Device and method for preparing fine copper powder and fine copper powder

Abstract

This application relates to the technical field of copper powder preparation, and discloses an apparatus, method, and fine copper powder for preparing fine copper powder. The apparatus for preparing fine copper powder comprises: a heating unit, a cooling tank, and a collection unit. The heating unit comprises a heating element and a gas delivery assembly; a cooling tank connected to the heating unit, into which Cu vapor is supplied via a nucleation tube having an inert gas inlet. The cooling tank comprises an air-cooled gas nozzle and a condensed water spray assembly; and a collection unit connected to the bottom of the cooling tank to collect the fine copper powder formed after the cooling process. This apparatus can produce fine copper powder with a narrow particle size distribution and high sphericity in batches.

Description

Technical Field

[0001] The present application relates to the technical field of copper powder preparation, and in particular to an apparatus and method for preparing fine copper powder, as well as the fine copper powder. Background Art

[0002] Copper powder, particularly fine copper powder with micro-nano particle size, is increasingly being used in the semiconductor industry due to its excellent conductivity and low cost. It is used in the preparation of various semiconductor devices, such as conductive pastes used in energy batteries and various semiconductor device packages. Among the methods for preparing fine copper powder, the condensation-evaporation method is often used to produce high-quality conductive metal powders because it produces powders with fewer impurities and smaller particle size.

[0003] However, the current condensation-evaporation method has a low yield. Although it is possible to increase yield by increasing the flow rate of various fluids, maintaining a narrow particle size distribution and high roundness in the prepared powder while increasing yield remains an unresolved challenge in this field. Summary of the Invention

[0004] In view of the above problems, the present application provides an apparatus, method, and fine copper powder for preparing fine copper powder. The apparatus utilizes a nucleation tube to supply Cu vapor to a cooling tank. The Cu vapor is supplied to the cooling tank with the assistance of an inert gas with a larger atomic radius, such as Ar gas. This increases the probability of collision between particles and the inert gas, reducing the probability of ion adhesion and uncontrolled growth during high-speed transport. Furthermore, the cooling components within the cooling tank are designed to reduce the collision, retention, and growth of Cu particles in undesirable locations such as the equipment wall while maintaining the cooling rate, thereby maintaining the narrow distribution and good roundness of the prepared fine copper powder.

[0005] In one aspect of the present application, a device for preparing fine copper powder is proposed. The Dv50 of the fine copper powder is 0.05 microns to 3 microns. The device includes: a heating unit, a heating element and a gas delivery assembly in the heating unit, the heating element is suitable for heating the Cu raw material to generate Cu vapor, the gas delivery assembly includes an inert gas pipeline to control the vacuum degree in the heating unit and pass inert gas; a cooling tank, the cooling tank and the heating unit are connected to cool the Cu vapor, the Cu vapor is supplied to the cooling tank through a nucleation tube, the nucleation tube has an inert gas inlet to spray the inert gas and Cu vapor into the cooling tank, the cooling tank includes an air-cooled gas nozzle and a condensed water spray assembly; a collecting unit, The unit is connected to the bottom of the cooling tank to collect the fine copper powder formed after the cooling process. The sidewall of the cooling tank has multiple annular air-cooling gas nozzles, one end of which is set on the sidewall of the cooling tank and the other end extends downward at an angle. The area of ​​the cooling tank bottom not covered by the air-cooling gas nozzles accounts for at least 1 / 3 of the cooling tank bottom area. The condensate spray assembly is located at the top of the cooling tank and has multiple annularly arranged vertically downward nozzles. The projection of the condensate spray assembly on the cooling tank bottom does not overlap with the projection of the air-cooling gas nozzles on the cooling tank bottom. This device can produce fine copper powder with a narrow particle size distribution and high roundness in batches.

