Apparatus and method for coating particle

Abstract

To provide an apparatus and method for coating particles, capable of efficiently manufacturing particles covered with a coating film having a thin and uniform thickness.SOLUTION: An apparatus for coating particles, capable of forming a coating film on the particle surface of powder to be processed by an atomic layer deposition method includes: a processing chamber including a chamber and an opening and closing part for opening and closing the chamber; a raw material gas supply part for supplying raw material gas into the processing chamber; an oxidizer supply part for supplying an oxidizer into the processing chamber; a processing chamber exhaust part for exhausting the inside of the processing chamber; a plurality of trays conveyed into the processing chamber through the opening and closing part and configured to hold a powder layer obtained by spreading the powder to be processed into a layer; and a mounting part arranged into the processing chamber and capable of attachably / detachably mounting the plurality of trays.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a particle coating apparatus and a particle coating method. [Background technology]

[0002] For magnetic powders used in inductors, etc., it is necessary to apply an insulating treatment to the particle surface to suppress eddy currents flowing between particles and to insulate terminals. For this reason, methods for forming insulating coatings on the particle surfaces of magnetic powders using various film-forming methods are being investigated.

[0003] For example, Patent Document 1 discloses a particle coating device that forms an insulating film on the surface of soft magnetic metal particles by atomic layer deposition (ALD), which is a type of chemical vapor deposition method. Atomic layer deposition makes it possible to form an insulating film that is thin and uniform in thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-085050 Summary of the Invention [Problem to be solved by the invention]

[0005] In the particle coating device described in Patent Document 1, soft magnetic metal particles are placed in a tray to form a coating, but in order to form a coating with a uniform thickness, it is necessary to limit the amount of soft magnetic metal particles placed in the tray. For this reason, the particle coating device described in Patent Document 1 has a problem in that the production efficiency of coated particles cannot be sufficiently improved. In addition, Patent Document 1 does not disclose how to put the soft magnetic metal particles into the tray. In general, the task of putting soft magnetic metal particles into a tray arranged in a vacuum chamber and spreading them over the tray is difficult and has low work efficiency. [Means for solving the problem]

[0006] A particle coating apparatus according to an embodiment of the present invention includes: A particle coating apparatus for forming a coating on a surface of a powder to be treated by an atomic layer deposition method, a processing chamber having a chamber and an opening / closing part for opening and closing the chamber; a raw material gas supply unit for supplying a raw material gas into the processing chamber; an oxidant supply unit for supplying an oxidant into the processing chamber; a processing chamber exhaust unit that exhausts the inside of the processing chamber; a plurality of trays that can be carried into the treatment chamber through the opening and closing part and hold a powder layer in which the powder to be treated is laid in layers; a placement unit disposed within the processing chamber, on which the plurality of trays are detachably placed; Equipped with.

[0007] A particle coating method according to an embodiment of the present invention includes the steps of: A particle coating method for forming a coating on a surface of a powder to be treated by atomic layer deposition, comprising the steps of: carrying a plurality of trays holding powder layers in which the powder to be processed is laid in layers into the processing chamber via an opening / closing section; After closing the opening and closing part, forming the coating on the powder layer by an atomic layer deposition method in the processing chamber; opening the opening / closing portion, and carrying out the trays holding the powder layer after the coating is formed from outside the processing chamber; has. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view showing a powder layer forming unit included in the particle coating apparatus according to the embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a film-forming unit included in the particle coating apparatus according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view that illustrates an example of a coated particle produced by the particle coating apparatus illustrated in FIGS. 1 and 2. [Figure 4] 1A to 1C are process diagrams illustrating a particle coating method according to an embodiment. [Diagram 5] 4A to 4C are diagrams illustrating a method for recovering coated particles from a tray in a recovery step. [Figure 6] FIG. 11 is a cross-sectional view showing a film-forming unit included in a particle coating apparatus according to a first modified example. [Figure 7] FIG. 11 is a perspective view showing a squeegee included in a particle coating apparatus according to a second modified example. [Figure 8] FIG. 11 is a cross-sectional view showing a film-forming unit included in a particle coating apparatus according to a third modified example. [Figure 9] FIG. 13 is a cross-sectional view showing a tray included in a particle-coating apparatus according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the particle coating apparatus and particle coating method of the present invention will be described in detail with reference to the accompanying drawings.

[0010] 1.Particle coating equipment First, a particle coating apparatus according to an embodiment will be described.

[0011] FIG. 1 is a cross-sectional view showing a powder layer forming unit 1A included in the particle coating apparatus 1 according to the embodiment. FIG. 2 is a cross-sectional view showing a film forming unit 1B included in the particle coating apparatus 1 according to the embodiment. FIG. 3 is a cross-sectional view showing an example of a coated particle 93 manufactured by the particle coating apparatus 1 shown in FIG. 1 and FIG. 2. In each drawing of the present application, for convenience of explanation, an X-axis, a Y-axis, and a Z-axis are set as three mutually orthogonal axes, and each axis is indicated by an arrow. The Z-axis is a vertical axis, and the XY plane is a horizontal plane. The base end side of the arrow is referred to as the negative side of each axis, and the tip end side is referred to as the positive side of each axis.

[0012] 1 and 2 is an apparatus for forming a coating 92 shown in Fig. 3 on the surface of particles 91 by atomic layer deposition (ALD). In the following description, an aggregate of particles 91 is referred to as "powder to be treated."

[0013] A particle coating apparatus 1 according to this embodiment is composed of a powder layer forming unit 1A shown in FIG. 1 and a film forming unit 1B shown in FIG.

[0014] 1.1.Powder layer formation unit The powder layer forming unit 1A shown in FIG.

[0015] The powder supply section 13 has a front chamber 132 , a supply nozzle 133 , a front chamber heating section 134 , a front chamber exhaust section 135 , an upper gate valve 136 , and a lower gate valve 137 .

[0016] The anterior chamber 132 is a rigid, airtight container that contains the powder to be treated. The anterior chamber 132 maintains a reduced pressure state by evacuating the inside. Examples of materials that can be used to form the anterior chamber 132 include glass materials such as quartz glass, ceramic materials such as alumina, and metal materials such as stainless steel, aluminum, and titanium.

