Method for improving heat exchange coefficient of water-cooled plate interface and water-cooled plate

Abstract

This invention discloses a method for improving the interfacial heat transfer coefficient of a water-cooled plate and the water-cooled plate itself. The method includes the following steps: S1: machining a flow channel groove on the aluminum base of the cooling plate; S2: setting a solder layer at the bottom of the flow channel groove; S3: bending a stainless steel cooling water pipe along the path of the flow channel groove and embedding the stainless steel cooling water pipe into the flow channel groove along the path of the flow channel groove; S4: deforming the stainless steel cooling water pipe through a cold pressing process and then tightly fitting it inside the flow channel groove; S5: setting a second solder layer on the stainless steel cooling water pipe, then setting a first solder layer on the brazing surface of the water-cooled plate, and finally, covering the cooling plate with a cover plate to complete the pre-assembly of the water-cooled plate; S6: welding the pre-assembled water-cooled plate using a vacuum brazing process to complete the fabrication of the aluminum alloy water-cooled plate. This method effectively improves the heat transfer efficiency between the stainless steel cooling water pipe and the water-cooled plate, ensuring the temperature stability and consistency of the water-cooled plate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment technology, specifically to a method for improving the interface heat transfer coefficient of a water-cooled plate, and particularly to a method for improving the interface heat transfer coefficient of an aluminum alloy water-cooled plate after vacuum brazing of embedded stainless steel cooling water pipes. Background Technology

[0002] In semiconductor equipment manufacturing, water-cooled plates (usually referring to water-cooled substrates or cooling plates integrated inside equipment) play a crucial role in temperature control and heat pipe function (such as the reaction chambers of etching machines, PECVD, and other equipment). Water-cooled plates are not only conventional heat dissipation components, but also core condition control units that determine whether the process can be carried out accurately.

[0003] Aluminum alloys (especially 6061 aluminum alloy) have become the mainstream material for semiconductor equipment manufacturing due to their excellent thermal conductivity, machinability, weldability, corrosion resistance, and outstanding anodizing properties. To precisely control the process temperature and the uniformity and stability of the production process, conventional water-cooled pans typically integrate complex circulating cooling channels. This process usually involves CNC (computer-controlled machine tool) precision machining of the cooling channels on the water-cooled pan body, followed by vacuum brazing to weld the cover plate to the body as a single unit. Embedding stainless steel cooling water pipes into aluminum alloy water-cooled pans is a technological upgrade based on considerations of reliability, corrosion resistance, and cleanliness. This is because stainless steel offers superior corrosion resistance, pressure resistance, and sealing safety. Replacing the pure aluminum alloy body with directly flowing water (i.e., machining channels directly on the aluminum alloy and flowing coolant) with brazed embedded stainless steel cooling water pipes represents a significant improvement.

[0004] However, in actual production, the following problems were found in the welding of the embedded cooling water pipes in the water-cooling plate: Because the dimensions of the stainless steel cooling water pipe bends deviate from the theoretical dimensions, especially when the bending angle is too large, the pipe wall surface undergoes tensile / compression deformation, resulting in local unevenness on the pipe wall surface. This prevents it from tightly fitting with the stainless steel grooves machined on the main body of the water cooling plate, thus affecting the temperature stability and consistency of the water cooling plate.

[0005] Due to the differences in the size, shape, and welding conditions of the welding wire filling both sides of the stainless steel cooling water pipe, the welding wire cannot fully melt under the same brazing temperature process parameters, thus failing to fully fill the assembly gap between the stainless steel cooling water pipe and the water cooling plate, reducing the heat transfer efficiency between the stainless steel cooling water pipe and the water cooling plate.

[0006] To improve the cooling effect of cooling plates, for example, Chinese patent document CN 115627464A discloses a novel cooling plate and its manufacturing process. Chemical nickel plating of the cooling pipes can isolate the water-cooling plate base from contact with the copper pipes, preventing copper and aluminum from adhering and forming high-melting-point oxides, which would make it difficult for the weld metal to fully fuse. However, this process has problems such as complex manufacturing and high cost. Summary of the Invention

[0007] This invention aims to solve the problem in the existing process of brazing stainless steel cooling water pipes into aluminum alloy water cooling pans. Due to the inability to quantify the amount of filler wire and the incomplete melting of the filler wire, welding gaps exist between the stainless steel cooling water pipes and the aluminum alloy chuck, resulting in poor fit and low heat exchange efficiency. Consequently, this leads to poor temperature uniformity and consistency in the product. The invention provides a method and a water cooling pan that improves the interfacial heat transfer coefficient of the water cooling pan. This method is convenient to operate, low in cost, and effectively improves the heat transfer efficiency between the stainless steel cooling water pipes and the water cooling pan, ensuring the temperature stability and consistency of the water cooling pan.

