Gradient diamond / copper radiating fin and manufacturing method

Abstract

The gradient diamond / copper cooling fin comprises a cooling fin structural part, a filling groove is formed in the top of the cooling fin structural part, and a first heat conduction layer, a second heat conduction layer, a third heat conduction layer and a fourth heat conduction layer are sequentially arranged in the filling groove from bottom to top. The manufacturing method comprises the following steps: 1) diamond differential coating; 2) laying a heat conduction layer; 3) sintering; and 4) finish machining of the sintered body. Compared with the prior art, the method has the advantages that a high-efficiency heat conduction path from a high-heat-flux chip to a structural part is realized, the interface thermal resistance is effectively reduced, and the thermal diffusivity is enhanced; the wettability and the bonding property of a diamond and copper interface are improved; the sintering process of the material is quicker and more efficient, the process is simple, the complexity in the preparation process is reduced, and the processing time and energy consumption are reduced; the heat conduction requirement from the chip to the heat dissipation piece is met, the mechanical property and the heat resistance of the structural piece are comprehensively balanced while the high heat conductivity is maintained, and the overall material quality and the product performance are improved.

Description

Technical Field

[0001] The invention relates to the technical field of copper-based composite material preparation, in particular to a gradient diamond / copper heat sink and a manufacturing method thereof. Background Art

[0002] Cold plate liquid cooling technology was developed earlier. Currently, cold plate liquid cooling data center products account for a high proportion in the market. In 2019, cold plate liquid cooling products and immersion liquid cooling products accounted for 82% and 18% of the market respectively. Immersion liquid cooling is a direct contact cooling method. Compared with cold plate liquid cooling, it makes greater use of the specific heat capacity of liquid, has higher cooling efficiency, and can effectively reduce the PUE of data centers. At present, the main problems facing liquid cooling technology are concentrated on the poor consistency of heat transfer and heat dissipation of key heat dissipation components in the system, which leads to slow heat dissipation of the liquid cooling system and the decline of server computing power. The consistency of heat dissipation between components of the liquid cooling system and the development of efficient heat dissipation materials are the first difficulties to be overcome for the stable operation of high-computing power servers. Since 2010, with the development of data centers towards larger scale and integration, the bottleneck of air cooling has once again become prominent, posing a higher challenge to the demand for heat dissipation of high-power and high-energy-consuming electronic chips. Based on this, a research boom in immersion liquid cooling technology in high-power electronic device industries such as data centers has been officially launched.

[0003] In 2010, Sugon took the lead in exploring server liquid cooling technology in China, and in 2013, Sugon completed the verification of the first immersion liquid cooling principle machine. Since 2016, the development of immersion liquid cooling in domestic data centers has made rapid progress. As a pioneer in liquid cooling in domestic data centers, Sugon has started research on the large-scale application of immersion liquid cooling servers. In 2017, Sugon delivered China's first commercial phase-change immersion liquid cooling server - Liquid inside, with a power usage efficiency PUE as low as 1.01 to 1.02. In 2019, Sugon completed the first large-scale application project of phase-change immersion liquid cooling server in China, "Silicon Cube", which mainly uses the phase change latent heat of low-boiling-point working fluid to remove the heat generated by the server, greatly improving the heat dissipation performance of the system. This is a major breakthrough in the field of immersion liquid cooling in data centers.

