Machining method of diamond jet flow micro-channel radiator for high-heat-flux heat dissipation

Abstract

The invention discloses a machining method of a diamond jet micro-channel radiator for high-heat-flux heat dissipation. The machining method comprises the steps that the surface of a CVD diamond substrate is cleaned; carrying out double-sided mechanical polishing on the CVD diamond substrate; performing single-hole and single-channel trial processing on the CVD diamond substrate; removing the residual graphite layer in the jet flow layer and the micro-channel layer; putting the jet flow layer and the micro-channel layer into deionized water for ultrasonic cleaning, and putting the jet flow layer and the micro-channel layer into a drying box for drying; mixing an epoxy resin matrix with a curing agent, and doping diamond powder to form composite slurry; uniformly coating the interface of the jet flow layer and the micro-channel layer with composite slurry, and dispensing ultraviolet curing adhesive at four corners of the joint surface; carrying out mechanical positioning to realize preliminary fixation of a joint surface; transferring the assembly to a constant-temperature drying oven to complete thermocuring treatment of the epoxy resin system to obtain the jet flow micro-channel radiator; and placing the assembled jet flow micro-channel radiator in a packaging device, and connecting a gear pump to drive fluid to carry out a sealing test.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-power electronic device heat dissipation, and particularly relates to a processing method for a diamond jet microchannel heat sink for high heat flux density heat dissipation, which is applicable to high heat flux density heat dissipation scenarios such as high-power communication devices, high-power lasers, and aerospace electronic devices. Background Art

[0002] Under the current technical background, traditional metal-based (such as copper, aluminum) and silicon-based microchannel heat sinks are difficult to meet the heat dissipation requirements of ultra-high heat flux density electronic devices due to the limitations of their thermal conductivity and the problem of mismatch in thermal expansion coefficient. Although diamond materials have attracted much attention for their excellent thermal conductivity, their super-hard characteristics pose challenges to precision machining. Traditional mechanical machining methods are prone to cause edge cracking of diamonds, and laser machining is likely to produce a heat-affected zone and leave a graphite residue layer on the machining surface. These factors significantly reduce the heat dissipation efficiency. In addition, existing interlayer connection technologies (such as brazing) are prone to cause blockage of microchannels at the microscale. Therefore, there is an urgent need to develop an integrated process that integrates high-precision laser machining, efficient graphite removal, and low-defect connection to meet the heat dissipation problems of high heat flux density electronic devices. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to propose a preparation method for a diamond jet microchannel heat sink in view of the above deficiencies in the prior art. Combining the advantages of jet impingement cooling technology with high heat dissipation efficiency and good temperature uniformity and microchannel heat dissipation technology with a large specific surface area, a new solution is provided for the thermal management of high heat flux density electronic devices. Using a green diamond laser cutting device and a high-power microscope, with chemical vapor deposition (CVD) diamond as the base material. By precisely controlling the laser power, scanning speed, and scanning times, precise machining of microscale jet holes and microchannels is achieved. The specific steps include equipment and material preparation, laser parameter debugging, heat sink machining, graphite layer removal, and precise hole alignment and assembly. Finally, high-precision machining of jet holes and microchannels is realized, and the machining residual graphite layer is effectively removed, meeting the heat dissipation performance and reliability of high heat flux density heat sinks.

[0004] To solve the above problems, the present invention provides a processing method for a diamond jet microchannel heat sink for high heat flux density heat dissipation, including:

[0005] Ultrasonically clean the surface of the CVD diamond substrate with acetone or alcohol to thoroughly remove contaminants and avoid carbonization of impurities during cutting, which may affect the light path;

[0006] Mechanically polish both sides of the CVD diamond substrate to reduce the surface roughness to Ra≤0.2μm to improve the uniformity of laser energy absorption and reduce scattering loss;

[0007] Perform trial processing on a single hole and a single channel of a CVD diamond substrate, observe the processing results using a high-power microscope, and dynamically adjust processing parameters such as the laser power, scanning speed, and scanning times of the laser equipment to ensure the processing accuracy of the jet holes and microchannels.

