A preparation method of high-thermal-conductivity copper heat dissipation material injection molding

Abstract

The application provides a preparation method of high-thermal-conductivity copper heat dissipation material injection molding, and relates to the technical field of powder metallurgy. The method comprises the following steps: weighing electrolytic copper powder, and sequentially performing airflow breaking treatment and grinding treatment to obtain agglomerated and dispersed electrolytic copper powder; mixing the electrolytic copper powder, atomized copper powder and copper alloy powder to obtain raw material powder; performing high-temperature and high-speed closed kneading of the raw material powder and plastic-based binder to obtain high-purity feedstock; then performing injection molding of the high-purity feedstock to obtain a green part; then performing catalytic degreasing and heating degreasing on the green part to obtain a sample after thermal degreasing; and sequentially performing normal-pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere on the sample after thermal degreasing to obtain full-dense high-thermal-conductivity copper heat dissipation material. The application realizes the synergistic improvement of the comprehensive performance of copper material through multiple sintering densification mechanisms such as powder particle size matching, atmosphere protection kneading, liquid phase sintering effect, activation sintering effect and hot isostatic pressing sintering combined action.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of powder metallurgy, and particularly to a preparation method of injection forming of high-thermal-conductivity copper heat dissipation material. BACKGROUND

[0002] With the increase of shape complexity, the heat sink is designed to be more efficient in heat transfer, and the copper material has good electrical and thermal conductivity. The thermal conductivity of copper is about 401 W / (m·k), which is about 1.7 times that of pure aluminum, and the thermal expansion coefficient is also about 6×10 -6 / K lower than that of pure aluminum. Copper material not only integrates the characteristics of high thermal conductivity and low thermal expansion coefficient of thermal management materials, but also has good corrosion resistance, which to a large extent solves the problem of easy wear and tear and frequent maintenance of devices in high temperature and corrosive environment. Therefore, in certain circumstances, copper-based materials are often the first choice for thermal management materials.

[0003] Metal injection molding can provide a unique thermal management solution to dissipate heat from microelectronic devices. Metal injection molding allows necessary design freedom and provides a cost-effective method to manufacture a large number of heat sinks required for electronic devices. Traditional production methods include extrusion, casting and machining, etc.; among them, extrusion is a highly automated, low-cost, mass production process, but it itself limits the geometry of the fins. Extrusion or die casting processing can produce fins with high gap ratio, but the cost is high. Similarly, the performance of folded fin heat sinks is improved by two times compared with extruded fins, but the cost is also increased, and the material utilization rate is low in mechanical machining and other ways, and the close arrangement structure of needle fins also makes the processing difficult to some extent, and the low utilization rate of materials also makes the cost of large-scale manufacturing high.

[0004] And Chinese patent CN111996405A discloses a method for preparing high-strength and high-conductivity copper alloy by metal injection molding. The method needs to use internal oxidation method to prepare Al2O3 dispersed copper powder. However, although Al2O3 dispersed copper powder can improve the thermal conductivity to some extent, the thermal conductivity is not greatly improved, the electrical conductivity is also not high, and the density is also the same.

[0005] Chinese patent CN102554229A discloses a method for preparing gradient structure copper heat dissipation fin by injection molding. The method needs to use two different copper powder gradations, and the difficulty of two-cavity injection in the injection molding process is very large; and sintering and pressure processing can densify the prepared heat dissipation fin, but the fin of the heat dissipation fin is a porous structure material with a relative density of 50-96%, and the electrical conductivity is poor, and the thermal conductivity performance of each part is not uniform.

[0006] Chinese patent CN117926153A discloses a heat treatment method for preparing high-strength and high-conductivity copper alloy, which needs to use directional solidification technology to solidify alloy plates with different texture directions layer by layer to form a whole alloy material stacked according to the soft and hard orientation rules, and after rolling, a high-strength and high-conductivity copper alloy is obtained through a cyclic heat treatment method; wherein the shape and method of the prepared material are limited, so it is known that complex-shaped copper parts cannot be prepared, and the stacking according to the soft and hard orientation rules makes the prepared alloy material have improved tensile strength, but the electrical conductivity cannot reach 90% IACS.

[0007] Chinese patent CN101966587A discloses a method for preparing high-performance heat pipe copper powder, which needs to melt high-purity electrolytic copper plates first, then add copper oxide powder, then sprinkle amorphous carbon powder into the crucible during the atomization process, then perform whole atomization of the leakage package to obtain powder, and finally dry and reduce, crush and sieve to obtain pure copper powder; although the pure copper powder can be used for the preparation of high-performance heat pipes, the preparation process of the pure copper powder is complex and difficult to operate, and the process cost is high and the efficiency is low during the preparation of high-performance heat pipes, which is not conducive to industrial application. SUMMARY

[0008] To solve the technical problems in the prior art that the material utilization rate of the heat sink is low, the structure is complex and difficult to prepare, the production cost is high, if alloy elements are added to improve the thermal conductivity and electrical conductivity, the performance of the two cannot be improved simultaneously, complex-shaped copper parts cannot be prepared, and the operation is difficult; the present application provides a preparation method for injection molding of high-thermal-conductivity copper heat dissipation material which can solve the above problems. The technical solution is as follows:

[0009] A preparation method for injection molding of high-thermal-conductivity copper heat dissipation material, the preparation method for injection molding of high-thermal-conductivity copper heat dissipation material comprises the following steps:

[0010] S1, electrolytic copper powder agglomeration and dispersion treatment: weigh electrolytic copper powder, and sequentially perform airflow crushing treatment and grinding treatment to obtain agglomerated and dispersed electrolytic copper powder;

[0011] S2, raw powder preparation: uniformly stir and mix the agglomerated and dispersed electrolytic copper powder, atomized copper powder and copper alloy powder to prepare raw powder;

[0012] S3, injection molding: high-temperature and high-speed densification of the raw powder and plastic-based binder to obtain high-purity feedstock; injection molding of the high-purity feedstock to obtain a green part with no defects, no deformation and uniform composition; then catalytic and thermal debinding of the green part to obtain a sample after thermal debinding;

[0013] S4, normal pressure sintering + hot isostatic sintering: the sample after S3 heat removal is sequentially subjected to normal pressure sintering in a hydrogen atmosphere and hot isostatic sintering in a nitrogen atmosphere, to obtain a full-dense high-thermal-conductivity copper heat dissipation material.

