Preparation process of a direct contact heat spreader of a rolled heat pipe

Abstract

The application relates to a preparation process of a rolling hot-pipe direct-contact heat spreader and relates to the technical field of hot-pipe heat spreaders. The preparation process comprises the following steps: base plate manufacturing: a plurality of parallelly-arranged mounting grooves are formed on the upper surface of a base plate, and the mounting grooves are matched with the outer contour of a heat pipe assembly; heat pipe assembly manufacturing: a copper-based sintered wick is sintered in the inside, and the copper-based sintered wick comprises a plurality of evaporation sections and condensation sections, and the plurality of evaporation sections are matched with the mounting grooves; after vacuumizing, super-pure water with a specified weight is filled; assembly and welding; fin assembly. The application is characterized in that the heat pipe assembly is physically closely attached to the mounting grooves through rolling, and metallurgical bonding is formed through welding, so that the interface contact thermal resistance is greatly reduced compared with traditional pasting and welding; and the high-efficiency phase-change heat transfer of the copper-based sintered wick is matched, so that the heat dissipation effect is improved.

Description

Technical Field

[0001] This application relates to the technical field of heat pipe radiators, and in particular to a manufacturing process for a rolled heat pipe direct contact radiator. Background Technology

[0002] With the rapid increase in the computing power of electronic devices, the power consumption and heat generation of their core chips are increasing day by day, placing higher demands on heat dissipation performance. Heat pipe radiators are widely used due to their efficient heat conduction capabilities.

[0003] Traditional heat pipe radiators typically employ a "heat pipe embedded in a copper base" structure, generally using an indirect contact structure of "heat pipe-heat transfer medium-substrate". Radiator manufacturing generally follows these methods:

[0004] First, the copper-filled process: The heat pipe is passed through the heat sink fins and fixed by soldering. In this method, there is a gap between the heat pipe and the base that contacts the chip, requiring secondary heat transfer through a thermally conductive medium (solder). This introduces additional contact thermal resistance, and during the soldering process, liquid solder is prone to overflow due to capillary action, covering the intended area where the heat pipe and chip are in direct contact, forming a layer of solder with low thermal conductivity, which actually increases the thermal resistance.

[0005] Second, direct-touch heat pipe process: The heat pipe is directly flattened and attached to the bottom of the heat sink base, making direct contact with the heat source. Although direct-touch heat pipe heat sinks can reduce the number of contact points, existing direct-touch structures mostly use interference fit between the heat pipe and the substrate, which has problems such as difficult assembly, easy deformation of the heat pipe, and insufficient thermal contact area. Therefore, there is an urgent need for a rolling heat pipe direct-touch heat sink manufacturing process to ensure that the heat sink can stably and effectively improve the heat dissipation effect. Summary of the Invention

[0006] To ensure a stable and effective improvement in heat dissipation, this application provides a manufacturing process for a roll-formed heat pipe direct-contact heat sink.

[0007] This application provides a manufacturing process for a rolled heat pipe direct-contact radiator, which employs the following technical solution:

[0008] A manufacturing process for a rolled heat pipe direct-contact radiator includes the following steps:

[0009] Substrate fabrication: Several parallel mounting grooves are formed on the upper surface of the substrate, and the mounting grooves match the outer contour of the heat pipe assembly.

[0010] Heat pipe assembly fabrication: It consists of several copper gravity heat pipes with a sintered copper-based liquid wick inside, and includes multiple evaporation sections and condensation sections. The multiple evaporation sections are matched with the mounting groove. After vacuuming, a specified weight of ultrapure water is injected and the assembly is sealed to form a gravity heat pipe. The weight of ultrapure water is calculated according to the liquid injection volume formula.

[0011] Assembly and welding: The evaporation section is welded to the mounting groove, and the heat pipe assembly is rolled flat using a roller press;

[0012] Fin assembly: Fins are made by stamping aluminum plates of specified thickness and then fixed to the condensation section by brazing.

[0013] By adopting the above technical solution, the heat pipe assembly is fabricated by including multiple evaporation sections and condensation sections. After vacuuming, ultrapure water is filled in. The evaporation sections are embedded in multiple mounting grooves on the substrate, and then rolled and welded by a roller press. Finally, the fins are fixedly connected to the condensation sections. This achieves multi-point, large-area direct contact heat conduction in a single tube. The heat source heat is conducted to each evaporation section through the low resistance of the substrate. The sintered liquid wick inside the heat pipe provides capillary force, and the phase change of the working fluid conducts heat to the outer condensation section. The bent and exposed condensation section increases the heat exchange area through fins, and quickly dissipates heat by convection, achieving efficient and uniform heat dissipation from a large surface source.

[0014] Rolling ensures a tight physical fit between the heat pipe assembly and the mounting groove, while welding creates a metallurgical bond. This dual action significantly reduces the interfacial contact thermal resistance compared to traditional surface mounting and welding. Combined with the efficient phase change heat transfer of the copper sintered wick, the heat dissipation effect is further improved.

