JP2001181709A - Method and apparatus for manufacturing fine metal particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently manufacture fine metal particles of a predetermined size with excellent accuracy by cleaning surfaces of the fine metal particles without complicated processes. SOLUTION: The fine metal particle manufacturing apparatus has a measuring unit 100 on an upper portion of a perpendicularly disposed container 9 and forms the fine metal particles by solidifying a molten metal M1 discharged from the measuring unit 100 into a cooling medium 101 contained in the container 9, and the cooling medium 101 is formed of an inert polymer liquid. By discharging the molten metal M1 in the inert polymer liquid, cleaning can be easily achieved after the cooling, and the cleaning process can be simplified.

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 metal spheres which are suitably used for forming ball-shaped bumps on electrodes of a semiconductor device or a printed circuit board.

[0002]

2. Description of the Related Art As a method for producing low-melting minute metal spheres, there are an atomizing method and a method of obtaining metal spheres by dipping a metal piece prepared in a predetermined volume in a heating liquid. Also,
In the method described in JP-A-4-74801, a molten metal is extruded from fine particles in a liquid heated to a temperature equal to or higher than the melting point of the metal.

[0003]

According to the atomizing method, a large amount of metal particles can be obtained in a short time, but it is difficult to make the shape of the particles spherical or uniform, and the yield is extremely high. become worse. According to the method in which the metal piece is dropped on the heating liquid, it is possible to form a substantially perfect spherical shape by the surface tension. However, in order to align the dimensions of the metal pieces to be dropped in advance, it is necessary to perform a press punching process on an ultra-thin plate by rolling or the like, or to perform a process of precisely thinning using a cutter or the like and thinning it with a die or the like. .

[0004] In Japanese Patent Application Laid-Open No. 4-74801, a zone or region having a temperature range equal to or higher than the melting point of metal is provided by filling a vertical pipe with natural oil or the like and using a heater mounted above the vertical pipe. . Then, a low melting point alloy supply pipe having a fine lattice attached in this region is erected so that the fine lattice is located below. The lump of the low melting point alloy is put into the low melting point alloy supply pipe to be melted, and an inert gas is fed from above the low melting point alloy supply pipe. Due to the pressure of this gas, the molten alloy is extruded from the fine lattice and becomes particles, and becomes spherical by passing through the temperature gradient of the vertical tube.

However, in the method described in this publication, the relationship between the grid size and the pressing force is unknown. In any case, the shape of the grains is based on a delicate balance between the surface tension and those factors, and in this method, so-called mixed grains cannot be avoided.

Accordingly, the present applicant has filed Japanese Patent Application No. 10-3104.
According to No. 51 etc., fine metal spheres of predetermined size can be accurately
A method and an apparatus for manufacturing micro metal spheres that can be efficiently manufactured are proposed. In this method or apparatus, a metal to form a metal sphere is heated and melted by a heating means, and the molten metal is injected into a measuring device having a predetermined volume. The measured molten metal is released from the measuring instrument in a molten state, and is cooled to a temperature lower than the melting point by a cooling means, whereby the molten metal is solidified into a spherical shape by surface tension in a cooling process, and thereby a predetermined size is formed at a high temperature. Thus, it is possible to obtain minute metal spheres having different shapes.

Here, when a cooling medium such as oil is used as a cooling means for forming the fine metal spheres, after performing the process of lowering the temperature of the molten metal M1, the surface state of the fine metal spheres is changed. It is necessary to prevent trouble in joining with the member. This is because if the cooling medium such as oil remains attached, the joining property when joining to a semiconductor chip or a substrate by reflow is degraded.

Further, if the size of the minute metal spheres varies, there is a possibility that the bonding property with the substrate may be deteriorated due to factors such as the height from the electrodes when being arranged on the semiconductor chip is not constant. Therefore, it is also indispensable to keep the size of the minute metal sphere with high accuracy.

In view of the above-mentioned circumstances, the present invention provides a method of cleaning a surface of a fine metal sphere without complicated steps, and producing a fine metal sphere of a predetermined size more accurately and efficiently. It is an object to provide a manufacturing method and an apparatus.

[0010]

According to the present invention, there is provided an apparatus for producing fine metal spheres, comprising a measuring unit provided at the top of a vertically arranged container, and cooling the molten metal discharged from the measuring unit into the container. An apparatus for producing fine metal spheres, which is solidified in a medium to form fine metal spheres, wherein the cooling medium is made of an inert polymer liquid.