[0014] Optionally, in the S1 gas flow breaking process, the classification wheel rotation speed is 9000-12000 r / min; in the grinding process, 0.5% anhydrous ethanol and 1-1.5% stearic acid are added, and the electrolytic copper powder is ground at a pressure of 400-800 Kpa, and the feeding rate is 30-60 g / min.

[0015] Optionally, the average particle size of the agglomerated and dispersed electrolytic copper powder in S1 is 15-25 μm.

[0016] Optionally, in the S2 raw material powder, the mass fraction of the electrolytic copper powder is 20-40%, the mass fraction of the atomized powder is 70-90%, and the mass fraction of the copper-nickel alloy powder is 1-2%.

[0017] Optionally, the particle size of the electrolytic copper powder in S2 is less than or equal to 600 mesh, and D50 is 15-20 µm; the particle size of the atomized copper powder is 200-400 mesh, and D50 is 25-30 µm; the copper alloy powder is a copper-nickel alloy, in which the mass fraction of nickel is 60%, the mass fraction of copper is 33%, and the mass fraction of iron is 7%.

[0018] Optionally, in the S3 plastic-based binder, the mass fraction of polyformaldehyde is 75-85%, the mass fraction of polyethylene is 8-10%, the mass fraction of polypropylene is 4-6%, the mass fraction of ethylene-vinyl acetate copolymer is 4-6%, and the mass fraction of stearic acid is 4-6%; argon is selected as the protective atmosphere for the banburying atmosphere.

[0019] Optionally, in the S3 injection process, the injection temperature is 180-190℃, the injection pressure is 90-120 bar, the injection speed is 40-80 mm / s, and the mold temperature is 110-130℃; the main component of the binder removed by catalytic debinding is polyformaldehyde; in the thermal debinding, the heating rate is 1℃ / min from room temperature to 500℃, and the sample is kept at 200℃, 350℃, and 500℃ for 30 min, respectively.

[0020] Optionally, the debinding rate of the sample after S3 heat removal is 7.5-9.0%, and the density is 5.20-5.80 g / cm 3 .

[0021] Optionally, in the S4 normal pressure sintering step, the flow rate of the hydrogen introduced is ≥2 m 3 / min, the sintering temperature is 1060-1075℃, and the holding time is 4-6 h; in the hot isostatic sintering, the sample is kept at a temperature of 900-950℃ in a nitrogen atmosphere for 1-3 h.

[0022] Optionally, the density of the S4 full-density high-thermal-conductivity copper heat dissipation material is 99.5-99.9%, the tensile strength is 185-210 MPa, the tensile strain at break is 40.5-48.2%, the thermal conductivity is 360-376 W / (m*K), and the electrical conductivity is 82.5-90.8% IACS.

[0023] Compared with the prior art, the technical scheme has at least the following beneficial effects:

[0024] The preparation method of the high-thermal-conductivity copper heat dissipation material injection molding provided by the above scheme can solve the technical problems of low utilization rate of machining materials, complex structure, difficult preparation, high production cost, and the like of the heat sink in the prior art.

[0025] The preparation method of the present application prevents the high activity and easy oxidation characteristics of copper, realizes the sintering activation of electrolytic copper powder, the liquid phase sintering of low-melting copper-nickel powder, high shape retention of the plastic-based system sample, high debinding rate of the green body, and adopts hydrogen atmosphere sintering, hot isostatic pressing sintering, and other mechanisms to promote sintering densification.

[0026] The present application can greatly disperse the powder agglomeration by agglomerating and dispersing the electrolytic copper powder, thereby improving the tap density and making it easier to be coated by the binder, and increasing the powder loading capacity.

[0027] The present application can make the fine copper powder uniformly fill and distribute between the coarse copper powder by preparing raw material powder, maximize the combination with the binder by particle size matching, reduce the spacing between particles, reduce the sintering resistance under certain sintering activation energy, effectively improve the sintering efficiency, and reduce the sintering temperature by adding low-melting-point copper-nickel powder.

[0028] The present application can integrally form complex structure parts by injection molding, and the material utilization rate is as high as 98%, solving the problems of low utilization rate of machining materials, complex structure, difficult preparation, and high production cost of the heat sink, and providing a new idea for the preparation of heat sink devices with high material cost and complex structure.

[0029] The present application can fully grow the crystal grains by normal pressure sintering + hot isostatic pressing sintering, and the crystal grains are tightly combined, the sintered part is fully dense, thereby obtaining excellent comprehensive performance, high thermal and electrical conductivity, and good tensile performance, meeting the use requirements of the heat sink.

[0030] The prepared copper heat dissipation material has a density of more than 99%, a thermal conductivity of more than or equal to 365 W / (m*K), and an electrical conductivity of 90.5% IACS, and has excellent thermal conductivity and electrical conductivity, and the copper sample has a tensile strain of 45.78% and a tensile strength of 164.43 MPa, and has good ductility and tensile strength and is not prone to fracture, and can meet the performance requirements of high-thermal-conductivity complex-structure copper heat dissipation devices.

[0031] In summary, the method of the present application realizes the preparation of integrated acicular heat dissipation material through various sintering densification mechanisms such as powder particle size matching, atmosphere protection mixing, liquid phase sintering, activation sintering, and hot isostatic pressing sintering, which synergistically improves the thermal conductivity, electrical conductivity, and strength plasticity of the copper heat dissipation material. The method is simple, easy to operate, green, low in cost, short in process, and high in efficiency, and can meet the preparation of high-thermal-conductivity large-size complex-structure copper heat dissipation material, and is conducive to industrial large-scale production and promotion. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 is a microstructure diagram of a copper heat dissipation material prepared by a high-thermal-conductivity copper heat dissipation material injection molding preparation method of embodiment 1 of the present application;

[0034] Figure 2 is a microstructure diagram of a copper heat dissipation material prepared by a high-thermal-conductivity copper heat dissipation material injection molding preparation method of embodiment 2 of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the present application will be described below with reference to the drawings.

