Welding method for high-quality diamond-based X-ray target

Abstract

The invention provides a welding method for a high-quality diamond-based X-ray target, which comprises the following steps of: screening out a welding material which does not influence the welding quality, and cleaning and drying a welding jig and the welding material; putting into a vacuum annealing furnace, and selecting a preset pretreatment curve for pretreatment; assembling the diamond, the preformed soldering lug and the target substrate from top to bottom according to different welding requirements of various materials; and after being assembled, the assembly is put into a vacuum reflow soldering furnace for vacuum reflow soldering. By optimizing process conditions, strictly controlling and screening soldering lugs, deeply cleaning related welding materials, then pretreating the soldering lugs, finally optimizing the welding process and strictly controlling temperature and time conditions, the voidage of diamond welding is reduced from original 24% to 5% and below or even reduced to 1%, and the welding quality is greatly improved. The problem of voidage of welding is greatly improved, and the heat dissipation efficiency of the diamond is greatly improved under the condition that the welding stability is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of X-ray tubes, and in particular to a welding method for high-quality diamond-based X-ray targets. Background Art

[0002] X-rays are often used for fluoroscopy in medicine and for flaw detection in industry; X-rays can be detected by ionization meters, scintillation counters, and photosensitive emulsions; X-ray diffraction has become an important means of studying crystal structure, morphology, and various defects, and is widely used. Diamond is widely used in the field of heat dissipation due to its efficient heat dissipation ability. When the target is bombarded by an electron beam, a large amount of heat will be generated on the target surface. If the heat cannot be dissipated in time, the target surface will be ablated or even melted, which will eventually lead to a serious decrease in the output quality of X-rays. However, because diamond welding has become a major problem, in order to give full play to the heat dissipation efficiency of diamond, good thermal conductivity must be ensured after welding. However, in the process of diamond welding, a huge void rate is often generated, which greatly affects the heat dissipation efficiency of diamond and cannot play the role of diamond. Summary of the invention

[0003] The present application is made in view of the above-mentioned problems, and its object is to provide a welding method for a high-quality diamond-based X-ray target with low void ratio and good heat dissipation effect.

[0004] In order to achieve the above object, the present application provides a welding method for a high-quality diamond-based X-ray target, comprising the following process steps:

[0005] 1) Screening and cleaning: Screen out welding materials without defects that affect welding quality in the welding area, and clean and dry the welding jigs and welding materials;

[0006] 2) Pretreatment: Put the cleaned welding materials into the material tray, and then put them into the vacuum annealing furnace, select the preset pretreatment curve, and then start the pretreatment before welding, the pretreatment is at a temperature of 150°C to 200°C;

[0007] 3) The pre-treated welding materials are assembled from top to bottom according to the three-layer structure of diamond, preformed solder sheet and target substrate using a jig according to the different welding requirements of various materials; after assembly, they are placed in a vacuum reflow oven for vacuum reflow soldering, and the diamond and target substrate are welded together by melting the solder sheet and causing a eutectic reaction.

[0008] In any embodiment, the screening process uses an electron microscope to screen the welding materials to ensure that there are no defects in the welding area that affect the welding quality; and the defective materials are directly excluded from the process, and the dirty materials are screened again after cleaning. The materials that have been cleaned in the secondary screening can enter the next process, and the dirty materials are excluded from the process.

[0009] In any embodiment, the defects include: ① pits and protrusions on the surface of the welded part that affect the wettability of the welding piece surface; ② welding coating defects such as holes, missing pieces, and dirt on the coating; ③ dirt, missing pieces, depressions, and impurities on the surface of the preformed welding piece.

[0010] In any embodiment, the cleaning process is to place the welding jig and the welding material on a cleaning rack in a beaker, respectively, and ultrasonically clean them using acetone, ultrapure water, and alcohol, respectively, with each cleaning solution ultrasonically cleaning for about ten minutes; after cleaning, use a nitrogen gun to blow dry the material in preparation for pretreatment.

[0011] In any embodiment, the cleaning process is to perform ultrasonic cleaning of acetone, alcohol and water in sequence for 10 minutes each, with an ultrasonic cleaning frequency of 28KHz-40KHz, wherein the acetone concentration is 13.5mol / L and the alcohol concentration is 97%.