[0006] According to an embodiment of the present application, the nucleation tube includes an inlet section, an intermediate section, and an outlet section, which are sequentially connected. The inlet section extends into and communicates with the heating unit. The intermediate section contains insulation material to facilitate Cu vapor nucleation. The outlet section extends to the cooling tank and has an inert air inlet, which transports the nucleated fine copper powder to the cooling tank. This further prevents Cu vapor from sticking during transportation.

[0007] According to an embodiment of the present application, multiple air-cooling gas nozzles are arranged at equal intervals along the circumference of the cooling tank, with the angle between the air-cooling gas nozzles and the vertical direction being 20°-60°. This reduces the probability of Cu vapor and particles contacting the sidewalls of the cooling tank and improves cooling efficiency.

[0008] According to an embodiment of the present application, the condensate spray assembly is located above the cooling tank and has an annular portion. The nozzle is located below the annular portion, and the distance between the annular portion and the bottom of the outlet section is no less than 0.5m. This prevents dry spots from forming on the surface of the condensate assembly.

[0009] According to an embodiment of the present application, a condensing assembly is further provided in the cooling tank, and the condensing assembly includes a plurality of water-cooling elements extending in a vertical direction, and the plurality of water-cooling elements are arranged in parallel, thereby further improving the cooling efficiency.

[0010] In another aspect, the present application proposes a method for preparing fine copper powder using the aforementioned apparatus. The method comprises: supplying raw materials to a heating unit to produce Cu vapor at 2200°C-2800°C and a vacuum of 70kPa-120kPa; transporting the Cu vapor to a cooling tank using a nucleation tube, and mixing an inert gas into the Cu vapor before spraying it into the cooling tank; introducing an inert gas into the cooling tank using an air-cooled gas nozzle, and cooling the Cu vapor by spraying it with a condensed water spray assembly, and obtaining fine copper powder through a collection unit. This method can produce fine copper powder with a narrow particle size distribution and high roundness in batches.

[0011] According to an embodiment of the present application, the cooling rate of the Cu vapor in the cooling tank is 400° C. / s-2000° C. / s, thereby obtaining fine copper powder with a smaller particle size.

[0012] According to the embodiment of the present application, the spraying volume of the condensate spray assembly is 0.2L / m 3 ·s-2.0L / m 3 ·s. This keeps the surface of the condensation component moderately moist while preventing excessive humidity from oxidizing fine copper powder.

[0013] In another aspect of the present application, a fine copper powder is provided, which is prepared using the above-mentioned device for preparing fine copper powder or the above-mentioned method for preparing fine copper powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0015] Figure 1 This is a schematic structural diagram of the device according to some embodiments of the present application;

[0016] Figure 2 Flowchart of the preparation method of some embodiments of the present application;

[0017] Figure 3 This is a scanning electron microscope image of the Cu powder prepared in Example 1 of the present application;

[0018] Figure 4 This is the thermogravimetric analysis curve of the Cu powder prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0019] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusions.

[0021] In the description of the embodiments of the present application, "a plurality" means two or more, such as two, three, four or even more, unless otherwise specifically defined.

[0022] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0024] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0025] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "upper", "lower", "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present application.

