Diamond / aluminum composite material, method for preparing the same, and use thereof

Abstract

The application relates to a diamond / aluminum composite material and a preparation method and application thereof. The preparation method of the diamond / aluminum composite material comprises the following steps: preparing diamond particles into a preform; placing the preform into a composite mold, pouring aluminum liquid on the preform; vacuumizing and applying pressure on the aluminum liquid in a mechanical pressurizing mode, so that the aluminum liquid infiltrates into the diamond particles; and cooling. The preparation method of the diamond / aluminum composite material is simple in operation and low in cost, and can further improve the performance of the diamond / aluminum composite material, especially the heat conduction performance.

Description

Technical Field

[0001] This application relates to the field of electronic packaging materials technology, and in particular to a diamond / aluminum composite material, its preparation method, and its application. Background Technology

[0002] As electronic devices become increasingly miniaturized, lightweight, and highly integrated, their power consumption is also rapidly increasing. Existing thermal management materials are finding it increasingly difficult to meet heat dissipation requirements. To ensure the lifespan and reliability of power semiconductor devices, there is an urgent need to develop thermal management materials with superior comprehensive performance. Diamond / aluminum composite materials possess advantages such as ultra-high thermal conductivity, adjustable coefficient of thermal expansion, and low density, making them suitable for use as electronic packaging substrate materials and heat sink materials. They can effectively meet the heat dissipation requirements of high-power devices and have broad application prospects in aerospace, rail transportation, and microwave communications. However, due to the lack of mature manufacturing processes, industrial-scale production and application are not yet feasible.

[0003] Harmful interfacial reactions are a significant factor hindering the further development of diamond / aluminum composites. Harmful interfacial reactions refer to the chemical reaction between diamond and molten aluminum at the interface, forming a brittle and hygroscopic Al4C3 phase. The Al4C3 phase is prone to hydrolysis in humid environments, leading to interfacial debonding, increased interfacial thermal resistance, and decreased thermal conductivity in diamond / aluminum composites. For example, in alternating working environments, thermal expansion in diamond / aluminum composites can cause interfacial debonding between diamond and aluminum, resulting in increased interfacial thermal resistance and reduced thermal conductivity of the composite material. Summary of the Invention

[0004] Based on this, this application provides a diamond / aluminum composite material, its preparation method, and its application, which can effectively reduce harmful interfacial reactions and thus improve the thermal conductivity of the diamond / aluminum composite material.

[0005] In a first aspect, this application provides a method for preparing a diamond / aluminum composite material, characterized by comprising the following steps:

[0006] Diamond particles are made into preforms;

[0007] The preform is placed in a composite mold, and molten aluminum is poured onto the preform.

[0008] Vacuuming and applying pressure to the molten aluminum using mechanical pressurization to allow the molten aluminum to penetrate the diamond particles; and cooling.

[0009] In some embodiments, the mechanical supercharging includes increasing the pressure to a preset pressure value within a predetermined time and holding the pressure at the preset pressure value, wherein the mechanical supercharging satisfies at least one of the following features (1) to (3):

[0010] (1) The preset pressure value of the mechanical supercharger is 1MPa to 40MPa;

[0011] (2) The pressure holding time of the mechanical supercharging is 1 min to 60 min;

[0012] (3) The boosting time of the mechanical supercharger is 0.1 min to 5 min.

[0013] In some embodiments, the vacuuming step results in a relative vacuum of -50 kPa to 0 kPa.

[0014] In some embodiments, the temperature of the molten aluminum is 710°C to 860°C.

[0015] In some embodiments, prior to the steps of placing the preform in the composite mold and pouring molten aluminum onto the preform, a step of preheating the preform is included.

[0016] The preheating process includes heating the preform to a preset temperature value and holding it at the preset temperature value, wherein the preheating process satisfies at least one of the following features (4) to (6):

[0017] (4) The preset temperature value of the preheating treatment is 500℃~750℃;

[0018] (5) The heat preservation time of the preheating treatment is 10 min to 90 min;

[0019] (6) The heating rate of the preheating treatment is 2℃ / min to 20℃ / min.

