CN114531820A - Composite radiator and application thereof - Google Patents

Abstract

The invention discloses a composite radiator and application thereof, wherein the composite radiator comprises a bottom plate and radiating fins arranged on the bottom plate, the bottom plate and the radiating fins are both made of aluminum matrix composite material, and the aluminum matrix composite material comprises aluminum matrix and graphite. The composite radiator provided by the invention is made of an aluminum-based composite material, the aluminum-based composite material is formed by compounding an aluminum matrix and graphite, the in-plane heat conductivity coefficient of the obtained radiator can reach 300W/m.K, and the density is lower than 2.5g/cm³The heat dissipation structure has the advantages of good heat dissipation effect, light weight, small thermal resistance and low production cost.

Description

A composite radiator and its application

technical field

The invention relates to the field of radiator components, in particular to a composite radiator and its application.

Background technique

With the vigorous development of high technology, the volume of electronic components tends to be miniaturized, and the density per unit area is getting higher and higher, and its performance cannot be enhanced. Under these factors, the total calorific value of electronic components increases almost year by year. high. In order to ensure the normal operation of electronic components, it is necessary to install a radiator to dissipate heat to prevent some electronic components from working at high temperatures and shortening their service life.

In the prior art, the heat sink is generally divided into two parts, namely the base plate of the heat sink and the heat dissipation fins. The base plate of the heat sink is the place where the heat is in contact with the electronic components and the heat is collected, and the heat dissipation fin is the end point of heat conduction. Eventually the heat is dissipated into the air. The heat dissipation principle of the radiator of this structure mainly relies on the way of heat conduction, so it needs a larger surface area and a higher thermal conductivity. The performance of the radiator is not only related to the structure of the radiator, but also depends on the material selection of the radiator. The radiator material refers to the specific material used in the body of the radiator.

There are three main types of radiator materials commonly used at present: (1) Pure aluminum radiator: The bottom plate and fins of the radiator are made of pure aluminum or 6063 alloy, both of which have good thermal conductivity, but industrial The thermal conductivity can reach about 200W/m·K; (2) Pure copper radiator: the bottom plate and cooling fins of the radiator are made of pure copper, and the copper heat transfer coefficient can reach 400W/m·K, which can be significantly improved Heat exchange efficiency; (3) Copper-aluminum composite radiator: the bottom plate of the radiator is made of pure copper, and the heat dissipation fins are made of aluminum alloy.

However, in the process of implementing the embodiments of the present application, the inventor of the present application found that the above-mentioned technology has at least the following technical problems: on the electronic components with continuously increasing calorific value, the pure aluminum radiator cannot meet the heat dissipation requirements, and the volume of the heat dissipation function can be realized. Large; pure copper radiator is heavy and expensive, which is not conducive to popularization and application; poor connection between the copper bottom plate and the aluminum fins of the copper-aluminum composite heat exchanger will cause a large contact thermal resistance and affect the heat dissipation effect.

Therefore, it has become an urgent technical problem to be solved in the art to provide a heat sink with good heat dissipation effect, light weight, low thermal resistance and low production cost.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to propose a composite radiator and its application, which solves the technical problem that the radiator in the prior art is difficult to take into account good heat dissipation effect, light weight, low thermal resistance and low production cost at the same time.

The technical problem to be solved by the present invention is realized through the following technical solutions:

In one aspect of the present invention, the present invention provides a composite heat sink, comprising a base plate and heat dissipation fins disposed on the base plate, wherein the base plate and the heat dissipation fins are both made of aluminum-based composite materials, The aluminum-based composite material includes an aluminum matrix and graphite.

Optionally, the aluminum matrix is aluminum or an aluminum alloy; the raw material of the aluminum matrix is aluminum matrix powder.

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

Optionally, the aluminum matrix powder is prepared by a gas atomization method.

Optionally, the thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm.

Optionally, the graphite surface is covered with a plating layer, and the material of the plating layer is silicon material or metal material; the thickness of the plating layer is 100-200 μm.

Optionally, the graphite is flake graphite.

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

Optionally, the flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fin is parallel to the direction of the flake graphite flowing through the heat dissipation fin. The heat flow directions of the sheets are parallel.

Optionally, the preparation method of the aluminum matrix composite material includes the following steps:

Provide aluminum matrix powder;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Optionally, in the mixture, the volume fraction of the graphite is 20-75 vol%, and the rest is aluminum matrix powder.

