A composite radiator and its application

Abstract

This invention discloses a composite heat sink and its application. The composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. Both the base plate and the heat dissipation fins are made of an aluminum-based composite material, which includes an aluminum matrix and graphite. The composite heat sink provided by this invention is made of an aluminum-based composite material, which is composed of an aluminum matrix and graphite. The resulting heat sink has an in-plane thermal conductivity of up to 300 W / m·K and a density of less than 2.5 g / cm³. 3 It can simultaneously achieve good heat dissipation, light weight, low thermal resistance, and low production cost.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation devices, and in particular to a composite heat sink and its application. Background Technology

[0002] With the rapid development of high technology, electronic components are becoming increasingly smaller and denser per unit area, while their efficiency remains high. As a result, the total heat generated by electronic components is increasing almost year by year. To ensure the normal operation of electronic components, heat sinks need to be installed to dissipate heat and prevent certain electronic components from operating at high temperatures, thus shortening their lifespan.

[0003] In existing technologies, heat sinks generally consist of two parts: the base plate and the heat dissipation fins. The base plate is where the heat comes into contact with electronic components and accumulates heat, while the heat dissipation fins are the endpoints of heat conduction, ultimately dissipating heat into the air. This type of heat sink primarily relies on heat conduction for heat dissipation, thus requiring a large surface area and a high thermal conductivity. The performance of a heat sink is not only related to its structure but also determined by the choice of materials, which refers to the specific materials used in the heat sink body.

[0004] Currently, there are three main types of heat sink materials: (1) Pure aluminum heat sink: The base plate and heat sink fins of the heat sink are made of pure aluminum or 6063 alloy. Both of these materials have good thermal conductivity, and the industrial thermal conductivity can reach about 200W / m·K; (2) Pure copper heat sink: The base plate and heat sink fins of the heat sink are made of pure copper. The heat transfer coefficient of copper can reach 400W / m·K, which can significantly improve the heat transfer efficiency; (3) Copper-aluminum composite heat sink: The base plate of the heat sink is made of pure copper, and the heat sink fins are made of aluminum alloy.

[0005] However, in the process of implementing the embodiments of this application, the inventors of this application discovered that the above-mentioned technology has at least the following technical problems: pure aluminum heat sinks cannot meet the heat dissipation requirements of electronic components with continuously increasing heat generation, and the heat dissipation function is large in size; pure copper heat sinks are heavy and expensive, which is not conducive to widespread application; poor connection between the copper base plate and the aluminum fins of the copper-aluminum composite heat exchanger will produce a large contact thermal resistance, affecting the heat dissipation effect.

[0006] Therefore, providing a heat sink that has good heat dissipation performance, is lightweight, has low thermal resistance, and has low production cost has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The main objective of this invention is to propose a composite radiator and its application, which solves the technical problem that existing radiators are difficult to simultaneously achieve good heat dissipation, light weight, low thermal resistance, and low production cost.

[0008] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0009] In one aspect of the invention, a composite heat sink is provided, comprising a base plate and heat dissipation fins disposed on the base plate, wherein both the base plate and the heat dissipation fins are made of an aluminum-based composite material, the aluminum-based composite material comprising an aluminum matrix and graphite.

[0010] Optionally, the aluminum matrix is ​​aluminum or an aluminum alloy; the raw material for the aluminum matrix is ​​aluminum matrix powder.

[0011] Optionally, the average particle size of the aluminum matrix powder is 1-100 μm.

[0012] Optionally, the aluminum matrix powder is prepared by gas atomization.

[0013] Optionally, the thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm.

[0014] Optionally, the graphite surface is covered with a coating, the coating material being silicon or a metal material; the thickness of the coating is 100-200 μm.

[0015] Optionally, the graphite is flake graphite.

[0016] Optionally, the diameter of the flake graphite is 150-1000 μm and the thickness is 10-50 μm.