In one embodiment of the apparatus for producing fine metal spheres according to the present invention, the cooling medium is made of an inert fluoropolymer liquid.

In one embodiment of the apparatus for producing micro metal spheres of the present invention, the specific gravity of the cooling medium is 1.2 or more.

[0013] The apparatus for producing fine metal spheres of the present invention has a measuring unit above a vertically arranged container, and solidifies molten metal discharged from the measuring unit in a cooling medium contained in the container. An apparatus for producing micro-metal spheres for forming micro-metal spheres, wherein the cooling medium comprises oil and an inert polymer liquid placed below the oil.

In one embodiment of the apparatus for producing micro-metal spheres according to the present invention, the inert polymer liquid comprises an inert fluorine-based polymer liquid.

In one embodiment of the apparatus for producing micro metal spheres according to the present invention, the inert polymer liquid has a specific gravity of 1.2 or more.

In one embodiment of the apparatus for producing micro metal spheres of the present invention, the inert polymer liquid contains alcohol.

According to the method for producing fine metal spheres of the present invention, the weighed molten metal is discharged into a vertically arranged container containing a cooling medium, and the molten metal is solidified in the cooling medium to form the fine metal spheres. A method for producing a minute metal sphere to be formed,
An inert polymer liquid is used as the cooling medium, and the molten metal is cooled and solidified by the cooling medium.

In one embodiment of the method of the present invention for producing fine metal spheres, an inert fluoropolymer liquid is used as the inert polymer liquid.

In one embodiment of the method for producing fine metal spheres of the present invention, a liquid comprising the inert polymer liquid and oil is used as the cooling medium, and after cooling with the oil, the inert liquid is cooled. Cooling by molecular liquid,
The molten metal is solidified.

The apparatus for manufacturing micro-metal spheres of the present invention has a measuring unit above a vertically arranged container, and solidifies molten metal discharged from the measuring unit in a cooling medium contained in the container. An apparatus for manufacturing micro metal spheres for forming micro metal spheres, wherein at a temperature of 200 ° C. at which the molten metal melts, the viscosity of the cooling medium is 2 cSt or more and 20 c or more.
St is kept within the range of not more than St, and the viscosity of the cooling medium reduces the falling speed of the molten metal in the cooling medium.

In one embodiment of the apparatus for producing micro-metal spheres according to the present invention, the cooling medium is made of oil, a mixed liquid obtained by adding a thickener to oil, or a mixed liquid obtained by mixing oil with a highly viscous liquid.

According to the method for producing fine metal spheres of the present invention, the weighed molten metal is discharged into a vertically arranged container containing a cooling medium, and the molten metal is solidified in the cooling medium to form the fine metal spheres. A method for producing a minute metal sphere to be formed,
At a temperature of 200 ° C. at which the molten metal melts, the viscosity of the cooling medium is kept in a range of 2 cSt to 20 cSt, and the viscosity of the cooling medium reduces the falling speed of the molten metal in the cooling medium.

In one embodiment of the method for producing micro metal spheres of the present invention, as the cooling medium, oil, a mixed liquid obtained by adding a thickener to oil, or a mixed liquid obtained by mixing a high-viscosity liquid with oil is used. .

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A preferred embodiment of a method and an apparatus for manufacturing a fine metal sphere according to a first embodiment of the present invention will be described below with reference to the drawings.

First, the minute metal spheres in the present embodiment are, for example, formed by soldering, for example. In a manufacturing process of a semiconductor device, in order to connect an electrode portion of a semiconductor element to an external circuit or the like, the two are joined via bumps formed of minute metal spheres. A small metal sphere suitable for this bump is targeted. In particular, a diameter of several hundred μm or less is obtained.

FIG. 1 shows an example of a schematic configuration of an apparatus for producing fine metal spheres used in the method of the present invention. First, with reference to FIG. 1, the configuration of the measuring unit 100 in the apparatus for manufacturing micro metal spheres will be mainly described. In the drawing, 1 and 2 are an upper block and a lower block for supplying and discharging molten metal M, 3 is a metal charging section, 4 is an injection passage formed in the upper block 1, and 5 is a molten metal formed in the lower block 2. It is an outlet for metal M.

