CN113798496A

CN113798496A - Feeding and micro-channel heat sink and preparation method and application thereof

Info

Publication number: CN113798496A
Application number: CN202111088023.9A
Authority: CN
Inventors: 田威; 王长瑞
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2021-12-17

Abstract

The invention discloses a feeding and micro-channel heat sink and a preparation method and application thereof, belonging to the technical field of chip heat dissipation. The method comprises the following steps: carrying out surface treatment on the diamond particles, and cleaning the surfaces of the diamond particles; plating the plating element on the surface of the diamond particle to form a surface plating layer to obtain a plating layer diamond particle; uniformly mixing the diamond particles and the metal particles to obtain a mixed material, and placing the mixed material into mixing equipment for mixing; during mixing, adding a binder into mixing equipment according to a preset adding mode, and uniformly mixing; granulating to obtain a feed; the prepared feed is applied to the micro-channel heat sink. The invention adopts the ultrasonic auxiliary powder injection molding technology, breaks through the problems that the traditional powder injection is easy to generate defects such as air holes, hollows, cracks and the like, can eliminate the defects through ultrasonic vibration in the injection process, and ensures the compactness and uniformity of the injection blank; the manufacturing of the complex special-shaped micro-channel heat sink is realized through diffusion connection.

Description

Feeding and micro-channel heat sink and preparation method and application thereof

Technical Field

The invention belongs to the technical field of chip heat dissipation, and particularly relates to a feeding and micro-channel heat sink, and a preparation method and application thereof.

Background

The chip-level electronic equipment develops towards the directions of function integration, size miniaturization, compact structure and high power density, the heat flow density is greatly increased, and particularly the heat flow density of a core chip is increased from the traditional 200-300W/cm²Towards 1000W/cm²And (5) development. The ultrahigh heat flux density makes the thermal control problem of the chip prominent, the service life and the reliability of the chip are exponentially reduced, and the high-efficiency heat dissipation becomes the 'neck' problem of the chip.

The diamond-based feed has higher thermal conductivity coefficient (500W/m.K), 2-3 times of that of the traditional heat sink material, and low thermal expansion coefficient (matched with a novel core chip very much), and is one of the best novel heat sink materials; compared with the traditional flow channel, the special-shaped micro-channel structure has the advantages of low heat conduction resistance, high heat transfer coefficient, large specific surface area and the like, the heat exchange amount is high by 3 and more, the heat of the chip can be quickly transmitted, the temperature of the chip is reduced, and the problem of heat dissipation with ultrahigh heat flow density is solved. Therefore, the novel heat sink integrating the substrate, the packaging shell and the heat sink is manufactured by adopting the high-heat-conduction material, and the problem of ultrahigh heat flow density heat dissipation of the chip can be effectively solved by arranging the closed special-shaped heat dissipation micro-channel in the novel heat sink. However, how to realize the manufacture with low cost, high efficiency and high heat dissipation performance faces a difficult problem.

Disclosure of Invention

The invention provides a feeding and micro-channel heat sink, a preparation method and application thereof, aiming at solving the technical problems in the background technology.

The invention adopts the following technical scheme: a preparation method of feed comprises the following steps:

step one, carrying out surface treatment on diamond particles, and cleaning the surfaces of the diamond particles;

step two, plating surfaces on the surfaces of the diamond particles, and obtaining plated diamond particles by adopting a plating layer; including vacuum micro-evaporation, magnetron sputtering, and salt bath.

Step three, uniformly mixing the plated diamond particles and the metal particles to obtain a mixed material, and placing the mixed material into mixing equipment for mixing; during mixing, adding a binder into mixing equipment according to a preset adding mode, and uniformly mixing; and granulating to prepare the feed.

By adopting the technical scheme, the first step is to ensure that the surface of the diamond is clean and pollution-free; meanwhile, in order to improve the bonding force between the plated carbide and the surface of the diamond, the diamond is subjected to plating processes such as surface sensitization, activation, coarsening and the like to realize tight surface bonding of the carbide; and the second step aims to coat a nano-scale to micro-scale coating on the surface of the diamond particles, solve the problems of poor interface wettability, low bonding strength and the like of the diamond and metal elements such as copper, aluminum and the like, and ensure high heat-conducting property and adjustable linear expansion coefficient of the diamond-based feed.

In a further embodiment, the surface treatment in step one comprises: one or more working procedures of acid washing, alkali washing, boiling, surface cleaning and screening, wherein the treatment time of each working procedure is 5-30 min. Carry out nimble adjustment according to the in-service behavior to satisfy the demand of different products, improve the interface adsorptivity and the cleanliness factor of material.

In a further embodiment, the surface plating in step two comprises: one or more of a vacuum micro-evaporation method, a magnetron sputtering method and a salt bath method; the second step further comprises: and (4) carbonizing the coated diamond particles.