[0012] In any embodiment, the pretreatment is performed in sequence by vacuum, high-purity nitrogen, and a mixed gas of high-purity nitrogen and formic acid.

[0013] In any embodiment, the pretreatment, when the sample is placed in a vacuum annealing furnace, it is evacuated and then filled with nitrogen for 3 to 5 cycles, and then nitrogen is continuously passed and heated in a nitrogen environment, heated to the pretreatment temperature and kept warm for 30 to 40 minutes. After the nitrogen atmosphere is kept warm, a mixed gas of high-purity nitrogen and formic acid is passed and kept warm for 5 to 10 minutes.

[0014] In any embodiment, in the pretreatment, the vacuum atmosphere condition is 5×10-2 mbar; the nitrogen purity is 99.999%, and the flow rate is 10 sccm; the formic acid concentration is 99%, the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10 sccm.

[0015] In any embodiment, the welding equipment used in the welding step is a vacuum eutectic furnace, and the eutectic furnace meets the following conditions: the dynamic vacuum degree can reach 2×10-3mbar, the temperature uniformity of the heated substrate is above 90%, the temperature control accuracy of the equipment is within ±0.5°C, the atmosphere in the furnace is controllable, the pressure in the furnace is controllable, and the atmosphere flow is controllable.

[0016] In any embodiment, the welding process uses a gold-tin solder preform, and the process curve is: first heat to a first-stage preheating temperature of 100°C to 170°C and keep warm for 10 to 20 minutes; then heat to a second preheating temperature of 250°C to 280°C and keep warm for 5 to 10 minutes; then heat to a peak temperature (welding temperature) of 310°C to 350°C for 50s to 70s, cool after completion, and take out the sample.

[0017] In any embodiment, high-purity nitrogen is passed 30 seconds before the peak temperature, and vacuum is started 30 seconds after the peak temperature; after the peak temperature is reached, high-purity nitrogen is used to quickly cool the temperature to 50°C.

[0018] In any embodiment, the surface of the target substrate is flat and free of pits and protrusions, and the surface roughness Ra is less than 400nm; the preformed solder sheet has no defects, surface impurities and no damage or creases; the diamond is required to be gold-plated on the surface, and the gold-plated film is titanium platinum gold, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold or titanium nickel gold, and the gold-plated layer is intact without scratches and the adhesion test is good.

[0019] Beneficial effects of the present invention: The present invention optimizes the process conditions, strictly controls the selection of welding pieces, deeply cleans the welding-related materials, pre-treats the welding pieces, and finally optimizes the welding process and strictly controls the temperature and time conditions, thereby reducing the void rate of diamond welding from the original 24% to 5% or less, or even to 1%, thereby greatly improving the void rate problem of welding and greatly improving the heat dissipation efficiency of diamond while ensuring welding stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a process flow chart of a welding method for a high-quality diamond-based X-ray target.

[0021] Figure 2 This is the CT image of the diamond-based X-ray target prepared in Comparative Example 1.

[0022] Figure 3 This is a CT image obtained in Example 4 of the present invention's method for welding a high-quality diamond-based X-ray target.

[0023] Figure 4 This is a CT void ratio diagram obtained in Example 5 of the welding method for a high-quality diamond-based X-ray target of the present invention. DETAILED DESCRIPTION

[0024] Hereinafter, the implementation method of the welding method of the high-quality diamond-based X-ray target of the present application is described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0025] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0027] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0028] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0029] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0030] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0031] A method for welding a high-quality diamond-based X-ray target comprises the following process steps:

[0032] 1) Screening and cleaning: Screen out welding materials without defects that affect welding quality in the welding area, and clean and dry the welding jigs and welding materials;

[0033] 2) Pretreatment: Put the cleaned welding materials into the material tray, and then put them into the vacuum annealing furnace, select the preset pretreatment curve, and then start the pretreatment before welding. The pretreatment is carried out at a temperature of 150℃ to 200℃;

[0034] 3) The pre-treated welding materials are assembled from top to bottom according to the three-layer structure of diamond, preformed solder sheet and target substrate using a jig according to the different welding requirements of various materials; after assembly, they are placed in a vacuum reflow oven for vacuum reflow soldering, and the diamond and target substrate are welded together by melting the solder sheet and causing a eutectic reaction.

