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

Abstract

The invention relates to the technical field of copper powder preparation, and discloses a device and method for preparing fine copper powder and the fine copper powder. The device for preparing the fine copper powder comprises a heating unit, a cooling tank and a collecting unit. A heating piece and a gas conveying assembly are arranged in the heating unit. A cooling tank is communicated with the heating unit, Cu steam is supplied into the cooling tank through a nucleating pipe, the nucleating pipe is provided with an inert gas inlet, and the cooling tank comprises an air cooling gas spraying pipe and a condensate water spraying assembly; and the collecting unit communicates with the bottom of the cooling tank so as to collect the fine copper powder formed after cooling treatment. By means of the device, fine copper powder narrow in particle size distribution and high in sphericity degree can be obtained in batches.

Description

Technical Field

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

[0002] Copper powder, especially fine copper powder with a particle size of micro-nano, is increasingly used in the semiconductor field due to its good conductivity and low cost. It is used in the preparation of various semiconductor devices, such as conductive pastes used to form energy batteries and various semiconductor device packages. Among the methods for preparing fine copper powder, the condensation evaporation method is often used to prepare high-quality conductive metal powders because it can obtain powders with fewer impurities and smaller particle sizes.

[0003] However, the current condensation evaporation method has a low yield. Although the yield can be increased by increasing the material flow rate by adding various fluids, how to maintain a narrow particle size distribution and high roundness of the prepared powder while increasing the yield is still one of the unsolved problems in this field. Summary of the invention

[0004] In view of the above problems, the present application provides a device, method and fine copper powder for preparing fine copper powder. The device uses a nucleation tube to realize the supply of 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, which can increase the collision probability between particles and inert gas and reduce the probability of adhesion and uncontrolled growth of ions during high-speed transportation. In addition, the cooling components inside the cooling tank are designed to reduce the collision, retention and growth of Cu particles at undesirable locations such as the wall of the equipment 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, the present application proposes a device for preparing fine copper powder. The Dv50 of the fine copper powder is 0.05 microns to 3 microns. The device includes: a heating unit, the heating unit has a heating element and a gas delivery assembly, 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 the 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, so that the inert gas and Cu vapor are mixed and sprayed into the cooling tank, the cooling tank includes an air-cooled gas nozzle and a condensed water spray assembly; a collecting unit, collecting The unit is connected to the bottom of the cooling tank to collect the fine copper powder formed after the cooling treatment, wherein the side wall of the cooling tank has a plurality of air-cooled gas nozzles arranged in an annular manner, one end of the air-cooled gas nozzle is arranged on the side wall of the cooling tank, and the other end extends obliquely downward, and the area of ​​the cooling tank bottom not covered by the projection of the air-cooled gas nozzle accounts for at least 1 / 3 of the area of ​​the cooling tank bottom; the condensed water spray assembly is arranged at the upper part of the cooling tank and has a plurality of annularly arranged vertically downward nozzles, and there is no overlapping area between the projection of the condensed water spray assembly at the bottom of the cooling tank and the projection of the air-cooled gas nozzle at the bottom of the cooling tank. The device can obtain fine copper powder with 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, a middle 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 middle section contains a heat preservation material to facilitate the nucleation of Cu vapor, and 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. In this way, the Cu vapor can be further prevented from sticking during the transportation process.

[0007] According to an embodiment of the present application, a plurality of air-cooling gas nozzles 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°. Thus, the probability of Cu vapor and particles contacting the side wall of the cooling tank can be reduced and the cooling efficiency can be improved.

[0008] According to an embodiment of the present application, the condensate spray assembly is located at the upper part of the cooling tank, the condensate spray assembly 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. Thus, dry spots can be prevented from forming on the surface of the condensate assembly.

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

[0010] In another aspect of the present application, the present application proposes a method for preparing fine copper powder using the above device. The method comprises: supplying raw materials to a heating unit, and obtaining Cu vapor at 2200℃-2800℃ and a vacuum degree of 70KPa-120KPa; using a nucleation tube to transport the Cu vapor to a cooling tank, and mixing an inert gas into the Cu vapor before spraying; using an air-cooled gas nozzle to pass an inert gas into the cooling tank, and using a condensed water spray assembly to spray and cool the Cu vapor, and obtaining fine copper powder through a collection unit. This method can obtain 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 Cu vapor in the cooling tank is 400° C. / s-2000° C. / s. Thus, fine copper powder with a smaller particle size can be obtained.

