Microchannel heat sink with microtextured surface and method of manufacture

Abstract

The application provides a micro-channel radiator with a micro-textured surface and a preparation method thereof, and relates to the technical field of high heat flow density electronic device heat dissipation. The application discloses a micro-channel radiator with a micro-textured surface and a preparation method thereof, and relates to the technical field of high heat flow density electronic device heat dissipation.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology for high heat flux density electronic devices, and more specifically, to an ultra-large aspect ratio microchannel heat sink with a microtextured surface and its preparation method. Background Technology

[0002] Microchannel heat sinks are a novel type of heat sink that rapidly removes heat from electronic devices by having a flowing liquid working medium contact the walls of microchannels. They offer advantages such as small size and large heat dissipation surface area, making them ideal components for solving the heat dissipation challenges of high heat flux density electronic devices. Research shows that ultra-large aspect ratio microchannel heat sinks with an aspect ratio greater than 15 exhibit excellent heat dissipation performance, with critical heat flux densities exceeding 1000 W / cm². 2 Fabricating microtextures on the surface of microchannels and controlling heat transfer area, wetting properties, and bubble nucleation density can further improve the heat dissipation performance of microchannel radiators. However, ultra-high aspect ratio microchannel radiators are typical narrow-slit, thin-walled, and weak-stiffness structures that are difficult to process. Achieving deformation-free and heat-damage-free processing of their geometry and fabricating microtextures on the surface of ultra-high aspect ratio microchannels are quite challenging.

[0003] Deep reactive ion etching (DRIE), electrochemical deposition, and additive manufacturing are all methods capable of fabricating ultra-large aspect ratio microchannel heat sinks, but they all suffer from bottlenecks such as low processing efficiency and high cost. Wire electrical discharge machining (EDM) can also fabricate ultra-large aspect ratio microchannel heat sinks, but this method involves single-wire cutting, resulting in low efficiency and thermal damage and significant surface thermal resistance. None of the above methods can create surface microtextures while fabricating ultra-large aspect ratio microchannels, requiring additional post-processing steps.

[0004] Japanese Patent JP2005032749A discloses a method and apparatus for manufacturing heat sinks, using an abrasive wire saw to cut and process slit heat sinks of different shapes. US Patent US6390181B1 discloses a densely finned tungsten carbide and polycrystalline diamond cooling module, indicating that the densely finned tungsten carbide heat sink can be processed using a wire saw, and further mentions that the roughened surface after wire sawing can increase the contact area, thereby improving heat dissipation. Abrasive wire sawing has significant advantages in improving processing efficiency for processing ultra-large aspect ratio microchannel heat sinks; however, existing technologies mainly focus on achieving conventional surface roughening through wire sawing, failing to fully recognize the important influence of surface wettability on heat dissipation. Furthermore, different application scenarios have different requirements for the heat dissipation performance of microchannel heat sinks. However, existing technologies have failed to precisely design and control the microtexture of the wire-saw-processed surface for specific application scenarios, resulting in significant differences in the performance of existing microchannel heat sinks in diverse application environments, failing to fully realize their heat dissipation potential. Due to a lack of precise design of surface microstructures, microchannel heat sinks machined by abrasive wire saws exhibit significant performance variations. This makes it difficult to guarantee product consistency and stability in actual production and application, increasing the difficulty and cost of quality control. Therefore, when using abrasive wire saws to machine ultra-large aspect ratio microchannel heat sinks, how to achieve precise construction and controllable machining of the surface microtexture has become a critical problem that urgently needs to be solved. Summary of the Invention

[0005] This invention discloses a microchannel heat sink with a microtextured surface, which aims to improve the problems mentioned above.

[0006] The present invention adopts the following solution:

[0007] A microchannel heat sink with a microtextured surface includes a liquid flow cavity and an upper cover plate that adheres to the liquid flow cavity; a liquid inlet and an outlet are provided on both sides of the upper cover plate or the liquid flow cavity; it also includes a microchannel substrate placed inside the liquid flow cavity; a plurality of parallel-spaced microchannels are formed on the microchannel substrate; the walls of the microchannels are arranged with periodic microtextures; the structural parameters of the periodic microtextures can be precisely designed and processed according to the requirements of the application; when the application is single-phase forced convection heat transfer of liquid, the surface periodic microtexture is designed as a hydrophilic structure conforming to the Wenzel model to increase the wettability ratio of the fluid to the solid, thereby increasing the heat dissipation area of ​​the microchannel; when the application is two-phase flow boiling heat transfer of liquid, the surface periodic microtexture is designed as a hydrophobic structure conforming to the Cassie-Baxter model to reduce flow resistance, promote bubble generation and detachment, and enhance the boiling heat transfer coefficient;

[0008] Furthermore, the surface profile of the periodic microtexture is a triangular wave.

[0009] Furthermore, the microchannel has one or more combinations of rectangular, circular, trapezoidal, and wavy microstructures on its cross-section perpendicular to the fluid direction.

[0010] Furthermore, each group of microchannels has several microstructures arranged along the height direction of the microchannel substrate.

[0011] Furthermore, the microchannel substrate includes a plurality of micropillars arranged in a parallel, spaced array, with adjacent micropillars forming the microchannel, and the cross-section of the micropillars in the direction parallel to the bottom surface of the microchannel substrate is rhomboid.

[0012] Furthermore, the ratio of the depth to the width of the microchannel is called the aspect ratio, which is greater than 15.

