A multi-layer through-hole coaxial alignment diamond particle reinforced copper-based composite material

Abstract

This invention discloses a multi-layered, coaxially aligned diamond particle-reinforced copper-based composite material and its preparation method. The method includes forming a uniform array of V-shaped through-holes on a copper foil using laser processing, mechanical punching, or etching to obtain a copper foil template; embedding diamond particles into the V-shaped through-holes on the copper foil template skeleton; stacking multiple layers of the copper foil template skeleton through interlayer alignment and filling the interlayer gaps with copper powder to form a diamond / copper skeleton preform; and densifying the preform to finally obtain a composite material with preferential thermal conductivity channels in the thickness direction. This invention effectively solves the problems of low out-of-plane thermal conductivity, easy particle agglomeration, and poor structural integrity in copper and diamond composite materials. Furthermore, it allows for array densification or gradient aperture design to optimize heat flow paths according to application requirements.

Description

Technical Field

[0001] This invention relates to the field of diamond composite materials technology, and in particular to a composite material and its preparation method for achieving an out-of-plane high thermal conductivity structure by using a template to construct a diamond array and combining it with copper multilayer metallurgy. Background Technology

[0002] With the rapid development of modern electronic information technology towards high frequency, high power, high integration, and miniaturization, the heat density of high-power electronic devices (such as IGBT modules and third-generation semiconductor chips) is increasing dramatically during operation. If this heat cannot be dissipated in time, it will seriously affect the lifespan and reliability of the devices. Diamond has extremely high thermal conductivity (up to approximately 2000 W / m·K at room temperature), while copper has excellent thermal conductivity and processing properties. Therefore, diamond / copper-based composite materials are considered to be a highly promising next-generation heat dissipation material for electronic packaging.

[0003] However, existing diamond / copper matrix composites and their preparation technologies still face the following significant technical bottlenecks.

[0004] First, the traditional powder metallurgy method (which involves directly mixing diamond particles with copper powder and then sintering) is widely used in industry. This method results in a disordered, random, and isotropic distribution of diamond particles within the matrix. Since chip heating typically exhibits surface heat source characteristics, its heat dissipation path mainly depends on the thickness direction (Z-axis direction) of the material. Disordered particles cannot form continuous and efficient heat flow channels in the thickness direction. At the same time, random distribution easily leads to the agglomeration of diamond particles at high volume fractions, increasing phonon scattering of heat at the interface and significantly weakening the actual thermal conductivity of the composite material.

[0005] Secondly, to improve thermal conductivity directionality, some existing technologies attempt to use porous metals (such as copper foam) as a supporting framework combined with diamond for layered sintering. While this method provides macroscopic support to some extent, the pores in porous copper foam are highly random, making it impossible to achieve precise positioning and array arrangement of diamond particles; moreover, the lack of effective physical restraint structures makes it easy for particles to slip or fall off during subsequent compression molding. In addition, simple interlayer stacking without effective densification filling methods can easily generate interfacial micropores within the material. Under repeated thermal cycling and thermal shock, the structural integrity of the material is easily damaged, leading to a decrease in thermal conductivity or even material cracking.

[0006] In summary, the current field urgently needs a composite material structure and its preparation method that can precisely control the spatial distribution of diamond, forcibly construct continuous high thermal conductivity channels in the thickness direction, and possess excellent structural integrity and mechanical stability. Summary of the Invention

[0007] To address the shortcomings of the existing technologies, the present invention aims to provide a multi-layered, coaxially aligned diamond particle-reinforced copper matrix composite material and its preparation method, thereby solving the problems of low out-of-plane thermal conductivity, poor structural integrity, and difficulty in precisely controlling the spatial distribution of diamond in existing diamond / copper composite materials.

[0008] To achieve the above objectives, the primary technical solution of this invention is to provide a multi-layered, coaxially aligned, diamond particle-reinforced copper-based composite material. The material comprises a multi-layered, through-hole copper foil skeleton and uniformly arrayed diamond particles. The copper foil skeleton is stacked along its thickness direction, and has arrayed through-holes. Each through-hole has a V-shaped structure, wider at the top and narrower at the bottom, in the thickness direction, with the diamond particles correspondingly embedded within them. The upper opening diameter of the V-shaped structure is larger than the lower opening diameter, and the lower opening diameter is smaller than the minimum particle size of the diamond particles. The three-dimensional morphology of the V-shaped structure is a frustum or inverted frustum-shaped hole with a V-shaped cross-section, forming a physical barrier. Copper powder is filled between each layer of the copper foil skeleton to maintain the overall structural integrity. The diamond penetration direction of the composite material is consistent with the thickness direction of the composite material, forming a preferential heat-conducting channel in the thickness direction of the multiple layers.