[0035] The jig refers to the jig used for welding limit, and the welding materials refer to the preformed solder sheet, the gold-plated diamond, and the target substrate onto which the diamond needs to be welded.

[0036] The present application firstly passes through a screening step, which can eliminate some of the problems that affect the void rate, so that materials with surface defects and impurities do not flow into the welding process; then, through pretreatment, water vapor and various impurity oxides in the welding piece are removed in advance, and the surface wettability of the welding piece and the weldment is increased; finally, the vacuuming process and temperature details are optimized to achieve the low welding void rate of the present application, while ensuring welding stability and improving the heat dissipation efficiency of diamond.

[0037] In some embodiments, the screening process uses an electron microscope to screen the welding materials to ensure that there are no defects in the welding area that affect the welding quality; and the defective materials are directly excluded from the process, and the dirty materials are screened again after cleaning. The materials that have been cleaned from the dirt in the secondary screening can enter the next process, and the dirty materials are excluded from the process.

[0038] In some embodiments, the defects include: ① defects such as pits and protrusions on the surface of the welded part that affect the wettability of the surface of the welding piece; ② defects such as holes, missing pieces, and dirty coatings on the welding coating; ③ dirt, missing pieces, depressions, and impurities on the surface of the preformed welding piece.

[0039] In some embodiments, the cleaning process is to place the welding jig, welding sheet, and welding parts on a cleaning rack in a beaker, respectively, and use acetone, ultrapure water, and alcohol for ultrasonic cleaning, respectively, and each cleaning solution is ultrasonically cleaned for about ten minutes; after cleaning, use a nitrogen gun to blow dry the material in preparation for pretreatment.

[0040] Purpose: To remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface.

[0041] In some embodiments, the cleaning process includes ultrasonic cleaning of acetone, alcohol, and water in sequence for 10 minutes each, with an ultrasonic cleaning frequency of 28KHz-40KHz, wherein the acetone concentration is 13.5mol / L, and the alcohol concentration is 97%.

[0042] There is no ratio between cleaning fluids, only a sequence.

[0043] In some embodiments, the pretreatment is performed in sequence by vacuum, high-purity nitrogen, and a mixed gas of high-purity nitrogen and formic acid.

[0044] In some embodiments, for the pretreatment, when the sample is placed in a vacuum annealing furnace, it is evacuated and then filled with nitrogen for 3 to 5 cycles, and then nitrogen is continuously passed and heated in a nitrogen environment, heated to the pretreatment temperature and kept warm for 30 to 40 minutes. After the nitrogen atmosphere is kept warm, a mixed gas of high-purity nitrogen and formic acid is passed and kept warm for 5 to 10 minutes.

[0045] Vacuum annealing furnace: The main feature of this furnace is that it can accurately control temperature, evacuate, increase the required furnace atmosphere, etc. Other equipment that meets the above conditions can also be used as pretreatment equipment.

[0046] The purpose of vacuuming and then filling with nitrogen is to remove oxygen, moisture, etc.

[0047] In some embodiments, during the pretreatment, the vacuum atmosphere condition is 5×10-2 mbar; the nitrogen purity is 99.999%, and the flow rate is 10 sccm; the formic acid concentration is 99%, and the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10 sccm.

[0048] In some embodiments, the welding equipment used in the welding step is a vacuum eutectic furnace, and the eutectic furnace meets the following conditions: the dynamic vacuum degree can reach 2×10-3mbar, the temperature uniformity of the heated substrate is above 90%, the temperature control accuracy of the equipment is within ±0.5°C, the atmosphere in the furnace is controllable, the pressure in the furnace is controllable, and the atmosphere flow is controllable.

[0049] In some embodiments, the welding process uses a gold-tin solder preform, and the process curve is as follows: first heat to a first preheating temperature of 100°C to 170°C and keep warm for 10 to 20 minutes; then heat to a second preheating temperature of 250°C to 280°C and keep warm for 5 to 10 minutes; then heat to a peak temperature (welding temperature) of 310°C to 350°C for 50s-70s, cool after completion, and take out the sample.

[0050] In some embodiments, high-purity nitrogen is passed 30 seconds before the peak temperature, and vacuum is started 30 seconds after the peak temperature; after the peak temperature is reached, high-purity nitrogen is used to quickly cool the temperature to 50°C.

