JP2001247907A - Manufacturing method and manufacturing apparatus of spherical metal particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method and a manufacturing apparatus of spherical metal particles in which spherical metal particles are obtained in a step that a metal stock piece or a liquid metal droplet is added in a container filled with a solution and dropped in the solution so that neither shrinkage cavity nor mirror ball-like defect is generated, and the shape of the manufactured metal particles is consistent. SOLUTION: In the manufacturing method and manufacturing apparatus of spherical metal particles in which the metal stock piece or the like is melted and cooled and solidified to manufacture the spherical metal particles 6 in the step that the metal stock piece 4 or the liquid metal droplet 5 is added into the container 1 filled with a heated solution 2, and dropped in the solution 2, the metal stock piece or the like is allowed to slide down along an inclined sliding-down surface 3 of the container 1. In addition, at least two sliding-down surfaces 3 are provided to allow the metal stock piece 4 or the liquid metal droplet 5 to slide down along each sliding-down surface 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing fine spherical metal particles, and in particular, to a BG.
The present invention relates to a method and an apparatus for producing spherical metal particles such as solder balls having a diameter of 100 μm to 1 mm to be used for electrical connection materials such as A, CSP, and connector contacts.

[0002]

2. Description of the Related Art In recent years, surface mounting of electronic circuit components has been steadily reduced in size and high-density mounting of electronic components. Along with this, the solder bonding technology used for bonding has been required to have higher functionality. In recent years, BGA (ball grid array) and CSP (chip size package) technologies have been expected as high-density mounting technologies. It is.
In these techniques, a fine solder ball is prepared, and the solder ball is formed on a target electrode by reflowing the solder ball. Also, recently, when arranging a connector on a substrate, a solder ball has been used for joining the substrate electrode and the connector electrode.

As a method for producing spherical low-melting metal particles typified by the above-mentioned fine solder balls, a metal element or a metal droplet is dropped in a liquid, and the metal is formed into a sphere during the dropping process. Methods for obtaining metal particles are known.

In the method of adding metal fragments, the upper part of the liquid filled in the container is kept at a high temperature above the melting point of the metal, and the lower part of the liquid is kept at a low temperature below the melting point of the metal. When an amorphous metal piece adjusted to a predetermined mass is added to a liquid and dropped in the liquid, an oxide film on the surface of the metal piece is first removed by a reducing solution. Next, the metal piece is melted in the high temperature part of the solution, and the metal droplet becomes spherical based on the interfacial tension between the metal droplet and the solution. Furthermore, when it falls in the solution and reaches the low temperature part, it solidifies while maintaining the spherical shape, and spherical metal particles can be obtained.

In the method of adding a metal droplet, a metal is melted, cut out as a droplet having a predetermined mass, and added to a solution. The metal droplets become spherical in the solution.
The temperature of the solution is maintained at a temperature not higher than the melting point of the metal at least in the lower part of the solution, and the added droplets solidify while maintaining the sphere in the process of descending in the solution, whereby spherical metal particles can be obtained.

For example, in a method of manufacturing a solder ball having a diameter of about 760 μm, a diameter of about 50 mm and a height of 1
A heat-resistant container of about m is prepared, and the container is filled with a solution having a boiling point higher than the melting point of the solder, for example, vegetable oil or silicone oil. In the method of adding the solder pieces, the temperature of the solution at the upper portion of the container is maintained at a temperature higher than the melting point of the solder, and the temperature of the solution at the lower portion of the container is maintained at a temperature lower than the melting point of the solder. The solder pieces cut out to a constant mass and added to the solution fall in the container while melting and spheroidizing in the solution,
Solidifies at the bottom of the container to form solder balls. By collecting the solder balls, spherical solder balls can be obtained.