[0017] The supply nozzle 133 is a flow path connected to the lower end of the front chamber 132. The supply nozzle 133 turns the powder to be treated contained in the front chamber 132 into a thin stream and supplies it downward.

[0018] The front chamber heating section 134 heats the front chamber 132. Examples of the front chamber heating section 134 include a heater block, a film heater, a sheet heater, a sheath heater, and an infrared radiation heater.

[0019] The front chamber exhaust unit 135 exhausts the front chamber 132. The front chamber exhaust unit 135 includes, for example, a vacuum pump, a pressure gauge, piping, an opening and closing valve, and the like.

[0020] The powder to be treated is supplied to the front chamber 132 from the supply hopper 22. The supply hopper 22 is a portable container that contains the powder to be treated.

[0021] The upper gate valve 136 is provided at the upper end of the front chamber 132 and switches the supply of the powder to be treated from the supply hopper 22 provided above the front chamber 132 into the front chamber 132. By transferring the powder to be treated from the supply hopper 22 to the front chamber 132, the powder to be treated can be temporarily stored in an appropriate environment. The appropriate environment refers to an environment in which contact with the outside air is avoided and a predetermined temperature is maintained. In addition, the upper gate valve 136 only needs to have a degree of obstruction that can stop the supply of the powder to be treated when closed, but is preferably airtight. This makes it possible to prevent the powder to be treated contained in the front chamber 132 from coming into contact with the outside air, and suppresses the effects of oxygen, moisture, and the like on the powder to be treated.

[0022] The lower gate valve 137 is provided between the front chamber 132 and the supply nozzle 133, and has a function of switching the supply of the powder to be processed when the powder to be processed is supplied downward through the supply nozzle 133. This allows fine adjustment of the supply amount of the powder to be processed. The lower gate valve 137 only needs to have a degree of obstruction that allows the supply of the powder to be processed to be stopped when closed, but is preferably airtight. This makes it possible to prevent the powder to be processed contained in the front chamber 132 from coming into contact with the outside air, and suppresses the effects of oxygen, moisture, and the like on the powder to be processed.

[0023] The upper gate valve 136 and the lower gate valve 137 are each operated manually or electrically.

[0024] The powder layer forming section 3 has a tray conveying section 32 and a squeegee 30. The tray conveying section 32 conveys the tray 12 so that the powder to be processed supplied from the powder supplying section 13 is deposited on the tray 12. As shown in FIG. 1, the tray 12 is a container having a bottom plate 122 and a frame 123. The bottom plate 122 is in the form of a plate extending along the XY plane, and the frame 123 is in the form of a ring having a rectangular outer shape and is disposed on the surface of the bottom plate 122 on the positive side of the Z axis. The internal space defined by the bottom plate 122 and the frame 123 accommodates the powder to be processed. The tray conveying section 32 has a conveyor belt 33 and a conveyor roller 34. The conveyor belt 33 conveys the tray 12 placed thereon toward the positive side of the X axis. The conveyor roller 34 drives the conveyor belt 33. The squeegee 30 is disposed above the space through which the tray 12 passes. The powder to be processed piled up on the tray 12 is leveled by the squeegee 30 as it passes under the squeegee 30. As a result, a powder layer 90 in which the powder to be processed is spread in a layer along the XY plane is formed on the tray 12. The squeegee 30 has, for example, a plate shape that spreads along the YZ plane and extends elongated in the Y-axis direction.

[0025] Since the powder layer forming unit 3 as described above is disposed outside the processing chamber 11, the powder layer 90 can be formed without being restricted by space or workability. Therefore, the speed of forming the powder layer 90 can be easily increased.

[0026] The configuration of the powder layer forming unit 1A is not limited to the above. For example, the front chamber heating unit 134, the front chamber exhaust unit 135, the upper gate valve 136, the tray transport unit 32, and the like may be provided as needed, and may be omitted. The entire powder layer forming unit 1A may also be provided as needed, and may be replaced with another device capable of forming the powder layer 90.

[0027] 1.2. Film forming unit The film-forming unit 1B shown in FIG. 2 includes a processing chamber 11, a tray 12, a placement unit 19, a raw material gas supply unit 142, an oxidizing agent supply unit 144, a processing chamber exhaust unit 15, and a processing chamber heating unit 16. In the film-forming unit 1B, the powder to be processed (particles 91) is accommodated in the processing chamber 11, and the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, and then the raw material gas supply unit 142 and the oxidizing agent supply unit 144 introduce the raw material gas G1 and the oxidizing agent G2. In addition, the processing chamber heating unit 16 heats the powder to be processed. The raw material gas G1 introduced into the processing chamber 11 is decomposed, and the decomposition product is adsorbed on the surface of the particles 91 of the powder to be processed, and finally, a coating 92 shown in FIG. 3 is formed. As a result, the coated particles 93 shown in FIG. 3 are obtained. In the following description, the aggregate of the coated particles 93 is also called "treated powder."

[0028] The treatment chamber 11 is a rigid and airtight container in which the powder to be treated is accommodated and a coating 92 is formed on the surfaces of particles 91 of the powder to be treated. The treatment chamber 11 maintains a reduced pressure state by evacuating the inside. Examples of materials constituting the treatment chamber 11 include glass materials such as quartz glass, ceramic materials such as alumina, and metal materials such as stainless steel, aluminum, and titanium.

[0029] The processing chamber 11 shown in FIG. 2 has a chamber 112 having an opening 113, and an opening / closing part 114 which is a door for opening and closing the opening 113. When the opening / closing part 114 is closed, it airtightly blocks the opening 113. On the other hand, when the opening / closing part 114 is opened, it allows the tray 12 to pass through the opening 113. By providing such an opening / closing part 114, it is possible to efficiently carry the tray 12 into and out of the processing chamber 11. In addition, it is possible to carry the tray 12 into the processing chamber 11 while holding the powder layer 90. Therefore, it is also useful from the viewpoint of efficiently forming the powder layer 90 outside the processing chamber 11. As a result, it is possible to improve the efficiency of manufacturing the coated particles 93.