[0008] The technical solution adopted by this invention to achieve its first inventive objective is: a method for improving the interfacial heat transfer coefficient of a water-cooled plate, comprising the following steps: S1: The flow channel groove machined on the aluminum base of the cooling plate; S2: A solder layer is set at the bottom of the flow channel slot; S3: Bend the stainless steel cooling water pipe to match the path of the flow channel groove; and embed the stainless steel cooling water pipe into the flow channel groove along the path of the flow channel groove. S4: The stainless steel cooling water pipe is squeezed and deformed by cold pressing process and then tightly fitted into the inside of the flow channel groove. S5: Place solder 2 on the stainless steel cooling water pipe, then place solder 1 on the brazing surface of the water cooling plate, and finally cover the cooling plate to complete the pre-assembly of the water cooling plate. S6: The pre-assembled water cooling plate is welded using a vacuum brazing process to complete the fabrication of the aluminum alloy water cooling plate.

[0009] This method for improving the interfacial heat transfer coefficient of a water-cooled plate involves using a cold-pressing process to allow the stainless steel cooling water pipes to undergo plastic deformation, resulting in a better fit against the inner wall of the flow channel groove of the water-cooled plate. Welding material is added to the bottom and surface of the cooling water pipes, and after vacuum brazing, the melted welding material fully fills the gap between the outer wall of the cooling water pipe and the inner wall of the flow channel groove, effectively improving the interfacial heat transfer coefficient of the stainless steel water pipes embedded in the aluminum alloy water-cooled plate after vacuum brazing.

[0010] Preferably, the width and depth of the groove cross-section in step 1 are not equal.

[0011] Preferably, in step 2, the solder layer is a foil-shaped brazing filler metal or brazing paste with a thickness of 0.1 mm; the solder layer is made by laser cutting to conform the flow channel shape, or the solder layer is coated. During the assembly process before vacuum brazing, a 0.1 mm thick flow channel conforming brazing filler metal is spread inside the flow channel groove below the cooling water pipe. The brazing filler metal, after being melted at high temperature during vacuum brazing, can fill the gap between the bottom of the groove and the cooling water pipe, thereby achieving the wrapping of the lower pipe wall after extrusion and increasing the interfacial heat transfer coefficient.

[0012] Preferably, in step 3, the stainless steel cooling water pipe needs to be annealed after bending. Annealing after bending eliminates internal stress and prevents cracking.

[0013] Preferably, in step 4, the stainless steel cooling water pipe is cold-pressed using a cold press. After cold pressing, the surface of the cooling water pipe is 0.10~0.20mm lower than the brazing surface of the water cooling plate. The cold press precisely applies pressure to the cooling water pipe at the flow channel. The strong press pressure causes the cooling water pipe to be embedded in the flow channel groove of the water cooling plate and to undergo elastic deformation, better conforming to the inner wall of the flow channel groove. Since the surface of the cold-pressed cooling water pipe is lower than the brazing surface of the water cooling plate, it facilitates the filling and wrapping of the entire outer wall of the pipe with solder, thereby effectively improving the interfacial heat transfer coefficient after welding.

[0014] Preferably, in step 4, a special cold pressing fixture is used for cold pressing. The special cold pressing fixture includes an integrally formed cold pressing plate body, on which a flow channel contouring boss is provided. The height of the flow channel contouring boss is 0.25~0.35mm.

[0015] Preferably, in step 5, solder two is set as a flow channel conformal solder with a thickness of 0.1 mm; solder one is set as a solder with a thickness of 0.1 mm and the same shape as the brazing surface of the water cooling plate. The double-layer solder at the flow channel can better fill the gap between the cold-pressed water pipe and the brazing surface.

[0016] Preferably, the solder layer, solder two, and solder one are made of the same material, namely 4104 brazing filler metal or 4004 brazing filler metal. Using 0.1mm thick 4104 or 4004 brazing filler metal, with identical welding conditions and the same brazing process temperature, the filler metal melts sufficiently, resulting in good filling of the gaps on both sides of the cooling water pipe, eliminating the need for additional adjustment of the brazing process temperature.

[0017] Preferably, the cooling plate cover in step 5 is an integral cover with water pipe through holes and consistent with the base; or the cooling plate cover is a flow channel conformal cover.

[0018] The technical solution adopted by this invention to achieve its second objective is: a water-cooled plate manufactured using the aforementioned method for improving the interfacial heat transfer coefficient of a water-cooled plate. The aluminum alloy water-cooled plate includes an aluminum base body, stainless steel cooling water pipes, and a cooling plate cover. The aluminum base body has a brazing surface for the water-cooled plate, and flow channel grooves are formed on the brazing surface. The stainless steel cooling water pipes are embedded in the flow channel grooves in an extruded and deformed structure, and the outer wall of the cooling water pipes is coated with a solder layer. This water-cooled plate is easy to operate, low in cost, and can effectively improve the heat transfer efficiency between the stainless steel cooling water pipes and the water-cooled plate, ensuring the temperature stability and consistency of the water-cooled plate.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. The bent cooling water pipe is cold-pressed by a cold pressing fixture. The cold pressing fixture applies pressure precisely to the cooling water pipe at the flow channel groove. The strong press pressure makes the cooling water pipe embedded in the flow channel groove of the water cooling plate and causes the cooling water pipe to undergo elastic deformation, which better fits the inner wall of the flow channel groove. The stainless steel cooling water pipe has a high degree of fit with the flow channel groove of the water cooling plate, which can improve the temperature stability and consistency of the cold water plate.