[0020] In some embodiments, the cooling is either along with the composite mold or air cooling.

[0021] In some embodiments, the diamond particles have a particle size of 45 micrometers to 500 micrometers, and may be 180 micrometers to 212 micrometers.

[0022] In some embodiments, the diamond particles are single-crystal diamonds.

[0023] In some embodiments, the molten aluminum is obtained by refining aluminum-containing metal materials, including pure aluminum and / or aluminum alloys.

[0024] In some embodiments, the aluminum alloy includes one or more of Al-Si alloy, Al-Si-Cu alloy, Al-Si-Mg alloy, Al-Cu alloy, Al-Mg alloy, Al-Cu-Mg alloy, Al-Zn-Cu alloy, Al-Zn-Mg-Cu alloy, and Al-Si-Cu-Mg alloy.

[0025] In some embodiments, the preform is prepared using a near-net-shape forming mold.

[0026] In a second aspect, this application provides a diamond / aluminum composite material prepared by the aforementioned method for preparing diamond / aluminum composite materials.

[0027] A third aspect of this application provides the application of the aforementioned diamond / aluminum composite material in the preparation of electronic packaging products or heat sink products.

[0028] Compared with the prior art, this application has at least the following beneficial effects:

[0029] The method for preparing diamond / aluminum composite materials provided in this application employs a combination of vacuum extraction and mechanical pressurization. This allows molten aluminum to penetrate diamond particles in a very short time, avoiding prolonged contact between diamond and aluminum under high temperature or high pressure conditions. This reduces the probability of harmful interfacial reactions and decreases the formation of the Al4C3 phase, thereby improving the thermal conductivity and stability of the diamond / aluminum composite material. Furthermore, the method for preparing diamond / aluminum composite materials provided in this application has the advantages of simple operation and low cost. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 A schematic flowchart illustrating a method for preparing a diamond / aluminum composite material according to an embodiment of this application;

[0032] Figure 2 A schematic flowchart of a method for preparing a diamond / aluminum composite material according to another embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the structure of a composite mold according to one embodiment of this application;

[0034] Figure 4 These are scanning electron microscope (SEM) images of the morphology of diamond / aluminum composite materials in different embodiments of this application.

[0035] Figure 5 These are microscopic morphology images of diamond / aluminum composite materials in different embodiments of this application.

[0036] Explanation of reference numerals in the attached figures:

[0037] 7. Base; 8. Vacuum pipe; 9. Demolding top plate; 10. Cold salt; 11. Molten aluminum; 12. Pressure head; 13. Graphite felt; 14. Mold; 15. Preform; 16. Exhaust channel; 17. Sealing ring; 18. Hydraulic ejection rod. Detailed Implementation

[0038] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0039] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0040] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0041] In this application, "one or more" means any one, two or more of the listed items.

[0042] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0045] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0047] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] Traditional processes for preparing diamond / aluminum composites include spark plasma sintering, vacuum hot pressing, pressureless infiltration, extrusion casting, and gas pressure infiltration. Spark plasma sintering and vacuum hot pressing, both belonging to the field of powder metallurgy, offer advantages such as low preparation temperature and high efficiency, but also suffer from weak interfacial bonding and low density. Extrusion casting offers advantages such as low equipment requirements, fast infiltration speed, simple process, and high efficiency, but residual gas between diamond particles cannot be expelled in time during rapid molding, resulting in gas or pores in the diamond / aluminum composite, affecting material properties. Pressureless infiltration and gas pressure infiltration facilitate sufficient contact between molten aluminum and diamond, improving interfacial bonding and eliminating the problem of residual gas buildup. However, prolonged contact between diamond and aluminum under high temperature or high pressure conditions can easily lead to harmful interfacial reactions, and pressureless infiltration suffers from incomplete infiltration and low density.