[0051] In some embodiments, the surface of the target substrate is flat and free of pits and protrusions, and the surface roughness Ra is less than 400nm; the preformed solder sheet has no defects, surface impurities and no damage or creases; the diamond requires surface gold plating, and the gold plating film is titanium platinum gold, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold or titanium nickel gold, and the gold plating layer is intact without scratches and the adhesion test is good.

[0052] Example

[0053] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0054] Example 1

[0055] A method for welding a high-quality diamond-based X-ray target comprises the following process steps:

[0056] 1) The first process is screening. Using an electron microscope, the welding materials are screened to ensure that defective materials are directly excluded from the process. Dirty materials are screened again after cleaning. The materials that have been cleaned in the second screening can enter the next process, and the dirty materials are excluded from the process. The main defects are: ① Defects such as pits and protrusions on the surface of the welded parts that affect the wettability of the soldering sheet surface; ② Plating defects, such as holes, missing pieces, and dirt in the welding plating; ③ Dirt, missing pieces, depressions, impurities, etc. on the surface of the preformed solder sheet.

[0057] 2) The second step is cleaning. The welding jig, welding sheet and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed with acetone, ultrapure water and alcohol respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5 mol / L, the alcohol concentration is 97%, and the acetone, alcohol and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 28KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, the material is blown dry with a nitrogen gun to prepare for pretreatment.

[0058] 3) The third step is pretreatment, which is mainly carried out in a vacuum annealing furnace. The cleaned material is placed in a material tray and then placed in a vacuum annealing furnace. A preset pretreatment curve is selected and then the pretreatment before welding is started. The pretreatment function is mainly to remove water vapor, impurities, oxide layer, etc. on the surface of the material through certain vacuum, atmosphere, temperature and other conditions; the pretreatment process limits the treatment temperature to 150°C, and the atmosphere conditions are vacuum, high-purity nitrogen, and a mixture of high-purity nitrogen and formic acid in sequence. Vacuuming and then filling with nitrogen for 3 cycles are performed to remove internal oxygen and moisture, and then nitrogen is continuously passed and heated in a nitrogen environment. When heated to the pretreatment temperature, it is kept warm for 30 minutes. After the nitrogen atmosphere is kept warm, a mixture of high-purity nitrogen and formic acid is passed, and then kept warm for 5 minutes; wherein the vacuum atmosphere condition is 5×10 - 2 mbar; nitrogen purity is 99.999%, flow rate is 10sccm; formic acid concentration is 99%, the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10sccm.

[0059] 4) After that, the pre-treated welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure of diamond, preformed solder sheet, and target substrate from top to bottom. The preformed solder sheet used is a gold-tin solder sheet, which can be an Au80Sn20 preformed solder sheet. The target substrate requires a flat surface without pits and protrusions, and a surface roughness Ra <400nm; the preformed solder sheet is free of defects, surface impurities, and no damage or creases; the diamond requires a gold-plated surface, and the gold-plated film can be titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold-plated layer is required to be intact without scratches and good adhesion test; the diamond and the target substrate are welded together by melting the solder sheet and generating a eutectic reaction; after assembly, they are placed in a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 150°C, and then keep warm for 20 minutes in the first preheating stage. Then the temperature is raised to the second preheating temperature, which is approximately 280°C, and then kept warm for 10 minutes in the second preheating stage. Then the temperature is raised to the peak temperature (welding temperature), which is 310°C, and the peak temperature lasts for 1 minute, with high-purity nitrogen passing for the first 30 seconds and vacuuming for the last 30 seconds. After the end, high-purity nitrogen is used to quickly cool to 50°C, and the sample can be taken out.

[0060] The porosity of the diamond-based X-ray target was measured and the result was about 4.8%.

[0061] Example 2

[0062] A method for welding a high-quality diamond-based X-ray target comprises the following process steps:

[0063] 1) The first process is screening. Using an electron microscope, the welding materials are screened to ensure that defective materials are directly excluded from the process. Dirty materials are screened again after cleaning. The materials that have been cleaned in the second screening can enter the next process, and the dirty materials are excluded from the process. The main defects are: ① Defects such as pits and protrusions on the surface of the welded parts that affect the wettability of the soldering sheet surface; ② Plating defects, such as holes, missing pieces, and dirt in the welding plating; ③ Dirt, missing pieces, depressions, impurities, etc. on the surface of the preformed solder sheet.