[0026] In the first aspect of the present application, the present application provides a device for preparing fine copper powder. Figure 1The device includes a heating unit 100, a cooling tank 200 and a collection unit 300 connected in sequence. The heating unit 100 has a heating element 110 and a gas delivery assembly 120. The heating element 110 is suitable for heating Cu raw materials, such as copper rods, to produce Cu vapor. The gas delivery assembly 120 includes an inert gas pipeline to control the vacuum level in the heating unit and pass inert gas. The cooling tank 200 is connected to the heating unit 100 to cool the generated Cu vapor. The Cu vapor is supplied to the cooling tank 200 through a nucleation tube 10. The nucleation tube has an inert gas inlet to spray an inert gas such as Ar gas and the Cu vapor into the cooling tank 200. The cooling tank 200 includes an air-cooled gas nozzle 220 and a condensed water spray assembly 210. The side wall of the cooling tank has a plurality of annularly arranged air-cooled gas nozzles 220. One end of the air-cooled gas nozzle 220 is set on the side wall of the cooling tank 200, and the other end extends obliquely downward. The area at the bottom of the cooling tank 200 not covered by the projection of the air-cooling gas nozzle 220 (as defined by the dotted line in the figure) accounts for at least one-third of the area of ​​the cooling tank bottom. The condensate spray assembly 210 is located at the top of the cooling tank and has multiple, vertically downward-pointing nozzles arranged in a circular pattern. There is no overlap between the projection of the condensate spray assembly 210 at the bottom of the cooling tank and the projection of the air-cooling gas nozzle 220 at the bottom of the cooling tank. The collection unit 300 is connected to the bottom of the cooling tank 200 to collect the fine copper powder formed after the cooling process. This device can produce fine copper powder with a narrow particle size distribution and high roundness in batches.

[0027] In this application, unless otherwise specified, the Dv50 of fine copper powder is 0.05 μm to 3 μm. For example, it can be 0.5 to 3 μm. The Dv50 can be measured using a laser particle size analyzer based on a method commonly used by those skilled in the art to determine the Dv50.

[0028] It will be understood by those skilled in the art that the drawings are merely schematic diagrams of the device in which the present application is located, and should not be construed as limiting the specific positions of specific components. Figure 1 The positions of the heating element 110 and the gas delivery assembly 120 shown in the figure are only examples. Those skilled in the art can select the type and position of the heating element 110 according to actual conditions, as long as the raw material can be stably heated to form Cu vapor. The gas delivery assembly 120 may include a structure such as an air pump connected to the inner cavity of the heating unit 100 to provide sufficient vacuum. At the same time, in order to reduce the heating temperature and improve the purity of the fine copper powder obtained, the gas delivery assembly 120 may also have an inert gas supply pipeline for supplying an inert gas, such as N, to the inner cavity of the heating unit after the vacuum degree reaches the required level. 2 .

[0029] According to an embodiment of the present application, the nucleation tube 10 includes an inlet section, an intermediate section, and an outlet section connected in sequence. The inlet section extends to the interior of the heating unit and is connected to the heating unit. The intermediate section contains insulation material to facilitate the nucleation of Cu vapor. The outlet section extends to the interior of the cooling tank and is located in the center of the top of the cooling tank. The nucleation tube has the advantages of simple structure, easy installation, and no moving parts. Therefore, the mechanical wear is small, the maintenance cost is low, and the fluid pressure loss is small. Therefore, the use of a nucleation tube for the supply of Cu vapor can reduce the complexity of the equipment and maintain a continuous supply of materials.

[0030] In order to reduce the adhesion between particles caused by the rapid cooling after the Cu vapor enters the cooling tank and affects the particle size distribution and roundness, the inlet section of the nucleation tube can be provided with an inert gas inlet. Thus, before the Cu vapor enters the cooling tank 200, it can be mixed with a portion of inert gases such as Ar gas in advance. On the one hand, the flow rate of the material can be improved by inert gas. On the other hand, particles with larger atomic radius can be introduced into the material to improve the probability of collision between the Cu nucleus and the inert gas. Before cooling, the size of the nucleus can be maintained to be better maintained, reducing the probability of collision and growth between the nucleus. Moreover, compared to directly passing Ar gas in the heating unit 100, passing Ar gas therein can also reduce production costs to a certain extent.