[0012] According to the embodiment of the present application, the spraying volume of the condensate spraying 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 the fine copper powder.

[0013] In another aspect of the present application, the present application provides a fine copper powder, which is prepared by 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] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0015] Figure 1 This is a schematic diagram of the structure of the device of some embodiments of the present application; Figure 2 A flowchart of the preparation method of some embodiments of the present application; Figure 3 This is a scanning electron microscope image of the Cu powder prepared in Example 1 of the present application; Figure 4 This is the thermogravimetric analysis curve of the Cu powder prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0016] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field 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" in the description and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0018] In the description of the embodiments of the present application, "multiple" means two or more, such as two, three, four or even more, unless otherwise clearly and specifically defined.

[0019] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0020] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0021] 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).

[0022] 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 and are only for the convenience of describing the embodiments of the present application and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0023] In a first aspect of the present application, the present application provides a device for preparing fine copper powder. Figure 1The device comprises a heating unit 100, a cooling tank 200 and a collecting 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 a Cu raw material, such as a copper rod, to generate Cu vapor. The gas delivery assembly 120 includes an inert gas pipeline to control the vacuum degree 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 mix an inert gas such as Ar gas and the Cu vapor and spray it 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 arranged on the side wall of the cooling tank 200, and the other end extends downwardly at an angle. The area of ​​the bottom of the cooling tank 200 that is not covered by the projection of the air-cooled 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. The condensed water spray assembly 210 is arranged at the upper part of the cooling tank and has a plurality of vertically downward nozzles arranged in an annular manner. There is no overlapping area between the projection of the condensed water spray assembly 210 at the bottom of the cooling tank and the projection of the air-cooled gas nozzle 220 at the bottom of the cooling tank. The collecting unit 300 is connected to the bottom of the cooling tank 200 to collect the fine copper powder formed after the cooling treatment. The device can obtain fine copper powder with a narrow particle size distribution and a high roundness in batches.

[0024] In the present application, unless otherwise specified, the Dv50 of the fine copper powder is 0.05 micrometers to 3 micrometers. For example, specifically, it can be 0.5-3 micrometers. 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.

[0025] Those skilled in the art will appreciate 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 locations 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 N2, to the inner cavity of the heating unit after the vacuum degree reaches the required level. 2 .

[0026] 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 a heat-insulating material to facilitate the nucleation of Cu vapor, and the outlet section extends to the interior of the cooling tank and is located at the center of the top of the cooling tank. The nucleation tube has the advantages of simple structure, easy installation, and no moving parts, so 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.

[0027] In order to reduce the adhesion between particles caused by the rapid cooling of Cu vapor after entering the cooling tank and affecting the particle size distribution and roundness, an inert gas inlet can be set at the entrance section of the nucleation tube. 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 inert gas can be used to increase the flow rate of the material. On the other hand, particles with larger atomic radius can be introduced into the material to increase the probability of collision between Cu nuclei and inert gases. The size of the nucleus can be well maintained before cooling, reducing the probability of collision and growth between nuclei. In addition, compared to directly introducing Ar gas into the heating unit 100, introducing Ar gas at this place can also reduce production costs to a certain extent.

[0028] 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-cooled gas nozzle 220 can reduce the probability of collision between the Cu nucleus and the side wall of the cooling tank, thereby reducing the probability of the nucleus adhering to the wall. If the nucleus is attached to the wall, on the one hand, it will cause the particles not to grow under the cooling effect, and on the other hand, it will not be conducive to the collection of particles, thereby causing the pollution of the wall and increasing the equipment maintenance cost. Specifically, the air-cooled gas nozzle 220 is arranged at equal intervals along the circumference of the cooling tank, and the angle between the air-cooled gas nozzle and the vertical direction is 20°-60°, for example, it can be 30°-50°. Thus, the probability of contact between Cu vapor and particles and the side wall of the cooling tank can be reduced and the cooling efficiency can be improved. When the angle between the air-cooled gas nozzle and the vertical direction is within the above range, it is conducive to the ejected airflow driving the material to flow to the central part of the cooling tank 200, so as to better cool and form particles with a desired particle size. Furthermore, the area at the bottom of the cooling tank 200 that is 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, and sufficient space can be reserved for cooling the material and forming sufficient disturbance inside the cooling tank 200, so that the Cu crystal nuclei can grow more evenly.