[0015] Based on the precise matching of the working fluid and wick ratio using the liquid injection formula, and adapting to the internal cavity deformation caused by bending and rolling, the working fluid of the finished heat pipe is always in the optimal state. The heat transfer limit and start-up performance are not affected by the processing technology, the performance consistency of batch products is greatly improved, and the heat dissipation effect is enhanced.

[0016] The evaporation section focuses on low thermal resistance conduction and structural bonding, while the condensation section focuses on large-area convective heat transfer. Both sections adopt the optimal process scheme, avoiding the drawbacks of insufficient heat transfer area in the condensation section in the traditional "integral embedded groove and unified through-fin" scheme. This maximizes heat dissipation performance under the same material cost, greatly improving the heat dissipation effect.

[0017] Optionally, the assembly welding step includes:

[0018] Rolling: The evaporation section is embedded into the mounting groove, and then the substrate is placed on the tooling fixture for clamping and positioning. The roller press rolls the evaporation section flat.

[0019] Welding: Weld the heat pipe assembly after rolling to form a weld layer between the evaporation section and the mounting groove.

[0020] By adopting the above technical solution, during the rolling process, the multiple evaporation sections undergo slight plastic deformation simultaneously under the extrusion pressure, and the outer wall and the inner wall of the installation groove are in zero-distance contact, completely eliminating the interface gap and ensuring better contact between the two. Subsequently, the welding process penetrates and forms a metallurgical connection layer on the tightly fitted interface, which will not cause problems such as insufficient solder filling or false welding due to excessive gaps, and finally forms a dual low-resistance interface of "physical bonding and metallurgical bonding".

[0021] First, roll forming eliminates interface gaps before welding, allowing solder to penetrate the entire bonding surface evenly. This completely avoids problems such as incomplete welds, false welds, and localized solder loss, further improving the weld yield. It is especially suitable for multi-interface welding scenarios with multiple bent heat pipes, ensuring the welding bonding rate of all evaporation sections simultaneously. Roll forming achieves zero-distance physical bonding of the interface, and coupled with the metallurgical thermal conductivity of the welding layer, heat conduction is smoother, resulting in superior overall heat dissipation performance of the radiator.

[0022] Optionally, the assembly welding step includes:

[0023] Welding: The evaporation section is embedded into the mounting groove, and the substrate is placed on the welding fixture. Reflow soldering is used to weld the substrate to form a weld layer between the evaporation section and the mounting groove.

[0024] Rolling: The substrate is then placed on the rolling fixture, and the product temperature is maintained at 40-50℃. The rolling press rolls the evaporation section flat.

[0025] By adopting the above technical solution, the reflow soldering first welds and fixes the multiple evaporation sections to the substrate, avoiding heat pipe displacement and springback misalignment during the rolling process; the 40-50℃ heat preservation state keeps the copper heat pipe and the welding layer in the optimal plasticity range, reducing the material yield strength and increasing toughness, making the welding layer less prone to brittle fracture and detachment during rolling and shaping, while gradually releasing the residual stress generated by welding, avoiding deformation and warping of the product due to stress release after long-term use.

[0026] At room temperature, the weld layer is brittle and prone to micro-cracks and failure during roll forming. Roll forming at 40-50℃ significantly improves the plasticity of the weld layer and greatly reduces the failure rate of weld layer cracking during roll forming. This solves the core pain point of the "weld first, roll later" process and is especially suitable for multi-weld surface scenarios with multiple bending heat pipes, significantly improving product reliability.

[0027] After reflow soldering forms a complete and continuous weld layer, it is then rolled and shaped. The interface weld strength is not affected by the rolling process. The rolling process further compacts the interface, resulting in a final product with both structural strength and thermal conductivity. Furthermore, the heat pipe does not shift laterally or spring back during the rolling process. The positional accuracy and parallelism of the multi-segment evaporation sections are far superior to the roll-then-soldering process, making it suitable for the needs of high-reliability industrial-grade products. At the same time, the warm rolling process releases residual welding stress simultaneously, preventing substrate warping and flatness degradation caused by slow stress release after the product leaves the factory, thus improving product quality and heat dissipation.

[0028] Optionally, the substrate is prepared by: using an AL6061 aluminum block, machining 8 parallel mounting grooves by CNC milling, with a groove radius of 2.55mm, a groove depth of 9.75mm, and a length of 118mm, and plating the entire aluminum base plate with chemical nickel with a film thickness of 1.2um.

[0029] By adopting the above technical solution, the installation groove radius is slightly smaller than the heat pipe radius, and the groove depth is slightly smaller than the heat pipe radius, forming an interference fit. After roll forming, the heat pipe and the installation groove can achieve a tight fit on the entire circumference. The chemical nickel plating improves the wettability of the aluminum substrate and the solder, ensuring the welding quality. The 0.25mm wall thickness heat pipe assembly has both bending plasticity and roll forming deformation capability, making it less prone to crushing and easier to shape.