Optionally, a groove is formed on one side of the bottom plate, and one end of the heat dissipation fin is embedded in the groove and connected to the bottom plate by welding.

In yet another aspect of the present invention, the present invention provides the application of the above-mentioned composite heat sink in a high-power heat-generating electronic device.

The present invention has the following beneficial effects:

The composite radiator provided by the invention is made of an aluminum-based composite material, and the aluminum-based composite material is composed of an aluminum matrix and graphite. 2.5g/cm ³ , which can take into account good heat dissipation effect, light weight, low thermal resistance and low production cost at the same time.

The density difference between the graphite and the aluminum matrix is very large, and the interface between the graphite and the aluminum matrix has poor wettability, so that the graphite cannot be well dispersed in the aluminum matrix, and the compatibility between the graphite and the aluminum matrix is poor; The formation of intermetallic compounds at the interface produces a large thermal resistance at the interface, so that the high thermal conductivity of graphite cannot be fully exerted, and the thermal conductivity effect is affected. In order to solve the above problems, in the present invention, by controlling the thickness of the oxide film on the surface of the aluminum matrix powder to be less than 4 nm, and covering the graphite surface with a coating layer, the wettability between the graphite and the aluminum matrix can be improved, and the graphite and the aluminum matrix can be enhanced. The compatibility between the aluminum matrix prevents the adverse interface reaction between carbon and aluminum, reduces the interface thermal resistance, and further improves the thermal conductivity of the aluminum matrix composite material.

The artificially synthesized flake graphite has a thermal conductivity of 1200-1800W/m·K along the flake plane, and has been successfully mass-produced. However, the thermal conductivity of flake graphite in the direction perpendicular to the flake plane is extremely low, only 10-20W/m·K, which greatly affects the heat dissipation effect. In order to solve the above problems, in the present invention, the sheet-like plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; The direction of heat flow through the heat dissipation fins is parallel. The invention controls the orientation of the flake graphite in the bottom plate and the heat dissipation fins, so that the orientation direction of the flake graphite is consistent with the heat flow direction, and can make full use of the high thermal conductivity of the flake graphite in the plane direction to form a good heat dissipation effect.

The composite radiator of the invention can be applied to various electronic components, can improve the heat dissipation efficiency of the electronic components, improve the reliability of the electronic components, and is beneficial to prolong the service life of the electronic components.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

1 is a schematic structural diagram of a composite heat sink according to Embodiment 1 of the present invention;

FIG. 2 is a schematic structural diagram of a composite heat sink according to Embodiment 3 of the present invention.

Description of reference numbers:

label name label name 1 Flake graphite 2 Aluminum base 3 bottom plate 4 cooling fins

Detailed ways

The raw materials and equipment used in the present invention, unless otherwise specified, are the common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are the conventional methods in the art.

Unless otherwise specified, the meanings of the terms in this specification are the same as those generally understood by those skilled in the art, but in case of conflict, the definitions in this specification shall prevail.

"Comprising," "comprising," "including," "containing," "having," or other variations herein are intended to encompass non-closed includes, and no distinction is made between these terms. The term "comprising" means that other steps and ingredients may be added that do not affect the final result. The term "comprising" also includes the terms "consisting of" and "consisting essentially of." The compositions and methods/processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein and any additional or optional ingredients, components, steps or limitations described herein.

All numerical values or expressions used in the specification and claims referring to component amounts, process conditions, etc., should be understood to be modified by "about" in all instances. All ranges referring to the same component or property are inclusive of the endpoints, which endpoints are independently combinable. Since these ranges are continuous, they include every value between the minimum and maximum values. It is also to be understood that any numerical range recited herein is intended to include all subranges within that range.

As described in the background art, there are technical problems in the prior art that the heat sink is difficult to take into account good heat dissipation effect, light weight, low thermal resistance and low production cost at the same time. In order to solve the above technical problems, the present invention provides a composite heat sink and its application.

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

In the present invention, the aluminum substrate is aluminum or aluminum alloy. For the aluminum alloy, the specific composition of the aluminum alloy is not particularly limited in the present invention. Preferably, the aluminum alloy is 3003 or 6063.