[0013] The present invention also provides a method for preparing the microchannel heat sink with the microtextured surface described above, which specifically includes the following steps:

[0014] S1: Design the geometry and surface microtexture parameters of the microchannel according to the application scenario, select the type of bonded abrasive wire saw and the dry / wet processing method according to the microchannel substrate material, select the specifications of the abrasive wire saw and wire roller according to the microchannel structure parameters, and design the processing trajectory according to the microchannel structure.

[0015] S2: Mount the workpiece onto the worktable of the bonded abrasive wire saw multi-wire cutting machine.

[0016] S3: Import the workpiece's machining trajectory parameters into the bonded abrasive wire saw cutting machine, and set the linear tension and linear speed. v s Workpiece feed rate v f and the reciprocating cycle of the wire saw T r Based on the material properties of the workpiece, find the relationship between the microstructure peak-valley value PV, wavelength λ, and processing parameters: PV = k 1· v f a · v s b · T r c , λ= k 2· v f m · v s n · T rf ;in, k 1. a , b , c These are empirical parameters related to the material. k 2. m , f Approximately equal to 1, n Approximately equal to 0, and thus the processing parameters can be calculated in reverse;

[0017] S4: Use the control panel to lower the bottom surface of the workpiece to the position where it will contact the bonded abrasive wire saw wire mesh;

[0018] S5: Running the processing program: The bonded abrasive wire saw mesh moves in a periodic reciprocating motion under the drive of the machine tool drive system. The workpiece begins to feed, the wire saw mesh contacts the workpiece and begins to remove material. During the reciprocating motion of the wire saw mesh, the wire saw forms a regular microstructure through lateral movement.

[0019] S6: After the processing program is completed, the workpiece is removed, cleaned, and dried to obtain the final microchannel substrate;

[0020] S7: The microchannel substrate, top cover plate, and liquid flow cavity are encapsulated to obtain the final ultra-large aspect ratio microchannel heat sink with a microtextured surface.

[0021] Furthermore, when the microchannel substrate material is a non-metallic material with high hardness, the abrasive wire saw in step S1 is an active abrasive wire saw, the dry-wet processing method is dry processing, and the active abrasive can catalyze the phase change of the substrate material under the action of pressure and temperature, reducing the processing difficulty.

[0022] Furthermore, when several parallel-spaced micropillars are processed on the microchannel substrate, and the cross-section of the micropillars in the direction parallel to the bottom surface of the microchannel substrate is rhomboid, in step S5, the processing is divided into two angled vertical feed cuts, so as to... l 1 and l 2. Distinguish between steps ① and ②: First, install the microchannel substrate directly above the center of the wire saw mesh, with its front side parallel to the side of the wire roller; then rotate the worktable by an angle σ to begin... l The corresponding processing step 1; when the preset processing depth is reached, the wire saw wire mesh stops moving, and the worktable rises back to the origin, thus completing step 1; then the worktable proceeds with... l Rotate by θ angle with 1 as the reference to begin l 2. The corresponding processing; once the preset processing depth is reached, the processing of step ② is completed, and the processing of the rhomboid column array microchannel structure is finally realized.

[0023] Beneficial effects:

[0024] This design features an ultra-large aspect ratio microchannel radiator with a microtextured surface. The structural parameters of the microtexture can be precisely designed and manufactured according to the requirements of the application. By setting the periodic microtexture on the microchannel wall, the heat dissipation performance of the microchannel can be controlled. When the ultra-large aspect ratio microchannel radiator is used for single-phase forced convection heat transfer of liquid, the periodic microtexture on the surface is designed as a hydrophilic structure conforming to the Wenzel model, which can increase the wettability ratio between the fluid and the solid, thereby increasing the heat dissipation area of ​​the microchannel. When the ultra-large aspect ratio microchannel radiator is used for two-phase boiling heat transfer of liquid, the periodic microtexture on the surface can be designed as a hydrophobic structure conforming to the Cassie-Baxter model to reduce flow resistance, promote bubble generation and detachment, and enhance the boiling heat transfer coefficient. A one-step fabrication method using bonded abrasive wire saw reciprocating multi-wire cutting can achieve one-step forming of microchannels with ultra-high aspect ratios and surface microtextures. Surface microstructure processing requires no additional post-processing steps. The diameter of the bonded abrasive wire saw, the cutting tool, can be as small as 50 micrometers, making it a flexible process that easily achieves ultra-high aspect ratio narrow slit structures while minimizing deformation of thin-walled structures. The bonded abrasive wire saw cutting temperature is low, resulting in no thermal damage and preventing degradation of the microchannel walls that could reduce the material's thermal conductivity. This method can process both metals and non-metals, making it applicable to a wide range of materials. It can process all ultra-high aspect ratio microchannels in the same direction in a single pass, is simple, requires minimal equipment, is low-cost, highly efficient, and easy for large-scale mass production. The process generates no waste liquid pollution, making it environmentally friendly and energy-efficient. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an ultra-large aspect ratio microchannel heat sink with a microtextured surface in Example 1;

[0026] Figure 2 This is a schematic diagram of the ultra-large aspect ratio microchannel substrate structure with a microtextured surface in Example 1;

[0027] Figure 3 This is a schematic cross-sectional view of the ultra-high aspect ratio microchannel substrate structure with a microtextured surface in Example 1;

[0028] Figure 4 The figures are schematic diagrams of diamond wire saw multi-wire cutting processes using microchannel structures with ultra-large aspect ratios and microtextured surfaces, as described in Examples 1 to 7. v fy , v fz For different axial feed rates, v s Indicates linear velocity;

[0029] Figure 5This is the microchannel substrate actually processed by diamond wire saw multi-wire cutting in Example 2;

