Diamond particle gradient reinforced metal-based thermal management material and preparation method thereof

Abstract

The invention discloses a diamond particle gradient reinforced metal-based thermal management material and a preparation method thereof. The thermal management material is composed of multiple layers of structures, the preparation process comprises the steps that mixed powder of diamonds and metal matrixes with different sizes is sprayed to the surface of the metal matrix through cold gas power spraying, meanwhile, annealing heat treatment is assisted, a compact multilayer diamond coating is prepared, the sizes and the contents of particles of the diamonds in each layer are different, corresponding thermal expansion coefficients are different, and the thermal management material is prepared. During packaging application, the chip can be welded to the functional layer matched with the chip in thermal expansion coefficient, so that the thermal expansion coefficient of the chip is matched with the thermal expansion coefficient of the functional layer of the thermal management material, the welding internal stress between the chip and the thermal management material is reduced, and the service life of electronic equipment is prolonged; the thermal management material has multiple functional layers with different thermal expansion coefficients, so that the thermal management material can be used for packaging various chips with different thermal expansion coefficients, and is simple and convenient in preparation process, low in cost and easy to popularize and apply.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal management material preparation, and in particular relates to a diamond particle gradient enhanced metal-based thermal management material and a preparation method thereof. Background Art

[0002] Additive manufacturing technology that uses cold air dynamic spraying (also known as cold spraying) to deposit metal is a non-heat input technology. Its principle is that high kinetic energy powder particles collide with the base material in a solid state and undergo severe plastic deformation instantly, thereby combining with each other to form a coating (bulk material). Compared with traditional additive manufacturing technology, the biggest advantage of cold spray additive manufacturing is low temperature, which can prepare heat-sensitive metal materials, including nanocrystalline metals, amorphous metallic glasses, and alloys containing high vapor pressure elements. Diamond / metal matrix composites play an extremely important role in electronic packaging materials, aerospace, military defense and other fields. At present, it is rapidly developing in the direction of high integration, high power and high performance. As a result, the influence of its thermal effect is becoming more and more obvious, so the thermal management materials that play the role of chip packaging and heat dissipation are also facing greater challenges. The matching degree of its thermal conductivity and its thermal expansion coefficient with the chip is related to the reliability and service life of electronic equipment. Therefore, it has become a top priority to develop new thermal management materials with controllable thermal expansion coefficient and high reliability. Summary of the invention

[0003] In view of the shortcomings of the prior art, the first object of the present invention is to provide a method for preparing a diamond particle gradient enhanced metal-based thermal management material. The preparation method of the present invention selects mixed powders of diamonds of different sizes and a metal matrix as spraying powder. During the spraying process, the mixed powders of diamonds and the metal matrix collide with the metal matrix at high speed. Diamonds of different sizes are deposited on different layer structures of the thermal management material, respectively, to prepare a diamond / metal-based composite material with multiple functional layers of different thermal expansion coefficients to simultaneously meet the packaging of multiple chips with different thermal expansion coefficients.

[0004] The second object of the present invention is to provide a diamond particle gradient enhanced metal-based thermal management material prepared by the above preparation method.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention discloses a method for preparing a diamond particle gradient enhanced metal-based thermal management material, comprising mixing N portions of diamond powder of different sizes with metal powder to obtain N portions of mixed powder, spraying the N portions of mixed powder onto the surface of a metal substrate in sequence by cold air power spraying to obtain a metal substrate containing N functional layers, and finally annealing the metal substrate containing the N functional layers to obtain the diamond particle gradient enhanced metal-based thermal management material;

[0007] During the spraying, the areas of the functional layers are controlled to be the same.

[0008] The preparation method of the present invention selects mixed powders of diamonds of different sizes and a metal matrix as spray powders. During the spraying process, the mixed powders of diamonds and a metal matrix collide with the metal matrix at high speed. Diamonds of different sizes are respectively deposited on different layer structures of the thermal management material. In the N-layer coating, the diamond particles in each layer have different sizes and / or contents, and the corresponding thermal expansion coefficients are different. The multiple functional layers with different thermal expansion coefficients can simultaneously meet the needs of packaging a variety of chips with different thermal expansion coefficients.

