Preparation method of copper-coated diamond-tin-based alloy composite material

Abstract

A preparation method of a copper-coated diamond-tin-based alloy composite material comprises the following steps: weighing 50-90 wt% of tin-based alloy powder and the balance of copper-coated diamond powder, uniformly mixing the tin-based alloy powder and the copper-coated diamond powder, and carrying out vacuum sintering under 10-25 MPa and 160-200 DEG C to prepare the copper-coated diamond-tin-based alloy composite material, the composite material is composed of a tin-based alloy continuous matrix and a copper-coated diamond reinforced phase uniformly dispersed in the matrix, and a multi-stage interface structure is formed around diamond particles. The copper plating layer is combined with the diamond core; the continuous copper-tin intermetallic compound transition layer is generated by reaction of copper and tin; and the tin-based alloy matrix is arranged in sequence from inside to outside. According to the method, the process controllability is high, interface bonding of the diamond and the tin-based alloy matrix can be effectively improved, and the prepared composite material is expected to have high heat conductivity, low thermal expansion coefficient and good mechanical property and is suitable for heat management and packaging of high-power electronic devices.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composite material preparation technology, and specifically to a method for preparing a diamond-tin-based alloy composite material with high thermal conductivity and low thermal expansion for use in electronic packaging. Background Technology

[0002] With the rapid development of fifth-generation mobile communication technology (5G), high-power lasers, advanced radar, and high-performance computing chips, electronic devices are evolving towards higher power density, higher integration, and miniaturization. This has led to increasingly severe heat accumulation problems during the operation of these devices, placing extremely stringent requirements on packaging and heat dissipation materials: they must possess extremely high thermal conductivity to quickly dissipate heat, while simultaneously having a low coefficient of thermal expansion that matches the semiconductor chip to reduce thermal stress, and maintaining sufficient strength and reliable sealing.

[0003] Tin-based alloys (such as Sn-Cu and Sn-Ag-Cu) are commonly used solders in electronic packaging due to their excellent solderability, good plasticity, and moderate cost. However, pure tin-based alloys have poor thermal conductivity (approximately 60-70 W / (m·K)) and a high coefficient of thermal expansion (approximately 22 × 10⁻⁶). -6 The thermal conductivity (W / (m·K)) of tin is insufficient to meet the heat dissipation requirements of high-power devices. Therefore, researchers often introduce reinforcing phases with high thermal conductivity and low thermal expansion (such as diamond, silicon carbide, and aluminum nitride) into the tin matrix to prepare metal-based composite materials. Among these, diamond stands out due to its extremely high thermal conductivity (~2000 W / (m·K)) and extremely low coefficient of thermal expansion (~1×10⁻⁶). -6 Diamond-tin composites ( / K) are considered ideal reinforcements. They can be used in critical heat dissipation areas of high-power devices, such as the thermal interface material between the chip and the heat sink, to achieve efficient thermal management of electronic devices.

[0004] However, when preparing diamond-tin-based alloy composites, the surface of diamond is composed of inert carbon atoms, which have extremely poor wettability with most metals (including tin). This results in weak bonding between the diamond and the matrix interface during the preparation process, with a large number of pores and defects. This will seriously reduce the thermal conductivity and mechanical properties of the composite material. Summary of the Invention

[0005] To address the common problems of weak interfacial bonding and difficulty in simultaneously achieving high thermal conductivity and high reliability in existing diamond / tin-based composite materials, the present invention aims to provide a copper-clad diamond / tin-based alloy composite material and its preparation method, thereby solving the core problem of poor thermal conductivity and reliability of composite materials due to weak interfacial bonding and uncontrollable structure, as described in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a copper-clad diamond-tin-based alloy composite material, comprising the following steps: S1. Weigh out tin-based alloy powder and copper-coated diamond powder, with the tin-based alloy powder content being 50 wt.% ~ 90 wt.% and the remainder being copper-coated diamond powder; S2. Mix the tin-based alloy powder and copper-coated diamond powder evenly; S3. The powder mixed uniformly in step S2 is placed in a vacuum hot pressing sintering furnace and vacuum sintered at a pressure range of 10 MPa to 25 MPa and a sintering temperature range of 160 to 200°C to prepare a copper-clad diamond-tin-based alloy composite material. The copper-clad diamond-tin-based alloy composite material is composed of a continuous tin-based alloy matrix and a copper-clad diamond reinforcing phase uniformly dispersed in the matrix. A multi-level interface structure is formed around the diamond particles, which consists of a diamond core, a copper plating layer bonded to the diamond core, a continuous copper-tin intermetallic compound transition layer generated by the reaction of copper and tin, and a tin-based alloy matrix, from the inside to the outside.