[0030] Figure 6 This is a schematic diagram of the 3D morphology and 2D contour of the microstructure of the microchannel substrate channel wall traces actually processed in Example 2;

[0031] Figure 7 This is a schematic diagram of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 3;

[0032] Figure 8 This is a schematic cross-sectional view of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 3;

[0033] Figure 9 This is a schematic diagram of the processing trajectory of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 3;

[0034] Figure 10 This is a schematic diagram of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 4;

[0035] Figure 11 This is a schematic cross-sectional view of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 4;

[0036] Figure 12 This is a schematic diagram of the processing trajectory of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 4;

[0037] Figure 13 This is a schematic diagram of the ultra-high aspect ratio microchannel structure with a microtextured surface in Example 5;

[0038] Figure 14 This is a schematic cross-sectional view of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 5;

[0039] Figure 15 This is a schematic diagram of the processing trajectory of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 5;

[0040] Figure 16 This is a schematic diagram of the ultra-high aspect ratio microchannel structure with a microtextured surface in Example 6;

[0041] Figure 17 This is a schematic cross-sectional view of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 6;

[0042] Figure 18 This is a schematic diagram of the processing trajectory of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 6;

[0043] Figure 19 This is a schematic diagram of the ultra-high aspect ratio microchannel structure with a microtextured surface in Example 7;

[0044] Figure 20 This is a schematic cross-sectional view of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 7;

[0045] Figure 21 This is a schematic diagram of the processing trajectory of the ultra-large aspect ratio microchannel structure with a microtextured surface in Example 7;

[0046] Figure 22 This is a schematic diagram of a hard abrasive wire saw with a coating of active pure metal used in Example 8 for multi-wire cutting.

[0047] Figure reference numerals: 1. Top cover plate; 2. Coolant inlet; 3. Coolant outlet; 4. Ultra-large aspect ratio microchannel substrate; 5. Liquid flow chamber; 6. Workpiece; 7. Wire roller; 8. Diamond wire saw wire mesh; 9. Fixing plate; 10. Worktable; 11. Hard abrasive; 12. Metal coating; 13. Coated hard abrasive; 14. Core wire; 15. Metal binder. Detailed Implementation

[0048] Example 1

[0049] like Figure 1 and Figure 2 As shown, this embodiment provides an ultra-large aspect ratio microchannel heat sink with a microtextured surface, comprising an upper cover plate 1, a coolant inlet 2, a coolant outlet 3, an ultra-large aspect ratio microchannel substrate 4, and a liquid flow chamber 5. The microchannel substrate 4 has a plurality of parallel spaced microchannels arranged in an array, and the walls of the microchannels are arranged with microstructures to regulate the heat dissipation performance of the microchannels. The coolant of the microchannel heat sink enters the liquid flow chamber 5 through the coolant inlet 2 on the upper cover plate 1 at a certain flow rate, flows through the microchannel substrate 4, and then flows out from the coolant outlet 3.

[0050] In this embodiment, parallel-spaced microchannels are arranged on the microchannel substrate 4, and the microchannels are suitable for the passage of coolant fluid. The walls of the microchannels are arranged with periodic microtextures; the surface profile of the periodic microtextures is triangular wave; the structural parameters of the periodic microtextures can be precisely designed and processed according to the requirements of the application; when the application is single-phase forced convection heat transfer of liquid, the surface periodic microtextures are designed as hydrophilic structures conforming to the Wenzel model to increase the wettability ratio between the fluid and the solid, thereby increasing the heat dissipation area of ​​the microchannel; when the application is two-phase flow boiling heat transfer of liquid, the surface periodic microtextures are designed as hydrophobic structures conforming to the Cassie-Baxter model to reduce flow resistance, promote bubble generation and detachment, and enhance the boiling heat transfer coefficient; one or more combinations of rectangular, circular, trapezoidal, and wavy microstructures are arranged on the cross-section of the microchannel perpendicular to the fluid direction, and each group of microchannels has several microstructures arranged along the height direction of the microchannel substrate. By configuring the aforementioned microstructure, the fluid turbulence effect can be enhanced, flow resistance reduced, the heat transfer area increased, the boundary layer disrupted, and the critical heat flux density increased, thereby improving the heat dissipation performance of the microchannel. The ratio of the depth to the width of the microchannel is called the aspect ratio, which is greater than 15.

[0051] In this embodiment, the hydrophilic structure of the Wenzel model refers to a structure in which the liquid can completely fill the microtextured surface, while the hydrophobic structure of the Cassie-Baxter model refers to a structure in which the liquid and gas co-occupy the microtextured surface (composite interface). The formulas for both models are existing technologies and will not be elaborated here.

[0052] Preferably, a plurality of parallel-spaced micropillars are formed on the microchannel substrate 4, with microchannels formed between adjacent micropillars, and the cross-section of each micropillar is rhomboid in the direction parallel to the bottom surface of the microchannel substrate. The micropillars can optimize fluid flow characteristics and heat transfer characteristics.

[0053] Example 2

[0054] Microchannel heat sink substrate structure such as Figure 2 and Figure 3 As shown, the microchannel substrate material is a copper block, with specific dimensions L=D=30mm and H=10mm as an example; the microchannel structure dimensions are set as h=8000μm, a=270μm, b=750μm, and the microchannel aspect ratio is 29.6. The microchannel heat sink is used for liquid two-phase flow boiling heat transfer, and its surface microtexture is designed as a hydrophobic structure with surface microtexture dimensions PV=4μm and λ=0.21mm.