[0064] 2) The second step is cleaning. The welding jig, welding sheet and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed with acetone, ultrapure water and alcohol respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5 mol / L, the alcohol concentration is 97%, and the acetone, alcohol and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 30KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, the material is blown dry with a nitrogen gun to prepare for pretreatment.

[0065] 3) The third step is pretreatment, which is mainly carried out in a vacuum annealing furnace. The cleaned material is placed in a material tray and then placed in a vacuum annealing furnace. A preset pretreatment curve is selected and then the pretreatment before welding is started. The pretreatment function is mainly to remove water vapor, impurities, oxide layer, etc. on the surface of the material through certain vacuum, atmosphere, temperature and other conditions; the pretreatment process limits the treatment temperature to 180°C, and the atmosphere conditions are vacuum, high-purity nitrogen, and a mixture of high-purity nitrogen and formic acid in sequence. Vacuuming and then filling with nitrogen for 4 cycles are carried out to remove internal oxygen and moisture, and then nitrogen is continuously passed and heated in a nitrogen environment. When heated to the pretreatment temperature, it is kept warm for 35 minutes. After the nitrogen atmosphere is kept warm, a mixture of high-purity nitrogen and formic acid is passed, and then kept warm for 8 minutes; wherein the vacuum atmosphere condition is 5×10 -2 mbar; nitrogen purity is 99.999%, flow rate is 10sccm; formic acid concentration is 99%, the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10sccm.

[0066] 4) After that, the pre-treated welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure from top to bottom, which is diamond, preformed solder sheet, and target substrate. The preformed solder sheet used is a gold-tin solder sheet. The target substrate requires a flat surface without pits and protrusions, and a surface roughness Ra <400nm; the preformed solder sheet is free of defects, surface impurities, and no damage or creases; the diamond requires a gold-plated surface, and the gold-plated film can be selected from titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold-plated layer is required to be intact without scratches and good adhesion test; the diamond and the target substrate are welded together by melting the solder sheet and causing eutectic reaction; after assembly, they are placed in a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 150°C, and then keep warm for 15 minutes in the first preheating stage. Then the temperature is raised to the second preheating temperature, which is approximately 280°C, and then kept at this temperature for 7 minutes in the second preheating stage. Then the temperature is raised to the peak temperature (welding temperature), which is 330°C, and the peak temperature lasts for 1 minute, with high-purity nitrogen passing for the first 30 seconds and vacuuming for the last 30 seconds. After the end, high-purity nitrogen is used to quickly cool to 50°C, and the sample can be taken out.

[0067] The porosity of the diamond-based X-ray target was measured and found to be approximately 3%.

[0068] Example 3

[0069] A method for welding a high-quality diamond-based X-ray target comprises the following process steps:

[0070] 1) The first process is screening. Using an electron microscope, the welding materials are screened to ensure that defective materials are directly excluded from the process. Dirty materials are screened again after cleaning. The materials that have been cleaned in the second screening can enter the next process, and the dirty materials are excluded from the process. The main defects are: ① Defects such as pits and protrusions on the surface of the welded parts that affect the wettability of the soldering sheet surface; ② Plating defects, such as holes, missing pieces, and dirt in the welding plating; ③ Dirt, missing pieces, depressions, impurities, etc. on the surface of the preformed solder sheet.

[0071] 2) The second step is cleaning. The welding jig, welding sheet and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed with acetone, ultrapure water and alcohol respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5 mol / L, the alcohol concentration is 97%, and the acetone, alcohol and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 40KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, the material is blown dry with a nitrogen gun to prepare for pretreatment.

[0072] 3) The third step is pretreatment, which is mainly carried out in a vacuum annealing furnace. The cleaned material is placed in a material tray and then placed in a vacuum annealing furnace. A preset pretreatment curve is selected and then the pretreatment before welding is started. The pretreatment function is mainly to remove water vapor, impurities, oxide layer, etc. on the surface of the material through certain vacuum, atmosphere, temperature and other conditions; the pretreatment process limits the treatment temperature to 200°C, and the atmosphere conditions are vacuum, high-purity nitrogen, and a mixture of high-purity nitrogen and formic acid in sequence. The vacuum is evacuated and then filled with nitrogen for 5 cycles to remove internal oxygen and moisture, and then nitrogen is continuously passed and heated in a nitrogen environment. When heated to the pretreatment temperature, it is kept warm for 10 minutes. After the nitrogen atmosphere is kept warm, a mixture of high-purity nitrogen and formic acid is passed, and then kept warm for 10 minutes; wherein the vacuum atmosphere condition is 5×10 -2 mbar; nitrogen purity is 99.999%, flow rate is 10sccm; formic acid concentration is 99%, the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10sccm.

