Brazing method for graphite target material

Abstract

The invention relates to a graphite target material brazing method which comprises the following steps: (1) carrying out sand blasting on a welding surface of a graphite target material to obtain a sand-blasted graphite target material; (2) carrying out vacuum magnetron sputtering titanium plating on the welding surface of the graphite target material subjected to sand blasting to obtain a graphite target material with a titanium film; and (3) the back plate and the graphite target material with the titanium film are heated, and brazing is conducted on the heated graphite target material and the back plate. The graphite target material is subjected to sand blasting and vacuum magnetron sputtering titanium plating treatment, the problem that the wettability of the welding flux on the surface of the graphite target material is poor is solved, the risk of unsoldering in the using process of the graphite target material is greatly reduced, the production cost is reduced, the production efficiency of products is improved, meanwhile, the backboard and the graphite target material with the titanium film are brazed, and the quality of the products is improved. And the tensile strength of the graphite target material can be greatly improved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor electronic technology, and in particular to a brazing method for a graphite target material. Background Art

[0002] Graphite materials are widely used in nuclear reactors, aviation, aerospace structural materials, electrode materials, special-purpose drill bits, corrosion-resistant crucibles for chemical experiments, semiconductor materials, etc. due to their high temperature resistance, corrosion resistance, and self-lubrication. Graphite targets are generally used in the semiconductor field as substrates for silicon carbide in chips. Graphite targets need to be connected to the back plate by brazing and sputtered on the equipment together. Since the graphite surface has poor wettability with solder, the surface is not treated, and the welding bonding rate with the back plate is low, which can easily lead to the risk of desoldering during use.

[0003] Sputtering coating technology usually uses gas discharge to generate gas ionization. The positive ions bombard the cathode target at high speed under the action of the electric field, knocking out the atoms or molecules of the cathode target and flying to the surface of the substrate to be plated to deposit a thin film. At present, sputtering technologies include radio frequency sputtering, three-level sputtering and magnetron sputtering. Compared with other sputtering technologies, magnetron sputtering has a higher coating rate. Today, magnetron sputtering has become one of the mainstream coating technologies. With the rapid development of terminal application markets such as artificial intelligence, 5G technology, and consumer electronics, the market size of semiconductor chips is expanding, and the application scope of magnetron sputtering technology is becoming more and more extensive.

[0004] Brazing refers to a welding process in which the solder with a lower melting point than the welding part and the welding part are heated to the melting temperature of the solder at the same time, and the gap of the solid workpiece is filled with liquid solder to connect the metal materials. In the magnetron sputtering process, the target assembly prepared by brazing has a brazing layer connection structure that makes the target and back plate connection interface have good thermal conductivity, which can effectively improve the heat dissipation performance of the target assembly; moreover, after the magnetron sputtering is completed, the solder layer of the target and back plate can be melted at an appropriate temperature, so that the back plate can be reused, saving the preparation cost of the target.

[0005] CN117248203A discloses a method for binding a graphite target material to a back plate, wherein the graphite target material is subjected to sandblasting and chemical nickel plating treatment on the welding surface to improve the wettability of the graphite target material, and then the target material is bonded to the back plate by brazing to improve the welding strength between the target material and the back plate, thereby reducing the risk of desoldering during the use of the target material. However, the process of chemical nickel plating is relatively complicated and requires the use of specific equipment and chemical reagents, and its production cost is too high. At the same time, wastewater and waste gas are also generated during the chemical nickel plating process. If these wastes are not properly handled, they will have an adverse impact on the environment.

[0006] CN115770922A discloses a method for brazing a graphite target material. A metal film is arranged on the welding surface of the graphite target material to increase the wettability of the solder on the surface of the graphite target material. The graphite target material and the back plate are then brazed to improve the welding bonding rate between the graphite target material and the back plate, thereby avoiding cracking of the graphite target material caused by the brazing process. The welding surface of the graphite target material is not processed in any way, and a metal film is directly arranged on the welding surface, which may cause a risk of desoldering during subsequent use.

[0007] In summary, it is necessary to develop a graphite target brazing method to reduce the risk of desoldering during the use of the target. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a graphite target brazing method, which can effectively improve the welding bonding rate and welding strength of the graphite target, reduce the risk of desoldering during the use of the target and the production cost, and improve the production efficiency of the product.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for brazing a graphite target material, the method comprising the following steps:

[0011] (1) sandblasting the welding surface of the graphite target to obtain a sandblasted graphite target;

[0012] (2) performing vacuum magnetron sputtering titanium coating on the welding surface of the sandblasted graphite target to obtain a graphite target having a titanium film;

[0013] (3) The backing plate and the graphite target having the titanium film are heated separately, and the heated graphite target and the backing plate are brazed.