[0049] Considering the advantages and disadvantages of the above preparation processes, our engineers, through long-term practical production and R&D, have discovered that compared to gas pressurization, using a combination of vacuum pumping and mechanical pressurization results in faster pressurization speed and more uniform pressure. This allows molten aluminum to penetrate into diamond particles in a very short time, avoiding prolonged contact between diamond and aluminum under high temperature or high pressure conditions. This reduces the probability of harmful interfacial reactions and decreases the formation of the Al4C3 phase. After extensive creative exploration, we have obtained the diamond / aluminum composite material with excellent density and thermal conductivity as described in this application.

[0050] Please see Figure 1 According to a first aspect of this application, a method for preparing a diamond / aluminum composite material is provided, comprising the following steps:

[0051] S10, diamond particles are made into a preform;

[0052] S20, place the preform in the composite mold and pour molten aluminum onto the preform;

[0053] S30, applying pressure to the molten aluminum using a vacuum and mechanical pressurization, causing the molten aluminum to penetrate into the diamond particles; and

[0054] S40, cooling.

[0055] The above-mentioned method for preparing diamond / aluminum composite materials uses a combination of vacuuming and mechanical pressurization, which allows molten aluminum to penetrate into diamond particles in a very short time. This avoids prolonged contact between diamond and aluminum under high temperature or high pressure conditions, reducing the probability of harmful interfacial reactions and decreasing the formation of the Al4C3 phase, thereby improving the thermal conductivity and stability of the diamond / aluminum composite materials.

[0056] It should be noted that for composite materials based on melt infiltration processes, the preform is a porous medium with a specific shape pre-generated to more accurately control the volume fraction of the reinforcement. In some embodiments, the preform is formed by the natural stacking of diamond particles. In other embodiments, the preform is formed by vibrating the diamond particles in a constant-volume device. Vibration is used to increase the volume fraction of diamond powder. In a naturally stacked state, the random overlap of diamond particles leads to more voids in the internal stack, resulting in a relatively lower volume fraction of diamond. After vibration, the diamond is more densely stacked, resulting in a higher volume fraction, higher thermal conductivity, lower coefficient of thermal expansion, and better performance in the prepared composite material. Optionally, ultrasonic vibration can better quantify the volume fraction of diamond in the composite material.

[0057] In some implementations, mechanical supercharging includes increasing the pressure to a preset pressure value within a predetermined time and holding the pressure at that preset pressure value.

[0058] Optionally, the preset pressure value for mechanical supercharging is 1 MPa to 40 MPa. Understandably, it can also be 10 MPa to 40 MPa, 10 MPa to 30 MPa, 20 MPa to 40 MPa, 20 MPa to 30 MPa, etc., without specific limitation. A higher preset pressure value compensates for the shrinkage of the aluminum matrix during cooling, resulting in a denser interfacial bond, but also increases internal thermal stress; however, the preset pressure value should not be too high. Within this preset pressure range, diamond / aluminum composite materials with superior overall performance can be obtained. As an example, the preset pressure value can be, but is not limited to, 2 MPa, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, and any value between them.

[0059] Optionally, the holding time for mechanical supercharging is from 1 minute to 60 minutes, for example, 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes.

[0060] 55 min and any value in between. Further optionally, the holding time for mechanical supercharging is 1 min to 10 min.

[0061] Optionally, the pressurization time for mechanical pressurization is 0.1 min to 5 min. Understandably, it can also be 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, etc., without specific limitation. In this application, the pressurization time refers to the time from the contact between the molten aluminum and the diamond (i.e., the start of pouring the molten aluminum) until the system pressure reaches the preset pressure value. Too long a pressurization time easily leads to the formation of the Al4C3 phase, while too short a time will result in incomplete impregnation. As an example, the pressurization time can be 0.5 min, 1 min, 5 min, but is not limited to, or any value between them.

