surface at the welding position, and the welding parameters are a temperature of 180 to 500° C., a time of 15 to 45 min, an ultrasonic transmitting probe (10) speed of 100 to 150 cm / min, an ultrasonic frequency of 20 to 300 KHz, and a back tube leakage rate of ≤1.0×10 -9 Pa·m 3 / S 1 .

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] (1) The present invention adopts threaded connection of tubular target blanks, and a small area of ​​brazing and sealing at the joints is performed, thereby avoiding large-area brazing binding between the target and the backing tube, and improving the quality of the tubular target.

[0030] (2) The present invention realizes densification by combining hot isostatic pressing diffusion bonding technology, while avoiding large-area brazing bonding between the target material and the back tube. The target material length is freely controllable, which can meet the needs of magnetron sputtering tube targets in various industries, can realize mass production, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the hot isostatic pressing package structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the tube blank splicing position structure of the present invention;

[0033] Figure 3 It is a schematic diagram of low temperature brazing of the back tube of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0035] The method for preparing the tubular target material of the present invention comprises the following steps:

[0036] 1. Package design and production

[0037] Figure 1 The figure shows a schematic diagram of the hot isostatic pressing sheath structure of the present invention, which is composed of an outer sheath 1, a back tube 2, a welding ring 3 and a binding layer 4. The size of the sheath should be designed based on the type of raw material powder used, the tap density, the hot isostatic pressing temperature and the size of the finished product, so that the size of the back tube 2 after hot isostatic pressing can meet the requirements of the finished product, and the inner diameter deviation of the back tube 2 is ≤1mm; the material of the binding layer 4 should be selected according to the type of powder, and its material is a single layer of Cu, Ni, Ag, Ti or a composite layer composed of two or more single layers, which is attached to the outer surface of the back tube 2 by electroplating or spraying, with a thickness of 0.01 to 2mm, so that the target material is bound to the back tube 2 while being hot isostatically compacted, and the bonding rate is ≥99%.

[0038] 2. Powder filling and thermal degassing

[0039] The raw material powder of the present invention can be a single substance powder, alloy powder, compound powder or a mixed powder of two or more powders composed of the former. The powder particle size can be regulated and proportioned so that the relative tap density of the powder is ≥55%, which can reduce the deformation of the package during the hot isostatic pressing process and is conducive to controlling the straightness of the tube target. The powder is loaded into the tubular gap in the hot isostatic pressing package, tapped and tapped, and then sealed and welded for thermal degassing. The process is 300-1000°C, 5-10h, and the vacuum degree is ≤2×10 -3 Pa, but the specific process should be determined according to the type of raw material powder.

[0040] 3. Hot Isostatic Pressing

[0041] The hot isostatic pressing process of the present invention is performed at a temperature of 400 to 1400° C., for 2 to 5 hours, and under a pressure of 100 to 150 MPa, but the specific process should be determined according to the type of raw material powder.

[0042] 4. Tube Processing

[0043] like Figure 2The figure shows the schematic diagram of the splicing position structure of the tube blank of the present invention. The tube blank processing of the present invention refers to removing the welding rings 3 on both sides of the tube blank after hot isostatic pressing, processing the threads and welding surfaces on the back tube 2 as required, and splicing in multiple stages. The blanks at the first and last stages are processed with internal threads 6, internal welding surfaces 7 or external threads 8, and external welding surfaces 9 at only one end, and the blanks at the middle stage are processed with internal threads 6, internal welding surfaces 7 and external threads 8, and external welding surfaces 9 at both ends. The internal threads 6 and external threads 8 have the same thread width, which is 1.5 to 2 mm, and the axial length of the threads is 1% to 7% of the total length of the single back tube 2 after machining. The radial gap width of the internal welding surface 7 and the external welding surface 9 is 0.2 to 1 mm, and the axial length of the welding surface is 10 to 30 mm.