[0008] Immerse the processed jet layer and microchannel layer in aqua regia at room temperature for 2 - 3 hours, or immerse the jet layer or microchannel layer in other strong acidic solutions for a period of time to remove the residual graphite layer in the jet layer and microchannel layer.

[0009] Neutralize the waste acidic solution and then place it in a waste liquid pool. Ultrasonically clean the jet layer and microchannel layer in deionized water, and finally dry them in a drying oven.

[0010] First, mix the epoxy resin matrix and the curing agent in a predetermined ratio, and incorporate a certain amount of diamond powder to form a composite slurry. Subsequently, uniformly coat the epoxy resin - diamond composite slurry in the interface area between the jet layer and the microchannel layer, and at the same time, apply ultraviolet - curable glue at the four corners of the joint surface as an auxiliary adhesive. To ensure the alignment of the interlayer structure, select a metal wire with a diameter smaller than the jet hole diameter to penetrate the two layers from the four corners for mechanical positioning, and then achieve the preliminary fixation of the joint surface through ultraviolet irradiation. Finally, transfer the component to a constant - temperature oven to complete the thermal curing treatment of the epoxy resin system, and finally obtain a jet microchannel heat sink with both high bonding strength and excellent heat - conduction characteristics.

[0011] Place the assembled jet microchannel heat sink in a packaging device, connect a gear pump to drive the fluid for a sealing test to ensure no leakage and sufficient mechanical strength.

[0012] Both the jet layer and the microchannel layer of the jet microchannel heat sink are made of CVD diamond, and the thickness dimension ranges of both the jet layer and the microchannel layer are within 2 - 4 mm.

[0013] The jet microchannel heat sink includes a jet layer and a microchannel layer. The jet holes in the jet layer are conical, and the microchannels in the microchannel layer are rectangular in shape.

[0014] The surface thickness uniformity of the jet microchannel heat sink is within ±1%.

[0015] The trial processing of a single hole and a single channel on the CVD diamond substrate, observing the processing results using a high - power microscope, and dynamically adjusting processing parameters such as the laser power, scanning speed, and scanning times of the laser equipment to ensure the processing accuracy of the jet holes and microchannels includes:

[0016] Adjust the depth of the microchannels in the microchannel layer to within ±8 μm, and adjust the size of the jet holes to within ±3 μm.

[0017] Soaking the processed jet layer and microchannel layer in aqua regia at room temperature for 2-3 hours, or soaking the jet layer or microchannel layer in other strong acidic solutions for a period of time to remove the residual graphite layer in the jet layer and microchannel layer, including:

[0018] Adjust the carbon content on the surface of the jet holes of the jet layer and the microchannels of the microchannel layer after aqua regia corrosion treatment to ≤ 5%.

[0019] The predetermined ratio is that the mass ratio of the epoxy resin matrix to the curing agent is 6:1, and the added amount of the quantified diamond powder is 5wt%.

[0020] The diameter range of the metal wire is 0.05-0.9mm, the material is piano wire or stainless steel wire, and the hole alignment accuracy deviation ≤ ±5μm.

[0021] The curing time range of the ultraviolet curable adhesive is 30-60 seconds, and the thermal curing condition of the epoxy resin system is 60℃ / 2h.

[0022] The sealing test pressure range of the jet microchannel radiator is 0.5-1MPa, and the leakage rate ≤ 1×10-6Pa·m 3 / s.

[0023] The inlet diameter range of the conical structure of the jet hole is 0.2-0.5mm, the outlet diameter range is 0.1-0.3mm, and the inlet diameter of the conical structure is always larger than the outlet diameter; the width range of the rectangular cross-section of the microchannels in the microchannel layer is 0.3-0.5mm, and the depth range is 0.3-1.7mm.

[0024] The overall size of the jet microchannel radiator is 10mm×10mm×4mm, which is applicable to high heat flux density heat dissipation scenarios such as high-power communication equipment, high-power lasers, and aerospace electronic equipment.