In a further embodiment of the method of the invention,

the plating elements include: w, Mo, Cr, Ti, Si, B, or WCx, MoCx, TiC, SiC, B₄At least one of C;

the metal particles include: metal powder or alloy powder; wherein the metal powder is at least one selected from Cu or Al; the alloy powder is selected from at least one of CuCr, AlTi or CuTi;

the adhesive comprises: one or more of polypropylene, polyethylene, paraffin, stearic acid or polyformaldehyde; the diamond particles with the grain size of 50-300 meshes are selected according to different products, and the requirements of different thicknesses and different heat conductivity coefficients can be met.

The feed prepared by the preparation method of the feed is applied to chip heat dissipation, and the high-efficiency heat dissipation of the chip is realized through a high-efficiency conduction and convection mode.

The micro-channel heat sink is prepared by adopting the feeding material and adopting the injection or/and welding process; the microchannel heat sink comprises: the heat sink body is provided with at least one accommodating part from top to bottom; the bottom of the heat sink body is provided with a plurality of horizontally arranged heat dissipation runners; the number and the shape of the heat dissipation flow channels are determined according to the heat dissipation requirement.

In a further embodiment, the following components are included: coating diamond particles, metal particles and a binder;

wherein the plating diamond particles comprise diamond particles, and a plating layer is plated on the surfaces of the diamond particles.

The preparation method for preparing the micro-channel heat sink at least comprises the following steps: and placing a preset die on an injection molding machine, injecting the molten feed into the die by the injection molding machine to form a blank, and performing densification, degreasing and sintering treatment on the blank to obtain the densified heat sink body. The micro-channel heat sink is manufactured by adopting powder injection molding, so that subsequent processing or less processing is avoided, the manufacturing efficiency can be effectively improved, and the cost is increased.

In a further embodiment, further comprising: when the feedstock is injected into the mold, an ultrasonic vibration device is used to act on the mold to promote flow of the molten feedstock. Eliminate the defects of air holes, hollowness, cracks and the like.

The preparation method for preparing the micro-channel heat sink at least comprises the following steps:

dividing the heat sink body into a plurality of areas according to the shape of the heat dissipation flow channel as required, wherein each area is provided with a corresponding sub-mold;

and preparing a plurality of sub heat sink bodies in each sub mold respectively, and assembling the sub heat sink bodies according to a preset typesetting in a welding and packaging mode. The method adopts a diffusion welding mode for welding and packaging, does not introduce other media, ensures the welding strength and the heat dissipation performance, and is suitable for an internal micro-channel with a complex structure inside the heat sink or which can not be realized by adopting an injection molding mold design.

Has the advantages that: the invention introduces ultrasonic auxiliary technology on the basis of the original diamond particle plating process, ensures that each layer can be plated with a uniform plating layer by continuously rolling the diamond particles through vibration in the plating process, and realizes the efficient and low-cost manufacture of the plated diamond particles.

The invention adopts the ultrasonic-assisted powder injection molding technology, breaks through the problems of easy generation of defects such as air holes, hollowness, cracks and the like in the traditional powder injection, can eliminate the defects through ultrasonic vibration in the injection process, and ensures the compactness and uniformity of the injection blank.

The invention realizes the welding and packaging of the partitioned micro-channel structure by the pulse current auxiliary diffusion welding method under the condition of not introducing a third material, reduces the interface thermal resistance and realizes high heat-conducting performance while ensuring the welding strength.

Drawings

FIG. 1 is a schematic view of a micro-channel heat sink of the chip of the present invention;

FIG. 2 is a schematic diagram of the micro flow channel heat sink design of the present invention;

FIG. 3 is a break diagram of the micro-channel heat sink of the present invention;

FIG. 4 is a schematic view of ultrasonic assisted powder injection molding of the micro-channel heat sink of the present invention;

FIG. 5 is a diagram of a micro-channel heat sink feed according to the present invention;

FIG. 6 is a schematic view of the manufacturing process of the micro flow channel heat sink of the present invention;

FIG. 7 is a schematic view of a microchannel heat sink vacuum diffusion bond of the present invention;

FIG. 8 is a schematic diagram of a micro-channel heat sink pulse current assisted diffusion connection according to the present invention;

FIG. 9 is a graph of the surface topography of diamond coated by vacuum micro-evaporation with the assistance of ultrasonic vibration according to the present invention;

FIG. 10 is a salt bath diamond plating surface topography of the present invention;

FIG. 11 is a surface topography of an ultrasonically assisted magnetron sputtered diamond of the present invention;

fig. 12 is a diagram of a plated diamond particle of the present invention after heat treatment.