The aluminum matrix in the aluminum matrix composite material acts as a thermal conductive matrix on the one hand, and plays the role of bonding and fixing graphite on the other hand. As a traditional thermal conductive material, aluminum matrix has good thermal conductivity and high strength. Combining it with graphite with high thermal conductivity can further improve the thermal conductivity of aluminum matrix composites.

The composite radiator of the present invention does not require forced convection by a fan, but can dissipate heat through natural convection, so it has the characteristics of no noise and no dust.

The in-plane thermal conductivity of the composite radiator of the invention can reach 300W/m·K, can be applied to various electronic components, can improve the heat dissipation efficiency of the electronic components, improve the reliability of the electronic components, and is conducive to extending the electronic components. service life.

In the present invention, the raw material of the aluminum matrix is aluminum matrix powder.

In the present invention, the average particle size of the aluminum matrix powder is 1-100 μm, such as 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 the range between them. any value.

In the present invention, the aluminum matrix powder is prepared by a gas atomization method.

The present invention has no particular limitations on the specific process and conditions for preparing the aluminum matrix powder by the gas atomization method. Select and adjust according to the situation, product requirements and quality requirements. Preferably, the preparation method of the aluminum matrix powder is as follows: using high-pressure gas as an atomization medium to break the molten aluminum matrix fine flow to obtain the aluminum matrix powder, the aluminum matrix powder is smooth and spherical, and the cooling rate is 100 ℃/s , wherein the high-pressure gas includes nitrogen and oxygen with a purity of more than 99.9%, wherein the volume content of the oxygen is 0.05-1.5%.

In the present invention, the thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm. In this way, it can avoid the generation of tiny pores that affect the sintering effect and reduce the heat transfer performance and strength.

In the present invention, the surface of the graphite is covered with a plating layer. In this way, the surface energy between the two phases can be reduced, the porosity can be reduced, and the Al-C compound generated during the heating and smelting process can be avoided to generate thermal resistance and reduce thermal conductivity.

In the present invention, the material of the plating layer is not particularly limited, as long as the above functions can be achieved. Preferably, the material of the plating layer is silicon material or metal material, more preferably, the material of the plating layer is silicon.

In the present invention, the thickness of the plating layer is 100-200 μm, such as 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm and any value therebetween.

In the present invention, the preparation method of the graphite surface covered with the coating is not particularly limited, and the conventional preparation process of the coating well known to those skilled in the art can be used, and those skilled in the art can select according to the actual production situation, product requirements and quality requirements and adjustment. Taking the graphite surface covered with a silicon layer as an example, the preparation method is as follows: the cleaned and dried graphite is evenly mixed with anhydrous calcium chloride powder and silicon powder, and then placed in a crucible, and then heated in a vacuum carbon tube furnace. The set heating program is heated to 1200°C, and kept for 2 hours. After the heating and heating program of the carbon tube furnace is completed, the furnace body is naturally cooled to room temperature, and then the blended powder is taken out; the blended powder is washed with hot water. , dissolve calcium chloride; wherein, the mass ratio of graphite and anhydrous calcium chloride powder is 1:1, the mass ratio of graphite and silicon powder is 6-8:1, and the diameter of the silicon powder is 20 μm within.

In practice, the inventor found that the density difference between graphite and aluminum matrix is very large, and the interface between graphite and aluminum matrix has poor wettability, resulting in graphite not being well dispersed in aluminum matrix, and poor compatibility between graphite and aluminum matrix; in addition, graphite and aluminum matrix have poor compatibility. The interface reaction of the matrix is difficult to control, and it is easy to form interfacial intermetallic compounds, resulting in a large thermal resistance at the interface, so that the high thermal conductivity of graphite cannot be fully exerted, and the thermal conductivity effect is affected. In order to solve the above problems, in the present invention, by controlling the thickness of the oxide film on the surface of the aluminum matrix powder to be less than 4 nm, and covering the graphite surface with a coating layer, the wettability between the graphite and the aluminum matrix can be improved, and the graphite and the aluminum matrix can be enhanced. The compatibility between the aluminum matrix prevents the adverse interface reaction between carbon and aluminum, reduces the interface thermal resistance, and further improves the thermal conductivity of the aluminum matrix composite material.

The morphology of graphite can be divided into four categories, namely flake graphite, spherical graphite, vermicular graphite and flocculent graphite. In the present invention, the graphite is preferably flake graphite. Wherein, the diameter of the flake graphite is 150-1000 μm, and the thickness is 10-50 μm.