[0062] In some embodiments, vacuuming is used to achieve a relative vacuum level of -50 kPa to 0 kPa, such as -5 kPa, -40 kPa, -30 kPa, -20 kPa, -10 kPa, -15 kPa, -25 kPa, -35 kPa, -45 kPa, -12 kPa, -28 kPa, -50 kPa, and any value between them. A vacuum level within this range can further promote the infiltration of molten aluminum into the diamond particles, while also ensuring the timely removal of residual gas between the diamond particles, thereby improving the density of the diamond / aluminum composite material.

[0063] In some embodiments, the temperature of the molten aluminum is between 710°C and 860°C, for example, 720°C, 740°C, 760°C, 780°C, 800°C, 820°C, 840°C, and 850°C. The aluminum melting point is 660°C. A temperature higher than the aluminum melting point can prevent the molten aluminum from solidifying prematurely, but it should not be too high. Within this range, the molten aluminum can achieve a better impregnation effect.

[0064] Please see Figure 2 In some embodiments, step S12 is included before step S20, and step S12 includes preheating the preform. Those skilled in the art have further discovered that preheating can improve the interfacial bonding between diamond and aluminum. Through preheating, a reaction occurs between diamond and aluminum at the interfacial contact point to form a thin layer of aluminum carbide, thereby increasing the wettability of diamond. Although aluminum carbide is a harmful impurity phase, the presence of a small amount of aluminum carbide is actually beneficial.

[0065] In some embodiments, the preheating process includes heating the preform to a preset temperature value and holding it at the preset temperature value.

[0066] Optionally, the preset temperature for preheating is 500℃ to 750℃, such as 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃, and any value between them. A preset temperature within this range yields better results. If the preset temperature is too low, incomplete impregnation will occur, resulting in poor bonding strength between diamond and aluminum. If the preset temperature is too high, diamond oxidation or graphitization will occur, leading to an increase in the Al4C3 phase at the interface.

[0067] Optionally, the preheating treatment holding time is from 10 min to 90 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, and any value between them. A preheating treatment holding time within this range allows the preheating temperature of the preform to tend to be uniform, thereby facilitating impregnation. More preferably, the preheating treatment holding time is from 45 min to 60 min.

[0068] Optionally, the heating rate of the preheating treatment is 2℃ / min to 20℃ / min, for example, 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, 18℃ / min, and any value between them. The faster the heating rate, the higher the efficiency, but an excessively fast heating rate will cause the temperature of the part of the diamond in contact with the heat source to be too high, while the core temperature will be too low, resulting in uneven preheating temperature.

[0069] In some embodiments, the volume average particle size (Dv50) of the diamond particles is between 45 micrometers and 500 micrometers, for example, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 75 micrometers, 80 micrometers, 85 micrometers, 90 micrometers, 95 micrometers, 100 micrometers, 150 micrometers, 200 micrometers, 250 micrometers, 300 micrometers, 350 micrometers, 400 micrometers, 450 micrometers, and any value between them. The volume average particle size (Dv50) of the diamond particles is a factor affecting the thermal conductivity of diamond / aluminum composites. A larger volume average particle size (Dv50) results in higher thermal conductivity and a lower coefficient of thermal expansion. However, it should not be too large, as an excessively large volume average particle size (Dv50) will deteriorate the mechanical properties of the composite. Furthermore, when the volume average particle size (Dv50) reaches a certain value, the increase in thermal conductivity slows down, and the coefficient of thermal expansion increases due to the reduced interface area. Diamond / aluminum composites prepared with a volume average particle size Dv50 of diamond particles within this range exhibit high thermal conductivity, low coefficient of expansion, and excellent mechanical properties, resulting in superior overall performance.

[0070] In some specific embodiments, the diamond particles are single-crystal diamonds. Single-crystal diamonds have better thermal conductivity and other properties, resulting in diamond / aluminum composite materials with superior overall performance.