[0004] The heat sink is a key core component of a liquid-cooled server. It must have good thermal conductivity and heat dissipation capabilities as well as fast heat exchange performance with the liquid medium. At present, there are still the following problems with heat sinks: First, traditional heat sinks often use aluminum or copper as materials. Although their thermal conductivity is high, it is still insufficient to cope with the large amount of heat generated by high-performance servers, and the thermal conductivity of a single material is easy to reach its limit under long-term high-power operation conditions, making it difficult to further improve the heat exchange efficiency. Second, although materials with high thermal conductivity (such as graphene and carbon nanotubes) have excellent performance, they are usually expensive and face technical bottlenecks in processing and large-scale production. Third, the production of high-precision heat sinks requires precision processing technology (such as CNC processing or laser cutting), which has high manufacturing costs and long preparation time. Fourth, the contact interface between the heat sink surface and the heat source usually has microscopic unevenness, which leads to increased thermal resistance. The current interface material (TIM) has not completely solved this problem, affecting the overall heat conduction efficiency. Fifth, complex heat sink structure designs (such as microchannel structures) are difficult to achieve in batches in actual manufacturing, and have high requirements for material performance. Although some new 3D printing technologies can manufacture complex structures, they still face problems such as high cost and slow speed. Sixth, the existing heat sink designs are mostly flat or simple fin-type, which cannot fully utilize three-dimensional space for heat exchange, and the anisotropic thermal conductivity of the material leads to uneven heat distribution, which easily forms local hot spots and affects chip performance and life.

[0005] According to statistics, relevant scholars' research on the performance improvement of heat sink materials is mainly focused on thermal conduction, structural special-shaped design, composite material design, and preparation methods. How to further improve the heat transfer and heat dissipation performance of heat sink materials and develop a gradient structure diamond copper heat dissipation material to meet the stable and high-reliability use of higher-power chips in immersion liquid cooling servers is the primary problem to be overcome for the stable operation of high-computing power / power servers. Summary of the invention

[0006] The purpose of the present invention is to provide a gradient diamond / copper heat sink and a manufacturing method, aiming to solve the problems of insufficient heat dissipation capacity, large interface thermal resistance, complex preparation process and high cost of existing heat dissipation materials in high-power electronic components.

[0007] In order to solve the above technical problems, the technical solution provided by the present invention is as follows: a gradient diamond / copper heat sink, comprising a heat sink structure, wherein the heat sink structure comprises a copper substrate, wherein the copper substrate is a rectangular parallelepiped structure, wherein a filling groove is provided on the top of the copper substrate, wherein a first heat conducting layer, a second heat conducting layer, a third heat conducting layer, and a fourth heat conducting layer are sequentially provided in the filling groove from bottom to top;

[0008] The first heat-conducting layer is a large-particle diamond powder with double coatings of Ti and Cu;

[0009] The second heat-conducting layer is a Ti-plated large-particle diamond powder;

[0010] The third heat-conducting layer is a fine-grained diamond powder plated with a Ti layer;

[0011] The fourth heat-conducting layer is fine-grained diamond powder with double layers of Ti and Cu plating;

[0012] The top of the fourth heat conducting layer is flush with the filling groove.

[0013] As a preferred solution, the differential particle size of the large diamond particles in the first heat-conducting layer and the second heat-conducting layer is 190 μm-260 μm.

[0014] As a preferred solution, the particle size of the fine-grained diamond powder in the third heat-conducting layer and the fourth heat-conducting layer is 30 μm-50 μm.

[0015] As a preferred solution, the thickness of the first heat-conducting layer is 1-3 mm.

[0016] As a preferred solution, the thickness of the second heat-conducting layer is 3-5 mm.

[0017] As a preferred solution, the thickness of the third heat-conducting layer is 2-4 mm.

[0018] As a preferred solution, the thickness of the fourth heat-conducting layer is 0.5-1 mm.

[0019] A method for manufacturing a gradient diamond / copper heat sink comprises the following steps:

[0020] 1) Diamond differential coating: The volume percentage of diamond / copper is 33-50:67-50. Diamond micropowders of two particle sizes are subjected to Ti and Cu plating processes. Diamond micropowders are plated with Ti by vacuum ion plating. Pure Ti rod targets are selected. The target diameter is 30-40 mm. High-energy particles are generated by arc discharge to bombard the Ti rods, so that Ti is deposited on the surface of the diamond micropowder. The thickness of the Ti film is 0.2-0.3 μm. The diamond micropowders of two particle sizes plated with Ti are then plated with Cu by magnetron sputtering, and the coating thickness is 20-100 nm.