[0014] The present invention is aimed at graphite targets. Different from conventional metal or metal alloy targets, graphite targets are very difficult to weld to metal back plates or metal alloy back plates due to the high compatibility of their own materials with metal or metal alloy materials. In addition, the surface wettability of the graphite target to the solder is very poor, especially when only brazing technology is used without using hot isostatic pressing technology. It is very difficult to achieve efficient and high-strength welding between the graphite target and the back plate. In this regard, the present invention first performs sandblasting on the graphite target to enhance the roughness of the surface of the graphite target, and then uses vacuum magnetron sputtering titanium plating to make the titanium film firmly adhere to the surface of the graphite target, thereby improving the problem of poor solder wettability on the surface of the graphite target, and effectively improving the welding bonding rate and welding strength of the graphite target; further, the present invention first heats the graphite target and the back plate before brazing, so that the graphite target and the back plate can reach temperature balance before brazing, reduce the thermal stress caused by temperature difference in the welding process, thereby reducing the deformation caused by temperature difference in the welding process and improving the welding quality; through the combination of the above-mentioned specific steps, the present invention greatly reduces the risk of desoldering during the use of the graphite target, reduces the production cost, and improves the production efficiency of the product. At the same time, brazing the back plate and the graphite target with titanium film can greatly improve the tensile strength of the graphite target.

[0015] As a preferred technical solution of the present invention, the sandblasting pressure in step (1) is 0.3-0.4 MPa, for example, it can be 0.3 MPa, 0.32 MPa, 0.34 MPa, 0.36 MPa, 0.38 MPa or 0.4 MPa, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0016] Preferably, the sand mold for sandblasting is white corundum.

[0017] Preferably, the type of the white corundum includes any one of 24#, 46# or 60# or a combination of at least two of them, wherein typical but non-limiting combinations include: a combination of 24# and 46#, a combination of 24# and 60#, a combination of 46# and 60#, and a combination of 24#, 46# and 60#.

[0018] Preferably, the roughness of the welding surface of the sandblasted graphite target is 11-14 μm, for example, it can be 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm or 14 μm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0019] The present invention limits the roughness of the welding surface of the graphite target material after sandblasting to 11-14μm, so that the welding strength between the graphite target material and the back plate is optimized. If the roughness of the welding surface of the graphite target material after sandblasting is less than 11μm, the welding strength is low and there may be a risk of desoldering. If the roughness of the welding surface of the graphite target material after sandblasting is greater than 14μm, the welding strength is almost zero and there is a greater risk of desoldering.

[0020] As a preferred technical solution of the present invention, the vacuum degree of the vacuum magnetron sputtering titanium plating in step (2) is 4.0×10 -3 -8.0×10 -3 Pa, for example, can be 4.0×10 -3 Pa, 5.0×10 -3 Pa, 6.0×10 -3 Pa, 7.0×10 -3 Pa or 8.0×10 -3 Pa, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0021] Preferably, the sputtering voltage of the vacuum magnetron sputtering titanium plating is 80-120V, for example, it can be 80V, 90V, 100V, 110V or 120V, but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0022] Preferably, the sputtering current of the vacuum magnetron sputtering titanium plating is 10-30 mA, for example, it can be 10 mA, 15 mA, 20 mA, 25 mA or 30 mA, but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0023] The present invention ensures the thickness uniformity of the titanium film by limiting the sputtering voltage of vacuum magnetron sputtering titanium plating to 80-120V and the sputtering current to 10-30mA.

[0024] Preferably, the sputtering time of the vacuum magnetron sputtering titanium coating is 3-5 hours, for example, it can be 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0025] Preferably, the titanium coating thickness of the graphite target with titanium film is 2-5 μm, for example, it can be 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0026] The present invention can achieve the best wetting effect by limiting the thickness of the titanium coating to 2-5 μm, which is beneficial to subsequent welding. If the thickness of the titanium coating is less than 2 μm, it is not conducive to the wetting of the surface of the graphite target, thereby affecting the final welding result. If the thickness of the titanium coating is greater than 5 μm, the coating thickness is relatively large, which has little effect on the wetting of the surface of the graphite target, but will greatly increase the sputtering time and increase the production cost.