[0071] In some embodiments, the molten aluminum is obtained by refining aluminum-containing metal materials. Refined molten aluminum contains fewer impurities, resulting in diamond / aluminum composite materials with superior overall performance.

[0072] Optionally, the aluminum-containing metal material includes pure aluminum and / or aluminum alloys, and more preferably aluminum alloys. The presence of other elements in the aluminum alloy can improve the performance of the composite material, resulting in a material with superior overall performance.

[0073] Alternatively, the aluminum alloy may include one or more of the following: Al-Si alloy, Al-Si-Cu alloy, Al-Si-Mg alloy, Al-Cu alloy, Al-Mg alloy, Al-Cu-Mg alloy, Al-Zn-Cu alloy, Al-Zn-Mg-Cu alloy, and Al-Si-Cu-Mg alloy. The specific type of aluminum alloy can be selected according to actual needs.

[0074] In some embodiments, step S00 is included before step S10. Step S00 includes pre-treating the diamond particles. The pre-treatment may include steps such as screening, washing, and drying.

[0075] Because diamond is the hardest material in nature, diamond / aluminum composites are difficult to machine using traditional methods to obtain components of the required specific shapes and sizes. Using specialized machining methods such as laser processing would increase processing costs. In some implementations, preforms are prepared using near-net-shape molds to address the difficulty of machining diamond / aluminum composites.

[0076] In some embodiments, the process further includes placing a cold salt layer below the preform before pouring molten aluminum onto it. Specifically, before placing the preform in the composite mold in step S20, the process also includes placing a cold salt layer within the composite mold so that the preform is positioned above the cold salt layer. The purpose of the cold salt layer is twofold: firstly, to prevent molten aluminum from flowing into the vacuum pipe during vacuuming, and secondly, to prevent molten aluminum from seeping directly down from the mold edge. Furthermore, after penetrating the diamond, the molten aluminum continues to seep downwards; upon encountering the cold salt layer, it instantly solidifies, providing resistance to the continued flow of molten aluminum through the diamond and ensuring high density.

[0077] The cold salt layer can be formed by any conventional method in the art, such as pressing salt particles into a composite mold. The salt particles have a particle size of 300 μm to 1200 μm and can be industrial salt or other known salt particles that are easily soluble in water. The salt particles do not react with diamond or aluminum. In some embodiments, the thickness of the cold salt layer is 10 mm to 60 mm, and the thickness of the liquid layer formed by pouring molten aluminum into the composite mold is 50 mm to 80 mm. In some embodiments, the temperature of the salt particles in the cold salt layer is lower than the preset temperature value of the preheating treatment of the preform. In some embodiments, the temperature of the salt particles in the cold salt layer is room temperature (20°C to 25°C), i.e., conventionally unheated salt particles.

[0078] In some embodiments, step S40 cooling is performed using either mold-based cooling or air cooling. Mold-based cooling refers to natural cooling under the insulation of the mold. Air cooling refers to natural cooling in the air. Excessive cooling rate can cause aluminum to shrink rapidly and detach from the diamond interface, increasing interfacial thermal resistance and reducing the composite material's performance. Insufficient cooling rate results in low production efficiency. A moderate cooling rate, either mold-based or air cooling, reduces the high-temperature contact time between diamond and molten aluminum, effectively preventing or reducing the reaction between diamond and aluminum at the interface to form harmful Al4C3, thereby improving the thermal conductivity and stability of the diamond / aluminum composite material.