[0017] Optionally, the planar direction of the flake graphite in the base plate is parallel to the direction of heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of heat flow through the heat dissipation fins.

[0018] Optionally, the preparation method of the aluminum-based composite material includes the following steps:

[0019] Provide aluminum matrix powder;

[0020] The aluminum matrix powder is mixed evenly with graphite to obtain a mixture;

[0021] The mixture is poured into a mold and repeatedly shaken.

[0022] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0023] Optionally, in the mixture, the volume fraction of graphite is 20-75 vol%, with the remainder being aluminum matrix powder.

[0024] Optionally, a groove is formed on one side of the base plate, and one end of the heat dissipation fin is embedded in the groove and welded to the base plate.

[0025] In another aspect, the present invention provides the application of the above-described composite heat sink in high-power heat-generating electronic devices.

[0026] The present invention has the following beneficial effects:

[0027] The composite radiator provided by this invention is made of aluminum-based composite material, which is composed of an aluminum matrix and graphite. The resulting radiator has an in-plane thermal conductivity of up to 300 W / m·K and a density of less than 2.5 g / cm³. 3 It can simultaneously achieve good heat dissipation, light weight, low thermal resistance, and low production cost.

[0028] The significant density difference between graphite and the aluminum matrix results in poor interfacial wettability, hindering graphite dispersion and causing poor compatibility. Furthermore, the interfacial reaction between graphite and aluminum is difficult to control, easily forming intermetallic compounds that generate significant thermal resistance at the interface. This prevents the full utilization of graphite's high thermal conductivity, thus affecting the overall thermal conductivity. To address these issues, this invention controls the oxide film thickness on the aluminum matrix powder surface to be less than 4 nm and applies a coating to the graphite surface. These combined actions improve the wettability between graphite and the aluminum matrix, enhance their compatibility, prevent undesirable interfacial reactions between carbon and aluminum, reduce interfacial thermal resistance, and ultimately improve the thermal conductivity of the aluminum-based composite material.

[0029] Artificially synthesized flake graphite has a thermal conductivity of 1200-1800 W / m·K along its planar direction and has been successfully mass-produced. However, the thermal conductivity of flake graphite perpendicular to this planar direction is extremely low, only 10-20 W / m·K, which greatly affects heat dissipation. To solve this problem, in this invention, the planar direction of the flake graphite in the base plate is parallel to the direction of heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of heat flow through the heat dissipation fins. By controlling the orientation of the flake graphite in the base plate and heat dissipation fins, this invention ensures that the orientation direction of the flake graphite is consistent with the direction of heat flow, thus fully utilizing the high thermal conductivity of the planar direction of the flake graphite to achieve a good heat dissipation effect.

[0030] The composite heat sink of the present invention can be applied to various electronic components, which can improve the heat dissipation efficiency of electronic components, improve the reliability of electronic components, and help extend the service life of electronic components. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the composite heat sink according to Embodiment 1 of the present invention;

[0033] Figure 2 This is a schematic diagram of the composite heat sink according to Embodiment 3 of the present invention.

[0034] Explanation of icon numbers:

[0035] label name label name 1 flake graphite 2 Aluminum base 3 base plate 4 Heat dissipation fins Detailed Implementation

[0036] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0037] Unless otherwise specified, the terms used in this specification have the same meaning as those commonly understood by those skilled in the art; however, in the event of any conflict, the definitions in this specification shall prevail.

[0038] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The term “comprising” also includes the terms “consisting of” and “substantially consisting of”. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein.

[0039] All numerical values ​​or expressions relating to component amounts, process conditions, etc., used in the specification and claims are to be understood to be modified with “about” in all cases. All ranges relating to the same component or property include endpoints that can be independently combined. Because these ranges are continuous, they include every value between the minimum and maximum values. It should also be understood that any numerical range referenced in this application is intended to include all subranges within that range.