[0027] Preferably, the roughness of the titanium coating of the graphite target with titanium film is 10-12 μm, for example, 10 μm, 10.5 μm, 11 μm, 11.5 μm or 12 μm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0028] The present invention limits the roughness of the titanium coating layer of the graphite target material with titanium film to 10-12μm, so that the welding strength between the graphite target material and the back plate is optimized. If the roughness of the titanium coating layer of the graphite target material with titanium film is less than 10μm, the welding strength is low and there may be a risk of desoldering. If the roughness of the titanium coating layer of the graphite target material with titanium film is greater than 12μm, the welding strength is almost zero and there is a greater risk of desoldering.

[0029] As a preferred technical solution of the present invention, the material of the backplane in step (3) includes any one of Al, Cu or Mo or a combination of at least two of them, wherein typical but non-limiting combinations include: a combination of Al and Cu, a combination of Al and Mo, a combination of Cu and Mo, and a combination of Al, Cu and Mo.

[0030] Preferably, the target temperature of the heating is 200-220°C, for example, it can be 200°C, 205°C, 210°C, 215°C or 220°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0031] Preferably, the heating temperature rise rate is 2-5°C / min, for example, it can be 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0032] As a preferred technical solution of the present invention, the brazing in step (3) includes wetting, bonding, hot pressing and cooling in sequence.

[0033] As a preferred technical solution of the present invention, the infiltration includes placing the solder independently on the welding surface of the graphite target material with the titanium film and the welding surface of the back plate for infiltration.

[0034] Preferably, the infiltration method includes ultrasonic infiltration.

[0035] Preferably, the welding surface of the back plate is treated with a steel brush before the infiltration treatment.

[0036] Preferably, the wetting time of the welding surface of the graphite target with titanium film is 10-20 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0037] Preferably, the wetting time of the welding surface of the backplane is 10-15 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0038] Preferably, the material of the solder includes indium solder.

[0039] In the present invention, because the material of the solder includes indium solder, it is difficult to wet the surface of the graphite target material, so it is necessary to first adopt sandblasting and titanium plating processes to improve the wetting effect.

[0040] As a preferred technical solution of the present invention, the bonding includes making a solder groove on the welding surface of the back plate, placing a copper wire in the solder groove, and then bonding the welding surface of the graphite target and the welding surface of the back plate.

[0041] Preferably, the depth of the solder groove is 3-5 mm, for example, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0042] Preferably, the length and width of the solder groove are the same as those of the back plate.

[0043] The present invention can ensure the welding bonding rate of the welding process by limiting the specific size of the solder groove. If the size of the solder groove is too small, too little solder is used, which is not conducive to subsequent welding and will reduce the welding bonding rate. If the size of the solder groove is too large, too much solder is used, and it is not easy to remove the solder after welding, which will increase labor costs.

[0044] Preferably, the diameter of the copper wire is 0.2-0.5 mm, for example, it can be 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm or 0.5 mm, but it is not limited to the listed values, and other values ​​not listed in the above numerical range are also applicable.

[0045] As a preferred technical solution of the present invention, the hot pressing includes placing a buffer pad on the bonded graphite target material, and placing a pressing block on the buffer pad.

[0046] Preferably, the temperature of the buffer pad is 200-220°C, for example, 200°C, 205°C, 210°C, 215°C or 220°C, but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0047] Preferably, the buffer pad comprises a silicone pad or a wooden block.

[0048] Preferably, the pressure of the pressing block is 0.3-0.5 MPa, for example, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa or 0.5 MPa, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0049] As a preferred technical solution of the present invention, the target temperature of cooling is 25°C.

[0050] Preferably, the cooling rate is 1-2°C / min, for example, it can be 1°C / min, 1.2°C / min, 1.4°C / min, 1.6°C / min, 1.8°C / min or 2°C / min, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0051] The present invention can ensure the welding strength between the graphite target material and the back plate by limiting the cooling rate to 1-2°C / min. If the cooling rate is less than 1°C / min, the cooling rate is too small, the cooling time is increased, and the production cost is increased. If the cooling rate is greater than 2°C / min, the cooling rate is too large, the temperature difference between the target material and the heating table is large, and deformation may occur. At the same time, for brittle target materials, the target material may crack due to deformation.