[0020] 2. Solder is added to the bottom and surface of the cooling water pipes, using the same specifications of solder. The welding conditions are identical, and the solder melts fully under the same brazing process temperature. This results in good filling of the gaps between the cooling water pipes on both sides, eliminating the need for additional adjustments to the brazing process temperature. After vacuum brazing, the melted solder effectively fills the gap between the outer wall of the cooling water pipe and the inner wall of the flow channel groove, significantly improving the interfacial heat transfer coefficient of the stainless steel water pipes embedded in the aluminum alloy water cooling plate after vacuum brazing. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an aluminum alloy water cooling plate in this invention.

[0022] Figure 2 This is an exploded structural diagram of the aluminum alloy water cooling plate manufacturing process in this invention.

[0023] Figure 3 This is a schematic diagram of a combined structure in the manufacturing process of the aluminum alloy water cooling plate of the present invention.

[0024] Figure 4 This is a schematic diagram of the cooling water pipe cold pressing process in this invention.

[0025] Figure 5 This is a cross-sectional view of the cooling water pipe cold pressing process in this invention.

[0026] Figure 6 This is a schematic diagram of one structure for laying brazing filler metal in this invention.

[0027] Figure 7 This is a cross-sectional view of the aluminum alloy water cooling plate before brazing after assembly in this invention.

[0028] Figure 8 This is a schematic diagram of a special cold pressing fixture in this invention.

[0029] In the picture: 1. Aluminum alloy water cooling plate; 2. Aluminum-based cooling plate body; 21. Flow channel groove; 22. Brazing surface of water cooling plate; 3. Cooling water pipes; 4. Cooling plate cover; 5. Brazing filler metal layer; 6. Special cold pressing fixture; 61. Cold pressing plate body; 62. Flow channel contour boss; 63. Cooling water pipe through groove. 7. Brazing filler metal, 71. Brazing filler metal one, 72. Brazing filler metal one; 8. Solder layer. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Components, methods, etc. not specifically described in the present invention are all existing components, general components, or existing methods.

[0031] Example 1:

[0032] In Figure 1 to Figure 7 In the embodiment shown, a method to improve the heat transfer coefficient of the water-cooled plate interface is to adjust the size of the flow channel groove of the stainless steel cooling water pipe embedded in the aluminum base of the cooling plate, the embedding process, and the brazing process of the flow channel groove and the stainless steel cooling water pipe.

[0033] Vacuum brazing is a process performed in a high vacuum environment (typically with pressures below 10). -2 A precision connection technology that utilizes a brazing filler metal with a melting point lower than that of the base metal to melt, wet, and fill the gaps in the base metal, forming a strong joint through interatomic metallurgical reactions.

[0034] The interfacial heat transfer coefficient, also known as the surface heat transfer coefficient or convective heat transfer coefficient, is a core physical quantity that measures the efficiency of heat transfer at the interface between two media (usually a solid and a fluid). It is defined as the amount of heat transferred per unit time and per unit area when the temperature difference across the interface is 1 Kelvin (or 1 degree Celsius). Simply put, it characterizes the "flow" of heat across the interface; the higher the value, the stronger the heat transfer capacity.

[0035] like Figure 2 , Figure 3 As shown, a method for improving the interfacial heat transfer coefficient of a water-cooled plate includes the following steps: Step 1: The flow channel groove is machined on the aluminum base of the cooling plate; the width and depth of the cross-sectional dimensions of the flow channel groove are not equal; for example, the width can be greater than the depth, or the depth can be greater than the width, so as to leave space for the extrusion deformation of the cooling water pipe, so that the cooling water pipe fits tightly with the flow channel groove.

[0036] Step 2: A solder layer is placed at the bottom of the flow channel groove. A 0.1mm thick flow channel conformal brazing filler metal is spread inside the flow channel groove below the cooling water pipe. This wraps around the lower wall of the extruded cooling water pipe, increasing the interfacial heat transfer coefficient. The solder layer is a 0.1mm thick foil-shaped brazing filler metal, brazing paste, or solder paste. The solder layer is formed by laser cutting to conform the flow channel shape, or by coating.

[0037] Step 3: Bend the stainless steel cooling water pipe to match the flow channel groove path; then embed the stainless steel cooling water pipe into the flow channel groove along the flow channel groove path. The stainless steel cooling water pipe needs to be annealed after bending.

