Diamond / copper radiator manufacturing method based on 3D printing

Abstract

The invention belongs to the technical field of additive manufacturing, and particularly relates to a diamond / copper radiator manufacturing method based on 3D printing, and the diamond / copper radiator manufacturing method comprises the steps that diamond / copper composite powder is prepared, and the composite powder comprises diamond particles with nano alloying elements attached to the surfaces and spherical copper powder; and under shielding gas, green laser with the wavelength of 532 nm is adopted for conducting selective laser melting scanning on the composite powder, meanwhile, high-frequency ultrasonic vibration is applied to a molten pool in a laser acting area, and a diamond / copper composite material radiator green body is formed through layer-by-layer powder laying, scanning melting, ultrasonic assistance and layer-by-layer accumulation. Copper matrix crystal grains are refined through ultrasonic energy, residual stress in the printing process is reduced, generation of microcracks is effectively restrained, the mechanical property and reliability of a workpiece are improved, the high absorptivity of green laser to copper and the technical advantages of 3D printing are combined, and high-quality 3D printing is achieved. And the radiator with fine structures such as complex three-dimensional micro-channels and ultrathin fins can be integrally manufactured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of additive manufacturing, in particular to a diamond / copper heat sink manufacturing method based on 3D printing. BACKGROUND

[0002] The precision manufacturing of superhard materials is receiving strong support from national strategies and industrial policies worldwide, particularly in China, to promote their application and technological development in high-end manufacturing. This support aims to address the challenges faced by superhard materials (such as diamond / copper composites) in preparation, performance optimization, and application, thereby meeting the growing demand for high-performance materials in key areas such as aerospace, electronic information, and biomedicine. With the rapid development of artificial intelligence, 5G communication, and aerospace, the power density of electronic chips continues to increase, with heat flux densities approaching or exceeding 1000 W / cm². This poses extremely stringent requirements for heat dissipation materials. Diamond has extremely high thermal conductivity, making it an ideal thermal management material. Copper, as a common metal matrix, has good thermal conductivity and processability. Therefore, diamond / copper composites are considered a key material for solving the heat dissipation problems of next-generation high-power chips.

[0003] However, traditional methods for preparing diamond / copper composites face numerous challenges: (1) copper and diamond have poor natural wettability, resulting in weak interfacial bonding and high interfacial thermal resistance; (2) traditional manufacturing processes, such as hot pressing and sintering, are difficult to form integrated heat sink structures with complex three-dimensional flow channels; (3) during high-temperature preparation, diamond is prone to graphitization, which can compromise its high thermal conductivity. Selective laser melting and other 3D printing technologies offer the possibility of manufacturing complex structure heat sinks, but conventional infrared lasers have low absorption rates for copper powder, and the rapid laser melting process can easily lead to defects such as pores and cracks, making it difficult to ensure both "forming" and "property" of the material. Although some existing technologies attempt to use laser 3D printing for metal matrix composites, there are still issues such as narrow process window and poor performance reproducibility when printing high-thermal-conductivity, high-volume-fraction diamond / copper composites. Therefore, we propose a diamond / copper heat sink manufacturing method based on 3D printing. SUMMARY

[0004] To overcome the deficiencies of the prior art, the present application provides a diamond / copper heat sink manufacturing method based on 3D printing, which solves the problem of narrow process window and poor performance reproducibility when using laser 3D printing for metal matrix composites, particularly for high-thermal-conductivity, high-volume-fraction diamond / copper composites.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a diamond / copper heat sink manufacturing method based on 3D printing, comprising the following steps:

[0006] S1: preparing a diamond / copper composite powder, the composite powder comprising diamond particles with nanometer alloying elements attached to the surface and spherical copper powder;

[0007] S2: under the protection of gas, using a green laser with a wavelength of 532 nm to perform selective laser melting scanning on the composite powder, while applying high-frequency ultrasonic vibration to the molten pool in the laser action area, and through layer-by-layer powder laying, scanning melting and ultrasonic assistance, layer-by-layer accumulation to form a diamond / copper composite material heat sink green body;

[0008] S3: post-processing the printed heat sink green body.

[0009] As a preferred technical solution of the present application, in the copper-coated diamond composite powder in S1, the volume fraction of diamond is 40%-60%, and the surface of the diamond particles in S1 is pre-coated with an intermediate layer of Cr, Mo, W or alloy thereof.

[0010] As a preferred technical solution of the present application, in S2, the frequency of high-frequency ultrasonic vibration is 20 kHz-40 kHz, and the power is 50 W-500 W; in S2, the ultrasonic vibration is performed synchronously with the laser scanning in a continuous or pulsed mode.

