Metal material liquid cooling heat sink with micro-channel structure and preparation method thereof

Abstract

The application discloses a metal material liquid cooling heat dissipation sheet with a micro-channel structure and a preparation method thereof. Metal powder is mixed with a binder to obtain a first mixture, the first mixture is sequentially subjected to banburying, granulation and wire drawing to obtain a metal-based wire material, soluble material and ceramic powder are mixed with a binder to obtain a second mixture, the second mixture is sequentially subjected to banburying, granulation and wire drawing to obtain a micro-channel template wire material, the metal-based wire material and the micro-channel template wire material are respectively placed in feeding ports of a 3D printer, a metal-micro-channel template green body is obtained by printing according to the structure of the metal material liquid cooling heat dissipation sheet, the metal-micro-channel template green body is sequentially subjected to degreasing and sintering to obtain a metal-based diamond-micro-channel template sintered body, the micro-channel template in the metal-based diamond-micro-channel template sintered body is removed, and a metal-based diamond composite material heat dissipation sheet is obtained. The method has the characteristics of forming stability, throughness and size consistency of the micro-channel structure.

Description

Technical Field

[0001] This invention relates to the fields of thermal management and metal additive manufacturing technology, and in particular to a liquid-cooled heat sink with a microchannel structure and its preparation method. Background Technology

[0002] The heat flux density generated by the miniaturization and integration of existing high-power-density electronic devices, power modules, and electric drive systems continues to increase. Traditional air cooling methods are no longer sufficient to meet the requirements for efficient and uniform heat dissipation, and liquid cooling heat sinks are widely used due to their strong heat exchange capacity. Currently, the internal flow channels of liquid cooling heat sinks are mostly formed through machining grooves followed by overlay welding, diffusion welding, or etching. These methods involve many steps and are limited by processing and packaging conditions, making it difficult to achieve integrated manufacturing of complex internal microchannel structures. Furthermore, the connection interfaces easily introduce additional thermal resistance and potential leakage risks. To reduce assembly interfaces, solutions have been developed using multi-material additive manufacturing to construct flow channels or spacer structures and then removing the spacers after forming to obtain cooling channels. However, when the channel feature size is further reduced to the micrometer level and located inside the metal substrate, problems still arise such as unstable spacer structure forming, channel necking or blockage during debinding and sintering, and incomplete spacer removal leading to residues and secondary blockages. It is difficult to simultaneously ensure the continuity, dimensional consistency, and structural integrity of the microchannels. Therefore, there is an urgent need for an integrated fabrication process suitable for microchannel structures inside metal substrates, which can achieve stable forming and controllable connection of microchannel structures by synergistically controlling the forming and pore-forming processes. Summary of the Invention

[0003] To address the problems of unstable forming accuracy, channel necking or blockage, and incomplete removal of sacrificial core material in the integrated fabrication of micron-level internal microchannel structures in existing technologies, the first objective of this invention is to provide a method for fabricating a liquid-cooled heat sink with a microchannel structure. Employing a 3D printing method, a microchannel template is formed as a sacrificial phase using a pore-forming agent during the 3D printing process. The template is removed during post-processing, resulting in an in-situ formation of a three-dimensionally interconnected microchannel network with controllable dimensions and designable morphology within the heat sink. The 3D printing method provided by this invention enables the simultaneous construction of the composite matrix and the template structure, thereby achieving integrated manufacturing of a high thermal conductivity composite material and a reinforced convection heat transfer structure. By synergistically controlling the printing parameters, debinding and sintering process, and dissolution conditions, the forming stability, connectivity, and dimensional consistency of the microchannel structure are improved, while reducing the risk of residue and blockage.

[0004] The second objective of this invention is to provide a liquid-cooled heat sink with a microchannel structure made of metal material prepared by the above-described preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention discloses a method for preparing a liquid-cooled heat sink with a microchannel structure. The method involves mixing metal powder with a binder to obtain a first mixture, then sequentially mixing, granulating, and drawing the first mixture to obtain a metal-based filament. A second mixture is obtained by mixing a soluble material, ceramic powder, and a binder, followed by sequential mixing, granulation, and drawing of the second mixture to obtain a microchannel template filament. The metal-based filament and the microchannel template filament are placed in the feed inlet of a 3D printer. A metal-microchannel template green body is obtained by printing according to the structure of the liquid-cooled heat sink. The green body is then sequentially degreased and sintered to obtain a sintered metal-based microchannel template. The microchannel template is removed from the sintered metal-based microchannel template to obtain the liquid-cooled heat sink.