[0038] Step 4: See Figure 4 , Figure 5 Stainless steel cooling water pipes are cold-pressed and deformed to fit tightly into the flow channel grooves. The stainless steel cooling water pipes are cold-pressed using a cold press, resulting in a surface area 0.10-0.20mm lower than the brazing surface of the water cooling plate. The cold press precisely applies pressure to the cooling water pipes at the flow channel, causing them to embed themselves firmly into the grooves and undergo elastic deformation, resulting in better contact with the inner wall of the grooves. The lower surface of the cold-pressed cooling water pipes compared to the brazing surface of the water cooling plate facilitates the filling and wrapping of the solder around the entire outer wall of the pipe, effectively improving the interfacial heat transfer coefficient after welding. See also... Figure 8 The cold pressing is performed using a special cold pressing fixture 6, which includes an integrally formed cold pressing plate body 61. A flow channel contouring boss 62 is protruding on the cold pressing plate body. The height of the flow channel contouring boss is 0.25~0.35mm, which is used to precisely control the surface of the water pipe after cold pressing to be lower than the brazing surface, so as to avoid affecting the vacuum brazing of the water cooling plate cover and the body.

[0039] Step 5: See Figure 6 Apply solder type 2 to the stainless steel cooling water pipe, then apply solder type 1 to the brazing surface of the water cooling plate, and finally cover the cooling plate with the cover plate (see...). Figure 7The water cooling tray is pre-assembled; solder two is a 0.1mm thick flow channel conformal solder; solder one is a 0.1mm thick solder with the same shape as the brazing surface of the water cooling tray. The double-layer solder at the flow channel can better fill the gap between the water pipe and the brazing surface after cold pressing. The cooling tray cover is an integral cover with water pipe through holes and consistent with the base; or the cooling tray cover is a flow channel conformal cover.

[0040] Step 6: Weld the pre-assembled water cooling plate using vacuum brazing to complete the fabrication of the aluminum alloy water cooling plate (see...). Figure 1 ).

[0041] See Figure 1 A water-cooled plate manufactured using the aforementioned method for improving the interfacial heat transfer coefficient of a water-cooled plate, wherein the aluminum alloy water-cooled plate 1 includes a cooling plate aluminum base body 2, a stainless steel cooling water pipe 3, and a cooling plate cover plate 4; the cooling plate aluminum base body 2 is provided with a water-cooled plate brazing surface 22, and a flow channel groove 21 is formed on the water-cooled plate brazing surface 22; the stainless steel cooling water pipe 3 is embedded in the flow channel groove 21 in an extruded deformation structure, and the outer wall of the cooling water pipe 3 is covered with a solder layer 8.

[0042] Example 2:

[0043] In Figure 1 to Figure 7 In the embodiment shown, a method to improve the heat transfer coefficient of the water-cooled plate interface involves adjusting the dimensions of the flow channel groove for the stainless steel cooling water pipe embedded in the aluminum base of the cooling plate, the embedding process (adding a press cold pressing process), and the brazing process for the groove and the stainless steel cooling water pipe.

[0044] like Figure 1 As shown, the aluminum alloy water-cooled plate 1 includes a cooling plate aluminum base body 2, an embedded deformable stainless steel cooling water pipe 3, and a cooling plate cover 4. A flow channel groove 21 is formed on the cooling plate aluminum base body 2, and the location of the cooling flow channel 21 is the brazing surface 22 of the water-cooled plate. The outer wall of the cooling water pipe 3 is wrapped with a solder layer 8, which extends to the entire brazing surface 22 of the water-cooled plate.

[0045] The cooling plate aluminum base body 2 is machined with a water cooling plate U-shaped flow channel groove 21. In this embodiment, the groove opening cross-sectional dimensions of the water cooling plate U-shaped flow channel groove 21 are width × depth = 10 × 8.5 mm (the existing water cooling plate U-shaped groove opening cross-sectional dimensions are width × depth = 10 × 10 mm), and the depth is reduced by 1.5 mm.

[0046] Meanwhile, the vacuum brazing process for aluminum alloy water-cooling pans is innovated, including the following steps: Step 1: CNC precision machine a flow channel groove 21 on the surface of the aluminum base body 2 of the cooling plate. The groove is consistent with the pipeline path and larger than the pipe diameter. The cross-section of the flow channel groove 21 is U-shaped. The cross-sectional dimensions of the U-shaped flow channel groove 21 of the water cooling plate are width × depth = 10 × 8.5 mm.

[0047] Step 2: A solder layer is pre-added at the bottom of the U-shaped flow channel slot 21 of the water cooling plate along the flow channel path. In this embodiment, the solder layer is a brazing filler layer 5. The brazing filler layer 5 is a foil-shaped brazing filler with a thickness of 0.1 mm and a width of 17 mm. The brazing filler layer 5 is made of 4104 brazing filler and is made by laser cutting machine to conform the shape of the flow channel.