[0030] 2, the opening 113 is provided in a wall intersecting with the X-axis of the processing chamber 11, but the opening 113 may be provided in a wall intersecting with the Y-axis or a wall intersecting with the Z-axis. Also, a plurality of openings 113 may be provided.

[0031] A plurality of trays 12 are arranged in the processing chamber 11. The trays 12 hold the powder to be processed in a state of a powder layer 90 formed by spreading the powder in a layer shape. Holding means maintaining the relative positions of the particles 91 so as not to change, specifically, the powder layer 90 being left stationary. By arranging a plurality of trays 12, a large amount of powder to be processed can be provided for one film forming step. This can increase the production efficiency of the coated particles 93.

[0032] The size of the tray 12 is appropriately set depending on the size of the processing chamber 11, etc. As an example, the maximum possible length along the XY plane is preferably 100 mm or more and 2000 mm or less, and more preferably 200 mm or more and 1000 mm or less. The constituent material of the tray 12 is not particularly limited, and examples thereof include metal materials, resin materials, ceramic materials, glass materials, and carbon materials. The constituent material of the tray 12 may also be a composite material containing two or more of these materials.

[0033] The distance between the trays 12 is set appropriately depending on the size of the trays 12, and as an example, the minimum distance along the Z axis is preferably 10 mm or more, and more preferably 20 mm or more. This allows the source gas G1 and the oxidizing agent G2 to easily enter the gaps between the trays 12, and makes it easier to form the coating 92 with a uniform thickness. On the other hand, from the viewpoint of preventing the length of the processing chamber 11 in the Z axis direction from becoming longer than necessary, the upper limit of the minimum distance along the Z axis is preferably 1000 mm or less, and more preferably 500 mm or less.

[0034] The number of trays 12 accommodated in the processing chamber 11 is not particularly limited as long as it is more than one, but from the viewpoint of balancing productivity and the size of the processing chamber 11, it is preferable for the number to be three or more, and more preferably five or more and twenty or less.

[0035] In the processing chamber 11, a leg portion 116 and a mounting portion 19 are provided. The leg portion 116 extends from the bottom surface of the processing chamber 11 toward the positive side of the Z axis. A plurality of leg portions 116 are arranged at a predetermined interval on the bottom surface. A plurality of mounting portions 19 are attached to the leg portions 116 and arranged at a predetermined interval along the Z axis. Each mounting portion 19 is configured to support the tray 12 from below. Therefore, the plurality of mounting portions 19 support the plurality of trays 12 in a detachable state. The detachable state refers to a state in which the mounting portion 19 does not have a mechanism for restraining the tray 12, or a state in which the mounting portion 19 has a mechanism for arbitrarily switching between a restrained state and a non-restrained state.

[0036] Furthermore, in the processing chamber 11, a plurality of trays 12 are arranged side by side along the Z axis. With this configuration, a plurality of trays 12 can be arranged in a space-saving manner even in a processing chamber 11 having a small footprint. This allows the particle coating apparatus 1 to be space-saving while efficiently producing coated particles 93. Note that the configurations of the legs 116 and the mounting parts 19 are not limited to the configurations shown in the figure, as long as they are capable of supporting the trays 12. Furthermore, the number of mounting parts 19 is not particularly limited as long as there are multiple mounting parts, and is appropriately set depending on, for example, the size of the processing chamber 11, the size of the trays 12, etc.

[0037] A raw gas supply unit 142 and an oxidizing agent supply unit 144 are connected to the processing chamber 11. The raw gas supply unit 142 supplies the raw gas G1 required for forming the coating 92 into the processing chamber 11 and adjusts the partial pressure of the raw gas G1 in the processing chamber 11. The raw gas supply unit 142 includes, for example, a raw gas storage unit, a pipe, a flow rate control valve, and the like. The oxidizing agent supply unit 144 supplies the oxidizing agent G2 required for forming the coating 92 into the processing chamber 11 and adjusts the partial pressure of the oxidizing agent G2 in the processing chamber 11. The oxidizing agent supply unit 144 includes, for example, an oxidizing agent storage unit, a pipe, a flow rate control valve, and the like. Note that in FIG. 2, ozone O3 is illustrated as an example of the oxidizing agent G2. By using ozone as the oxidizing agent G2, the coating 92 that is denser and has a uniform thickness can be formed more efficiently. The source gas G1 and the oxidizing agent G2 are supplied, if necessary, together with a carrier gas mainly composed of an inert gas such as nitrogen gas or argon gas.

[0038] The processing chamber exhaust unit 15 exhausts the inside of the processing chamber 11. This makes it possible to reduce the pressure inside the processing chamber 11. The processing chamber exhaust unit 15 includes, for example, a vacuum pump, a pressure gauge, piping, an exhaust valve, and the like.

[0039] The processing chamber heating unit 16 heats the processing chamber 11, and thus heats the powder layer 90. Examples of the processing chamber heating unit 16 include a heater block, a film heater, a sheet heater, a sheath heater, and an infrared radiation heater. In FIG. 2, the processing chamber heating unit 16 is disposed outside the processing chamber 11, but the location of the processing chamber heating unit 16 is not limited thereto. The processing chamber heating unit 16 may be disposed inside the processing chamber 11, or may be built into a wall that constitutes the processing chamber 11. The processing chamber heating unit 16 may be provided as necessary, and may be omitted.

[0040] By providing such a processing chamber heating unit 16, the temperature of the powder layer 90, the temperature of the source gas G1, and the temperature of the oxidizing agent G2 can be optimized, so that a denser coating 92 with a uniform thickness can be formed more efficiently.

[0041] 2. Powder to be treated and powder already treated Next, the powder to be treated and the powder already treated will be described.

[0042] A coated particle 93 shown in FIG. 3 is one particle of the treated powder, and has a particle 91 of the powder to be treated and a coating 92 .