[0007] The method for preparing a liquid-cooled heat sink made of metal material provided by the present invention adopts 3D printing. The preset spatial structure is first constructed by 3D printing. At the designed microchannel, a microchannel template is formed by printing a second mixture. After sintering, the microchannel template is removed, thereby forming a microchannel inside the metal matrix. This achieves high-precision and controllable-size internal microchannel construction while ensuring the strength of the metal matrix.

[0008] In a preferred embodiment, the binder for the first mixture and the second mixture comprises, by mass percentage, the following: 50-60% thermoplastic polyester elastomer, 30-40% acrylonitrile-butadiene-styrene copolymer, 1-3% plasticizer, 2-5% dispersant, and 1-3% surfactant.

[0009] In a further preferred embodiment, the plasticizer is selected from at least one of polyethylene glycol, tributyl citrate, epoxidized soybean oil, and dioctyl phthalate.

[0010] In a further preferred embodiment, the dispersant is selected from at least one of stearic acid, zinc stearate, polyethylene wax, ethylene-vinyl acetate copolymer wax, and polyvinylpyrrolidone.

[0011] Further preferably, the surfactant is selected from at least one of Span 80, Tween 80, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

[0012] In this invention, the first mixture and the second mixture use the same binder, which makes the shrinkage, expansion and decomposition behavior of the negative template and the matrix completely consistent during the debinding and sintering process, thereby eliminating interfacial stress and cracking risk, improving the molecular-level interfacial bonding strength, and effectively ensuring the precision of the microchannel.

[0013] In a preferred embodiment, the metal in the metal powder is selected from at least one of pure copper, pure aluminum, copper alloy, and aluminum alloy.

[0014] In a preferred embodiment, the mass ratio of the metal powder to the binder is 4~6:1.

[0015] In a preferred embodiment, the first mixture is sequentially subjected to intensive mixing, granulation, and wire drawing to obtain a metal-based wire; the intensive mixing temperature is controlled at 140–190°C, the intensive mixing time is controlled at 30–90 min, and the wire drawing temperature is controlled at 160–220°C.

[0016] In a preferred embodiment, the diameter of the metal-based wire is 1.6 to 2.0 mm.

[0017] In a preferred embodiment, the soluble material is selected from at least one of zinc chloride, potassium hydroxide, potassium chloride, and sodium chloride.

[0018] In a preferred embodiment, the ceramic powder is selected from at least one of Al2O3, ZrO2, and BN.

[0019] In the preferred embodiment, the mass ratio of soluble material to ceramic powder is 90~95:5~10.

[0020] The microchannel template in this invention can be removed during solvent treatment or chemical reaction without damaging the continuity and density of the metal matrix. Experiments have shown that materials such as zinc chloride, potassium hydroxide, potassium chloride, and sodium chloride all have good forming stability and sacrificial phase characteristics, and can be rapidly dissolved and removed by water or solution in the post-treatment stage, achieving low-temperature removal and avoiding damage to the microstructure and interfacial bonding of the composite material. This invention combines soluble salt with ceramic powder as a reinforcing phase to form a microchannel template. Utilizing the reinforcing and toughening effect of ceramic powder on the soluble salt matrix, the high-temperature strength, deformation resistance, and crack resistance of the microchannel template during heat treatment are improved, thus effectively avoiding the problems of softening and loss, local collapse, and crack propagation that easily occur before and after sintering when using a single soluble salt as a template sacrificial phase. By selecting one or more of the above-mentioned mixed pore-forming agents, the pore structure morphology and porosity can be flexibly controlled according to the process temperature, channel size, and removal method, thereby achieving controllable microchannel size, good connectivity, and a simple and reliable preparation process.

[0021] However, experiments have shown that the amount of ceramic powder added as a reinforcing phase should not be too much. If too much is added, it will easily lead to incomplete removal, resulting in residue and affecting the flow channel performance.

