JPH10211469A - Manufacturing device for spherical grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the mass production of spherical grains of superior shape accuracy in a cell chamber constituting a part of a manufacturing device for spherical grains manufactured by vibrating a liquefied stock solution, cutting the stock solution into uniform droplets and dropping them. SOLUTION: Nozzles 12 are bored on positions including on a face projecting a 90% contracted face of an end face of a horn 6, and preferably formed into one line disposition forming a circle. The shape of the nozzles 12 is of funnel shape, and the angle of apex α of conical sections is in the range of 60 deg.-150 deg., and the length (h) of straight sections is 0.5-3 times the opening diameter (d) and the thickness H of a nozzle plate 13 is formed in the range of 0.3mm-5mm so that the flow of the stock solution is smoothened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing apparatus for mass-producing uniform spherical particles made of metal, various resins, cemented carbide, ceramics, etc. The present invention relates to a configuration of a cell chamber incorporated in an apparatus manufactured by manufacturing.

[0002]

2. Description of the Related Art There are several methods for producing spherical particles made of metal, various resins, and the like. For example, in the prior art for mass-producing solder balls, there are a method of casting in a mold and a method of forming a solder wire. There is a method in which a high-temperature heat transfer medium oil with a thermal gradient is melted in the upper high-temperature part and hardened in the lower low-temperature part after mechanical cutting, and furthermore, spray dryer method, tumbling granulation method, atomizing method, etc. Seems to have been adopted. Since these manufacturing methods are widely known technologies, details in actual manufacturing are accumulated as know-how of the manufacturing company and many parts are not made public. Under such circumstances, the present inventors have created a method for mass-producing spherical particles with uniformity and high precision based on a completely different idea from the above-mentioned conventional technology, and have already understood the basic concept thereof. Published in some magazines (Boundary, April 1994).

An outline of the contents described in this magazine is introduced below. First, a solution is pumped up from a tank containing a raw material solution and injected into a cell chamber. The cell chamber has a cylindrical shape, and the bottom surface is closed by a disk. A through-hole is formed in the disk to form a nozzle, and the solution sent to the cell chamber is extruded from the nozzle. that time,
The shape of the solution flowing out from under the nozzle is one of the following three. One is a drop that drips when the flow velocity is low, and the other is a droplet that scatters around the outlet when the flow velocity is high. The other case is in the middle, where the solution is in a laminar flow region and has a stable columnar flow immediately after flowing out of the nozzle. This is called a liquid column. It has been found that the flow rate that creates this condition is a function of the surface tension of the solution, the diameter of the nozzle, and the density of the solution, and selecting conditions for laminar flow is not very difficult. The solution that has become a liquid column is also spontaneously cut off at that point, and falls as droplets.

[0004] If the cutting that occurs at the tip of the liquid column occurs at the same timing, a uniform droplet can be formed, but when left naturally, it is usually irregular. In order to cut the liquid uniformly, a vibration oscillator is incorporated in the cell so as to forcibly shake the liquid. Since the surface of the vibration transmitter in the cell trembles and shakes, the solution itself also trembles at a certain period, and the solution is uniformly cut at the same timing. Dabora has been working with Rayleigh
By vibrating at a frequency called the maximum instability frequency in a non-viscous fluid, which is to be studied in ileigh), a uniform droplet has been successfully created.

The present inventors have succeeded in calculating the frequency at which the effluent is cut uniformly. Although the details of the calculation formula are omitted here, it is expressed as a function of the velocity of the liquid column and the diameter of the nozzle. According to the calculation, if the diameter of the particle is as small as 1 mm to 30 μm, the vibration The number is about 10 Hz to 100 kHz. The region of low frequency is the region of normal sound waves, and the frequency for producing small particles is the region of ultrasonic waves.

[0006] Since a solution such as a molten metal can be dropped as uniform droplets by the above-described method, the droplets should be naturally cooled and formed as uniform spherical particles. . However, in practice, it was confirmed that the droplets ejected from the nozzle were droplets with uniform grains, but the particles obtained on the floor were irregular.
This is because the drop velocity of the granules changes due to the air resistance during the fall, and coalescence of the granules approaching each other occurs. In order to prevent this, a method was adopted in which an electrode was placed at the tip of the nozzle and applied to the liquid column. It is charged by electrostatic induction, and the charged liquid column is cut into uniform droplets by the applied vibration. When the distance between the droplets is short, the droplets are repelled by electrostatic repulsion, so that the droplets fall without coalescence and are cooled by air to form uniform spherical particles.