[0007]

As the spherical metal droplets fall in the solution, the temperature of the solution through which the metal droplets pass decreases, and the metal droplets solidify into spherical metal particles. At this time, if the cooling rate of the metal droplet is too high, a so-called shrinkage cavity in which a part of the surface of the generated metal particle is depressed may be generated, which may be a defect. Conversely, if the cooling rate of the metal droplet is too low, the surface of the metal particle is overreduced and becomes polyhedral (a so-called mirror ball or dimple), which is also a defect. Therefore, the temperature gradient of the solution in the container is adjusted in consideration of the falling speed of the metal droplet in order to optimize the cooling speed of the metal droplet falling in the solution and prevent the above-mentioned defects from occurring. As a result, spherical metal grains are produced under the condition that neither shrinkage cavities nor mirror ball defects are generated.

However, in the process of producing spherical metal particles under the same conditions, metal particles having shrinkage cavities and metal particles having mirror ball-shaped defects may be present simultaneously in the same lot. In such a case, it has been difficult to eliminate both defects simultaneously even if the temperature gradient of the solution is changed. And, since the metal particles having these defects are simultaneously mixed in the product, it is not possible to sort out only the defective product, and it is necessary to treat the entire lot of the lot including the defective product as a defective product. The problem is that the rate becomes extremely high.

In addition, even within the same production lot, there has been a problem that the shape of the produced metal particles is not stable, and metal particles of uniform quality cannot be produced.

When manufacturing solder balls as metal particles, the diameter of the solder balls is 150 μm depending on the application.
m to 1000 μm. Since the falling speed of metal particles in a solution is proportional to the cube of its diameter, if one tries to keep the cooling rate of a metal piece or the like falling in a solution constant, the height of each metal particle to be manufactured has a different height. It is necessary to prepare many different types of containers.

The present invention relates to a method and an apparatus for producing spherical metal particles, in which metal fragments or metal droplets are added to a container filled with a solution and spherical metal particles are obtained in the process of falling into the solution. It is an object of the present invention to provide a method and an apparatus for producing spherical metal particles, which do not generate any nest defect or mirror ball defect and can stabilize the shape of the produced metal particles.

[0012] The present invention also provides a method for producing spherical metal particles capable of appropriately producing metal particles of any diameter without preparing various types of containers even when the diameter range of the metal particles to be produced is wide. It is an object to provide a method and an apparatus.

[0013]

A metal element or a metal droplet (hereinafter referred to as "metal element or the like") which falls vertically in a solution in a container is uniformly formed in a cross section (horizontal cross section) of the container. Although it is preferable to disperse, the density of the metal piece or the like falling on a specific portion in the cross section may be high, and the density of the metal piece or the like in other portions in the cross section may be low. At a portion where a large amount of metal pieces or the like fall at a high density, the solution is dragged by the metal pieces or the like, and a downward flow is generated in the solution. When a downflow occurs at a specific portion in the cross section, an upflow occurs at other portions in the cross section.

Naturally, there is a difference in the cooling rate in the process of falling through the solution between a metal piece or the like falling with the downward flow and a metal piece or the like falling against the upward flow. Further, when a downward flow or the like occurs in the solution, temperature unevenness occurs in the solution in the same cross section of the container, making it difficult to control the temperature of the cooling zone, or as a result, the temperature control becomes meaningless. Then, it has been clarified that when the drift is generated in the solution as described above, a high proportion of manufactured metal particles having shrinkage cavities and mirror ball-shaped defects coexist.

Further, as a result of the difference in the cooling rate for each metal piece and the like as described above, it was also found that the shape of the resulting metal particles was not stable, and metal particles of constant quality could not be produced.