[0022] In a preferred embodiment, the total mass ratio of the soluble material and ceramic powder to the mass ratio of the binder is 1:3~4.

[0023] In a preferred embodiment, the second mixture is sequentially subjected to intensive mixing, granulation, and filament drawing to obtain microchannel template filaments; the intensive mixing temperature is controlled at 160–220℃, and the intensive mixing time is controlled at 20–60 min.

[0024] In a preferred embodiment, the diameter of the microchannel template filament is 1.7–1.8 mm.

[0025] In a preferred embodiment, a multi-nozzle FDM 3D printer is used for printing; the printing nozzle temperature of the metal-based filament is 160–230°C, the printing nozzle temperature of the microchannel template filament is 150–220°C, the printing platform temperature is 40–90°C, the printed layer thickness is 0.05–0.15 mm, the nozzle diameter is 0.20–0.60 mm, the printing speed is 10–50 mm / s, and the infill rate is 90–100%; the slice linewidth is 0.8–1.2 times the nozzle diameter. The microchannel template filament is continuously printed at preset microchannel positions to form a microchannel template, which is then covered by the metal-based filament to obtain a metal-microchannel template green body.

[0026] In actual operation, a three-dimensional model of the liquid cooling heat sink and its microchannel structure is created in the computer, imported into slicing software to complete the slicing and printing parameter settings, and then imported into a 3D printer based on FDM molding technology. During slicing and printing, the forming accuracy of the microchannel template is controlled by the coordinated matching of slicing linewidth, nozzle orifice diameter and layer thickness parameters to reduce the risk of necking and morphological distortion of the microchannels in the subsequent debinding and sintering process. A dual-material 3D printer is used for printing, so that the metal matrix printing material is printed to form the metal blank skeleton of the heat sink, and the microchannel template filament is printed at the predetermined position of the microchannel to form the microchannel sacrificial core material, thereby obtaining a composite blank containing the metal blank and the microchannel template.

[0027] In a preferred embodiment, the degreasing atmosphere is hydrogen, nitrogen, or vacuum. The degreasing process is as follows: first, the temperature is raised to 100–120°C and held for 0.5–1 hour; then, the temperature is raised to 200–250°C and held for 0.5–2 hours; next, the temperature is raised to 350–400°C and held for 0.5–2 hours; finally, the temperature is raised to 500–600°C and held for 0.5–2 hours, with the entire process controlled at a heating rate of 1–10°C / min. This staged degreasing reduces the risk of internal pressure and cracking caused by instantaneous gas release, avoids channel collapse and structural deformation, improves degreasing uniformity and densification quality, thereby ensuring the stability of the microchannel morphology and the overall mechanical and thermal conductivity of the composite material.

[0028] After degreasing, the metal is sintered and densified. The sintering temperature is determined according to the metal system, and sintering is carried out in a vacuum or protective atmosphere. After sintering, the metal is cooled in the furnace.

[0029] In a preferred embodiment, the process of removing the microchannel template involves placing the metal-based microchannel template sintered blank in a solvent and immersing it at 20–80°C, preferably 40–60°C, for 2–24 hours.

[0030] The solvent is selected from water, alkaline solution, and acid solution. The mass fraction of alkali in the alkaline solution is 1% to 5%, and the mass fraction of acid in the acid solution is 1% to 5%.

[0031] In actual operation, after dissolution, the solution is repeatedly rinsed with deionized water to eventually form microchannels. After dissolution, the solution is cleaned and dried. The drying method is vacuum drying or hot air drying.

[0032] The present invention also provides a liquid-cooled heat sink with a microchannel structure made of metal material prepared by the above preparation method, wherein the liquid-cooled heat sink includes a metal substrate and continuous microchannels disposed inside the metal substrate.

[0033] In a preferred embodiment, the hydraulic diameter of the microchannel is 100–500 μm, and the spacing between adjacent channels is 100–500 μm.