[0036] In the embodiments of the present application, the words "example", "for example" and the like are used to represent an example, illustration or description. Any embodiment or design scheme described as "example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the word "example" is intended to present the concept in a specific manner. In addition, in the embodiments of the present application, the meaning expressed by "and / or" can be both, or can be one of the two.

[0037] In the embodiments of the present application, "image" and "picture" can be used interchangeably at times. It should be pointed out that when the distinction is not emphasized, the meanings expressed are consistent.

[0038] In the embodiments of the present application, sometimes the subscript such as W1 may be written in the form of non-subscript such as W1, and the meanings expressed thereby are consistent when the difference is not emphasized.

[0039] To make the technical problems, technical solutions and advantages to be solved by the present application more clear, the following will be described in detail with reference to the drawings and specific embodiments.

[0040] A preparation method of high-thermal-conductivity copper heat dissipation material injection molding, the preparation method of high-thermal-conductivity copper heat dissipation material injection molding comprises the following steps:

[0041] S1, electrolytic copper powder agglomeration and dispersion treatment: electrolytic copper powder is weighed, and then airflow breaking treatment and grinding treatment are sequentially performed to obtain agglomerated and dispersed electrolytic copper powder;

[0042] S2, raw material powder preparation: the agglomerated and dispersed electrolytic copper powder, atomized copper powder and copper alloy powder prepared in S1 are uniformly stirred and mixed to prepare raw material powder;

[0043] S3, injection molding: the raw material powder prepared in S2 is subjected to high-temperature and high-speed compounding with a plastic-based binder to obtain high-purity feedstock; then a defect-free, non-deformed and composition-uniform green part is obtained through injection molding of the high-purity feedstock; and then the green part is subjected to catalytic degreasing and heating degreasing to obtain a sample after thermal degreasing;

[0044] S4, normal pressure sintering + hot isostatic pressing sintering: the sample after thermal degreasing prepared in S3 is sequentially subjected to normal pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere to obtain full-dense high-thermal-conductivity copper heat dissipation material.

[0045] Particularly, in the airflow breaking treatment process in S1, the rotational speed of the classification wheel is 9000-12000 r / min; in the grinding treatment process, 0.5% of anhydrous ethanol and 1-1.5% of stearic acid are added, and the electrolytic copper powder is ground at a pressure of 400-800 Kpa and a feeding rate of 30-60 g / min.

[0046] Particularly, the average particle size of the agglomerated and dispersed electrolytic copper powder in S1 is 15-20 µm.

[0047] Particularly, in the raw material powder prepared in S2, the mass fraction of the electrolytic copper powder is 20-40%, the mass fraction of the atomized powder is 70-90%, and the mass fraction of the copper-nickel alloy powder is 1-2%.

[0048] Particularly, the particle size of the electrolytic copper powder in S2 is less than or equal to 600 mesh, and D50 is 15-20 µm; the particle size of the atomized copper powder is 200-400 mesh, and D50 is 25-30 µm; and the copper alloy powder is a copper-nickel alloy, in which the mass fraction of nickel is 60%, the mass fraction of copper is 33%, and the mass fraction of iron is 7%.

[0049] In particular, the mass fraction of polyformaldehyde in the plastic-based binder in S3 is 75-85%, the mass fraction of polyethylene is 8-10%, the mass fraction of polypropylene is 4-6%, the mass fraction of ethylene-vinyl acetate copolymer is 4-6%, and the mass fraction of stearic acid is 4-6%; argon is selected as the protective atmosphere during compounding.

[0050] In particular, during the injection process of S3, the injection temperature is 180-190℃, the injection pressure is 90-120bar, the injection speed is 40-80mm / s, and the mold temperature is 110-130℃; the main component of the binder removed by catalytic debinding is polyformaldehyde; during thermal debinding, the sample is heated at a heating rate of 1℃ / min from room temperature to 500℃, and is kept at 200℃, 350℃ and 500℃ for 30min, respectively.

[0051] In particular, the debinding rate of the sample after thermal debinding in S3 is 7.5-9.0%, and the density is 5.20-5.80g / cm 3 .

[0052] In particular, in the atmospheric pressure sintering step of S4, the flow rate of the hydrogen gas introduced is ≥2m 3 / min, the sintering temperature is 1060-1075℃, and the holding time is 4-6h; during hot isostatic pressing sintering, the sample is kept at a temperature of 900-950℃ in a nitrogen atmosphere for 1-3h.

[0053] In particular, the full-density high-thermal-conductivity copper heat dissipation material of S4 has a density of 99.5-99.9%, a tensile strength of 185-210MPa, a tensile strain at break of 40.5-48.2%, a thermal conductivity of 360-376 W / (m·K), and an electrical conductivity of 82.5-90.8%IACS.

[0054] Example 1

[0055] A preparation method of a high-thermal-conductivity copper heat dissipation material injection molded, the preparation method of the high-thermal-conductivity copper heat dissipation material injection molded comprising the following steps:

[0056] S1, agglomeration and dispersion treatment of electrolytic copper powder: 3000g of 600-mesh electrolytic copper powder is weighed, and during the airflow crushing process, the classification wheel rotates at 10000r / min; after 2h of airflow crushing treatment, the average particle size of the electrolytic copper powder is 18.20μm; then 0.5% of anhydrous ethanol and 1.0% of stearic acid are added, and the electrolytic copper powder is ground under a grinding pressure of 600Kpa, with a feeding rate of 40g / min, to obtain agglomerated and dispersed electrolytic copper powder with an average particle size of 17.50μm;