[0011] As a preferred technical solution of the present application, in S2, the process parameters of the green laser are: laser power 200 W-500 W, scanning speed 500 mm / s-2000 mm / s, scanning pitch 0.05 mm-0.15 mm, and layer thickness 0.02 mm-0.05 mm.

[0012] As a preferred technical solution of the present application, in S2, the ultrasonic vibration is introduced through an ultrasonic transducer integrated in the printing substrate or the powder laying system.

[0013] As a preferred technical solution of the present application, in S2, an ultrasonic-assisted green laser 3D printing system is implemented, which comprises:

[0014] Green laser emitting unit: for generating a laser beam with a wavelength of 532 nm;

[0015] Powder conveying and spreading unit: for conveying and uniformly spreading the copper-coated diamond composite powder;

[0016] Forming cabin: providing an inert gas protection environment;

[0017] Ultrasonic generation and introduction unit: including an ultrasonic generator, a transducer, and an amplitude transformer, the ultrasonic transducer is integrated below the printing substrate or on the powder laying system, for applying high-frequency vibration to the molten pool;

[0018] Motion control unit: control the motion of laser scanning galvanometer and powder laying system;

[0019] Intelligent control unit: built-in process database and AI algorithm, for real-time matching and closed-loop control of laser parameters, ultrasonic parameters and motion parameters.

[0020] As a preferred technical solution of the present application, the ultrasonic generation and introduction unit includes an ultrasonic generator, a transducer and an amplitude transformer, and the transducer is integrated below the printing substrate or on the powder laying system.

[0021] As a preferred technical solution of the present application, the intelligent control unit is built-in with a process database and an AI optimization algorithm, for dynamically adjusting laser power, scanning speed and ultrasonic power according to the real-time monitored molten pool state.

[0022] As a preferred technical solution of the present application, in S2, a partition scanning strategy is adopted to reduce heat accumulation.

[0023] As a preferred technical solution of the present application, the post-processing in S3 at least includes separating the heat sink from the substrate, and performing stress relief annealing in an inert atmosphere.

[0024] Compared with the prior art, the present application provides a 3D printing-based diamond / copper heat sink manufacturing method, which has the following beneficial effects:

[0025] 1. The 3D printing-based diamond / copper heat sink manufacturing method can effectively break the oxide layer on the surface of the copper liquid through ultrasonic cavitation effect, enhance the wettability of the copper liquid to the diamond, and the acoustic streaming effect can strongly stir the molten pool, so that the diamond is uniformly distributed, the agglomerates are broken, and the gas is promoted to escape, thereby significantly reducing the porosity, improving the density and interface bonding strength, finally improving the thermal conductivity of the composite material, and reducing the interface thermal resistance compared with the sample without ultrasonic assistance.

[0026] 2. The 3D printing-based diamond / copper heat sink manufacturing method can refine the copper matrix grains through ultrasonic waves, reduce residual stress during printing, effectively inhibit the generation of micro-cracks, improve the mechanical properties and reliability of the workpiece, and combine the high absorption rate of green laser to copper and the technical advantages of 3D printing to integrally manufacture heat sinks with complex three-dimensional micro-channels, ultra-thin fins and other fine structures, realize near-net shaping, meet the personalized heat dissipation demand, realize precise regulation of "acoustic-optical-powder" multi-physical field through multi-parameter collaborative optimization and intelligent control, improve the consistency of process stability and workpiece performance, and lay a foundation for industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 Process flowchart of the present application

[0028] Fig. 2 Fig. 1 is a structural schematic diagram of an ultrasonic-assisted green laser 3D printing system in the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0030] EMBODIMENT

[0031] Embodiment one

[0032] Please refer to Figs. 1-2 , a micro-channel heat sink for high-power GaN chips is manufactured, a copper-coated diamond composite powder with a diamond content of 50vol% is selected, the diamond particle size is 80μm, a 100nm-thick Cr layer is pre-plated on the surface, the powder has good sphericity, a modified green laser SLM equipment is used, an ultrasonic-assisted module is integrated into the substrate, the ultrasonic frequency is 25kHz, the maximum power is 300W, the control system has a laser-ultrasonic synchronization function, the laser power is 350W, the scanning speed is 1000mm / s, the scanning pitch is 0.08mm, the layer thickness is 0.03mm; the ultrasonic power is 150W, the ultrasonic power is synchronized with the laser in a pulse mode, the duty cycle is 70%; the protective atmosphere is high-purity argon, the oxygen content is <10ppm, according to the designed three-dimensional model of the micro-channel heat sink, slicing and path planning are performed, UGLPBF printing is performed on the substrate, during the printing process, ultrasonic vibration is transmitted to the molten pool through the substrate, after the printing is completed, the green body is annealed at 500℃ for 2 hours and is cooled in the furnace.