[0052] As a preferred technical solution of the present invention, the brazing method comprises the following steps:

[0053] (1) using white corundum to sandblast the welding surface of the graphite target, the pressure of the sandblasting is 0.3-0.4 MPa, and a graphite target with a roughness of 11-14 μm is obtained;

[0054] (2) At 4.0×10 -3 -8.0×10 -3 The welding surface of the sandblasted graphite target is subjected to vacuum magnetron sputtering titanium coating at a vacuum degree of 1.5 Pa, the thickness of the titanium coating layer is 2-5 μm, and a graphite target with a titanium film having a roughness of 10-12 μm is obtained;

[0055] (3) The back plate and the graphite target with titanium film are heated to the target temperature of 200-220°C at a heating rate of 2-5°C / min, respectively, and then molten solder is placed on the welding surface of the graphite target with titanium film, and the welding surface of the graphite target is infiltrated with an ultrasonic welding machine for 10-20 minutes; a manual steel brush and an ultrasonic welding machine are used to infiltrate the back plate for 10-15 minutes, and then a solder groove with a depth of 3-5mm is made on the welding surface of the back plate, and a copper wire with a diameter of 0.2-0.5mm is placed in the solder groove, and then the welding surface of the graphite target and the welding surface of the back plate are bonded, and a buffer pad is placed on the bonded graphite target, and a pressure block with a pressure of 0.3-0.5MPa is placed on the buffer pad. After the welding is completed, the welded graphite target and the back plate are cooled to 25°C at a cooling rate of 1-2°C / min, and then the pressure block is removed, and the brazing of the graphite target and the back plate is completed.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects:

[0057] The present invention performs sandblasting and vacuum magnetron sputtering titanium plating treatment on the graphite target material, so that the titanium film is firmly attached to the surface of the graphite target material, the problem of poor solder wettability on the surface of the graphite target material is improved, and the welding bonding rate of the graphite target material and the back plate obtained by brazing reaches more than 99.6%, and the bonding strength can reach more than 8.3MPa. At the same time, the problem of desoldering during the use of the graphite target material is solved, the production cost is reduced, and the production efficiency of the product is improved. At the same time, the back plate and the graphite target material with the titanium film are brazed, which can greatly improve the tensile strength of the graphite target material. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flow chart of the graphite target and back plate brazing process in Example 1 of the present invention. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0060] Example 1

[0061] This embodiment provides a method for brazing a graphite target. Figure 1 , the brazing method comprises the following steps:

[0062] (1) The surface of the graphite target to be sandblasted was wiped with ethanol and blown dry, and then the welding surface of the graphite target was sandblasted with 24# white corundum. The pressure of the sandblasting was 0.35 kPa, and a graphite target with a roughness of 12 μm was obtained;

[0063] (2) At 6.0×10 -3 The welding surface of the sandblasted graphite target is subjected to vacuum magnetron sputtering titanium coating at a vacuum degree of 1.5 Pa, wherein the sputtering voltage of the vacuum magnetron sputtering titanium coating is 100 V, the sputtering current is 20 mA, the sputtering time is 4 h, and the thickness of the titanium coating layer is 4 μm, thereby obtaining a graphite target with a titanium film having a roughness of 11 μm;

[0064] (3) The Al back plate and the graphite target with titanium film were heated to the target temperature of 210°C at a heating rate of 3°C / min, and molten solder was placed on the welding surface of the graphite target with titanium film, and the welding surface of the graphite target was infiltrated using an ultrasonic welding machine for 15 minutes; the Al back plate was infiltrated using a manual steel brush and an ultrasonic welding machine for 12 minutes, and then a solder groove with a depth of 4 mm was made on the welding surface of the Al back plate, and a copper wire with a diameter of 0.3 mm was placed in the solder groove, and then the welding surface of the graphite target and the welding surface of the Al back plate were bonded, and a 210°C silicone pad was placed on the bonded graphite target, and a pressure block with a pressure of 0.4 MPa was placed on the silicone pad. After welding, the welded graphite target and the Al back plate were cooled to 25°C at a cooling rate of 1.5°C / min, and then the pressure block was removed, and the brazing of the graphite target and the Al back plate was completed.