[0044] 5. Low temperature brazing

[0045] like Figure 3 The figure shows a schematic diagram of low-temperature brazing of the back tube of the present invention. The multi-stage spliced ​​tubular target back tube 2 is welded by brazing equipment, and the brazing equipment includes an ultrasonic transmitter probe 10, a temperature sensor 11 and a heating coil 12. In the low-temperature brazing of the present invention, the multi-stage spliced ​​tube blank should be placed vertically, and the welding surface should be ensured to be above the thread at any position. The welding surface should be treated before brazing, and the treatment method can be grinding, pickling or electroplating. If electroplating treatment is used, the coating medium is a single layer of Cu, Ni, Ag or a composite layer composed of two or more single layers, with a thickness of 5 to 15 μm. The brazing material can be In and In-based brazing material or Sn and Sn-based brazing material. The brazing process is a temperature of 180 to 500 ° C, a time of 15 to 45 minutes, and at the same time, the ultrasonic transmitter probe moves circumferentially along the outer cylindrical surface at the welding position, with a speed of 100 to 150 cm / min and an ultrasonic frequency of 20 to 300 KHz. The leakage rate of the back tube after brazing is ≤1.0×10 -9 Pa·m 3 / S 1 .

[0046] 6. Tube finishing

[0047] The tube finishing process of the present invention refers to finishing the tube blank after multi-stage splicing and brazing into a finished tube target as required.

[0048] Example 1

[0049] This example provides a specification of A method for preparing a Ti50Al50at% tube target in the form of an end clip, in this embodiment, N=3, and the preparation method comprises the following contents:

[0050] Using Ti and Al powders as raw materials, the laser particle size of Ti powder is D10 = 14μm, D50 = 23μm, D90 = 44μm, and the laser particle size of Al powder is D10 = 17μm, D50 = 29μm, D90 = 55μm. The relative tap density of the two powders after mixing at a ratio of Ti50Al50at% is 58.21%. The size of the hot isostatic pressing package is The outer surface of the stainless steel back tube 2 is electroplated with Cu, with a thickness of 0.15 mm. The Ti50Al50at% mixed powder is filled into the sleeve and tapped to compact. The sleeve after powder filling is sealed and hot degassed, with a process temperature of 350°C, a time of 5h, and a vacuum degree of ≤2×10 -3 The degassed package is hot isostatically pressed at a temperature of 450°C, a time of 3 hours, and a pressure of 120 MPa. The inner diameter of the back tube 2 after hot isostatic pressing is still After hot isostatic pressing, the carbon steel welding ring 3 is removed from the tube blank, and the three tube blanks are processed as a whole to 1098mm, 1077mm and 1071mm in length respectively. Then the stainless steel back tube 2 is processed as follows: one side of the 1098mm long tube blank is processed with external thread 8 and external welding surface 9; one side of the 1077mm long tube blank is processed with external thread 8 and external welding surface 9, and the other side is processed with internal thread 6 and internal welding surface 7; one side of the 1071mm long tube blank is processed with internal thread 6 and internal welding surface 7. The major diameter of the internal and external threads is The tooth width is 1.5mm, the axial length is 40mm, and the outer welding surface is 9mm in diameter. Inner welding surface 7 diameter The axial length is 12mm. After processing, the inner and outer welding surfaces are electroplated with Ni with a thickness of 10μm.

[0051] The brazing material selected in this embodiment is In foil with a thickness of 0.2 mm. The In foil is wrapped around the surface of the outer welding surface 9. Three tube blanks are spliced ​​together with threads and placed vertically. The 1098 mm long tube blank is located at the bottom layer, the 1077 mm long tube blank is located in the middle layer, and the 1071 mm long tube blank is located at the top layer. The welding surfaces at the two splicing positions are both located above the threads, and the In foil is clamped in the gap between the inner and outer welding surfaces. The heating coil 12 and the temperature sensor 11 are placed at the two splicing positions for low-temperature brazing. At the same time, the ultrasonic transmitting probe 10 moves circumferentially on the outer surface of the splicing position. The process is a temperature of 180°C, a time of 25 minutes, a probe frequency of 75 KHz, and a probe moving speed of 100 cm / min. After brazing, it is finely processed into a finished target material.