In this example, the upper block 1 and the lower block 2 are, for example, circular (see FIG. 2) and fixed at predetermined positions of the apparatus. Upper block 1 and lower block 2
It is preferably formed of a material such as metal, resin or ceramics which does not get wet with solder. Alternatively, a coating made of these materials may be coated with Teflon or the like on the surface, and a material having heat resistance and not being thermally deformed is preferable.

As the simplest configuration example, the injection path 4 and the discharge port 5 may be diametrically opposed to each other as shown in FIG.

Reference numeral 6 denotes a weighing device rotatably mounted between the upper block 1 and the lower block 2, and 7 denotes a weighing unit provided on the weighing device 6. As a simplest configuration example, as shown in FIG. It may have measuring parts 7a and 7b which are diametrically opposed. The measuring units 7a and 7b are precisely formed to have a predetermined volume. Reference numeral 8 denotes a support shaft that rotationally drives the measuring device 6.

In this example, the measuring instrument 6 is preferably formed in a thin disk shape from a material such as metal, resin or ceramics which does not wet with solder. The weighing device 6 may be made of these materials, and may be coated with Teflon or the like on the surface thereof. Further, the weighing device 6 has heat resistance and does not deform thermally. The material for forming the measuring device 6 and the like may be the same as those of the upper block 1 and the lower block 2, but are not necessarily formed of the same material. When the weighing device 6 is mounted between the upper block 1 and the lower block 2, the weighing device 6 is mounted exactly up and down without a gap and is rotatable. Measuring unit 7
a and 7b are formed through the disc of the meter 6 at positions that can be aligned with the injection path 4 and the discharge port 5, respectively.

Here, in addition to the case where the pair of measuring portions 7a and 7b are provided so as to face each other as shown in FIG. 3, the measuring device 6 may be arranged in the circumferential direction (in the illustrated example, divided into four circumferential portions) and / or A plurality of rows or a plurality of pairs may be provided in the radial direction (three rows in the illustrated example). Thus, the plurality of measuring units 7
Is provided, a plurality of injection paths 4 and discharge ports 5 are provided in a manner corresponding to the arrangement of the measuring section 7.

The upper block 1, the lower block 2 and the parts associated therewith are housed in a container (made of glass or the like) 9 in a unitized form as shown in FIG. Around the container 9, a heating coil 10 as heating means for heating and melting the metal to form the metal sphere is arranged. The inside of the container 9 is configured as a fluid tank. In this example, a liquid cooling medium 11 as cooling means for cooling the molten metal M discharged from the measuring device 6 to a temperature equal to or lower than the melting point is stored.

The heating coil 10 may be, for example, a heating wire coil or a high-frequency coil. The heating coil 10 heats the metal charged from the metal charging section 3 to maintain the molten metal M. Thus, the corresponding portion of the heating coil 10 in the container 9 is set to a heating zone or area. In addition, a portion that is separated downward from the heating coil 10 in the container 9 is:
Set in a cooling zone or area. By providing the heating zone and the cooling zone above and below, a temperature gradient is generated in the container 9.

In the above configuration, the metal charged from the metal charging unit 3 is in a molten metal M state in the injection path 4 by the heating coil 10. As shown in FIG. 1, the molten metal M is injected into the measuring section 7a located immediately below the injection path 4. When the molten metal M is filled in the measuring unit 7a, the measuring device 6 is driven to rotate by the support shaft 8 next. At this time, the upper and lower surfaces of the measuring device 6 are in sliding contact with the surfaces of the upper block 1 and the lower block 2, that is, the molten metal M can be accurately measured by being completely rubbed with the predetermined volume of the measuring portion 7a.

The measuring section 7a filled with the measured molten metal M moves right above the discharge port 5 located on the opposite side. Then, the molten metal M in the measuring section 7 a
From the molten state (M1). The released molten metal M1 descends from the heating zone to the cooling zone in the oil 11 of the fluid tank. During this descent, the molten metal M1
Is cooled by the oil 11 to a temperature lower than the melting point, and in this cooling process, is solidified into a spherical shape by surface tension, whereby a fine metal sphere B of a predetermined size and shape is formed with high precision.

By repeating the above operation, the measuring section 7
a, 7b alternately weighs the molten metal M to continuously obtain the fine metal spheres B. Therefore, the minute metal spheres B can be manufactured with extremely high precision and efficiency.