[0043] The constituent material of the particles 91 (constituent material of the powder to be processed) is not particularly limited, and examples thereof include metal materials, ceramic materials, glass materials, silicon materials, carbon materials, and resin materials. Among these, the constituent material of the particles 91 may be a soft magnetic metal material. When the particles 91 made of a soft magnetic metal material are used in a magnetic element such as an inductor, it is necessary to ensure insulation between the particles 91. By using the above-mentioned particle coating device 1, it is possible to form a coating 92 that is sufficiently thin in thickness and has a high coverage rate. This allows the formation of coated particles 93 that can improve the magnetic properties and insulating properties of the magnetic element. In addition, the coating 92 formed by the atomic layer deposition method is dense, and therefore contributes to the realization of coated particles 93 with high insulating properties, for example.

[0044] Examples of soft magnetic metal materials include Fe-Si alloys such as pure iron and silicon steel, Fe-Ni alloys such as permalloy, Fe-Co alloys such as permendur, Fe-Si-Al alloys such as sendust, Fe-Cr-Si alloys, and other Fe-based alloys, as well as various Ni-based alloys, various Co-based alloys, and various amorphous alloys. Among these, examples of amorphous alloys include Fe-based alloys such as Fe-Si-B, Fe-Si-BC, Fe-Si-B-Cr-C, Fe-Si-Cr, Fe-B, Fe-PC, Fe-Co-Si-B, Fe-Si-B-Nb, and Fe-Zr-B, Ni-based alloys such as Ni-Si-B and Ni-PB, and Co-based alloys such as Co-Si-B.

[0045] The average particle size D50 of the particles 91 is not particularly limited, but is preferably 0.1 μm or more and 50.0 μm or less, more preferably 0.5 μm or more and 10.0 μm or less, and even more preferably 1.0 μm or more and 3.5 μm or less. The average particle size D50 of the particles 91 is determined as the particle size at which the cumulative amount from the small diameter side becomes 50% in the cumulative particle size distribution on a volume basis obtained by a laser diffraction method.

[0046] 3. Particle coating method Next, a particle coating method according to an embodiment will be described. FIG. 4 is a process diagram showing the particle coating method according to the embodiment.

[0047] 4 includes a step S102 of supplying a powder to be treated, a step S104 of forming a powder layer, a step S106 of carrying in a tray, a step S108 of depositing a film, a step S110 of carrying out a tray, and a step S112 of collecting. Note that in the following description, a method using the above-described particle coating apparatus 1 will be described as an example, but the particle coating method according to the present invention may also be a method using an apparatus other than the particle coating apparatus 1.

[0048] 3.1. Supplying powder to be treated 1 is opened, and the powder to be processed is transferred from the supply hopper 22 into the anterior chamber 132. After a predetermined amount of the powder to be processed has been transferred, the upper gate valve 136 is closed.

[0049] Thereafter, the inside of the anterior chamber 132 may be evacuated and depressurized as necessary. The pressure inside the anterior chamber 132 is not particularly limited, but is preferably 10 kPa or less, and more preferably 1 kPa or less. This makes it possible to suppress the remaining oxygen and moisture inside the anterior chamber 132, and more reliably suppress oxidation and deterioration of the powder to be treated contained in the anterior chamber 132. It is not necessary to set a lower limit for the pressure inside the anterior chamber 132, but taking into consideration the increased cost of maintaining a reduced pressure state and the possibility that the effects of reducing the pressure may not be fully obtained, a lower limit of 1×10 -5Pa or more, and 1×10 -3 It is more preferable that the pressure is 100 Pa or more.

[0050] The powder to be treated contained in the anterior chamber 132 may be heated as necessary. The heating temperature of the powder to be treated is not particularly limited, but is preferably 30° C. or more and 500° C. or less, and more preferably 50° C. or more and 300° C. or less. This allows the powder to be sufficiently preheated. As a result, in the film-forming step S108 described below, the coating 92 can be formed with a more uniform film thickness.

[0051] Next, the lower gate valve 137 is opened, and a predetermined amount of the powder to be treated contained in the anterior chamber 132 is supplied downward.

[0052] 3.2. Powder layer formation step In the powder layer forming step S104, an empty tray 12 is set in the powder layer forming section 3 shown in Fig. 1. Then, while the tray 12 is moved by the tray conveying section 32, the powder to be processed (particles 91) supplied from the powder supplying section 13 is deposited on the tray 12. Next, the deposited powder to be processed is leveled into a layer by the squeegee 30 shown in Fig. 1. As a result, the powder layer 90 shown in Fig. 1 is formed.

[0053] The method for forming the powder layer 90 is not limited to the above method. For example, the powder layer 90 may be formed by leveling the powder to be treated by applying vibration or the like.

[0054] Furthermore, the powder layer 90 may be subjected to a pretreatment prior to the formation of the coating 92 described below. Examples of the pretreatment include ozone treatment, radical treatment, ultraviolet treatment, plasma treatment, corona treatment, drying treatment, and solvent treatment. The pretreatment may be performed in the antechamber 132.

[0055] 3.3. Tray loading step In the tray loading step S106, first, the opening / closing part 114 of the processing chamber 11 is opened. Then, the tray 12 holding the powder layer 90 is loaded into the processing chamber 11 through the opening 113 of the opening / closing part 114. That is, the tray 12 is loaded through the opening / closing part 114. By loading the entire tray 12, the arrangement of the powder layer 90 can be performed more easily than when the powder layer 90 is formed inside the processing chamber 11. The loaded tray 12 is supported by the loading part 19 shown in FIG. 2. As a result, a plurality of trays 12 are loaded in a state of being aligned vertically. As a result, many trays 12 can be loaded into the processing chamber 11 while avoiding an increase in the size of the processing chamber 11.

[0056] 3.4. Film formation step In the film forming step S108, a film 92 is formed by atomic layer deposition on the powder layer 90 in the processing chamber 11. The film 92 is formed, for example, as follows.

[0057] First, the opening / closing part 114 is closed. Next, the inside of the processing chamber 11 is evacuated and reduced in pressure. The pressure inside the processing chamber 11 before the introduction of the source gas G1 and the oxidizing agent G2 is not particularly limited, but is preferably 10 kPa or less, and more preferably 1 kPa or less. This makes it possible to suppress residual oxygen and moisture inside the processing chamber 11. In addition, the lower limit of the pressure inside the processing chamber 11 does not need to be particularly set, but considering the increase in the cost of maintaining a reduced pressure state and the possibility that the effects of reducing the pressure may not be fully obtained, it is preferable to set the lower limit to 1×10 -5 Pa or more, and 1×10 -3 It is more preferable that the pressure is 100 Pa or more.