[0052] Example 2

[0053] This example provides a specification of A method for preparing a W tube target with a threaded end, in this embodiment, N=2, and the preparation method comprises the following contents:

[0054] In this example, W single powder is used as raw material. The laser particle size of W powder is D10 = 51μm, D50 = 89μm, D90 = 153μm, and its relative tap density is 63.27%. The size of the hot isostatic pressing package is The outer surface of the stainless steel back tube 2 is electroplated with a Cu / Ni layer, with a bottom Cu layer thickness of 0.05 mm and an upper Ni layer thickness of 0.15 mm. W powder is filled into the package and tapped to compact it. The package after powder filling is sealed and hot degassed, with a process temperature of 950°C, a time of 7 hours, and a vacuum degree of ≤2×10 -3 Pa. The degassed sheath is hot isostatically pressed at a temperature of 1250°C, a time of 4 hours, and a pressure of 135 MPa. After hot isostatic pressing, the inner diameter of the back tube 2 shrinks to 56 mm. After hot isostatic pressing, the carbon steel welding ring 3 is removed from the tube blank, and the two tube blanks are processed as a whole to 1100 mm and 1135 mm in length, respectively. The stainless steel back tube 2 is then processed as follows: one side of the 1100 mm long tube blank is processed with an internal thread 6 and an internal welding surface 7; one side of the 1135 mm long tube blank is processed with an external thread 8 and an external welding surface 9. The major diameters of the internal and external threads are both The tooth width is 1.5mm, the axial length is 45mm, and the outer welding surface is 9mm in diameter. Inner welding surface 7 diameter The axial length is 15 mm. After processing, the inner and outer welding surfaces are electroplated with Ag with a thickness of 15 μm.

[0055] The brazing material selected in this example is Sn foil with a thickness of 0.2 mm. The Sn foil is wrapped around the surface of the outer welding surface 9. Two tube blanks are spliced ​​by threads and placed vertically. The 1135 mm long tube blank is located in the lower layer, and the 1100 mm long tube blank is located in the upper layer. The welding surface at the splicing position is located above the threads. The Sn foil is clamped in the gap between the inner and outer welding surfaces. At the same time, the ultrasonic transmitting probe 10 moves circumferentially on the outer surface of the splicing position. The temperature is 280°C, the time is 35 minutes, the probe frequency is 105KHz, and the probe moving speed is 110cm / min. After brazing, it is finely processed into a finished target material.

[0056] Example 3

[0057] This example provides a specification of A method for preparing a Cr80Cu15Ag5wt% tube target in the form of an end clip, in this embodiment, N=2, and the preparation method comprises the following contents:

[0058] This embodiment uses Cr, Cu, and Ag powders as raw materials. The laser particle size of Cr powder is D10=7μm, D50=15μm, and D90=31μm. The laser particle size of Cu powder is D10=3μm, D50=6μm, and D90=11μm. The laser particle size of Ag powder is D10=1μm, D50=4μm, and D90=9μm. The relative tap density of the three powders after mixing at a ratio of Cr80Cu15Ag5wt% is 59.67%. The size of the hot isostatic pressing package is The outer surface of the stainless steel back tube 2 is electroplated with Ag, with a thickness of 0.2 mm. Cr80Cu15Ag 5wt% mixed powder is filled into the sleeve and tapped to compact. The sleeve after powder filling is sealed and hot degassed at 450°C for 5 hours and the vacuum degree is ≤2×10 -3 The degassed package is hot isostatically pressed at a temperature of 890°C, a time of 3 hours, and a pressure of 150 MPa. The inner diameter of the back tube 2 after hot isostatic pressing is still After hot isostatic pressing, the carbon steel welding ring 3 is removed from the tube blank, and the two tube blanks are processed to 1300mm and 1330mm in length. Then the stainless steel back tube 2 is processed as follows: the inner thread 6 and the inner welding surface 7 are processed on one side of the 1300mm long tube blank; the outer thread 8 and the outer welding surface 9 are processed on one side of the 1330mm long tube blank. The major diameters of the inner and outer threads are The tooth width is 1.2mm, the axial length is 50mm, and the outer welding surface is 9mm in diameter. Inner welding surface 7 diameter The axial length is 15mm. After processing, the inner and outer welding surfaces are polished clean.