[0034] Experiments have shown that when the hydraulic diameter is too small, the channel cross-sectional area decreases, flow resistance and pressure drop increase significantly, pumping power consumption increases, blockage or particle deposition is prone to occur, and high cleanliness of the coolant is required. At the same time, the forming accuracy of 3D printing and pore-forming agents is limited at the microscale, and defects such as collapse, pore blockage or channel non-connection are prone to occur, affecting the consistency and reliability of forming. On the other hand, when the hydraulic diameter is too large, the specific surface area and fluid disturbance are weakened, the convective heat transfer coefficient decreases, it is difficult to form an enhanced heat transfer effect, the heat dissipation mode is close to that of ordinary macroscopic flow channels, and the advantages of efficient heat dissipation of microchannels cannot be fully utilized, resulting in a reduction in heat dissipation capacity per unit volume.

[0035] In a preferred embodiment, the cross-sectional shape of the microchannel is at least one of a circle, an ellipse, a rectangle, or a trapezoid; the microchannel is at least one of a straight channel, a serpentine channel, a fractal channel, or a regular or biomimetic 3D microstructure array.

[0036] The beneficial effects of this invention are:

[0037] (1) The microchannel structure is integrally formed with the metal substrate, reducing the welding and encapsulation interface, and reducing the risk of leakage and interface thermal resistance;

[0038] (2) Complex three-dimensional microchannel networks can be realized, and the channel topology can be designed to improve temperature uniformity and heat exchange efficiency;

[0039] (3) In view of the problem that micron-level internal microchannels are prone to residue and blockage in the post-processing stage, the present invention adopts chemical leaching to selectively remove sacrificial core material, and combines it with circulating rinsing, ultrasonic or negative pressure suction to improve the completeness of leaching and the permeability of microchannels, and reduce the risk of residue and blockage.

[0040] (4) The process chain of dual-material printing and dissolution pore forming method is clear and can be standardized for production;

[0041] (5) The channel size and wall thickness can be controlled by the nozzle orifice diameter, layer thickness and slicing parameters to improve consistency and yield. Attached Figure Description

[0042] Figure 1 This is a front view of a metal liquid-cooled heat sink with a linear microchannel structure.

[0043] Figure 2 This is a cross-sectional view of a metal liquid-cooled heat sink with a linear microchannel structure. Detailed Implementation

[0044] Example 1

[0045] This embodiment provides a copper-based liquid-cooled heat sink with an internal parallel array microchannel structure and its fabrication method. The characteristic dimensions of the internal microchannels of the heat sink are controlled within the range of 100–500 μm, wherein the channel width is 250 μm, the channel height is 300 μm, and the spacing between adjacent channels is 300 μm.

[0046] (1) Copper powder (100-150 μm) was selected as the metal powder. By mass percentage, copper powder accounted for 83 wt% and binder accounted for 17 wt%.

[0047] Potassium chloride powder and Al2O3 powder are used as pore-forming agents, wherein the mass ratio of potassium chloride powder to Al2O3 powder is 93:7, and the mass ratio of pore-forming agent to binder is 1:3.

[0048] The adhesive comprises, by weight percentage: 55% thermoplastic polyester elastomer, 35% acrylonitrile-butadiene-styrene copolymer, 2% plasticizer, 5% dispersant and 3% surfactant.

[0049] (2) Mixing and kneading: Mix copper powder with metal matrix special binder and knead at 168°C for 50 min to obtain metal matrix compound; knead pore-forming agent and binder at 100°C for 25 min to obtain pore-forming agent compound.

[0050] (3) Granulation and drawing: The above-mentioned compound is granulated and drawn into wire to obtain metal matrix wire and pore-forming agent wire, both with a diameter of 1.75 mm.

[0051] (4) Establish a three-dimensional model of the heat sink and set up a parallel array microchannel structure inside it. The corresponding area is formed by the printing path of the pore-forming agent sacrificial core material. A dual-nozzle FDM three-dimensional printer is used to print the composite green body. The printing layer thickness is 0.08 mm, the nozzle diameter of the pore-forming agent is 0.20 mm, and the nozzle diameter of the metal substrate is 0.30 mm. When slicing, the path width is set to match the nozzle orifice diameter, and the forming size of the sacrificial core material is controlled in conjunction with the layer thickness parameter to improve the microchannel forming accuracy and reduce the risk of necking and morphological distortion in the subsequent sintering process.

[0052] (5) Degreasing and sintering: After the composite green body is degreased in stages, it is sintered at 960℃ in a vacuum sintering furnace to obtain copper-based components.

