A method for preparing a superconducting hot diamond-copper composite foil

Abstract

This invention discloses a method for preparing a superconducting thermal diamond-copper composite foil, comprising the following steps: S1, purifying copper; S2, hot-rolling copper blocks into copper foil; S3, selecting diamond particles with a particle size of 0.05mm-0.1mm and modifying the surface of the diamond particles; S4, uniformly coating the modified diamond particles onto the surface of the copper foil, and then pressing the diamond particles onto the surface of the copper foil through hot pressing, so that the overall thickness of the Dia / Cu composite foil is 0.12mm-0.2mm; S5, heating the Dia / Cu composite foil in a vacuum environment; S6, heating the heated... S7. The diamond powder layer of the Dia / Cu composite foil is covered with a copper foil with a thickness of 0.08mm-0.15mm, and then the Cu / Dia / Cu composite foil is heated in a vacuum environment. S8. The heated Cu / Dia / Cu composite foil is subjected to vacuum hot pressing to make the thickness of the Cu / Dia / Cu composite foil 0.15mm-0.2mm. This can avoid the situation where the interfaces of the Dia / Cu composite foils are not wetted, resulting in high interfacial thermal resistance, thereby improving the thermal conductivity of the Dia / Cu composite foil.

Description

Technical Field

[0001] This invention relates to the field of thermal conductive materials technology, and in particular to a method for preparing a superconducting diamond-copper composite foil. Background Technology

[0002] As the integration scale of electronic components increases, the heat generated during circuit operation also rises accordingly, placing higher demands on the thermal conductivity of packaging materials that match integrated circuit chips. Theoretically, diamond / copper composites are well-suited for electronic packaging materials due to their comprehensive performance. However, in practice, the actual thermal conductivity of diamond / Cu composites in production is relatively low. This is mainly due to the immature processing technology and complex preparation process of diamond / copper composites. The main influencing factors are the intrinsic thermal conductivity of the copper matrix, the interfacial thermal conductivity, and the intrinsic thermal conductivity, volume fraction, and particle size of diamond. Generally, the lower the nitrogen content in diamond, the higher the thermal conductivity; the more complete the crystal form, the higher the thermal conductivity. Furthermore, the diamond surface is easily transformed into a graphite-like phase with poor thermal conductivity by high temperatures and catalytic elements, severely affecting the intrinsic thermal conductivity of diamond. Moreover, for the preparation of composite materials, mutual wetting between components is a necessary prerequisite for composite formation and a crucial factor affecting the interfacial structure and bonding state. The lack of wetting between diamond and Cu leads to high interfacial thermal resistance, thus affecting the thermal conductivity of the composite material.

[0003] Currently, the main technologies for preparing diamond / copper composites include high-temperature high-pressure sintering (HTHP), vacuum hot-pressing sintering (VHPS), spark plasma sintering (SPS), and melt infiltration. HTHP produces diamond / copper composites with high density, and the formed diamond framework facilitates thermal conductivity. However, HTHP requires extremely high-quality molds, resulting in small sample sizes and high costs, thus limiting its widespread application. VHPS is limited by mold requirements, with pressures generally below 100 MPa, resulting in limited improvement in the bonding between copper and diamond interfaces. It also demands high precision in controlling sintering parameters and selecting and adding active elements. VHPS has relatively low preparation efficiency, and preparing Dia / Cu with excellent thermal properties is quite difficult. Spark plasma sintering (SPPS) offers rapid heating and cooling, relatively low sintering temperatures, and high efficiency. Typically, the sintering temperature for Dia / Cu is 800–970℃, which does not exceed the melting point of copper. Within this temperature range, graphite molds are generally used for sintering. The fracture strength of graphite molds is less than 100 MPa, so the sintering pressure is generally 50–80 MPa. Within this pressure range, it is difficult for the composite material to become completely dense, and the internal porosity increases thermal resistance, reducing the thermal conductivity of Dia / Cu. Pressure infiltration is a complex process. The preparation of the reinforcing preform, the melting of the matrix, the gas flow during infiltration, and the solidification of the matrix all significantly affect the sample's performance. This method places high demands on the design of the graphite mold, the control of sintering parameters, and the selection of sintering equipment. Therefore, the preparation process of Dia / Cu requires further improvement. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the existing technology by providing a method for preparing a superconducting thermal diamond-copper composite foil, which can avoid the high interfacial thermal resistance caused by the non-wetting state of the Dia / Cu composite foil interface, thereby improving the thermal conductivity of the Dia / Cu composite foil.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a superconducting thermal diamond-copper composite foil includes the following steps:

[0007] S1. Purify copper to achieve a purity of over 99.99%;

[0008] S2. Hot-roll the copper block into copper foil with a thickness of 0.08mm-0.15mm;

[0009] S3. Select diamond particles with a particle size of 0.05mm-0.1mm and modify the surface of the diamond particles.