In the present invention, the flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fins is parallel to the direction of the flake graphite flowing through the heat dissipation fins The heat flow directions of the sheets are parallel.

It should be noted that, in the present invention, the electronic components are in contact with the bottom plate, and the electronic components are arranged in the center of the bottom plate. On-chip heat dissipation.

Graphite, as a material with abundant domestic resources and low cost, is an allotrope of carbon and belongs to the hexagonal crystal system. Each carbon atom in the lamella is connected with three other carbon atoms by covalent bonds. The honeycomb-like arrangement of multiple hexagons is connected by van der Waals force between the sheets, which makes it exhibit a lot of anisotropy of properties. At the same time, graphite also has light weight (density ~ 2.26g·cm-3), good high temperature resistance, thermal shock resistance, and corrosion resistance. The artificially synthesized flake graphite has a thermal conductivity of 1200-1800W/m·K along the flake plane, and has been successfully mass-produced. However, the thermal conductivity of flake graphite in the direction perpendicular to the flake plane is extremely low, only 10-20W/m·K, which greatly affects the heat dissipation effect. In order to solve the above problems, in the present invention, the sheet-like plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; The direction of heat flow through the heat dissipation fins is parallel. The invention controls the orientation of the flake graphite in the bottom plate and the heat dissipation fins, so that the orientation direction of the flake graphite is consistent with the heat flow direction, and can make full use of the high thermal conductivity of the flake graphite in the plane direction to form a good heat dissipation effect.

In the present invention, the preparation method of the aluminum-based composite material includes the following steps:

Provide aluminum matrix powder;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, in the mixture, the volume fraction of the graphite is 20-75vol%, such as 20vol%, 25vol%, 32vol%, 48vol%, 50vol%, 55vol%, 60vol%, 65vol%, 70vol%, 75vol% , and the rest are aluminum matrix powder.

In the preparation of the aluminum-based composite material of the present invention, the mixture is loaded into a mold for repeated oscillations to ensure the consistency of graphite orientation, and a vacuum hot pressing powder metallurgy process is adopted at the same time, and the graphite is oriented parallel to the direction of heat flow. , realizes the directional arrangement of graphite, has high orientation, and realizes the efficient conduction of heat in the specified direction.

In the preparation of the aluminum-based composite material in the present invention, the whole process has few steps, simple operation, and is convenient for industrial production; the present invention does not introduce any chemical reagents and toxic and polluting gases, and has the advantage of being environmentally friendly.

In the heat sink of the present invention, a groove is formed on one side of the bottom plate, and one end of the heat dissipation fin is embedded in the groove and connected to the bottom plate by welding.

In the present invention, the shape of the heat dissipation fin is not particularly limited, and the longitudinal section of the heat dissipation fin may be a rectangle, a trapezoid, or a triangle. Preferably, the longitudinal section of the heat dissipation fins may be rectangular.

In the present invention, the number of the heat dissipation fins is multiple, and there are gaps between the heat dissipation fins. In this way, the surface area of the bottom plate is not wasted, and the heat dissipation fins and the lower temperature air can be ensured. contact to ensure that the heat dissipation fins have better heat dissipation capacity.

In order to better understand the above technical solutions, the above technical solutions will be described in detail below with reference to specific examples, which are only preferred embodiments of the present invention, and are not intended to limit the present invention.

Example 1

A composite heat sink comprises a base plate and a heat dissipation fin arranged on the base plate, 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 connected to the base plate by welding .

The bottom plate and the heat dissipation fins are all made of aluminum-based composite materials.

The preparation method of the aluminum matrix composite material comprises the following steps:

Provide aluminum matrix powder; wherein, the aluminum matrix is aluminum alloy 3003;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; wherein, in the mixture, the volume fraction of the graphite is 20 vol%, and the rest is the aluminum matrix powder;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, the average particle size of the aluminum matrix powder is 5 μm; the aluminum matrix powder is prepared by a gas atomization method.

The thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm.

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

The flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fins is parallel to the heat flow direction flowing through the heat dissipation fins parallel.

Example 2

A composite heat sink comprises a base plate and a heat dissipation fin arranged on the base plate, 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 connected to the base plate by welding .