[0031] According to an embodiment of the present application, in order to enable the cooling tank 200 to maintain a good condensation rate, the present application adopts a combination of air cooling and water cooling. In addition, the position of the air-cooling gas nozzle 220 can reduce the probability of collision between the Cu nuclei and the side walls of the cooling tank, thereby reducing the probability of the nuclei adhering to the wall. If the nuclei adhere to the wall, on the one hand, the particles will not grow under the cooling effect, and on the other hand, it will be detrimental to the collection of particles, thereby causing contamination of the wall and increasing equipment maintenance costs. Specifically, the air-cooling gas nozzles 220 are arranged at equal intervals along the circumference of the cooling tank, and the angle between the air-cooling gas nozzles and the vertical direction is 20°-60°, for example, it can be 30°-50°. As a result, the probability of Cu vapor and particles contacting the side walls of the cooling tank can be reduced and the cooling efficiency can be improved. When the angle between the air-cooling gas nozzles and the vertical direction is within the above range, it is beneficial for the ejected airflow to drive the material to flow toward the central part of the cooling tank 200, thereby better cooling to form particles with the desired particle size. Furthermore, the area at the bottom of the cooling tank 200 not covered by the projection of the air-cooling gas nozzle 220 (as defined by the dotted line in the figure) accounts for at least 1 / 3 of the area of ​​the bottom of the cooling tank, which can also reserve sufficient space for cooling the material and form sufficient disturbance inside the cooling tank 200, thereby allowing the Cu crystal nuclei to grow more uniformly.

[0032] According to an embodiment of the present application, the condensate spray assembly can be used to increase the humidity inside the cooling tank 200 and prevent dry spots from forming on the surface of the cooling tank 200. Since Cu needs to be heated to a relatively high temperature to form Cu vapor, the temperature of the material supplied to the inside of the cooling tank 200 is also relatively high. Simple air cooling and water cooling can easily cause the local temperature on the surface of the cooling tank 200 to be too high and form dry spots, affecting the life of the equipment. In some specific embodiments, the condensate spray assembly 210 may be located below the outlet section of the nucleation tube, and the condensate spray assembly has an annular portion, and the nozzle is located below the annular portion. Thus, the annular portion can reduce the disturbance of the material ejected from the nucleation tube, allowing it to move better inside the cooling tank 200. In some specific embodiments, the distance between the annular portion and the bottom of the outlet section is not less than 0.5m. Thus, the impact on the ejected material can be further reduced, and the enrichment of the material at the condensate spray assembly 210 can also be reduced.

[0033] According to embodiments of the present application, in some embodiments, a condensation assembly may be provided within the condensation tank 200 to further improve condensation efficiency. For example, the condensation assembly may include multiple vertically extending water-cooling elements. Multiple water-cooling elements may be arranged in parallel, thereby further improving cooling efficiency.

[0034] In another aspect of the present application, the present application provides a method for preparing fine copper powder, which can be carried out using the aforementioned device. Figure 2 The method includes supplying raw materials to a heating unit to generate Cu vapor at 2200-2800°C and a vacuum of 70-120 kPa; transporting the Cu vapor to a cooling tank using a nucleation tube, and mixing the Cu vapor with an inert gas before injection; introducing an inert gas into the cooling tank using an air-cooled gas nozzle, and cooling the Cu vapor by spraying it with a condensed water spray assembly, before obtaining fine copper powder through a collection unit. This method can produce fine copper powder with a narrow particle size distribution and high roundness in batches.

[0035] According to some specific embodiments of the present application, the air pump connected to the gas delivery assembly can be used to control the vacuum degree in the heating unit to 70KPa-150KPa, and then nitrogen, helium and other inert gases can be introduced. After the air pressure in the chamber is stabilized, the raw material can be heat-treated using a heating element to produce Cu vapor. The introduction of inert gas can replace the air remaining in the chamber, avoid oxidation of the raw material during subsequent heating, and reduce the temperature at which vapor is formed. Specifically, the flow rate of the inert gas can be controlled to maintain the vacuum degree, and for a period of time to achieve replacement of the gas in the cavity. Subsequently, the heating treatment can be started, and the temperature of the heating treatment can be 2200℃-2800℃. By controlling the evaporation conditions and introducing inert gas, the temperature required for Cu evaporation can be lowered, and some impurity atoms can be suppressed from mixing into the Cu-containing mixture.