[0021] 2) Laying the thermal conductive layer: Lay a layer of Ti-plated and Cu-plated large-grained diamond powder on the lowest end of the copper structure; Lay a layer of Ti-plated large-grained diamond powder on the upper end; Lay a layer of Ti-plated fine-grained diamond powder on the upper end; Lay a layer of Ti-plated and Cu-plated fine-grained diamond powder on the upper end;

[0022] 3) Sintering: Place the copper structure and the 4 layers of gradient diamond / copper powder thermal conductive layer in a spark plasma sintering furnace for sintering, and then keep warm;

[0023] 4) Sintered body finishing: Make the top heat-conducting layer of double-coated fine-grained diamond powder fit with the heat-generating components to reduce the thermal resistance between interfaces, increase the heat transfer channel, and improve the heat transfer efficiency.

[0024] As a preferred solution, in step 3), the sintering pressure is 40-50 MPa, the sintering temperature is 850-950° C., and the holding time is 15-25 min.

[0025] The advantages of the present invention compared with the prior art are:

[0026] 1. Efficient heat conduction path: Through the gradient structure design of diamond and copper, an efficient heat conduction path from high heat flux density chips to structural parts is achieved, which effectively reduces the interface thermal resistance, enhances the heat diffusion capacity, and significantly improves the heat dissipation efficiency in high computing power / high power servers.

[0027] 2. Interface wettability and bonding: The wettability and bonding of the diamond-copper interface are improved through vacuum ion plating Ti and magnetron sputtering Cu plating technology. The Ti and Cu plating layers protect the diamond surface and reduce the risk of oxidation or degradation of the diamond surface.

[0028] 3. Simple and efficient process: By introducing the spark plasma sintering (SPS) process and combining it with gradient powder laying technology, the sintering process of the material is faster and more efficient, the process is simpler, the complexity of the preparation process is reduced, the processing time and energy consumption are reduced, and the production cost is reduced.

[0029] 4. Improved overall performance: Through the diamond / copper layered gradient design, diamond powders of different particle sizes and double-layer materials optimize the thermal conductivity distribution to meet the heat conduction requirements from the chip to the heat sink. While maintaining high thermal conductivity, the mechanical properties and heat resistance of the structural parts are comprehensively balanced, improving the overall material quality and product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of large particles and fine crystals of double-coated diamond micropowder of the present invention;

[0031] Figure 2 It is a layered gradient structure diagram of the present invention;

[0032] Figure 3 It is a top view of the heat sink structure of the present invention.

[0033] As shown in the figure: 1. Large particle / fine crystal diamond powder, 2. Ti plating layer, 3. Cu plating layer, 4. Fourth thermal conductive layer, 5. Third thermal conductive layer, 6. Second thermal conductive layer, 7. First thermal conductive layer, 8. Heat sink structure. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of the embodiments of the present invention, "plurality" means at least 2.

[0038] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] A gradient diamond / copper heat sink, comprising a heat sink structure 8, the heat sink structure comprising a copper substrate, the copper substrate is a rectangular parallelepiped structure, a filling groove is provided on the top of the copper substrate, and a first heat conducting layer 7, a second heat conducting layer 6, a third heat conducting layer 5, and a fourth heat conducting layer 4 are sequentially provided in the filling groove from bottom to top;

[0040] The first heat-conducting layer is a large-particle diamond powder with double coatings of Ti and Cu;

[0041] The second heat-conducting layer is a Ti-plated large-particle diamond powder;

[0042] The third heat-conducting layer is a fine-grained diamond powder plated with a Ti layer;

[0043] The fourth heat-conducting layer is fine-grained diamond powder with double layers of Ti and Cu plating;

[0044] The top of the fourth heat conducting layer is flush with the filling groove.