The present invention has been made based on the above findings, and the gist thereof is as follows. (1) A metal element 4 is added to a container 1 filled with a heating solution 2 having a reducing action, and the metal element 4 is melted and cooled and solidified in the process of falling in the solution 2 to form spherical metal particles. A method for producing spherical metal particles, characterized in that a metal piece (4) is slid down along an inclined sliding surface (3) of a container (1). (2) Metal droplet 5 melted in container 1 filled with solution 2
In a method of manufacturing spherical metal particles by cooling and solidifying the metal droplets 5 in the process of dropping in the solution 2, the metal droplets 5 slide down along the inclined sliding surface 3 of the container 1. A method for producing spherical metal particles. (3) The spherical metal particles according to (1) or (2), wherein the sliding speed of the metal piece 4 or the metal droplet 5 is adjusted by adjusting the inclination angle θ of the sliding surface 3. Method. (4) The method for producing spherical metal particles according to (3), wherein the inclination angle θ of the sliding surface 3 is set to 15 to 75 degrees. (5) The method according to any one of the above (1) to (4), wherein two or more sliding surfaces 3 are provided, and the metal piece 4 or the metal droplet 5 is caused to slide down along each sliding surface 3. Manufacturing method of spherical metal particles. (6) The container 1 includes a container 1 for filling the solution 2 having a reducing action, a heating device 7 for heating the solution 2 in the container 1, and an adding device 10 for adding the metal piece 4 in the container 1. In a device for manufacturing a spherical metal particle by adding a metal element 4 to the inside and melting and cooling and solidifying the metal element 4 in the process of falling in the solution 2, the container 1 slides down the metal element 4. A spherical metal grain producing apparatus, characterized in that the apparatus has an inclined slide surface 3 for use. (7) Container 1 filled with solution 2 and metal droplet 5 in container 1
And a dropping device 11 for dropping a metal droplet 5 into the container 1, and cooling and solidifying the metal droplet 5 in the process of falling in the solution 2 to produce spherical metal particles. And a container 1 having an inclined sliding surface 3 for sliding a metal droplet 5 down. (8) The inclination angle θ of the sliding surface 3 is adjustable, and the sliding speed of the metal piece 4 or the metal droplet 5 is adjusted by adjusting the inclination angle θ of the sliding surface 3. 6) or the apparatus for producing spherical metal particles according to (7). (9) The apparatus for producing spherical metal particles according to (8), wherein the inclination angle θ of the sliding surface 3 can be adjusted within a range of 15 degrees to 75 degrees. (10) The method according to any one of the above (6) to (9), wherein two or more sliding surfaces 3 are provided, and the metal piece 4 or the metal droplet 5 is caused to slide down along each sliding surface 3. Spherical metal grain production equipment.

In the case where metal pieces and the like are added to a vertically arranged container and dropped, no matter how much the metal pieces and the like are added uniformly in the horizontal section of the container, unevenness in density occurs. It is difficult to avoid this, and as a result, in the conventional method, the quality of the metal particles to be manufactured varies.

On the other hand, in the present invention, the container 1 has an inclined sliding surface 3. Most commonly, as shown in FIGS.
Is referred to as a sliding surface 3. By inclining the container 1 with respect to the vertical, the wall surface located on the lower surface side among the wall surfaces of the container becomes the sliding surface 3.

The metal pieces and the like added into the container descend vertically and reach the sliding surface 3, and thereafter fall along the sliding surface 3 in the vicinity of the sliding surface 3, thereby causing the sliding of the container cross section. The metal pieces and the like are not distributed in portions other than the vicinity of the surface. As a matter of course, in the vicinity of the sliding surface, a downward flow of the solution occurs due to being dragged by a metal piece or the like,
As all the metal pieces fall with this descending flow,
There is no difference in cooling rate for each metal piece or the like. Therefore, it is possible to manufacture metal grains without any defect by selecting an appropriate cooling condition that does not cause shrinkage cavities or mirror ball defects as the cooling rate condition.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is preferable that the shape of the sliding surface 3 is flat. By making it a plane,
It is possible to slide down the metal piece or the like at a uniform density over the entire width of the sliding surface 3 in the horizontal direction. If the sliding surface has an arc shape such as a gutter, for example, the metal pieces gather on the bottom surface of the arc, so that the metal pieces cannot be distributed over the entire width of the sliding surface.

If the container 1 that fills the solution 2 has a rectangular cross-sectional shape and the container 1 is arranged to be inclined with respect to the vertical, the lower wall surface of the container 1 will be the sliding surface 3. (FIGS. 1 and 2). On the other hand, a plate for forming the sliding surface 3 may be provided in the container separately from the container wall surface instead of the sliding surface of the container.