[0009] Furthermore, the extension direction of the preferred heat conduction channel is parallel to the thickness direction of the composite material.

[0010] To achieve the above objectives, the technical solution of the present invention is to provide a method for preparing the above-mentioned multi-layered through-hole coaxially aligned diamond particle-reinforced copper-based composite material, comprising the following steps:

[0011] (1) Material preparation: Prepare the diamond particles, copper foil and copper powder;

[0012] (2) Copper foil processing: A V-shaped structure with a wider top and narrower bottom and conforming to the diamond particle size is processed on the copper foil in an array arrangement by means of laser processing, mechanical punching or etching, etc., and a through hole is formed. The copper foil is then deoxidized to obtain a copper foil template.

[0013] (3) Preform preparation: The diamond particles are embedded in the V-shaped through holes of the copper foil template, and the copper foil templates with multiple layers of diamond particles are stacked and aligned between layers. The copper powder is filled in the gaps between the copper foil layers to form a diamond / copper skeleton preform.

[0014] (4) Sintering and post-treatment: The diamond / copper skeleton preform is subjected to vacuum hot pressing sintering or pressure melting densification, and after demolding, it is polished to obtain the diamond particle reinforced copper matrix composite material with coaxial alignment of multi-layer through holes.

[0015] Furthermore, in step (2), the through hole is formed by laser processing, mechanical punching or etching.

[0016] Furthermore, in step (3), the coaxial alignment is achieved through positioning holes or positioning pins.

[0017] The beneficial effects of this invention are:

[0018] By constructing a Z-axis priority heat conduction channel, targeted heat dissipation efficiency can be greatly improved. This invention overcomes the disordered distribution defects caused by traditional powder mixing. Through a copper foil skeleton with arrayed through holes, diamond particles are precisely arrayed and aligned in space. This structure ensures that the through-hole direction of the diamond is highly consistent with the thickness direction (main heat transfer direction) of the composite material, forcibly constructing a longitudinally continuous and efficient heat flow channel, significantly reducing interfacial thermal resistance and phonon scattering, and significantly improving the thermal conductivity of the material in the thickness direction.

[0019] The designed V-shaped hole, wider at the top and narrower at the bottom, maximizes self-locking and thermal contact. The copper foil through-hole of this invention is uniquely designed with a V-shaped structure, wider at the top and narrower at the bottom, in the thickness direction. On one hand, this structure creates a physical self-locking effect on the embedded diamond particles, effectively preventing particle detachment or slippage during subsequent processes and service, ensuring extremely high stability of the array arrangement. On the other hand, the V-shaped bevel significantly increases the contact area between the diamond particles and the pure copper foil skeleton, further optimizing the thermal conductivity of the interface.

[0020] The synergy between the copper foil skeleton and the interlayer copper powder ensures the integrity of the macroscopic structure. Addressing the weaknesses of traditional laminated structures, such as weak interfacial bonding and susceptibility to cracking, this invention uses a high thermal conductivity continuous copper foil as the main skeleton, and fills the gaps between the layers with copper powder through hot pressing sintering or melt infiltration. This composite structure minimizes interlayer porosity during densification, forming a metallurgical bond. While maintaining longitudinal thermal conductivity channels, it significantly improves the overall structural strength, thermal shock resistance, and mechanical processing properties of the composite material. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the metal matrix composite material with diamond array-copper-based thermal conductive channels of the present invention;

[0022] Figure 2 This is a schematic diagram of a single-layer diamond / copper framework structure;

[0023] Figure 3 This is a schematic diagram of the cross-sectional structure of a diamond / copper matrix laminate;

[0024] Figure 4 This is a schematic diagram of the pressure mold cavity structure;

[0025] Figure 5 This is an actual SEM image of a diamond particle-reinforced copper matrix composite sample with multi-layered through-hole coaxial alignment.

[0026] Figure 6 This is a flowchart illustrating the preparation process of the multilayer through-hole coaxial aligned diamond particle reinforced copper-based composite material of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention. To make the objectives, features and advantages of the present invention more apparent and understandable, please refer to the accompanying drawings. It should be understood that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship or adjustment of the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0028] Example 1 (Optimal Parameter Combination)