[0065] Example 2

[0066] This embodiment provides a method for brazing a graphite target, the method comprising the following steps:

[0067] (1) The surface of the graphite target to be sandblasted was wiped with ethanol and blown dry, and then the welding surface of the graphite target was sandblasted with 46# white corundum. The sandblasting pressure was 0.3 MPa, and a graphite target with a roughness of 11 μm was obtained;

[0068] (2) At 4.0×10 -3 The welding surface of the sandblasted graphite target is subjected to vacuum magnetron sputtering titanium plating at a vacuum degree of 1.5 Pa, wherein the sputtering voltage of the vacuum magnetron sputtering titanium plating is 80 V, the sputtering current is 30 mA, the sputtering time is 5 h, the thickness of the titanium plating layer is 5 μm, and a graphite target with a titanium film having a roughness of 10 μm is obtained;

[0069] (3) The Cu back plate and the graphite target with titanium film were heated to the target temperature of 200°C at a heating rate of 2°C / min, and molten solder was placed on the welding surface of the graphite target with titanium film, and the welding surface of the graphite target was infiltrated using an ultrasonic welding machine for 20 minutes; the Cu back plate was infiltrated using a manual steel brush and an ultrasonic welding machine for 15 minutes, and then a solder groove with a depth of 5 mm was made on the welding surface of the Cu back plate, and a copper wire with a diameter of 0.5 mm was placed in the solder groove, and then the welding surface of the graphite target and the welding surface of the Cu back plate were bonded, and a 200°C wooden block was placed on the bonded graphite target, and a pressure block with a pressure of 0.5 MPa was placed on the silicone pad. After welding, the welded graphite target and the Cu back plate were cooled to 25°C at a cooling rate of 1°C / min, and then the pressure block was removed, and the brazing of the graphite target and the back plate was completed.

[0070] Example 3

[0071] This embodiment provides a method for brazing a graphite target, the method comprising the following steps:

[0072] (1) The surface of the graphite target to be sandblasted was wiped with ethanol and blown dry, and then the welding surface of the graphite target was sandblasted with 60# white corundum. The sandblasting pressure was 0.4 MPa, and a graphite target with a roughness of 14 μm was obtained;

[0073] (2) At 8.0×10 -3 The welding surface of the sandblasted graphite target is subjected to vacuum magnetron sputtering titanium coating at a vacuum degree of 1.5 Pa, wherein the sputtering voltage of the vacuum magnetron sputtering titanium coating is 120 V, the sputtering current is 10 mA, the sputtering time is 3 h, the thickness of the titanium coating layer is 2 μm, and a graphite target with a titanium film having a roughness of 12 μm is obtained;

[0074] (3) The Mo back plate and the graphite target with titanium film are heated to the target temperature of 220°C at a heating rate of 5°C / min, and molten solder is placed on the welding surface of the graphite target with titanium film, and the welding surface of the graphite target is infiltrated with an ultrasonic welding machine for 10 minutes; the Mo back plate is infiltrated with a manual steel brush and an ultrasonic welding machine for 10 minutes, and then a solder groove with a depth of 3 mm is made on the welding surface of the Mo back plate, and a copper wire with a diameter of 0.2 mm is placed in the solder groove, and then the welding surface of the graphite target and the welding surface of the Mo back plate are bonded, and a 220°C silicone pad is placed on the bonded graphite target, and a pressure block with a pressure of 0.3 MPa is placed on the silicone pad. After welding is completed, the welded graphite target and the back plate are cooled to 25°C at a cooling rate of 2°C / min, and then the pressure block is removed, and the brazing of the graphite target and the back plate is completed.

[0075] Example 4

[0076] This embodiment provides a method for brazing a graphite target, which is the same as that of Embodiment 1 except that in step (2), the roughness of the titanium coating layer of the graphite target having a titanium film is adjusted to 6 μm.

[0077] Example 5

[0078] This embodiment provides a method for brazing a graphite target, which is the same as that of Embodiment 1 except that the roughness of the titanium coating layer of the graphite target with a titanium film in step (2) is adjusted to 14 μm.

[0079] Example 6

[0080] This embodiment provides a method for brazing a graphite target material, which is different from Embodiment 1 only in that, except for the step (3) in which the depth of the solder groove is adjusted to 2 mm, the rest is the same as Embodiment 1.

[0081] Example 7

[0082] This embodiment provides a method for brazing a graphite target, which is the same as that of Embodiment 1 except that the depth of the solder groove is adjusted to 6 mm in step (3).

[0083] Example 8

[0084] This embodiment provides a method for brazing a graphite target, which is the same as that of Embodiment 1 except that the cooling rate in step (3) is adjusted to 0.5°C / min.

[0085] Example 9

[0086] This embodiment provides a method for brazing a graphite target, which is the same as that of Embodiment 1 except that the cooling rate in step (3) is adjusted to 3°C / min.

[0087] Comparative Example 1

[0088] This embodiment provides a method for brazing a graphite target, which is different from the first embodiment only in that the sandblasting treatment in step (1) is not performed, and the rest is the same as the first embodiment.