[0025] The beneficial effects of the present invention are:

[0026] This jet microchannel heat exchanger combines the high-efficiency heat dissipation performance and temperature uniformity advantages of jet impingement cooling technology, as well as the large specific surface area characteristics of microchannel heat dissipation technology, providing an innovative solution for the thermal management of high heat flux density electronic devices.

[0027] Using a green laser to cut chemical vapor deposition (CVD) diamond effectively reduces the heat affected area. By dynamically adjusting the processing parameters, precise control of the jet hole size and microchannel size is achieved.

[0028] This jet microchannel heat exchanger significantly improves the impact effect of the cooling medium on the microchannel jet and the temperature uniformity of the heat exchanger by laser machining different jet hole sizes, and reduces the pressure loss in the jet holes.

[0029] This jet microchannel heat exchanger significantly increases the convective heat transfer area of the radiator, reduces the thermal resistance of the radiator, and improves the performance of the radiator by laser machining microchannels with different aspect ratios.

[0030] Due to the superior thermal conductivity of diamond, this radiator has better heat dissipation performance compared to radiators made of other materials.

[0031] Using epoxy resin-diamond micropowder composite slurry as the connection medium between the jet layer and the microchannel layer effectively reduces the complexity of the processing process, significantly improves the bonding strength between interfaces, and reduces the interfacial thermal resistance.

[0032] Through process innovation and structural design, problems such as low machining accuracy, high graphite residue rate, large interlayer thermal resistance, and difficult assembly of diamond jet microchannel radiators are solved, providing an efficient and reliable heat dissipation solution for fields such as 5G communication, high-energy lasers, and aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0034] Figure 1 It is a schematic structural diagram of the jet layer of the diamond jet microchannel radiator provided by the embodiment of the present invention;

[0035] Figure 2 It is a schematic structural diagram of the microchannel layer of the diamond jet microchannel radiator provided by the embodiment of the present invention;

[0036] Figure 3 It is an exploded view of the jet layer and the microchannel layer of the diamond jet microchannel radiator provided by the embodiment of the present invention;

[0037] Figure 4 It is a schematic structural diagram of the diamond jet microchannel radiator after the jet layer and the microchannel layer are connected;

[0038] Figure 5 It is a schematic structural diagram of the jet microchannel radiator during operation, connected with a heat source surface and inlet and outlet cooling medium ports. DETAILED DESCRIPTION OF THE INVENTION

[0039] For the purpose of clearly elaborating the objectives, technical solutions, and their advantages of the embodiments of the present invention, this section will, based on the accompanying drawings, provide a detailed and complete explanation of the technical solutions of the embodiments of the present invention. Obviously, the embodiments described herein are only some examples of the present invention, not all of them. All other embodiments that those skilled in the art can obtain without creative efforts based on the disclosed embodiments of the present invention shall be regarded as falling within the scope covered by the present invention.

[0040] A processing method for a diamond jet microchannel heat sink for high heat flux density heat dissipation provided by the present invention belongs to the technical field of heat dissipation for high heat flux density electronic devices. The diamond jet microchannel heat sink is composed of a jet layer and a microchannel layer. This method uses a green diamond laser cutting device and a high-power microscope, with chemically vapor deposited (CVD) diamond as the base material. By precisely controlling the laser power, scanning speed, and number of scans, precise machining of microscale jet holes and microchannels is achieved. The specific steps include equipment and material preparation, laser parameter debugging, heat sink processing, graphite layer removal, and precise hole alignment and assembly. This method can achieve high-precision machining of jet holes and microchannels, effectively remove the residual graphite layer during processing, and meet the heat dissipation performance and reliability requirements of high heat flux density heat sinks. It is applicable to the efficient thermal management of high-power electronic devices such as high-power communication equipment, aerospace electronic systems, and deep underground electronic devices.

[0041] This processing method uses a CVD diamond substrate cleaned by ultrasonic cleaning and undergoes double-sided mechanical polishing as the processing base material. Subsequently, by precisely adjusting key processing parameters such as the power, scanning speed, and number of repeated scans of the laser cutting device, fine control of the sizes of the jet holes and microchannels of the heat sink is achieved. The graphite layer remaining in the jet holes and microchannels is removed by chemical etching. The obtained jet layer and microchannel layer are hole-aligned using thin metal wires, and the jet layer and microchannel layer are connected using epoxy resin + diamond micropowder to fabricate a jet microchannel heat sink. Finally, a gear pump is used to drive the heat transfer fluid circuit, thereby achieving efficient heat dissipation of the diamond heat sink for electronic devices.