[0030] The dimensions of the mounting groove and the heat pipe assembly are precisely matched, resulting in a larger contact area after rolling. This eliminates issues such as localized gaps and poor fit, minimizing interfacial thermal resistance and achieving optimal heat transfer efficiency. It also accommodates the embedding requirements of multi-segment bent heat pipes, ensuring uniform fit across all evaporation sections and improving the product's heat dissipation performance.

[0031] Optionally, the weight of the ultrapure water is W1, and the injection volume formula is: W1=(L-L0)×S×P×ρ×K;

[0032] In the formula: L is the total length of the heat pipe assembly; L0 is the total length of the sealing sections at both ends of the heat pipe assembly; L-L0 is the effective working length of the heat pipe assembly; S is the annular cross-sectional area of ​​the sintered copper-based wicking core, which is obtained by subtracting the cross-sectional area of ​​the vapor chamber from the cross-sectional area of ​​the inner hole of the heat pipe assembly; P is the porosity of the wicking core, which is 55%; ρ is the density of ultrapure water; K is the safety margin factor, which is 1.05~1.1.

[0033] By adopting the above technical solution, the formula accurately calculates the theoretical optimal working fluid mass based on the volume and porosity of the wick, ensuring that the working fluid just fills the pores of the wick, achieving the best capillary reflux and phase change heat transfer effect. The quantitative formula precisely matches the wick structure and heat pipe size, and the working fluid filling amount just meets the phase change cycle requirements. It will not dry out due to insufficient working fluid and decrease the heat transfer limit, nor will it increase the liquid resistance and slow down the start-up due to excessive working fluid, thus improving the heat dissipation effect.

[0034] Optionally, the weight of ultrapure water to be added after vacuuming is W2 = W1 + W1 * 20%.

[0035] By adopting the above technical solution, an additional 20% compensation is added to offset the double reduction in the inner volume of the heat pipe caused by bending and flattening and roll forming, ensuring that the working fluid inside the heat pipe is still in the optimal ratio after roll forming, the steam chamber space is sufficient, and the heat transfer limit does not decrease.

[0036] Optionally, the heat pipe assembly is formed by a bending mechanism. The substrate is mounted on the bending mechanism for positioning. The bending mechanism bends the heat pipe assembly to form an evaporation section embedded with multiple mounting grooves and a condensation section connected to the evaporation section. The bending mechanism presses against the evaporation section for positioning. Then, after vacuuming, ultrapure water is filled in, and finally welding and rolling are performed.

[0037] By adopting the above technical solution, the mounting groove of the substrate is used as the bending positioning reference. The size and position of the evaporation section after bending are completely matched with the mounting groove, avoiding the dimensional errors and assembly difficulties caused by "bending first and then assembling". At the same time, the bending mechanism presses against the evaporation section for positioning, so that the evaporation section fits better with the mounting groove. The substrate simultaneously serves as a bending tool and a heat dissipation substrate. The bending positioning and subsequent assembly are completed in one clamping, reducing intermediate transfer and repeated positioning errors, making the evaporation section fit better with the mounting groove, and further improving the heat dissipation effect.

[0038] The heat pipe assembly is evacuated and then filled with ultrapure water. The mounting groove and the pressing mechanism can support and position the evaporation section. Compared with filling with ultrapure water and then installing it into the mounting groove, this reduces the risk that the evaporation section will deform and be difficult to fit into the mounting groove after filling with ultrapure water, thereby further improving the heat dissipation effect.

[0039] The evaporation sections are directly bent based on the substrate and the mounting groove. The spacing and parallelism of the evaporation sections match the mounting groove 100%, completely avoiding the dimensional deviation caused by independent bending. The evaporation sections can be perfectly embedded into the mounting groove without correction during assembly, greatly improving assembly efficiency and bonding quality.

[0040] Optionally, the bending mechanism includes:

[0041] A bending seat is installed on the machine body and has a snap-fit ​​groove that engages with the evaporation section.

[0042] A positioning plate is installed on the machine body, and the heat pipe assembly is positioned by abutting against the positioning plate and the mounting groove;

[0043] The pressure assembly is installed on the body and presses vertically downward against the heat pipe assembly for positioning;

[0044] The bending head pushes the heat pipe assembly to bend and form the condensation section.

[0045] By adopting the above technical solution, the substrate is embedded in the bending seat slot to complete the reference positioning, the heat pipe assembly is placed in the mounting groove, and the end abuts against the positioning plate to complete the axial positioning; the pressing component presses down to tighten all evaporation sections and fixes the position of the heat pipe assembly; the bending head pushes the exposed part of the heat pipe assembly to bend at a set angle to form a condensation section at a set angle with the evaporation section, ensuring that the bending angle and section length of all heat pipes are completely consistent.

[0046] The triple positioning system—base plate clamping, end positioning, and evaporator section clamping—ensures that the heat pipe assembly does not shift or spring back during bending, achieving bending accuracy far exceeding that of ordinary bending fixtures. The pressure assembly simultaneously clamps all evaporator sections, ensuring uniform force distribution and no shifting during bending. All bending angles of single or multi-segment heat pipes are completely consistent, significantly improving dimensional uniformity in batch products and enhancing heat dissipation.