[0079] The near-net-shape forming mold described in this application is any conventional near-net-shape forming mold known in the art. In some embodiments, the near-net-shape forming mold is made of graphite, quartz, ferroalloy, ceramic, or stainless steel, preferably stainless steel. Specific examples of ceramics include, but are not limited to, alumina ceramics, and specific examples of stainless steel include, but are not limited to, 304 stainless steel. The material of the near-net-shape forming mold is a factor affecting the surface quality of the diamond / aluminum composite material. For example, graphite is relatively soft, and an excessively hard diamond will press into the graphite, resulting in an uneven and unclean surface after demolding; ceramic, being too hard, will cause the diamond to be exposed without aluminum coverage on the outermost layer. Different materials can be selected for different needs; for example, covering the outermost layer with aluminum facilitates welding, while having no aluminum on the outermost layer provides higher thermal conductivity.

[0080] Some embodiments of this application also provide a composite mold. See also... Figure 3 The composite mold includes a base 7, a mold 15, and a pressure head 12.

[0081] The base 7 includes a hydraulic ejector rod 18, a demolding top plate 9, and a vacuum pipe 8. The demolding top plate 9 is provided with an exhaust channel 16.

[0082] The mold 14 includes multiple sidewalls, which together form a cavity.

[0083] The base 7 and the mold 14 are nested together, and the demolding top plate 9 is located inside the cavity of the mold 14. The pressure head 12 is movably connected to the mold 14 and can move within the cavity of the mold 14.

[0084] In some embodiments, the base 7 may further include a sealing ring 17.

[0085] In some embodiments, a filter screen (not shown) is provided on the exhaust passage 16.

[0086] In some embodiments, the composite mold further includes a heating assembly (not shown), a pressurizing assembly (not shown), or a vacuum system (not shown).

[0087] In some specific embodiments, the pressurization assembly includes a Y32-315 four-column hydraulic press, which provides mechanical pressurization power to the composite mold.

[0088] When using this composite mold, preform 15 ( Figure 3The diagram shows a preform 15 prepared using a near-net-shape forming mold, placed inside the cavity of mold 14, with molten aluminum 11 placed on top of the preform 15. In some embodiments, cold salt 10 can be pre-placed inside the cavity of mold 14 to create a cold salt environment below and around the preform 15. The purpose of adding cold salt is to prevent molten aluminum from flowing into the vacuum pipe 8. After penetrating the diamond, the molten aluminum continues to seep downwards, and upon encountering the cold salt, it instantly solidifies, preventing not only the molten aluminum from entering the vacuum pipe 8 but also blocking its continued flow past the diamond, providing resistance. At the other end, under the pressure of the pressure head 12, the diamond is completely filled into the cavity by the molten aluminum, ensuring high density. In some embodiments, graphite felt 13 is further provided on the preform 15 to prevent the diamond from being dispersed when the molten aluminum is poured in, and also to filter impurities in the molten aluminum.

[0089] A second aspect of this application provides a diamond / aluminum composite material prepared by the preparation method of any of the above embodiments.

[0090] A third aspect of the embodiments of this application further provides the application of the above-described diamond / aluminum composite material in the preparation of electronic packaging products or heat sink products, such as heat dissipation substrates.

[0091] The following are specific embodiments. They are intended to provide a more detailed description of this application to help those skilled in the art and researchers better understand it. The technical conditions described do not constitute any limitation on this application. Any modifications made within the scope of the claims of this application are protected by the claims.

[0092] Unless otherwise stated, all raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. All instruments are conventionally selected in the art. Experimental methods not specifically described in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0093] Example 1

[0094] 1. Preform Preparation

[0095] Single-crystal diamond particles with a particle size of 70-80 mesh (particle diameter of 180-212μm) are ultrasonically cleaned sequentially with deionized water and alcohol. The cleaned diamond particles are then placed in an oven and baked at 80°C for 5 hours. The dried diamond particles are then loaded into a near-net-shape mold and ultrasonically compacted to form a preform.

[0096] 2. Precast heating

[0097] The preform prepared in step 1 is placed in a pit furnace for preheating treatment. The preheating conditions are to heat to 650℃ at a rate of 10℃ / min and hold for 60min.