[0057] S2, raw material powder preparation: the S1 agglomerated and dispersed electrolytic copper powder, atomized copper powder, copper-nickel alloy powder are mixed uniformly in a mixer at room temperature according to 28:70:2 to prepare the raw material powder; wherein the particle size of the electrolytic copper powder is less than or equal to 600 mesh, and the D50 is 17.50 µm; the particle size of the atomized copper powder is 325 mesh, and the D50 is 26.80 µm; the mass fraction of nickel in the copper-nickel alloy powder is 60%, the mass fraction of copper is 33%, and the mass fraction of iron is 7%;

[0058] S3, injection molding: the S2 raw material powder and the plastic-based binder (polyformaldehyde 85 wt.%, polyethylene 5 wt.%, polypropylene 4 wt.%, ethylene-vinyl acetate copolymer 3 wt.%, stearic acid 3 wt.%) are mixed at a volume ratio of 58:42 in a 185℃, 30r / min mixer for 60min, and argon is selected as the protective atmosphere, to obtain high-purity feedstock; then the high-purity feedstock is used to injection molding by using an injection molding machine and a matching mold to obtain a defect-free, non-deformed, and composition-uniform heat sink green part; then the heat sink green part is subjected to catalytic debinding and heating debinding to obtain a sample after thermal debinding; during the injection process, the injection temperature is 185℃, the injection pressure is 100bar, the injection speed is 60mm / s, and the mold temperature is 120℃; the main component of the binder removed by catalytic debinding is polyformaldehyde; during thermal debinding, the sample is heated at a heating rate of 1℃ / min from room temperature to 500℃, and is kept at 200℃, 350℃, and 500℃ for 30min, respectively; the debinding rate of the sample after thermal debinding is 7.8%, and the density is 5.54gcm 3 ;

[0059] S4, normal pressure sintering + hot isostatic pressing sintering: the S3 sample after thermal debinding is sequentially subjected to normal pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere; in the normal pressure sintering step, the flow rate of the hydrogen gas is 2m 3 / min, the temperature is raised to 500℃ at a rate of 1℃ / min, and then raised to 1070℃ at a rate of 2℃ / min after 500℃, and then kept at 1070℃ for 150min; during the hot isostatic pressing sintering, the hot isostatic pressing furnace is pressurized for re-sintering, the temperature is raised to 900℃ at a rate of 5℃ / min, sintered at 100MPa for 90min, and then kept at 100MPa for 30min, and then cooled at a rate of 2.3℃ / min to obtain a fully dense high-thermal-conductivity copper heat sink material.

[0060] As shown in Figure 1 , the fully dense high-thermal-conductivity copper heat sink material prepared in the embodiment has a needle-like close-packed columnar shape and an integrated substrate, the density is 99.5%, the tensile strength is 192MPa, the tensile strain at break is 40.5%, the thermal conductivity is 362W / (m·K), and the electrical conductivity is 82.5%IACS.

[0061] Comparative Example 1 is disclosed in Chinese patent CN111996405A, which discloses a method for preparing high-strength and high-conductivity copper alloy by metal injection molding. The method needs to use internal oxidation method to prepare Al2O3 dispersed copper powder. The advantages of metal injection molding method are exerted, which can prepare parts with complex shape, and can also improve the problem of sintering densification of Al2O3 dispersed copper powder, and effectively improve the thermal conductivity and electrical conductivity.

[0062] As can be seen from Comparative Example 1 and Comparative Example 1, the addition of Al2O3 plays a role in dispersing and strengthening copper, which greatly improves the yield strength of the material, but cannot maximize the improvement of thermal conductivity and electrical conductivity, and the dispersion affects the excellent ductility of copper. The thermal conductivity is not high after the improvement, the electrical conductivity is also not high, and the density is also the same. The present application maximizes the combination of powder particles and binder through the grading of coarse and fine copper powder, and the sintering efficiency is also effectively improved. The addition of low-melting-point copper-nickel powder also reduces the sintering temperature. Liquid phase sintering is used to promote sintering densification. Through normal pressure + hot isostatic pressing sintering, full densification is achieved, and the excellent thermal conductivity and electrical conductivity of copper are maximized.

[0063] Example 2

[0064] A preparation method of high-thermal-conductivity copper heat dissipation material injection molding, the preparation method of high-thermal-conductivity copper heat dissipation material injection molding comprises the following steps:

[0065] S1, electrolytic copper powder agglomeration and dispersion treatment: 4000g of 600 mesh electrolytic copper powder is weighed, and during the airflow crushing treatment, the classification wheel rotating speed is 12000r / min. After 3h of airflow crushing treatment, the average particle size of the electrolytic copper powder is 15.5μm. Then 0.5% of anhydrous ethanol and 1.5% of stearic acid are added, and the electrolytic copper powder is ground under a grinding pressure of 800Kpa. The feeding rate is 50g / min, and the agglomerated and dispersed electrolytic copper powder with an average particle size of 15.20μm is obtained.

[0066] S2, raw material powder preparation: the agglomerated and dispersed electrolytic copper powder, atomized copper powder and copper-nickel alloy powder prepared in S1 are uniformly stirred and mixed in a mixer at room temperature according to a ratio of 28:70:2 to prepare a raw material powder. The particle size of the electrolytic copper powder is less than or equal to 600 mesh, and the D50 is 15.20μm. The particle size of the atomized copper powder is 350 mesh, and the D50 is 25.3μm. The mass fraction of nickel in the copper-nickel alloy powder is 60%, the mass fraction of copper is 33%, and the mass fraction of iron is 7%.

