JP3425050B2 - Equipment for manufacturing spherical particles - Google Patents

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 from a molten stock solution of metal, various resins, and the like. More specifically, the liquefied stock solution is made into droplets and cooled. Thus, the present invention relates to improvement of the cooling process of droplets in an apparatus adapted to produce spherical particles.

[0002]

2. Description of the Related Art There are several methods for producing spherical particles made of metal or various resins. For example, in the prior art for mass-producing solder balls, in addition to the method of casting by pouring into a mold, solder wire After mechanically cutting the oil, there is a method of melting it in the upper high temperature part of the high temperature heat transfer medium oil with a heat gradient and hardening it in the lower low temperature part, and further spray dryer method, tumbling granulation method, atomizing method, etc. Seems to have been adopted. Since these manufacturing methods are widely known techniques in the past, in actual manufacturing, details are accumulated as know-how of the manufacturing company, and there are many parts that are not made public. In such a situation, the present inventors have created a method for mass-producing spherical particles uniformly and with high accuracy based on an idea completely different from the above-mentioned conventional technology, and regarding its basic idea, Published in some magazines ("Boundary" April 1994 issue).

The outline of the contents described in this magazine is introduced below. First, the solution is pumped up from the tank containing the raw material solution and injected into the cell chamber. The cell chamber has a cylindrical shape and its bottom surface is closed by a disc. A through hole is formed in this disk to form a nozzle, and the solution sent to the cell chamber is extruded from this nozzle. that time,
The solution flowing out from under the nozzle has one of the following three forms. One of them is a droplet 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 is in the middle, where the solution is in the laminar flow region and has a columnar and stable flow immediately after flowing out of the nozzle. This is called a liquid column. It has been known that the flow velocity that creates this state is expressed as a function of the surface tension of the solution, the diameter of the nozzle, and the density of the solution, and it is not so difficult to select the conditions for the laminar flow. The solution that has become a liquid column is also naturally cut off at that point and drops as droplets.

If the cutting that occurs at the tip of the liquid column occurs at the same timing, uniform droplets will be formed, but when left to stand naturally, they are usually irregular. In order to cut it uniformly, a vibration transmitter is incorporated in the cell to force the liquid to shake. Since the surface of the vibration transmitter in the cell quivered, the solution itself quivered in a certain cycle, and the solution was evenly cut at the same timing. Dabora is Rayleigh (Ra)
We have succeeded in creating uniform droplets by vibrating at a frequency called the maximum unstable frequency in an inviscid fluid, which is the subject of Yleight).

The present inventors have succeeded in calculating the frequency at which the effluent is evenly cut. The details of the calculation formula are omitted here, but they are expressed as a function of the velocity of the liquid column and the diameter of the nozzle, and according to the calculation, if the diameter of the particle is small, such as 1 mm to 30 μm, the vibration is generated. The number is approximately 10 Hz to 100 kHz. The low frequency region is the normal sound wave region, and the frequency when making small particles is the ultrasonic wave region.

Since the solution of molten metal or the like can be dropped as uniform droplets by the method as described above, the droplets should be naturally cooled to form uniform spherical particles. . However, in actuality, it was confirmed that the droplets ejected from the nozzle were indeed droplets having uniform particles, but the particles obtained on the floor were not uniform.
This is because the air resistance in the course of falling causes a change in the falling speed of the particles, causing coalescence of the particles that have approached each other. To prevent this, an electrode was placed at the tip of the nozzle and applied to the liquid column. This is charged by electrostatic induction, and droplets that have been cut to a uniform size and charged are repelled by electrostatic repulsion when the distance between the droplets approaches, and fall without coalescence. . During the fall, it solidifies due to air cooling and drying, forming uniform spherical particles.

The above is the outline of the article described in the magazine, and FIG. 3 shows the general configuration of this manufacturing apparatus. In the figure, the solution stored in the raw material tank 1 is injected into the cell chamber 3 through the conduit 2 by the high temperature and high precision pump 4. A tip of a horn 6 extending from the vibration transmitter 5 is built in the cell chamber 3, and a droplet 2 cut into a uniform size by a vibrating action from a nozzle bored on the bottom surface of the cell chamber 3.
It becomes 2 and falls. The droplet 22 is applied by an electrode 23 arranged below the cell chamber 3, solidifies as a spherical particle during falling while being stored in the collection container 13 while avoiding coalescence of the droplets. .

[0008]

SUMMARY OF THE INVENTION The present invention relates to the stroke of a liquid drop after it has fallen from a nozzle of a manufacturing apparatus as described above. That is, the production method according to the conventional technique described above, the stock solution of the spherical particles is not obtained by high temperature, for example, a stock solution obtained by slurrying, more suitable, from the stock solution When making uniform granules, the particles are dropped into the air with the aim of solidifying by drying rather than cooling. Even if the undiluted solution is obtained by melting, it can be produced by a similar method regardless of the quality of the spherical particles, but the problem at this time is that the droplets are at a high temperature so It was necessary to take a long fall distance, and there were alterations caused by high temperatures such as the formation of an oxide film on the surface of the finished spherical particles, and this oxide film deteriorated the sphericity of the particles. There are problems.