[0059] The solder selected in this example is SnAgCu solder paste. The solder paste is applied to the inner and outer welding surfaces. Two tube blanks are spliced ​​with threads and placed vertically. The 1330mm long tube blank is located in the lower layer, and the 1300mm long tube blank is located in the upper layer. The welding surface at the splicing position is located above the threads, and the solder paste is clamped in the gap between the inner and outer welding surfaces. At the same time, the ultrasonic transmitting probe 10 moves circumferentially on the outer surface of the splicing position, with a temperature of 305°C, a time of 30min, a probe frequency of 110KHz, and a probe moving speed of 90cm / min. After brazing, it is finely processed into a finished target material.

[0060] Example 4

[0061] This embodiment provides a specification of A method for preparing a W90Ti10wt% tube target in the form of an end clip, in this embodiment, N=2, and the preparation method comprises the following contents:

[0062] In this embodiment, W and Ti powders are used as raw materials. The laser particle size of W powder is D10=23μm, D50=55μm, D90=86μm, and the laser particle size of Ti powder is D10=19μm, D50=44μm, D90=69μm. The relative tap density of the two powders after mixing at a ratio of W90Ti10wt% is 63.77%. The size of the hot isostatic pressing package is The outer surface of the stainless steel tube is electroplated with Ni, with a thickness of 0.3 mm. The W90Ti10wt% mixed powder is filled into the sleeve and tapped to compact. The sleeve after powder filling is sealed and hot degassed at a temperature of 900°C, a time of 5h, and a vacuum degree of ≤2×10 -3 The degassed package is hot isostatically pressed at a temperature of 980°C, a time of 3 hours, and a pressure of 150 MPa. The inner diameter of the back tube 2 after hot isostatic pressing is still After hot isostatic pressing, the carbon steel welding ring 3 is removed from the tube blank, and the two tube blanks are processed to 1500mm and 1535mm in length, respectively. Then, the stainless steel back tube 2 is processed as follows: one side of the 1500mm long tube blank is processed with internal thread 6 and internal welding surface 7; one side of the 1535mm long tube blank is processed with external thread 8 and external welding surface 9. The major diameter of the internal and external threads is The tooth width is 1.5mm, the axial length is 50mm, and the outer welding surface is 9mm in diameter. Inner welding surface 7 diameter The axial length is 15mm. After processing, the inner and outer welding surfaces are electroplated with Ni with a thickness of 10μm.

[0063] The brazing material selected in this example is Sn foil with a thickness of 0.2 mm. The Sn foil is wrapped around the outer welding surface. Two tube blanks are spliced ​​by threads and placed vertically. The 1535 mm long tube blank is located in the lower layer, and the 1500 mm long tube blank is located in the upper layer. The welding surface at the splicing position is located above the threads. The Sn foil is clamped in the gap between the inner and outer welding surfaces. At the same time, the ultrasonic transmitting probe 10 moves circumferentially on the outer surface of the splicing position. The process is 295°C, the time is 30 minutes, the probe frequency is 130KHz, and the probe moving speed is 135cm / min. After brazing, it is finely processed into a finished target material.