[0067] S3, injection molding: the S2 raw material powder and the plastic-based binder (polyformaldehyde 85 wt.%, polyethylene 5 wt.%, polypropylene 4 wt.%, ethylene-vinyl acetate copolymer 3 wt.%, stearic acid 3 wt.%) are mixed at a volume ratio of 55:45 and subjected to internal mixing at 185℃ and 30r / min for 60min, and argon is selected as the protective atmosphere, to obtain high-purity feedstock; then the high-purity feedstock is used to obtain a defect-free, non-deformed, and composition-uniform heat sink green body by injection molding using an injection molding machine and a matching mold; then the heat sink green body is subjected to catalytic debinding and thermal debinding to obtain a sample after thermal debinding; during the injection process, the injection temperature is 190℃, the injection pressure is 120bar, the injection speed is 40mm / s, and the mold temperature is 130℃; the main component of the binder removed by catalytic debinding is polyformaldehyde; the thermal debinding is performed at a heating rate of 1℃ / min from room temperature to 500℃, and the sample is kept at 200℃, 350℃, and 500℃ for 30min, respectively; the debinding rate of the sample after thermal debinding is 8.8%, and the density is 5.70gcm 3 ;

[0068] S4, normal pressure sintering + hot isostatic pressing sintering: the sample after thermal debinding of S3 is sequentially subjected to normal pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere, wherein in the normal pressure sintering step, the flow rate of the hydrogen gas is 2m 3 / min, the temperature is raised to 500℃ at a rate of 1℃ / min, the temperature is raised to 1070℃ at a rate of 2℃ / min after 500℃, and then the sample is kept at 1070℃ for 150min; during the hot isostatic pressing sintering, the hot isostatic pressing furnace is pressurized and resintered, the temperature is raised to 900℃ at a rate of 5℃ / min, the sample is sintered at 100MPa for 90min, and then the sample is kept at 900℃ for 30min, and then the sample is cooled at a rate of 2.5℃ / min, to obtain a full-dense high-thermal-conductivity copper heat dissipation material.

[0069] As shown in Figure 2 , the full-dense high-thermal-conductivity copper heat dissipation material prepared in this embodiment has a shape of needle-shaped vertical columns arranged in close proximity and an integrated substrate, the density is 99.9%, the tensile strength is 209.8MPa, the tensile strain at break is 48.2%, the thermal conductivity is 376W / (m·K), and the electrical conductivity is 90.8%IACS.

[0070] Example 3

[0071] A preparation method of a high-thermal-conductivity copper heat dissipation material by injection molding, the preparation method of the high-thermal-conductivity copper heat dissipation material by injection molding comprising the following steps:

[0072] S1, electrolytic copper powder agglomeration and dispersion treatment: 200 g of electrolytic copper powder with a particle size of 600 mesh was subjected to air flow crushing treatment, the classification wheel rotation speed was 9000 r / min, the average particle size of the electrolytic copper powder was 19.8 pm after 3 h of air flow crushing treatment, then 0.5% anhydrous ethanol and 1.2% stearic acid were added, and the electrolytic copper powder was ground at a grinding pressure of 400 Kpa, the feeding rate was 30 g / min, and the agglomerated and dispersed electrolytic copper powder with an average particle size of 18.9 pm was obtained;

[0073] S2, raw material powder preparation: the agglomerated and dispersed electrolytic copper powder, atomized copper powder and copper-nickel alloy powder in S1 were mixed uniformly in a mixer at room temperature according to a ratio of 20:78:2 to prepare a raw material powder; wherein the particle size of the electrolytic copper powder was less than or equal to 700 mesh, and the D50 was 18.9 pm; the particle size of the atomized copper powder was 275 mesh, and the D50 was 30.0 pm; the mass fraction of nickel in the copper-nickel alloy powder was 60%, the mass fraction of copper was 33%, and the mass fraction of iron was 7%;

[0074] S3, injection molding: the raw material powder in S2 and the plastic-based binder (polyformaldehyde 75 wt.%, polyethylene 10 wt.%, polypropylene 5 wt.%, ethylene-vinyl acetate copolymer 5 wt.%, stearic acid 5 wt.%) were mixed at a volume ratio of 63:37 at 180°C and 30 r / min for 60 min in a mixer, argon was selected as the protective atmosphere, and high-purity feedstock was obtained; then, the high-purity feedstock was used to obtain a defect-free, non-deformed and composition-uniform heat sink green part by injection molding using an injection molding machine and a matching mold; then, the heat sink green part was subjected to catalytic debinding and heating debinding to obtain a sample after thermal debinding; during the injection process, the injection temperature was 180°C, the injection pressure was 90 bar, the injection speed was 45 mm / s, and the mold temperature was 115°C; the main component of the binder removed by catalytic debinding was polyformaldehyde; during thermal debinding from room temperature to 500°C, the sample was heated at a heating rate of 1°C / min, and was kept at 200°C, 350°C and 500°C for 30 min, respectively; the debinding rate of the sample after thermal debinding was 7.5%, and the density was 5.25 g / cm 3 ;

[0075] S4, normal pressure sintering + hot isostatic pressing sintering: the sample after thermal debinding in S3 was subjected to normal pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere, respectively; in the normal pressure sintering step, the flow rate of the hydrogen gas was 2 m 3The temperature is increased to 500℃ at a rate of 1℃ / min, and then increased to 1070℃ at a rate of 2℃ / min, followed by holding at that temperature for 150min. During hot isostatic pressing (HIP), the temperature is increased to 900℃ at a rate of 5℃ / min, and sintered at 100MPa pressure for 60min. Then, the temperature is held at that temperature and pressure for 30min. After sintering, the temperature is cooled down at a rate of 3.0℃ / min to obtain a fully dense, high thermal conductivity copper heat dissipation material.

[0076] The fully dense high thermal conductivity copper heat dissipation material prepared in this embodiment is in the shape of needle-like closely arranged pillars and an integrated substrate, with a density of 99.6%, a tensile strength of 195 MPa, a tensile strain at break of 42.1%, a thermal conductivity of 365 W / (m·K), and an electrical conductivity of 85.5% IACS.

[0077] Example 4

[0078] A method for preparing a high thermal conductivity copper heat dissipation material by injection molding, comprising the following steps:

[0079] S1. Electrolytic copper powder agglomeration and dispersion treatment: 2000g of 600-mesh electrolytic copper powder was weighed and subjected to air jet crushing treatment. The classifying wheel speed was 11000r / min. After air jet crushing treatment for 1.5h, the average particle size of the electrolytic copper powder was 18.9μm. Then, 0.5% anhydrous ethanol and 1.1% stearic acid were added. The electrolytic copper powder was ground under a grinding pressure of 450Kpa and a feed rate of 35g / min to obtain agglomerated and dispersed electrolytic copper powder with an average particle size of 18.2μm.