Here, after performing a process of lowering the temperature of the molten metal M1 using oil or the like as a cooling medium to form the fine metal spheres B, the cooling medium is removed from the surface of the fine metal spheres B. There is a need. This is because if the cooling medium such as oil remains attached, the joining property when joining to a semiconductor chip or a substrate by reflow is degraded.

The first embodiment makes it possible to easily remove the cooling medium 11 from the surface of the fine metal sphere B after its formation.

FIG. 4 is a schematic view showing an apparatus for manufacturing a fine metal sphere B according to the first embodiment. In FIG. 4, a container 9 contains a liquid cooling medium (fluorine-based polymer liquid 101). The measuring unit 100 described with reference to FIG. From the measuring unit 100, the molten metal M1 is discharged one after another.
The released molten metal M1 is spheroidized by surface tension in a cooling medium.

A heating coil 10 such as the high-frequency coil described with reference to FIG. Below the heating coil 10, the fluoropolymer liquid 101 is directed downward from the position where the measuring unit 100 is disposed.
A predetermined water cooling pipe (not shown) is arranged such that a predetermined temperature gradient is formed in the water cooling pipe.

The cooling medium in this embodiment is made of a fluorine-based polymer liquid (fluorinated inert liquid) 101, and is contained from the bottom of the container 9 to the top of the measuring unit 100. The fluorine-based polymer liquid 101 is a liquid having a chemical formula of, for example, (C ₅ F ₁₁ ) _3n and a specific gravity of about 1.2 or more. Conventional cooling medium, oil of specific gravity of about 0.8 has been mainly used, but when the molten metal M1 falls in the cooling medium, if the specific gravity is 1.2 or more in the cooling medium,
Buoyancy is generated by dropping in oil having a specific gravity of about 0.8, and the drop can be performed slowly, so that the sphericity of the fine metal sphere B can be improved. The fluorine-based polymer liquid 101
In, the specific gravity increases as the number of fluorine substitutions increases. An example of such a fluorine-based polymer liquid 101 is Fluorinert (trade name, manufactured by Sumitomo 3M).

The molten metal M1 measured by the measuring unit 100 is discharged into the fluoropolymer liquid 101 in the container 9 in a molten state. Molten metal M1 released
Falls downward in the fluoropolymer liquid 101 while spheroidizing. The boiling point of the fluoropolymer liquid 101 is stable at about 150 ° C. to 215 ° C.
1 does not react with the solder or the like constituting the molten metal M1.
Is cooled according to the temperature gradient of the fluoropolymer liquid 101 as it falls downward in the container 9. When the released molten metal M1 reaches the bottom of the container 9,
The molten metal M1 solidifies to form the fine metal sphere B.

The solid fine metal spheres B are taken out of the fluoropolymer liquid 101 and washed. Since the fluorine-based polymer liquid 101 is excellent in cleaning properties, the fluorine-based polymer liquid 101 attached to the surface of the fine metal sphere B is
It can be easily removed by using alcohol such as ethanol or acetone.

The polymer liquid is not limited to a fluorine-based liquid, and various inert polymer liquids can be used. Further, a mixture of several kinds of inert polymer liquids may be used. Further, for example, a mixture of several kinds of fluorine-based polymer liquids having different fluorine substitution numbers may be used.

In this embodiment, the measuring unit 10
Although the aspect in which the molten metal M1 released from 0 is cooled by the liquid fluoropolymer liquid 101 has been described,
The molten metal M released from the fluorine-based polymer liquid 101 into a gas (steam) into the container 9 and discharged into the gas atmosphere
It is also possible to cool 1. In this case, it is desirable to further add a liquid cooling medium below the gas to perform further cooling.

As described above, according to the first embodiment of the present invention, the molten metal M1 is discharged into the fluorinated polymer liquid 101 as a cooling medium, so that cleaning after solidification is facilitated. The cleaning process can be simplified.

(Second Embodiment) Next, a preferred embodiment of a method and an apparatus for manufacturing a fine metal sphere B according to a second embodiment of the present invention will be described with reference to the drawings. In the second embodiment, the cooling medium can be easily removed after the minute metal spheres B are formed in the same manner as in the first embodiment.

FIG. 5 is a schematic view showing an apparatus for manufacturing minute metal spheres B according to the second embodiment. In FIG. 5, a container 9 contains a cooling medium composed of two kinds of liquids. That is, the container 9 contains the fluoropolymer liquid 101 and the oil 102 as described in the first embodiment.
And is put. The fluoropolymer liquid 101 has a specific gravity of 1.2 or more as described above,
02 has a specific gravity of about 0.8,
And the oil 102 is separated from the fluoropolymer liquid 1
Located at the top of 01.