[0055] Combination Figure 4The one-step fabrication method for the above-mentioned ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0056] S1: Based on the structure of the microchannel substrate 4, an electroplated diamond wire saw with a wire diameter of 250μm and a wire roller 7 with a groove spacing of 750μm are selected to form a diamond wire saw wire mesh 8, and the corresponding processing trajectory is a straight line in the Z-axis direction.

[0057] S2: AB glue is used as an adhesive to bond the workpiece 6 to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine. In this embodiment, the workpiece 6 refers to the microchannel substrate to be processed.

[0058] S3: Import the machining trajectory parameters of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the Z-axis feed trajectory uses linear velocity. v s =25m / s, workpiece feed speed v fz =0.15mm / min and the reciprocating cycle of the wire saw T r =85s; linear velocity is used at the bottom of the microchannel. v s =25m / s, workpiece feed speed v fz =0.0001mm / min, reciprocating cycle of the wire saw T r =100s, keeping the workpiece in a state of almost no feed for 10 minutes, eliminating the feed lag caused by the bow wire, thereby achieving the theoretically designed feed distance and ensuring machining accuracy;

[0059] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0060] S5: Running the processing program: The diamond wire saw mesh 8 is driven by the machine tool drive system to perform periodic reciprocating motion. The workpiece 6 starts to feed according to the imported processing trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scratch and remove the material. During the reciprocating motion, the diamond wire saw mesh will move laterally according to the set trajectory route, thereby forming a regular microstructure.

[0061] S6: After the processing program is completed, remove the adhesive to take out workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in a 50℃ oven for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate, such as... Figure 5As shown.

[0062] S7: Embed the ultra-large aspect ratio microchannel substrate 4 into the liquid flow cavity 5, making the two fit together. Place the top cover plate 1 on top, and achieve a sealed encapsulation of the three by brazing. Connect water pipes to the liquid inlet 2 and outlet 3 of the top cover plate 1, and connect them to a water pump to form a liquid convection circulation loop, ultimately obtaining a complete ultra-large aspect ratio microchannel heat sink with a microtextured surface.

[0063] like Figure 6 As shown; the microtexture obtained by the process parameters in this embodiment is a triangular wave shape. After actual measurement by the 3D optical profilometer Zygo, the average value of its characteristic parameters is obtained: PV=3.84μm, λ=0.16mm.

[0064] In this embodiment, the electroplated diamond wire saw refers to a wire saw with diamond abrasive grains fixed to the cutting core wire by electroplating. Under the same structural conditions of ultra-large aspect ratio microchannel substrate, the diamond wire saw reciprocating multi-wire cutting method used in this embodiment takes approximately 63 minutes, while industrial EDM takes approximately 223 minutes. The diamond wire saw multi-wire cutting efficiency is more than 70% higher than that of EDM. In the liquid two-phase flow boiling heat transfer test, the ultra-large aspect ratio microchannel heat sink processed by diamond wire saw multi-wire cutting can withstand a higher heat flux density than the sample processed by EDM, allowing the test wall surface to maintain a better temperature, and improving heat dissipation performance by more than 50%.

[0065] Example 3

[0066] The ultra-large aspect ratio rectangular recessed microchannel heat sink substrate structure with microtextured surface described in this embodiment is as follows: Figures 7 to 8 As shown, the heat sink substrate is made of copper block, and the specific dimensions of the microchannel substrate are L=D=10.4mm and H=6mm; the microchannel structure dimensions are h=5000μm, a=100μm, b=700μm, c1=c2=1000μm, e=f=500μm, and the microchannel aspect ratio is 50. The microchannel heat sink is used for liquid two-phase flow boiling heat transfer. Its surface microtexture is designed as a hydrophobic structure, with surface microtexture dimensions PV=4μm and λ=0.21mm. Combined with... Figure 4 , Figure 7 and Figure 8 The one-step fabrication method for the ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0067] S1: Based on the microchannel substrate structure, an electroplated diamond wire saw with a wire diameter of 80μm and a wire roller 7 with a groove spacing of 700μm are selected to form a diamond wire saw wire mesh 8. The corresponding processing trajectory is designed, such as... Figure 9;

[0068] S2: AB glue is used as an adhesive to bond the workpiece to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove of the worktable 10. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine.

[0069] S3: Import the machining trajectory file of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the Z-axis feed trajectory uses linear velocity. v s =25m / s, workpiece feed speed v fz =0.15mm / min and the reciprocating cycle of the wire saw T r =85s; linear velocity is used at the corner junction of the indented structure. v s =25m / s, workpiece feed speed v fz =0.0001mm / min, reciprocating cycle of the wire saw T r =85s, keeping the workpiece in a state of almost no feed for 10 minutes to eliminate the feed lag caused by the bow, thereby achieving the theoretically designed feed distance and ensuring machining accuracy; the Y-axis feed trajectory adopts linear velocity v s =25m / s, workpiece feed speed v fy =0.15mm / min, reciprocating cycle of the wire saw T r =85s;

[0070] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0071] S5: Running the machining program: The diamond wire saw mesh 8 is driven by the machine tool drive system to perform periodic reciprocating motion. The workpiece 6 starts to feed according to the imported machining trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scratch and remove the material. During the reciprocating motion, the diamond wire saw mesh will move laterally and thus form a regular microstructure.

[0072] S6: After the processing program is completed, remove the adhesive to take out the workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in an oven at 50°C for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate.

