CN112122616A

CN112122616A - Directional microchannel and disordered hole composite heat sink and preparation method thereof

Info

Publication number: CN112122616A
Application number: CN202010853795.6A
Authority: CN
Inventors: 刁开侃
Original assignee: Wuhan Hanwei New Material Technology Co ltd
Current assignee: Wuhan Hanwei New Material Technology Co ltd
Priority date: 2020-08-24
Filing date: 2020-08-24
Publication date: 2020-12-25

Abstract

The invention discloses a directional microchannel and disordered hole composite heat sink, which comprises a heat sink body, wherein a plurality of microchannels penetrating through the whole heat sink body are arranged on the heat sink body in the same direction, and a plurality of micropores are also arranged among the microchannels of the heat sink body. The invention also discloses a preparation method of the heat sink, which comprises the steps of pulping, wire burying, drying, pre-sintering, sintering reduction and the like. The invention has simple integral preparation process and lower manufacturing cost, and the prepared heat sink has continuous micro-channels and micro-holes for assisting heat exchange and extremely excellent heat dispersion.

Description

Directional microchannel and disordered hole composite heat sink and preparation method thereof

Technical Field

The invention relates to the technical field of heat sink heat dissipation, in particular to a composite heat sink with a directional microchannel and a disordered hole and a preparation method thereof.

Background

With the development of the microelectronics industry and the new energy industry, heat dissipation is an important subject to be faced, especially in relatively closed environments, such as heat dissipation of electric vehicle battery packs, electronic components of large-scale wind power generation equipment and supercomputer integrated chips. According to the united states space administration (NASA), 90% of the task failures are due to failures that occur as electronic components overheat. In the "key project of the 2020 annual project of the" key scientific problem of the revolutionary technology "issued by the science and technology department, the new principle and the key technology of the heat dissipation of the microchannel with the ultrahigh heat flow density are listed as the third major scientific and technological problem which needs to be solved urgently. It is clearly indicated that the efficient heat dissipation system for the ultra-high heat flow density chip is developed by developing a flow-solid-heat-force-electricity multi-element cooperative technology. Therefore, the novel heat exchange micro-channel structure is prepared by a new technical means, the fluidity of the fluid in the micro-channel is improved, the contact heat transfer area of the fluid and the micro-channel is enlarged, and the absorption rate of the cooling liquid to the heat transferred by a heat source is increased, so that the heat exchange efficiency of the cooling liquid in the micro-channel is improved, and the method is one of important feasible methods for solving the scientific problem.

Most of the forced convection heat dissipation materials developed by the present technology are mainly single-layer microchannel heat sinks and disordered

porous metals

1, 2. In response to high heat flux density heating elements, copper is commonly used in these heat sink materials because of its high heat transfer and heat dissipation efficiency (copper thermal conductivity of 403W/mK, 429W/mK next to silver, much higher than 237W/mK of aluminum) and good economic benefits (copper 6.52USD/kg costs only 1.3% of silver 510.71 USD/kg). The advantages and the disadvantages of the microchannel copper heat sink (Microchannels Cu of Thermocore company) and the porous copper heat dissipation material (LCS pore Cu of Versarien company) which are commercially produced at present are obvious. Compared with the micro-channel copper heat sink, the porous copper has more heat dissipation area and higher heat exchange coefficient. However, the resistance of the fluid passing through the porous metal is relatively larger, the inlet pressure of the fluid is often more than 10 times of that of the micro-channel, a driving pump with larger power is needed to promote the flow of the internal refrigerant, and the energy consumption in use is greatly increased.

At present, the prior art also invents a heat dissipation structure adopting a plurality of layers of micro-channels. For example, the publication No. CN103745961B entitled "heat sink using lotus-shaped porous material micro-channel module" discloses a heat sink material structure of directional micro-channel, which adopts a metal-gas eutectic directional solidification method to prepare a multi-layer directional micro-channel. However, the directional microchannel heat sink in the prior art has limited length of the directional microchannel due to the limitation of the preparation process, the occupation ratio and distribution of the microchannel are difficult to control, the prepared heat dissipation device is generally formed by splicing a plurality of materials with the directional microchannel, the microchannel is discontinuous, the heat dissipation performance is improved limitedly, the preparation process is complex, and the cost is relatively high.

Disclosure of Invention

The invention provides a composite heat sink with a directional microchannel and a disordered hole and a preparation method thereof, aiming at least one technical problem in the prior art, the integral preparation process is simple, the manufacturing cost is low, the prepared heat sink is internally provided with a continuous microchannel and micropores for assisting heat exchange, and the heat dissipation performance is extremely excellent.

The technical scheme for solving the technical problems is as follows: the utility model provides a directional microchannel and unordered hole composite heat sink, includes heat sink body, be provided with a plurality of microchannels that link up whole heat sink body along the syntropy on the heat sink body, still be provided with a plurality of micropores between a plurality of microchannels of heat sink body.

On the basis of the technical scheme, the invention can be further improved as follows.

Further, the plurality of micro channels are communicated with each other through the micro holes.

Further, the heat sink body is made of a heat-conducting metal material.

Preferably, the heat sink body is made of copper, nickel-based alloy or steel.

Further, the micro-channel volume accounts for 30-70% of the heat sink body.

Preferably, the micro-channel volume accounts for 40-60% of the heat sink body.

Furthermore, the diameter of the micro-channel is 50-1000 μm.

Preferably, the diameter of the micro-channel is 100-800 μm.

Furthermore, the aperture of the micropore is 50-1000 μm.

Furthermore, the aperture of the micropore is 100-500 mu m.