[0048] Step 3: Bend the stainless steel cooling water pipe 3 to match the path of the flow channel groove. After bending, the stainless steel cooling water pipe needs to be annealed to eliminate internal stress and prevent cracking. Embed the stainless steel cooling water pipe into the U-shaped flow channel groove 21 along the path of the flow channel groove 21 to achieve pre-embedding with the aluminum base body 1 of the cooling plate.

[0049] Step 4: Using a cold pressing machine, the assembled aluminum base body 2 of the cooling plate and the stainless steel cooling water pipe 3 are cold pressed using a special cold pressing fixture 6 (e.g., ...). Figure 4 , Figure 5 As shown in the figure, the cooling water pipe 3 is tightly fitted into the flow channel groove 21 after being subjected to a certain amount of compression deformation.

[0050] like Figure 7 As shown, the special cold pressing fixture 6 includes an integrally formed cold pressing plate body 61, a flow channel contoured boss 62 protruding on the cold pressing plate body 61, and a cooling water pipe through groove 63 corresponding to the inlet and outlet pipe ends of the cooling water pipe.

[0051] The height of the flow channel contour boss 62 protruding from the cold-press plate body 61 is 0.25 to 0.35 mm, ensuring that the cooling water pipe 3 after cold pressing is still 0.1 to 0.2 mm lower than the brazing surface of the water cooling plate after deformation and springback, so as to avoid affecting the assembly of the cooling plate cover plate 4 in the subsequent brazing process.

[0052] Step 5: After the aluminum base body 2 of the cooling plate and the stainless steel cooling water pipe 3 have completed the cold pressing process, chemical cleaning is performed to remove oil and oxide layer from the surface of the product, and vacuum packaging is performed after cleaning.

[0053] Step 6: Before brazing, remove the vacuum packaging and wipe the brazing surface of the water cooling plate and the brazing filler metal 7 with anhydrous ethanol and a non-woven cloth. The brazing filler metal 7 includes brazing filler metal one 71 and brazing filler metal two 72. Brazing filler metal one 71 is a 0.1mm thick foil-shaped filler metal with the same shape as the brazing surface of the water cooling plate. Brazing filler metal two 72 is a 0.1mm thick flow channel-shaped foil-shaped filler metal. In this embodiment, brazing filler metal one is used for brazing first, and brazing filler metal two is used for brazing second.

[0054] Step 7: Assembly of welded parts before welding: Spread brazing filler metal II (0.1mm thick flow channel conformal brazing filler metal) above the stainless steel cooling water pipe 3, then spread brazing filler metal I (0.1mm thick brazing filler metal with the same shape as the brazing surface) flat on the brazing surface 22 of the water cooling plate using the mounting positioning pins (e.g., Figure 6 (As shown), finally, cover the cooling tray cover 4 to complete the assembly of the pre-welding components (as shown). Figure 7 (As shown).

[0055] Step 8: After the welding parts are assembled, brazing is performed according to the vacuum brazing process to form the aluminum alloy water cooling plate 1 (e.g. Figure 1 (As shown). Vacuum brazing is an existing process.

[0056] Experiments have verified that, in this process, the stainless steel cooling water pipe 3 undergoes plastic deformation after cold pressing, allowing it to better conform to the inner wall of the U-shaped flow channel groove 21 of the water cooling plate. Secondly, the brazing filler metal added to the bottom and surface of the stainless steel cooling water pipe melts during vacuum brazing. The molten filler metal fully fills the gap between the outer wall of the stainless steel cooling water pipe and the inner wall of the flow channel groove, achieving near 100% coverage of the outer wall of the cooling water pipe (e.g., ...). Figure 1 As shown in the figure, it can effectively improve the interfacial heat transfer coefficient of the stainless steel cooling water pipes embedded in the aluminum alloy water cooling plate after vacuum brazing.

[0057] The innovative process of embedding stainless steel cooling water pipes into the water cooling plate involves adding a cold pressing process for the cooling water pipes to ensure a good fit between the stainless steel cooling water pipes and the inner wall of the U-shaped flow channel groove of the water cooling plate.

[0058] While keeping the diameter of the stainless steel cooling water pipe unchanged at Φ9.52mm, the cross-sectional dimensions of the U-shaped flow channel slot of the water cooling plate are designed to be width × depth = 10 × 8.5mm. This ensures the flow rate of the stainless steel cooling water pipe while also meeting the requirements of the internal assembly and cold pressing process of the cooling water pipe.

[0059] A layer of 4104 brazing filler metal with a thickness of 0.1mm and a width of 17mm is pre-embedded at the bottom of the U-shaped flow channel slot of the water cooling plate along the flow channel path. The brazing filler metal, which is melted at high temperature after vacuum brazing, can fill the gap between the bottom of the U-shaped flow channel slot of the water cooling plate and the stainless steel cooling water pipe.