[0045] The present invention provides a diamond double-plated layered powder structure and a method for preparing a diamond / copper gradient material by a spark plasma sintering process, the purpose of which is to solve the problems of insufficient heat transfer and heat dissipation capacity of existing heat dissipation materials on high computing power / power servers, large material interface thermal resistance, complex preparation process and high cost.

[0046] The present invention is achieved through the following technical solutions:

[0047] (1) Diamond / copper volume percentage 33-50:67-50. Diamond micropowders of two particle sizes are plated with Ti and Cu. Diamond micropowders are plated with Ti by vacuum ion plating, using pure Ti rod targets with a target size of 30-40 mm in diameter. High-energy particles are generated by arc discharge to bombard the Ti rods, so that Ti is deposited on the surface of the diamond micropowders. The thickness of the Ti film is 0.2-0.3 μm. The diamond micropowders of two particle sizes that have been plated with Ti are then plated with Cu by magnetron sputtering, and the thickness of the coating is about 20-100 nm.

[0048] (2) Spreading a layer of Ti-plated and Cu-plated large-grained diamond powder on the lowest end of the copper structure, i.e., the first thermal conductive layer, with a thickness of 1-3 mm; spreading a layer of Ti-plated large-grained diamond powder on the upper end, i.e., the second thermal conductive layer, with a thickness of 3-5 mm; spreading a layer of Ti-plated fine-grained diamond powder on the upper end, i.e., the third thermal conductive layer, with a thickness of 2-4 mm; spreading a layer of Ti-plated and Cu-plated fine-grained diamond powder on the upper end, i.e., the fourth thermal conductive layer, with a thickness of 0.5-1 mm;

[0049] The third thermal conductive layer 5 and the second thermal conductive layer 6 are respectively fine-grained diamond powder of the Ti-plated layer and large-grained diamond powder of the Ti-plated layer. The first thermal conductive layer 7 is large-grained diamond powder of double-plated Ti and Cu. The Cu-plated layer on the outside of the double-plated layer can better integrate with the copper of the heat sink structure 8 to form a more complete interface relationship. At the same time, the Cu-plated layer at the first thermal conductive layer 7 and the Ti-plated layer at the second thermal conductive layer 6 have good wettability and maintain a good interface relationship. The double-plated diamond at the fourth thermal conductive layer 4 is in direct contact with the high-power server chip heating components after assembly, and the outer Cu-plated layer has a higher heat transfer ratio with the chip heating components.

[0050] (3) Then, the structural member 8 and the laid 4 layers of gradient diamond / copper powder are placed in a spark plasma sintering furnace for sintering at a temperature of 850-950° C. for 20±5 min under a sintering pressure of 40-50 MPa;

[0051] (4) The sintered body is finely processed to make the double-layered fine-grained diamond powder of the fourth heat-conducting layer 4 fit the heat-generating components, thereby reducing the thermal resistance between interfaces, increasing the heat transfer channel, and improving the heat transfer efficiency.

[0052] Among them, the particle sizes of the two types of diamond powder are 190μm-260μm and 30μm-50μm; the process parameters of vacuum ion plating Ti are: the vacuum chamber must reach 5×10-5Pa before starting work, the working vacuum must meet the requirements: between 1×10-3 and 5×10-3Pa, the diamond powder must be preheated to 300℃ (too low temperature will lead to insufficient coating adhesion, too high temperature may damage the diamond surface structure), set the target power DC power: 100-300W, substrate bias: -50 to -20 0V, deposition rate: 14-17nm / min, deposition time 15min; target power DC power set for Cu plating: 100W, deposition rate: 11-12nm / min, deposition time 2-8min; after SPS sintering, the structure 5 powder spreading position is sintered to form a gradient diamond / copper composite material, from bottom to top: Ti-plated and Cu-plated double-layer large-grained diamond / copper layer, Ti-plated large-grained diamond / copper layer, Ti-plated fine-grained diamond / copper layer, Ti-plated and Cu-plated double-layer fine-grained diamond / copper layer.