[0009]

The present invention has been made in view of the above problems. First, the material of the spherical particles to be produced is liquefied at a high temperature in advance by melting or the like. This manufacturing device basically has a cell chamber, a vibration transmitter,
It is composed of a nozzle plate on the bottom of the cell chamber, a gas chamber arranged below the nozzle plate, and a liquid container arranged below this gas chamber. The undiluted solution injected into the cell chamber is transmitted from a vibration transmitter. It is excited by the vibration. Nozzles are formed in the nozzle plate, and when the stock solution flows out from the nozzle, it is cut into droplets having a uniform size by vibrating action and drops. The droplets pass through a gas chamber whose inside is formed in an antioxidation atmosphere and fall to the liquid container without touching oxygen on the way. The liquid container is filled with the heat medium liquid, and the liquid droplets that have entered the heat medium liquid are cooled and solidified as spherical particles.

According to a second aspect of the present invention, the antioxidant atmosphere in the gas chamber is formed by filling it with an inert gas. According to a third aspect of the present invention, the heat carrier liquid is a heat carrier liquid having a temperature gradient in which the upper part has a high temperature and the lower part has a low temperature. Further, according to claim 4, a heating medium oil having at least two layers, in which a heating medium oil excellent in oxidation resistance under high temperature is arranged on an upper part of the heating medium liquid and a highly viscous heating medium oil is arranged on a lower part, The inside of the liquid container is formed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An undiluted solution melted at a high temperature is subjected to an oscillating action from a vibration transmitter, cut into droplets having a uniform size, and drops, so that it is solidified into spherical particles by liquid cooling. However, at this time, shutting off the intermediate space up to the heat medium liquid from oxygen as an atmosphere for preventing oxidation is because an oxide film is formed on the surface of the droplet to change its quality, and thus the shape accuracy is deteriorated. This is to prevent this. The antioxidant atmosphere can be created relatively easily by filling it with an inert gas, and specifically, gases such as argon, helium, nitrogen, and hydrogen can be used.

By the way, as described in the prior art, the spherical granules that can be manufactured by air cooling are dropped in order to prevent the droplets from coalescing and becoming uneven in size during dropping. Immediately after that, an electrode was arranged and charged by electrostatic induction so that the droplets repel each other. However, in the present invention, the droplet is dropped into the heat medium liquid without disposing the electrode. This is because one of the functions of the heat medium liquid is utilized, and a liquid film is formed on the surface of the liquid droplets to prevent the liquid droplets from coalescing. The second action of the heat medium liquid is that the drop speed of the liquid droplets in the heat medium liquid becomes slower than that in the air, so that the distance required for cooling can be shortened accordingly. Of course, since it is in the heat medium liquid, no oxide film is formed.

In order to prevent the quality of the droplets entering the heating medium liquid from changing due to the rapid cooling, the upper part has a high temperature and the lower part has a low temperature. It is recommended to use the medium liquid. If the upper high temperature portion is set to be equal to or slightly higher than the temperature of the droplet in the cell chamber, the temperature change of the droplet is suppressed to a small extent, which is most effective in preventing alteration.

If the heat medium oil is used as the heat medium liquid and it is composed of two or more layers of heat medium oil, the cooling efficiency can be further improved. That is, by disposing a heat carrier oil having excellent oxidation resistance at high temperatures on the upper portion, deterioration of the oil agent is suppressed and the life of the oil agent is extended. Further, by arranging a low-viscosity, high-viscosity heat medium oil in the lower part, the drop speed of the liquid droplets can be further delayed, and the time required for cooling can be gained. Therefore, the drop distance can be shortened, and the height of the entire manufacturing apparatus can be set low. In such a configuration, generally, the specific gravity of the high-temperature oxidation-resistant heat carrier oil is smaller than that of the highly viscous heat carrier oil, and even if they are in the same liquid container, they are naturally separated and stored vertically. So it can be easily obtained.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the basic construction of an embodiment of the present apparatus for producing spherical particles. In the figure, the raw material tank 1 stores a stock solution liquefied by melting the material of the spherical particles to be manufactured. This stock solution is injected into the cell chamber 3 through the conduit 2. There are several methods for injecting the stock solution, such as a method for extruding by utilizing the pressure of gas, but in this case, the high temperature and high precision pump 4 is adopted as a drive 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 the tip thereof is built in. A gas chamber 7 is arranged below the cell chamber 3,
The gas chamber 7 is filled with the inert gas through the conduit 9 drawn from the gas cylinder 8. Below the gas chamber 7 is a liquid container 1
0 is arranged, and the heating medium liquid 11 is filled therein. Here, the gas chamber 7 forms a tubular body, the upper end of the tubular body is in close contact with the cell chamber 3, and the lower end of the tubular body is arranged so as to enter the heating medium liquid 11. Outside air does not enter. In addition, the lower end of the liquid container 10 is gradually narrowed into a tubular shape,
It is closed by a valve 12 incorporated in this portion. The spherical particles produced according to the method described below and settled at the lower end of the liquid container 10 are stored in the recovery container 13 and recovered by opening the valve 12.