Each label in the figure is: the heat sink comprises a heat sink body 1, an accommodating part 2, a bare chip 3, a heat dissipation runner 4, a fixed die 5, a movable die 6, an ultrasonic vibration device 7, a clamp 8, a vacuum diffusion welding furnace 9 and a heating electrode 10.

Detailed Description

The invention is further described with reference to the following examples and the accompanying drawings.

Chips such as IGBT, CPU, GPU, TR components and the like for military and civil electronic equipment such as 5G base stations, unmanned systems, LEDs, military radars, communication equipment and the like require miniaturization, high integration, high power and the like, and meanwhile, good heat dissipation performance is needed to ensure high reliability of the chips and use the chips later, so that how to perform efficient heat dissipation is important.

Example 1

The embodiment discloses a preparation method of a feed, which comprises the following steps:

plating the plating elements on the surfaces of the diamond particles to form surface plating layers to obtain plated diamond particles;

The surface of the diamond particles is treated before plating, so that the surface of the diamond is clean and pollution-free. Meanwhile, in order to improve the bonding force between the plated carbide and the surface of the diamond, the diamond is subjected to plating processes such as surface sensitization, activation and coarsening so as to realize the tight bonding of the carbide on the surface. In the embodiment, the particle size of the diamond particles is 50-300 meshes, different particle sizes are selected according to different products, and the requirements of different thicknesses and different heat conductivity coefficients can be met. In a further embodiment, the surface treatment of the diamond particles comprises: one or more of acid washing, alkali washing, boiling, surface cleaning and screening, wherein the treatment time of each procedure is 5-30 min. Compared with the traditional process, the surface treatment method provided by the application can be flexibly adjusted under actual use working conditions to meet the requirements of different products and improve the interface adsorbability and cleanliness of materials.

The method comprises the steps of carrying out surface sensitization, activation, coarsening and other treatments on the diamond, improving the plating quality and facilitating the reaction of a subsequent plating layer and diamond particles.

For example, the following steps are carried out: and screening the diamonds meeting the requirements. And screening and filtering the small-particle diamond by using a standard sieve to obtain diamond particles meeting the requirements, and carrying out a plating experiment.

The screened diamond particles were washed with acetone in an ultrasonic washer twice for 30min each time, then twice with alcohol for 15min each time, and finally with plasma water. This was repeated three times, each for 15min, for the purpose of removing the impurity substances on the diamond surface. Meanwhile, the cleaned diamond particles are put into a drying oven for drying treatment for experiments.

Alkali and acid boiling are respectively adopted to process the diamond, and the boiling process mainly comprises the following steps: the original solution is boiled, then the diamond is poured in and heated, and the cleaned diamond is poured in when bubbles are formed, and timing is started. And (3) boiling 100g of the cleaned diamond particles with 10% NaOH, stirring in the boiled sodium hydroxide solution for 20min to remove oil stains on the surface of the diamond, and cleaning the diamond after alkali cleaning in the two steps. And then, cleaning and stirring the diamond subjected to alkali washing treatment by using 20% of HCl solution in a proportioning ratio, and finally, cleaning, drying and sealing the solution subjected to acid washing for a plating experiment. The main purpose of this process is to remove the impurity elements from the diamond surface and to activate the diamond surface.

Because the wettability between metal elements such as diamond, copper and the like is extremely poor, solid solution and carbide can not be formed, the metal elements and the copper are simply and mechanically combined, holes and gaps are easy to exist in an interface, the interface combination is weak due to the poor wettability of the metal interfaces such as diamond, copper and the like, the mean free path of a heat carrier on the interface is greatly reduced, and the heat sink with high heat conductivity coefficient is difficult to obtain. The diamond interface needs to be plated, so that the wettability, the bonding force and the heat dissipation capacity of the diamond particles and the metal powder are improved.

When the plating in the second step adopts vacuum micro-evaporation, the method specifically comprises the following steps: and (2) placing the diamond particles in a vacuum environment for heating, wherein the heating temperature is 900-1050 ℃, and the further optimization is 1000 ℃, and depositing the coating elements on the surface of the diamond by utilizing the sublimation phenomenon of the material at high temperature for 0.5-3 h, and the further optimization is 2 h. And ultrasonic auxiliary vibration is provided, the vibration frequency is 10-30kHz, and the amplitude is 2-10 mu m, so that the uniform plating on each surface of the particles in the micro-evaporation process is ensured.

If the salt bath is adopted for plating in the second step, the method specifically comprises the following steps: mixing diamond particles and coating elements, then covering a salt bath on the surface of the diamond particles, and performing high-temperature coating, wherein the coating temperature is 950-1050 ℃, the coating temperature is more preferably 1000 ℃, and the coating time is 5-30min, and the coating time is more preferably 15 min. The molar ratio of diamond to tungsten oxide is 15: 1-3: 1, and the preferable ratio is 8:1, and the high-temperature salt bath method provided by the embodiment realizes high-efficiency plating.