[0029] A method for preparing a multilayered, coaxially aligned diamond particle-reinforced copper matrix composite material. Diamond with an average particle size of 300 μm and a volume fraction of 30% is selected. Pure copper foil is etched and perforated using an infrared laser drilling machine in an argon atmosphere. By controlling the laser energy distribution, V-shaped through-holes with a wider upper opening and a narrower lower opening (upper opening diameter approximately 320 μm, lower opening diameter approximately 290 μm) are obtained in the thickness direction. Subsequently, an oxidation removal treatment is performed to obtain a copper foil template. The diamond is embedded into the V-shaped hole array of the template through mechanical vibration to achieve self-locking. The diamond-embedded copper foil and blank template are alternately stacked, and positioning pins are used to ensure cross-layer alignment. Spherical pure copper powder with a particle size of 1-5 μm is filled into the interlayer gaps of the diamond / copper framework preform, and ultrasonic vibration is used to ensure tight filling. Finally, under a vacuum of less than 10 Pa, a rapid hot-pressing sintering process was used to raise the temperature to 800 °C at a rate of 100 °C / min, and then sintered at 20 MPa for 10 minutes, followed by furnace cooling. Tests showed that the composite material was dense and pore-free, with an in-plane thermal conductivity of 484 W / (m·K) and an out-of-plane (Z-axis thickness direction) thermal conductivity as high as 688 W / (m·K).

[0030] Example 2 (low volume fraction)

[0031] The preparation method was the same as in Example 1, except that the volume fraction of diamond was 10%. After cooling and demolding, the composite material was tested and found to be dense, with an in-plane thermal conductivity of 450 W / (m·K) and an out-of-plane thermal conductivity of 597 W / (m·K).

[0032] Example 3 (Medium volume fraction)

[0033] The preparation method was the same as in Example 1, except that the volume fraction of diamond was 20%. After cooling and demolding, the composite material was tested and found to be dense, with an in-plane thermal conductivity of 470 W / (m·K) and an out-of-plane thermal conductivity of 632 W / (m·K).

[0034] Example 4 (Loose Array Arrangement)

[0035] The preparation method is the same as in Example 1, except that a loose array arrangement is used during laser etching and drilling to increase the hole spacing, thereby reducing the equivalent volume fraction of diamond in this area to about 15%. After cooling and demolding, the in-plane thermal conductivity is 455 W / (m·K) and the out-of-plane thermal conductivity is 610 W / (m·K), indicating good material density.

[0036] Example 5 (Local High-Density Array Arrangement)

[0037] The preparation method is the same as in Example 1, except that during laser etching and drilling, a high-density array arrangement (reducing the hole spacing) is used in the corresponding local area according to the heat dissipation requirements of the chip hot spot area, thereby increasing the diamond equivalent volume fraction of the local densified area to about 35%. After cooling and demolding, the in-plane thermal conductivity of the local densified area was measured to be 495 W / (m·K), and the out-of-plane thermal conductivity was increased to 735 W / (m·K), which can effectively achieve rapid temperature uniformity and targeted heat conduction for local hot spots.

[0038] Comparative Example 1 (Compared to traditional powder mixing method)

[0039] Diamond particles (300 μm in diameter, 30% by volume) identical to those used in Example 1 and spherical pure copper powder were selected. Without any copper foil template preparation or array arrangement, the diamond particles and copper powder were directly mechanically mixed uniformly using a three-dimensional mixer. Subsequently, a hot-pressing sintering process identical to that in Example 1 was employed (vacuum <10 Pa, 800 °C, 20 MPa, holding for 10 min). The in-plane thermal conductivity of this comparative example was measured to be 380 W / (m·K), and the out-of-plane thermal conductivity was 390 W / (m·K). It is evident that due to the lack of high thermal conductivity array channels in the thickness direction, heat transfer in all directions is severely hindered by interface phonon scattering, especially the out-of-plane (Z-axis) thermal conductivity, which is far lower than the 688 W / (m·K) of Example 1 of this invention.

[0040] Comparative Example 2 (Verifying the effect of the V-shaped self-locking hole)

[0041] The same materials as in Example 1 were selected. However, during the processing of the copper foil, mechanical drilling was used instead of laser etching to form straight cylindrical holes with consistent top and bottom diameters (approximately 310 μm), lacking the V-shaped self-locking structure that is wider at the top and narrower at the bottom. During the lamination process, the same process as in Example 1 was used, filling the interlayer gaps with pure copper powder. The same hot-pressing sintering was then performed. SEM images of the cross-section after demolding showed that, due to the lack of the self-locking effect of the V-shaped holes, some diamond particles slightly slipped and displaced during the pressing process, and the effective contact area between the particles and the pure copper foil skeleton was reduced. The in-plane thermal conductivity of this comparative example was measured to be 460 W / (m·K), and the out-of-plane thermal conductivity was 580 W / (m·K). This result demonstrates that although straight cylindrical holes can provide a certain spatial heat conduction channel, the lack of the physical locking and increased contact area effect of V-shaped holes prevents the maximization of interfacial thermal conductivity and array stability.