[0080] S2. Raw material powder preparation: The agglomerated and dispersed electrolytic copper powder, atomized copper powder, and copper-nickel alloy powder from S1 are mixed evenly in a mixer at room temperature in a mass ratio of 27:72:1 to prepare the raw material powder. The electrolytic copper powder has a particle size of less than or equal to 650 mesh and a D50 of 18.2 µm; the atomized copper powder has a particle size of 290 mesh and a D50 of 29.0 µm; the 600 mesh particle size has a D50 of 10-15 µm; the copper-nickel alloy powder contains 60% nickel, 33% copper, and 7% iron by mass.

[0081] S3, injection molding: the raw material powder of S2 and the plastic-based binder (polyformaldehyde 82wt.%, polyethylene 9wt.%, polypropylene 3wt.%, ethylene-vinyl acetate copolymer 3wt.%, stearic acid 4wt.%) are mixed at a volume ratio of 62:38 and mixed at 183℃ and 35r / min for 90min, argon is selected as the protective atmosphere, and high-purity feedstock is obtained; then the high-purity feedstock is used to injection molding machine and matched mold to obtain a defect-free, non-deformation, uniform composition of the radiator green part; then the radiator green part is subjected to catalytic debinding and heating debinding to obtain a sample after thermal debinding; during the injection process, the injection temperature is 183℃, the injection pressure is 95bar, the injection speed is 65mm / s, and the mold temperature is 125℃; the main component of the binder removed by catalytic debinding is polyformaldehyde; the thermal debinding is heated at a heating rate of 1℃ / min from room temperature to 500℃, and is kept at 200℃, 350℃ and 500℃ for 30min, respectively; the debinding rate of the sample after thermal debinding is 7.9%, and the density is 5.65 g / cm 3 ;

[0082] S4, normal pressure sintering + hot isostatic pressing sintering: the sample after thermal debinding of S3 is sequentially subjected to normal pressure sintering in hydrogen atmosphere and hot isostatic pressing sintering in nitrogen atmosphere, wherein in the normal pressure sintering step, the flow rate of the hydrogen gas is 2.5m 3 / min, the temperature is raised to 500℃ at a rate of 1℃ / min, the temperature is raised to 1070℃ at a rate of 1.5℃ / min after 500℃, and then the temperature is kept for 150min; during the hot isostatic pressing sintering, the hot isostatic pressing furnace is pressurized and resintered, the temperature is raised to 930℃ at a rate of 6℃ / min, and the sintering is carried out at 120MPa for 150min, and then the temperature is lowered at a rate of 3.5℃ / min after the sintering is completed, to obtain a full-dense high-thermal-conductivity copper heat sink material.

[0083] The full-dense high-thermal-conductivity copper heat sink material prepared in this embodiment has a shape of needle-shaped close-packed columns and an integrated substrate, a density of 99.8%, a tensile strength of 208MPa, a tensile strain at break of 46.2%, a thermal conductivity of 373W / (m·K), and an electrical conductivity of 90.2%IACS.

[0084] Example 5

[0085] A preparation method of a high-thermal-conductivity copper heat sink material injection molding, the preparation method of the high-thermal-conductivity copper heat sink material injection molding comprising the following steps:

[0086] S1, electrolytic copper powder agglomeration and dispersion treatment: 2500 g of electrolytic copper powder with a mesh size of 600 was subjected to air flow crushing treatment, the classification wheel rotation speed was 10500 r / min, the average particle size of the electrolytic copper powder was 17.20 pm after 3 h of air flow crushing treatment, then 0.5% anhydrous ethanol and 1.3% stearic acid were added, the electrolytic copper powder was ground at a grinding pressure of 550 Kpa, the feeding rate was 55 g / min, and the agglomerated and dispersed electrolytic copper powder with an average particle size of 15.80 pm was obtained;

[0087] S2, raw material powder preparation: the agglomerated and dispersed electrolytic copper powder, atomized copper powder and copper-nickel alloy powder of S1 were uniformly mixed in a mixer at room temperature according to a ratio of 28:70:2 to prepare a raw material powder; wherein the particle size of the electrolytic copper powder was less than or equal to 600 mesh, and the D50 was 15.80 pm; the particle size of the atomized copper powder was 310 mesh, and the D50 was 27.50 pm; the mass fraction of nickel in the copper-nickel alloy powder was 60%, the mass fraction of copper was 33%, and the mass fraction of iron was 7%;

[0088] S3, injection molding: the raw material powder of S2 and the plastic-based binder (polyformaldehyde 85 wt.%, polyethylene 5 wt.%, polypropylene 4 wt.%, ethylene-vinyl acetate copolymer 4 wt.%, stearic acid 2 wt.%) were mixed at a volume ratio of 55:44 at 188°C and 40 r / min for 80 min in an internal mixer, argon was selected as the protective atmosphere, and high-purity feedstock was obtained; then, a defect-free, deformation-free and composition-uniform heat sink green part was obtained by injection molding using an injection molding machine and a matching mold; then, the heat sink green part was subjected to catalytic debinding and heating debinding, and a sample after thermal debinding was obtained; during the injection process, the injection temperature was 188°C, the injection pressure was 95 bar, the injection speed was 70 mm / s, and the mold temperature was 118°C; the main component of the binder removed by catalytic debinding was polyformaldehyde; during thermal debinding from room temperature to 500°C, the sample was heated at a rate of 1°C / min, and was kept at 200°C, 350°C and 500°C for 30 min, respectively; the debinding rate of the sample after thermal debinding was 8.05%, and the density was 5.70 g / cm 3 ;

[0089] S4, atmospheric sintering + hot isostatic pressing sintering: the sample after thermal debinding of S3 was sequentially subjected to atmospheric sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere, wherein the flow rate of the hydrogen gas introduced in the atmospheric sintering step was 2.5 m 3 / min, and then heated to 450℃ at a rate of 1.5℃ / min, heated to 1075℃ at a rate of 2℃ / min after 450℃, and then kept for 120 min; during the HIP sintering, the pressure re-sintering was performed in the HIP furnace, heated to 940℃ at a rate of 4℃ / min, sintered for 90 min under a gas pressure of 90 MPa, and then cooled to room temperature at a rate of 2.8℃ / min after the sintering, to obtain the fully dense high-thermal-conductivity copper heat dissipation material.