The bottom plate and the heat dissipation fins are all made of aluminum-based composite materials.

The preparation method of the aluminum matrix composite material comprises the following steps:

Provide aluminum matrix powder; wherein, the aluminum matrix is aluminum alloy 3003;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; wherein, in the mixture, the volume fraction of the graphite is 20 vol%, and the rest is the aluminum matrix powder;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, the average particle size of the aluminum matrix powder is 5 μm; the aluminum matrix powder is prepared by a gas atomization method.

The surface of the graphite is covered with a plating layer, and the material of the plating layer is silicon; the thickness of the plating layer is 150 μm.

The thickness of the oxide film on the surface of the aluminum base powder is greater than 4 nm.

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

The flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fins is parallel to the heat flow direction flowing through the heat dissipation fins parallel.

Example 3

A composite heat sink comprises a base plate and a heat dissipation fin arranged on the base plate, 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 connected to the base plate by welding .

The bottom plate and the heat dissipation fins are all made of aluminum-based composite materials.

The preparation method of the aluminum matrix composite material comprises the following steps:

Provide aluminum matrix powder; wherein, the aluminum matrix is aluminum alloy 3003;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; wherein, in the mixture, the volume fraction of the graphite is 20 vol%, and the rest is the aluminum matrix powder;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, the average particle size of the aluminum matrix powder is 5 μm; the aluminum matrix powder is prepared by a gas atomization method.

The surface of the graphite is covered with a plating layer, and the material of the plating layer is silicon; the thickness of the plating layer is 150 μm.

The thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm.

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

Example 4

A composite heat sink comprises a base plate and a heat dissipation fin arranged on the base plate, 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 connected to the base plate by welding .

The bottom plate and the heat dissipation fins are all made of aluminum-based composite materials.

The preparation method of the aluminum matrix composite material comprises the following steps:

Provide aluminum matrix powder; wherein, the aluminum matrix is aluminum alloy 3003;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; wherein, in the mixture, the volume fraction of the graphite is 32 vol%, and the rest is the aluminum matrix powder;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, the average particle size of the aluminum matrix powder is 20 μm; the aluminum matrix powder is prepared by a gas atomization method.

The thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm.

The graphite surface is covered with a plating layer, and the material of the plating layer is silicon; the thickness of the plating layer is 150 μm.

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

The flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fins is parallel to the heat flow direction flowing through the heat dissipation fins parallel.

Example 5

A composite radiator, comprising a base plate and a heat dissipation fin arranged on the base plate, 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 connected to the base plate by welding .

The bottom plate and the heat dissipation fins are all made of aluminum-based composite materials.

The preparation method of the aluminum matrix composite material comprises the following steps:

Provide aluminum matrix powder; wherein, the aluminum matrix is aluminum alloy 3003;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; wherein, in the mixture, the volume fraction of the graphite is 48 vol%, and the rest is the aluminum matrix powder;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, the average particle size of the aluminum matrix powder is 100 μm; the aluminum matrix powder is prepared by a gas atomization method.

The thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm.

The surface of the graphite is covered with a plating layer, and the material of the plating layer is silicon carbide; the thickness of the plating layer is 100 μm.

The graphite is flake graphite; the flake graphite has a diameter of 1000 μm and a thickness of 50 μm.

The flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fins is parallel to the heat flow direction flowing through the heat dissipation fins parallel.

Example 6

A composite radiator, comprising a base plate and a heat dissipation fin arranged on the base plate, 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 connected to the base plate by welding .

The bottom plate and the heat dissipation fins are all made of aluminum-based composite materials.

The preparation method of the aluminum matrix composite material comprises the following steps:

Provide aluminum matrix powder; wherein, the aluminum matrix is aluminum alloy 3003;

Mixing the aluminum matrix powder and graphite uniformly to obtain a mixture; wherein, in the mixture, the volume fraction of the graphite is 75 vol%, and the rest is the aluminum matrix powder;

The mixture is loaded into a mold for repeated shaking;

Put the shaken mold containing the mixture into a vacuum hot-pressing furnace, first vacuumize to below 10 ^-3 Pa, then gradually heat until the temperature rises to 800°C, and slowly apply pressure to the mold until Reach the pressure of 40MPa, keep the pressure for 10-30min, cool and demould.

Wherein, the average particle size of the aluminum matrix powder is 1 μm; the aluminum matrix powder is prepared by a gas atomization method.