[0064] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0065] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for preparing a tubular target, characterized in that: The sheath of the tubular target material comprises an outer sheath (1), a back tube (2), a welding ring (3) and a target material layer (5), wherein the welding ring (3) and the target material layer (5) are arranged between the outer sheath (1) and the back tube (2), and specifically comprises the following steps: (1) Filling the raw material powder into the sheathed target layer (5); (2) thermally degassing the package obtained in step (1), and then hot isostatic pressing; (3) machining the sheath obtained in step (2) to remove the welding ring (3), and providing an internal thread (6) and an internal welding surface (7) at one end of the back tube (2) and an external thread (8) and an external welding surface (9) at the other end; (4) performing surface treatment on the inner welding surface (7) and the outer welding surface (9), and then covering them with brazing material to obtain a tubular target material blank; (5) using the internal thread (6) and the external thread (8) to sequentially thread the N tubular target material blanks obtained in step (4) to obtain a tubular target material, where N is a positive integer; (6) brazing the inner welding surface (7) and the outer welding surface (9) of the tubular target material obtained in step (5); (7) Machining the tubular target blank obtained in step (6) to obtain a finished tubular target.

2. The method for preparing a tubular target according to claim 1, characterized in that: The raw material powder in step (1) is composed of at least one of a single substance powder, an alloy powder and a compound powder, and has a relative tap density of ≥55%.

3. The method for preparing a tubular target according to claim 1, characterized in that: The outer surface of the back tube (2) is provided with a binding layer (4), which is a single layer of Cu, Ni, Ag, Ti or a composite layer composed of two or more single layers. The binding layer (4) is prepared by spraying or electroplating and has a thickness of 0.01 to 2 mm.

4. The method for preparing a tubular target according to claim 1, characterized in that: The thermal degassing process parameters of step (2) are as follows: temperature 300-1000°C, time 5-10h, vacuum degree ≤2×10 -3 Pa.

5. The method for preparing a tubular target according to claim 1, characterized in that: The hot isostatic pressing process parameters of step (2) are temperature 400-1400° C., time 2-5 hours, and pressure 100-150 MPa. After hot isostatic pressing, the binding rate between the target layer (5) and the back tube (2) is ≥99%, and the inner diameter deviation of the back tube is ≤1 mm.

6. The method for preparing a tubular target according to claim 1, characterized in that: The thread widths of the internal thread (6) and the external thread (8) are equal, being 1.5 to 2 mm, and the axial length of the thread is 1% to 7% of the total length of the back tube (2) after machining.

7. The method for preparing a tubular target according to claim 1, characterized in that: The radial gap width between the inner welding surface (7) and the outer welding surface (9) is 0.2 to 1 mm, and the axial length between the inner welding surface (7) and the outer welding surface (9) is 10 to 30 mm.

8. The method for preparing a tubular target according to claim 1, characterized in that: The surface treatment method of the inner welding surface (7) and the outer welding surface (9) in step (4) is grinding, pickling or electroplating; the electroplating treatment coating medium is a Cu, Ni, Ag single layer or a composite layer composed of two or more of the single layers, with a thickness of 5 to 15 μm.

9. The method for preparing a tubular target according to claim 1, characterized in that: The solder is one of In single substance, In-based solder, Sn single substance or Sn-based solder.

10. The method for preparing a tubular target according to claim 1, characterized in that: The N tubular target material blanks, the tubular target material blanks located at the first and last stages, are processed with internal threads (6) and internal welding surfaces (7) or external threads (8) and external welding surfaces (9) at only one end, and the blanks located at the middle stage are processed with internal threads (6), internal welding surfaces (7), external threads (8) and external welding surfaces (9) at both ends, respectively.

11. The method for preparing a tubular target according to claim 1, characterized in that: The process conditions of the brazing process in step (6) are as follows: welding is performed using a tube target brazing device, wherein the tube target brazing device comprises an ultrasonic transmitting probe (10), a temperature sensor (11) and a heating coil (12); the tubular target material is placed vertically so that the inner welding surface (7) and the outer welding surface (9) are located above the inner thread (6) and the outer thread (8); the ultrasonic transmitting probe (10) moves circumferentially along the outer cylindrical surface at the welding position; the welding parameters are a temperature of 180 to 500° C., a time of 15 to 45 min, a speed of the ultrasonic transmitting probe (10) of 100 to 150 cm / min, an ultrasonic frequency of 20 to 300 KHz, and a back tube leakage rate of ≤1.0×10 -9 Pa·m 3 / S 1 .

12. A tubular target, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 11.

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