[0040] As described in the background section, existing technologies suffer from the problem that heat sinks cannot simultaneously achieve good heat dissipation, light weight, low thermal resistance, and low production cost. To address these issues, this invention provides a composite heat sink and its application.

[0041] In a first aspect, a composite heat sink includes a base plate and heat dissipation fins disposed on the base plate, wherein both the base plate and the heat dissipation fins are made of an aluminum-based composite material, the aluminum-based composite material comprising an aluminum matrix and graphite.

[0042] In this invention, the aluminum matrix is ​​aluminum or an aluminum alloy. For the aluminum alloy, the specific composition is not particularly limited, but preferably, the aluminum alloy is 3003 or 6063.

[0043] In aluminum-based composites, the aluminum matrix serves two purposes: as a thermally conductive matrix and as a binder and fixator for graphite. As a traditional thermally conductive material, the aluminum matrix possesses good thermal conductivity and high strength. Combining it with highly thermally conductive graphite can further improve the thermal conductivity of the aluminum-based composite.

[0044] The composite heat sink of the present invention does not require the use of a fan for forced convection, but can dissipate heat through natural air convection, thus having the characteristics of being noiseless and dust-free.

[0045] The composite heat sink of the present invention has an in-plane thermal conductivity of up to 300 W / m·K, and can be applied to various electronic components. It can improve the heat dissipation efficiency of electronic components, improve the reliability of electronic components, and help extend the service life of electronic components.

[0046] In this invention, the raw material for the aluminum matrix is ​​aluminum matrix powder.

[0047] In this invention, the average particle size of the aluminum matrix powder is 1-100 μm, for example, 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm and any value between them.

[0048] In this invention, the aluminum matrix powder is prepared by gas atomization.

[0049] This invention does not impose any particular limitations on the specific process and conditions for preparing aluminum matrix powder using the gas atomization method. The conventional gas atomization process described above, well-known to those skilled in the art, can be used. Those skilled in the art can select and adjust the process according to actual production conditions, product requirements, and quality requirements. Preferably, the method for preparing the aluminum matrix powder is as follows: using high-pressure gas as the atomizing medium to break up the molten aluminum matrix stream to obtain aluminum matrix powder. The aluminum matrix powder is a smooth sphere, and the cooling rate is 100℃ / s. The high-pressure gas includes nitrogen and oxygen with a purity of 99.9% or higher, wherein the volume content of the oxygen is 0.05-1.5%.

[0050] In this invention, the thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm. This avoids the formation of micropores that could affect the sintering effect and reduce heat transfer performance and strength.

[0051] In this invention, the graphite surface is covered with a coating. This reduces the surface energy between the two phases, decreases porosity, and prevents the formation of Al-C compounds during the heating and melting process, which would otherwise create thermal resistance and reduce thermal conductivity.

[0052] In this invention, the material of the coating is not particularly limited, as long as it can achieve the above-mentioned function. Preferably, the material of the coating is silicon or metal, and more preferably, the material of the coating is silicon.

[0053] In this invention, the thickness of the coating is 100-200μm, for example 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm and any value between them.

[0054] In this invention, the preparation method for the graphite surface covered with a coating is not particularly limited; any conventional coating preparation process well-known to those skilled in the art is acceptable. Those skilled in the art can select and adjust the method according to actual production conditions, product requirements, and quality requirements. Taking a graphite surface covered with a silicon layer as an example, the preparation method is as follows: Cleaned and dried graphite is mixed evenly with anhydrous calcium chloride powder and silicon powder, and then placed in a crucible. The mixture is then heated in a vacuum carbon tube furnace according to a pre-set heating program to 1200°C, held at that temperature for 2 hours. After the carbon tube furnace heating and holding program is completed, the furnace body is allowed to cool naturally to room temperature, and the blended powder is removed. The blended powder is then washed with hot water to dissolve the calcium chloride. The mass ratio of graphite to anhydrous calcium chloride powder is 1:1, the mass ratio of graphite to silicon powder is 6-8:1, and the diameter of the silicon powder is less than 20 μm.