If magnetron sputtering is adopted for plating in the second step, the method specifically comprises the following steps: placing diamond particles in a magnetron sputtering device, and sputtering by using a magnetron sputtering target material, wherein the process is, for example, under the pressure of 0.01Pa-2Pa (further preferably the pressure of 1 Pa), the flowing Ar and N2 atmosphere is protected, the substrate is heated to 350 ℃, further preferably 280 ℃, and is kept for 30min, the current and the voltage of the magnetron sputtering process are respectively 0.1A-10A and 100V-1000V, and the visual and controllable coating can be realized by assisting in the monitoring of the ultrasonic vibration, the weight and the micro-vision process.

In order to keep the surface of the coated diamond particles in a stable state, the second step further comprises a carbonization treatment of the coated diamond particles: and (2) carrying out heat treatment on the coated diamond particles under inert gas to form carbides on the surfaces of the diamond particles, enhancing the bonding of the diamond particles and a coating interface and ensuring that the coating is not damaged in subsequent forming, wherein the process comprises the steps of protecting the coating under the atmosphere of 0.01Pa-0.1MPa, carrying out flowing Ar and N2, carrying out heat treatment at the temperature of 850-1100 ℃ and carrying out heat preservation for 20-180 min.

In further embodiments, the plating elements include, but are not limited to, W, Mo, Cr, Ti, Si, B, etc., and WCx, MoCx, TiC, SiC, B₄C, and the volume fraction of the plating element is 0.2-1%. And the surface plating includes: one or more of vacuum micro-evaporation method, magnetron sputtering method and salt bath method. By plating the nano-scale to micro-scale plating layer on the surface of the diamond particles, the problems of poor interface wettability, low bonding strength and the like of metal elements such as diamond, copper, aluminum and the like are solved, and the high heat-conducting property and the adjustable linear expansion coefficient of the diamond-based feed are ensured.

In a further embodiment, the metal particles in step three comprise: metal powder or alloy powder; wherein the metal powder is at least one selected from Cu or Al; the alloy powder is at least one selected from the group consisting of CuCr, AlTi, and CuTi (the mass fraction of the added Cr element is 0.1% to 3%, and more preferably 1.8%).

And (3) uniformly mixing the coated diamond particles obtained in the step (II) with metal particles to obtain a mixed material, and placing the mixed material into mixing equipment for mixing, wherein the mixing temperature is 150-240 ℃, the mixing time is more preferably 200 ℃, and the mixing time is 30-180 min, and the mixing time is more preferably 120 min. Gradually adding a binder into the mixing equipment according to a preset adding mode, wherein the binder comprises: one or more of polypropylene, polyethylene, paraffin, stearic acid or polyformaldehyde. The prepared feed is applied to the micro-channel heat sink.

In order to avoid oxidation of the plated diamond particles and the metal particles during mixing and granulating, protective gas needs to be introduced during mixing and granulating to form a protective atmosphere.

The concrete expression is as follows: uniformly mixing the plated diamond particles with Cu powder or CuCr alloy powder, heating a mixing device to a preset temperature, sequentially adding the mixed powder of the diamond particles and the Cu powder and paraffin-based binder, mixing for 1-5 hours under the protective atmosphere of Ar and N2, and granulating to obtain granular feed with the length of 3-10 mm.

In another embodiment, the coated diamond particles and Al powder or AlTi alloy powder are uniformly mixed in Ar, N2 inert atmosphere or H2 reducing atmosphere, the mixing device is heated to a preset temperature, the mixed powder of the diamond particles and the Al powder and POM-based binder are sequentially added, and the mixture is mixed in Ar, N2 protective atmosphere and then granulated to prepare the injection molding feed.

Example 2

The micro flow channel heat sink prepared by injection or/and welding process using the feedstock prepared by the preparation method of example 1, as shown in fig. 1, includes: the heat sink comprises a heat sink body 1, a heat sink body and a heat sink body, wherein the top of the heat sink body is provided with an accommodating part 2 from top to bottom, and the accommodating part is used for accommodating a bare chip 3; the bottom of the heat sink body 1 is provided with a plurality of horizontally arranged heat dissipation flow channels 4; as shown in fig. 2, the number and shape of the heat dissipation channels 4 are determined according to the heat dissipation requirement, and the heat dissipation channels are shaped as mutually independent cylinders, tubular with a certain radian, or mutually communicated Y-shaped holes. In other words, the bottom of the receiving portion is used as a boundary to divide the body into an upper part and a lower part, and the heat dissipation flow channel is located at the lower part.