The molten metal M 1 discharged from the measuring unit 100 is first discharged into the oil 102. Oil 1
Numeral 02 is maintained at a predetermined temperature by the heating coil 10 arranged outside the container 9, where the molten metal M <b> 1 is spheroidized in the oil 102 by surface tension.

Thereafter, the molten metal M1 drops downward in the oil 102, and eventually, the fluoropolymer liquid 1
Fluorinated polymer liquid 10 beyond boundary 103
Fall into one. In the fluoropolymer liquid 101, a predetermined temperature gradient is set downward by the heating coil 10 or the cooling pipe, and the molten metal M1 solidifies as it falls downward. At the same time, the oil 102 adhering to the surface of the molten metal M1 is separated in the fluoropolymer liquid 101, and the surface of the molten metal M1 is covered by the fluoropolymer liquid 101.

That is, by transferring the molten metal M1 from the oil 102 to the fluoropolymer liquid 101, the oil 102 attached to the surface of the molten metal M1 can be completely removed. Small metal sphere B solidified to solid
Is taken out of the fluoropolymer liquid 101 and washed. Since the fluorine-based polymer liquid 101 is excellent in cleaning properties, the fluorine-based polymer liquid 101 attached to the surface of the fine metal sphere B can be easily removed by using alcohol such as ethanol or acetone. Therefore, unlike the case where cooling is performed only with the oil 102, it is possible to easily perform cleaning after the molten metal M1 is solidified and the minute metal spheres B are formed.

As shown in FIG. 5, the oil 102 and the fluoropolymer liquid 101 are completely separated at the boundary 103 due to the difference in specific gravity. Also, if alcohol such as methanol or ethanol is contained in the fluorine-based polymer liquid 101, dirt such as oil adhering to the surface of the molten metal M1 can be removed by the alcohol. Since the molecular liquid 101 is separated, components such as dirt and the like are mixed with the alcohol and the fluoropolymer liquid 101.
From the fluoropolymer liquid 101
Can be reproduced.

As described above, according to the second embodiment, the molten metal M1 is supplied from the measuring unit 100 to the oil 1
02, and then transferred into the fluoropolymer liquid 101 to remove the oil 1 adhering to the surface of the molten metal M1.
02 can be removed, and washing after coagulation can be easily performed.

(Third Embodiment) Hereinafter, a preferred embodiment of a method and an apparatus for manufacturing micro metal spheres according to a third embodiment of the present invention will be described with reference to the drawings. As described in each of the above-described embodiments, for example, the first embodiment, the molten metal M1 discharged from the measuring unit 100 falls downward in a cooling medium such as oil and the like.
0, it is cooled as it falls due to the temperature gradient of the cooling medium set by the cooling pipe or the like, and becomes a minute metal sphere B.

Here, the falling speed of the molten metal M1 in the cooling medium has a large effect on the sphericity when the molten metal M1 solidifies to form the fine metal spheres B. The sphericity is degraded by the resistance of the medium. Therefore, appropriately controlling the falling speed in the cooling medium is extremely important for producing high quality fine metal spheres B. In the third embodiment, the falling speed in the cooling medium is controlled to improve the sphericity of the minute metal sphere B.

The manufactured minute metal sphere B is used as a bump for connecting an electrode portion of a semiconductor element to an external circuit or the like in a semiconductor device manufacturing process. The size of the fine metal sphere is determined by the size of the electrode in each of the semiconductor element and the external circuit, and the fine metal sphere of various sizes is used according to the application and purpose.

Here, since the falling speed in the cooling medium is proportional to the square of the radius of the fine metal sphere B, when manufacturing the fine metal sphere B having a diameter of about 100 μm, the falling speed is very small. It hardly affects the size of the metal sphere B.

However, depending on the type of the semiconductor device, 4
A small metal sphere B having a diameter of about 00 μm to 800 μm is used. When such a relatively large small metal sphere B is formed, it is particularly necessary to control the falling speed in the cooling medium.

In this embodiment, 400 μm to 800 μm
When manufacturing the fine metal spheres B having a diameter of the order of magnitude, oil whose viscosity increases near the melting point of the fine metal spheres B is used.