[0053] (6) Dissolution and pore formation: The sintered components are placed in deionized water at 55°C for dissolution treatment, and are supplemented by circulating rinsing and ultrasonic assistance to enhance mass transfer during the removal of sacrificial core material and reduce the risk of microchannel residue and blockage; after removing the pore-forming agent sacrificial core material, the copper-based metal liquid cooling heat sink with a parallel array microchannel structure inside is obtained by cleaning and drying.

[0054] The resulting heat sink has a complete overall structure, the pore-forming agent and sacrificial core material can be effectively removed, the internal microchannel structure is continuous, and the channel feature dimensions are kept within the design range.

[0055] Testing revealed that the fabricated copper-based liquid-cooled heat sink with a parallel array microchannel structure exhibited a channel size deviation of 1.4% and a microchannel connectivity of 98.6% through micro-CT analysis. EDS analysis showed a potassium chloride residue of 0.01 wt%. Steady-state thermal conductivity testing yielded an equivalent thermal conductivity of 386 W / m·K. The convective heat transfer coefficient, measured on a liquid-cooling experimental platform, was 2.1 × 10⁻⁶. 5 W / m²·K; its thermal resistance was measured to be 0.09℃·cm² / W using the steady-state electric heating method.

[0056] Example 2

[0057] This embodiment provides an aluminum-based liquid-cooled heat sink with an internal staggered array microchannel structure and its fabrication method. The characteristic dimensions of the microchannels inside the heat sink are controlled within the range of 100–500 μm, wherein the channel width is 200 μm, the channel height is 250 μm, and the spacing between adjacent channels is 250 μm.

[0058] (1) Ingredients: Aluminum powder (100-150 μm) is selected as the metal powder. By mass percentage, aluminum powder accounts for 83 wt% and binder accounts for 17 wt%.

[0059] Zinc chloride powder and BN powder are used as pore-forming agents, with a mass ratio of zinc chloride powder to BN powder of 91:9 and a mass ratio of pore-forming agent to binder of 1:3.

[0060] The adhesive comprises, by weight percentage: 52% thermoplastic polyester elastomer, 38% acrylonitrile-butadiene-styrene copolymer, 2% plasticizer, 5% dispersant and 3% surfactant.

[0061] (2) Mixing and kneading: After mixing aluminum powder with metal matrix special binder, knead at 165°C for 45 min to obtain aluminum matrix compound; knead pore-forming agent with pore-forming agent special binder at 105°C for 30 min to obtain pore-forming agent compound.

[0062] (3) Granulation and drawing: The above-mentioned compound is granulated and drawn into wire to obtain aluminum matrix wire and pore-forming agent wire, both with a diameter of 1.75 mm.

[0063] (4) Modeling and printing: A three-dimensional model of the heat sink was established, and an interlaced array of microchannel structures was set inside. A dual-nozzle FDM three-dimensional printer was used to print the composite green body. The printing layer thickness was 0.08 mm, the nozzle diameter of the pore-forming agent was 0.20 mm, and the nozzle diameter of the metal substrate was 0.30 mm. During slicing, the size of the sacrificial core material was adjusted in a coordinated manner by controlling the path linewidth and combining the nozzle orifice diameter and layer thickness parameters, so as to improve the microchannel forming accuracy and reduce the risk of microchannel necking and morphological distortion after sintering.

[0064] (5) Degreasing and sintering: After the composite green body is degreased in sections, it is sintered at 620°C under vacuum or inert atmosphere protection to obtain aluminum matrix components.

[0065] (6) Dissolution and pore formation: The sintered components are placed in deionized water at 50°C for dissolution treatment, and circulatory rinsing is used to enhance the removal of sacrificial core material inside the microchannel and reduce the risk of residue and blockage. After removing the sacrificial core material of the pore-forming agent, the aluminum-based metal liquid heat sink with an interlaced array microchannel structure is obtained after cleaning and drying.

[0066] The resulting heat sink has a complete overall structure, well-formed internal microchannel structure, and the sacrificial core material of the pore-forming agent can be effectively removed, while the channel feature dimensions remain within the design range.