[0047] Optionally, the pressure-absorbing component includes:

[0048] The pressure seat is slidably mounted on the body along the direction close to or away from the substrate, and has multiple pressure grooves that match the heat pipe assembly;

[0049] The pressure element is used to drive the pressure seat to move.

[0050] By adopting the above technical solution, when the pressure seat moves down, multiple pressure grooves simultaneously engage with the upper surface of the corresponding copper tubes, achieving synchronous pressing and positioning of multiple / multi-segment copper tubes; the pressure grooves are adapted to the outer contour of the heat pipe assembly, resulting in a large contact area and stress dispersion during pressing, preventing damage to the heat pipe assembly and internal liquid wick; the overall sliding drive structure ensures uniform and consistent pressing force at all points, improving the product's heat dissipation effect.

[0051] Optionally, the bending seat is slidably mounted on the machine body, the roller press is located on the machine body, and the bending seat moves the drive plate to the pressing assembly or the roller press.

[0052] By adopting the above technical solution, the initial mounting base is located at the bending station, completing the substrate clamping, heat pipe positioning and bending forming; after bending, the mounting base moves linearly along the guide rail to the rolling station, and after positioning, it directly performs the rolling and leveling operation; throughout the entire process, the workpiece is always fixed on the bending base, without the need for disassembly, transfer and secondary clamping.

[0053] Bending and rolling share the same clamping datum, eliminating the accumulation of positioning errors from secondary clamping. This significantly improves the positional accuracy and flatness of the evaporation section, greatly optimizes product dimensional consistency, and completely solves the problem of error superposition in sub-processing, thereby improving the product's heat dissipation effect.

[0054] In summary, this application includes at least one of the following beneficial technical effects:

[0055] 1. By rolling, the heat pipe assembly is physically and tightly fitted to the mounting groove, and welding is formed to form a metallurgical bond. Under the dual effect, the interfacial contact thermal resistance is greatly reduced compared with traditional surface mounting and welding. Combined with the efficient phase change heat transfer of the copper sintered liquid wick, the heat dissipation effect is improved.

[0056] 2. By precisely matching the working fluid and wick ratio based on the injection volume formula, and adapting to the internal cavity deformation caused by bending and rolling, the working fluid of the finished heat pipe is always in the optimal state. The heat transfer limit and start-up performance are not affected by the processing technology, the performance consistency of batch products is greatly improved, and the heat dissipation effect is enhanced.

[0057] 3. By focusing on low thermal resistance conduction and structural bonding in the evaporation section and focusing on large-area convective heat transfer in the condensation section, and by adopting the optimal process scheme for each section, the drawback of insufficient heat transfer area in the condensation section in the traditional "integral embedded groove and unified through fin" scheme is avoided. Under the same material cost, the heat dissipation performance is maximized, which greatly improves the heat dissipation effect.

[0058] 4. After forming a complete and continuous weld layer through reflow soldering, the interface weld strength is not affected by the rolling process. The rolling process further compacts the interface, resulting in a final product with both structural strength and thermal conductivity. Furthermore, the heat pipe does not experience lateral displacement or springback during the rolling process. The positional accuracy and parallelism of the multi-segment evaporation sections are far superior to the pre-rolling and post-soldering process, making it suitable for the requirements of high-reliability industrial-grade products. At the same time, the warm rolling process releases residual welding stress simultaneously, preventing substrate warping and flatness degradation caused by slow stress release after the product leaves the factory, thus improving product quality and heat dissipation. Attached Figure Description

[0059] Figure 1 This is a three-dimensional structural schematic diagram of Embodiment 1 of the rolled heat pipe direct contact radiator;

[0060] Figure 2 This is a schematic diagram of the substrate structure in Embodiment 1 of the roll-up heat pipe direct contact radiator;

[0061] Figure 3 This is a schematic diagram of the body and bending mechanism in Embodiment 5 of the rolled heat pipe direct contact radiator;

[0062] Figure 4 yes Figure 3 Enlarged schematic diagram of part A in the middle.

[0063] Reference numerals: 1. Body; 11. Mounting base; 2. Bending mechanism; 21. Bending seat; 22. Positioning plate; 23. Snap-fit ​​groove; 3. Pressing assembly; 31. Pressing seat; 32. Pressing component; 33. Pressing groove; 5. Base plate; 51. Mounting groove; 6. Heat pipe assembly; 61. Evaporation section; 62. Condensation section; 7. Fins. Detailed Implementation

[0064] The following provides a further detailed description of this application.

[0065] This application discloses a manufacturing process for a rolled heat pipe direct contact radiator.

[0066] Example 1, referring to Figures 1-2 The manufacturing process of a direct-contact heat sink with rolled heat pipes includes the following steps:

[0067] Substrate 5 fabrication: AL6061 aluminum block is selected and CNC milling is used to obtain 10 parallel mounting grooves 51 with a radius of 1.9mm, a groove depth of 6.5mm, and a length of 118mm; the aluminum base plate is plated with chemical nickel with a film thickness of 1.2um.