[0058] Next, the powder to be treated contained in the treatment chamber 11 is heated. This heating may be performed so as to overlap in time with the formation of the coating 92 described below, or may be performed separately from the film formation, i.e., without overlapping in time. Furthermore, the heating of the powder to be treated may be performed as necessary, and may be omitted. Furthermore, the powder to be treated may be heated before evacuation, or may be heated while evacuation is being performed.

[0059] The heating temperature is not particularly limited, but is preferably 30° C. or more and 500° C. or less, and more preferably 50° C. or more and 300° C. or less. In particular, when the constituent material of the particles 91 is a material with low heat resistance such as a resin material, the heating temperature is preferably 30° C. or more and 150° C. or less, and more preferably 30° C. or more and 100° C. or less. The heating time at such a heating temperature is preferably 0.1 hours or more and 300 hours or less, more preferably 0.5 hours or more and 50 hours or less, and even more preferably 1 hour or more and 40 hours or less.

[0060] Next, the raw material gas G1 is introduced into the processing chamber 11 by the raw material gas supply unit 142. The introduced raw material gas G1 is adsorbed to the surface of the particles 91 of the powder to be processed. At this time, once the raw material gas G1 is adsorbed to the surface of the particles 91, it is difficult for it to be further adsorbed in multiple layers. This makes it possible to control the thickness of the coating 92 to be finally obtained with high precision. In addition, the raw material gas G1 also gets around and adsorbs into shaded and gap parts. Therefore, the thickness of the powder layer 90 shown in FIG. 1 is appropriately set according to the depth to which the raw material gas G1 can penetrate from the top surface of the leveled powder to be processed.

[0061] As an example, the thickness of the powder layer 90 is preferably 1 mm or more and 50 mm or less, more preferably 3 mm or more and 30 mm or less, and even more preferably 5 mm or more and 20 mm or less.

[0062] The source gas G1 may be, for example, a gas containing a precursor of the coating 92. Specifically, when forming a silicon oxide-based coating 92, examples of the source gas G1 include dimethylaminosilane, methylethylaminosilane, diethylaminosilane, trisdimethylaminosilane, bisdiethylaminosilane, and bistertiarybutylaminosilane.

[0063] Examples of the material of the coating 92 that is formed include, in addition to silicon oxide, oxides such as hafnium oxide, tantalum oxide, titanium oxide, and chromium oxide, and nitrides such as aluminum nitride, titanium nitride, and tantalum nitride.

[0064] Next, the source gas G1 in the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, and then an inert gas such as nitrogen or argon is introduced as necessary. This replaces the source gas G1. Although not shown, the inert gas can be introduced in the same manner as the introduction of the source gas G1 and the oxidizing agent G2.

[0065] Next, the inert gas in the processing chamber 11 is exhausted by the processing chamber exhaust unit 15, and then the oxidizing agent G2 is introduced into the processing chamber 11 by the oxidizing agent supply unit 144. Examples of the oxidizing agent G2 include ozone shown in FIG. 2, plasma oxygen, water vapor, and the like.

[0066] The oxidizing agent G2 reacts with the source gas G1 adsorbed on the surface of the particles 91 of the powder to be treated, forming a coating 92. Like the source gas G1, the oxidizing agent G2 also gets into the shaded areas and gaps. Therefore, the thickness of the powder layer 90 shown in FIG. 1 corresponds to the depth that the oxidizing agent G2 can penetrate from the top surface of the leveled powder to be treated.

[0067] Next, the oxidizing agent G2 in the processing chamber 11 is exhausted by the processing chamber exhaust part 15, and then an inert gas is introduced, if necessary, to replace the oxidizing agent G2. In this manner, the coating 92 is formed, and the coated particles 93 are obtained.

[0068] Depending on the target thickness of the coating 92, the introduction and discharge of the source gas G1 and the introduction and discharge of the oxidizing agent G2 may be repeated. The thickness of the coating 92 can be increased depending on the number of times the introduction and discharge are repeated. This makes it easy to obtain the desired thickness of the coating 92.

[0069] Thereafter, if necessary, post-treatment may be performed on the coated particles 93. Examples of the post-treatment include a charge removal treatment and a radical treatment.

[0070] Among these, the charge removal process is a process for reducing the amount of charge caused by the electrostatic charge of the coated particles 93. For example, an ionizer is used for the charge removal process.

[0071] The thickness of the coating 92 is not particularly limited, but is preferably 1 nm to 500 nm, more preferably 2 nm to 300 nm, and even more preferably 4 nm to 200 nm. Such a thickness allows the coating 92 to be formed uniformly in a relatively short time. Furthermore, the atomic layer deposition method allows the formation of a dense coating 92, so that even a thin coating of this thickness has sufficient insulating ability. In this case, the coating 92 has good insulating properties. The thickness of the coating 92 is the average value of measurements taken at five or more points by enlarging and observing the cross section of the coated particle 93.

[0072] The formation of the coating 92 as described above is performed while the powder layer 90 is left stationary. Therefore, the coating 92 can be formed with a uniform thickness.

[0073] 3.5. Tray removal step In the tray unloading step S110, the pressure inside the processing chamber 11 is returned to atmospheric pressure, and then the opening / closing part 114 is opened. Then, the tray 12 on which the coated particles 93 are laid in layers is unloaded through the opening 113 through which the opening / closing part 114 is opened. That is, the tray 12 is unloaded through the opening / closing part 114. By unloading the entire tray 12, the operation of unloading the coated particles 93 can be easily performed.

[0074] 3.6. Collection Step In the recovery step S112, the treated powder (coated particles 93) is recovered from the tray 12.

[0075] FIG. 5 is a schematic diagram showing a method for recovering coated particles 93 from tray 12 in recovery step S112.

[0076] Since the tray 12 is portable, it may be tilted on the recovery hopper 24 as shown in Fig. 5. This allows the coated particles 93 laid on the tray 12 to be easily transferred to the recovery hopper 24. In this manner, the treated powder can be recovered.