The diameter of the metal grains produced by the present invention, particularly the diameter of the solder balls, ranges from 150 μm to 1000 μm. Since the vertical descent speed of a metal fragment or the like in a solution is proportional to the cube of the diameter, in a conventional method of vertically dipping in a container, the descent speed varies greatly depending on the diameter of the metal particles to be produced. In order to make the cooling rate during the descent constant, it is necessary to greatly vary the vertical temperature gradient of the solution in the container for each diameter of the metal particles. Therefore, it is necessary to prepare various kinds of containers having different heights for each diameter of the metal particles and various kinds of solution heating devices.

In the present invention, the inclination angle θ of the sliding surface 3
By adjusting the sliding speed, the sliding speed of a metal piece or the like can be adjusted. Therefore, when manufacturing a metal grain having a large diameter, the inclination angle θ (the angle with respect to the horizontal) of the sliding surface 3 is reduced, and the diameter is reduced. In the case of producing metal particles, if the inclination angle θ of the sliding surface 3 is increased, the sliding speed can be kept constant regardless of the diameter of the metal particles. Therefore, even when the range of the diameter of the metal particles to be manufactured is wide, the inclination of the sliding surface 3 is maintained without preparing a variety of containers and keeping the solution temperature gradient in the sliding direction of the metal piece or the like almost constant. Only by changing the angle θ, it becomes possible to produce metal grains having different diameters.

In the conventional method of vertically dropping a metal element or the like in a container, the rate of falling of the metal element or the like is fixed depending on the size of the generated metal particles. Therefore, it is necessary to control the cooling rate of the metal piece and the like during the descent by adjusting the temperature gradient in the vertical direction of the solution. In the present invention, even if the size of the metal particles is constant, the sliding speed of the metal piece or the like can be arbitrarily adjusted by adjusting the inclination angle θ of the sliding surface 3. Therefore,
By adjusting both the temperature gradient of the solution and the inclination angle of the sliding surface, it is possible to adjust the cooling rate of the metal pieces and the like in the solution to an optimum value.

The optimum inclination angle θ of the sliding surface can be selected based on the items described above. On the other hand, if the inclination angle θ exceeds 75 degrees, there is a metal piece or the like that falls in the liquid away from the slide surface without sliding down in the vicinity of the slide surface, so that a constant falling speed cannot be realized. . If the inclination angle θ is less than 15 degrees, the metal piece or the like does not slide down at a constant speed, and the metal piece or the like that stops temporarily is generated. Therefore, the inclination angle θ of the slide surface is 15 degrees or more,
It is preferable that the angle be 75 degrees or less.

When the method of the present invention is applied to the manufacture of solder balls, the length of the container 1 for filling the solution 2 is about 1 m, and when vegetable oil is used as the solution, the diameter is 760 μm.
In the production of the solder ball, the optimal inclination angle of the sliding surface 3 was 30 degrees, and in the production of a solder ball having a diameter of 300 μm, the optimal inclination angle was 60 degrees. In the production of a solder ball having a diameter of 150 μm, since the falling speed is slow even in the case of vertical drop, the optimum production condition was when the length of the container was 0.5 m and the inclination angle of the sliding surface 3 was 70 degrees. .

In the present invention, since the metal piece slides down along the inclined sliding surface, there is a concern that metal particles generated by sliding down the rotating sliding surface 3 may be deformed into an elliptical shape. However, when the sphericity of the produced metal particles was measured, the ratio between the diameter of the largest diameter part (longer diameter) and the diameter of the smallest diameter part (shorter diameter) was:
It was within the range of ± 10%, and it was confirmed that good sphericity within the allowable range was realized.

Compared with the conventional method of dropping a metal piece or the like using the entire cross section in the container, in the present invention, the metal piece or the like is slid down along the vicinity of the slide surface 3. The density of metal pieces and the like in the unit volume of the solution increases. If the density of the metal fragments and the like in the solution is too high, the droplets are welded to each other to form large droplets, and the diameter of the generated metal particles is not constant. It must be kept below a certain level. When one wall surface of the container 1 is used as the sliding surface 3, in order to keep the density of the metal pieces and the like on the sliding surface 3 within the above-mentioned appropriate range, it is necessary to limit the addition density of the metal pieces and the like. As a result, the productivity of metal particles is lower than that of the conventional method.