[0042] This processing method includes steps S1 - S7:

[0043] S1. Use acetone or alcohol to ultrasonically clean the diamond surface to thoroughly remove contaminants such as grease and dust, and avoid carbonization of impurities during cutting, which may affect the light path.

[0044] S2. Perform double-sided mechanical polishing on the CVD diamond substrate to reduce the surface roughness to Ra ≤ 0.2 μm, so as to improve the uniformity of laser energy absorption and reduce scattering loss.

[0045] S3. Conduct trial processing on the CVD diamond substrate for single holes and single channels, observe the processing results using a high-power microscope, and dynamically adjust processing parameters such as the laser power, scanning speed, and scanning times of the laser equipment to ensure the processing accuracy of the jet holes and microchannels.

[0046] S4. Immerse the processed jet layer and microchannel layer in aqua regia at room temperature for 2 - 3 hours, or immerse the jet layer or microchannel layer in a mixed acid solution to remove the residual graphite layer in the jet layer and microchannel layer.

[0047] S5. Neutralize the waste acidic solution and then place it in a waste liquid pool. Ultrasonically clean the jet layer and microchannel layer in deionized water, and finally dry them in an oven.

[0048] S6. First, mix the epoxy resin matrix and the curing agent in a predetermined ratio, and incorporate a certain amount of diamond powder to form a composite slurry. Subsequently, uniformly coat the epoxy resin - diamond composite slurry in the interface area between the jet layer and the microchannel layer, and at the same time, apply ultraviolet - curable glue at the four corners of the joint surface as an auxiliary adhesive. To ensure the alignment of the interlayer structure, select a metal wire with a diameter smaller than the jet hole diameter to penetrate the two layers from the four corners for mechanical positioning, and then achieve the preliminary fixation of the joint surface through ultraviolet irradiation. Finally, transfer the component to a constant - temperature oven to complete the thermal curing treatment of the epoxy resin system, and finally obtain a jet microchannel heat sink with both high bonding strength and excellent thermal conductivity.

[0049] S7. Place the assembled jet microchannel heat sink in a packaging device, connect a gear pump to drive the fluid for a sealing test to ensure no leakage and sufficient mechanical strength.

[0050] The following further explains the embodiments of the present invention in conjunction with the accompanying drawings:

[0051] Select a CVD diamond substrate with a thickness of 2 mm (size 10 mm × 10 mm), ultrasonically clean it with acetone for 10 minutes, and dry it with a lint - free cloth.

[0052] Perform a double - sided mechanical polishing process using a diamond polishing machine and a cast - iron grinding disc. Prepare a diamond grinding paste with an appropriate concentration by mixing olive oil and diamond powder, and evenly apply it on the surface of the cast - iron disc. Subsequently, carry out the polishing operation at a speed of 2500 rpm, and finally achieve a surface roughness of Ra ≤ 0.2 μm for the CVD diamond, and the thickness uniformity is controlled within ± 1%.

[0053] The edge of chemical vapor deposition (CVD) diamond was trial processed by laser cutting technology to form a tapered hole. In the experiment, a tapered jet hole was processed, with an upper hole diameter of 0.5 mm, a lower hole diameter of 0.2 mm, and a depth of 2 mm. The initial laser processing parameters were set as a power of 12 W, a scanning speed of 20 mm / s, and a scanning number of 40 times. The actual jet hole diameter was measured using a 20-fold microscope, and the results showed that the upper hole diameter was 0.5 mm, the lower hole diameter was 0.11 mm, and the depth was 2 mm. By dynamically adjusting the processing parameters, when the laser processing parameters were adjusted to a power of 10 W, a scanning speed of 10 mm / s, and the scanning number increased to 60 times, a tapered jet hole with an upper hole diameter of 0.5 mm, a lower hole diameter of 0.2 mm, and a depth of 2 mm was successfully processed.