[0073] S7: The ultra-large aspect ratio microchannel substrate 4 is embedded into the liquid flow chamber 5, ensuring a close fit. A top cover plate 1 is placed on top, and the three components are sealed by brazing. Water pipes are connected to the liquid inlet 2 and outlet 3 of the top cover plate 1, which are then connected to a water pump to form a liquid convection circulation loop, ultimately resulting in a complete ultra-large aspect ratio microchannel radiator with a microtextured surface. In liquid two-phase boiling flow heat transfer tests, the ultra-large aspect ratio sidewall rectangular recessed microchannel radiator processed by diamond wire saw multi-wire cutting showed a 25-35% increase in Nusselt number and an 8-12% reduction in overall pressure drop compared to a microchannel radiator without recesses.

[0074] Example 4

[0075] The micro-textured surface and the ultra-large aspect ratio circular recessed microchannel heat sink substrate structure with sidewalls in this embodiment are as follows: Figures 10 to 11 As shown, the heat sink substrate material is a copper block with specific dimensions L=D=10.4mm and H=6mm; the microchannel structure dimensions are h=5000μm, a=100μm, b=700μm, c1=c2=1000μm, d=Φ500μm, and the microchannel aspect ratio is 50. The microchannel heat sink is used for liquid two-phase flow boiling heat transfer. Its surface microtexture is designed as a hydrophobic structure with surface microtexture dimensions PV=2.1μm and λ=0.25mm. The one-step forming method for the ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0076] S1: Based on the microchannel substrate structure, an electroplated diamond wire saw with a wire diameter of 80μm and a wire roller 7 with a groove spacing of 700μm are selected to form a diamond wire saw wire mesh 8. The corresponding processing trajectory is designed, such as... Figure 12 ;

[0077] S2: AB glue is used as an adhesive to bond the workpiece to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove of the worktable 10. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine.

[0078] S3: Import the machining trajectory file of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the Z-axis feed trajectory uses linear velocity. v s =15m / s, workpiece feed speed v fz =0.15mm / min, reciprocating cycle of the wire saw T r =100s; linear velocity is used at the corner junction of the indented structure. v s =15m / s, workpiece feed speed v fz=0.0001mm / min, reciprocating cycle of the wire saw T r =100s, keeping the workpiece in a state of almost no feed for 10 minutes to eliminate the feed lag caused by the bow, thereby achieving the theoretically designed feed distance and ensuring machining accuracy; the curved feed trajectory uses linear velocity v s =15m / s, workpiece feed speed v fy = v fz =0.15mm / min, reciprocating cycle of the wire saw T r =100s;

[0079] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0080] S5: Running the machining program: The diamond wire saw mesh 8 is driven by the machine tool drive system to perform periodic reciprocating motion. The workpiece 6 starts to feed according to the imported machining trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scratch and remove the material. During the reciprocating motion, the diamond wire saw mesh will move laterally and thus form a regular microstructure.

[0081] S6: After the processing program is completed, remove the adhesive to take out the workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in an oven at 50°C for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate.

[0082] S7: The ultra-large aspect ratio microchannel substrate 4 is embedded into the liquid flow cavity 5, ensuring a close fit. A top cover plate 1 is placed on top, and the three components are sealed by brazing. Water pipes are connected to the liquid inlet 2 and outlet 3 of the top cover plate 1, connecting to a water pump to form a liquid convection circulation loop, ultimately obtaining a complete ultra-large aspect ratio microchannel radiator with a microtextured surface. In liquid two-phase flow boiling heat transfer tests, the ultra-large aspect ratio sidewall circular recessed microchannel radiator processed by diamond wire saw multi-wire cutting shows a 20-30% increase in Nusselt number and a 5-8% reduction in overall pressure drop compared to a microchannel radiator without recesses.

[0083] Example 5

[0084] The microchannel heat sink substrate structure with ultra-large aspect ratio sidewall sinusoidal recessed microchannel and microtextured surface described in this embodiment is as follows: Figures 13 to 14As shown, the heat sink substrate material is a copper block with specific dimensions L=D=10.4mm and H=6mm; the microchannel structure dimensions are h=5000μm, a=100μm, b=700μm, c=1000μm, and A=130μm, with a microchannel aspect ratio of 50. The microchannel heat sink is used for liquid two-phase flow boiling heat transfer. Its surface microtexture is designed as a hydrophobic structure with surface microtexture dimensions PV=2.4μm and λ=0.15mm. The one-step forming method for the ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0085] S1: Based on the microchannel substrate structure, an electroplated diamond wire saw with a wire diameter of 80μm and a wire roller 7 with a groove spacing of 700μm are selected to form a diamond wire saw wire mesh 8. The corresponding processing trajectory is designed, such as... Figure 15 ;

[0086] S2: AB glue is used as an adhesive to bond the workpiece to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove of the worktable 10. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine.

[0087] S3: Import the machining trajectory file of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the curved feed trajectory uses linear velocity. v s =25m / s, workpiece feed speed v fy = v fz =0.05mm / min, reciprocating cycle of the wire saw T r =180s; linear velocity is used at the corner junction of the indented structure. v s =25m / s, workpiece feed speed v fz =0.0001mm / min, reciprocating cycle of the wire saw T r =180s, keeping the workpiece in a state of almost no feed for 10 minutes, eliminating the feed lag caused by the bow wire, thereby achieving the theoretically designed feed distance and ensuring machining accuracy;

[0088] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0089] S5: Running the machining program: The diamond wire saw mesh 8 is driven by the machine tool drive system to perform periodic reciprocating motion. The workpiece 6 starts to feed according to the imported machining trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scratch and remove the material. During the reciprocating motion, the diamond wire saw mesh will move laterally and thus form a regular microstructure.

[0090] S6: After the processing program is completed, remove the adhesive to take out the workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in an oven at 50°C for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate.