[0068] Fabrication of heat pipe assembly 6: Composed of several copper gravity heat pipes, using seamless copper pipes with an outer diameter that matches the radius of the mounting groove 51 and a wall thickness of 0.25mm. The inner copper-based wicking core is sintered, and includes multiple interconnected evaporation sections 61 and condensation sections 62. The multiple evaporation sections 61 match the mounting groove 51. The evaporation sections 61 and condensation sections 62 are first formed by bending. After vacuuming, a specified weight of ultrapure water is injected, and the assembly is sealed to form a gravity heat pipe. The weight of the ultrapure water is calculated according to the injection volume formula.

[0069] The formula for the injection volume is as follows: The theoretical injection weight W1 of ultrapure water is calculated by the following formula: W1=(L-L0)×S×P×ρ×K; Where: L is the total length of heat pipe assembly 6; L0 is the total length of the sealing sections at both ends of heat pipe assembly 6, L0 can be 10, L-L0 is the effective working length of heat pipe assembly 6; S is the annular cross-sectional area of ​​the sintered copper-based wicking core, which is obtained by subtracting the cross-sectional area of ​​the vapor chamber from the cross-sectional area of ​​the inner hole of heat pipe assembly 6; P is the porosity of the wicking core, which is taken as 55%; ρ is the density of ultrapure water; K is the safety margin factor, which is taken as 1.05~1.1.

[0070] Assembly and welding: The evaporation section 61 is welded to the mounting groove 51, and the heat pipe assembly 6 is rolled flat by a roller press. The roller press is a roller pressing structure in the prior art, which will not be described in detail here.

[0071] The assembly and welding steps include: Rolling: The evaporation section 61 is embedded into the mounting groove 51, and the substrate 5 is placed on the tooling fixture for clamping and positioning. The roller press rolls the evaporation section 61 flat. The parameters of the roller press are: rolling speed 200mm / s and each pressing distance 0.05mm.

[0072] Welding: The heat pipe assembly 6 after rolling is welded using reflow soldering to form a weld layer between the evaporation section 61 and the mounting groove 51.

[0073] Fin 7 assembly: Select aluminum plates of specified thickness and stamp them to form fins 7 with a height of 15.6mm and a thickness of 0.3mm. They are fixed to the condensation section 62 by brazing. The spacing between fins 7 is 1.5mm, and a total of 64 fins 7 are assembled.

[0074] The working principle of this application embodiment is as follows:

[0075] Ten parallel mounting grooves 51 are machined from an aluminum base plate using CNC milling, and the entire aluminum base plate is plated with electroless nickel. Seamless copper tubes are selected, with a sintered copper-based wicking core inside, and include multiple evaporation sections 61 and condensation sections 62. After vacuuming, a specified weight of ultrapure water is injected, and the tubes are sealed to form a heat pipe assembly 6. The evaporation sections 61 are embedded into the mounting grooves 51, and the heat pipe assembly 6 is rolled flat using a roller press. The rolled heat pipe assembly 6 is then welded to form a weld layer between the evaporation sections 61 and the mounting grooves 51. The high-fin 7 is then fixedly connected to the condensation section 62 to obtain the radiator. Rolling ensures that the evaporation sections 61 and the mounting grooves 51 are physically and tightly bonded, and the welding forms a metallurgical bond. Under the dual effect, the interfacial contact thermal resistance is greatly reduced compared to traditional surface mounting welding. Combined with the efficient phase change heat transfer of the sintered copper wicking core, the heat dissipation effect is further improved.

[0076] Example 2, refer to Figures 1-2 The difference between this embodiment and Embodiment 1 is that the assembly and welding steps include:

[0077] Welding: The evaporation section 61 is embedded into the mounting groove 51, and the substrate 5 is placed on the welding fixture. Reflow soldering is used to weld the substrate 61 to form a weld layer between the evaporation section 61 and the mounting groove 51.

[0078] Rolling: The substrate 5 is then placed on the rolling fixture for clamping and positioning, maintaining the product temperature at 40-50℃. The rolling press rolls the evaporation section 61 flat.

[0079] The working principle of this application embodiment is as follows:

[0080] The evaporation section 61 is welded to the mounting groove 51 for initial positioning. Then, before the weld layer is completely solidified, the product is kept at an ambient temperature of 40-50℃ and rolled by a roller press to make the weld layer more uniform. This makes the connection between the heat pipe assembly 6 and the mounting groove 51 more stable, improving the heat dissipation effect and stability of the radiator.

[0081] Example 3, referring to Figure 2 The difference between this embodiment and embodiment 2 is that eight parallel mounting grooves 51 are machined by CNC milling, with a radius of 2.55 mm and a groove depth of 9.75 mm; and seamless copper tubes with an outer diameter of 8 mm are used to prepare the heat pipe assembly 6.