[0089] Comparative Example 2

[0090] This embodiment provides a graphite target brazing method, which is the same as that of Embodiment 1 except that step (2) chemically titanium is plated on the welding surface of the sandblasted graphite target.

[0091] Comparative Example 3

[0092] This embodiment provides a method for brazing a graphite target. The only difference from Embodiment 1 is that the vacuum magnetron sputtering titanium plating treatment in step (2) is not performed. The rest is the same as Embodiment 1.

[0093] Comparative Example 4

[0094] This embodiment provides a method for brazing a graphite target, which is different from the first embodiment only in that, except for step (2) of performing vacuum magnetron sputtering nickel plating on the welding surface of the sandblasted graphite target, the rest is the same as the first embodiment.

[0095] The welding bonding rate and bonding strength of the graphite target material and the back plate obtained by brazing in the embodiment and the comparative example were tested. The welding bonding rate test was performed using an ultrasonic flaw detector; the bonding strength test method was a tensile strength test: the graphite target material obtained by brazing was processed into a hollow type with a hole depth to the welding joint, and then the graphite target material was suspended in the air and the pressure point of the pressure equipment with a digital display function was applied to the welding surface. The pressure during desoldering was recorded as the welding bonding strength of the material; and the surface of the graphite target material after brazing was observed to see if there were cracks. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] The test results show that:

[0099] (1) It can be seen from Examples 1-3 that the graphite target brazing method provided by the present invention performs sandblasting and vacuum magnetron sputtering titanium plating treatment on the graphite target so that the titanium film is firmly attached to the surface of the graphite target, thereby improving the problem of poor solder wettability on the surface of the graphite target, and making the welding bonding rate of the brazed graphite target and the back plate reach more than 99.6%, and the bonding strength can reach more than 8.3 MPa. At the same time, the problem of desoldering during the use of the graphite target is solved.

[0100] (2) Combining Example 1 and Examples 4-5, it can be seen that the roughness of the titanium coating of the graphite target with titanium film in step (2) of Example 1 is 11 μm, the welding bonding rate of the graphite target and the back plate in Example 1 is 99.8%, and the bonding strength is 9.5 MPa, while the roughness of the titanium coating of the graphite target with titanium film in Example 4 is 6 μm, the welding bonding rate of the graphite target and the back plate in Example 4 is 99.2%, and the bonding strength is 3.5 MPa, while the roughness of the titanium coating of the graphite target with titanium film in Example 5 is 14 μm, the welding bonding rate of the graphite target and the back plate in Example 5 is 99.0%, and the welding strength is 0.5 MPa. This shows that the present invention achieves the best welding strength between the graphite target and the back plate by controlling the roughness of the welding surface of the graphite target after sandblasting to 11-14 μm, and the bonding strength of the graphite target and the back plate obtained by brazing can reach above 8.3 MPa.

[0101] (3) It can be seen from Example 1 and Examples 6-7 that the depth of the solder groove in step (3) in Example 1 is 4 mm, the welding bonding rate of the graphite target and the back plate in Example 1 is 99.8%, and the bonding strength is 9.5 MPa, while the depth of the solder groove in Example 6 is 2 mm, the welding bonding rate of the graphite target and the back plate in Example 6 is 98.5%, and the bonding strength is 5.0 MPa, and the depth of the solder groove in Example 7 is 6 mm, the welding bonding rate of the graphite target and the back plate in Example 7 is 99.6%, and the bonding strength is 8.2 MPa. This shows that the present invention can ensure the welding bonding rate of the welding process by controlling the specific size of the solder groove. If the depth of the solder groove is too small, too little solder is used, which is not conducive to subsequent welding and will reduce the welding bonding rate. If the depth of the solder groove is too large, too much solder is used. Although it does not affect the welding bonding rate and bonding strength of the graphite target and the back plate, it is not easy to remove the solder after welding, which will increase labor costs.