In the present invention, by arranging a plurality of sliding surfaces 3 in the container 1 and sliding metal pieces etc. along each sliding surface, the present invention can be implemented without reducing the productivity of metal particles. can do. Specifically, as shown in FIG. 3, a number of sliding surfaces (3a to 3e) are arranged in parallel in the container. For example, by arranging 16 layers of sliding surfaces at a pitch of 5 mm in a container having a rectangular cross section of 80 mm × 80 mm, the productivity can be reduced by 16 as compared with the case where one wall surface of the container is simply used as the sliding surface. Can be doubled. Thereby, productivity equivalent to the conventional method of vertically dropping a metal piece or the like in a container having a diameter of 100 mm can be secured.

The method and apparatus according to the present invention in the case where a metal piece is added to a container will be described with reference to FIG. In order to reduce the variation in the diameter of the generated metal particles to produce the metal particles having a constant diameter, it is necessary to reduce the variation in the mass of the metal pieces added into the container. A thin plate made of rolled metal or a wire drawn by metal is trimmed to a certain length,
By adopting a method of dropping into a container with the parts feeder 10 or a method of using a wire cutter for continuously cutting a wire to a fixed length, a metal piece having a uniform mass can be added to the container.

In the vessel 1, the temperature of the solution 2 at the top of the vessel 1 is maintained at a temperature higher than the melting point of the metal, and the added metal piece 4 is melted. The molten metal pieces are formed into droplets by the interfacial tension between the metal and the solution. By setting the solution temperature in the lower part of the container to a temperature lower than the melting point of the metal, the temperature decreases as the metal droplet 5 slides down the sliding surface 3, and solidified spherical metal particles 6 are deposited in the lower part of the container. The valve 9 is arranged at the lower part of the container, and the metal particles 6 deposited at the lower part of the container are collected by opening the valve 9.

As the solution 2, it is necessary to select a solution having a boiling point higher than the melting point of the metal and having a high interfacial tension with the metal. In the case of manufacturing solder balls, it is preferable to use silicone oil, vegetable oil, or the like as the solution 2.

Further, for example, when using solder as a metal, since the surface of the solder piece to be added is covered with an oxide film, it is necessary to remove the oxide film in the process of forming droplets.
This is because good spheroidization cannot be obtained with the oxide film attached. A substance having a reducing action for removing an oxide film is called a flux. By disposing the liquid flux at the top of the solution in the container, it becomes possible to remove the oxide film when the metal piece passes through the liquid flux layer. It is also preferable to provide the solution itself to be filled in the container with a reducing ability. For example, a method of diluting a commercially available flux liquid with a liquid such as silicone oil or a method of using a vegetable oil containing an unsaturated fatty acid known to have a reducing action, that is, a flux property, alone as a liquid is preferable.

In order to heat the temperature of the solution 2 in the upper part of the container above the melting point of the metal and maintain the temperature of the liquid in the lower part of the container below the melting point of the metal, a heating device is provided so as to surround the container 1 in the upper part of the container. It is preferable to dispose the cooling device 8 so as to surround the container 1 at the lower part of the container.

The method and apparatus according to the present invention when the molten metal droplet 5 is dropped into the solution will be described with reference to FIG. A metal, for example, a solder is heated and melted in a stainless steel cylindrical container 11 disposed above the container 1 to form a molten metal 13.
And A plurality of drip holes 12 are provided at the bottom of the cylindrical container 11, and the stainless steel plate at the bottom of the cylindrical container 11 is vibrated by applying ultrasonic waves or the like to thereby hold the solder droplets at a constant mass from the drip holes 12. Is dropped.