[0060] The height of the flow channel contour boss of the special cold pressing tool 6 (0.25~0.35mm) is precisely controlled to ensure that the surface of the cooling water pipe after cold pressing is lower than the brazing surface 22 of the water cooling plate, so as to avoid affecting the vacuum brazing of the water cooling plate cover plate and the main body.

[0061] Before vacuum brazing, during the assembly process, a 0.1mm thick flow channel conformal brazing filler metal is spread above the cooling water pipe, and then the brazing filler metal on the water cooling plate welding surface is spread flat. The double layer of brazing filler metal at the flow channel can better fill the gap between the cooling water pipe and the brazing surface after cold pressing.

[0062] This method and the water-cooled plate itself improve the interfacial heat transfer coefficient of the water-cooled plate. The stainless steel cooling water pipes and the flow channel grooves of the water-cooled plate achieve a high degree of fit, effectively improving the interfacial heat transfer coefficient after vacuum brazing. The bent cooling water pipes are cold-pressed using a cold-pressing fixture, which precisely applies pressure to the cooling water pipes at the flow channel. The strong press pressure causes the cooling water pipes to be embedded within the flow channel grooves of the water-cooled plate and undergo elastic deformation, resulting in better contact with the inner wall of the flow channel grooves. This solves the problem in existing technologies where the interfacial heat transfer coefficient after vacuum brazing depends on the assembly gap between the water-cooled plate flow channel grooves and the stainless steel cooling water pipes, as well as the bending accuracy of the cooling water pipes. This leads to inconsistent interfacial heat transfer coefficients among different cooling plates after vacuum brazing, failing to meet the requirements for batch and consistent production of cooling plates, and compromising precision.

[0063] The filler metal used is 0.1mm foil-shaped 4104 alloy. Under the same welding conditions and at the same brazing process temperature, the filler metal melts fully, resulting in good filling of the gaps on both sides of the cooling water pipe. No additional adjustment of the brazing process temperature is required, and the filler wire or sheet provides good filling effect. This solves the problem in the prior art where, due to the difference in the size and shape of the filler wire (Φ1.0 filler wire fully filling both sides of the cooling water pipe after being embedded in the stainless steel cooling water pipe and not higher than the brazing surface) and the brazing conditions with the 0.1mm filler metal, the filler wire cannot fully melt under the same brazing temperature, thus failing to densely fill the gaps on both sides, which seriously affects the heat transfer efficiency of the cooling water pipe.

[0064] Example 3:

[0065] This embodiment is basically the same as the technical solution in Embodiment 2, except for the choice of solder. In this embodiment, solder paste or brazing paste is used. The paste-like solder can more fully fill the gap between the cooling water pipe and the flow channel groove of the aluminum base of the cooling plate. Since the flux in the solder paste may contaminate the vacuum system, an additional cleaning process is required.

[0066] The aluminum alloy water-cooled plate includes an aluminum base body, embedded stainless steel cooling water pipes, and a cover plate. The flow channel opening surface of the aluminum base body is the brazing surface of the water-cooled plate.

[0067] The aluminum base of the cooling plate is machined with a U-shaped flow channel groove for the water cooling plate. The cross-sectional dimensions of the U-shaped flow channel groove are width × depth = 10 × 8.5 mm (the cross-sectional dimensions of the existing U-shaped flow channel groove are width × depth = 10 × 10 mm), and the depth is reduced by 1.5 mm.

[0068] A method for improving the interfacial heat transfer coefficient of a water-cooled plate includes the following steps: Step 1: CNC precision machine a flow channel groove on the surface of the aluminum base of the cooling plate, which is consistent with the pipeline path and larger than the pipe diameter. The cross-section of the flow channel groove is U-shaped. The cross-sectional dimensions of the U-shaped flow channel groove of the water cooling plate are width × depth = 10 × 8.5 mm.

[0069] Step 2: Apply solder paste to the bottom of the U-shaped flow channel slot of the water cooling plate along the flow channel path. The solder paste is coated with a thickness of 0.1 mm and a width of 17 mm.

[0070] Step 3: Bend the stainless steel cooling water pipes to match the flow path. After bending, the stainless steel cooling water pipes need to be annealed to eliminate internal stress and prevent cracking. Embed the stainless steel cooling water pipes into the U-shaped flow channel grooves along the flow path to achieve embedding with the aluminum base of the cooling plate.

[0071] Step 4: Using a press, the assembled aluminum-based cooling plate and stainless steel cooling water pipes are cold-pressed using a special cold-pressing tool.

[0072] The special cold pressing fixture includes an integrally formed cold pressing plate body, a flow channel contour boss protruding from the cold pressing plate body, and a cooling water pipe through groove opened on the cold pressing plate body.