[0036] According to the embodiments of the present application, the evaporation temperature and vacuum level in the heating unit have a significant impact on the particle size distribution of the produced Cu powder. By optimizing the evaporation temperature and vacuum level, the evaporation rate and growth conditions of the fine copper powder can be controlled, thereby obtaining Cu powder with a narrow particle size distribution. Before starting the heating process, the present application first adjusts the vacuum level in the chamber and introduces an inert gas to reduce the disturbance caused by the introduction of gas after the Cu vapor is formed.

[0037] In some embodiments, in order to further improve the quality of the Cu powder obtained by the method, the heat treatment can be performed at a higher heating rate and kept warm for a period of time. For example, the temperature can be increased at 200°C / min-300°C / min to enable the raw material to quickly form Cu vapor. The heat preservation treatment can be performed to allow the system to reach a relatively stable state before being supplied to the cooling tank. In some specific embodiments, the temperature of the heat treatment is 2200°C-2800°C, and the vacuum degree is 70KPa-120KPa, for example, the vacuum degree can be 70KPa-100KPa.

[0038] The particle size of fine copper powder is affected by the nucleation rate and the crystal nucleus growth rate. In the process of forming Cu particles by crystal nuclei growing in Cu vapor, a decrease in temperature will increase the supercooling, thereby increasing the nucleation rate. However, a decrease in temperature will also reduce the diffusion rate, and diffusion is an important step in the crystallization process. A decrease in the diffusion rate is not conducive to increasing the nucleation rate. Therefore, the nucleation rate is greatly affected by temperature. Usually, with the increase of supercooling, the nucleation rate first increases and then decreases. The increase in nucleation rate will lead to the generation of more new crystal nuclei, so the nucleation rate and the crystal growth rate jointly affect the size and uniformity of the particles finally formed. Therefore, the control of the condensation conditions in the cooling tank has a decisive influence on the morphology of the fine copper powder formed.

[0039] According to the embodiments of the present application, by designing the nucleation tube dimensions, controlling the amount of inert gas introduced, controlling the parameters of the air-cooling gas nozzle, and controlling the condensate spray assembly, the cooling rate of the Cu vapor in the cooling tank can be set at 400°C / s to 2000°C / s. This allows for the production of fine copper powder with a relatively small particle size.

[0040] For example, the size of the nucleation tube and the amount of inert gas introduced can be controlled to keep the pressure of the ejected material around 1-2 bar, thereby maintaining a continuous supply of material and improving production efficiency.

[0041] Furthermore, according to an embodiment of the present application, a condensation component can be further provided to enhance the cooling effect. The cooling medium in the condensation component can be a condensate, for example, water or deionized water. In order to achieve condensation more effectively, the condensation component includes a plurality of water-cooling parts extending in a vertical direction, and the plurality of water-cooling parts can be arranged in parallel, thereby improving the uniformity of cooling. Specifically, the condensate inlets of the plurality of water-cooling parts can flow into the water-cooling parts from a water supply pipeline, such as circulating from the bottom to the top of the water-cooling part. Compared with an inclined arrangement or a horizontally staggered arrangement, a vertical distribution is more conducive to reducing the accumulation of materials on the surface of the water-cooling part.

[0042] According to the embodiment of the present application, the spraying volume of the condensate spray assembly can be 0.2L / m 3 ·s-2.0L / m 3 ·s. This can keep the surface of the fine copper powder moderately moist while preventing excessive humidity from oxidizing the fine copper powder.

[0043] According to an embodiment of the present application, the difference between Dv10 and Dv90 of the fine copper powder formed by this method can be less than 4.5 microns, and the sphericity of the particles is greater than 90%, which means they are spherical or quasi-spherical. The fine copper powder formed has a low impurity content. For example, the fine copper powder can contain 0.005wt% to 0.05wt% carbon, an oxygen content of 0.08wt% to 2.0wt%, and: iron content <0.01wt%, aluminum content <0.01wt%, silicon content <0.01wt%, calcium content <0.01wt%, magnesium content <0.01wt%, and zirconium content <0.01wt%.