[0055] The inventors discovered in practice that the significant density difference between graphite and the aluminum matrix results in poor interfacial wettability, preventing graphite from dispersing properly within the aluminum matrix and leading to poor compatibility between the two materials. Furthermore, the interfacial reaction between graphite and the aluminum matrix is ​​difficult to control, easily forming intermetallic compounds that generate significant thermal resistance at the interface, thus hindering the full utilization of graphite's high thermal conductivity and affecting its thermal conductivity. To address these issues, this invention controls the oxide film thickness on the aluminum matrix powder surface to be less than 4 nm and applies a coating to the graphite surface. These combined actions improve the wettability between graphite and the aluminum matrix, enhance their compatibility, prevent undesirable interfacial reactions between carbon and aluminum, reduce interfacial thermal resistance, and ultimately improve the thermal conductivity of the aluminum-based composite material.

[0056] Graphite can be classified into four main morphologies: flake graphite, spheroidal graphite, vermicular graphite, and nodular graphite. In this invention, the graphite is preferably flake graphite. The flake graphite has a diameter of 150-1000 μm and a thickness of 10-50 μm.

[0057] In this invention, the planar direction of the flake graphite in the base plate is parallel to the direction of heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of heat flow through the heat dissipation fins.

[0058] It should be noted that in this invention, the electronic component is in contact with the base plate and is located at the center of the base plate. The heat flow path is as follows: the heat generated by the electronic component is conducted to the left and right sides of the electronic component through the base plate, and the base plate then conducts the heat flow to the heat dissipation fins for heat dissipation.

[0059] Graphite, a domestically abundant and inexpensive material, is an allotrope of carbon, belonging to the hexagonal crystal system. Each carbon atom within a sheet is covalently bonded to three other carbon atoms, arranged in a honeycomb pattern of multiple hexagonal shapes. The sheets are connected by van der Waals forces, giving it many anisotropic properties. Graphite also possesses lightweight properties (density ~2.26 g·cm⁻³), good high-temperature resistance, thermal shock resistance, and corrosion resistance. Artificially synthesized flake graphite has a thermal conductivity of 1200-1800 W / m·K along its planar direction and has been successfully mass-produced. However, the thermal conductivity of flake graphite perpendicular to its planar direction is extremely low, only 10-20 W / m·K, significantly affecting heat dissipation. To address this issue, in this invention, the planar direction of the flake graphite in the base plate is parallel to the direction of heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of heat flow through the heat dissipation fins. This invention controls the orientation of the flake graphite in the base plate and heat dissipation fins so that the orientation direction of the flake graphite is consistent with the direction of heat flow. This fully utilizes the high thermal conductivity of the flake graphite in the planar direction to achieve a good heat dissipation effect.

[0060] The preparation method of the aluminum-based composite material in this invention includes the following steps:

[0061] Provide aluminum matrix powder;

[0062] The aluminum matrix powder is mixed evenly with graphite to obtain a mixture;

[0063] The mixture is poured into a mold and repeatedly shaken.

[0064] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0065] In the mixture, the volume fraction of graphite is 20-75 vol%, for example, 20 vol%, 25 vol%, 32 vol%, 48 vol%, 50 vol%, 55 vol%, 60 vol%, 65 vol%, 70 vol%, 75 vol%, with the remainder being aluminum matrix powder.

[0066] In the preparation of the aluminum-based composite material of the present invention, the mixture is placed into a mold and repeatedly vibrated to ensure the consistency of graphite orientation. At the same time, a vacuum hot pressing powder metallurgy process is adopted to achieve graphite orientation along the direction parallel to the heat flow, realizing the directional arrangement of graphite, which has high orientation and achieves efficient heat conduction in the specified direction.

[0067] The preparation of aluminum-based composite materials in this invention involves few steps and simple operation, making it easy for industrial production. This invention does not introduce any chemical reagents or toxic or polluting gases, thus having the advantage of being environmentally friendly.