[0073] The protrusion of the flow channel contour boss 62 protruding from the main body of the cold-pressed plate is 0.25 to 0.35 mm, ensuring that the cooling water pipe after cold pressing is still 0.1 to 0.2 mm lower than the brazing surface of the water cooling plate after deformation and springback, thus avoiding affecting the assembly of the cover plate in the subsequent brazing process.

[0074] Step 5: After the aluminum base of the cooling plate and the stainless steel cooling water pipe have been cold-pressed, chemical cleaning is performed to remove oil and oxide layer from the product surface, and vacuum packaging is carried out after cleaning.

[0075] Step 6: Remove the vacuum packaging before brazing and wipe the brazing surface of the workpiece with anhydrous ethanol and non-woven cloth.

[0076] Step 7: Assembly of pre-welding components: Apply brazing paste (0.1mm thick, applied according to the shape of the flow channel) to the stainless steel cooling water pipe, and then apply a layer of brazing paste with a thickness of 0.1mm to the brazing surface. Lay it flat on the brazing surface of the water cooling plate by installing positioning pins. Finally, cover the water cooling plate with the cover plate to complete the assembly of pre-welding components.

[0077] Step 8: After the weldment assembly is completed, brazing is performed according to the vacuum brazing process.

[0078] Experiments have verified that, in this process, the stainless steel cooling water pipe undergoes plastic deformation after cold pressing, allowing it to better fit the inner wall of the U-shaped flow channel groove of the water cooling plate. Secondly, the brazing filler metal added to the bottom and surface of the stainless steel cooling water pipe melts during the vacuum brazing process. The melted filler metal can fully fill the gap between the outer wall of the stainless steel cooling water pipe and the inner wall of the flow channel groove, effectively improving the interfacial heat transfer coefficient of the stainless steel cooling water pipe embedded in the aluminum alloy water cooling plate after vacuum brazing.

[0079] The innovative process of embedding stainless steel cooling water pipes into the water cooling plate involves adding a cold pressing process for the cooling water pipes to ensure a good fit between the stainless steel cooling water pipes and the inner wall of the U-shaped flow channel groove of the water cooling plate.

[0080] While keeping the diameter of the stainless steel cooling water pipe unchanged at Φ9.52mm, the cross-sectional dimensions of the U-shaped flow channel slot of the water cooling plate are designed to be width × depth = 10 × 8.5mm. This ensures the flow rate of the stainless steel cooling water pipe while also meeting the requirements of the internal assembly and cold pressing process of the cooling water pipe.

[0081] A layer of solder paste with a thickness of 0.1 mm and a width of 17 mm is pre-filled at the bottom of the U-shaped flow channel slot of the water cooling plate along the flow channel path. The solder paste, which is melted at high temperature during vacuum brazing, can fill the gap between the bottom of the U-shaped flow channel slot of the water cooling plate and the stainless steel cooling water pipe.

[0082] By using the height of the contoured flow channel boss (0.25~0.35mm) of the cold pressing fixture, the surface of the cooling water pipe after cold pressing is precisely controlled to be lower than the brazing surface of the water cooling plate, so as to avoid affecting the vacuum brazing of the water cooling plate cover plate and the main body.

[0083] Before vacuum brazing, during the assembly process, a 0.1mm thick layer of brazing paste is applied above the cooling water pipe, and then another layer of brazing paste is applied to the welding surface of the water cooling plate. The double layer of brazing paste at the flow channel can better fill the gap between the cooling water pipe and the brazing surface after cold pressing.

[0084] Example 4:

[0085] This embodiment is basically the same as the technical solution of Embodiment 2 or Embodiment 3, except that the dimensions of the flow channel grooves on the aluminum base of the cooling plate are different, maximizing the deformation of the cooling water pipe without changing the flow rate. For example, the depth of the flow channel grooves on the aluminum base of the cooling plate can be made shallower and the width wider; or the cold pressing depth can be increased, increasing the deformation of the cooling water pipe and making the cooling water pipe fit more tightly with the flow channel grooves on the aluminum base of the cooling plate. However, the cold pressing depth should not be too large, otherwise the deformation of the cooling water pipe will become uncontrollable, and the defective product loss rate will increase.

[0086] Example 5:

[0087] This embodiment is basically the same as the technical solution of Embodiment 1, Embodiment 2, Embodiment 3, or Embodiment 4, except that the shape of the cooling plate cover adopts a contoured structure similar to the flow channel path, which can reduce the brazing area and ensure that the material properties of the unbrazed part are better than those of the brazed part. However, during the processing, it is necessary to ensure the accuracy of the cooling plate cover with the flow channel contoured structure, and during the assembly process, it is necessary to ensure the fit clearance between it and the aluminum base body of the cooling plate, and ensure that the brazing effectively fills the fit clearance.