[0098] 3. Preparation of molten aluminum

[0099] Aluminum alloy ingots of grade ZL102 are placed in an aluminum melting furnace. The furnace is then heated to 150°C, which is higher than the melting point of aluminum (the melting point of aluminum is 660°C, so the temperature here is 810°C) to begin melting. After the aluminum ingots are completely melted, they are stirred with a filter spoon and impurities such as oxide slag are removed. Then, a refining agent is added to the molten aluminum, stirred, and slag is removed to obtain molten aluminum.

[0100] 4. Impregnation composite

[0101] The preform prepared in step 2 is placed into the cavity of the composite mold. Cold salt is placed around the preform as filler. Molten aluminum is poured into the preform, and the vacuum system is turned on to evacuate the system to -50 kPa. Then, it is rapidly pressed at the preset pressure of 8 MPa (pressurization time is 1 min), and the pressure is held for 5 min before being released. The mechanical pressurization is provided by a four-column hydraulic press of model Y32-315. The specific structure of the composite mold is as follows. Figure 3 As shown.

[0102] 5. Cooling

[0103] The pressed blank from step 4 is ejected, cooled to room temperature in air, and then demolded after removing the near-net-shape mold. A thin plate-shaped diamond / aluminum composite material with dimensions of 60mm*60mm*5mm is obtained.

[0104] It should be noted that the near-net-shape forming mold in this embodiment is made of stainless steel.

[0105] Examples 2-9

[0106] The preparation methods for Examples 2-9 are similar to those for Example 1. The difference lies in the adjustment of relevant parameters during the preparation process, as detailed in Table 1 below. " / " indicates that the corresponding parameter does not exist.

[0107] Examples 10-13

[0108] The preparation methods of Examples 10-13 are similar to those of Example 1. The difference lies in that the near-net-shape molds are made of carbon steel, graphite, ceramic, and stainless steel, respectively.

[0109] like Figure 5 As shown, the surface microstructure of diamond / aluminum composite materials prepared using near-net-shape molds of different materials is illustrated.

[0110] Examples 14-17

[0111] The preparation methods of Examples 14-17 are similar to those of Example 1. The difference lies in that the aluminum liquid is prepared using pure aluminum, and four different diamond particles of different sizes are used.

[0112] Comparative Example 1

[0113] The preparation method of Comparative Example 1 is similar to that of Example 1, except that the vacuuming step is omitted.

[0114] Comparative Example 2

[0115] The preparation method of Comparative Example 2 is similar to that of Example 1, except that step 4 is replaced by: placing the preform prepared in step 2 into a pneumatic impregnation furnace, evacuating it, and then pressurizing it with gas at a pressure of 1 MPa for 30 min and holding it at 40 min.

[0116] The process parameters for the preparation methods of Examples 1-9 and Comparative Examples 1-2 are listed in Table 1 below:

[0117] Table 1

[0118]

[0119]

[0120] The diamond / aluminum composite materials prepared in Examples 1-9, 14-17 and Comparative Examples 1-2 were subjected to morphology, thermal conductivity and density tests. The results of the thermal conductivity and density tests are shown in Table 2 below.

[0121] The test conditions or standards for each performance test item are as follows:

[0122] 1. Morphological analysis

[0123] The interface and fracture morphology of the composite material were observed using a Merlin field emission scanning electron microscope manufactured by Zeiss AG, Germany. Figure 4 As shown, the diamond particle phase, fracture morphology, and interface morphology in the diamond / aluminum composite material are illustrated.

[0124] 2. Thermal conductivity

[0125] (1) Thermal conductivity: determined according to the method specified in GB / T22588-2008, at room temperature (25±5℃).

[0126] (2) Coefficient of thermal expansion: Measured according to the method specified in GJB 332A-2004, with an initial test temperature of (25±5)℃ and an end test temperature of 200℃.

[0127] 3. Density

[0128] The actual density of diamond / aluminum composites is determined according to the method specified in GB / T 1423-1996. The theoretical density is calculated according to the mixing law of composite materials. The density of diamond / aluminum composites is numerically the ratio of the actual density to the theoretical density of the composite material.