[0068] In the heat sink of the present invention, a groove is formed on one side of the base plate, and one end of the heat dissipation fin is embedded in the groove and welded to the base plate.

[0069] In this invention, the shape of the heat dissipation fins is not particularly limited, and the longitudinal cross-section of the heat dissipation fins can be rectangular, trapezoidal, or triangular. Preferably, the longitudinal cross-section of the heat dissipation fins can be rectangular.

[0070] In this invention, there are multiple heat dissipation fins with gaps between them. This ensures that the surface area of ​​the base plate is not wasted and that the heat dissipation fins are in contact with cooler air, thus guaranteeing that the heat dissipation fins have good heat dissipation capabilities.

[0071] To better understand the above technical solutions, the following detailed description will be provided in conjunction with specific embodiments. These embodiments are merely preferred implementations of the present invention and are not intended to limit the scope of the invention.

[0072] Example 1

[0073] A composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. A groove is formed on one side of the base plate, and one end of the heat dissipation fins is embedded in the groove and welded to the base plate.

[0074] The base plate and heat dissipation fins are both made of aluminum-based composite material.

[0075] The preparation method of the aluminum-based composite material includes the following steps:

[0076] Provide aluminum matrix powder; wherein the aluminum matrix is ​​aluminum alloy 3003;

[0077] The aluminum matrix powder and graphite are mixed evenly to obtain a mixture; wherein, in the mixture, the volume fraction of graphite is 20 vol%, and the remainder is aluminum matrix powder;

[0078] The mixture is poured into a mold and repeatedly shaken.

[0079] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0080] The aluminum matrix powder has an average particle size of 5 μm and is prepared by gas atomization.

[0081] The thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm.

[0082] The graphite is flake graphite; the flake graphite has a diameter of 200 μm and a thickness of 20 μm.

[0083] The planar direction of the flake graphite in the base plate is parallel to the direction of the heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of the heat flow through the heat dissipation fins.

[0084] Example 2

[0085] A composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. A groove is formed on one side of the base plate, and one end of the heat dissipation fins is embedded in the groove and welded to the base plate.

[0086] The base plate and heat dissipation fins are both made of aluminum-based composite material.

[0087] The preparation method of the aluminum-based composite material includes the following steps:

[0088] Provide aluminum matrix powder; wherein the aluminum matrix is ​​aluminum alloy 3003;

[0089] The aluminum matrix powder and graphite are mixed evenly to obtain a mixture; wherein, in the mixture, the volume fraction of graphite is 20 vol%, and the remainder is aluminum matrix powder;

[0090] The mixture is poured into a mold and repeatedly shaken.

[0091] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0092] The aluminum matrix powder has an average particle size of 5 μm and is prepared by gas atomization.

[0093] The graphite surface is covered with a coating made of silicon; the coating thickness is 150 μm.

[0094] The thickness of the oxide film on the surface of the aluminum substrate powder is greater than 4 nm.

[0095] The graphite is flake graphite; the flake graphite has a diameter of 200 μm and a thickness of 20 μm.

[0096] The planar direction of the flake graphite in the base plate is parallel to the direction of the heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of the heat flow through the heat dissipation fins.

[0097] Example 3

[0098] A composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. A groove is formed on one side of the base plate, and one end of the heat dissipation fins is embedded in the groove and welded to the base plate.

[0099] The base plate and heat dissipation fins are both made of aluminum-based composite material.

[0100] The preparation method of the aluminum-based composite material includes the following steps:

[0101] Provide aluminum matrix powder; wherein the aluminum matrix is ​​aluminum alloy 3003;

[0102] The aluminum matrix powder and graphite are mixed evenly to obtain a mixture; wherein, in the mixture, the volume fraction of graphite is 20 vol%, and the remainder is aluminum matrix powder;

[0103] The mixture is poured into a mold and repeatedly shaken.