[0010] S4. The modified diamond particles are uniformly coated on the surface of the copper foil, and then the diamond particles are pressed onto the surface of the copper foil through hot pressing to form a diamond powder layer on the surface of the copper foil. The thickness of the overall Dia / Cu composite foil after hot pressing is 0.12mm-0.2mm.

[0011] S5. Place the Dia / Cu composite foil prepared in step S4 into a vacuum environment and heat it at a temperature of 1000-1050℃ for 8-10 minutes.

[0012] S6. The heated Dia / Cu composite foil is hot-pressed in a vacuum to make the overall thickness of the Dia / Cu composite foil 0.1mm-0.18mm.

[0013] S7. Cover the diamond powder layer of the Dia / Cu composite foil with a copper foil of 0.08mm-0.15mm thickness, and then place the Cu / Dia / Cu composite foil in a vacuum environment for heating.

[0014] S8. The heated Cu / Dia / Cu composite foil is hot-pressed in a vacuum to make the overall thickness of the Cu / Dia / Cu composite foil 0.15mm-0.2mm.

[0015] As a preferred option, in step S5, after the Dia / Cu composite foil is heated, a layer of modified diamond particles with a particle size of 0.02mm-0.05mm is uniformly coated on the surface of the diamond particle layer of the Dia / Cu composite foil.

[0016] As a preferred embodiment, in step S5, the heating temperature is 1000-1050℃, and the heating time is 8-10 minutes;

[0017] As a preferred embodiment, the following steps are also included:

[0018] S9. Seal the edges of the Cu / Dia / Cu composite foil.

[0019] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution, it mainly involves first modifying diamond particles, and then pressing the diamond particles onto the surface of a high-temperature copper foil through multiple vacuum hot pressing processes to produce a Cu / Dia / Cu composite foil. This composite foil avoids the situation where the interfaces of Dia / Cu composite foils are not wetted, which leads to high interfacial thermal resistance, thereby improving the thermal conductivity of Dia / Cu composite foils.

[0020] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the Dia / Cu composite foil after the first hot pressing according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the Dia / Cu composite foil after the second hot pressing according to an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure of the Cu / Dia / Cu composite foil after the third hot pressing according to an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0027] Please see Figures 1 to 4 This invention provides a method for preparing a superconducting thermal diamond-copper composite foil, characterized by comprising the following steps:

[0028] S1. Purify copper to achieve a purity of over 99.99%;

[0029] S2. The copper block is hot-rolled into copper foil with a thickness of 0.08mm-0.15mm. The copper block is melted at about 1200℃ and cast into ingots. The thickness of the copper alloy ingot is reduced by hot rolling. Specifically, the process is: melting → casting → hot rolling → cold rolling → annealing → cold rolling → degreasing → surface treatment.

[0030] S3. Select diamond particles with a particle size of 0.05mm-0.1mm and modify the surface of the diamond particles. Due to the low thermal expansion of diamond films and their difficulty in wetting and welding with metals, the assembly and application of diamond films with other devices and solders are greatly limited. Therefore, it is necessary to modify the diamond surface. Diamond particle surface metallization refers to the formation of a uniform metal or metal carbide layer on the surface of diamond particles by physical or chemical methods, so that the diamond particle surface has metallic or metal-like properties. In the preparation of composite materials, the diamond particles treated with surface metallization can change the direct contact between the copper matrix and the diamond to the contact between the metal or metal carbide layer, thereby achieving a tight bonding state at the interface and improving the thermal conductivity of the composite material. For example, plating active elements such as Mo, Ti, W, and Cr on the surface of the reinforcing phase can improve the diamond interface characteristics and thus improve its thermal conductivity. The thickness of the Cr plating layer is 0.2-8μm.