Further, the volume of the micro-pores accounts for 20-70% of the heat sink body.

Preferably, the volume of the micropores accounts for 30-60% of the heat sink body.

The invention also designs a manufacturing method of the composite heat sink, which comprises the following steps:

s1 preparation of slurry: weighing the components according to the following volume percentage, and uniformly mixing, wherein 20-70% of metal or metal oxide powder, 20-70% of filling powder and 2-15% of binder are used for obtaining slurry;

s2 brushing slurry and filling wire: embedding thermoplastic high polymer material filling wires in the slurry prepared in the step S1 according to the orientation direction, and paving the filling wires in a heat sink shell or a heat sink mold to prepare a heat sink blank;

s3 drying and forming: drying and solidifying the heat sink blank prepared in the step S2 in the atmosphere to prepare a blank;

s4 pre-sintering in atmosphere: pre-sintering the blank prepared in the step S3 in an atmospheric environment, and cooling to room temperature after sintering to prepare an oxidized metal blank with a directional microchannel;

s5 sintering and reducing: and sintering and reducing the oxidized metal blank with the directional micro-channel prepared in the step S4 in vacuum or reducing atmosphere, and cooling to room temperature after sintering and reducing to prepare the composite heat sink.

Further, in step S1, the metal or metal oxide powder is a powder of a metal such as copper, nickel-based alloy, or steel, or an oxide powder thereof.

Further, the filler powder is a solid organic powder or an inorganic powder having a vaporization temperature not higher than a pre-sintering temperature, and in step S2, the filler filaments of the thermoplastic polymer material are filler filaments of the thermoplastic polymer material having a vaporization temperature not higher than the pre-sintering temperature.

Further, in the step S1, the metal or metal oxide powder is contained in an amount of 30 to 60% by volume.

Further, in the step S1, the particle size of the metal or metal oxide powder is 20 to 300 μm.

Further, in the step S1, the filling powder is selected from one or more of PLA, PP, acryl or urea.

Further, in the step S1, the filling powder is 30 to 60% by volume.

Further, in the step S1, the filler powder has a particle size of 50 to 1000 μm.

Preferably, in the step S1, the filler powder has a particle size of 100 to 500 μm.

Further, in the step S1, the binder is selected from alcohol, PVA, or vaseline, and the binder is 5 to 10% by volume.

Further, in step S2, the thermoplastic polymer filling filament is a plastic filament such as PLA, PP, or ABS.

Further, in the step S2, the volume percentage of the slurry and the filling yarn is 30-70% of the slurry and 30-70% of the filling yarn.

Preferably, in the step S2, the volume percentage of the sizing agent and the filling yarn is 40-60% of the sizing agent and 40-60% of the filling yarn.

Further, in the step S2, the diameter of the filling wire is 50-1000 μm.

Preferably, in the step S2, the filler wire has a diameter of 100 to 800 μm.

Further, in the step S4, the pre-sintering is performed by uniformly raising the temperature from room temperature to 400 to 600 ℃ and maintaining the temperature for more than 1 hour.

Preferably, in the step S4, the uniform temperature increase from room temperature is performed at a temperature increase rate of 10 ℃ per minute.

Further, in the step S5, when the sintering reduction is performed in a vacuum atmosphere, the vacuum pressure is less than 10Pa, and the temperature needs to be uniformly raised from room temperature to 800-950 ℃ and kept for 5-7 hours; and when the sintering reduction is carried out in a reducing atmosphere, uniformly heating the mixture from room temperature to 500-950 ℃, and preserving the heat for 0.5-3 h.

Preferably, in the step S5, the uniform temperature increase from room temperature is performed at a temperature increase rate of 10 ℃ per minute.

Preferably, in step S5, when the sintering is performed in a reducing atmosphere, the reducing gas is pure hydrogen or a mixed gas of hydrogen and nitrogen; when the reducing gas is a mixed gas of hydrogen and nitrogen, the content of the hydrogen is 10-70%.

The invention has the following beneficial effects:

1) the heat sink cooling liquid prepared by the invention has small flow resistance, simple manufacturing process and low manufacturing cost.

2) According to the composite heat sink, the internal directional micro-channel is a continuous channel, the proportion and distribution of the micro-channel can be controlled by adjusting the proportion and the coating mode of the filling wires according to requirements, the heat sink with densely arranged micro-channels can be prepared, the preparation process is very convenient, and the overall heat dissipation performance is extremely excellent.

3) The composite heat sink has the advantages that the micro-pores are arranged among the micro-channels for auxiliary heat exchange, so that the heat dissipation performance is further improved, and the composite heat sink has a good application prospect in various fields of micro-electronic equipment, solar heat transmission, spacecraft heat transfer and heat dissipation and the like.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic cross-sectional view of the present invention;

FIG. 3 is a microscope image of the internal structure of the present invention;

in the drawings, the components represented by the respective reference numerals are listed below:

1. heat sink, 2, microchannel.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Techniques are used to define: the gasification in the invention refers to the transformation from solid state to gas state, including physical or chemical transformation such as pyrolysis gasification and sublimation.

As shown in fig. 1 to 3, the directional microchannel and disordered hole composite heat sink designed by the present invention includes a heat sink body 1, a plurality of microchannels 2 penetrating through the whole heat sink body are arranged on the heat sink body 1 along the same direction, and a plurality of micropores are further arranged between the plurality of microchannels 2 of the heat sink body.

Preferably, the plurality of microchannels 2 of the present invention are in communication with each other through micropores.

In a more preferred embodiment, the micro-channels 2 occupy 30 to 70% of the volume of the heat sink body.