[0104] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0105] The aluminum matrix powder has an average particle size of 5 μm and is prepared by gas atomization.

[0106] The graphite surface is covered with a coating made of silicon; the coating thickness is 150 μm.

[0107] The thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm.

[0108] The graphite is flake graphite; the flake graphite has a diameter of 200 μm and a thickness of 20 μm.

[0109] Example 4

[0110] A composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. A groove is formed on one side of the base plate, and one end of the heat dissipation fins is embedded in the groove and welded to the base plate.

[0111] The base plate and heat dissipation fins are both made of aluminum-based composite material.

[0112] The preparation method of the aluminum-based composite material includes the following steps:

[0113] Provide aluminum matrix powder; wherein the aluminum matrix is ​​aluminum alloy 3003;

[0114] The aluminum matrix powder and graphite are mixed evenly to obtain a mixture; wherein, in the mixture, the volume fraction of graphite is 32 vol%, and the remainder is aluminum matrix powder;

[0115] The mixture is poured into a mold and repeatedly shaken.

[0116] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0117] The aluminum matrix powder has an average particle size of 20 μm and is prepared by gas atomization.

[0118] The thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm.

[0119] The graphite surface is covered with a coating made of silicon; the coating thickness is 150 μm.

[0120] The graphite is flake graphite; the flake graphite has a diameter of 500 μm and a thickness of 10 μm.

[0121] The planar direction of the flake graphite in the base plate is parallel to the direction of the heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of the heat flow through the heat dissipation fins.

[0122] Example 5

[0123] A composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. A groove is formed on one side of the base plate, and one end of the heat dissipation fins is embedded in the groove and welded to the base plate.

[0124] The base plate and heat dissipation fins are both made of aluminum-based composite material.

[0125] The preparation method of the aluminum-based composite material includes the following steps:

[0126] Provide aluminum matrix powder; wherein the aluminum matrix is ​​aluminum alloy 3003;

[0127] The aluminum matrix powder and graphite are mixed evenly to obtain a mixture; wherein, in the mixture, the volume fraction of graphite is 48 vol%, and the remainder is aluminum matrix powder;

[0128] The mixture is poured into a mold and repeatedly shaken.

[0129] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0130] The aluminum matrix powder has an average particle size of 100 μm and is prepared by gas atomization.

[0131] The thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm.

[0132] The graphite surface is covered with a coating made of silicon carbide; the coating thickness is 100 μm.

[0133] The graphite is flake graphite; the diameter of the flake graphite is 1000 μm and the thickness is 50 μm.

[0134] The planar direction of the flake graphite in the base plate is parallel to the direction of the heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of the heat flow through the heat dissipation fins.

[0135] Example 6

[0136] A composite heat sink includes a base plate and heat dissipation fins disposed on the base plate. A groove is formed on one side of the base plate, and one end of the heat dissipation fins is embedded in the groove and welded to the base plate.

[0137] The base plate and heat dissipation fins are both made of aluminum-based composite material.

[0138] The preparation method of the aluminum-based composite material includes the following steps:

[0139] Provide aluminum matrix powder; wherein the aluminum matrix is ​​aluminum alloy 3003;

[0140] The aluminum matrix powder and graphite are mixed evenly to obtain a mixture; wherein, in the mixture, the volume fraction of graphite is 75 vol%, and the remainder is aluminum matrix powder;

[0141] The mixture is poured into a mold and repeatedly shaken.

[0142] The mold containing the mixture, after being shaken, is placed in a vacuum hot press furnace, and a vacuum is first drawn to 10. -3 Below Pa, gradually heat until the temperature rises to 800℃, then slowly apply pressure to the mold until a pressure of 40MPa is reached, hold the pressure for 10-30 minutes, cool, and demold.

[0143] The aluminum matrix powder has an average particle size of 1 μm and is prepared by gas atomization.

[0144] The thickness of the oxide film on the surface of the aluminum substrate powder is less than 4 nm.