[0067] Testing revealed that the aluminum-based liquid-cooled heat sink with an interlaced array microchannel structure exhibited a channel size deviation of 1.8% and a microchannel connectivity of 97.5% under microscopic CT analysis. EDS analysis showed a zinc chloride residue of 0.03 wt%. Steady-state thermal conductivity testing yielded an equivalent thermal conductivity of 218 W / m·K. The convective heat transfer coefficient, measured on a liquid-cooling experimental platform, was 1.7 × 10⁻⁶. 5W / m²·K; its thermal resistance was measured to be 0.12℃·cm² / W using the steady-state electric heating method.

[0068] Comparative Example 1

[0069] This comparative example provides a copper-based liquid-cooled heat sink with an internal parallel array microchannel structure and its preparation method. The internal microchannel design dimensions of the heat sink are the same as in Example 1, wherein the channel width is 250 μm, the channel height is 300 μm, and the spacing between adjacent channels is 300 μm. The difference from Example 1 is that in this comparative example, only potassium chloride powder is used as the pore-forming agent, and Al2O3 ceramic powder is not added as a reinforcing phase.

[0070] (1) Copper powder (100-150 μm) was selected as the metal powder. By mass percentage, copper powder accounted for 83 wt% and binder accounted for 17 wt%.

[0071] Potassium chloride powder is used as a pore-forming agent, and the mass ratio of the pore-forming agent to the binder is 1:3.

[0072] The adhesive comprises, by weight percentage: 55% thermoplastic polyester elastomer, 35% acrylonitrile-butadiene-styrene copolymer, 2% plasticizer, 5% dispersant and 3% surfactant.

[0073] (2) Mixing and kneading: Mix copper powder with metal matrix special binder and knead at 168°C for 50 min to obtain metal matrix compound; knead potassium chloride powder with binder at 100°C for 25 min to obtain pore-forming agent compound.

[0074] (3) Granulation and drawing: The above-mentioned compound is granulated and drawn into wire to obtain metal matrix wire and pore-forming agent wire, both with a diameter of 1.75 mm.

[0075] (4) Establish a three-dimensional model of the heat sink and set up a parallel array microchannel structure inside it. The corresponding area is formed by the printing path of the pore-forming agent sacrificial core material. A dual-nozzle FDM three-dimensional printer is used to print the composite green body. The printing layer thickness is 0.08 mm, the nozzle diameter of the pore-forming agent is 0.20 mm, and the nozzle diameter of the metal substrate is 0.30 mm. When slicing, the path width matching the nozzle orifice diameter is set, and the forming size of the sacrificial core material is controlled in a coordinated manner in combination with the layer thickness parameter.

[0076] (5) Degreasing and sintering: After the composite green body is degreased in stages, it is sintered at 960℃ in a vacuum sintering furnace to obtain copper-based components.

[0077] (6) Dissolution and pore formation: The sintered components are placed in deionized water at 55°C for dissolution treatment, supplemented by circulating rinsing and ultrasonic assistance; after removing the sacrificial core material of potassium chloride, the copper-based metal liquid cooling heat sink with a parallel array microchannel structure inside is obtained after cleaning and drying.

[0078] The resulting heat sink had a generally intact overall structure. However, due to the absence of Al2O3 ceramic powder reinforcement in the pore-forming agent, the single potassium chloride sacrificial core material exhibited weak resistance to deformation during degreasing and sintering, resulting in localized necking, collapse, and residual blockage in the microchannels. Microscopic CT analysis revealed a microchannel size deviation of 6.8% and a channel connectivity of 86%. EDS analysis showed a potassium chloride residue of 0.16 wt%. Steady-state thermal conductivity testing yielded an equivalent thermal conductivity of 315 W / m·K, while the convective heat transfer coefficient, measured using a liquid-cooled experimental platform, was 1.1 × 10⁻⁶. 5 W / m²·K; its thermal resistance, measured using the steady-state electric heating method, is 0.18 ℃·cm² / W. Compared to Example 1, the heat sink obtained in this comparative example showed a decrease in channel size consistency, connectivity, complete removal of the pore-forming agent, and liquid cooling performance. This indicates that adding an appropriate amount of Al₂O₃ ceramic powder as a reinforcing phase to the potassium chloride pore-forming agent is beneficial for improving the structural stability of the sacrificial core material during post-processing and reducing the risk of microchannel necking, collapse, and residual blockage.