[0102] (4) Combining Example 1 and Examples 8-9, it can be seen that the cooling rate of step (3) in Example 1 is 1.5°C / min, the welding bonding rate of the graphite target and the back plate in Example 1 is 99.8%, the bonding strength is 9.5MPa, and there is no crack on the surface of the graphite target after brazing, while the cooling rate in Example 8 is 0.5°C / min, the welding bonding rate of the graphite target and the back plate in Example 8 is 99.3%, the bonding strength is 8.1MPa, and there is no crack on the surface of the graphite target after brazing, and the cooling rate in Example 9 is 3°C / min, which is In Example 9, the welding bonding rate of the graphite target and the back plate is 99.1%, and the bonding strength is 8.4 MPa. There are cracks on the surface of the graphite target after brazing. This shows that the present invention can ensure the welding strength of the graphite target and the back plate by controlling the cooling rate to 1-2°C / min. If the cooling rate is too small, although it will not affect the welding bonding rate and bonding strength, the cooling time will increase, which increases the production cost. If the cooling rate is too large, the temperature difference between the target and the heating table will be large, and deformation may occur. At the same time, for brittle target materials, deformation may cause the target material to crack.

[0103] (5) It can be seen from Example 1 and Comparative Example 1 that the welding surface of the graphite target material in Comparative Example 1 was not sandblasted before titanium plating, and the welding surface roughness of the graphite target material was relatively small. The bonding strength between the graphite target material and the back plate obtained by brazing was only 0.3 MPa, and the graphite target material desoldered during use. This shows that the present invention enhances the roughness of the graphite target material surface by first sandblasting the graphite target material, so that the titanium film can be firmly attached to the surface of the graphite target material during the subsequent vacuum magnetron sputtering titanium plating treatment, thereby greatly reducing the risk of desoldering during the use of the graphite target material.

[0104] (6) It can be seen from Example 1 and Comparative Example 2 that in Comparative Example 2, the welding surface of the sandblasted graphite target is subjected to chemical titanium plating, and the bonding strength between the graphite target and the back plate obtained by brazing is only 1.0 MPa. This is because during the chemical titanium plating process, factors such as the stability, concentration, and temperature of the solution may affect the quality and bonding strength of the coating, and the process parameters are difficult to control. This shows that the present invention uses vacuum magnetron sputtering technology to plate titanium on the welding surface of the sandblasted graphite target, and the formed titanium plating layer has good uniformity, which can effectively improve the welding bonding rate and welding strength of the graphite target.

[0105] (7) It can be seen from Example 1 and Comparative Example 3 that in Comparative Example 3, the sandblasted graphite target is directly brazed to the back plate without vacuum magnetron sputtering titanium plating treatment. The welding bonding rate of the brazed graphite target and the back plate is 98.0%, and the bonding strength is only 0.2 MPa. At the same time, the graphite target desoldering occurs during use. This shows that the present invention performs vacuum magnetron sputtering titanium plating treatment on the sandblasted graphite target, so that the titanium film is firmly attached to the surface of the graphite target, thereby improving the problem of poor solder wettability on the surface of the graphite target, and effectively improving the welding bonding rate and welding strength of the graphite target, thereby greatly reducing the risk of desoldering during the use of the graphite target.

[0106] (8) It can be seen from Example 1 and Comparative Example 4 that in Comparative Example 4, the welding surface of the graphite target material after sandblasting is subjected to vacuum magnetron sputtering nickel plating treatment, and the welding bonding rate of the graphite target material and the back plate obtained by brazing is 99.2%, and the bonding strength is 3.5 MPa. This shows that the present invention forms a titanium plating layer of a certain thickness on the welding surface of the graphite target material by vacuum magnetron sputtering titanium plating treatment on the graphite target material after sandblasting. The titanium plating layer can improve the problem of poor solder wettability on the surface of the graphite target material, and effectively improve the welding bonding rate and welding strength of the graphite target material.

[0107] In summary, the present invention first performs sandblasting on the graphite target to enhance the roughness of the surface of the graphite target, and then uses vacuum magnetron sputtering titanium plating to make the titanium film firmly adhere to the surface of the graphite target, thereby improving the problem of poor solder wettability on the surface of the graphite target, and making the welding bonding rate of the brazed graphite target and the back plate reach more than 99.6%, and the bonding strength can reach more than 8.3MPa. At the same time, the problem of desoldering during the use of the graphite target is solved.

[0108] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for brazing a graphite target, characterized in that: The brazing method comprises the following steps: (1) sandblasting the welding surface of the graphite target to obtain a sandblasted graphite target; (2) performing vacuum magnetron sputtering titanium coating on the welding surface of the sandblasted graphite target to obtain a graphite target having a titanium film; (3) The backing plate and the graphite target having the titanium film are heated separately, and the heated graphite target and the backing plate are brazed.