[0009] In a preferred embodiment, when N is 3, the particle size ranges of the diamond powder are 10-30 μm, 30-50 μm, and 50-100 μm, respectively.

[0010] In a preferred solution, the volume fraction of diamond powder in the N parts of mixed powder is 10% to 70%. In the present invention, the volume fraction of diamond powder is controlled within the above range, and the performance is excellent.

[0011] In a preferred solution, the metal powder has the same composition as the metal matrix. In the present invention, the metal powder and the metal matrix need to have the same composition. If they are different, metal alloying will occur, which will affect the thermal conductivity and thermal expansion coefficient to a certain extent.

[0012] In a preferred embodiment, the metal substrate is selected from an aluminum substrate or a copper substrate.

[0013] The preferred solution is that the process parameters of cold air power spraying are: using He gas as the working gas, the gas temperature is 300-600°C, the gas pressure is 0.5-5.0MPa, and the spraying distance is 10-40mm.

[0014] In the present invention, the above-mentioned process parameters are used when each functional layer is sprayed. The inventors have found that when the process parameters of cold air power spraying are controlled within the scope of the present invention, the performance of the final diamond particle gradient enhanced metal-based thermal management material is optimal. For example, if the spraying spacing is too large, it is easy to cause insufficient kinetic energy when the particles hit the substrate, the ability of the particles to undergo plastic deformation is weakened, the deposition efficiency is reduced, and the porosity of the coating is increased and the bonding strength of the coating is reduced; if the spraying spacing is too small, the sprayed particles will have a strong erosion effect on the substrate, the deposition of the particles is very difficult, and serious particle rebound will occur. Gas pressure will affect the acceleration process of the particles. The acceleration of the particles is linearly related to the stagnation pressure. As the gas pressure increases, the acceleration of the particles also increases, which is conducive to the particles reaching the carrier gas flow rate in a shorter time and distance.

[0015] In a preferred solution, the annealing temperature is 200°C to 500°C, and the holding time is 2 to 10 hours. The annealing temperature is controlled within the above range to achieve the best final performance. If the annealing temperature is too low, the functional layer can only undergo a recovery process, and the broken grains during the cold spraying process do not undergo recrystallization; when the temperature is too high, it may exceed the melting point of the matrix, and the time is too long, and the broken grains undergo recrystallization, but the grains grow too large, which also affects the performance. If the time is too short, the recrystallization may not be complete.

[0016] The present invention also provides a diamond particle gradient enhanced metal-based thermal management material prepared by the above preparation method.

[0017] The diamond particle gradient enhanced metal-based thermal management material has N functional layers, and any two functional layers have different thermal expansion coefficients.

[0018] Principles and advantages

[0019] The present invention provides a diamond particle gradient enhanced metal-based thermal management material and a preparation method thereof. He gas is used as a gas source, and mixed powders of diamonds of different sizes and a metal matrix are used as spray powders. During the spraying process, the mixed powders of diamonds and a metal matrix collide with the metal matrix at high speed, and diamonds of different sizes are deposited on different layer structures of the thermal management material, respectively, to prepare a diamond / metal-based composite material with multiple functional layers of different thermal expansion coefficients, so as to simultaneously meet the packaging of multiple chips with different thermal expansion coefficients.

[0020] The diamond particle gradient enhanced metal-based thermal management material provided by the present invention has different diamond particle sizes and contents in each layer, and the corresponding thermal expansion coefficients are different. When packaged and applied, the chip can be welded to the functional layer matching its thermal expansion coefficient, so that the thermal expansion coefficient of the chip matches the thermal expansion coefficient of the thermal management material functional layer, thereby reducing the welding internal stress between the chip and the thermal management material and improving the service life of the electronic device. Since the thermal management material has multiple functional layers with different thermal expansion coefficients, it can simultaneously meet the packaging of multiple chips with different thermal expansion coefficients, and the preparation process is simple, the cost is low, and it is easy to promote and apply. It is a breakthrough in the application of cold spraying technology to thermal management materials, and the preparation technology has not been reported at home and abroad.

[0021] The advantages and beneficial effects of the present invention are:

[0022] 1. The diamond / aluminum-based composite material prepared by the present invention has easy-to-obtain raw materials, simple process, low cost, controllable thickness and high preparation feasibility.