[0029] According to an embodiment of the present application, a condensate spray assembly can be used to increase the humidity inside the cooling tank 200 to 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 lead to excessively high local temperatures on the surface of the cooling tank 200 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.

[0030] According to the embodiments of the present application, in some embodiments, a condensation assembly may be further provided in the condensation tank 200 to further improve the condensation efficiency. For example, the condensation assembly may include a plurality of water cooling elements extending in a vertical direction. The plurality of water cooling elements may be provided in parallel. Thus, the cooling efficiency may be further improved.

[0031] 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, producing Cu vapor at 2200℃-2800℃ and a vacuum degree of 70KPa-120KPa; using a nucleation tube to transport the Cu vapor to a cooling tank, and mixing an inert gas into the Cu vapor before spraying; using an air-cooled gas nozzle to pass an inert gas into the cooling tank, and using a condensed water spray assembly to spray the Cu vapor to cool it, and obtaining fine copper powder through a collection unit. This method can obtain fine copper powder with a narrow particle size distribution and high roundness in batches.

[0032] According to some specific embodiments of the present application, the vacuum degree in the heating unit can be first controlled to 70KPa-150KPa using an air pump connected to a gas delivery assembly, and then an inert gas such as nitrogen and helium can be introduced. After the air pressure in the chamber is stabilized, the raw material can be heated by a heating element to obtain Cu vapor. The introduction of an 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 the 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 chamber. Subsequently, the heating treatment can be started, and the temperature of the heating treatment can be 2200°C-2800°C. By controlling the evaporation conditions and introducing an inert gas, the temperature required for Cu evaporation can be reduced, and some impurity atoms can be inhibited from mixing into the Cu-containing mixture.

[0033] According to the embodiments of the present application, the evaporation temperature and vacuum degree in the heating unit have an important influence on the particle size distribution of the obtained Cu powder. By optimizing the evaporation temperature and vacuum degree, 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 treatment, the present application first adjusts the vacuum degree in the chamber and introduces an inert gas to reduce the disturbance caused by the introduction of the gas after the formation of Cu vapor.

[0034] In some embodiments, in order to further improve the quality of the Cu powder obtained by the method, the heating treatment can be heated at a higher heating rate and kept warm for a period of time. For example, the temperature can be raised at 200°C / min-300°C / min, so that the raw material can quickly form Cu vapor. The insulation treatment can be supplied to the cooling tank so that the system reaches a relatively stable state. In some specific embodiments, the temperature of the heating treatment is 2200°C-2800°C, and the vacuum degree is 70KPa-120KPa, for example, the vacuum degree can be 70KPa-100KPa.

[0035] 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 nucleus growth in Cu vapor, the decrease in temperature will increase the supercooling, thereby increasing the nucleation rate. However, the decrease in temperature will also reduce the diffusion rate, and diffusion is an important step in the crystallization process, and the decrease in 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 growth rate of the crystal 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.

[0036] According to the embodiment of the present application, the cooling rate of Cu vapor in the cooling tank can be 400°C / s-2000°C / s by designing the size of the nucleation tube, the amount of inert gas introduced, the air-cooled gas nozzle, and the control of the parameters of the condensed water spray assembly. Thus, fine copper powder with a smaller particle size can be obtained.

[0037] 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 at about 1 bar to 2 bar, thereby maintaining a continuous supply of materials and improving production efficiency.

[0038] Furthermore, according to an embodiment of the present application, a condensation component may be further provided to enhance the cooling effect. The cooling medium in the condensation component may 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 components extending in a vertical direction, and the plurality of water-cooling components may be arranged in parallel, thereby improving the uniformity of cooling. Specifically, the condensate inlets of the plurality of water-cooling components may flow into the water-cooling components from a water supply pipeline, such as circulating from the bottom to the top of the water-cooling components. 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 components.

[0039] According to the embodiment of the present application, the spraying volume of the condensate spraying assembly can be 0.2L / m 3 ·s-2.0L / m 3 ·s. In this way, the surface of the fine copper powder can be kept moderately moist, while preventing the fine copper powder from being oxidized due to excessive humidity.