[0054] Using computer-aided design CAD technology, draw the drawing of the 6×14 array holes of the jet layer, and import this drawing into the laser cutting equipment. By setting the laser processing parameters obtained above, the Figure 1 processing effect shown can be achieved. Figure 1 Figure 7 is a schematic structural diagram of the jet layer of the diamond jet microchannel radiator provided by the embodiment of the present invention.

[0055] The edge of chemical vapor deposition (CVD) diamond was trial processed by laser cutting technology to form a microchannel. According to the trial processing results observed by the microscope, by dynamically adjusting the processing parameters, when the laser processing parameters were adjusted to a power of 10 W, a scanning speed of 20 mm / s, and the scanning number increased to 80 times, a microchannel with a depth of 1 mm and a width of 0.3 mm was successfully processed.

[0056] Using computer-aided design (CAD) technology, draw the microchannel drawing, and import the completed drawing into the laser cutting equipment. By setting appropriate laser processing parameters, the Figure 2 microchannel structure shown can be achieved. Figure 2 Figure 17 is a schematic structural diagram of the microchannel layer of the diamond jet microchannel radiator provided by the embodiment of the present invention.

[0057] Immerse the processed jet layer and microchannel layer in aqua regia and treat them at room temperature for 2 hours. After treatment, the carbon content on the surface of the jet hole and microchannel is ≤5%.

[0058] Prepare an epoxy resin-diamond micropowder composite slurry, with a mass ratio of epoxy resin to curing agent of 6:1 and an addition amount of diamond micropowder of 5 wt%.

[0059] Use a Φ0.08 mm piano wire to position the four corners of the jet hole (deviation ≤±0.03 mm). After coating the composite slurry, apply ultraviolet light curing glue by dotting (curing time 45 seconds).

[0060] After ultraviolet pre-curing, it is transferred to an oven for step curing (80°C / 2h + 120°C / 1h), and the interfacial thermal resistance test is 0.09 cm 2 ·K / W, obtaining the jet microchannel heat exchanger as shown in Figures 3-4 . Figure 3 is the exploded view of the jet layer and the microchannel layer of the diamond jet microchannel radiator provided by the embodiment of the present invention; Figure 4 is the structural schematic diagram of the jet layer and the microchannel layer of the diamond jet microchannel radiator after connection provided by the embodiment of the present invention.

[0061] The assembled radiator drives the deionized water circulation system through a gear pump, and its test pressure reaches 1 MPa, and the leakage rate does not exceed 5×10 -7 Pa·m 3 / s.

[0062] As shown in Figure 5 , Figure 5 is the structural schematic diagram of the jet microchannel radiator during operation connected with a heat source surface and inlet and outlet cooling medium ports. Under the experimental conditions of a heat flux density of 400 W / cm 2 , the inlet flow rate is maintained at 4 ml / s, the thermal resistance of the radiator is 0.103 cm 2 ·K / W, and at the same time, there is a pressure loss of 2796 Pa. The inlet temperature of the cooling medium is set at 25°C, and the outlet temperature reaches 49.9°C.