[0073] 4) After that, the pre-treated welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure from top to bottom, which is diamond, preformed solder sheet, and target substrate. The preformed solder sheet used is a gold-tin solder sheet. The target substrate requires a flat surface without pits and protrusions, and a surface roughness Ra <400nm; the preformed solder sheet is free of defects, surface impurities, and no damage or creases; the diamond requires a gold-plated surface, and the gold-plated film can be selected from titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold-plated layer is required to be intact without scratches and good adhesion test; the diamond and the target substrate are welded together by melting the solder sheet and causing eutectic reaction; after assembly, they are placed in a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 170°C, and then keep warm for 10 minutes in the first preheating stage. Then the temperature is raised to the second preheating temperature, which is approximately 280°C, and then kept at this temperature for 5 minutes in the second preheating stage. Then the temperature is raised to the peak temperature (welding temperature), which is 350°C, and the peak temperature lasts for 1 minute, with high-purity nitrogen passing for the first 30 seconds and vacuuming for the last 30 seconds. After the end, high-purity nitrogen is used to quickly cool to 50°C, and the sample can be taken out.

[0074] The porosity of the diamond-based X-ray target was measured and found to be approximately 1.5%.

[0075] Comparative Example 1

[0076] A method for welding a diamond-based X-ray target comprises the following process steps:

[0077] 1) The first step is cleaning. The welding jig, welding sheet, and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed using acetone, ultrapure water, and alcohol, respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5 mol / L, the alcohol concentration is 97%, and the acetone, alcohol, and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 40KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, use a nitrogen gun to blow dry the material and prepare for welding.

[0078] 2) After that, the cleaned welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure of diamond, preformed solder sheet, and target substrate from top to bottom. The preformed solder sheet used is a gold-tin solder sheet. The diamond requires gold plating on the surface. The gold-plated film can be titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold plating layer is required to be intact without scratches and have good adhesion test; after assembly, put it into a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 150°C, and then keep warm for 2 minutes in the first preheating stage. Then heat up to the second preheating temperature, which is approximately 250°C, and then keep warm for 2 minutes in the second preheating stage. Then heat up to the peak temperature (welding temperature), the temperature is 350°C, the peak temperature lasts for 2 minutes, and high-purity nitrogen is passed during the welding process. After the end, use high-purity nitrogen to quickly cool to 50°C, and the sample can be taken out.

[0079] The porosity of the diamond-based X-ray target was measured and found to be approximately 15%.

[0080] Comparative Example 2

[0081] A method for welding a diamond-based X-ray target comprises the following process steps:

[0082] 1) The first step is cleaning. The welding jig, welding sheet, and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed using acetone, ultrapure water, and alcohol, respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5 mol / L, the alcohol concentration is 97%, and the acetone, alcohol, and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 40KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, use a nitrogen gun to blow dry the material and prepare for welding.

[0083] 2) After that, the cleaned welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure from top to bottom, which is diamond, preformed solder sheet, and target substrate. The preformed solder sheet used is a gold-tin solder sheet. The diamond requires gold plating on the surface. The gold-plated film can be titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold plating layer is required to be intact without scratches and good adhesion test; after assembly, put it into a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 250°C, and then keep warm for 2 minutes in the first preheating stage. Then heat up to the peak temperature (welding temperature), the temperature is 310°C, the peak temperature lasts for 2 minutes, and high-purity nitrogen is passed during the welding process. After the end, use high-purity nitrogen to quickly cool to 50°C, and the sample can be taken out.

[0084] The porosity of the diamond-based X-ray target was measured and found to be approximately 25%.