[0007] Furthermore, the tin-based alloy powder is one or more of the following: pure Sn, Sn-Cu alloy, Sn-Ag-Cu alloy, and Sn-Sb alloy.

[0008] Furthermore, the particle size of the tin-based alloy powder is 20-45 μm.

[0009] Furthermore, in the copper-coated diamond powder, the copper content is 20 wt.% to 60 wt.%, and the remainder is diamond content.

[0010] Furthermore, the diamond particle size of the copper-coated diamond powder is 30-50 μm.

[0011] Further, in step S2 above, tin-based alloy powder and copper-coated diamond powder are placed in the grinding jar of a ball mill, and grinding balls are added, and the mixture is stirred for 3-5 hours.

[0012] Furthermore, the vacuum sintering described in step S3 above involves maintaining a heating rate of 10-20 °C / min in the temperature range from room temperature to 120 °C, maintaining a heating rate of 5-10 °C / min in the temperature range from 120 °C to the sintering temperature, and holding the temperature and pressure at the sintering temperature for 5-15 min.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, through material design and control of the copper plating layer thickness and hot-pressing process parameters, adjusts the copper-tin interfacial reaction, forming a continuous and stable multi-level gradient interfacial structure between diamond and the substrate: "diamond-copper plating-copper-tin intermetallic compound (IMC)-tin-based alloy." This achieves a smooth transition in mechanical properties and thermal expansion coefficient from ultra-hard diamond to a soft tin alloy matrix. This structure allows for uniform distribution of diamond particles within the matrix, reducing interfacial thermal resistance and resulting in higher thermal conductivity in the composite material. The thermal expansion coefficient can also be adjusted by changing the diamond content. The use of copper-plated diamond in this invention not only reduces cost but also ensures good compatibility between copper and tin. The resulting continuous and appropriately thick copper-tin intermetallic compound layer achieves metallurgical bonding and regulates thermal mismatch.

[0014] The copper-clad diamond-tin-based alloy composite material prepared by the method of this invention has high thermal conductivity, adjustable low coefficient of thermal expansion, high density and good mechanical properties. It perfectly matches the stringent requirements of high power density electronic devices (such as CPU / GPU chips, IGBT modules, etc.) for packaging heat dissipation materials, and is one of the ideal candidate materials for the next generation of advanced thermal management systems. Attached Figure Description

[0015] Figure 1 The morphology of copper-coated diamond particles; Figure 2 The copper-clad diamond-tin-based alloy composite material prepared in Example 1; Figure 3 The SEM morphology of the copper-clad diamond-tin-based alloy composite material prepared in Example 1 is shown. Figure 4 The elemental distribution of the copper-clad diamond-tin-based alloy composite material prepared in Example 1 is shown below. Figure 5 This is a schematic diagram of the structure of copper-clad diamond-tin-based alloy composite material. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0017] This embodiment provides a method for preparing copper-clad diamond-tin-based alloy composite material, the steps of which are as follows: S1. Sn-0.3Ag-0.7Cu alloy powder with a particle size of 20-38 μm was selected; the diamond particles had a particle size of 40 μm, and the copper coating accounted for 50 wt.% of the total powder mass. Copper was deposited onto the surface of the diamond particles using existing chemical plating methods to prepare copper-coated diamond powder. Scanning electron microscopy (SEM) was used to observe the copper-coated diamond. Figure 1 As shown, the diamond particles are completely and uniformly coated with copper.

[0018] S2. Weigh out 70 wt.% Sn-0.3Ag-0.7Cu alloy powder and 30 wt.% copper-coated diamond powder by mass fraction. Place the Sn-0.3Ag-0.7Cu alloy powder and copper-coated diamond powder together with zirconia grinding balls (ball-to-powder ratio 2:1) in the ball mill jar and ball mill them together at 200 rpm for 4 hours.