[0053] The thermal diffusion coefficient of the diamond / copper layered gradient material prepared by the above layered gradient powder + spark plasma sintering process has been greatly improved, and the thermal conductivity and heat dissipation capacity of the structural parts have also been significantly improved, effectively solving the deficiencies of traditional diamond / copper composite materials in heat dissipation and mechanical properties, and providing a more reliable solution for high-computing power server heat dissipation technology.

[0054] Example 1

[0055] Diamond powder coating:

[0056] Large-grained diamond powder with a particle size of 190 μm-260 μm and fine-grained diamond powder with a particle size of 30 μm-50 μm are selected.

[0057] Diamond micropowders with two particle sizes were vacuum ion plated with Ti, and the thickness of the Ti film was 0.2-0.3 μm.

[0058] The diamond powder after Ti plating is subjected to Cu plating by magnetron sputtering, and the thickness of the Cu plating layer is 20-100nm.

[0059] Laying the thermal conductive layer:

[0060] Large-grained diamond micropowder with double coatings of Ti and Cu is laid on the bottom of the filling groove of the copper substrate, with a thickness of 1-3 mm.

[0061] The Ti-plated large-particle diamond powder is laid on the double-plated large-particle diamond powder, with a thickness of 3-5 mm.

[0062] The fine-grained diamond powder of the Ti-plated layer is laid on the large-grained diamond powder of the Ti-plated layer, with a thickness of 2-4 mm.

[0063] The top layer is covered with fine-grained diamond powder with double coatings of Ti and Cu, with a thickness of 0.5-1 mm.

[0064] sintering:

[0065] The laid copper substrate and the gradient diamond / copper powder heat-conducting layer are placed in a spark plasma sintering furnace and kept at a temperature of 850-950° C. for 20 minutes under a pressure of 40-50 MPa.

[0066] Sintered body finishing:

[0067] The sintered body is finely processed after sintering so that the top double-layer fine-grained diamond powder can be assembled and fitted with the heat-generating components to reduce the thermal resistance between interfaces, increase the heat transfer channel, and improve the heat transfer efficiency.

[0068] Example 2

[0069] Diamond powder coating:

[0070] Large-grained diamond powder with a particle size of 200μm-250μm and fine-grained diamond powder with a particle size of 35μm-45μm are selected.

[0071] Diamond micropowders with two particle sizes were vacuum ion plated with Ti, and the thickness of the Ti film was 0.25 μm.

[0072] The diamond powder after Ti plating is subjected to Cu plating by magnetron sputtering, and the thickness of the Cu plating layer is 50 nm.

[0073] Laying the thermal conductive layer:

[0074] Large-grained diamond powder with double coatings of Ti and Cu is laid at the bottom of the filling groove of the copper substrate with a thickness of 2 mm.

[0075] The Ti-plated large-grained diamond powder is laid on the double-plated large-grained diamond powder, with a thickness of 4 mm.

[0076] The fine-grained diamond powder of the Ti-plated layer is laid on the large-grained diamond powder of the Ti-plated layer, with a thickness of 3 mm.

[0077] The top layer is paved with fine-grained diamond powder with double layers of Ti and Cu, with a thickness of 0.8 mm.

[0078] sintering:

[0079] The laid copper substrate and the gradient diamond / copper powder thermal conductive layer were placed in a spark plasma sintering furnace and kept at 900° C. for 18 minutes under a pressure of 45 MPa.

[0080] Sintered body finishing:

[0081] The sintered body is finely processed after sintering so that the top double-layer fine-grained diamond powder can be assembled and fitted with the heat-generating components to reduce the thermal resistance between interfaces, increase the heat transfer channel, and improve the heat transfer efficiency.

[0082] Table 1 shows the indexes of SPS-prepared diamond / copper layered gradient materials and traditional diamond / copper materials

[0083]

[0084] Table 1

[0085] The present invention provides a method for preparing diamond / copper thermal conductive materials by diamond double coating + spark plasma sintering (SPS) process, which belongs to the technical field of copper-based composite material preparation. The method solves the key problems of high heat generation, low heat transfer and heat dissipation efficiency, and insufficient mechanical properties of traditional thermal conductive materials in large high-power electronic components, and effectively improves the service performance and service life of the materials.