[0082] Example 4, refer to Figure 1 The difference between this embodiment and embodiment 2 is that the weight of ultrapure water that needs to be added after vacuuming is W2 = W1 + W1 * 20%, which increases the amount of pure water by 20% compared to the calculation formula, thus improving the heat dissipation effect of the radiator.

[0083] Example 5, refer to Figure 3 and Figure 4 The difference between this embodiment and embodiment 2 is that the heat dissipation substrate 5 is mounted on the bending mechanism 2 for positioning. The bending mechanism 2 bends the heat pipe assembly 6 to form an evaporation section 61 embedded with multiple mounting grooves 51 and a condensation section 62 connected to the evaporation section 61. The bending mechanism 2 presses against the evaporation section 61 for positioning. Then, after vacuuming, ultrapure water is filled in, and finally welding and rolling are performed.

[0084] The bending mechanism 2 includes a bending seat 21, a positioning plate 22, a pressing component 3, and a bending head. The bending seat 21 is horizontally slidably mounted on the upper surface of the body 1, and the sliding direction is along the length of the body 1. An electric push rod for driving the bending seat 21 to move is fixedly mounted on the upper surface of the body 1. A snap-fit ​​groove 23 is opened on the upper surface of the bending seat 21, and the base plate 5 is vertically snapped and mounted on the snap-fit ​​groove 23 for positioning. The positioning plate 22 is fixedly mounted on the upper surface of one end of the body 1, and the heat pipe assembly 6 is positioned against the positioning plate 22 and placed on the mounting groove 51 to form the evaporation section 61.

[0085] A mounting base 11 is fixedly installed on the upper surface of the body 1. The pressing component 3 is set on the mounting base 11 and presses vertically downward against the heat pipe assembly 6 for positioning. A bending head is set on the body 1 and is used to push the heat pipe assembly 6 located outside the mounting groove 51 to bend into a condensing section 62 according to a set angle. The bending head is a structure in the prior art, and the bending angle is set as needed, which will not be described in detail here.

[0086] The pressing assembly 3 includes a pressing seat 31 and a pressing member 32. The pressing seat 31 is vertically slidably mounted on the side wall of the mounting base 11 and located above the bending base 21. Multiple pressing grooves 33 matching the heat pipe assembly 6 are spaced apart on the lower surface of the pressing seat 31. The pressing seat 31 is located directly above the substrate 5. The pressing member 32 is an electric push rod or a cylinder. The pressing member 32 is fixedly mounted on the top of the mounting base 11, and the piston rod is vertically downward and fixedly connected to the pressing seat 31.

[0087] The roller press is fixedly installed on the upper surface of the machine body 1 and is located on the side of the mounting base 11 away from the positioning block 22. The bending base 21 moves the driving plate 5 to the pressing assembly 3 to clamp and bend, or the driving plate 5 moves to the roller press to roll and flatten the evaporation section 61.

[0088] The substrate 5 is snapped into the snap-fit ​​groove 23 for positioning. The heat pipe assembly 6 is pre-pressed to form a bent state. The heat pipe assembly 6 is then placed against the positioning plate 22 for positioning and placed on the mounting groove 51. The pressing seat 31 moves down and presses against multiple heat pipe assemblies 6 for positioning. The bending head starts to bend the heat pipe assembly 6 located outside the mounting groove 51. After bending, the pressing seat 31 moves up away from the heat pipe assembly 6. The bending seat 21 moves to drive the substrate 5 and the heat pipe assembly 6 to the roller press for rolling and subsequent welding.

[0089] The working principle of this application embodiment is as follows:

[0090] The substrate 5 is snapped into the snap-fit ​​groove 23 for positioning. The heat pipe assembly 6 is pre-pressed to form a bent state. The heat pipe assembly 6 is then pressed against the positioning plate 22 and placed on the mounting groove 51. The pressing seat 31 presses against multiple heat pipe assemblies 6 for positioning. The bending head is activated to bend the heat pipe assembly 6, and the pressing seat 31 moves away from the heat pipe assembly 6. The bending seat 21 drives the heat pipe assembly 6 to the roller press for rolling and subsequent welding, which improves the product quality and heat dissipation effect.

[0091] Reference Figures 1-4 The parameters of the heat sinks produced in the above embodiments were tested, and the test data are as follows.

[0092] Test conditions: The heat transfer performance of the rolled heat pipe direct contact radiators prepared in each embodiment was tested under the same conditions: heating power 250W, ambient temperature 25℃, forced air cooling (wind speed 3m / s), and heat source size 30mm×30mm. The test method refers to GB / T8446.2-2022 "Radiators for Power Semiconductor Devices - Part 2: Methods for measuring thermal resistance and flow resistance".