FIG. 6 is a schematic diagram showing a configuration of a manufacturing apparatus for a fine metal sphere B according to the third embodiment. As shown in FIG. 6, also in the manufacturing apparatus of the fine metal sphere B according to the third embodiment, the container 9, the weighing unit 100 arranged in the container 9, and the weighing unit 100 And an oil 104 filled up to the top. A heating coil 10 is arranged on the outer periphery of the container 9.

As shown in FIG. 6, the oil 4 put in the container 9 is heated to a predetermined temperature by the heating coil 10 in the heating zone, and is lowered downward by a member such as a cooling pipe (not shown) in the cooling zone. A temperature gradient is formed toward it. Here, the problem of drop speed is
Mainly in the upper part of the cooling zone.

In general, since the viscosity of oil decreases as the temperature increases, the drop speed decreases due to the decrease in viscosity, particularly in the vicinity of a cooling zone set at a temperature near the melting point of the molten metal M1. Become noticeable.

FIG. 7 shows an oil 1 according to the third embodiment.
It is a schematic diagram which shows the characteristic of No. 04. FIG. 8 shows the characteristics of a normal oil for comparison. here,
7 and 8 show the viscosities at respective temperatures of 40 ° C., 100 ° C., and 200 ° C.

As shown in FIG. 7, the oil 104 used in this embodiment is, for example, of the following three types, and has a viscosity of 5.8 cSt to 7.6 c at 200 ° C.
It is set in the range of St. On the other hand, in a normal oil as shown in FIG.
It is about St. With a viscosity of 1.0 cSt, a diameter of 400μ
The minute metal sphere B of m to 800 μm falls at a very fast falling speed, and the resistance at that time causes a large change in sphericity. However, as in the present embodiment, the viscosity at 200 ° C. is 6 cSt to 7 cSt. Degree or more, more preferably 2c
By using the oil in the range of St to 20 cSt, it is possible to reduce the falling speed of the molten metal M1 discharged from the measuring unit 100. As the oil 104, the above-mentioned viscosity may be ensured by mixing several kinds of oils having different viscosities, or the above-described viscosity may be ensured by mixing a thickener. Is also good.

FIG. 9A shows the oil 10 shown in FIG.
4 shows the sphericity when 4 is used. FIG.
(B) shows the sphericity when the oil shown in FIG. 8 is used. Thus, by increasing the viscosity at 200 ° C., the sphericity of the completed fine metal sphere B can be improved.

On the other hand, the lower part of the cooling zone,
Since it is necessary to take out the solidified minute metal spheres B at the lower part of the, high viscosity oil cannot be used. In the present embodiment, as shown in FIG. 7, oil having a viscosity at 40 ° C. of about 100 cSt to about 400 cSt is used, so that the solidified fine metal spheres B can be taken out. Generally, when the viscosity at high temperature is increased, the viscosity at low temperature is also increased. For example, when the viscosity becomes about 1000 cSt, the oil becomes syrup-like, and it is difficult to take out the minute metal spheres B from this. In the oil 4 used in the present embodiment, although the viscosity at 200 ° C. was increased to reduce the falling speed, the viscosity at 40 ° C. was 4
It is suppressed to about 00 cSt or less. Therefore, at the upper part of the cooling zone, a predetermined viscosity capable of suppressing the falling speed can be secured, and at the lower part of the cooling zone, the viscosity required for taking out can be made low.

As described above, according to the third embodiment of the present invention, it is possible to reduce the falling speed of the molten metal M1 discharged from the measuring unit 100. Therefore, it is possible to manufacture the fine metal sphere B with improved sphericity.

Further, even if the viscosity at a high temperature is increased,
Since the viscosity of the oil 104 is set so that the viscosity at a low temperature does not become larger than a predetermined value, the solidified fine metal spheres B can be easily taken out of the oil 104.

[0069]

According to the present invention, cleaning after solidification can be easily performed by discharging molten metal into an inert polymer liquid as a cooling medium, and the cleaning process can be simplified. Becomes possible.

Further, according to the present invention, it is possible to reduce the falling speed of the released molten metal. Therefore, it is possible to manufacture a fine metal sphere with improved sphericity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a measuring unit of an apparatus for manufacturing micro metal spheres according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a measuring unit of the apparatus for manufacturing fine metal spheres according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a configuration of a weighing unit of the apparatus for manufacturing micro metal spheres according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a schematic configuration of a manufacturing apparatus for a micro metal sphere according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a schematic configuration of a manufacturing apparatus of a minute metal sphere according to a second embodiment of the present invention.