[0077] 4. Variations Next, a particle coating apparatus 1 according to a modified example of the above embodiment will be described.

[0078] 4.1. First modified example FIG. 6 is a cross-sectional view showing a film forming unit 1B included in the particle coating apparatus 1 according to the first modified example.

[0079] The first modified example will be described below, but in the following description, the differences from the above embodiment will be mainly described, and a description of similar points will be omitted.

[0080] The first modified example is similar to the above embodiment except that the arrangement of the trays 12 in the processing chamber 11 is different.

[0081] In the above embodiment, the placement unit 19 is configured so that the plurality of trays 12 are placed in a vertical line in the processing chamber 11. In contrast, the placement unit 19 shown in FIG. 6 is configured so that the trays 12 are placed in a horizontal line. With this configuration, the processing chamber 11 can be made low-profile. This allows the particle coating device 1 to be realized with excellent operability in loading and unloading the trays 12. In addition, since the trays 12 do not overlap each other when viewed from the thickness direction (Z-axis direction) of the powder layer 90, it is easy to ensure uniform contact between the source gas G1 and the oxidizing agent G2 and the powder to be processed. Therefore, the coating 92 can be formed with a more uniform film thickness. In the first modified example as described above, the same effects as those of the above embodiment can be obtained.

[0082] 4.2. Second variant FIG. 7 is a perspective view showing a squeegee 30 provided in the particle coating apparatus 1 according to the second modified example.

[0083] The second modified example will be described below, but in the following description, the differences from the above embodiment will be mainly described, and a description of similar points will be omitted.

[0084] The second modified example is similar to the above embodiment except that the shape of the squeegee 30 is different.

[0085] The squeegee 30 shown in Fig. 7 is in the form of a plate extending along the Y axis. As the powder passes under the squeegee 30 along the X axis, the powder is leveled and an upper surface of the powder is formed along the XY plane. As a result, a powder layer 90 having this upper surface is obtained.

[0086] The squeegee 30 shown in Fig. 7 has ridge lines 31. The shape of these ridge lines 31 is reflected on the upper surface of the powder layer 90. The ridge lines 31 shown in Fig. 7 are corrugated. Therefore, the upper surface of the powder layer 90 formed by the squeegee 30 is formed into a corrugated shape as shown in Fig. 7. Specifically, the upper surface of the powder layer 90 shown in Fig. 7 has a shape including ridges 901 or grooves 902 extending along the X-axis as a result of being smoothed by the squeegee 30.

[0087] By using a squeegee 30 having such wavy ridges 31, the surface area of ​​the upper surface of the powder layer 90 can be made larger than in the case of using a squeegee having straight ridges, for example. This allows the source gas G1 and the oxidizing agent G2 to penetrate deeper when forming the coating 92 on the powder layer 90. As a result, it is possible to increase the amount of treated powder that can be produced at one time and to increase the production speed of the treated powder.

[0088] The shape of the ridgeline 31 is not limited to the waveform shown in Fig. 7, and may be any shape that includes ridges 901 or grooves 902 when left on the top surface of the powder layer 90 by the squeegee 30. In other words, the ridgeline may not be a straight line, and may have any shape that includes some convex or concave portion. However, in order to make the permeation amount of the source gas G1 and the oxidizing agent G2 uniform, it is preferable that the shape be a repeating pattern as shown in Fig. 7. In addition, the powder layer 90 may have any shape that includes ridges 901 or grooves 902, but it is preferable that the powder layer 90 includes both of these in terms of increasing the surface area. In the second modified example as described above, the same effects as those of the above embodiment can be obtained.

[0089] 4.3.Third Modification FIG. 8 is a cross-sectional view showing a film forming unit 1B included in a particle coating apparatus 1 according to a third modified example.

[0090] The third modified example will be described below, but in the following description, the differences from the above embodiment will be mainly described, and a description of similar points will be omitted.

[0091] The third modified example is similar to the above embodiment, except that the oxidizing agent supply unit 144 includes an oxygen gas supply unit 146 and a plasma generation unit 148 shown in FIG.

[0092] The oxygen gas supply unit 146 supplies oxygen gas G3 required for generating plasma oxygen into the processing chamber 11, and adjusts the partial pressure of the oxygen gas G3 in the processing chamber 11. The oxygen gas supply unit 146 includes, for example, an oxygen gas storage unit, a pipe, a flow rate adjustment valve, and the like.

[0093] The plasma generating unit 148 has an upper electrode 148a, a lower electrode 148b, and a high frequency power supply 148c. The upper electrode 148a is disposed at the upper part of the processing chamber 11 and is connected to the high frequency power supply 148c. The lower electrode 148b is disposed at the lower part of the processing chamber 11 and is grounded.

[0094] Oxygen gas G3 is supplied into the processing chamber 11 by the oxygen gas supply unit 146, and in this state, the oxygen gas G3 is converted into plasma oxygen by the plasma generation unit 148. That is, plasma oxygen is generated in the processing chamber 11. As a result, the plasma oxygen generated in the processing chamber 11 can be used as the oxidizing agent G2. By using plasma oxygen as the oxidizing agent G2, the heating temperature when forming the coating 92 can be lowered. That is, it becomes possible to form the coating 92 at a lower temperature. As a result, even if the heat resistance of the constituent material of the particles 91 is low, it can be used to form the coating 92.

[0095] Alternatively, the lower electrode 148b may be connected to a high-frequency power source 148c, and the upper electrode 148a may be grounded.

[0096] Alternatively, the upper electrode 148a and the lower electrode 148b may both be connected to the high frequency power supply 148c so that they have opposite polarities. In this case, the generated plasma oxygen can be drawn to the lower electrode 148b side. This allows the plasma oxygen as the oxidizer G2 to penetrate deeper into the powder layer 90. As a result, the amount of treated powder that can be produced at one time can be increased, and the production efficiency of the treated powder can be improved. In the third modified example as described above, the same effects as those of the above embodiment can be obtained.

[0097] 4.4. Fourth Modification FIG. 9 is a cross-sectional view showing a tray 12 included in a particle-coating apparatus 1 according to a fourth modified example.