[0019] S3. After the ball milling and mixing process, the resulting powder is loaded into a high-purity graphite mold and placed in a vacuum hot-pressing sintering furnace. A vacuum of 5 × 10⁻⁶ is then applied. -2 After Pa, heating and pressurization begin. The specific process is as follows: the temperature is increased from room temperature to 120℃ at a rate of 15℃ / min, and then increased to the target sintering temperature of 180℃ at a rate of 10℃ / min. During the heating process, pressure is applied when the temperature reaches 120℃, and the pressure is increased to 20 MPa when the temperature reaches 180℃. The temperature and pressure are held at 180℃ and 20 MPa for 10 minutes, then heating is stopped, and the furnace is cooled to room temperature. The high-purity graphite mold is then removed, and the finished product is taken out of the mold; this is the copper-clad diamond-tin-based alloy composite material. See [link to relevant documentation]. Figure 2 The composite material was observed using scanning electron microscopy (SEM), such as... Figure 3 As shown, diamond particles are uniformly distributed in the Sn-0.3Ag-0.7Cu matrix.

[0020] Energy dispersive spectroscopy (EDS) analysis was performed on copper-clad diamond-tin-based alloy composites, such as... Figure 4 As shown in Figure 4-1, the diamond particles are coated with copper and form an IMC transition layer with the tin alloy matrix. Figures 4-2, 4-3, 4-4, and 4-5 show the elemental distributions of C, Cu, Sn, and Ag, respectively.

[0021] Figure 5 The diagram schematically illustrates the structure of the copper-clad diamond-tin-based alloy composite material prepared by the method of this invention. Before sintering, from the inside out, the composite consists of a diamond core, a copper plating layer bonded to the diamond core, and a tin-based alloy matrix. After sintering, the copper-plated copper-clad diamond-tin-based alloy composite material is composed of a tin-based alloy matrix and a copper-clad diamond reinforcing phase uniformly dispersed in the matrix. A multi-level interface structure is formed around the diamond particles, from the inside out, consisting of a diamond core, a copper plating layer bonded to the diamond core, a continuous copper-tin intermetallic compound transition layer (IMC layer) formed by the reaction of copper and tin, and the tin-based alloy matrix.

[0022] The prepared copper-clad diamond-tin-based alloy composite material was tested and found to have a density of 97%, a thermal conductivity of 120 W / (m·K), and a coefficient of thermal expansion of 16 × 10⁻⁶. -6 / K. Example 2

[0023] This embodiment provides a method for preparing copper-clad diamond-tin-based alloy composite material, the steps of which are as follows: S1. Sn powder and Sn-0.3Sb powder are selected, with a powder particle size of 20-30μm; the diamond particle size is 30μm, and the copper coating accounts for 60 wt.% of the total powder mass. Copper is plated on the surface of the diamond particles by chemical plating to prepare copper-coated diamond powder.

[0024] S2. Weigh out 80 wt.% Sn powder, 10% Sn-0.3Sb powder, and 10 wt.% copper-coated diamond powder by mass fraction. Place the Sn powder, Sn-0.3Sb powder, and copper-coated diamond powder together with zirconia grinding balls (ball-to-material ratio 2:1) in the ball mill jar and ball mill them together at 100 rpm for 5 hours.

[0025] S3. After the ball milling and mixing process, the resulting powder is loaded into a high-purity graphite mold and placed in a vacuum hot-pressing sintering furnace. A vacuum of 5 × 10⁻⁶ is then applied. -2 After reaching the specified pressure (Pa), the heating and pressurization process begins. Specifically, the temperature is increased from room temperature to 120°C at a rate of 10°C / min, and then further increased to the target sintering temperature of 200°C at a rate of 5°C / min. During the heating process, pressure is applied when the temperature reaches 120°C, and reaches 10 MPa when the temperature reaches 200°C. The temperature and pressure are maintained at 200°C and 10 MPa for 15 minutes, after which heating is stopped, and the furnace is cooled to room temperature. The high-purity graphite mold is then removed, and the finished product is extracted, which is the copper-clad diamond-tin-based alloy composite material.

[0026] The prepared copper-clad diamond-tin-based alloy composite material was tested using standard methods, and its density was 98%, thermal conductivity was 85 W / (m·K), and coefficient of thermal expansion was 21 × 10⁻⁶. -6 / K. Example 3

[0027] This embodiment provides a method for preparing copper-clad diamond-tin-based alloy composite material, the steps of which are as follows: S1. Sn-0.7Cu powder with a particle size of 30-45μm is selected; the diamond particle size is 50μm; the copper coating accounts for 20 wt.% of the total powder mass; copper is plated on the surface of the diamond particles using the existing chemical plating method to prepare copper-coated diamond powder.