2. The brazing method according to claim 1, characterized in that: The pressure of the sandblasting in step (1) is 0.3-0.4 MPa; Preferably, the sand type for sandblasting is white corundum; Preferably, the model of the white corundum includes any one of 24#, 46# or 60# or a combination of at least two; Preferably, the roughness of the welding surface of the graphite target after sandblasting is 11-14 μm.

3. The brazing method according to claim 1 or 2, characterized in that: The vacuum degree of the vacuum magnetron sputtering titanium plating in step (2) is 4.0×10 -3 -8.0×10 -3 Pa; Preferably, the sputtering voltage of the vacuum magnetron sputtering titanium plating is 80-120V; Preferably, the sputtering current of the vacuum magnetron sputtering titanium coating is 10-30 mA; Preferably, the sputtering time of the vacuum magnetron sputtering titanium coating is 3-5h; Preferably, the titanium coating thickness of the graphite target with titanium film is 2-5 μm; Preferably, the roughness of the titanium coating layer of the graphite target material with titanium film is 10-12 μm.

4. The brazing method according to any one of claims 1 to 3, characterized in that: Step (3) The material of the backplane includes any one of Al, Cu or Mo or a combination of at least two of them; Preferably, the target temperature of the heating is 200-220°C; Preferably, the heating rate of the heating is 2-5°C / min.

5. The brazing method according to any one of claims 1 to 4, characterized in that: The brazing in step (3) includes wetting, bonding, hot pressing and cooling in sequence.

6. The brazing method according to claim 5, characterized in that: The infiltration includes placing solder on the welding surface of the graphite target material with the titanium film and the welding surface of the back plate respectively and independently for infiltration; Preferably, the infiltration method includes ultrasonic infiltration; Preferably, the welding surface of the back plate is treated with a steel brush before the infiltration treatment; Preferably, the wetting time of the welding surface of the graphite target material with titanium film is 10-20 minutes; Preferably, the wetting time of the welding surface of the back plate is 10-15 minutes; Preferably, the material of the solder includes indium solder.

7. The brazing method according to claim 5 or 6, characterized in that: The lamination includes making a solder groove on the welding surface of the back plate, placing a copper wire in the solder groove, and then laminating the welding surface of the graphite target and the welding surface of the back plate; Preferably, the depth of the solder groove is 3-5 mm; Preferably, the length and width of the solder groove are the same as those of the back plate; Preferably, the diameter of the copper wire is 0.2-0.5 mm.

8. The brazing method according to any one of claims 5 to 7, characterized in that: The hot pressing comprises placing a buffer pad on the bonded graphite target material, and placing a pressing block on the buffer pad; Preferably, the temperature of the cushion is 200-220°C; Preferably, the buffer pad comprises a silicone pad or a wooden block; Preferably, the pressure of the briquetting is 0.3-0.5 MPa.

9. The brazing method according to any one of claims 5 to 8, characterized in that: The target temperature of the cooling is 25°C; Preferably, the cooling rate is 1-2°C / min.

10. The brazing method according to any one of claims 1 to 9, characterized in that: The brazing method comprises the following steps: (1) using white corundum to sandblast the welding surface of the graphite target, the pressure of the sandblasting is 0.3-0.4 MPa, and a graphite target with a roughness of 11-14 μm is obtained; (2) At 4.0×10 -3 -8.0×10 -3 The welding surface of the sandblasted graphite target is subjected to vacuum magnetron sputtering titanium coating at a vacuum degree of 1.5 Pa, and the thickness of the titanium coating layer is 2-5 μm, so as to obtain a graphite target with a titanium film having a roughness of 10-12 μm; (3) The back plate and the graphite target with titanium film are heated to the target temperature of 200-220°C at a heating rate of 2-5°C / min, respectively, and then molten solder is placed on the welding surface of the graphite target with titanium film, and the welding surface of the graphite target is infiltrated with an ultrasonic welding machine for 10-20 minutes; a manual steel brush and an ultrasonic welding machine are used to infiltrate the back plate for 10-15 minutes, and then a solder groove with a depth of 3-5mm is made on the welding surface of the back plate, and a copper wire with a diameter of 0.2-0.5mm is placed in the solder groove, and then the welding surface of the graphite target and the welding surface of the back plate are bonded, and a buffer pad is placed on the bonded graphite target, and a pressure block with a pressure of 0.3-0.5MPa is placed on the buffer pad. After the welding is completed, the welded graphite target and the back plate are cooled to 25°C at a cooling rate of 1-2°C / min, and then the pressure block is removed, and the brazing of the graphite target and the back plate is completed.

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