[0145] The graphite surface is covered with a coating, the coating material being silicon or a metal material; the coating thickness is 200 μm.

[0146] The graphite is flake graphite; the flake graphite has a diameter of 150 μm and a thickness of 30 μm.

[0147] The planar direction of the flake graphite in the base plate is parallel to the direction of the heat flow through the base plate; the planar direction of the flake graphite in the heat dissipation fins is parallel to the direction of the heat flow through the heat dissipation fins.

[0148] Comparative Example 1

[0149] Based on Embodiment 1, the only difference is that the base plate and heat dissipation fins are both made of aluminum alloy 3003.

[0150] Test case

[0151] To verify the performance of the product of the present invention, the thermal conductivity of the heat sinks prepared in Examples 1-6 and Comparative Example 1 were tested respectively, and the specific results are as follows:

[0152]

[0153]

[0154] The above tests show that by controlling the thickness of the oxide film on the surface of the aluminum substrate powder to be less than 4nm and by covering the graphite surface with a coating, the thermal conductivity of the heat sink can be improved, thus enhancing its heat dissipation effect.

[0155] The above tests show that the planar orientation of the flake graphite in the base plate is parallel to the direction of heat flow through the base plate; the planar orientation of the flake graphite in the heat dissipation fins is parallel to the direction of heat flow through the heat dissipation fins. This invention, by controlling the orientation of the flake graphite in the base plate and heat dissipation fins, ensures that the orientation direction of the flake graphite is consistent with the direction of heat flow, thus fully utilizing the high thermal conductivity of the planar aspect of the flake graphite to achieve a good heat dissipation effect.

[0156] The above embodiments merely illustrate the implementation of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention. Any technical solutions obtained by adopting equivalent substitutions or equivalent transformations should fall within the protection scope of the present invention.

Claims

1. A composite heat sink comprising a base plate and heat dissipation fins disposed on the base plate, characterized in that, The bottom plate and the heat dissipation fin are both made of an aluminum matrix composite material, the aluminum matrix composite material comprises an aluminum matrix and graphite; the raw material of the aluminum matrix is aluminum matrix powder; the thickness of the surface oxide film of the aluminum matrix powder is less than 4nm; the surface of the graphite is covered with a plating layer, the material of the plating layer is silicon material; the volume fraction of the graphite is 32-48vol%, the rest is aluminum matrix powder; the average particle size of the aluminum matrix powder is 20-100μm; the graphite is flaky graphite; the flaky plane direction of the flaky graphite in the bottom plate is parallel to the direction of the heat flow flowing through the bottom plate; the flaky plane direction of the flaky graphite in the heat dissipation fin is parallel to the direction of the heat flow flowing through the heat dissipation fin; the thickness of the plating layer is 100-150μm, the diameter of the flaky graphite is 500-1000μm, and the thickness is 10-50μm; the aluminum matrix powder is prepared by a gas atomization method.

2. The composite heat spreader of claim 1, wherein The aluminum matrix is aluminum or aluminum alloy.

3. The composite heat spreader of claim 1, wherein The preparation method of the aluminum matrix composite material comprises the following steps: providing aluminum matrix powder; mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; putting the mixture into a mold for repeated oscillation; The oscillated mould containing the mixture is placed in a vacuum hot press furnace, first vacuumed to 10 -3 Pa, then gradually heated to 800°C, and the mould is slowly pressed until the pressure reaches 40 MPa, kept for 10-30 min, cooled, and demoulded.

4. The composite heat spreader of claim 1, wherein, The in-plane thermal conductivity of the heat sink reaches 300 W / m·K, and the density is lower than 2.5 g / cm 3 .

5. The composite heat spreader of claim 1, wherein the bottom plate is provided with a groove on one side, and one end of the heat dissipation fin is embedded in the groove and welded to the bottom plate.

6. The use of the composite heat sink according to any one of claims 1-5 in high-power heat generating electronic equipment.

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