Preferably, the micro-channel 2 occupies 40-60% of the heat sink body in volume.

In a more preferred embodiment, the diameter of the microchannel 2 is 50 to 1000 μm.

Preferably, the diameter of the micro-channel 2 is 100-800 μm.

In a more preferred embodiment, the pore diameter of the micropores is 50 to 1000 μm.

Preferably, the pore diameter of the micropores is 100-500 μm.

In a more preferred embodiment, the volume of the micro pores is 20 to 70% of the heat sink body.

The core of the invention is that the directional micro-channel 2 is configured in the heat sink, and a plurality of micropores are arranged to communicate the directional micro-channel 2. The structural design of the invention can utilize the synergistic effect of the micro-channel 2 and the micro-hole to achieve the purpose of improving the heat dissipation performance of the heat sink. According to the speculation of the inventor, after the structural design of the invention is adopted, when the heat sink dissipates heat, the micro channels 2 can form convection of a heat dissipation medium through the micro holes, and through the convection, the heat dissipation medium is utilized to rapidly transfer heat, so that the heat exchange efficiency is greatly improved. The inventor also speculates that after the micropores are arranged, the inner wall of the microchannel 2 is in a non-smooth state and has dense granular bulges and depressions, so that the heat exchange medium can form turbulent flow when passing through the microchannel 2, and the existence of the turbulent flow can effectively improve the heat exchange efficiency of the heat sink. Finally, due to the existence of the micropores, the specific surface area of the heat sink can be greatly improved, and the heat exchange efficiency can also be improved by improving the specific surface area.

The invention adopts a special preparation process, and concretely comprises the following steps:

The metal or metal oxide powder of the present invention may be selected from powders of metals such as copper, nickel-based alloys, or steel, or oxide powders thereof. Copper, which is excellent in thermal conductivity, is preferably used. The thermal conductivity of copper in all metals is 403W/mK, 429W/mK second only to silver, and much higher than 237W/mK of aluminum. Whereas the price of copper $ 6.52/kg is only 1.3% of $ 510.71/kg for silver in terms of cost. The choice of copper as the production material is clearly the best choice. When the volume of the micropores accounts for a large proportion, the heat dissipation of the metal is basically replaced by phase change heat transfer and medium heat transfer, so that other metal materials are also suitable for preparing the heat sink.

At present, the porous heat sink can be prepared by casting or sintering and the like. The porous metal heat sink prepared by casting needs to be added with a foaming agent in casting metal liquid to realize porous foaming, while the porous metal heat sink prepared by sintering generally adopts metal fibers, a metal wire mesh or metal powder with certain particle size as raw materials, and is sintered in a powder metallurgy manner to obtain a porous material with higher porosity. The casting method and the direct metal powder sintering method have low utilization rate because the two methods are difficult to control the size of pores and the prepared heat sink has overlarge fluid resistance and is difficult to meet the requirement.

At present, the preparation of the directional microchannel heat sink is mainly prepared by adopting a metal-gas eutectic directional solidification mode. For the heat sink, the main preparation methods of the micro-channel are etching, micro-milling, 3D printing and a metal-gas eutectic directional solidification method. The etching and micro-milling can only be carried out on the surface, and the method has the advantages that the fluid channel can be optimized, the performance optimization design is carried out on a single channel, the fluid resistance is reduced, and the heat exchange coefficient is increased, but the defects that the number of the channels and the heat dissipation specific surface area are limited. The metal-gas eutectic directional solidification method can prepare a multi-layer straight microchannel structure in the material, greatly increases the number of channels and the heat dissipation specific surface area, and can control the diameter of the microchannel to a certain extent, but has the defects that the length of the channels is limited, generally not more than 20mm, the channels cannot be arranged in a controllable way, the distribution randomness is large, the port of each channel is closed, and the channels must be separated by using a wire cutting technology before being used as a heat sink. The existing mature 3D printing technology still needs to break through the preparation precision of micropores and microchannels, when the laser 3D printing is used for preparing the microchannels, powder in the microchannels is partially sintered together due to a laser heat affected zone to block the channels, and meanwhile, it is quite difficult to take out the filling metal powder from the microchannels formed after laser cladding. Thus, the manner of directional solidification of the metal-gas eutectic is currently the best way. The prior art does not adopt an ablation method to prepare the micro-channel, mainly because the thermoplastic polymer ablation material is gasified basically at 300 ℃, and at the temperature, the metal powder cannot be sintered and molded and can collapse in a sintering furnace.

Due to the principle and existing problems of the metal-gas eutectic directional solidification method, the length of the heat sink is generally not more than 80 mm. For example, in the case of the "GASAR porous Cu-Cr alloy prepared by metal-hydrogen eutectic directional solidification", the length of the finally prepared micropores is about 60mm, and in the case of the "research on preparing lotus-shaped porous metal by metal-hydrogen eutectic directional solidification", the cast ingot prepared by finally taking Mg as a base material is only 40mm high. In the above mentioned article, the preparation is basically completed in a laboratory, and considering the difference between the industrial production and the laboratory, the length of the preparation in the industrial mass production is far lower than the preparation result in the ideal state of the laboratory.

In contrast, in the present invention, the inventors have found that when pre-sintered, the metal is first oxidized in the presence of oxygen to form an oxide. In this case, at a temperature of 200 to 300 ℃, weak connection between the metal oxide powders can be formed, and the blank can maintain its shape without collapsing. And then the temperature is continuously increased to 400-600 ℃, the connection strength of the weak connection can be continuously enhanced, and the process requirement is further met. The above findings allow the inventors to use ablation to fabricate composite heat sinks. The composite heat sink prepared by the method has the advantages that the size, the aperture, the hole ratio and the like can be accurately controlled, even the distribution of micro-channels can be accurately controlled, and the preparation cost is far lower than that of a metal-gas eutectic directional solidification method.