For a heat sink body with a simple internal structure, the following preparation method is adopted in the embodiment: and placing a preset die on an injection molding machine, injecting the molten feed material into the die to form a blank by using the injection molding machine as a feed material, and performing densification and degreasing treatment on the blank to obtain a densified heat sink body.

In a further embodiment, the predetermined mold usage conditions are: the cylinder temperature is 150 to 230 ℃, more preferably 190 ℃, the nozzle temperature is 160 to 220 ℃, more preferably 200 ℃, the injection pressure is 50MPa to 200MPa, more preferably 150MPa, the mold temperature is 50 to 150 ℃, more preferably 100 ℃, and the dwell time is 3s to 15s, more preferably 10 s.

The densification treatment specifically includes: placing the blank after injection molding in a vacuum environment, heating at a low speed by a heating furnace to pyrolyze and volatilize the binder, and continuously introducing Ar and N₂And (4) heating under a protective atmosphere to densify the micro-channel structure.

In a further embodiment, the densified micro flow channel structure is placed in a hot isostatic pressing furnace for further densification, the hot isostatic pressing temperature being 500 ℃ to 950 ℃, and more preferably 800 ℃; the pressure is 500MPa to 1000MPa, and more preferably 800 MPa.

The degreasing environment is as follows: solvent degreasing for 5-24h, preferably 15h, heating the temperature to 500 ℃ at a rate of 0.1-0.5 min/DEG C, then heating the temperature to 600-1000 ℃ (preferably 800 ℃) for 1-5 min/DEG C, finally sintering and densifying, wherein the sintering temperature is 700-1200 ℃ (preferably 1000 ℃) and the holding time is 0.5h-3h (preferably 2 h), and obtaining the densified micro-channel structure. The embodiment adopts powder injection molding to manufacture the micro-channel heat sink, reduces working procedures, and can effectively improve the manufacturing efficiency and the cost.

Degreasing is to remove the binder from the injection feedstock, and thermal degreasing generally involves three stages, an initial stage, an intermediate stage, and a final stage. In the initial stage, when the degreasing temperature is heated to a certain temperature, the melting point of a certain binder is reached, the binder starts to melt, the temperature is continuously raised, so that the binder is decomposed to form gas, the gas on the surface of the blank material can directly enter the surrounding atmosphere, fine gaps are formed on the surface of the blank material, the liquid and gaseous binders in the blank material start to migrate to the surface of the blank material under the action of capillary force, and the generated gas substances can only be dissolved in the liquid binder and continuously increase after reaching saturation due to the fact that no gap channel penetrating from the interior of the blank material to the surface is formed, so that defects such as bubbles and cracks can be caused, and the defects cannot be healed in the subsequent sintering process and can be amplified. In the intermediate stage, due to the volatilization of the binder on the surface of the blank material and the migration of the internal gas to the surface of the blank material, a through gap is formed from the surface to the inside, and the formation of the through gap enables the liquid-phase binder and the decomposed gas to more easily migrate to the surface, thereby being more beneficial to the discharge of the binder. The initial stage mainly takes the migration of liquid-phase binder and gas as main components, and the formed gas mainly takes diffusion and osmotic mass transfer in the through voids, and the formed through voids also change the decomposition and volatilization rate of the liquid-phase binder. At the final stage, most of the binder is removed, but the degreasing temperature needs to be further increased to ensure complete removal of the binder. Another important reason is that after the binder is completely removed, the degreased parts contain a large number of gaps, so that the mechanical properties of the parts are poor, the parts can be damaged when being taken out of the degreasing furnace for next sintering, and the degreased parts can be pre-sintered by continuously increasing the temperature, so that soft bonding is formed among degreased particles and the degreased particles have enough strength for carrying treatment. Wherein the temperature rise rate of thermal degreasing is 0.1 min/DEG C, 1 min/DEG C after the temperature rises from 0.2 min/DEG C to 500 ℃, and the temperature rises to 600 ℃, 700 ℃, 900 ℃ and 1000 ℃ after the temperature rises to 1 min/DEG C.

The sintering specifically comprises the following steps: and placing the blank after injection molding in a degreasing solvent for degreasing, transferring the blank into a gas pressure sintering furnace under the condition of ensuring the carrying strength of the product, and realizing the densification of the product through the dual functions of temperature and gas pressure, wherein the gas pressure is 1-10MPa, and the heat preservation time is 1-3 h.