[0091] S7: The ultra-large aspect ratio microchannel substrate 4 is embedded into the liquid flow cavity 5, ensuring a tight fit. A top cover plate 1 is placed on top, and the three components are sealed by brazing. Water pipes are connected to the liquid inlet 2 and outlet 3 of the top cover plate 1, which are then connected to a water pump to form a liquid convection circulation loop, ultimately resulting in a complete ultra-large aspect ratio microchannel radiator with a microtextured surface. In liquid two-phase flow boiling heat transfer tests, the ultra-large aspect ratio sidewall sinusoidal recessed microchannel radiator, machined by diamond wire saw multi-wire cutting, shows a 30-45% increase in Nusselt number and a 10-15% reduction in overall pressure drop compared to a microchannel radiator without recesses.

[0092] Example 6

[0093] The ultra-high aspect ratio bottom circular recessed microchannel heat sink substrate structure with a microtextured surface described in this embodiment is as follows: Figures 16 to 17 As shown, the heat sink substrate material is a copper block with specific dimensions L=D=10.4mm and H=6mm; the microchannel structure dimensions are h=5000μm, a=100μm, b=700μm, d=Φ500μm, and the microchannel aspect ratio is 50. The microchannel heat sink is used for liquid two-phase flow boiling heat transfer. Its surface microtexture is designed as a hydrophobic structure with surface microtexture dimensions PV=2.4μm and λ=0.8mm. The one-step forming method for the ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0094] S1: Based on the microchannel substrate structure, an electroplated diamond wire saw with a wire diameter of 80μm and a wire roller 7 with a groove spacing of 700μm are selected to form a diamond wire saw wire mesh 8. The corresponding processing trajectory is designed, such as... Figure 18 ;

[0095] S2: AB glue is used as an adhesive to bond the workpiece to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove of the worktable 10. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine.

[0096] S3: Import the machining trajectory file of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the Z-axis feed trajectory uses linear velocity. v s =25m / s, workpiece feed speed v fz =0.4mm / min, reciprocating cycle of the wire saw T r =120s; linear velocity is used at the corner junction of the indented structure. v s =25m / s, workpiece feed speed v fz =0.0001mm / min, reciprocating cycle of the wire saw T r =100s, keeping the workpiece in a state of almost no feed for 10 minutes to eliminate the feed lag caused by the bow, thereby achieving the theoretically designed feed distance and ensuring machining accuracy; the curved feed trajectory uses linear velocity v s =25m / s, workpiece feed speed v fy = v fz =0.03mm / min, reciprocating cycle of the wire saw T r =120s;

[0097] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0098] S5: Running the machining program: The diamond wire saw mesh 8 is driven by the machine tool drive system to perform periodic reciprocating motion. The workpiece 6 starts to feed according to the imported machining trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scratch and remove the material. During the reciprocating motion, the diamond wire saw mesh will move laterally and thus form a regular microstructure.

[0099] S6: After the processing program is completed, remove the adhesive to take out the workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in an oven at 50°C for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate.

[0100] S7: The ultra-large aspect ratio microchannel substrate 4 is embedded into the liquid flow chamber 5, ensuring a close fit. A top cover plate 1 is placed on top, and the three components are sealed by brazing. Water pipes are connected to the liquid inlet 2 and outlet 3 of the top cover plate 1, connecting to a water pump to form a liquid convection circulation loop, ultimately obtaining a complete ultra-large aspect ratio microchannel radiator with a microtextured surface. In liquid two-phase flow boiling heat transfer tests, the ultra-large aspect ratio bottom circular recessed microchannel radiator processed by diamond wire saw multi-wire cutting shows a 30-40% increase in Nusselt number and a 13-19% reduction in overall pressure drop compared to a microchannel radiator without a recess.

[0101] Example 7

[0102] The ultra-large aspect ratio rhombic micropillar array microchannel heat sink substrate structure with microtextured surface described in this embodiment is as follows: Figures 19 to 20 As shown, the heat sink substrate is a block of copper with specific dimensions L=D=10.4mm and H=6mm; the microchannel structure dimensions are h=5000μm, a=100μm, and b=700μm. σ =90°, θ =90°, microchannel aspect ratio is 50, the microchannel heat sink is used for liquid two-phase flow boiling heat transfer, its surface microtexture is designed as a hydrophobic structure, the surface microtexture size PV=1.7μm, λ=0.6mm. The one-step forming method of the ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0103] S1: Based on the microchannel substrate structure, an electroplated diamond wire saw with a wire diameter of 80μm and a wire roller 7 with a groove spacing of 700μm are selected to form a diamond wire saw wire mesh 8. The corresponding processing trajectory is designed, such as... Figure 21 ;

[0104] S2: AB glue is used as an adhesive to bond the workpiece to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove of the worktable 10. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine.

[0105] S3: Import the machining trajectory file of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the Z-axis feed trajectory uses linear velocity. v s =5m / s, workpiece feed speed v fz =0.2mm / min, reciprocating cycle of the wire saw T r =150s; linear velocity is used at the bottom of the microchannel. v s =25m / s, workpiece feed speed vfz =0.0001mm / min, reciprocating cycle of the wire saw T r =150s, keeping the workpiece in a state of almost no feed for 10 minutes, eliminating the feed lag caused by the bow wire, thereby achieving the theoretically designed feed distance and ensuring machining accuracy;