In a more preferred embodiment, in step S1, the filler powder is a solid organic powder or an inorganic powder having a vaporization temperature equal to or lower than a pre-sintering temperature; in step S2, the thermoplastic polymer material filling yarns are thermoplastic polymer material filling yarns whose vaporization temperature is lower than or equal to the pre-sintering temperature.

In principle, any solid organic or inorganic powder having a vaporization temperature below the pre-sintering temperature, as well as filled filaments of thermoplastic polymer material, can be used in the present invention.

However, considering environmental protection, cost, instantaneous internal pressure during gasification, and other factors, the cost is low in order to ensure better environmental protection, and the instantaneous internal pressure during gasification can ensure a weak bonding force lower than that of the metal oxide powder and can ensure that the metal oxide powder does not collapse during pre-sintering. Thus, the filler powder is preferably selected from one or a combination of more than one of PLA, PP, acryl or urea. And the filling silk of the carbon-based material is preferably selected from plastic silk such as PLA, PP or ABS. The instantaneous internal pressure during gasification is the key to material selection, and excessive instantaneous gasification pressure can destroy weak connection between metal oxide powders, and cause local collapse or deformation of blanks (such as blockage of partial micro-channels). The above material selection was experimentally selected by the inventors from a wide range of materials.

In a more preferred embodiment, in the step S1, the metal or metal oxide powder is 30 to 60 volume%.

Organic polymer thermoplastic or inorganic crystal powder is mixed and then is made into pulp, better molding can be ensured firstly, and the finally prepared metal core layer 1 belongs to foamed metal and has more excellent heat dissipation performance. However, it has been found through experimental studies that the strength of the pre-sintered oxidized metal core blank gradually decreases as the content of the metal or metal oxide powder decreases, and when the content of the metal or metal oxide powder is less than 20%, the pre-sintered oxidized metal core blank partially collapses or collapses. Meanwhile, after the heat sink finally manufactured is tested for heat dissipation performance, the heat dissipation performance is gradually improved when the content of the metal or metal oxide powder is gradually improved from 20%, and the trend of the improvement reaches a peak at 60%, and then the heat dissipation performance begins to be reduced. When the content of the metal or metal oxide powder is gradually increased from 20% to 30%, the heat dissipation performance is uniformly increased, the increasing trend tends to be gentle in the range of 30% -60%, the heat dissipation performance begins to be reduced after the increasing trend exceeds 60%, and the heat dissipation performance is reduced at a higher speed after the increasing trend exceeds 70%. Therefore, the content of the metal or metal oxide powder is preferably controlled to be 30-60% in consideration of the combination of the manufacturing difficulty and the heat dissipation performance.

The inventor conjectures that the heat dissipation performance and the content of metal or metal oxide powder are in the above-mentioned correlation through experimental data, and the heat dissipation performance and the content of metal or metal oxide powder are supposed to be that when the content of metal is controlled to be 30-60%, the number of micropores among the microchannels 2 is sufficient, and the flow of a heat exchange medium can be formed among the channels, so that the synergistic heat exchange is generated, heat is quickly dissipated to a far place away from a heat source, and the heat exchange efficiency is improved; when the content of the metal or metal oxide powder is too low (< 20%), the content of the metal is too low, so that the heat conduction efficiency is reduced, and the overall heat dissipation efficiency is affected; when the content of the metal or metal oxide powder exceeds 70%, the number of micropores between the channels is too small, and the flow of the heat exchange medium between the channels is sharply reduced, resulting in a sharp drop in the efficiency of the cooperative heat exchange, so that the heat radiation performance is rapidly reduced.

Correspondingly, the content of the filling powder in percentage by volume is preferably controlled to be 30-60%.

In a more preferred embodiment, in step S1, the binder is preferably selected from alcohol, PVA, or vaseline, and the binder is 5 to 10% by volume. The adhesive has good bonding effect and is easy to remove. When the content of the binder is less than 5%, the bonding effect is extremely poor, and the removal difficulty is increased due to the excessive addition amount of the binder, so that the volume percentage content of the binder is preferably controlled to be 5-10%.

In a more preferred embodiment, in the step S1, the particle size of the metal or metal oxide powder is 20 to 300 μm.

The core of the invention is that the metal oxide powder can generate enough weak binding force when being sintered at low temperature, so as to ensure that other substances except the metal oxide powder can be removed when being pre-sintered, and simultaneously ensure that the oxidized metal core blank cannot collapse. According to the analysis of the experimental research results by the inventors, when the particle size of the powder exceeds 1mm, the heat dissipation performance is poor. The inventors speculate that the powder particles have an excessively large particle size, and that large gaps exist between the powder particles during sintering, and the size of the gaps exceeds the diameter of the microchannel 2, which is not favorable for forming a microporous structure capable of promoting fluid turbulence, and greatly reduces the solid-liquid contact area and the heat dissipation area of the material. The inventors reasonably speculate that the solid-liquid contact area and the heat dissipation area of the heat sink material have a relatively large correlation with the powder particle size, and the larger the powder particle size is, the smaller the area is. The smaller the particle size is, the higher the cost is, and the particle size is preferably controlled to be 20-300 mu m based on the comprehensive consideration of cost and bonding force.