The purpose of the sintering process is to reduce the surface energy of the degreased part, and a grain boundary surface between crystal grains replaces a solid-gas interface between powder particles and air holes, so that the volume of the part is shrunk and compacted. Vacuum sintering and gas pressure sintering are adopted. Wherein, vacuum sintering: sintering at 2 min/deg.C and 3 min/deg.C, at 700 deg.C, 800 deg.C, 1000 deg.C and 1200 deg.C, and maintaining for 0.5h, 1h, 1.5h and 3h to obtain a densified micro-channel structure, as shown in FIG. 3. Thermal isostatic compaction under reduced pressure: if the vacuum sintered product is placed in a hot isostatic pressing furnace, the sintering temperature rise rate is 10 min/DEG C and 15 min/DEG C, the sintering temperature is 600 ℃, 700 ℃, 900 ℃, 1000 ℃, the heat preservation time is 1h and 2h, and the pressure is 500Mpa, 800Mpa and 1000 MPa. And (3) air pressure sintering: placing the blank after injection molding in a degreasing solvent for degreasing, transferring into a gas pressure sintering furnace at 5-15 deg.C/min under the condition of ensuring product handling strength, passing Ar and N₂And H₂One or more of the above components, the air pressure is 0.3-20MPa, and the heat preservation time is 1-3 h.

Example 3

In contrast, when the heat sink body was prepared in example 2, defects such as air holes, hollows, and cracks were easily generated during the injection molding, which were amplified during degreasing and sintering and could not be eliminated. The reason is analyzed: the vibration system was dynamically analyzed in conjunction with the flow impact characteristics of the powder microinjection molding filling process. A visual mould and a capillary rheometer are adopted to research the rheological characteristics of diamond/copper feeding in different ultrasonic loading modes and different ultrasonic processes (ultrasonic pressure, ultrasonic duration and dwell time), a measuring window is arranged laterally on a mould core, the temperature field change in the process is dynamically displayed by an infrared thermal imaging device, and the action mechanisms of ultrasonic 'frictional thermogenesis effect' and 'cavitation effect' and the like on plasticization are clarified by combining the micro-morphology analysis of a short-shot component. Through a plurality of researches of earlier experiments, parameters such as plasticizing temperature, injection pressure, mold temperature, pressure maintaining time and the like have great influence on the quality of injection molding parts.

Therefore, the present embodiment makes the following improvements: when the feed is injected into a die, high-performance injection and uniform filling of the feed are realized by the coupling effect of ultrasonic vibration and powder injection molding on filling, the vibration frequency is 20-40kHz, the amplitude is 2-5 mu m, and the plasticizing temperature, the injection pressure, the die temperature, the dwell time, the ultrasonic amplitude, the vibration frequency and the like are adjusted.

For example, the following steps are carried out: an example of the ultrasonic-assisted powder injection molding micro-channel heat sink mold system shown in fig. 4 comprises a fixed mold 5, a movable mold 6, an ultrasonic vibration device 7 and an amplitude transformer integrated core according to the powder injection molding requirement. Firstly, a lower moving die and a fixed die are clamped under the guidance of a driving and guiding mechanism of an injection molding machine, the injection molding machine injects molten feed into the die as feed through a sprue, and at the moment, an ultrasonic vibration device starts to work, and the action time and the pressure maintaining time are synchronous. After the ultrasound is finished, the movable mold and the fixed mold are driven by the injection molding machine to open the mold, and the mechanism is ejected out of the micro-channel heat sink.

Typical process parameters for injection molding of paraffin-based feed powders are shown in Table 1, using paraffin-based feed as an example, at a vibration frequency of 20-40kHz and an amplitude of 2-5 μm.

TABLE 1 Paraffin-based feed powder injection Molding Process parameter examples

Injection molding process parameters	Numerical value
		Temperature of the barrel	160℃
Nozzle temperature	170℃
		Temperature of the mold	60℃
Injection pressure	70MPa
		Clamping force of mold	110KN
Rate of injection	45cm³/s
		Dwell time	6s

The paraffin-based mixing typical process comprises the following steps: firstly adding mixed powder weighed in advance, heating to 170 ℃, keeping the temperature for 10min, starting a double-planetary rotor, rotating at the speed of 30r/min to enable the whole powder to be uniformly heated, then rotating at the rotating speed of 50r/min, gradually adding PP and PE into a charging barrel, adding PW and SA after mixing for 30min, continuing mixing for 30min, then cooling and taking out the mixed feed, extruding for multiple times on an extruder to obtain cylindrical feed particles with the length of 2-3mm shown in figure 5, and setting the temperatures at a feed inlet, an intermediate heating zone and a discharge outlet to 165 ℃, 170 ℃ and 160 ℃ respectively during extrusion granulation.

Example 4

For an internal micro-channel with a complex structure in the heat sink or which cannot be realized by adopting an injection molding mold core design, the embodiment adopts the following molding method, the heat sink body is divided according to the shape of a heat dissipation channel as required, and is divided into a plurality of areas, and each area is provided with a corresponding sub-mold; and preparing a plurality of sub heat sink bodies in each sub mold respectively, and assembling the sub heat sink bodies according to a preset typesetting in a welding and packaging mode. And the diffusion welding mode is adopted for welding and packaging, other media are not introduced, and the welding strength and the heat dissipation performance are ensured, as shown in fig. 6.