[0023] 2. The thermal management material prepared by the present invention has multiple diamond / metal matrix composite materials with different thermal expansion coefficient functional layers, which can simultaneously meet the needs of packaging multiple chips with different thermal expansion coefficients. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of the diamond particle gradient enhanced metal-based thermal management material of the present invention.

[0025] In the figure: 1-base metal powder, 2-diamond particles, 3-cold spray system, 4-gradient diamond coating, 5-metal substrate. DETAILED DESCRIPTION

[0026] In the specific implementation process, the present invention relates to a diamond particle gradient enhanced metal-based thermal management material and a preparation method thereof. First, diamonds of different sizes and metal matrix mixed spray powder and metal matrix are prepared; then cold air power spraying is used to deposit diamonds of different sizes on different layer structures of the thermal management material to prepare a diamond / metal-based composite material with multiple functional layers of different thermal expansion coefficients; finally, appropriate annealing heat treatment is performed to effectively avoid brittle fracture of the diamond / metal-based composite material after hardening. The specific steps of the method are as follows:

[0027] Step 1: Material selection: The particle sizes of diamond particles are 10-30 μm, 30-50 μm, and 50-100 μm respectively; the metal-based material can be an aluminum matrix, a copper matrix, etc.

[0028] Step 2: Spraying: Using cold spray equipment, the diamond and metal matrix mixed spray powders of different sizes in step 1 are deposited on different layers of the thermal management material to prepare diamond / metal matrix composite materials with multiple functional layers of different thermal expansion coefficients. The operating conditions of the cold spray equipment are: temperature 300-600°C, pressure 0.5-5.0MPa, spray distance 10-40mm, and He gas spraying.

[0029] Step 3: Heat treatment: The prepared diamond / metal matrix composite material is annealed in a muffle furnace.

[0030] The temperature range of the heat treatment is 200°C to 500°C, and the insulation time is 2h to 10h.

[0031] In the obtained diamond / metal matrix composite material, the diamond particle size and content in each layer are different, and the corresponding thermal expansion coefficients are different. The multiple functional layers with different thermal expansion coefficients can simultaneously meet the packaging needs of multiple chips with different thermal expansion coefficients.

[0032] The embodiments of the present invention are described in detail below. They are implemented based on the technical solution of the invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0033] Example 1

[0034] Diamond particles with average particle sizes of 10μm, 30μm, and 50μm were selected and mixed with Al powder to form cold spray powder, and commercial pure Al was used as the matrix material. Then, under the conditions of He gas as the working gas, gas temperature of 300℃, gas pressure of 1MPa, and spraying distance of 20mm, a diamond powder was deposited on each Al matrix functional layer of the thermal management material using cold spray equipment, and the volume fraction of diamond was 30%. Finally, the prepared functional layer diamond / Al-based composite material was vacuum heat treated at 200℃ for 4h. In this embodiment, the nozzle of the cold spray equipment was not blocked, and the thermal expansion coefficient of the three functional layers of the prepared diamond / Al composite material was tested, and the thermal expansion coefficients of each layer were found to be 4.61×10 －6 K －1 , 5.32×10 －6 K －1 and 6.78×10 －6 K －1 .

[0035] Example 2

[0036] Diamond particles with average particle sizes of 15μm, 35μm, and 60μm were selected and mixed with Al powder to form cold spray powder, and commercial pure Al was used as the matrix material. Then, under the conditions of He gas as the working gas, gas temperature of 400℃, gas pressure of 2MPa, and spraying distance of 30mm, a diamond powder was deposited on each Al matrix functional layer of the thermal management material using cold spray equipment, and the volume fraction of diamond was 40%. Finally, the prepared functional layer diamond / Al-based composite material was vacuum heat treated at 300℃ for 5h. In this embodiment, the nozzle of the cold spray equipment was not blocked, and the thermal expansion coefficient of the three functional layers of the prepared diamond / Al-based composite material was tested, and the thermal expansion coefficients of each layer were 5.68×10 －6 K －1 , 6.32×10 － 6 K －1 and 7.48×10 －6 K －1 .