In a more preferred embodiment, in the step S1, the filler powder has a particle size of 50 to 1000 μm. The particle size can effectively reduce the thickness of metal intervals among the channels, and is favorable for improving the heat dissipation performance.

In a more preferred embodiment, in the step S2, the volume percentage of the slurry and the filling yarn is 30 to 70% of the slurry and 30 to 70% of the filling yarn.

In a more preferred embodiment, in the step S2, the diameter of the filler wire is 50 to 1000 μm.

In the invention, the larger the content of the filling wires is, the denser the micro-channels 2 are, and the higher the heat dissipation efficiency is. However, experimental studies show that the strength of the pre-sintered oxidized metal core blank is gradually reduced with the increase of the content of the filler wire, and when the content of the filler wire is higher than 70%, the pre-sintered oxidized metal core blank is locally collapsed or collapsed, and meanwhile, the content of the filler is too high, which causes the reduction of the metal content, so that the heat conduction performance of the heat sink base body is reduced, and the heat dissipation effect is deteriorated. If the content of the filler wire is too low, the heat dissipation performance is reduced. Therefore, the content of the filler filaments is preferably controlled to be 30 to 70%. Just because of the special preparation process of the present invention, the micro-channel proportion can only be over 60%, and the preparation of such dense micro-channels 2 is difficult to realize by other methods.

While the diameter of the filler wire determines the pore size of the final microchannel 2. The aperture is too small, the self adhesion of the heat dissipation medium can cause the steam at the evaporation end to be unable to pass through the micro-channel, and the flow rate of the heat dissipation medium can be influenced if the aperture is too large. After comprehensive consideration, the diameter of the filling wire is preferably 50-1000 μm.

In a more preferred embodiment, in step S4, the pre-sintering is performed at a temperature increase rate of 10 ℃ per minute from room temperature to 400 ℃ to 600 ℃ for 1 hour or more.

The core of the invention lies in the pre-sintering step, whether the metal core layer 1 with better quality can be prepared depends on whether the non-metallic oxide material can be completely removed in the pre-sintering process, and the shape of the oxidized metal core blank can be maintained. The control of the presintering temperature is therefore particularly critical and is the core of the invention. After repeated experimental research by the inventor, the oxidized metal core blank with the best quality can be obtained by adopting the better pre-sintering parameters, the impurity removal rate can reach 100%, and meanwhile, the shape can be kept to be 100% intact.

In a more preferred embodiment, in the step S5, when the sintering reduction is performed in a vacuum atmosphere, the vacuum pressure is less than 10Pa, and the temperature is maintained for 5 to 7 hours from the room temperature to 800 to 950 ℃ at a temperature rise rate of 10 ℃ per minute; and when the sintering reduction is carried out in a reducing atmosphere, the temperature is raised from room temperature to 500-950 ℃ at the heating rate of 10 ℃ per minute, and the temperature is kept for 0.5-3 h.

In a more preferred embodiment, in step S5, when the sintering is performed in a reducing atmosphere, the reducing gas is pure hydrogen or a mixed gas of hydrogen and nitrogen; when the reducing gas is a mixed gas of hydrogen and nitrogen, the content of the hydrogen is 10-70%.

Example 1

The embodiment provides a copper heat sink with a directional microchannel and a disordered porous composite structure

Preparing slurry: weighing copper powder, urea powder and a binder PVA white glue according to the following volume percentage, and uniformly mixing the components, 60 percent of copper powder (with the average particle diameter of 100 mu m), 30 percent of urea powder (with the average particle diameter of 50 mu m) and 10 percent of binder PVA white glue to obtain slurry.

Filling the slurry and the filling wires into the heat sink shell: filling wire PLA filaments (diameter 1000 μm) are embedded into the mixed slurry according to the orientation direction and are laid inside the heat sink shell. The volume percentage of the slurry and the filling wires is as follows, 70 percent of the slurry, 30 percent of the filling wires and the heat sink shell are copper shells.

Drying and forming: and after the slurry and the filling wire are filled into the heat sink shell, drying and solidifying the slurry and the filling wire in the atmosphere to form a blank.

Pre-sintering in the atmosphere: drying the formed blank, placing the blank in a muffle furnace, and preserving heat for one hour from room temperature to 500 ℃ at a heating rate of 10 ℃ per minute in an atmospheric environment, wherein copper powder can be oxidized by heating in an air environment, the oxidized copper powder can form weak connection before the filling material is decomposed, the filling material urea powder and PLA filaments start to be decomposed when the temperature reaches 200 ℃, and a stable copper oxide blank can be formed by preserving heat for one hour at 500 ℃.

Sintering and reducing: reducing the copper oxide blank in vacuum, keeping the temperature of 850 ℃ for 5-7 hours from the room temperature at the temperature rising rate of 10 ℃ per minute with the vacuum pressure of less than 10Pa, and cooling the copper oxide blank to the room temperature along with the furnace.

And installing a heat sink water inlet and outlet interface.

The diameter of the oriented micro-channel in this example is 1000 μm, the volume ratio of the micro-channel is 30%, the average pore size of the disordered porous is 50 μm, and the volume ratio of the disordered porous is 30%. In the directional microchannel and the disordered porous composite structure heat sink, the cooling liquid can flow from the directional microchannel, and can realize the interaction of fluids in the adjacent microchannels through convection in the disordered porous in the microchannel wall, so that the heat conduction effect of the auxiliary metal can quickly transfer the heat to the channels at different positions away from the heat source, and the heat exchange performance of the heat sink is greatly enhanced.