FIG. 6 is a schematic diagram showing a schematic configuration of a manufacturing apparatus of a micro metal sphere according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating characteristics of oil according to a third embodiment of the present invention.

FIG. 8 is a schematic diagram showing characteristics of a normal oil as a comparative example in the third embodiment of the present invention.

FIG. 9 is a schematic diagram showing the sphericity of a small metal sphere according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper block 2 Lower block 3 Metal input part 4 Injection path 5 Discharge port 6 Meter 7, 7a, 7b Metering part 8 Support shaft 9 Container 10 Heating coil 11 Cooling medium 100 Metering unit 101 Fluoropolymer liquid 102, 104 Oil 103 Boundary

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kohei Tatsumi 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technology Development Division F-term (reference) 3L044 AA03 BA05 CA04 DB02 KA01 KA04 4K017 AA04 BA01 BB01 CA01 DA01 EC01 EK02 FA25 FA26

Claims (14)

[Claims] 1. A fine metal sphere having a measuring unit at the top of a vertically arranged container, and solidifying molten metal discharged from the measuring unit in a cooling medium contained in the container to form a fine metal sphere. The manufacturing apparatus for fine metal spheres, wherein the cooling medium is made of an inert polymer liquid. 2. The apparatus according to claim 1, wherein the cooling medium is made of an inert fluoropolymer liquid. 3. The apparatus according to claim 1, wherein the specific gravity of the cooling medium is 1.2 or more. 4. A fine metal sphere having a measuring unit on an upper part of a vertically arranged container, and solidifying a molten metal discharged from the measuring unit in a cooling medium contained in the container to form a fine metal sphere. The manufacturing apparatus for micro metal spheres, wherein the cooling medium is composed of an oil and an inert polymer liquid placed under the oil. 5. The apparatus according to claim 4, wherein the inert polymer liquid is made of an inert fluorine-based polymer liquid. 6. The apparatus according to claim 4, wherein the specific gravity of the inert polymer liquid is 1.2 or more. 7. The liquid according to claim 4, wherein the inert polymer liquid contains an alcohol.
Item 3. The apparatus for producing a minute metal sphere according to the above item. 8. A method for producing fine metal spheres, comprising releasing a weighed amount of molten metal into a vertically arranged container containing a cooling medium, and solidifying the molten metal in the cooling medium to form fine metal spheres. A method for producing fine metal spheres, wherein an inert polymer liquid is used as the cooling medium, and the molten metal is cooled and solidified by the cooling medium. 9. The method according to claim 8, wherein an inert fluoropolymer liquid is used as the inert polymer liquid. 10. A liquid comprising the inert polymer liquid and oil as the cooling medium. After cooling with the oil, cooling with the inert polymer liquid is performed to solidify the molten metal. The method for producing a fine metal sphere according to claim 8, wherein: 11. A fine metal sphere having a measuring unit at the top of a vertically arranged container, and solidifying a molten metal discharged from the measuring unit in a cooling medium contained in the container to form a fine metal sphere. Wherein the viscosity of the cooling medium is kept within the range of 2 cSt to 20 cSt at a temperature of 200 ° C. at which the molten metal melts, and the viscosity of the cooling medium causes the molten metal to fall into the cooling medium. An apparatus for producing micro metal spheres, wherein the speed is reduced. 12. The fine metal spheres according to claim 11, wherein the cooling medium is made of oil, a mixed liquid obtained by adding a thickener to oil, or a mixed liquid obtained by mixing a highly viscous liquid with oil. manufacturing device. 13. A method for producing fine metal spheres, comprising discharging a measured amount of molten metal into a vertically arranged container containing a cooling medium, and solidifying the molten metal in the cooling medium to form fine metal spheres. At a temperature of 200 ° C. at which the molten metal melts, the viscosity of the cooling medium is maintained in the range of 2 cSt to 20 cSt, and the viscosity of the cooling medium reduces the falling speed of the molten metal in the cooling medium. A method for producing a metal microsphere, comprising: 14. The cooling medium according to claim 1, wherein oil, a mixed liquid obtained by adding a thickener to oil, or a mixed liquid obtained by mixing a high-viscosity liquid with oil is used.
3. The method for producing a metal microsphere according to item 3.