[0031] S4. The modified diamond particles are uniformly coated onto the surface of the copper foil, and then the diamond particles are pressed onto the copper foil surface through hot pressing. The temperature during hot pressing is 800-900℃, and the pressure is 80-120MPa; this forms a diamond powder layer on the surface of the copper foil. The overall thickness of the Dia / Cu composite foil after hot pressing is 0.12mm-0.2mm. In this step, it is easy to form... Figure 2 The discontinuous diamond powder layer shown affects the thermal conductivity of the composite foil.

[0032] S5. Place the Dia / Cu composite foil prepared in step S4 into a vacuum environment and heat it at a temperature of 1000-1050℃ for 8-10 minutes. The melting point of copper is 1083.4℃. The heating temperature makes the copper almost melt, softening the copper foil to facilitate the next step of hot pressing and impregnation.

[0033] S6. The heated Dia / Cu composite foil is hot-pressed in a vacuum to make the overall thickness of the Dia / Cu composite foil 0.1mm-0.18mm. The hot-pressing temperature is 800-900℃ and the pressure is 80-120MPa. The softened copper foil layer is then hot-pressed again to reduce the porosity of the Dia / Cu composite foil and lower the interfacial thermal resistance. Vacuum hot pressing has the advantages of uniform temperature, slow cooling rate, and can effectively reduce the thermal stress generated in the composite material during the hot pressing process. Moreover, the composition of the composite material is easier to control.

[0034] S7. Cover the diamond powder layer of the Dia / Cu composite foil with a copper foil of 0.08mm-0.15mm thickness, and then place the Cu / Dia / Cu composite foil in a vacuum environment and heat it at a temperature of 1000-1050℃ for 8-10 minutes.

[0035] S8. The heated Cu / Dia / Cu composite foil is hot-pressed in a vacuum to achieve an overall thickness of 0.15mm-0.2mm. The hot-pressing temperature is 800-900℃, and the pressure is 80-120MPa, forming a composite foil as shown in Figure 1. Figure 4 The Cu / Dia / Cu composite foil shown;

[0036] S9. Seal the edges of the Cu / Dia / Cu foil.

[0037] In this embodiment, in step S5, after the Dia / Cu composite foil is heated, a layer of modified diamond particles with a particle size of 0.02mm-0.05mm is uniformly coated on the surface of the diamond particle layer of the Dia / Cu composite foil. Figure 3 As shown, a diamond particle layer of a certain thickness is formed.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a superconducting thermal diamond-copper composite foil, characterized in that: Includes the following steps: S1. Purify copper to achieve a purity of over 99.99%; S2. Hot-roll the copper block into copper foil with a thickness of 0.08mm-0.15mm; S3. Select diamond particles with a particle size of 0.05mm-0.1mm and perform surface modification treatment on the diamond particles. The modification treatment is metallization modification. S4. The modified diamond particles are uniformly coated on the surface of the copper foil, and then the diamond particles are pressed onto the surface of the copper foil through hot pressing to form a diamond powder layer on the surface of the copper foil. The thickness of the overall Dia / Cu composite foil after hot pressing is 0.12mm-0.2mm. S5. Place the Dia / Cu composite foil prepared in step S4 into a vacuum environment and heat it at a temperature of 1000-1050℃ for 8-10 minutes. After the Dia / Cu composite foil is heated, a layer of modified diamond particles with a particle size of 0.02mm-0.05mm is uniformly coated on the surface of the diamond particle layer of the Dia / Cu composite foil. S6. The Dia / Cu composite foil obtained in step S5 is subjected to hot pressing in a vacuum to make the overall thickness of the Dia / Cu composite foil 0.1mm-0.18mm. S7. Cover the diamond powder layer of the Dia / Cu composite foil with a copper foil of 0.08mm-0.15mm thickness, and then place the Cu / Dia / Cu composite foil in a vacuum environment for heating. S8. The heated Cu / Dia / Cu composite foil is hot-pressed in a vacuum to make the overall thickness of the Cu / Dia / Cu composite foil 0.15mm-0.2mm.

2. The method for preparing a superconducting thermal diamond-copper composite foil according to claim 1, characterized in that: It also includes the following steps: S9. Seal the edges of the Cu / Dia / Cu composite foil.

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