Example 2

Preparing slurry: weighing copper oxide powder, PP powder and vaseline serving as a binder according to the following volume percentage, and uniformly mixing the components, wherein the copper oxide powder accounts for 30 percent (the average particle diameter is 20 mu m), the PP powder accounts for 60 percent (the average particle diameter is 100 mu m), and the vaseline accounts for 10 percent to obtain slurry.

Filling the slurry and the filling wires into the heat sink shell: filling wires (with the diameter of 800 mu m) of ABS (acrylonitrile butadiene styrene) are embedded into the mixed slurry according to the orientation direction and are laid inside the heat sink shell. The volume percentage of the slurry and the filling wire is as follows, 40 percent of the slurry, 60 percent of the filling wire and the heat sink shell are copper shells.

Pre-sintering in the atmosphere: and (3) placing the dried and formed blank in a muffle furnace, wherein copper oxide powder can form weak connection under an air ring before the filler material is decomposed, the filler PP powder and the ABS wire start to be decomposed when the temperature reaches above 200 ℃, and the blank is subjected to heat preservation at 500 ℃ for one hour to form a stable copper oxide blank.

Sintering and reducing: and (3) reducing and sintering the copper oxide blank in an atmosphere reducing furnace, wherein the reducing gas is hydrogen content of 50% in hydrogen-nitrogen mixed gas, and the temperature is increased from room temperature to 700 ℃ at a temperature rise rate of 10 ℃ per minute. Keeping the temperature for 2 hours, and then cooling the mixture to room temperature along with the furnace.

And installing a heat sink water inlet and outlet interface.

The diameter of the oriented micro-channel in this example is 800 μm, the volume ratio of the micro-channel is 60%, the average pore size of the disordered porous is 100 μm, and the volume ratio of the disordered porous is 60%. In the directional microchannel and the disordered porous composite structure heat sink, the cooling liquid can flow from the directional microchannel, and can realize the interaction of fluids in the adjacent microchannels through convection in the disordered porous in the microchannel wall, so that the heat conduction effect of the auxiliary metal can quickly transfer the heat to the channels at different positions away from the heat source, and the heat exchange performance of the heat sink is greatly enhanced.

Example 3

The embodiment provides a nickel-based alloy heat sink with a directional microchannel and a disordered porous composite structure

Preparing slurry: weighing nickel-based alloy or nickel oxide-based alloy powder, acrylic powder and binder alcohol according to the following volume percentage, and uniformly mixing, wherein the slurry is obtained by 70% of nickel-based alloy or nickel oxide-based alloy powder (with the average particle diameter of 500 microns), 20% of acrylic powder (with the average particle diameter of 100 microns) and 10% of binder alcohol.

Filling the slurry and the filling wires into the heat sink shell: filling wire PLA filaments (diameter 100 μm) are embedded in the mixed slurry according to the orientation direction and are laid in a heat sink mould. The volume percentage of the slurry and the filling wire is as follows, 30 percent of the slurry, 70 percent of the filling wire and the heat sink shell are nickel-based alloy shells.

Pre-sintering in the atmosphere: drying the formed blank, placing the blank and a die in a muffle furnace, wherein the nickel-based alloy or nickel oxide-based alloy powder can form weak connection under an air ring before the filler is decomposed, the filler acrylic powder and the PLA wire start to be decomposed when the temperature reaches 200 ℃, and after heat preservation for one hour at 650 ℃, demoulding can form a stable nickel oxide-based alloy blank.

Sintering and reducing: reducing and sintering the nickel oxide base alloy blank in an atmosphere reducing furnace, wherein the reducing gas is hydrogen, and the temperature is increased from room temperature to 1200 ℃ at the temperature increase speed of 10 ℃ per minute. Keeping the temperature for 1 hour, and then cooling to room temperature along with the furnace.

And installing a heat sink water inlet and outlet interface.

The diameter of the oriented micro-channel in this example is 100 μm, the volume ratio of the micro-channel is 70%, the average pore size of the disordered porous is 500 μm, and the volume ratio of the disordered porous is 20%. In the directional microchannel and the disordered porous composite structure heat sink, the cooling liquid can flow from the directional microchannel, and can realize the interaction of fluids in the adjacent microchannels through convection in the disordered porous in the microchannel wall, so that the heat conduction effect of the auxiliary metal can quickly transfer the heat to the channels at different positions away from the heat source, and the heat exchange performance of the heat sink is greatly enhanced.

Example 4

The embodiment provides a directional microchannel and disordered porous composite structure steel heat sink

Preparing slurry: weighing steel or oxidized steel powder, urea powder and a binder PVA white glue according to the following volume percentage, and uniformly mixing, wherein 20% of the steel or oxidized steel powder (with the average particle diameter of 300 microns), 70% of the urea powder (with the average particle diameter of 1000 microns) and 10% of the binder PVA white glue to obtain slurry.

Filling the slurry and the filling wires into the heat sink shell: filling wire PLA filaments (diameter 50 μm) are embedded into the mixed slurry according to the orientation direction and are laid inside the heat sink shell. The volume percentage of the slurry and the filling wire is as follows, 60 percent of the slurry, 40 percent of the filling wire and the heat sink shell are steel shells.

Pre-sintering in the atmosphere: drying the formed blank, placing the blank in a muffle furnace, forming weak connection between steel or oxidized steel powder under an air ring before the filler is decomposed, decomposing the filler urea powder and PLA filaments when the temperature reaches 200 ℃, and preserving the heat at 650 ℃ for 30 minutes to form a stable oxidized steel blank.