[0129] Table 2

[0130]

[0131]

[0132] As shown in the table above, the preparation method provided in this application can obtain diamond / aluminum composite materials with superior performance.

[0133] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a diamond / aluminum composite material, characterized in that, Includes the following steps: Diamond particles are made into preforms; The preform is placed in a composite mold, and molten aluminum is poured onto the preform. A vacuum is drawn and pressure is applied to the molten aluminum using mechanical pressurization, causing the molten aluminum to penetrate into the diamond particles; And cooling; The mechanical supercharging includes increasing the pressure to a preset pressure value within a predetermined time and maintaining the pressure at the preset pressure value. The supercharging time is 0.1 min to 5 min. The preset pressure value of the mechanical supercharger is 1MPa ~ 40MPa; The pressure holding time for the mechanical supercharger is 1 min to 60 min.

2. The method for preparing the diamond / aluminum composite material according to claim 1, characterized in that, The mechanical supercharger satisfies at least one of the following characteristics (1) to (2): (1) The preset pressure value of the mechanical supercharger is 10MPa ~ 40MPa; (2) The pressure holding time of the mechanical supercharging is 1 min to 10 min.

3. The method for preparing the diamond / aluminum composite material according to claim 1, characterized in that, The vacuuming step brings the system relative vacuum to -50 kPa to 0 kPa.

4. The method for preparing the diamond / aluminum composite material according to claim 1, characterized in that, The temperature of the molten aluminum is 710℃~860℃.

5. The method for preparing the diamond / aluminum composite material according to claim 1, characterized in that, Before the steps of placing the preform in the composite mold and pouring molten aluminum onto the preform, the method further includes a step of preheating the preform. The preheating process includes heating the preform to a preset temperature value and holding it at the preset temperature value.

6. The method for preparing the diamond / aluminum composite material according to claim 5, characterized in that, The preheating treatment satisfies at least one of the following characteristics (4) to (6): (4) The preset temperature value of the preheating treatment is 500℃~750℃; (5) The heat preservation time of the preheating treatment is 10 min to 90 min; (6) The heating rate of the preheating treatment is 2℃ / min to 20℃ / min.

7. The method for preparing the diamond / aluminum composite material according to claim 1, characterized in that, The cooling is achieved by cooling the composite mold or by air cooling.

8. The method for preparing the diamond / aluminum composite material according to any one of claims 1 to 7, characterized in that, The diamond particles have a particle size of 45 micrometers to 500 micrometers.

9. The method for preparing the diamond / aluminum composite material according to claim 8, characterized in that, The diamond particles have a diameter of 180 micrometers to 212 micrometers.

10. The method for preparing the diamond / aluminum composite material according to claim 8, characterized in that, The diamond particles are single-crystal diamonds.

11. The method for preparing the diamond / aluminum composite material according to any one of claims 1 to 7, characterized in that, The molten aluminum is obtained by refining aluminum-containing metal materials, including pure aluminum and / or aluminum alloys.

12. The method for preparing the diamond / aluminum composite material according to claim 11, characterized in that, The aluminum alloy includes one or more of the following: Al-Si alloy, Al-Si-Cu alloy, Al-Si-Mg alloy, Al-Cu alloy, Al-Mg alloy, Al-Cu-Mg alloy, Al-Zn-Cu alloy, Al-Zn-Mg-Cu alloy, and Al-Si-Cu-Mg alloy.

13. The method for preparing the diamond / aluminum composite material according to any one of claims 1 to 7, characterized in that, The preform is prepared using a near-net-shape forming mold.

14. A diamond / aluminum composite material prepared by the preparation method according to any one of claims 1 to 13.

15. The application of the diamond / aluminum composite material as described in claim 14 in the preparation of electronic packaging products or heat sink products.

Images