Claims

1. A method for preparing a liquid-cooled heat sink made of metal material with a microchannel structure, characterized in that: Metal powder and binder are mixed to obtain a first mixture. The first mixture is then subjected to intensive mixing, granulation, and wire drawing to obtain a metal-based filament. Soluble material, ceramic powder, and binder are mixed to obtain a second mixture. The second mixture is then subjected to intensive mixing, granulation, and wire drawing to obtain a microchannel template filament. The metal-based filament and the microchannel template filament are placed in the feed inlet of a 3D printer. Based on the structure of the metal liquid-cooled heat sink, a metal-microchannel template green body is obtained through printing. The metal-microchannel template green body is then subjected to debinding and sintering to obtain a sintered metal-based microchannel template. The microchannel template in the sintered metal-based microchannel template is removed to obtain the metal liquid-cooled heat sink.

2. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The binders for the first and second mixtures, by mass percentage, are composed of the following: 50-60% thermoplastic polyester elastomer, 30-40% acrylonitrile-butadiene-styrene copolymer, 1-3% plasticizer, 2-5% dispersant, and 1-3% surfactant.

3. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The metal in the metal powder is selected from at least one of pure copper, pure aluminum, copper alloy, and aluminum alloy; The mass ratio of the metal powder to the binder is 4~6:

1.

4. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The first mixture is sequentially subjected to intensive mixing, granulation, and wire drawing to obtain metal-based wire; the intensive mixing temperature is controlled at 140-190℃, the intensive mixing time is 30-90 min, and the wire drawing temperature is 160-220℃. The diameter of the metal-based wire is 1.6 to 2.0 mm.

5. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The soluble material is selected from at least one of zinc chloride, potassium hydroxide, potassium chloride, and sodium chloride; The ceramic powder is selected from at least one of Al2O3, ZrO2, and BN; The mass ratio of soluble material to ceramic powder is 90~95:5~10; The total mass ratio of the soluble material and ceramic powder to the binder is 1:3~4.

6. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The second mixture is subjected to intensive mixing, granulation, and drawing to obtain microchannel template filaments; the intensive mixing temperature is controlled at 160-220℃ and the intensive mixing time is controlled at 20-60min; The diameter of the microchannel template filament is 1.7–1.8 mm.

7. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: During printing, a multi-nozzle FDM 3D printer is used; the printing nozzle temperature for the metal-based filament is 160–230°C, the printing nozzle temperature for the microchannel template filament is 150–220°C, the printing platform temperature is 40–90°C, the printing layer thickness is 0.05–0.15 mm, the nozzle diameter is 0.20–0.60 mm, the printing speed is 10–50 mm / s, and the fill rate is 90–100%; the slice linewidth is 0.8–1.2 times the nozzle diameter.

8. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The degreasing atmosphere is hydrogen, nitrogen, or vacuum. The degreasing process involves first heating to 100–120°C and holding for 0.5–1 hour, then heating to 200–250°C and holding for 0.5–2 hours; then heating to 350–400°C and holding for 0.5–2 hours; and finally heating to 500–600°C and holding for 0.5–2 hours. The entire process is controlled, and the heating rate is 1–10°C / min.

9. The method for preparing a liquid-cooled heat sink with a microchannel structure of metal material according to claim 1, characterized in that: The process of removing the microchannel template is to place the metal-based microchannel template sintered blank in a solvent and soak it at 20-80°C for 2-24 hours. The solvent is selected from water, alkaline solution, and acid solution. The mass fraction of alkali in the alkaline solution is 1% to 5%, and the mass fraction of acid in the acid solution is 1% to 5%.

10. The liquid-cooled heat sink with a microchannel structure prepared by the preparation method according to any one of claims 1-9, characterized in that: The liquid-cooled heat sink made of metal material includes a metal substrate and continuous microchannels disposed inside the metal substrate. The hydraulic diameter of the microchannel is 100–500 μm, and the spacing between adjacent channels is 100–500 μm; The cross-sectional shape of the microchannel is at least one of circular, elliptical, rectangular, or trapezoidal; the microchannel is at least one of linear channel, serpentine channel, fractal channel, regular or biomimetic 3D microstructure array.

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