The metal droplet 5, for example, a solder droplet is added to the solution in the container, and cooled and solidified while maintaining the spherical shape.
Collected as spherical metal particles 6 in the lower part of the container. Since the droplet immediately after falling into the container is deformed by the impact of the collision with the solution surface, it is necessary to maintain a molten state until the droplet returns to a spherical shape due to the interfacial tension between the metal and the solution. Therefore, it is preferable that the uppermost temperature of the solution in the container is heated to a temperature higher than the melting point of the metal, or a temperature close to the melting point even if the temperature is lower than or equal to the melting point. The temperature gradient of the solution in the container is preferably adjusted to an appropriate temperature gradient as in the case of adding a metal piece. This allows
It is possible to obtain metal particles having a high sphericity in which neither shrinkage cavities nor mirror ball defects are generated.

As the solution 2 to be used, the same solution as in the case where the above-mentioned metal element is added can be used. When adding metal fragments, it was necessary to use a reducing solution to remove the oxide film on the surface of the metal fragments.However, when adding droplets, the solution was not reduced. It does not matter.

[0038]

EXAMPLE A manufacturing method and a manufacturing apparatus according to the present invention were applied to manufacturing of a solder ball. The diameters of the manufactured solder balls are 150 μm, 300 μm, and 760 μm.
A method of adding a solder piece cut out to a constant mass into a container was adopted.

As a container 1 for filling the solution 2, a glass container was used, the cross-sectional dimension was a rectangle of 80 mm × 80 mm, and 15 flat plates were arranged in the container at a pitch of 5 mm.
There were 16 sliding surfaces 3 including the lower wall surface of the container. The material of the flat plate was the same as that of the container. Containers having lengths of 1 m and 0.5 m were prepared. A valve 9 is arranged at the lowermost portion of the container, and by opening the valve 9, the solder balls accumulated at the lower portion of the container can be collected.

Vegetable oil was used as the solution 2 to be filled in the container. A sheet-like electric heater having a predetermined length in the container longitudinal direction was wound as a heating device 7 at a predetermined position above the container 1.
One or more thermocouples were arranged at predetermined positions inside the container 1 to measure the solution temperature, and the solution temperature was fed back to the heating device 7 to control the solution temperature to be constant. Thereby, the solution in the upper part of the container is kept at a high temperature, and the added solder piece can be melted. The lower part of the vessel was provided with a temperature gradient in which the solution temperature became lower as it was closer to the bottom. In this embodiment, natural cooling by air cooling is employed, but a pipe in which cooling water is circulated may be wound around the outer periphery of the container.

As a method of supplying the solder pieces, a method of preparing a solder wire, cutting the solder wire into a fixed length, and adding the cut piece into the container via the parts feeder 10 was adopted. In the manufacture of a solder ball having a diameter of 150 μm, a solder wire having a diameter of 60 μm, a wire diameter of 120 μm for a ball diameter of 300 μm, and a wire diameter of 300 μm for a ball diameter of 760 μm were used. The diameter of the solder wire is preferably about 40% of the diameter of the solder ball. The addition rate of the solder piece is 15 balls.
In the case of 0 μm, the number was 500,000 / min, in the case of the ball diameter of 300 μm, 100,000 / min, and in the case of the ball diameter of 760 μm, 20,000 / min.

For the production of solder balls having a diameter of 300 μm and 760 μm, a container 1 having a length of 1 m was used, and the inclination angle θ of the sliding surface 3 was 60 degrees for a diameter of 300 μm and 30 degrees for a diameter of 760 μm. When manufacturing a solder ball having a diameter of 150 μm, a container having a length of 0.5 m was used, and the inclination angle of the sliding surface was 70 °.

In the method of the present invention, shrinkage cavity defects were generated when the cooling rate of the solder balls in the solution was too high, and mirror ball-like defects were generated when the cooling rate was too low. 2, the longitudinal temperature gradient of the container,
By properly adjusting the cooling rate by finely adjusting the inclination angle of the slide plate 3, shrinkage cavity defects and mirror ball-shaped defects are not observed in any of the embodiments, and the spherical shape of the manufactured solder balls is reduced. A good one could be obtained.