[0037] Example 3

[0038] Diamond particles with average particle sizes of 20μm, 40μm, and 70μm were selected and mixed with Cu powder to form cold spray powder, and commercial pure Cu was used as the matrix material. Then, under the conditions of He gas as the working gas, gas temperature of 500℃, gas pressure of 3MPa, and spraying distance of 25mm, a diamond powder was deposited on each Cu matrix functional layer of the thermal management material using cold spray equipment, and the volume fraction of diamond was 60%. Finally, the prepared functional layer diamond / Cu-based composite material was vacuum heat treated at 400℃ for 6h. In this embodiment, the nozzle of the cold spray equipment was not blocked, and the thermal expansion coefficient of the three functional layers of the prepared diamond / Cu-based composite material was tested, and the thermal expansion coefficients of each layer were found to be 7.64×10 －6 K －1 ,8.50×10 － 6 K －1 and 9.78×10 －6 K －1 .

[0039] Example 4

[0040] Diamond particles with average particle sizes of 25 μm, 45 μm, and 90 μm were selected and mixed with Cu powder to form cold spray powder, and commercial pure Cu was used as the matrix material. Then, under the conditions of He gas as the working gas, gas temperature of 600 ° C, gas pressure of 5 MPa, and spraying distance of 40 mm, a diamond powder was deposited on each Cu matrix functional layer of the thermal management material using cold spray equipment, and the volume fraction of diamond was 70%. Finally, the prepared functional layer diamond / Cu-based composite material was vacuum heat treated at 500 ° C for 8 hours. In this embodiment, the nozzle of the cold spray equipment was not blocked, and the thermal expansion coefficient of the three functional layers of the prepared diamond / Cu-based composite material was tested, and the thermal expansion coefficients of each layer were found to be 8.67×10 －6 K －1 ,9.01×10 － 6 K －1 and 9.98×10 －6 K －1 .

[0041] The results of the embodiments show that the method of the present invention has a simple operation process and low cost. Diamonds of different sizes are deposited on different layer structures of the thermal management material to prepare a diamond / metal-based composite material with multiple functional layers with different thermal expansion coefficients to simultaneously meet the packaging needs of multiple chips with different thermal expansion coefficients.

Claims

1. A method for preparing a diamond particle gradient enhanced metal-based thermal management material, characterized in that: N parts of mixed powder are obtained by mixing N parts of diamond powder of different sizes with metal powder, and the N parts of mixed powder are sprayed onto the surface of a metal substrate in sequence by cold air power spraying to obtain a metal substrate containing N functional layers, and finally the metal substrate containing N functional layers is annealed to obtain a diamond particle gradient enhanced metal-based thermal management material; During the spraying, the areas of the functional layers are controlled to be the same.

2. The method for preparing a diamond particle gradient enhanced metal-based thermal management material according to claim 1, characterized in that: When N is 3, the particle size ranges of the diamond powder are 10-30 μm, 30-50 μm, and 50-100 μm, respectively.

3. The method for preparing a diamond particle gradient enhanced metal-based thermal management material according to claim 1, characterized in that: In the N parts of mixed powder, the volume fraction of diamond powder is 10% to 70%.

4. The method for preparing a diamond particle gradient enhanced metal-based thermal management material according to claim 1, characterized in that: The metal powder has the same composition as the metal matrix.

5. The method for preparing a diamond particle gradient enhanced metal-based thermal management material according to claim 1, characterized in that: The metal substrate is selected from an aluminum substrate or a copper substrate.

6. The method for preparing a diamond particle gradient enhanced metal-based thermal management material according to claim 1, characterized in that: The process parameters of cold air dynamic spraying are: using He gas as the working gas, the gas temperature is 300-600°C, the gas pressure is 0.5-5.0MPa, and the spraying distance is 10-40mm.

7. The method for preparing a diamond particle gradient enhanced metal-based thermal management material according to claim 1, characterized in that: The annealing treatment is carried out at a temperature of 200° C. to 500° C. and a heat preservation time of 2 to 10 hours.

8. A diamond particle gradient enhanced metal-based thermal management material prepared by the preparation method according to any one of claims 1 to 7.

9. The diamond particle gradient enhanced metal-based thermal management material according to claim 8, characterized in that: The diamond particle gradient enhanced metal-based thermal management material has N functional layers, and any two functional layers have different thermal expansion coefficients.

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