[0106] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0107] S5: Running the machining program: The diamond wire saw mesh 8, driven by the machine tool drive system, performs periodic reciprocating motion. The workpiece 6 begins to feed according to the imported machining trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scrape and remove material. During the reciprocating motion, the wire saw mesh will move laterally, thus forming regular microstructures. Specifically, the machining is divided into two angled vertical feed cuts, as shown in the top view. l 1 and l 2. Distinguish between steps ① and ②: First, install the microchannel substrate 6 directly above the center of the wire saw mesh 8, with its front side parallel to the side of the wire roller; then, the worktable 10... σ By rotating the angle, it can begin. l The corresponding processing step 1; when the designed processing depth is reached, the diamond wire saw wire mesh 8 will stop moving, and the worktable will rise back to the origin, thus completing the processing in step 1; then the worktable 10 will proceed with... l 1 as the benchmark θ Rotate the angle to begin. l 2. The corresponding processing; once the designed processing depth is reached, step ② is completed, and the processing of the ultra-large aspect ratio rhombic column array microchannel structure is finally realized;

[0108] S6: After the processing program is completed, remove the adhesive to take out the workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in an oven at 50°C for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate.

[0109] S7: Embed the ultra-large aspect ratio microchannel substrate 4 into the liquid flow cavity 5, making the two fit together. Place the top cover plate 1 on top, and achieve a sealed encapsulation of the three by brazing. Connect water pipes to the liquid inlet 2 and outlet 3 of the top cover plate 1, and connect them to a water pump to form a liquid convection circulation loop, ultimately obtaining a complete ultra-large aspect ratio microchannel heat sink with a microtextured surface.

[0110] This embodiment is illustrated by... σ , θThe angle design, combined with bonded abrasive wire saws and wire rollers of different specifications, can produce rhomboid micro-pillar arrays of different angles and sizes, which can play a role in enhancing heat dissipation, such as fluid lubrication and thermal boundary disturbance.

[0111] Example 8

[0112] Microchannel heat sink substrate structure such as Figure 2 and Figure 3 As shown, the microchannel substrate material is silicon carbide. Taking a specific size of L=D=30mm and H=10mm as an example, the microchannel structure dimensions are set as h=8000μm, a=270μm, b=750μm, and the microchannel aspect ratio is 29.6. The microchannel heat sink is used for liquid two-phase flow boiling heat transfer. Its surface microtexture is designed as a hydrophobic structure with surface microtexture dimensions PV=4μm and λ=0.21mm.

[0113] Combination Figure 4 The one-step fabrication method for the above-mentioned ultra-large aspect ratio microchannel heat sink with microtextured surface includes the following steps:

[0114] S1: Dry machining is performed using a diamond abrasive wire saw coated with active chromium metal. The structure of the active abrasive wire saw is as follows: Figure 22 As shown, the metal coating 12 is chromium, and the hard abrasive 11 is diamond. During the process, the metallic chromium can catalyze the silicon carbide phase transformation and reduce the processing difficulty. According to the structure of the microchannel substrate 4, a wire roller 7 with a wire diameter of 250μm and a groove spacing of 750μm is selected to form the diamond wire saw wire mesh 8, and the corresponding processing trajectory is a straight line in the Z-axis direction.

[0115] S2: AB glue is used as an adhesive to bond the workpiece 6 to the fixing plate 9. The fixing plate 9 and the worktable 10 are fastened together through the groove. In this way, the workpiece 6 is installed on the worktable 10 of the diamond wire saw multi-wire cutting machine. In this embodiment, the workpiece 6 refers to the microchannel substrate to be processed.

[0116] S3: Import the machining trajectory parameters of workpiece 6 onto the control panel of the diamond wire saw multi-wire cutting machine, and set the process parameters: wire tension is 40N; the Z-axis feed trajectory uses linear velocity. v s =25m / s, workpiece feed speed v fz =0.15mm / min and the reciprocating cycle of the wire saw T r =85s; linear velocity is used at the bottom of the microchannel. v s =25m / s, workpiece feed speed v fz =0.0001mm / min, reciprocating cycle of the wire sawT r =100s, keeping the workpiece in a state of almost no feed for 10 minutes, eliminating the feed lag caused by the bow wire, thereby achieving the theoretically designed feed distance and ensuring machining accuracy;

[0117] S4: The control panel lowers the bottom surface of workpiece 6 to a position where it is about to contact the diamond wire saw wire mesh 8. The coordinates of this position are set to zero as the starting point of the tool coordinates to complete the tool setting.

[0118] S5: Running the processing program: The diamond wire saw mesh 8 is driven by the machine tool drive system to perform periodic reciprocating motion. The workpiece 6 starts to feed according to the imported processing trajectory. The diamond wire saw mesh 8 contacts the workpiece 6 and begins to scratch and remove the material. During the reciprocating motion, the diamond wire saw mesh will move laterally according to the set trajectory route, thereby forming a regular microstructure.

[0119] S6: After the processing program is completed, remove the adhesive to take out workpiece 6, clean it in an ultrasonic alcohol bath for 5 minutes, and dry it in a 50℃ oven for 30 minutes to obtain the final ultra-large aspect ratio microchannel substrate, such as... Figure 5 As shown.

[0120] S7: Embed the ultra-large aspect ratio microchannel substrate 4 into the liquid flow cavity 5, making the two fit together. Place the top cover plate 1 on top, and achieve a sealed encapsulation of the three by brazing. Connect water pipes to the liquid inlet 2 and outlet 3 of the top cover plate 1, and connect them to a water pump to form a liquid convection circulation loop, ultimately obtaining a complete ultra-large aspect ratio microchannel heat sink with a microtextured surface.