[0098] The fourth modified example will be described below, but in the following description, the differences from the above embodiment will be mainly described, and a description of similar points will be omitted.

[0099] The fourth modified example is similar to the above embodiment except that the configuration of the tray 12 is different. 9 includes a bottom plate 122 having a plurality of through holes 124, and a frame 123 provided on one surface of the bottom plate 122. The through holes 124 penetrate the bottom plate 122. Therefore, when the tray 12 holds the powder layer 90, the source gas G1 and the oxidizing agent G2 can permeate the powder layer 90 not only from above but also from below. As a result, it is possible to increase the amount of treated powder that can be produced at one time and to increase the production speed of the treated powder.

[0100] Examples of the bottom plate 122 having the through-holes 124 include mesh, punched metal, fabric, and porous material. For example, in the case of a mesh or fabric, the openings correspond to the through-holes 124. In the case of a porous material, the communicating holes contained therein correspond to the through-holes 124.

[0101] The inner diameter of the through hole 124 is set appropriately according to the outer diameter of the particles 91 of the powder to be treated, and may be equal to or larger than the outer diameter, but is preferably smaller than the outer diameter. In the fourth modified example as described above, the same effects as those of the above embodiment can be obtained.

[0102] 5. Effects of the above embodiment or the above modification As described above, the particle coating apparatus 1 according to the embodiment or the modified example is an apparatus for forming a coating 92 on the surface of a particle 91 of a powder to be treated by atomic layer deposition, and includes a processing chamber 11, a raw material gas supply unit 142, an oxidizing agent supply unit 144, a processing chamber exhaust unit 15, a plurality of trays 12, and a mounting unit 19. The processing chamber 11 has a chamber 112 and an opening / closing unit 114 for opening and closing the chamber 112. The raw material gas supply unit 142 supplies a raw material gas G1 into the processing chamber 11. The oxidizing agent supply unit 144 supplies an oxidizing agent G2 into the processing chamber 11. The processing chamber exhaust unit 15 exhausts the inside of the processing chamber 11. The plurality of trays 12 can be carried into the processing chamber 11 via the opening / closing unit 114, and hold a powder layer 90 in which the powder to be treated is laid in layers. The mounting unit 19 is disposed in the processing chamber 11, and the plurality of trays 12 are mounted thereon in a detachable state.

[0103] According to this configuration, the powder layer 90 is left stationary while the coating 92 is formed, so that the coating 92 can be formed with a uniform thickness. In addition, since an opening / closing section 114 is provided that allows the tray 12 holding the powder layer 90 to be brought into the processing chamber 11, the powder layer 90 can be formed outside the processing chamber 11, and as a result, the efficiency of manufacturing the coated particles 93 can be improved. Furthermore, since the processing chamber 11 is provided with a mounting section 19 that allows a plurality of trays 12 to be mounted thereon, a large amount of powder to be processed can be provided for one coating. Thus, according to the above configuration, a particle coating device 1 can be obtained that can efficiently manufacture particles 91 coated with a thin coating 92 with a uniform thickness, i.e., coated particles 93.

[0104] Furthermore, the placement section 19 may be configured so that a plurality of trays 12 are placed thereon in a vertical line.

[0105] According to this configuration, a plurality of trays 12 can be arranged in a small space even in a processing chamber 11 having a small footprint, thereby enabling the coated particles 93 to be produced more efficiently.

[0106] Furthermore, the placement section 19 may be configured so that a plurality of trays 12 are placed thereon in a horizontal line.

[0107] According to this configuration, the processing chamber 11 can be made low-profile. This allows the particle coating apparatus 1 to be realized with excellent operability in loading and unloading the trays 12. In addition, since the trays 12 do not overlap each other, it is easy to ensure uniform contact between the source gas G1 and the oxidizing agent G2 and the powder to be processed. This allows the coating 92 to be formed with a more uniform thickness.

[0108] The particle coating apparatus 1 may further include a powder supplying unit 13 and a powder layer forming unit 3. The powder supplying unit 13 is disposed outside the processing chamber 11, stores the powder to be processed, and supplies a predetermined amount of the powder to be processed. The powder layer forming unit 3 is disposed outside the processing chamber 11, and deposits the powder to be processed supplied from the powder supplying unit 13 on the tray 12 to form a powder layer 90.

[0109] According to this configuration, since the powder layer forming part 3 is disposed outside the processing chamber 11, the powder layer 90 can be formed without being restricted by space or workability. Therefore, the speed of forming the powder layer 90 can be easily increased.

[0110] The powder layer forming unit 3 may also have a squeegee 30. The squeegee 30 levels the powder to be processed that has accumulated on the tray 12. The squeegee 30 has a ridge 31 that comes into contact with the powder to be processed when the powder to be processed is leveled. The ridge 31 is configured so that the shape left on the surface of the powder to be processed leveled by the squeegee 30 includes a convex ridge 901 or a groove 902.

[0111] With this configuration, the surface area of ​​the upper surface of the powder layer 90 can be made larger than when a squeegee with straight ridges is used. This allows the source gas G1 and the oxidizing agent G2 to penetrate deeper when forming the coating 92 on the powder layer 90. As a result, it is possible to increase the amount of treated powder that can be produced at one time and to increase the production speed of the treated powder.

[0112] Alternatively, the oxidizing agent G2 may be ozone. In this case, the particle coating apparatus 1 may further include a processing chamber heating unit 16. The processing chamber heating unit 16 heats the powder layer 90.

[0113] According to this configuration, a denser coating 92 with a uniform thickness can be formed more efficiently.

[0114] The oxidizing agent G2 may be plasma oxygen. In this case, the oxidizing agent supply unit 144 may include an oxygen gas supply unit 146 and a plasma generation unit 148. The oxygen gas supply unit 146 supplies oxygen gas G3 into the processing chamber 11. The plasma generation unit 148 changes the oxygen gas G3 into plasma oxygen.

[0115] According to this configuration, the generated plasma oxygen can be used as the oxidizing agent G2, which allows the heating temperature to be lowered when forming the coating 92. In other words, the coating can be formed at a lower temperature. This allows the coating 92 to be formed even if the material of the particles 91 has low heat resistance.