[0007]

SUMMARY OF THE INVENTION The inventors of the present invention have intensively studied and, in addition to the contents of the above-mentioned journal publications, have found various technical problems for stably producing spherical granules. Faced and resolved them. The present invention relates to the configuration of a cell chamber, which is one of the technical problems to be solved. Specifically, the present invention relates to the arrangement, shape, material, conduit material, horn material, etc. of nozzles and nozzle plates. By studying, it is possible to stably generate droplets having a uniform size.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the invention according to claims 1 to 4 is a method in which the material of the spherical particles to be produced is first liquefied. Is done. Liquefaction is performed by melting or slurrying. This manufacturing apparatus basically includes a cell chamber, a vibration transmitter, and a nozzle plate serving as a bottom surface of the cell chamber. The vibration transmitted from the vibration transmitter is transmitted to the cell chamber via a horn extending into the cell chamber. Shake the injected stock solution. A nozzle is drilled in the nozzle plate. At this time, the nozzle is positioned at the tip of the horn around the axis of the horn.
The% reduction plane is arranged in the plane of projection onto the nozzle plate.

[0009] In addition, the shape of the nozzle is a funnel comprising a combination of a conical hole opening upward and a straight hole connected to the lower end thereof, and the conical hole has a cone opening angle of 60 ° to 150 °. The straight hole has a length of 0.5 to 3 times the diameter of the straight hole, and the thickness of the nozzle plate is 0.3 mm to 5 mm.
mm. The nozzles are arranged on the nozzle plate so as to form a circle orbiting in a line.

Further, the nozzle plate is made of any one of stainless steel, cemented carbide and ceramics, or made of a general steel material, stainless steel, cemented carbide and ceramics as a base material, and further coated with an inorganic substance. Alternatively, it is formed by coating in multiple layers.

The invention according to claim 5 is characterized in that a conduit for guiding the undiluted solution from the raw material tank to the cell chamber is formed by a flexible heat-resistant pipe.

According to a sixth aspect of the present invention, the horn is formed of ceramics.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the arrangement of the nozzles on the projection surface of the horn tip surface on the nozzle plate with a 90% reduction surface is specifically described in a solder ball manufacturing experiment. Although the details will be described later, the comparison between the case where the nozzles are arranged within the 90% plane as described above and the case where the nozzles are arranged beyond the 90% plane as described above shows This is because there was a difference in quality uniformity between good and bad. The reason for this is that if the nozzle is located near the outer edge of the horn tip or the nozzle is located off the tip of the horn, the propagation force of the vibration due to the distance from the horn tip decreases, Vibration due to the diagonal direction weakens,
It is thought that the reason for this is that the uniformity of the droplets is not ensured by lowering the liquid drainage force.

The reason why the shape of the nozzle is funnel-shaped is to allow the stock solution to flow smoothly through the nozzle. For example, when the stock solution is obtained by slurrying,
If the nozzle shape is inappropriate, the slurry gels and gradually accumulates near the inlet of the nozzle, and narrows or eventually blocks the inlet of the nozzle. The funnel shape smoothes the flow of droplets and prevents deposition, and the numerical value of the angle range recommended for the same purpose is also limited for the cone opening angle of the conical hole of the nozzle. It was done. Further, the upper limit of the length of the nozzle-shaped straight hole portion is set to be three times the diameter of the straight hole, which is a length range in which the undiluted solution does not clog. On the other hand, the lower limit of the length of the straight hole is set to 0.5 times the diameter of the straight hole as a minimum length range in which uniform droplets can be generated.

Regarding the lower limit of the thickness of the nozzle plate,
This is evident from the fact that when the thickness is too thin, the nozzle plate itself vibrates due to the vibration from the vibration transmitter. The minimum thickness of the nozzle plate that is not self-excited is 0. 3 mm was obtained. On the other hand, the upper limit of the thickness of the nozzle plate is limited by the nozzle shape, and the relationship between the diameter of the straight hole (specifically, about 1 mm or less) and its length, the shape of the conical hole, and the like, The maximum thickness at which good droplets can be stably obtained is 5 mm.