[0121] In Examples 2-8, the reciprocating multi-wire cutting of the bonded abrasive wire saw can achieve one-step forming of microchannel ultra-high aspect ratio structures and surface microtextures. The surface microtexture processing does not require additional post-processing steps. The diameter of the bonded abrasive wire saw cutting tool can be as small as less than 50 micrometers, which is a flexible processing method. It is easy to realize the processing of ultra-high aspect ratio narrow slit structures and thin-walled structures are not easily deformed. The cutting temperature of the bonded abrasive wire saw is low, and there is no thermal damage during processing. It will not cause the microchannel wall to deteriorate and reduce the thermal conductivity of the material.

[0122] It should be understood that the above are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

[0123] The accompanying drawings used in the above description of the embodiments only illustrate certain embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

Claims

1. A microchannel heat sink having a micro-textured surface, comprising a liquid flow cavity and an upper cover plate in contact with the liquid flow cavity, a liquid inlet and outlet are provided on both sides of the upper cover plate or the liquid flow cavity; characterized in that, Further comprising a microchannel substrate placed in the liquid flow cavity, a plurality of microchannels arranged in parallel and spaced array are formed on the microchannel substrate; the wall surface of the microchannel is arranged with periodic microtexture; the structural parameters of the periodic microtexture are accurately designed and processed according to the requirements of the application occasion; when the application occasion is liquid single-phase forced convection heat transfer, the surface periodic microtexture is designed as a hydrophilic structure conforming to the Wenzel model to increase the wetting area ratio of the fluid and the solid, thereby increasing the heat dissipation area of the microchannel; when the application occasion is liquid two-phase flow boiling heat transfer, the surface periodic microtexture is designed as a hydrophobic structure conforming to the Cassie-Baxter model to reduce the flow resistance, promote bubble generation and detachment, and strengthen the boiling heat transfer coefficient; the surface profile of the periodic microtexture is a triangular wave; the ratio of the depth to the width of the microchannel is the aspect ratio, and the aspect ratio is greater than 15.

2. The microchannel heat sink with a microtextured surface of claim 1, wherein, The microchannel is provided with a microstructure of one or a combination of rectangular, circular, trapezoidal and wavy shapes in the cross section perpendicular to the fluid direction.

3. The microchannel heat sink having a microtextured surface of claim 2, wherein, The microstructure of each group of microchannels is provided with a plurality of microstructures in the height direction of the microchannel substrate.

4. The microchannel heat sink with a microtextured surface of claim 1 wherein, The microchannel substrate comprises a plurality of microcolumns arranged in parallel and spaced array, the microchannels are formed between adjacent microcolumns, and the cross section of the microcolumn in the direction parallel to the bottom surface of the microchannel substrate is rhombic.

5. A method of making a microchannel heat spreader having a microtextured surface as claimed in any one of claims 1 to 4, characterized in that, Specifically comprising the following steps: S1: design the geometric structure of the microchannel and the surface microtexture parameters according to the application occasion, select the type of fixed abrasive wire saw and the dry and wet processing method according to the material of the microchannel substrate, select the specifications of the abrasive wire saw and the wire roller according to the structure parameters of the microchannel, and process the trajectory according to the microchannel structure design; S2: install the workpiece on the workbench of the fixed abrasive wire saw multi-wire cutting machine tool; S3: import the machining track parameters of the workpiece on the solid abrasive wire saw cutting machine tool, set the wire tension, wire speed v s , workpiece feed speed v f and wire saw motion reciprocating period T r : according to the material properties of the workpiece, find the relationship formula of microstructure peak valley value PV, wavelength λ and machining parameters: PV= k 1· v f a · v s b · T r c , λ= k 2· v f m · v s n · T r f ; wherein, k 1、 a 、 b 、 c is an empirical parameter related to the material, k 2、 m 、 f approximately equal to 1, n approximately equal to 0, to back-calculate the machining parameters; S4: operate the control panel to lower the lower bottom surface of the workpiece to a position close to the fixed abrasive wire saw wire mesh; S5: run the processing program: the fixed abrasive wire saw wire mesh is driven by the machine tool driving system to perform periodic reciprocating motion, the workpiece starts to feed, the wire saw wire mesh contacts the workpiece and starts to remove material, and the wire saw forms regular microstructures by lateral movement during reciprocating motion; S6: after the processing program is completed, the workpiece is taken out, cleaned, dried, and the final microchannel substrate is obtained; S7: encapsulate the microchannel substrate, the upper cover plate and the liquid flow cavity to obtain the final microtextured surface super-large aspect ratio microchannel heat sink.

6. The preparation method according to claim 5, characterized in that, When the microchannel substrate material is a non-metallic material with high hardness, the abrasive wire saw in step S1 is an active abrasive wire saw, the dry and wet processing method is dry processing, and the active abrasive can catalyze the phase change of the substrate material under the action of pressure and temperature, thereby reducing the processing difficulty.

7. The preparation method according to claim 5, characterized in that, When the micro-pillars are processed on the micro-channel substrate in a parallel and spaced array, and the cross-section of the micro-pillars in the direction parallel to the bottom surface of the micro-channel substrate is rhombic, in step S5, the processing is divided into two angle perpendicular feed cuttings, to distinguish step 1 and step 2 in two directions on the top view l 1 and l 2, the micro-channel substrate is first installed above the middle of the wire saw wire net, and the front side is parallel to the side of the wire roller; then the workbench is rotated by an angle σ to start l 1 corresponding processing; when the preset processing depth is reached, the wire saw wire net stops moving, and the workbench rises back to the coordinate origin, i.e. the processing of step 1 is completed; then the workbench is rotated by an angle θ based on l 1 to start l 2 corresponding processing; when the preset processing depth is reached, the processing of step 2 is completed, and the rhombic pillar array micro-channel structure is finally processed.

Images