[0044] In some embodiments, the fine copper powder may have a thin oxide layer on its surface. The oxide layer may be primarily composed of CuO, Cu(OH)2, etc. A suitable oxide layer can enhance the oxidation resistance of the nanoscale Cu powder. Furthermore, without affecting the key performance parameters of the Cu powder, an appropriately thick oxide layer can reduce the requirements for the equipment and methods used to prepare the Cu powder, thereby reducing production costs.

[0045] In another aspect of the present application, a fine copper powder is proposed. The fine copper powder can be prepared using the aforementioned method for preparing fine copper powder or the device for preparing fine copper powder. Specifically, the fine copper powder may contain 0.005wt% to 0.05wt% carbon, an oxygen content of 0.08wt% to 2.0wt%, and: iron content <0.01wt%, aluminum content <0.01wt%, silicon content <0.01wt%, calcium content <0.01wt%, magnesium content <0.01wt%, and zirconium content <0.01wt%. The fine copper powder has a low impurity content and good roundness, and can meet the needs of a variety of conductive pastes.

[0046] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0047] Unless otherwise specified, the terms used in this application have the commonly understood meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0048] Example 1

[0049] Using Cu rod as raw material, evacuate to a vacuum degree of 100KPa, and introduce argon for 30 minutes for gas replacement. After the pressure stabilizes, heat up at 300℃ / min, target temperature 2400℃, and keep warm for 30 minutes. During the heat preservation process, open the cooling tank condensate spray assembly, and control the spray volume at 0.5L / m 3 ·s, introduce condensed water to the water-cooled parts and open the air-cooled gas nozzle, introduce N 2 Perform gas replacement. After the insulation treatment, introduce Ar gas into the nucleation tube to reduce the pressure of the ejected material to 0.8 bar. Turn on the sidewall heater, targeting a heating temperature of 400°C. Finally, collect the metal particles in a collection unit.

[0050] Comparative Example 1

[0051] Cu rods are used as raw materials, and the vacuum is evacuated to 100KPa. Argon is introduced for 30 minutes for gas replacement. After the air pressure stabilizes, the temperature is increased at 300℃ / min, the target temperature is 2400℃, and the heat treatment is carried out for 30 minutes. During the heat treatment, no operation is performed on the cooling tank. After the heat treatment, Ar gas is introduced into the nucleation tube to make the pressure of the ejected material 0.8bar. While the material is introduced into the cooling tank, the condensate spray assembly is turned on and the spray volume is controlled at 0.1L / m 3 ·s, introduce condensed water to the water-cooled parts and open the air-cooled gas nozzle, introduce N 2 The heating element at the side wall is turned on, and the target heating temperature is 400° C. Finally, the metal particles are collected by the collection unit.

[0052] refer to Figure 3 as well as Figure 4The Cu powder prepared in Example 1 has a relatively uniform particle size and a high roundness, with a particle size of about 3 microns. Tested by a laser particle size analyzer, Dv90 is 4.605 microns and Dv10 is 0.359 microns. Thermogravimetric analysis shows that the DTA curve of the Cu powder has the first small peak at around 257°C and a relatively obvious exothermic broad peak at 347°C, which may be related to the oxidation of impurity elements in the Cu powder. The TGA curve also has an inflection point near 257°C. A broad peak appears in the DTA curve at around 326°C, which may be related to the oxidation of impurity elements in the Cu powder. It can be seen that the Cu powder obtained by this method has a narrow particle size distribution and has a certain antioxidant capacity.

[0053] The TGA curve of the Cu powder prepared in Comparative Example 1 is not significantly different from that in Example 1, but the particle size distribution is wider, with Dv50 of 3.042 μm, Dv10 of 0.245 μm, and Dv90 as high as 8.454 μm, and irregular particles and ellipsoidal particles account for a large proportion of the particles.