[0085] Comparative Example 3

[0086] A method for welding a diamond-based X-ray target comprises the following process steps:

[0087] 1) The first process is screening. Using an electron microscope, the welding materials are screened to ensure that defective materials are directly excluded from the process. Dirty materials are screened again after cleaning. The materials that have been cleaned in the second screening can enter the next process, and the dirty materials are excluded from the process. The main defects are: ① Defects such as pits and protrusions on the surface of the welded parts that affect the wettability of the soldering sheet surface; ② Plating defects, such as holes, missing pieces, and dirt in the welding plating; ③ Dirt, missing pieces, depressions, impurities, etc. on the surface of the preformed solder sheet.

[0088] 2) The first step is cleaning. The welding jig, welding sheet and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed with acetone, ultrapure water and alcohol respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5mol / L, the alcohol concentration is 97%, and the acetone, alcohol and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 40KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, use a nitrogen gun to blow dry the material and prepare for welding.

[0089] 3) After that, the cleaned welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure of diamond, preformed solder sheet, and target substrate from top to bottom. The preformed solder sheet used is a gold-tin solder sheet. The diamond requires gold plating on the surface. The gold-plated film can be titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold plating layer is required to be intact without scratches and have good adhesion test; after assembly, put it into a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 150°C, and then keep warm for 2 minutes in the first preheating stage. Then heat up to the second preheating temperature, which is approximately 250°C, and then keep warm for 2 minutes in the second preheating stage. Then heat up to the peak temperature (welding temperature), the temperature is 350°C, the peak temperature lasts for 2 minutes, and high-purity nitrogen is passed during the welding process. After the end, use high-purity nitrogen to quickly cool to 50°C, and the sample can be taken out.

[0090] The porosity of the diamond-based X-ray target was measured and found to be approximately 10%.

[0091] Comparative Example 4

[0092] A method for welding a diamond-based X-ray target comprises the following process steps:

[0093] 1) The first step is cleaning. The welding jig, welding sheet, and welding parts are placed on the cleaning rack in the beaker, and ultrasonic cleaning is performed using acetone, ultrapure water, and alcohol, respectively. Each cleaning solution is ultrasonically cleaned for ten minutes. In the cleaning process, the acetone concentration is 13.5 mol / L, the alcohol concentration is 97%, and the acetone, alcohol, and water are ultrasonically cleaned for 10 minutes in sequence. The ultrasonic cleaning frequency is 40KHz; the purpose is to remove organic matter, inorganic salts, water-soluble impurities, etc. on the surface. After cleaning, use a nitrogen gun to blow dry the material and prepare for welding.

[0094] 2) Pretreatment, the treatment temperature is limited to 200 ° C, the atmosphere conditions are vacuum, high-purity nitrogen, high-purity nitrogen and formic acid mixed gas, vacuum and then nitrogen filling for 5 cycles, the purpose is to remove internal oxygen and moisture, and then continue to pass nitrogen and heat in a nitrogen environment. When heated to the pretreatment temperature, keep warm for 10 minutes. After the nitrogen atmosphere is kept warm, pass high-purity nitrogen and formic acid mixed gas, and then keep warm for 10 minutes; the vacuum atmosphere condition is 5×10 -2 mbar; nitrogen purity is 99.999%, flow rate is 10sccm; formic acid concentration is 99%, the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10sccm.

[0095] 3) After that, the cleaned welding parts are assembled according to the different welding requirements of various materials. The assembly is a three-layer structure from top to bottom, which is diamond, preformed solder sheet, and target substrate. The preformed solder sheet used is a gold-tin solder sheet. The diamond requires gold plating on the surface. The gold-plated film can be titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold, titanium nickel gold and other film layers. The gold plating layer is required to be intact without scratches and good adhesion test; after assembly, put it into a vacuum reflow oven for vacuum reflow soldering; the welding equipment used is a vacuum eutectic furnace, and the welding process curve is: first heat up to the first stage preheating temperature, which is approximately 250°C, and then keep warm for 2 minutes in the first preheating stage. Then heat up to the peak temperature (welding temperature), the temperature is 350°C, the peak temperature lasts for 2 minutes, and high-purity nitrogen is passed during the welding process. After the end, use high-purity nitrogen to quickly cool to 50°C, and the sample can be taken out.

[0096] The porosity of the diamond-based X-ray target was measured and found to be approximately 12%.