[0063] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A method for processing a diamond jet microchannel heat sink for high heat flux density heat dissipation, characterized in that: include: Use acetone or alcohol to ultrasonically clean the surface of the CVD diamond substrate to completely remove contaminants and avoid carbonization of impurities that affect the optical path during cutting; Double-sided mechanical polishing of the CVD diamond substrate was performed to reduce the surface roughness to Ra≤0.2μm to improve the uniformity of laser energy absorption and reduce scattering losses; Conduct trial processing of single hole and single channel on CVD diamond substrate, observe the processing results with a high-power microscope, and dynamically adjust processing parameters such as laser power, scanning speed and scanning times of laser equipment to ensure the processing accuracy of jet holes and microchannels; Soak the processed jet layer and microchannel layer in aqua regia at room temperature for 2-3 hours, or soak the jet layer or microchannel layer in other strong acidic solutions for a period of time, so as to remove the residual graphite layer in the jet layer and microchannel layer; The waste acid solution is neutralized and placed in a waste liquid pool, the jet layer and the microchannel layer are placed in deionized water for ultrasonic cleaning, and finally placed in a drying oven for drying; First, the epoxy resin matrix and the curing agent are mixed in a predetermined ratio, and a certain amount of diamond powder is added to form a composite slurry; then, the epoxy resin-diamond composite slurry is evenly coated on the interface area between the jet layer and the microchannel layer, and at the same time, UV curing glue is spot-coated on the four corners of the joint surface as an auxiliary adhesive; to ensure the alignment of the interlayer structure, metal wires with a diameter smaller than the jet channel are selected to penetrate the two layers from the four corners for mechanical positioning, and then the preliminary fixation of the joint surface is achieved by ultraviolet light irradiation; finally, the component is transferred to a constant temperature oven to complete the thermal curing treatment of the epoxy resin system, and finally a jet microchannel heat sink with high bonding strength and excellent thermal conductivity is obtained; The assembled jet microchannel heat sink is placed in a packaging device and connected to a gear pump to drive the fluid for a sealing test to ensure no leakage and sufficient mechanical strength.

2. The processing method according to claim 1, characterized in that: The jet layer and the microchannel layer of the jet microchannel heat sink are both made of CVD diamond material, and the thickness of the jet layer and the microchannel layer are both in the range of 2-4 mm.

3. The processing method according to claim 1, characterized in that: The jet microchannel radiator comprises a jet layer and a microchannel layer. The jet holes of the jet layer are conical, and the microchannels of the microchannel layer are rectangular.

4. The processing method according to claim 1, characterized in that: The surface thickness uniformity of the jet microchannel heat sink is within ±1%.

5. The processing method according to claim 1, characterized in that: The trial processing of a single hole and a single channel on the CVD diamond substrate is performed, the processing results are observed using a high-power microscope, and the processing parameters such as the laser power, scanning speed and scanning times of the laser equipment are dynamically adjusted to ensure the processing accuracy of the jet hole and the microchannel, including: The microchannel depth of the microchannel layer was adjusted to within ±8 μm, and the jet hole size was adjusted to within ±3 μm.

6. The processing method according to claim 1, characterized in that: The process of soaking the processed fluidic layer and microchannel layer in aqua regia for 2-3 hours at room temperature, or soaking the fluidic layer or microchannel layer in other strong acidic solutions for a period of time, thereby removing the residual graphite layer in the fluidic layer and microchannel layer, comprises: The carbon contents of the jet holes of the jet layer and the microchannel surface of the microchannel layer after the aqua regia corrosion treatment are adjusted to be within ≤5%.

7. The processing method according to claim 1, characterized in that: The predetermined ratio is that the mass ratio of the epoxy resin matrix to the curing agent is 6:1, and the addition amount of the quantitative diamond powder is 5wt%.

8. The processing method according to claim 1, characterized in that: The diameter of the metal wire is in the range of 0.05-0.9 mm, the material is piano wire or stainless steel wire, and the hole accuracy deviation is ≤±5μm.

9. The processing method according to claim 1, characterized in that: The curing time of the UV curing adhesive is in the range of 30-60 seconds, and the thermal curing condition of the epoxy resin system is 60° C. / 2h.

10. The processing method according to claim 1, characterized in that: The sealing test pressure range of the jet microchannel radiator is 0.5-1MPa, and the leakage rate is ≤1×10-6Pa·m 3 / s; The inlet diameter of the conical structure of the jet hole is in the range of 0.2-0.5 mm, and the outlet diameter is in the range of 0.1-0.3 mm, and the inlet diameter of the conical structure is always larger than the outlet diameter; the rectangular cross-section width of the microchannel of the microchannel layer is in the range of 0.3-0.5 mm, and the depth is in the range of 0.3-1.7 mm; The overall size of the jet microchannel heat sink is 10mm×10mm×4mm, which is suitable for high heat flux density heat dissipation scenarios such as high-power communication equipment, high-power lasers and aerospace electronic equipment.

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