The cell chamber and the horn are usually designed on the basis of a cylinder which is easy to manufacture. However, such a configuration is, as described above, uniform in strength and direction of vibration propagation. In view of the performance, it is more preferable that the tip of the horn is formed in a circular shape and the nozzles on the nozzle plate facing the horn are arranged in a circular shape. Of course, the array circle drawn by the nozzle is included in the projected circle of the 90% reduced circle at the tip of the horn so that the liquid running force does not decrease. At this time, the nozzles are arranged in a line. That is, when arranged in a circle, for example, a double circle is prevented. This is because in the case of a double circle arrangement, when the undiluted solution flows out of the nozzle, the underwater cutting causes interference between the inner circle side and the outer circle side, causing a phenomenon that uniform cutting is not performed.

The material of the nozzle plate is stainless steel for the purpose of preventing rust that occurs in the case of a water-soluble slurry or the like. Cemented carbides and ceramics are used for suppressing abrasion due to a stock solution and extending the life of the nozzle. used. The coated nozzle plate not only improves the abrasion resistance, but also ensures a smooth and stable flow of the stock solution by forming a coating that improves the wettability with the stock solution. Since the coating has a rust-preventing action, a general steel material can be used as the base material. Such coatings include, for example, diamond, diamond-like carbon (DLC), CrN,
SiO ₂ , Al ₂ O ₃ , Cr ₂ N, TiC, TiN, AlN
And the like, and these are coated on the base material in one or more layers by a chemical vapor deposition method, a physical vapor deposition method, or the like.

The conduit for guiding the undiluted solution from the raw material tank to the cell chamber is formed by a flexible heat-resistant pipe. This is because, when a rigid conduit such as a stainless steel tube is used, the vibration transmitted from the vibration transmitter is
This is because it is attenuated under the influence of the rigid steel pipe, and the intended purpose of generating uniform droplets cannot be achieved. Therefore, a damping of vibration is prevented by using a heat-resistant and flexible piping material such as a Teflon tube.

To prevent heat from escaping through the horn, and to prevent heat from being transmitted to the body of the vibration transmitter,
Ceramics are used as the horn material.

[0020]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present spherical particle producing apparatus. FIG. 1 schematically shows the basic structure of the apparatus. In this figure, the raw material tank 1 includes:
A stock solution liquefied by melting or slurrying the material of the spherical particles to be produced is stored. This stock solution is injected into the cell chamber 3 through the conduit 2. There are several methods for injecting the undiluted solution, such as extrusion using gas pressure. Here, a high-temperature high-precision pump 4 is used as a driving source.

On the other hand, in the cell chamber 3, a horn 6 extends from a vibration transmitter 5 which is an ultrasonic transmitter, and has a built-in tip. Since the configuration below the cell chamber 3 is not the subject of the present invention, it is assumed to be as described in the above-mentioned magazine. That is, below the cell chamber 3, an electrode 8 for applying a charge to the undiluted solution that falls as a droplet 7 from the cell chamber 3 is provided.
Even if the droplets approach each other, the droplets 7 charged by the electrostatic induction do not repel each other and do not unite. The droplets 7 are air-cooled and / or air-dried during the fall, and solidified as spherical particles and collected. Stored in container 9. Such a method of dropping in the air is particularly suitable for a stock solution that has been made into a slurry, and another method such as oil cooling may be used for a stock solution obtained by melting, but a detailed description is not given. Omitted.

FIG. 2 is an enlarged sectional view of the cell chamber 3. The cell chamber 3 is formed by combining a disk or a flanged cylinder as a part to form a main body 10, and the parts are integrally fastened by bolts 11. A nozzle plate 1 having a nozzle 12 is provided on the bottom of the cell chamber 3.
3 which are sandwiched via a packing 14 for preventing liquid leakage.

In the case of a material whose undiluted solution is obtained at a high temperature, such as a molten metal, a temperature drop occurs during the flow from the raw material tank 1 to the cell chamber 3 or in the cell chamber 3. If it becomes necessary to reheat the stock solution, which has deteriorated due to the temperature drop, to recover the fluidity of the stock solution, a heater is arranged around the outer periphery of the cell chamber 3 for heating. Therefore, a material excellent in heat conduction, such as an aluminum alloy, is suitable for the cell chamber 3. At the same time, a hard alumite treatment is preferably applied to the inner wall surface of the cell chamber 3 in order to prevent a reaction between the stock solution, which is a molten metal, and the aluminum alloy.