[0040] According to an embodiment of the present application, the difference between Dv10 and Dv90 of the fine copper powder formed by the method can be less than 4.5 microns, and the sphericity of the particles is greater than 90%, which is spherical or quasi-spherical. The impurity content of the formed fine copper powder is low, for example, the fine copper powder can contain 0.005wt%~0.05wt% carbon, the oxygen content is 0.08wt%-2.0wt%, and: iron content <0.01wt%, aluminum content <0.01wt%, silicon content <0.01wt%, calcium content <0.01wt%, magnesium content <0.01wt%, zirconium content <0.01wt%.

[0041] In some embodiments, the fine copper powder may have a thin oxide layer on its surface. The oxide layer may mainly consist of CuO, Cu(OH) 2 The appropriate oxide layer can improve the anti-oxidation performance of the nano-scale Cu powder. Moreover, without affecting the main performance parameters of the Cu powder, the oxide layer of appropriate thickness can also reduce the requirements for the equipment and method for preparing the Cu powder, which is conducive to reducing production costs.

[0042] In another aspect of the present application, the present application proposes a fine copper powder. 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%~0.05wt% carbon, an oxygen content of 0.08wt%-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.

[0043] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0044] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the 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).

[0045] Example 1 Cu rods were used as raw materials, and the vacuum was evacuated to 100KPa. Argon was introduced for 30 minutes for gas replacement. After the pressure stabilized, the temperature was raised at 300℃ / min, the target temperature was 2400℃, and the heat preservation treatment was carried out for 30 minutes. During the heat preservation treatment, the cooling tank condensate water spray component was turned on, and the spray volume was controlled at 0.5L / m 3 ·s, pass condensed water into the water-cooled parts and open the air-cooled gas nozzle to pass N 2 Gas replacement is performed. After the heat preservation treatment is completed, Ar gas is introduced into the nucleation tube to make the pressure of the ejected material 0.8 bar. 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.

[0046] Comparative Example 1 Cu rods are used as raw materials, and the vacuum is evacuated to 100KPa. Argon gas 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 preservation treatment is carried out for 30 minutes. During the heat preservation treatment, no operation is performed on the cooling tank. After the heat preservation 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, pass condensed water into the water-cooled parts and open the air-cooled gas nozzle to pass 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.

[0047] 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, and the particle size is 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 has 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 ability.

[0048] 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.

[0049] It can be seen that the method and device proposed in this application can better control the morphology of the produced fine copper powder.

[0050] 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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, wherein the heating unit has 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 is connected to the heating unit 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 the Cu vapor into the cooling tank, and the cooling tank includes an air-cooled gas nozzle and a condensed water spray assembly; A collecting unit, the collecting unit is connected to the bottom of the cooling tank to collect the fine copper powder formed after the cooling treatment, wherein the side wall of the cooling tank has a plurality of annularly arranged air-cooling gas nozzles, one end of the air-cooling gas nozzle is arranged on the side wall of the cooling tank, and the other end extends obliquely downward, and the area of ​​the bottom of the cooling tank not covered by the projection of the air-cooling gas nozzle accounts for at least 1 / 3 of the area of ​​the bottom of the cooling tank; A condensate spray assembly is disposed on the upper portion of the cooling tank and has a plurality of vertically downward nozzles arranged in a ring, and there is no overlapping area between the projection of the condensate 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 which are 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 a heat-insulating 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 1, characterized in that The plurality of air-cooled gas nozzles are arranged at equal intervals along the circumference of the cooling tank, and the angle between the air-cooled gas nozzles and the vertical direction is 20°-60°.

4. The device according to claim 2, characterized in that The condensate spray assembly is located at the upper part of the cooling tank, the condensate spray assembly 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 0.5m.

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

6. A method for preparing fine copper powder, characterized in that: Applicable to the device for preparing fine copper powder according to any one of claims 1 to 5, wherein the Dv50 of the fine copper powder is 0.05 micrometers to 3 micrometers, and the method comprises: The raw material is supplied to a heating unit to produce Cu vapor at 2200°C-2800°C and a vacuum degree of 70KPa-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; Inert gas is introduced into the cooling tank by using an air-cooled gas nozzle, and the Cu vapor is sprayed and cooled by using a condensed water spray assembly, and the fine copper powder is obtained through a collection unit.

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

8. The method according to claim 6, characterized in that The spray volume of the condensate spray assembly is 0.2L / m 3 ·s-2.0L / m 3 ·s.

9. A fine copper powder, characterized in that: The fine copper powder is prepared by using the device for preparing fine copper powder according to any one of claims 1 to 5, or by using the method for preparing fine copper powder according to any one of claims 6 to 8.

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