[0086] The present invention and its embodiments are described above. Such description is not restrictive. The structures and material ratios in the embodiments are only part of the embodiments of the present invention and are only used to explain the specific implementation process of the present invention. All other embodiments obtained based on the concept of the present invention are within the protection scope of the present invention.

Claims

1. A gradient diamond / copper heat sink, characterized in that: The heat sink structure comprises a copper substrate, the copper substrate is a rectangular parallelepiped structure, a filling groove is provided on the top of the copper substrate, and a first heat conducting layer, a second heat conducting layer, a third heat conducting layer, and a fourth heat conducting layer are sequentially provided in the filling groove from bottom to top; The first heat-conducting layer is a large-particle diamond powder with double coatings of Ti and Cu; The second heat-conducting layer is a Ti-plated large-particle diamond powder; The third heat-conducting layer is a fine-grained diamond powder plated with a Ti layer; The fourth heat-conducting layer is fine-grained diamond powder with double layers of Ti and Cu plating; The top of the fourth heat conducting layer is flush with the filling groove.

2. A gradient diamond / copper heat sink according to claim 1, characterized in that: The differential particle size of the large diamond particles in the first heat-conducting layer and the second heat-conducting layer is 190 μm-260 μm.

3. The gradient diamond / copper heat sink according to claim 1, characterized in that: The particle size of the fine-grained diamond powder in the third heat-conducting layer and the fourth heat-conducting layer is 30 μm-50 μm.

4. The gradient diamond / copper heat sink according to claim 1, characterized in that: The thickness of the first heat-conducting layer is 1-3 mm.

5. The gradient diamond / copper heat sink according to claim 1, characterized in that: The thickness of the second heat-conducting layer is 3-5 mm.

6. The gradient diamond / copper heat sink according to claim 1, characterized in that: The thickness of the third heat-conducting layer is 2-4 mm.

7. The gradient diamond / copper heat sink according to claim 1, characterized in that: The thickness of the fourth heat-conducting layer is 0.5-1 mm.

8. A method for manufacturing a gradient diamond / copper heat sink, characterized in that: The specific steps include: 1) Diamond differential coating: The volume percentage of diamond / copper is 33-50:67-50. Diamond micropowders of two particle sizes are subjected to Ti and Cu plating processes. Diamond micropowders are plated with Ti by vacuum ion plating. Pure Ti rod targets are selected. The target diameter is 30-40 mm. High-energy particles are generated by arc discharge to bombard the Ti rods, so that Ti is deposited on the surface of the diamond micropowder. The thickness of the Ti film is 0.2-0.3 μm. The diamond micropowders of two particle sizes plated with Ti are then plated with Cu by magnetron sputtering, and the coating thickness is 20-100 nm. 2) Laying the thermal conductive layer: Lay a layer of Ti-plated and Cu-plated large-grained diamond powder on the lowest end of the copper structure; Lay a layer of Ti-plated large-grained diamond powder on the upper end; Lay a layer of Ti-plated fine-grained diamond powder on the upper end; Lay a layer of Ti-plated and Cu-plated fine-grained diamond powder on the upper end; 3) Sintering: Place the copper structure and the 4 layers of gradient diamond / copper powder thermal conductive layer in a spark plasma sintering furnace for sintering, and then keep warm; 4) Sintered body finishing: Make the top heat-conducting layer of double-coated fine-grained diamond powder fit with the heat-generating components to reduce the thermal resistance between interfaces, increase the heat transfer channel, and improve the heat transfer efficiency.

9. The method for manufacturing a gradient diamond / copper heat sink according to claim 8, characterized in that: In the step 3), the sintering pressure is 40-50 MPa, the sintering temperature is 850-950° C., and the holding time is 15-25 min.

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