[0093]

[0094] Data Analysis:

[0095] 1. Influence of Process Sequence (Example 1 vs. Example 2): Example 1 uses "rolling before welding," resulting in a system thermal resistance of 0.108℃ / W; Example 2 uses "reflow soldering before rolling (40-50℃ temperature control)," reducing the thermal resistance to 0.088℃ / W, a decrease of 18.5%. The main reason is that the weld layer formed by the initial welding is compacted and densified during the subsequent rolling process. Simultaneously, the rolling pressure helps eliminate residual welding stress, enabling molecular-level tight contact between the outer wall of the heat pipe assembly 6 and the inner wall of the mounting groove 51. Furthermore, the reflow soldering process in Example 2 increases the shear strength of the weld layer from 24.5MPa to 29.2MPa, and reduces the interface temperature difference from 3.5℃ to 2.3℃.

[0096] 2. Influence of the Number and Size of Mounting Grooves 51 (Example 2 vs. Example 3): Example 3 uses 8 mounting grooves 51 (radius 2.55mm, groove depth 9.75mm) instead of the 10 mounting grooves 51 (radius 1.9mm, groove depth 6.5mm) in Example 2. The number of heat pipe assemblies 6 is reduced, but the contact area between a single heat pipe assembly 6 and the substrate 5 is increased. Experimental results show that the system thermal resistance increases from 0.088℃ / W to 0.093℃ / W, and the maximum heat dissipation power decreases from 368W to 355W. This indicates that, with a similar total contact area, increasing the number of heat pipe assemblies 6 (i.e., increasing the heat transfer path) is more effective in improving heat dissipation performance than increasing the size of a single heat pipe assembly 6.

[0097] 3. Impact of Optimized Liquid Filling Amount (Example 2 vs. Example 4): Example 4 increases the liquid filling amount by 20% (W2 = W1 + W1 × 20%) compared to Example 2, further reducing the system thermal resistance to 0.082℃ / W and increasing the maximum heat dissipation power to 378W. Appropriately increasing the liquid filling amount ensures that the evaporation section 61 will not "dry out" under heavy load, thus improving the heat transfer limit of the heat pipe assembly 6. However, it should be noted that more liquid filling is not always better; excessive liquid filling will occupy the steam chamber space, which is detrimental to steam transport.

[0098] 4. Impact of bending positioning accuracy (Example 4 vs. Example 5) - Example 5 is superior to Example 4 in all aspects: Example 5 uses the bending mechanism 2 (multiple positioning of positioning plate 22, snap-fit ​​groove 23, and pressure seat 31) to accurately position the heat pipe assembly 6 before liquid filling and welding. The system thermal resistance is further reduced to 0.076℃ / W, which is about 7.3% lower than that of Example 4 (0.082℃ / W); the maximum heat dissipation power reaches 392W, which is about 3.7% higher than that of Example 4 (378W).

[0099] Example 5 is superior to Example 4 in every way because:

[0100] Eliminating assembly internal stress: The bending mechanism 2 rigidly positions the substrate 5 through the snap-fit ​​groove 23, and the multiple pressing grooves 33 on the pressing seat 31 independently constrain each heat pipe assembly 6, ensuring that all evaporation sections 61 remain coaxially aligned with the mounting groove 51 throughout the bending, liquid filling, and welding processes. This avoids the assembly internal stress generated by traditional manual bending or welding in a free state, resulting in a more uniform and dense weld layer. The shear strength of the weld layer is increased from 29.5 MPa in Example 4 to 31.2 MPa.

[0101] Reduced interfacial thermal resistance: Precise positioning ensures that the gap between the outer wall of the evaporation section 61 and the inner wall of the mounting groove 51 is consistent at all positions, resulting in more uniform and full solder filling during reflow soldering. The heat pipe assembly 6 also experiences more balanced stress during rolling, avoiding excessive local deformation or insufficient adhesion caused by bias voltage. The interfacial temperature difference is reduced from 2.0℃ to 1.6℃, and the surface temperature uniformity of the substrate 5 is optimized from ±1.4℃ to ±1.0℃.

[0102] Improving the internal quality of heat pipe assembly 6: Welding and sealing are performed under the constraint of bending mechanism 2, eliminating springback stress at the bends of heat pipe assembly 6. The weld is sealed without additional tension, reducing the risk of minor leaks. Precise positioning ensures uniform stress on heat pipe assembly 6 during subsequent rolling, reducing outer diameter deformation from 0.11 mm to 0.08 mm, effectively protecting the internal sintered wicking structure. As a result, the internal vacuum level of heat pipe assembly 6 is increased from 5.8 × 10⁻³ Pa to 4.3 × 10⁻³ Pa, and the start-up time is shortened from 15 seconds to 13 seconds.

[0103] 5. Comprehensive Performance Evaluation: Among all embodiments, Embodiment 5 exhibits the best comprehensive performance. Although Embodiment 4 achieved better heat transfer by optimizing the liquid filling amount, Embodiment 5, with the support of the bending mechanism 2, achieved precise control throughout the entire process of "positioning—bending—liquid filling—welding—rolling." It outperformed Embodiment 4 in all key indicators, including thermal resistance, heat dissipation power, interface temperature difference, temperature uniformity, welding strength, deformation, and vacuum degree, verifying the crucial role of the bending mechanism 2 positioning scheme in improving the comprehensive performance of the rolled heat pipe direct-contact radiator. Furthermore, this scheme demonstrates good consistency and is more suitable for automated mass production scenarios. The outer diameter deformation of the heat pipe assembly 6 after rolling in all embodiments was controlled within the range of 0.08~0.19mm, and no damage to the heat pipe assembly 6 was observed. This indicates that the multiple rolling strategy with a 0.05mm reduction each time has good process safety, improving product quality and heat dissipation effect.