Sintering and reducing: reducing and sintering the oxidized steel blank in an atmosphere reducing furnace, wherein the reducing gas is hydrogen, and the temperature is increased from room temperature to 900 ℃ at the temperature increase speed of 10 ℃ per minute. Keeping the temperature for 2 hours, and then cooling the mixture to room temperature along with the furnace.

And installing a heat sink water inlet and outlet interface.

The diameter of the oriented micro-channel in this example is 50 μm, the volume ratio of the micro-channel is 40%, the average pore size of the disordered porous is 1000 μm, and the volume ratio of the disordered porous is 70%. In the directional microchannel and the disordered porous composite structure heat sink, the cooling liquid can flow from the directional microchannel, and can realize the interaction of fluids in the adjacent microchannels through convection in the disordered porous in the microchannel wall, so that the heat conduction effect of the auxiliary metal can quickly transfer the heat to the channels at different positions away from the heat source, and the heat exchange performance of the heat sink is greatly enhanced.

Example 5

Preparing slurry: weighing copper powder, PLA powder and a binding agent PVA white glue according to the following volume percentage, and uniformly mixing, 40% of copper powder (with the average particle diameter of 150 mu m), 50% of PLA powder (with the average particle diameter of 300 mu m) and 10% of binding agent PVA white glue to obtain slurry.

Filling the slurry and the filling wires into the heat sink shell: filling PP wires (with the diameter of 500 mu m) are embedded into the mixed slurry according to the orientation direction and are laid inside the heat sink shell. The volume percentage of the slurry and the filling wires is as follows, 50 percent of the slurry, 50 percent of the filling wires and the heat sink shell are copper shells.

Pre-sintering in the atmosphere: and (2) drying the formed blank, placing the blank in a muffle furnace, and preserving heat for one hour from room temperature to 500 ℃ at a heating rate of 10 ℃ per minute in an atmospheric environment, wherein copper powder can be oxidized by heating in an air environment, the oxidized copper powder can form weak connection before the filling material is decomposed, the filling material PLA powder and PP wire begin to decompose when the temperature reaches 200 ℃, and a stable copper oxide blank can be formed by preserving heat for one hour at 500 ℃.

And installing a heat sink water inlet and outlet interface.

The diameter of the oriented micro-channel of this example was 500 μm, the volume ratio of the micro-channel was 50%, the average pore size of the disordered porous membrane was 300 μm, and the volume ratio of the disordered porous membrane was 50%. In the directional microchannel and the disordered porous composite structure heat sink, the cooling liquid can flow from the directional microchannel, and can realize the interaction of fluids in the adjacent microchannels through convection in the disordered porous in the microchannel wall, so that the heat conduction effect of the auxiliary metal can quickly transfer the heat to the channels at different positions away from the heat source, and the heat exchange performance of the heat sink is greatly enhanced.

Example 6

The embodiment provides a copper-zinc alloy heat sink with a directional microchannel and a disordered porous composite structure

Preparing slurry: weighing copper-zinc alloy or copper-zinc oxide alloy powder, PP powder and binder vaseline according to the following volume percentage, and uniformly mixing, wherein 50% of copper-zinc alloy or copper-zinc oxide alloy powder (with the average particle diameter of 180 mu m), 40% of PP powder (with the average particle diameter of 700 mu m) and 10% of binder vaseline are used for obtaining slurry.

Filling the slurry and the filling wires into the heat sink shell: filling wires ABS wires (diameter 400 μm) are embedded into the mixed slurry according to the orientation direction and are laid in a heat sink mould. The volume percentage of the slurry and the filling wires is as follows, 450 percent of the slurry, 55 percent of the filling wires and the heat sink shell are copper-zinc alloy shells.

Pre-sintering in the atmosphere: and (3) drying the formed blank, placing the blank and a die in a muffle furnace, wherein the copper-zinc alloy or copper-zinc oxide alloy powder can form weak connection under an air ring before the filler is decomposed, the filler PP powder and the ABS wire start to be decomposed when the temperature reaches 200 ℃, preserving heat for 30 minutes at 650 ℃, and demoulding to form a stable copper-zinc oxide alloy blank.

Sintering and reducing: reducing and sintering the copper oxide zinc alloy blank in an atmosphere reducing furnace, wherein the reducing gas is hydrogen, and the temperature is increased from room temperature to 890 ℃ at the temperature rising speed of 10 ℃ per minute. Keeping the temperature for 2.5 hours, and then cooling to room temperature along with the furnace.

And installing a heat sink water inlet and outlet interface.

The diameter of the oriented micro-channel in this example is 400 μm, the volume ratio of the micro-channel is 55%, the average pore size of the disordered porous is 700 μm, and the volume ratio of the disordered porous is 40%. In the directional microchannel and the disordered porous composite structure heat sink, the cooling liquid can flow from the directional microchannel, and can realize the interaction of fluids in the adjacent microchannels through convection in the disordered porous in the microchannel wall, so that the heat conduction effect of the auxiliary metal can quickly transfer the heat to the channels at different positions away from the heat source, and the heat exchange performance of the heat sink is greatly enhanced.

The micro-channel copper heat sink processed by single-layer micro milling in the background art is taken as a comparative example 1, the porous copper heat sink in the background art is taken as a comparative example 2, the heat sinks of the

embodiments

1, 2 and 5 of the invention are taken as examples (since the comparative examples adopt copper as a material, the same material is adopted for comparison), the heat exchange coefficient and the inlet pressure are detected, and the obtained results are shown in table 1.