[0042] Comparative Example 3 (Verification of the densification effect of pure copper powder in the interlayer)

[0043] The same material as in Example 1 was selected, and a copper foil template with a V-shaped through-hole (wider at the top, narrower at the bottom) was prepared using laser etching. However, during the lamination process, only the diamond-embedded copper foil templates were directly stacked between layers without filling the interlayer gaps with pure copper powder. The same hot-pressing sintering was then performed. After demolding, microcracks were found at the edges of the composite material; cross-sectional SEM showed obvious microscopic voids and partial debonding between the diamond / copper framework layers, failing to achieve a completely dense metallurgical bond. The in-plane thermal conductivity was measured to be 410 W / (m·K), and the out-of-plane thermal conductivity was 510 W / (m·K). This result demonstrates that the lack of densification with pure copper powder not only leads to a sharp increase in interfacial thermal resistance but also makes the material highly susceptible to stress concentration during hot pressing, resulting in the collapse of the composite material's macroscopic structural integrity and mechanical stability.

[0044] Comparative Example 4 (verifying the limitations of high volume fraction)

[0045] The preparation method is the same as in Example 1, except that the volume fraction of diamond is forcibly increased to 40%. The measured in-plane thermal conductivity is 485 W / (m·K), and the out-of-plane thermal conductivity reaches 690 W / (m·K). However, due to the excessively high diamond volume fraction, exceeding the limit of complete metallurgical bonding achievable by the copper-based framework and copper powder filler, the composite material exhibits macroscopically loose structures in some areas. In subsequent simulated thermal cycling impact tests, this comparative example is highly susceptible to cracking failure due to the propagation of interface defects. This further demonstrates the scientific validity and necessity of strictly limiting the diamond volume fraction to the range of 10%-30% in the claims of this invention.

[0046] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

[0047] 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.

[0048] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope 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 the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A multi-layered, coaxially aligned, diamond particle-reinforced copper-based composite material, characterized in that, The composite material comprises a copper foil skeleton with multiple layers of through holes and diamond particles arranged in a uniform array. The copper foil skeleton is stacked along its thickness direction and has an array of through holes. The through holes have a V-shaped structure that is wider at the top and narrower at the bottom in the thickness direction, and the diamond particles are embedded in the through holes. The upper opening diameter of the V-shaped structure is larger than the lower opening diameter, and the lower opening diameter is smaller than the minimum particle size of the diamond particles. The three-dimensional shape of the V-shaped structure is a frustum or inverted frustum-shaped hole with a V-shaped cross-section to form a physical barrier. Copper powder is filled between each layer of the copper foil skeleton to maintain the overall structural integrity. The diamond penetration direction of the composite material is consistent with the thickness direction of the composite material to form a preferential heat conduction channel in the thickness direction of multiple layers.

2. The composite material according to claim 1, characterized in that, The extension direction of the preferred heat conduction channel is parallel to the thickness direction of the composite material.

3. A method for preparing a multilayered, coaxially aligned diamond particle-reinforced copper-based composite material, characterized in that, Includes the following steps: (1) Material preparation: Prepare the diamond particles, copper foil and copper powder; (2) Copper foil processing: A V-shaped structure with a wider top and narrower bottom and conforming to the diamond particle size is processed on the copper foil in an array arrangement by means of laser processing, mechanical punching or etching, etc., and a through hole is formed. The copper foil is then deoxidized to obtain a copper foil template. (3) Preform preparation: The diamond particles are embedded in the V-shaped through holes of the copper foil template, and the copper foil templates with multiple layers of diamond particles are stacked and aligned between layers. The copper powder is filled in the gaps between the copper foil layers to form a diamond / copper skeleton preform. (4) Sintering and post-treatment: The diamond / copper skeleton preform is subjected to vacuum hot pressing sintering or pressure melting densification, and after demolding, it is polished to obtain the diamond particle reinforced copper matrix composite material with coaxial alignment of multi-layer through holes.

4. The method according to claim 3, characterized in that, The through hole is formed by laser processing, mechanical punching, or etching.

5. The method according to claim 3, characterized in that, The coaxial alignment is achieved through positioning holes or positioning pins.

6. The method according to claim 3, characterized in that, The densification process is performed by hot pressing, hot isostatic pressing, diffusion welding, or pressure infiltration.

7. The method according to claim 3, characterized in that, Each of the through holes contains only one diamond particle.

8. The method according to claim 3, characterized in that, The diameter of the through hole is between 50 micrometers and 500 micrometers.

9. The composite material according to claim 3, characterized in that, The volume fraction of the diamond particles is 10%-30%.

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