[0104] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A manufacturing process for a direct-contact heat sink with a rolled heat pipe, characterized in that: Includes the following steps: Substrate (5) fabrication: Several parallel mounting grooves (51) are formed on the upper surface of the substrate (5), and the mounting grooves (51) match the outer contour of the heat pipe assembly (6). Heat pipe assembly (6) fabrication: It consists of several copper gravity heat pipes with a copper-based liquid wick sintered inside, and includes multiple evaporation sections (61) and condensation sections (62). The multiple evaporation sections (61) are matched with the mounting groove (51). After vacuuming, a specified weight of ultrapure water is injected and sealed to form a gravity heat pipe. The weight of ultrapure water is calculated according to the liquid injection formula. Assembly and welding: The evaporation section (61) is welded to the mounting groove (51), and the heat pipe assembly (6) is rolled flat by a roller press; Fin assembly (7): Select aluminum plates of specified thickness to stamp fins (7), and fix them to the condensation section (62) by brazing.

2. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 1, characterized in that: The assembly and welding steps include: Rolling: The evaporation section (61) is embedded into the mounting groove (51), and the substrate (5) is placed on the tooling fixture for clamping and positioning. The roller press rolls the evaporation section (61) flat. Welding: Weld the heat pipe assembly (6) after rolling to form a weld layer between the evaporation section (61) and the mounting groove (51).

3. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 1, characterized in that: The assembly and welding steps include: Welding: The evaporation section (61) is embedded into the mounting groove (51), and the substrate (5) is placed on the welding fixture. Reflow soldering is used to weld the substrate, so that a welding layer is formed between the evaporation section (61) and the mounting groove (51). Rolling: The substrate (5) is then placed on the rolling fixture, and the product temperature is maintained at 40-50°C. The rolling press rolls the evaporation section (61) flat.

4. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 3, characterized in that: The substrate (5) is prepared by selecting AL6061 aluminum block and machining 8 parallel mounting grooves (51) by CNC milling. The mounting grooves (51) have a radius of 2.55 mm, a groove depth of 9.75 mm, and a length of 118 mm. The aluminum base plate is plated with chemical nickel with a film thickness of 1.2 μm.

5. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 3, characterized in that: The weight of ultrapure water is W1, and the injection volume formula is: W1=(L-L0)×S×P×ρ×K; In the formula: L is the total length of the heat pipe assembly (6); L0 is the total length of the sealing sections at both ends of the heat pipe assembly (6); L-L0 is the effective working length of the heat pipe assembly (6); S is the annular cross-sectional area of ​​the sintered copper-based wicking core, which is obtained by subtracting the cross-sectional area of ​​the vapor chamber from the cross-sectional area of ​​the inner hole of the heat pipe assembly (6); P is the porosity of the wicking core, which is 55%; ρ is the density of ultrapure water; K is the safety margin coefficient, which is 1.05~1.

1.

6. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 5, characterized in that: The weight of ultrapure water that needs to be added after vacuuming is W2 = W1 + W1 * 20%.

7. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 3, characterized in that: The heat pipe assembly (6) is formed by bending mechanism (2). The substrate (5) is mounted on bending mechanism (2) for positioning. The bending mechanism (2) bends the heat pipe assembly (6) to form an evaporation section (61) embedded with multiple mounting grooves (51) and a condensation section (62) connected to the evaporation section (61). The bending mechanism (2) presses against the evaporation section (61) for positioning. Then, after vacuuming, ultrapure water is filled in. Finally, welding and rolling are performed.

8. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 7, characterized in that: The bending mechanism (2) includes: A bending seat (21) is provided on the body (1) and has a snap-fit ​​groove (23) that engages with the evaporation section (61). A positioning plate (22) is set on the body (1), and the heat pipe assembly (6) is positioned against the positioning plate (22) and the mounting groove (51); The pressing component (3) is installed on the body (1) and presses vertically downward against the heat pipe assembly (6) for positioning; The bending head pushes the heat pipe assembly (6) to bend and form the condensation section (62).

9. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 8, characterized in that: The pressure-absorbing component (3) includes: The pressure seat (31) is slidably mounted on the body (1) in the direction close to or away from the substrate (5), and has multiple pressure grooves (33) that match the heat pipe assembly (6). The pressure member (32) is used to drive the pressure seat (31) to move.

10. The manufacturing process of a direct-contact heat sink with a rolled heat pipe according to claim 8, characterized in that: The bending seat (21) is slidably installed on the machine body (1), the roller press is installed on the machine body (1), and the bending seat (21) moves the drive plate (5) to the pressing assembly (3) or the roller press.

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