Table 1 table of main performance parameters in forced convection heat dissipation of heat sink

As can be seen from the results in Table 1, the heat sink of comparative example 1 has a limited heat dissipation area due to the use of only a single-layer microchannel, and thus has a low heat transfer coefficient of 20000W/m²k is about. Comparative example 2 porous heat sink heat dissipation area is big, and the heat transfer coefficient is better, but because its fluid resistance is great, and the inlet pressure is up to more than 200kPa, is difficult to be used in the actual production. In the embodiment of the invention, the micro-channels 2 are directional and continuous, so the inlet pressure is lower, meanwhile, the special heat dissipation structure of the micro-channels 2 in cooperation with the micro-holes is adopted, the micro-channels 2 can form the flow of a heat dissipation medium by the micro-holes, the heat dissipation efficiency is obviously improved, and the heat exchange coefficient can reach 30000W/m²k is more than k. Compared with the prior art, the heat sink provided by the invention has the advantage that the performance is remarkably improved by combining the comparison results of two core parameters of inlet pressure and heat exchange coefficient.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A directional microchannel and disordered hole composite heat sink comprises a heat sink body (1), and is characterized in that: the heat sink body (1) is provided with a plurality of micro-channels (2) penetrating through the whole heat sink body (1) along the same direction, and a plurality of micro-holes are further arranged among the micro-channels (2) of the heat sink body (1).

2. A directional microchannel and random hole composite heat sink in accordance with claim 1, wherein: the plurality of micro channels (2) are communicated with each other through micropores.

3. A directional microchannel and random hole composite heat sink in accordance with claim 1, wherein: the heat sink body (1) is made of a heat-conducting metal material.

4. A directional microchannel and random hole composite heat sink in accordance with claim 3, wherein: the heat sink body (1) is made of copper, nickel-based alloy or steel.

5. A directional microchannel and random hole composite heat sink in accordance with claim 1, wherein: the micro-channel (2) occupies 30-70% of the heat sink body (1) in volume.

6. A directional microchannel and random hole composite heat sink in accordance with claim 5, wherein: the micro-channel (2) occupies 40-60% of the heat sink body (1) in volume.

7. A directional microchannel and random hole composite heat sink in accordance with claim 1, wherein: the diameter of the micro-channel (2) is 50-1000 mu m.

8. A directional microchannel and random hole composite heat sink in accordance with claim 7, wherein: the diameter of the micro-channel (2) is 100-800 μm.

9. A directional microchannel and random hole composite heat sink in accordance with claim 1, wherein: the aperture of the micropores is 50-1000 mu m.

10. A directional microchannel and random hole composite heat sink in accordance with claim 9, wherein: the aperture of the micropore is 100-500 mu m.

11. A directional microchannel and random hole composite heat sink in accordance with claim 1, wherein: the volume of the micropores accounts for 20-70% of the heat sink body (1).

12. A directional microchannel and random hole composite heat sink in accordance with claim 11, wherein: the volume of the micropores accounts for 30-60% of the heat sink body (1).

13. The method for preparing the composite heat sink with the oriented micro-channels and the disordered holes as claimed in claims 1 to 12, characterized by comprising the following steps:

14. The method of claim 13, wherein the method comprises the steps of: in step S1, the metal or metal oxide powder is a powder of a metal such as copper, nickel-based alloy, or steel, or an oxide powder thereof.

15. The method of claim 13, wherein the method comprises the steps of: the filling powder is solid organic powder or inorganic powder with a vaporization temperature below the pre-sintering temperature, and in step S2, the filling filament of the thermoplastic polymer material is a filling filament of a thermoplastic polymer material with a vaporization temperature below the pre-sintering temperature.

16. The method of claim 13, wherein the method comprises the steps of: in the step S1, the metal or metal oxide powder is 30 to 60% by volume.

17. The method of claim 13, wherein the method comprises the steps of: in the step S1, the particle size of the metal or metal oxide powder is 20 to 300 μm.

18. The method of claim 13, wherein the method comprises the steps of: in the step S1, the filling powder is selected from one or more of PLA, PP, acryl or urea.

19. The method of claim 13, wherein the method comprises the steps of: in the step S1, the filling powder is 30-60% by volume.

20. The method of claim 13, wherein the method comprises the steps of: in the step S1, the particle size of the filler powder is 50 to 1000 μm.

21. The method of claim 13, wherein the method comprises the steps of: in the step S1, the binder is selected from alcohol, PVA or vaseline, and the volume percentage content of the binder is 5-10%.

22. The method of claim 13, wherein the method comprises the steps of: in the step S2, the thermoplastic polymer filling filament is a plastic filament such as PLA, PP or ABS.

23. The method of claim 13, wherein the method comprises the steps of: in the step S2, the volume percentage of the slurry and the filling yarns is 30-70% of the slurry and 30-70% of the filling yarns.

24. The method of claim 23, wherein the method comprises the steps of: in the step S2, the volume percentage of the slurry and the filling yarn is 40-60% of the slurry and 40-60% of the filling yarn.

25. The method of claim 13, wherein the method comprises the steps of: in the step S2, the diameter of the filling wire is 50-1000 μm.

26. The method of claim 13, wherein the method comprises the steps of: in the step S4, the pre-sintering is required to be uniformly heated from room temperature to 400-600 ℃ and kept for more than 1 h.

27. The method of claim 14, wherein the method comprises the steps of: in the step S5, when the sintering reduction is carried out in a vacuum atmosphere, the vacuum pressure is less than 10Pa, and the temperature needs to be uniformly raised from room temperature to 800-950 ℃ and kept for 5-7 h; and when the sintering reduction is carried out in a reducing atmosphere, uniformly heating the mixture from room temperature to 500-950 ℃, and preserving the heat for 0.5-3 h.