The tip of a horn 6 extending from the vibration transmitter 5 is built in the center of the cell chamber 3. Although the inside of the cell chamber 3 is a simple columnar space, the upper portion thereof is formed with irregularities between the horn 6 and the flange.
By incorporating an O-ring 15 into the uneven portion, leakage of the stock solution is prevented. In addition to the above, it is necessary to seal a portion where the seam is formed unavoidably due to the configuration.
An O-ring 16 is incorporated in the lower part of the. Horn 6
The horn 6 is formed of ceramic so that when the undiluted solution has a high temperature, heat does not escape through the horn 6 and does not reach the main body of the vibration transmitter 5.

One end of the conduit 2 is screwed into the side surface of the main body 10, and the undiluted solution pumped up from the raw material tank 1 is injected into the cell chamber 3 from the conduit 2 through the through hole 17. A flexible heat-resistant pipe is used for the conduit 2 so that the vibration transmitted from the vibration transmitter is not attenuated.

The stock solution injected into the cell chamber 3 is
At this time, the liquid droplets 7 are vibrated by the vibration transmitted from the horn 6, preferably, by a pulse-like waveform of an aligned rectangular wave of ultrasonic waves, and cut into a uniform size.
And fall. Since the stock solution is cut for each pulse, a quantity corresponding to the vibration frequency is generated. For example, if the frequency is 10 kHz, 10,000 droplets 7 are generated per second per one hole of the nozzle 12, and the number obtained by multiplying this by the number of holes of the nozzle 12 is generated per second. Will be done. The frequency is determined by the particle size of the spherical particles to be produced.

FIG. 3 shows the nozzle plate 13, and FIG. 4 is an enlarged view of the nozzle section. The nozzle plate 13 has a disk shape, and the nozzles 12 are arranged in a row on the nozzle plate 13 so as to draw concentric circles. The diameter D ₁ of the array circle of the nozzles 12 is the diameter of a circle obtained by projecting a concentric circle having a size obtained by reducing the diameter D ₂ of the tip surface of the horn 6 having a cylindrical shape by 90% onto the opposed nozzle plate 13. It is the size included in.

[0029] Table 1 shows the results in the production experiment of solder balls, in which examined the ratio between the diameter D ₂ of diameter D ₁ and the front end surface of the array circle, the relationship between the accuracy of the ball. The accuracy of a ball is represented by the uniformity of the size of the balls and the sphericity of the ball as measured by the measurement ratio of the vertical and horizontal dimensions of one ball. The experimental results show that D
It can be seen that the performance difference appears 90% as a boundary in a ratio of ₁ / D _2. Further, it can be seen that if the arrangement circles of the nozzles 12 are within the range of the 90% circle, excellent accuracy can be obtained even when the circles are not concentric with the projection circle on the tip surface of the horn 6.
However, there is no positive meaning in not being concentric, and concentric arrangements that are easy to manufacture are usually employed.

[0030]

[Table 1] The shape of the nozzle 12 is a funnel shape in which a conical hole opening upward and a straight hole connected to the lower end thereof are combined so that the undiluted solution flows smoothly and smoothly. The opening angle α of the cone of the conical hole portion is formed in the range of 60 ° to 150 °. This is also confirmed from a solder ball manufacturing experiment, and the outline thereof is shown in Table 2. Table 2 shows the effect of the opening angle α on the accuracy of the ball, and as a result, differences appear in the dimensional uniformity.

[0031]

[Table 2] The length h of the straight hole in the straight hole portion of the nozzle 12 is 0.5 times the diameter d of the straight hole as the minimum size for realizing uniform droplet generation. Is set in a range up to three times the diameter d. The thickness H of the nozzle plate 13 ranges from 0.3 mm, which is the minimum thickness at which the nozzle plate itself does not excite itself due to vibration, to 5 mm, which is the maximum thickness at which good droplets can be stably obtained. Is set.