[0116] Moreover, the tray 12 may include a bottom plate 122 having a through hole 124 and a frame 123 provided on one surface of the bottom plate 122 .

[0117] According to this configuration, when the tray 12 holds the powder layer 90, the source gas G1 and the oxidizing agent G2 can permeate not only from above but also from below the powder layer 90. As a result, it is possible to increase the amount of treated powder that can be produced at one time and to increase the production speed of the treated powder.

[0118] The particle coating method according to the embodiment or the modified example is a method for forming a coating 92 on the surface of a particle 91 of a powder to be treated by atomic layer deposition, and includes a tray carrying step S106, a film forming step S108, and a tray carrying step S110. In the tray carrying step S106, a plurality of trays 12 holding a powder layer 90 formed by laying the powder to be treated in layers are carried into the processing chamber 11 via the opening / closing part 114. In the film forming step S108, after the opening / closing part 114 is closed, the coating 92 is formed on the powder layer 90 in the processing chamber 11 by the atomic layer deposition method. In the tray carrying step S110, the opening / closing part 114 is opened, and the plurality of trays 12 holding the powder layer 90 after the coating 92 is formed are carried out from the processing chamber 11.

[0119] According to such a configuration, the powder layer 90 is left stationary while the coating 92 is being formed, so that the coating 92 can be formed with a uniform thickness.

[0120] The powder to be treated may be made of a soft magnetic metal material, and the coating 92 may be made of an insulating material.

[0121] According to such a configuration, it is possible to form coating 92 that is sufficiently thin, dense, and has a high coverage rate, thereby obtaining coated particles 93 that can realize a magnetic element having excellent magnetic properties and insulating properties.

[0122] Although the particle coating apparatus and the particle coating method according to the present invention have been described based on the illustrated embodiments, the present invention is not limited to these.

[0123] For example, the particle coating apparatus according to the present invention may be one in which each part of the above embodiment is replaced with any component having the same function, or any component may be added to the above embodiment. Also, the particle coating method according to the present invention may be one in which any purposed step is added to the above embodiment. [Explanation of symbols]

[0124] 1...particle coating device, 1A...powder layer forming unit, 1B...film forming unit, 3...powder layer forming section, 11...treatment chamber, 12...tray, 13...powder supply section, 15...treatment chamber exhaust section, 16...treatment chamber heating section, 19...mounting section, 22...supply hopper, 24...recovery hopper, 30...squeegee, 31...ridge line, 32...tray transport section, 33...conveyor belt, 34...conveyor roller, 90...powder layer, 91...particle, 92...coating, 93...coated particle, 112...chamber, 113...opening, 114...opening / closing section, 116...leg, 122...bottom plate, 123...frame, 124...through hole, 132...antechamber, 13 3...supply nozzle, 134...pre-chamber heating section, 135...pre-chamber exhaust section, 136...upper gate valve, 137...lower gate valve, 142...source gas supply section, 144...oxidizer supply section, 146...oxygen gas supply section, 148...plasma generation section, 148a...upper electrode, 148b...lower electrode, 148c...high frequency power source, 901...ridge, 902...groove, G1...source gas, G2...oxidizer, G3...oxygen gas, S102...processed powder supply step, S104...powder layer formation step, S106...tray loading step, S108...film formation step, S110...tray unloading step, S112...recovery step

Claims

1. A particle coating apparatus for forming a coating on a surface of a powder to be treated by an atomic layer deposition method, a processing chamber having a chamber and an opening / closing part for opening and closing the chamber; a raw material gas supply unit for supplying a raw material gas into the processing chamber; an oxidant supply unit for supplying an oxidant into the processing chamber; a processing chamber exhaust unit that exhausts the inside of the processing chamber; a plurality of trays that can be carried into the treatment chamber through the opening and closing part and hold a powder layer in which the powder to be treated is laid in layers; a placement unit disposed within the processing chamber, on which the plurality of trays are detachably placed; A particle coating apparatus comprising:

2. 2. The particle coating apparatus according to claim 1, wherein the placement section is configured so that a plurality of the trays are placed on the placement section in a vertical direction.

3. 2. The particle coating apparatus according to claim 1, wherein the placement section is configured so that a plurality of the trays are placed on the placement section in a horizontal direction.

4. a powder supply unit disposed outside the processing chamber, which stores the powder to be processed and supplies a predetermined amount of the powder to be processed; a powder layer forming unit that is disposed outside the processing chamber and deposits the powder to be processed supplied from the powder supply unit onto the tray to form the powder layer; The particle coating apparatus according to claim 1 , further comprising:

5. The powder layer forming unit has a squeegee for leveling the powder to be processed deposited on the tray, the squeegee has a ridge that comes into contact with the powder to be treated when the powder is leveled, 5. The particle coating apparatus according to claim 4, wherein the ridge lines are configured so that a shape left on the surface of the treated powder smoothed by the squeegee includes a ridge or a groove.

6. the oxidizing agent is ozone; 4. The particle coating apparatus according to claim 1, further comprising a processing chamber heating section for heating the powder layer.

7. the oxidant is plasma oxygen; The oxidant supply unit is an oxygen gas supply unit for supplying oxygen gas into the processing chamber; a plasma generating unit that converts the oxygen gas into the plasma oxygen; The particle coating apparatus according to claim 1 , further comprising:

8. 4. The particle coating apparatus according to claim 1, wherein the tray comprises a bottom plate having a through hole and a frame provided on one surface of the bottom plate.

9. A particle coating method for forming a coating on a surface of a powder to be treated by atomic layer deposition, comprising the steps of: carrying a plurality of trays holding powder layers in which the powder to be processed is laid in layers into the processing chamber via an opening / closing section; After closing the opening and closing part, forming the coating on the powder layer by an atomic layer deposition method in the processing chamber; opening the opening / closing portion, and carrying out the trays holding the powder layer after the coating is formed from outside the processing chamber; A particle coating method comprising the steps of:

10. The powder to be treated is made of a soft magnetic metal material, 10. The method for coating particles according to claim 9, wherein the coating is made of an insulating material.

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