The method for preparing the sub-heatsink body is the same as that in embodiment 3, and is not described in detail in this embodiment. The conventional diffusion bonding needs to be heated in a heating furnace integrally, the temperature is high, the time is long, the surface of the diamond can be graphitized in a vacuum environment of 700-1400 ℃, the heat dissipation performance is seriously deteriorated, and the method becomes an effective means through pulse current assistance. The reliable connection of the flow channel heat sink directly determines the reliability of the core chip and even the whole electronic equipment, solder is not required to be added in the diffusion connection, the welding temperature is lower than the melting point of the material, and the integrated precise forming of the micro-flow channel heat sink body in the embodiment can be realized.

The solder packaging used the following method: referring to fig. 7, after the densified partitioned micro flow channel structure (i.e., the sub-heat sink body prepared in this embodiment) is assembled, the assembled partitioned micro flow channel structure is placed in a vacuum diffusion welding furnace 9, the temperature is raised to a diffusion welding temperature of 500-900 ℃, the partitioned micro flow channel structure is pressurized, the pressure is 3-15MPa, and the temperature is maintained for 30-120 min, so that the welding and packaging are realized.

Alternatively, as in fig. 8, the solder package uses the following method: after a densified partitioned micro-channel structure (namely the sub-heat sink body prepared in the embodiment) is assembled by adopting a preset clamp 8, the positive electrode and the negative electrode (heating electrode 10) of a high-frequency power supply are respectively connected to two ends of the assembly structure, the power supply is powered up, the current is 3000A-10000A, the high-frequency power supply is heated by self resistance of equipment, diffusion welding pressure is applied by the clamp, the pressure is 3-15MPa, the heat is preserved for 10min-30min, and the integral welding and packaging are realized.

Example 5

The obtained micro flow channel heat sink was prepared based on examples 2 to 4. Comprises the following components: coating diamond particles, metal particles and a binder; wherein the plating diamond particles comprise diamond particles, and a plating layer is plated on the surfaces of the diamond particles.

In further embodiments, the diamond and metal materials provided by the embodiments of the present application include, but are not limited to, the following:

diamond particles, particle size: 80 meshes, 100 meshes, 120 meshes, 140 meshes, 170 meshes, 200 meshes and 230 meshes. The plating elements, W, Mo, Cr, Ti, Si, B, etc., are obtained by controlling the process parameters to obtain different mass fractions of the plating elements.

For example, the following steps are carried out: placing 120-mesh diamond particles and Mo powder into a ball mill according to a molar ratio of 9:1, ball milling at a ball milling rotating speed of 210 revolutions, ball milling for 1h in a forward and reverse rotation mode, taking out the powder, placing the powder into self-grinding ultrasonic-assisted micro-evaporation equipment, designing micro-evaporation temperature, 900 ℃, 925 ℃, 950 ℃, 975 ℃, 1000 ℃ and the like, and raising the speed to 2 ℃, 5 ℃ and 10 ℃ min, micro-evaporation time to 0.5h, 1h, 1.5h, 2h and 3h, vibration frequency to 10kHz, 15kHz, 20kHz, 25kHz and 30kHz, amplitude to 2 μm, 5 μm, 8 μm and 10 μm, and obtaining a plating surface meeting performance as shown in FIG. 9.

Alternatively, 100 mesh diamond particles are mixed with WO₃The powder is placed into a high-energy ball mill according to the molar ratio of 10:1, 8:1 and 6: 1. Simultaneously, KCl, NaCl and CaCl in the molar ratio of 3:2:1, 2:2:1, 1:1:1 are added₂And putting the powder into a high-energy ball mill together, ball-milling at the ball-milling rotating speed of 300 revolutions per minute, ball-milling for 1h and 1.5h respectively in a forward and reverse rotation mode, taking out the powder mixed with the salt, putting the powder into self-grinding ultrasonic-assisted micro-evaporation equipment, designing micro-evaporation temperature to be 950 ℃, 1000 ℃ and 1050 ℃, raising the speed to be 2 ℃/min, 5 ℃/min and 10 ℃/min, and micro-evaporation time to be 10min, 15min, 20min, 25min and 30min, and obtaining a plating surface meeting the performance as shown in figure 10.