As the material of the nozzle plate 13, that is, directly the inner surface of the hole of the nozzle 12, stainless steel, cemented carbide, ceramics, or the like, or general steel, stainless steel, cemented carbide, or the like is used. Inorganic substances are made by chemical vapor deposition using either
Alternatively, one coated in one or more layers by physical vapor deposition is used. These materials are appropriately selected depending on the material used as the stock solution, the quality and precision required for the spherical particles, the cost aspect of the present manufacturing apparatus, and the like. Incidentally, Table 3 shows the relationship between the material of the nozzle plate 13 and the accuracy of the manufactured ball in a solder ball manufacturing experiment.

[0033]

[Table 3]

[0034]

According to the present invention, there is provided an apparatus for producing spherical particles, which is produced by dropping a liquefied stock solution into droplets, and according to the present invention, the arrangement, shape, material, and conduit of nozzles and nozzle plates. The purpose of the present invention is to prevent the clogging of the stock solution, improve the wettability, prevent the nozzle from rusting, extend the life of the nozzle, etc. so that the material and horn material can be selected and set appropriately. Droplets having a uniform size can be produced stably, and the spherical particles obtained by solidifying the droplets are spherical particles having excellent dimensional accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an entire apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of the cell chamber of FIG.

3A and 3B show the nozzle plate of FIG. 1, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along line AA.

FIG. 4 is an enlarged view of a nozzle portion of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Raw material tank 3 Cell chamber 4 Pump 5 Vibration transmitter 6 Horn 7 Droplet 8 Electrode 12 Nozzle 13 Nozzle plate D ₁ Diameter of array circle of nozzle D ₂ Diameter of tip surface of horn H Thickness of nozzle plate d Diameter of straight hole h Straight hole length α Opening angle

Claims (6)

[Claims] 1. A cell chamber in which a material of a spherical particle to be produced is liquefied and injected, and a vibration transmitter for applying vibration to a stock solution injected into the cell chamber. A nozzle is formed in a nozzle plate serving as a bottom surface of the cell chamber, and the undiluted solution flowing out of the nozzle is cut off by vibration through a horn extending from a vibration transmitter to drop as droplets, In a spherical particle manufacturing apparatus in which spherical particles having a uniform size are mass-produced by being solidified during dropping, a nozzle formed in the nozzle plate is provided with a horn centered on an axis of the horn. An apparatus for producing a spherical particle, wherein a 90% reduced surface at the tip is disposed in a projection plane onto a nozzle plate. 2. The nozzle has a funnel shape in which a conical hole opening upward and a straight hole connected to a lower end thereof are combined, and the conical hole has a cone opening angle of 60 ° to 150 °. The straight hole has a length of 0.5 to 3 times the diameter of the straight hole, and the thickness of the nozzle plate is 0.3 mm to 5 mm. The apparatus for producing spherical particles according to claim 1, wherein: 3. The apparatus for producing spherical particles according to claim 1, wherein the nozzles are arranged on the nozzle plate so as to draw a circle orbiting in a line. 4. The nozzle plate is made of stainless steel,
It is characterized by being formed of either cemented carbide or ceramics, or by using one of general steel, stainless steel, cemented carbide or ceramics as a base material and coating it with one or more inorganic substances. An apparatus for producing a spherical particle according to any one of claims 1 to 3. 5. A cell chamber in which the material of the spherical particles to be produced is liquefied and injected, and a vibration transmitter for applying vibration to the stock solution injected into the cell chamber. A nozzle is formed in a nozzle plate serving as a bottom surface of the cell chamber, and the undiluted solution flowing out of the nozzle is cut off by vibration through a horn extending from a vibration transmitter to drop as droplets, In a manufacturing apparatus for spherical granules in which spherical granules having a uniform size are mass-produced by being solidified during dropping, a conduit for leading a stock solution from a raw material tank to the cell chamber is a flexible heat-resistant pipe. An apparatus for producing spherical particles, characterized by being formed by: 6. A cell chamber in which the material of the spherical particles to be produced is liquefied and injected, and a vibration transmitter for applying vibration to the stock solution injected into the cell chamber. A nozzle is formed in a nozzle plate serving as a bottom surface of the cell chamber, and the undiluted solution flowing out of the nozzle is cut off by vibration through a horn extending from a vibration transmitter to drop as droplets, An apparatus for manufacturing a spherical particle, wherein a spherical particle having a uniform size is mass-produced by solidifying during dropping, wherein the horn is formed of ceramics.