As a comparative example, a method of adding a solder piece while holding a container having a diameter of 100 mm vertically was carried out. In the production of a solder ball having a diameter of 760 μm, the length of the container is 1
m, the cooling rate is too fast, so it was necessary to reduce the temperature gradient of the solution in the container by setting the length of the container to 2 m. The container length was 1 m for a diameter of 300 μm, and 0.5 m for a diameter of 150 μm. Other conditions were the same as those of the above-described present invention.

The temperature gradient of the solution in the container in the longitudinal direction of the container was variously corrected. In each case, a solder ball having a shrinkage defect and a solder ball having a mirror ball-like defect are generated or generated at the same time. Could not be extinguished together. Further, generation of solder balls whose sphericity did not satisfy the requirements was observed.

[0046]

According to the method and the apparatus for producing spherical metal particles, a metal element or a metal droplet is added to a container filled with a solution, and spherical metal particles are obtained in the process of falling into the solution. By sliding the object along the inclined sliding surface of the container, neither shrinkage cavity defects nor mirror ball-like defects occurred, and the shape of the produced metal particles could be stabilized. In addition, by sliding the metal element along the inclined sliding surface of the container, even if the diameter range of the metal particles to be manufactured is wide, only a small number of types of containers need to be prepared. It has become possible to appropriately produce the metal particles of the above.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a spherical metal particle manufacturing apparatus of the present invention for adding a metal piece to a solution.

FIG. 2 is a sectional view showing a spherical metal particle manufacturing apparatus of the present invention for adding metal droplets to a solution.

FIG. 3 is a cross-sectional view showing a spherical metal particle manufacturing apparatus of the present invention having a plurality of sliding surfaces.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 container 2 solution 3 sliding surface 4 metal piece 5 metal droplet 6 metal particle 7 heating device 8 cooling device 9 valve 10 supply device (parts feeder) 11 supply device (cylindrical container) 12 dropping hole 13 molten metal

Claims (10)

[Claims] 1. A metal element is added to a container filled with a heating solution having a reducing action, and the metal element is melted and cooled and solidified in a process of falling in the solution to produce spherical metal particles. A method for producing spherical metal particles, wherein the metal element is slid along an inclined slide surface of the container. 2. A method for producing spherical metal particles by dropping molten metal droplets into a container filled with a solution and cooling and solidifying the metal droplets in the process of falling through the solution. A method for producing spherical metal particles, wherein a droplet is slid down along an inclined sliding surface of the container. 3. The method for producing spherical metal particles according to claim 1, wherein a sliding speed of the metal piece or the metal droplet is adjusted by adjusting an inclination angle of the sliding surface. 4. The inclination angle of the sliding surface is 15 to 75 degrees.
The method for producing spherical metal particles according to claim 3, wherein the degree is set to a degree. 5. The method for producing spherical metal particles according to claim 1, comprising two or more sliding surfaces, wherein the metal element or the metal droplet is slid down along each sliding surface. . 6. A container filled with a solution having a reducing action,
A heating device for heating the solution in the container, and an adding device for adding a metal element in the container, wherein the metal element is added in the container and the metal element is dropped in the solution. An apparatus for producing spherical metal particles by melting and cooling and solidifying pieces, wherein the container has an inclined sliding surface for sliding down metal pieces. 7. A container for filling a solution, and a dropping device for dropping a metal droplet into the container, wherein the metal droplet is added to the container and dropped in the solution. A device for producing spherical metal particles by cooling and solidifying a metal particle, wherein the container has an inclined sliding surface for sliding down metal droplets. 8. The sliding angle of the metal piece or the metal droplet is adjusted by adjusting the inclination angle of the sliding surface, and adjusting the inclination angle of the sliding surface. Or the spherical metal particle manufacturing apparatus according to 7. 9. The inclination angle of the sliding surface is 15 ° to 75 °.
9. The apparatus for producing spherical metal particles according to claim 8, wherein the apparatus can be adjusted within a range of degrees. 10. The apparatus for producing spherical metal particles according to claim 6, wherein two or more sliding surfaces are provided, and a metal piece or a metal droplet slides along each sliding surface. .