Or, 100-mesh diamond particles are placed in a magnetron sputtering carrying vessel with a vibrator, a high-purity W target material is adopted, and the pressure of a magnetron sputtering cavity is as follows: 0.01Pa, 0.1Pa and 1Pa, heating the substrate to 200 ℃, 250 ℃, 300 ℃ and 350 ℃, keeping the temperature for 20min, 30min and 40min, and controlling the magnetron sputtering current: 0.1A, 0.5A, 1A, 5A, magnetron sputtering voltage 300V, 500V, 800V, vibration frequency 10kHz, 15kHz, 20kHz, 25kHz, 30kHz, amplitude 2 μm, 5 μm, 8 μm, 10 μm, all in flowing Ar atmosphere, as shown in FIG. 11, the plated surface satisfying the performance was obtained.

After the surfaces of the diamond particles are plated, the combination of the plating layer and the surfaces of the diamond particles is weakly combined, the diamond particles and the surface plating layer can react to form carbide through heat treatment, the interface combination is enhanced, and the plating layer is prevented from being damaged during subsequent mixing and granulation.

In another embodiment, the coated diamond particles are placed in a crucible and further placed in a heat treatment furnace with a rate of temperature increase: 2 ℃/min, 5 ℃/min, 10 ℃/min, heat treatment temperature: the heat treatment of the plated diamond particles can be completed by holding the temperature at 900 deg.C, 1000 deg.C, 1100 deg.C, 1200 deg.C for 40min, 80min, 160min, as shown in FIG. 12.

In order to manufacture the micro-channel heat sink, the diamond-based feed and the binder are required to be mixed and granulated, and diamond particles with different particle sizes are selected to be mixed in proportion, so that the problem of bridge arch during sintering is avoided. After the proportion of diamond particles and copper is determined, mixed powder of diamond and metal is obtained by mixing, the mixed powder and a base binder are fed on a mixing granulator according to the volume ratio, and in order to prevent the oxidation of copper powder during mixing, the whole process adopts vacuum or Ar atmosphere protection.

For example, the following steps are carried out: 55%, 57% and 60% of paraffin wax in volume fraction of diamond, Cu, Al, CuCr, AlSi and the like are adopted as metal powder, and the weight volume fraction of elements added in the alloy powder is as follows: 0.3wt.%, 0.52wt.%, 0.75wt.%, 1 wt.%. A paraffin-based binder volume ratio of PP to PE to PW to SA =70:15:10:5, 30:35:30:5, 20:30:45: 5. The volume ratio of the POM binder is POM to PE to PW to EVA to SA =70 to 15 to 10 to 5, 75 to 15 to 5, and 60 to 15 to 20 to 5.

In summary, the micro-channel heat sink and the preparation method of the micro-channel heat sink of the present embodiment can be used for manufacturing chip heat sinks, but are not limited to chips for military and civilian electronic devices such as 5G base stations, unmanned systems, LEDs, military radars, communication devices, and the like.

Claims

1. A preparation method of feed is characterized by comprising the following steps:

step one, carrying out surface treatment on diamond particles;

2. A method for preparing a feedstock as defined in claim 1 wherein the surface treatment in step one comprises: one or more working procedures of acid washing, alkali washing, boiling, surface cleaning and screening, wherein the treatment time of each working procedure is 5-30 min.

3. A method for preparing a feed stock as set forth in claim 1, wherein the surface plating in the second step comprises: one or more of a vacuum micro-evaporation method, a magnetron sputtering method and a salt bath method;

the second step further comprises: and (4) performing heat treatment on the coated diamond particles.

4. A process for preparing a feedstock according to claim 1,

the adhesive comprises: one or more of polypropylene, polyethylene, paraffin, stearic acid or polyformaldehyde.

5. The feed prepared by the method for preparing a feed according to any one of claims 1 to 4 is used for chip heat dissipation.

6. A micro flow channel heat sink, which is prepared by using the feed material of any one of claims 1 to 4 and adopting the injection or/and welding process;

the microchannel heat sink comprises: the heat sink body is provided with at least one accommodating part from top to bottom; the bottom of the heat sink body is provided with a plurality of horizontally arranged heat dissipation runners; the number and the shape of the heat dissipation flow channels are determined according to the heat dissipation requirement.

7. The micro flow channel heat sink of claim 6 comprising the following components: coating diamond particles, metal particles and a binder;

8. The method of making the micro flow channel heat sink of claim 6, comprising at least the steps of: and placing a preset die on an injection molding machine, injecting the molten feed into the die by the injection molding machine to form a blank, and sequentially performing densification, degreasing and sintering treatment on the blank to obtain the densified heat sink body.

9. The method of preparing a micro fluidic channel heat sink of claim 7, further comprising:

when the feedstock is injected into the mold, an ultrasonic vibration device is used to act on the mold to promote flow of the molten feedstock.

10. The method of making the micro flow channel heat sink of claim 6, comprising at least the steps of:

and preparing a plurality of sub heat sink bodies in each sub mold respectively, and assembling the sub heat sink bodies according to a preset typesetting in a welding and packaging mode.