[0033] Embodiment two

[0034] A needle column type water-cooled heat sink for high-power laser is manufactured. Single crystal diamond particles with an average particle size of 50 μm are selected, and are mixed with titanium hydride powder with an average particle size of 80 nm at a mass ratio of 95:5 by low-energy ball mixing for 2 hours. Then, the pretreated diamond powder is mixed with gas-atomized spherical pure copper powder with a particle size of 15-45 μm at a volume ratio of 45:55 in a three-dimensional powder mixer for 4 hours to obtain a uniform composite powder. The composite powder is loaded into an SLM device, a red copper plate is used as a substrate, the forming cabin is vacuumed and then filled with high-purity argon gas to an oxygen content of less than 100 ppm, the laser power is set to 220 W, the scanning speed is 1200 mm / s, the spot diameter is 50 μm, the powder layer thickness is 30 μm, a three-dimensional model of the needle column flow channel heat sink is imported, the needle column diameter is 0.8 mm, the flow channel cross section is 1.5 mm x 1.5 mm, printing is started, a 67° rotating stripe scanning strategy is used for each layer, after printing is completed, the component is wire cut from the substrate, stress relief annealing at 400°C for 1.5 hours is carried out under argon protection, and finally, micro-bead sandblasting polishing treatment is carried out on the internal flow channel.

[0035] Finally, it should be noted that: the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for manufacturing a diamond / copper heat spreader based on 3D printing, characterized by: The method comprises the following steps: S1: preparing a diamond / copper composite powder, which comprises diamond particles with nanoscale alloying elements attached to the surface and spherical copper powder; S2: under a protective atmosphere, using a green laser with a wavelength of 532 nm to perform selective laser melting scanning on the composite powder, while applying high-frequency ultrasonic vibration to the molten pool in the laser action area, and through layer-by-layer powder laying, scanning melting and ultrasonic assistance, layer-by-layer accumulation to form a diamond / copper composite material heat sink green body; S3: post-processing the printed heat sink green body.

2. The method of claim 1, wherein: In the copper-coated diamond composite powder in S1, the volume fraction of diamond is 40%-60%, and the surface of the diamond particles in S1 is pre-coated with an intermediate layer of Cr, Mo, W or an alloy thereof.

3. The method of claim 1, wherein: In S2, the frequency of the high-frequency ultrasonic vibration is 20 kHz-40 kHz, and the power is 50 W-500 W, and the ultrasonic vibration in S2 is synchronized with the laser scanning, using continuous or pulsed mode.

4. The method of claim 1, wherein: In S2, the process parameters of the green laser are: laser power 200 W-500 W, scanning speed 500 mm / s-2000 mm / s, scanning pitch 0.05 mm-0.15 mm, and layer thickness 0.02 mm-0.05 mm.

5. The method of claim 1, wherein: In S2, the ultrasonic vibration is introduced through an ultrasonic transducer integrated in the printing substrate below or the powder laying system.

6. The method of claim 1, wherein: In S2, an ultrasonic-assisted green laser 3D printing system is implemented, which comprises: a green laser emitting unit for generating a laser beam with a wavelength of 532 nm; a powder conveying and spreading unit for conveying and uniformly spreading the copper-coated diamond composite powder; a forming chamber for providing an inert gas protection environment; an ultrasonic generation and introduction unit, which includes an ultrasonic generator, a transducer, and an amplitude transformer, and the ultrasonic transducer is integrated below the printing substrate or on the powder laying system, for applying high-frequency vibration to the molten pool; a motion control unit for controlling the motion of the laser scanning galvanometer and the powder laying system; an intelligent control unit with a built-in process database and AI algorithm for realizing real-time matching and closed-loop control of laser parameters, ultrasonic parameters, and motion parameters.

7. The method of claim 6, wherein: The ultrasonic generation and introduction unit includes an ultrasonic generator, a transducer, and an amplitude transformer, and the transducer is integrated below the printing substrate or on the powder laying system.

8. The method of claim 6, wherein: The intelligent control unit has a built-in process database and AI optimization algorithm for dynamically adjusting the laser power, scanning speed, and ultrasonic power according to the real-time monitored molten pool state.

9. The method of claim 1, wherein: In S2, a zoning scanning strategy is used to reduce heat accumulation.

10. The method of claim 1, wherein: The post-processing in S3 at least includes separating the heat sink from the substrate and performing stress relief annealing in an inert atmosphere.

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