The thickness of the oxide film on the surface of the aluminum base powder is less than 4 nm.

The graphite surface is covered with a plating layer, and the material of the plating layer is silicon material or metal material; the thickness of the plating layer is 200 μm.

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

The flake plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; the flake plane direction of the flake graphite in the heat dissipation fins is parallel to the heat flow direction flowing through the heat dissipation fins parallel.

Comparative Example 1

Based on Embodiment 1, the only difference is that the bottom plate and the heat dissipation fins are all made of aluminum alloy 3003.

test case

In order to verify the performance of the product of the present invention, the thermal conductivity of the radiators prepared in Examples 1-6 and Comparative Example 1 were tested respectively, and the specific results are as follows:

It can be seen from the above test that by controlling the thickness of the oxide film on the surface of the aluminum base powder to be less than 4 nm, and covering the graphite surface with a coating layer, the thermal conductivity of the radiator can be improved and the heat dissipation effect of the radiator can be improved.

It can be seen from the above test that the sheet-like plane direction of the flake graphite in the bottom plate is parallel to the direction of heat flow through the bottom plate; The heat flow directions of the fins are parallel. The invention controls the orientation of the flake graphite in the bottom plate and the heat dissipation fins, so that the orientation direction of the flake graphite is consistent with the heat flow direction, and can make full use of the high thermal conductivity of the flake graphite in the plane direction to form a good heat dissipation effect.

The above-mentioned embodiment only expresses the embodiment of the present invention, and its description is more specific and detailed, but it should not be construed as a limitation on the scope of the present invention, but all technical solutions obtained in the form of equivalent replacement or equivalent transformation , should fall within the protection scope of the present invention.

Claims (13)

1. The composite radiator comprises a bottom plate and radiating fins arranged on the bottom plate, and is characterized in that the bottom plate and the radiating fins are both made of aluminum matrix composite materials, and the aluminum matrix composite materials comprise aluminum matrix and graphite.

2. The composite heat sink of claim 1, wherein the aluminum matrix is aluminum or an aluminum alloy; the raw material of the aluminum matrix is aluminum matrix powder.

3. The composite heat spreader of claim 2, wherein the aluminum matrix powder has an average particle size of 1-100 μ ι η; the aluminum matrix powder is prepared by adopting a gas atomization method.

4. The composite heat spreader of claim 2, wherein the aluminum matrix powder surface oxide film has a thickness of less than 4 nm.

5. The composite heat sink as claimed in claim 1, wherein the graphite surface is covered with a plating layer, and the plating layer is made of silicon material or metal material; the thickness of the plating layer is 100-200 mu m.

6. The composite heat spreader of claim 1, wherein the graphite is flake graphite.

7. The composite heat sink as claimed in claim 6, wherein the flake graphite has a diameter of 150-1000 μm and a thickness of 10-50 μm.

8. The composite heat sink of claim 6, wherein the planar orientation of the platelets of graphite in the base plate is parallel to the direction of heat flow through the base plate; the direction of the flake plane of the flake graphite in the radiating fins is parallel to the direction of heat flow passing through the radiating fins.

9. The composite heat sink of claim 1, wherein the aluminum matrix composite is prepared by a method comprising the steps of:

providing an aluminum matrix powder;

uniformly mixing the aluminum matrix powder and graphite to obtain a mixture;

loading the mixture into a mold for repeated oscillation;

placing the vibrated mould filled with the mixture into a vacuum hot-pressing furnace, and firstly vacuumizing to 10 DEG^-3And Pa below, gradually heating until the temperature rises to 800 ℃, starting to slowly apply pressure to the mould until the pressure reaches 40MPa, keeping the pressure for 10-30min, cooling, and demoulding.

10. The composite heat sink of claim 9, wherein the volume fraction of graphite in the mixture is 20-75 vol%, the balance being aluminum matrix powder.

11. The composite heat sink of claim 1, wherein the heat sink has an in-plane thermal conductivity of up to 300W/m-K and a density of less than 2.5g/cm³。

12. The composite heat sink as claimed in claim 1, wherein a groove is formed at one side of the base plate, and one end of the heat dissipating fins is embedded in the groove and is welded to the base plate.

13. Use of a composite heat sink according to any of claims 1-12 in high power heat generating electronic devices.

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