[0097] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for welding a high-quality diamond-based X-ray target, characterized in that: The process steps include: 1) Screening and cleaning: Screen out welding materials without defects that affect welding quality in the welding area, and clean and dry the welding jigs and welding materials; 2) Pretreatment: Put the cleaned welding materials into the material tray, and then put them into the vacuum annealing furnace, select the preset pretreatment curve, and then start the pretreatment before welding, the pretreatment is at a temperature of 150°C to 200°C; 3) The pre-treated welding materials are assembled from top to bottom according to the three-layer structure of diamond, preformed solder sheet and target substrate using a jig according to the different welding requirements of various materials; after assembly, they are placed in a vacuum reflow oven for vacuum reflow soldering, and the diamond and target substrate are welded together by melting the solder sheet and causing a eutectic reaction.

2. The welding method of a high-quality diamond-based X-ray target according to claim 1, characterized in that: The screening process uses an electron microscope to screen the welding materials to ensure that there are no defects that affect the welding quality in the welding area; and the defective materials are directly excluded from the process. The dirty materials are cleaned and then screened again. The materials that have been cleaned in the secondary screening can enter the next process, and the dirty materials are excluded from the process.

3. A method for welding a high-quality diamond-based X-ray target according to claim 1 or 2, characterized in that: The cleaning process is to place the welding jig, welding sheet and welding parts on the cleaning rack in the beaker respectively, and use acetone, ultrapure water and alcohol for ultrasonic cleaning respectively, and each cleaning solution is ultrasonically cleaned for about ten minutes; after cleaning, use a nitrogen gun to blow dry the material in preparation for pretreatment.

4. The welding method of a high-quality diamond-based X-ray target according to claim 3, characterized in that: The cleaning process includes performing ultrasonic cleaning of acetone, alcohol and water in sequence for 10 minutes each, with an ultrasonic cleaning frequency of 28KHz-40KHz, wherein the acetone concentration is 13.5mol / L and the alcohol concentration is 97%.

5. The welding method of a high-quality diamond-based X-ray target according to claim 1, characterized in that: The pretreatment is performed in sequence using vacuum, high-purity nitrogen, and a mixed gas of high-purity nitrogen and formic acid.

6. A method for welding a high-quality diamond-based X-ray target according to claim 1 or 5, characterized in that: For the pretreatment, when the sample is placed in a vacuum annealing furnace, it is evacuated and then filled with nitrogen for 3 to 5 cycles, and then nitrogen is continuously passed and heated in a nitrogen environment, heated to the pretreatment temperature and kept warm for 30 to 40 minutes. After the nitrogen atmosphere is kept warm, a mixed gas of high-purity nitrogen and formic acid is passed and kept warm for 5 to 10 minutes.

7. A method for welding a high-quality diamond-based X-ray target according to claim 6, characterized in that: In the pretreatment, the vacuum atmosphere condition is 5×10-2 mbar; the purity of nitrogen is 99.999%, and the flow rate is 10 sccm; the concentration of formic acid is 99%, and the mixing ratio with high-purity nitrogen is 1:1, and the flow rate is 10 sccm.

8. The welding method of a high-quality diamond-based X-ray target according to claim 1, characterized in that: The welding process uses a gold-tin solder preform, and the process curve is as follows: firstly, the temperature is raised to a first-stage preheating temperature of 100°C to 170°C and kept warm for 10 to 20 minutes; then, the temperature is raised to a second preheating temperature of 250°C to 280°C and kept warm for 5 to 10 minutes; then, the temperature is raised to a peak temperature (welding temperature) of 310°C to 350°C for 50s to 70s, and then, the temperature is cooled and the sample is taken out.

9. The welding method of a high-quality diamond-based X-ray target according to claim 1, characterized in that: High-purity nitrogen was passed for 30 seconds before the peak temperature, and vacuum was started for 30 seconds after the peak temperature; high-purity nitrogen was used to quickly cool the temperature to 50° C. after the peak temperature.

10. The welding method of a high-quality diamond-based X-ray target according to claim 1, characterized in that: The surface of the target substrate is flat and free of pits and protrusions, and the surface roughness Ra is less than 400nm; the preformed solder sheet has no defects, surface impurities, and no damage or creases; the diamond is required to be gold-plated on the surface, and the gold-plated film is titanium platinum, titanium tungsten gold, titanium molybdenum gold, chromium nickel gold, chromium palladium gold or titanium nickel gold. The gold-plated layer is intact and has no scratches and good adhesion test.

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