[0090] The fully dense high-thermal-conductivity copper heat dissipation material prepared in this embodiment has a shape of needle-shaped close-packed columns and an integrated substrate, a density of 99.7%, a tensile strength of 201 MPa, a tensile strain at break of 44.2%, a thermal conductivity of 368 W / (m·K), and an electrical conductivity of 87.6% IACS.

[0091] Example 6

[0092] A preparation method of a high-thermal-conductivity copper heat dissipation material injection molding, the preparation method of the high-thermal-conductivity copper heat dissipation material injection molding comprising the following steps:

[0093] S1, agglomeration and dispersion treatment of electrolytic copper powder: 3000 g of electrolytic copper powder of 500 mesh was subjected to air flow crushing treatment, the classification wheel rotation speed was 9500 r / min, the average particle size of the electrolytic copper powder was 17.8 μm after 2.5 h of air flow crushing treatment, then 0.5% anhydrous ethanol and 1.3% stearic acid were added, and the electrolytic copper powder was ground under a grinding pressure of 550 Kpa, the feeding rate was 35 g / min, and the agglomerated and dispersed electrolytic copper powder with an average particle size of 17.0 μm was obtained;

[0094] S2, preparation of raw material powder: the agglomerated and dispersed electrolytic copper powder, the atomized copper powder, and the copper-nickel alloy powder in S1 were uniformly mixed in a mixer at room temperature according to a ratio of 25:74:1 to prepare the raw material powder; wherein the particle size of the electrolytic copper powder was less than or equal to 600 mesh, and the D50 was 17.8 μm; the particle size of the atomized copper powder was 350 mesh, and the D50 was 25.5 μm; the mass fraction of nickel in the copper-nickel alloy powder was 60%, the mass fraction of copper was 33%, and the mass fraction of iron was 7%;

[0095] S3, injection molding: the S2 raw material powder and the plastic-based binder (polyformaldehyde 85%, polyethylene 8 wt.%, polypropylene 3 wt.%, ethylene-vinyl acetate copolymer 2 wt.%, stearic acid 2 wt.%) are mixed at a volume ratio of 65:35 and milled at 182 DEG C and 35 r / min for 100 min, argon is selected as the protection atmosphere, and high-purity feedstock is obtained; then, the high-purity feedstock is used to injection molding by using an injection molding machine and a matched mold to obtain a defect-free, non-deformed, and composition-uniform heat sink green part; then, the heat sink green part is subjected to catalytic debinding and heating debinding, and a sample after thermal debinding is obtained; during the injection process, the injection temperature is 182 DEG C, the injection pressure is 115 bar, the injection speed is 55 mm / s, and the mold temperature is 115 DEG C; the main component of the binder removed by catalytic debinding is polyformaldehyde; during thermal debinding, the sample is heated at a heating rate of 1 DEG C / min from room temperature to 500 DEG C, and is kept at 200 DEG C, 350 DEG C, and 500 DEG C for 30 min, respectively; the debinding rate of the sample after thermal debinding is 8.3%, and the density is 5.72 g / cm 3 ;

[0096] S4, normal pressure sintering + hot isostatic pressing sintering: the sample after thermal debinding in S3 is sequentially subjected to normal pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere; in the normal pressure sintering step, the flow rate of the hydrogen is 2.2 m 3 / min, the temperature is raised to 650 DEG C at a rate of 1.2 DEG C / min, the temperature is raised to 1072 DEG C at a rate of 1.8 DEG C / min after 650 DEG C, and then the temperature is kept at 1072 DEG C for 180 min; during the hot isostatic pressing sintering, the hot isostatic pressing furnace is pressurized and resintered, the temperature is raised to 940 DEG C at a rate of 4.2 DEG C / min, and the sample is sintered at 115 MPa for 150 min, and then the sample is cooled in the furnace after sintering, and a full-dense high-thermal-conductivity copper heat dissipation material is obtained.

[0097] The full-dense high-thermal-conductivity copper heat dissipation material prepared in the embodiment has a shape of needle-shaped close-packed columns and an integrated substrate, the density is 99.6%, the tensile strength is 193.6 MPa, the tensile strain at break is 41.3%, the thermal conductivity is 360 W / (m·K), and the electrical conductivity is %IACS.

[0098] The above scheme discloses a preparation method of high-thermal-conductivity copper heat dissipation material injection molding, which can solve the problems of low material utilization rate, complex structure, difficult preparation, and high production cost of the heat sink machining material in the prior art, and if alloy elements are added to improve the thermal conductivity and electrical conductivity, the performance of the two cannot be improved simultaneously, complex-shaped copper parts cannot be prepared, and the operation is difficult.

[0099] The preparation method of the application prevents the high oxidation characteristics of copper activity, realizes sintering activation of electrolytic copper powder, liquid phase sintering of low melting copper nickel powder, high shape retention of plastic base system samples, high debinding rate of green body, and adopts multiple sintering densification mechanisms such as hydrogen atmosphere sintering and hot isostatic pressing sintering, which can significantly improve sintering densification.

[0100] The application can greatly dissipate powder agglomeration through electrolytic copper powder agglomeration and dispersion treatment, improve tap density, and be more easily coated by a binder, so that powder loading capacity is improved.

[0101] The application can make fine copper powder uniformly fill and distribute between coarse copper powder through raw material powder preparation, maximize the combination with the binder through particle size matching, reduce the spacing between particles, reduce the sintering resistance under certain sintering activation energy, effectively improve the sintering efficiency, reduce the sintering temperature by adding low melting point copper nickel powder, promote sintering densification by using liquid phase sintering, and save sintering energy and cost.