[0028] S2. Weigh out 50 wt.% Sn-0.7Cu powder and 50 wt.% copper-coated diamond powder by mass fraction. Place the Sn-0.7Cu powder and copper-coated diamond powder together with zirconia grinding balls (ball-to-powder ratio 2:1) in the ball mill jar and ball mill them together at 120 rpm for 3 hours.

[0029] S3. After the ball milling and mixing process, the resulting powder is loaded into a high-purity graphite mold and placed in a vacuum hot-pressing sintering furnace. A vacuum of 5 × 10⁻⁶ is then applied. -2 After Pa, heating and pressurization begin. The specific process is as follows: the temperature is increased from room temperature to 120℃ at a rate of 20℃ / min, and then increased to the target sintering temperature of 185℃ at a rate of 7℃ / min. During the heating process, pressure is applied when the temperature reaches 120℃, and the pressure is increased to 25 MPa when the temperature reaches 185℃. The temperature and pressure are held at 185℃ and 25 MPa for 15 minutes, then heating is stopped, and the furnace is cooled to room temperature. The high-purity graphite mold is then removed, and the finished product is taken out of the mold, which is the copper-clad diamond-tin-based alloy composite material.

[0030] The prepared copper-clad diamond-tin-based alloy composite material was tested using standard methods, and its density was 96%, thermal conductivity was 180 W / (m·K), and coefficient of thermal expansion was 10 × 10⁻⁶. -66 / K.

[0031] The ball mill, high-purity graphite mold, vacuum hot pressing sintering furnace, etc. used in the method of this invention are all existing technology equipment and devices.

[0032] Although the present invention has been described in detail above with general descriptions and specific embodiments, other embodiments are possible based on the scope defined by the claims, which will be obvious to those skilled in the art. Therefore, all other embodiments obtained without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a copper-clad diamond-tin-based alloy composite material, characterized in that, The steps are as follows: S1. Weigh out tin-based alloy powder and copper-coated diamond powder, with the tin-based alloy powder content being 50 wt.% ~ 90 wt.% and the remainder being copper-coated diamond powder; S2. Mix the tin-based alloy powder and copper-coated diamond powder evenly; S3. The powder mixed uniformly in step S2 is placed in a vacuum hot pressing sintering furnace and vacuum sintered at a pressure range of 10 MPa to 25 MPa and a sintering temperature range of 160 to 200°C to prepare a copper-clad diamond-tin-based alloy composite material. The copper-clad diamond-tin-based alloy composite material is composed of a continuous tin-based alloy matrix and a copper-clad diamond reinforcing phase uniformly dispersed in the matrix. A multi-level interface structure is formed around the diamond particles, which consists of a diamond core, a copper plating layer bonded to the diamond core, a continuous copper-tin intermetallic compound transition layer generated by the reaction of copper and tin, and a tin-based alloy matrix, from the inside to the outside.

2. The method for preparing a copper-clad diamond-tin-based alloy composite material according to claim 1, characterized in that, The tin-based alloy powder is one or more of the following: pure Sn, Sn-Cu alloy, Sn-Ag-Cu alloy, and Sn-Sb alloy.

3. The method for preparing a copper-clad diamond-tin-based alloy composite material according to claim 1 or 2, characterized in that, The particle size of the tin-based alloy powder is 20-45 μm.

4. The method for preparing a copper-clad diamond-tin-based alloy composite material according to claim 1, characterized in that, The copper-coated diamond powder contains 20 wt.% to 60 wt.% copper, with the remainder being diamond.

5. A method for preparing a copper-clad diamond-tin-based alloy composite material according to claim 1 or 4, characterized in that, The diamond particle size of the copper-coated diamond powder is 30-50 μm.

6. The method for preparing a copper-clad diamond-tin-based alloy composite material according to claim 1, characterized in that, Step S2 above involves placing tin-based alloy powder and copper-coated diamond powder into the grinding jar of a ball mill, adding grinding balls, and mixing for 3-5 hours.

7. The method for preparing a copper-clad diamond-tin-based alloy composite material according to claim 1, characterized in that, The vacuum sintering described in step S3 above involves maintaining a heating rate of 10-20 °C / min in the temperature range from room temperature to 120 °C, maintaining a heating rate of 5-10 °C / min in the temperature range from 120 °C to the sintering temperature, and holding the temperature and pressure at the sintering temperature for 5-15 min.

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