[0088] Example 6:

[0089] This embodiment is basically the same as the technical solution of Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, or Embodiment 5, except that a different brazing solder is used, such as 4004 solder. Using different solders, especially those with high Mg content, can enhance the initial "oxide film removal" ability. During the manufacturing process, it is necessary to strictly follow the process requirements, and the temperature and time must be precisely controlled to avoid excessive and concentrated Mg volatilization, thus preventing brazing failure or premature Mg depletion.

[0090] The above embodiments describe a method for improving the interfacial heat transfer coefficient of a water-cooled plate and the water-cooled plate itself: The bent cooling water pipes are cold-pressed using a cold-pressing fixture, which precisely applies pressure to the cooling water pipes at the flow channel. The powerful press pressure causes the cooling water pipes to be embedded in the flow channel grooves of the water-cooling plate and to undergo elastic deformation, resulting in better contact with the inner wall of the flow channel grooves. The high degree of fit between the stainless steel cooling water pipes and the flow channel grooves of the water-cooling plate ensures the temperature stability and consistency of the water-cooling plate, effectively improving the interface heat transfer coefficient after vacuum brazing.

[0091] This invention solves the problem in existing technologies where the interface heat transfer coefficient after vacuum brazing depends on the assembly gap between the water cooling plate flow channel slot and the stainless steel cooling water pipe, as well as the bending accuracy of the cooling water pipe. This results in inconsistent interface heat transfer coefficients for different cooling plates after vacuum brazing, which cannot meet the requirements for batch and consistent production of cooling plates.

[0092] The filler metal is 0.1mm in size, the welding conditions are the same, and the filler metal melts fully under the same brazing process temperature. The gap between the two sides of the cooling water pipe is filled well, and no additional adjustment of the brazing process temperature is required, which effectively improves the heat transfer efficiency of the cooling water pipe.

Claims

1. A method for improving the interfacial heat transfer coefficient of a water-cooled plate, characterized in that... Includes the following steps: S1: The flow channel groove machined on the aluminum base of the cooling plate; S2: A solder layer is set at the bottom of the flow channel slot; S3: Bend the stainless steel cooling water pipe to match the path of the flow channel groove; and embed the stainless steel cooling water pipe into the flow channel groove along the path of the flow channel groove. S4: The stainless steel cooling water pipe is squeezed and deformed by cold pressing process and then tightly fitted into the inside of the flow channel groove. S5: Place solder 2 on the stainless steel cooling water pipe, then place solder 1 on the brazing surface of the water cooling plate, and finally cover the cooling plate to complete the pre-assembly of the water cooling plate. S6: The pre-assembled water cooling plate is welded using a vacuum brazing process to complete the fabrication of the aluminum alloy water cooling plate.

2. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to claim 1, characterized in that: The width and depth of the groove cross-section in step 1 are not equal.

3. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to claim 1, characterized in that: In step 2, the solder layer is a foil-shaped brazing filler metal or brazing paste with a thickness of 0.1 mm; the solder layer is made by laser cutting to conform the flow channel shape, or the solder layer is formed by coating.

4. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to claim 1, characterized in that: In step 3, the stainless steel cooling water pipes need to be annealed after bending.

5. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to claim 1, characterized in that: In step 4, the stainless steel cooling water pipe is cold-pressed using a cold press. After cold pressing, the surface of the cooling water pipe is 0.10~0.20mm lower than the brazing surface of the water cooling plate.

6. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to claim 1, characterized in that: In step 4, a special cold pressing tool (6) is used for cold pressing. The special cold pressing tool (6) includes an integrally set cold pressing plate body (61), and a flow channel contouring boss (62) is provided on the cold pressing plate body (61). The height of the flow channel contouring boss (62) is 0.25~0.35mm.

7. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to claim 1, characterized in that: In step 5, solder two is set as a flow channel conformal solder with a thickness of 0.1mm; solder one is set as a solder with a thickness of 0.1mm and the same shape as the brazing surface of the water cooling plate.

8. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to any one of claims 1 to 7, characterized in that: The solder layer, solder two, and solder one are solders of the same material, namely 4104 solder or 4004 solder.

9. The method for improving the interfacial heat transfer coefficient of a water-cooled plate according to any one of claims 1 to 7, characterized in that: The cooling tray cover in step 5 is an integral cover with water pipe through holes and consistent with the base; or the cooling tray cover is a flow channel conformal cover.

10. A water-cooled plate manufactured using the method for improving the interfacial heat transfer coefficient of a water-cooled plate according to any one of claims 1 to 9, characterized in that: The aluminum alloy water cooling plate (1) includes an aluminum base body (2), a stainless steel cooling water pipe (3), and a cooling plate cover (4); the aluminum base body (2) of the cooling plate is provided with a brazing surface (22) of the water cooling plate, and a flow channel groove (21) is opened on the brazing surface (22) of the water cooling plate. The stainless steel cooling water pipe (3) is embedded in the flow channel groove (21) in an extruded deformation structure, and the outer wall of the cooling water pipe (3) is covered with a solder layer (8).

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