[0102] The application can integrally form complex structure parts through injection molding, and the material utilization rate is as high as 98%, which solves the problems of low material utilization rate, difficult preparation of complex structure, and high production cost of the heat sink, and provides a new idea for the preparation of heat sink devices with high material cost and complex structure.

[0103] The application realizes full densification of the sintered part through normal pressure sintering + hot isostatic pressing sintering, so that the crystal grains fully grow and tightly combine, and excellent comprehensive performance, high thermal and electrical conductivity, and good tensile performance are obtained, which meet the use requirements of the heat sink.

[0104] The prepared copper heat dissipation material has a density of more than 99%, a thermal conductivity of ≥365 W / (m·K), and an electrical conductivity of 90.5% IACS, has excellent thermal and electrical conductivity, a copper sample fracture tensile strain of 45.78%, a tensile strength of 164.43 MPa, good ductility and tensile performance, and is not easy to break, which can meet the performance requirements of high thermal conductivity complex structure copper heat sink.

[0105] In summary, compared with other traditional methods, the method of the application realizes the preparation of integrated acicular heat dissipation material through multiple sintering densification mechanisms such as powder particle size matching, atmosphere protection mixing, liquid phase sintering, activation sintering, and hot isostatic pressing sintering, so that the thermal and electrical conductivity and strength plasticity of the copper heat dissipation material are synergistically improved; the method is simple, easy to operate, green, low in cost, short in process, and high in efficiency, meets the preparation of high thermal conductivity large size complex structure copper heat dissipation material, and is beneficial to industrial large-scale production and promotion.

[0106] It should be understood that the term "and / or" in this document is merely used to describe associated objects, and can represent three relationships, for example, A and / or B can mean that there are three cases, A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. In addition, the character " / " in this document generally represents an "or" relationship between the associated objects before and after it, but it can also represent an "and / or" relationship, which can be understood according to the context before and after it.

[0107] In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of the items, including any combination of single or multiple items. For example, at least one of a, b, or c can mean a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0108] It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of the processes should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0109] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a high thermal conductivity copper heat dissipation material by injection molding, characterized in that, The preparation method of the high thermal conductivity copper heat dissipation material by injection molding is as follows: S1. Electrolytic copper powder agglomeration and dispersion treatment: Weigh the electrolytic copper powder and perform airflow crushing and grinding treatment in sequence to obtain agglomerated and dispersed electrolytic copper powder. S2. Raw material powder preparation: The agglomerated and dispersed electrolytic copper powder, atomized copper powder, and copper alloy powder from S1 are stirred and mixed evenly to prepare the raw material powder. The particle size of the electrolytic copper powder is less than or equal to 600 mesh, and the D50 is 15-20µm. The particle size of the atomized copper powder is 200-400 mesh, and the D50 is 25-30µm. The copper alloy powder is a copper-nickel alloy, wherein the mass fraction of nickel is 60%, the mass fraction of copper is 33%, and the mass fraction of iron is 7%. In the raw material powder, the mass fraction of electrolytic copper powder is 20-40%, the mass fraction of atomized copper powder is 70-90%, and the mass fraction of copper-nickel alloy powder is 1-2%. S3, Injection Molding: The S2 raw material powder and plastic binder are mixed at high temperature and high speed to obtain high-purity feedstock; then, the high-purity feedstock is injection molded to obtain a green part with no defects, no deformation and uniform composition; then, the green part is subjected to catalytic degreasing and thermal degreasing to obtain a sample after thermal degreasing. S4. Atmospheric pressure sintering + hot isostatic pressing sintering: The sample after hot stripping in S3 is subjected to atmospheric pressure sintering in a hydrogen atmosphere and hot isostatic pressing sintering in a nitrogen atmosphere in sequence. In the atmospheric pressure sintering step, the flow rate of the hydrogen gas introduced is ≥2m. 3 / min, sintering temperature is 1060-1075℃, holding time is 4-6h; during hot isostatic pressing sintering, the temperature is held at 900-950℃ for 1-3h in a nitrogen atmosphere. A fully dense, high thermal conductivity copper heat dissipation material was obtained; The density of the fully dense, high thermal conductivity copper heat dissipation material is 99.5-99.9%, the tensile strength is 185-210 MPa, the tensile strain at break is 40.5-48.2%, the thermal conductivity is 360-376 W / (m·K), and the electrical conductivity is 82.5-90.8% IACS.

2. The preparation method of high thermal conductivity copper heat dissipation material by injection molding according to claim 1, characterized in that, During the S1 airflow crushing process, the classifying wheel speed is 9000-12000 r / min; during the grinding process, 0.5% anhydrous ethanol and 1-1.5% stearic acid are added by mass fraction, and electrolytic copper powder is ground at a pressure of 400-800 kPa with a feed rate of 30-60 g / min.

3. The preparation method of high thermal conductivity copper heat dissipation material by injection molding according to claim 1, characterized in that, The average particle size of the agglomerated and dispersed electrolytic copper powder in S1 is 15-25 μm.

4. The preparation method of high thermal conductivity copper heat dissipation material by injection molding according to claim 1, characterized in that, In S3, the plastic binder contains 75-85% polyoxymethylene, 8-10% polyethylene, 4-6% polypropylene, 4-6% ethylene-vinyl acetate copolymer, and 4-6% stearic acid; argon is selected as the protective atmosphere for mixing.

5. The preparation method of high thermal conductivity copper heat dissipation material by injection molding according to claim 1, characterized in that, During the S3 injection process, the injection temperature is 180-190℃, the injection pressure is 90-120 bar, the injection speed is 40-80 mm / s, and the mold temperature is 110-130℃. Catalytic degreasing removes the main component of the binder, polyoxymethylene. Heating degreasing involves heating from room temperature to 500℃ at a heating rate of 1℃ / min, and holding at 200℃, 350℃, and 500℃ for 30 minutes respectively.

6. The preparation method of high thermal conductivity copper heat dissipation material by injection molding according to claim 1, characterized in that, The degreasing rate of the samples after S3 heat degreasing was 7.5-9.0%, and the density was 5.20-5.80 g / cm³. 3 .

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