[0054] It can be seen that the method and apparatus proposed in this application can better control the morphology of the produced fine copper powder.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A device for preparing fine copper powder, characterized in that: The Dv50 of the fine copper powder is 0.05 microns to 3 microns, and the device comprises: A heating unit having a heating element and a gas delivery assembly, wherein the heating element is suitable for heating the Cu raw material to generate Cu vapor, and the gas delivery assembly includes an inert gas pipeline to control the vacuum degree in the heating unit and to introduce the inert gas; a cooling tank, the cooling tank being connected to the heating unit to cool the Cu vapor, the Cu vapor being supplied into the cooling tank through a nucleation tube, the nucleation tube having an inert gas inlet for spraying a mixture of the inert gas and the Cu vapor into the cooling tank, the cooling tank comprising an air-cooled gas nozzle and a condensed water spray assembly; a collecting unit, the collecting unit being in communication with the bottom of the cooling tank for collecting the fine copper powder formed after the cooling process, wherein the sidewall of the cooling tank is provided with a plurality of annularly arranged air-cooling gas nozzles, the plurality of air-cooling gas nozzles being equidistantly arranged along the circumference of the cooling tank, one end of the air-cooling gas nozzle being provided on the sidewall of the cooling tank, and the other end being inclined downwardly extended, the angle between the air-cooling gas nozzle and the vertical direction being 20°-60°, and the area of ​​the cooling tank bottom not covered by the projection of the air-cooling gas nozzles accounting for at least 1 / 3 of the area of ​​the cooling tank bottom; A condensed water spray assembly is arranged at the upper part of the cooling tank and has a plurality of vertically downward nozzles arranged in a ring. There is no overlapping area between the projection of the condensed water spray assembly on the bottom of the cooling tank and the projection of the air-cooled gas nozzle on the bottom of the cooling tank.

2. The device according to claim 1, characterized in that The nucleation tube includes an inlet section, an intermediate section, and an outlet section connected in sequence. The inlet section extends into the interior of the heating unit and is connected to the heating unit. The intermediate section contains insulation material to facilitate the nucleation of Cu vapor. The outlet section extends to the cooling tank and has an inert air inlet, and transports the nucleated fine copper powder to the cooling tank.

3. The device according to claim 2, characterized in that The condensate spray assembly is located at the upper part of the cooling tank, and has an annular portion. The nozzle is located below the annular portion, and the distance between the annular portion and the bottom of the outlet section is not less than 0.5 m.

4. The device according to any one of claims 1 to 3, characterized in that A condensation assembly is also provided in the cooling tank. The condensation assembly includes a plurality of water-cooling parts extending in a vertical direction. The plurality of water-cooling parts are arranged in parallel.

5. A method for preparing fine copper powder, characterized in that: Applicable to the apparatus for preparing fine copper powder according to any one of claims 1 to 4, wherein the Dv50 of the fine copper powder is 0.05 microns to 3 microns, the method comprising: The raw materials are supplied to a heating unit to produce Cu vapor at 2200-2800°C and a vacuum degree of 70-120KPa; The Cu vapor is transported to a cooling tank by a nucleation tube, and an inert gas is mixed into the Cu vapor before injection; An inert gas is introduced into the cooling tank using an air-cooled gas nozzle to reduce the temperature required for Cu evaporation, and the Cu vapor is cooled by spraying using a condensed water spray assembly, and the fine copper powder is obtained through a collection unit. The spraying volume of the condensed water spray assembly is 0.2L / m3·s-2.0L / m3·s.

6. The method according to claim 5, characterized in that The cooling rate of the Cu vapor in the cooling tank is 400° C. / s-2000° C. / s.

7. A fine copper powder, characterized in that The fine copper powder is prepared using the device for preparing fine copper powder according to any one of claims 1 to 4, or using the method for preparing fine copper powder according to claim 5 or 6.

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