FIG. 2 is an enlarged sectional view of the cell chamber 3. The cell chamber 3 is a body 14 formed by combining discs and cylinders with flanges, which are parts, and each part is integrally fastened with a bolt 15. A nozzle plate 17 having a nozzle 16 is provided on the bottom surface of the cell chamber 3 and is sandwiched by a packing 18 for preventing liquid leakage. It should be noted that the nozzle 16 has a nozzle plate 17
It consists of many holes arranged in a circle on the disc surface. A 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, unevenness is formed between the upper part of the cell chamber 3 and the flange of the horn 6, and an O-ring 19 is incorporated in the uneven part to leak the stock solution. Is being prevented. It is also necessary to seal the joints between the components of the body 14 of the cell chamber 3, and an O-ring 20 is incorporated in the lower portion of the cell chamber 3.

One end of the conduit 2 is screwed to the side surface of the main body 14, and the stock solution pumped up from the raw material tank 1 is injected into the cell chamber 3 from the conduit 2 through the through hole 21. The injected undiluted solution will flow out from the nozzle 16, but at this time, it is vibrated by the vibration emitted from the horn 6, preferably an ultrasonic aligned rectangular wave pulse-like waveform and cut into a uniform size. Then, the liquid drops 22 come to fall. Since the undiluted solution is cut every pulse, a quantity corresponding to the vibration frequency is generated. For example, at a frequency of 10 kHz, 10,000 holes 22 are generated per second for each hole of the nozzle 16,
A quantity obtained by multiplying this by the number of holes of the nozzle 16 is generated in one second. The frequency depends on the particle size of the spherical particles to be produced.

The droplet 22 passes through the gas chamber 7 filled with the inert gas and fills the liquid container 10 with the heat carrier liquid 1.
Since it enters into No. 1, it is not exposed to the outside air and oxidation is prevented. Droplet 2 that has entered the heat medium liquid 11
Although 2 is cooled during the fall and solidifies as spherical particles, since it is in the heat medium liquid 11, it is not oxidized here either. Further, since the liquid film protects the droplets, coalescence of the droplets does not occur, and the particle diameters do not become uneven.

The heating medium liquid 11 is provided with a temperature gradient such that the upper part has a high temperature and the lower part has a low temperature. This is to prevent alteration or deformation of the spherical particles due to rapid cooling, and specifically, the upper periphery of the liquid container 10 may be heated by a heater or the like (the heater is not shown). Further, since the liquid drops drop in the heat medium liquid 11, the drop resistance is larger than that in the air, and since the liquid drops 22 drop slowly over time, the drop distance until the liquid cools and solidifies can be shortened. .

One of the experiments conducted by the present inventors will be introduced here. In a solder ball manufacturing experiment as shown in Table 1, the temperature of the solder solution in the cell chamber at this time was about 240 ° C.
On the other hand, when the temperature of the upper part of the heat medium liquid 11 (specifically, heat medium oil is slightly higher) is about 270 ° C, it is more than one of about 240 ° C which is equivalent to the temperature of the solder solution. It has excellent sphericity expressed by the measurement ratio of vertical and horizontal dimensions with respect to the granules. Also, the sphericity of about 240 ° C, which is equivalent to the temperature of the solder solution, is more sphericity than that of the lower temperature of about 210 ° C. It turned out to be excellent. The uniformity of the size of the finished particles was good under all the three conditions tested.

[0023]

[Table 1] The heat medium liquid 11 has a two-layer structure in which the heat medium oil having excellent oxidation resistance at high temperature is arranged in the upper part and the low viscosity high-viscosity heat medium oil is arranged in the lower part, thereby acting as the heat medium oil. Can be exhibited more efficiently. That is, since the upper heat carrier oil suppresses deterioration of itself by oxidation, the life of the heat carrier oil is extended. The viscosity of the lower heat carrier oil further slows down the drop speed of the droplet 22.
Therefore, the drop distance until the droplets 22 become spherical particles and solidify can be shortened, and the height of the entire manufacturing apparatus can be designed to be low.

[0024]

EFFECTS OF THE INVENTION According to the apparatus for producing spherical particles according to the present invention, since the droplets are prevented from coming into contact with the air until they are solidified, an oxide film is formed on the surface of the spherical particles. Such alterations can be prevented. Further, since it enters the heating medium liquid having a temperature gradient and is gradually cooled, it becomes possible to mass-produce uniform and homogeneous spherical particles. Since the falling speed is slowed by the heat medium liquid, the falling distance is short, so that the height of the entire manufacturing apparatus can be designed to be low. By using the heat medium oil as the heat medium liquid and selectively arranging the heat medium oil according to its properties and arranging them in layers, the life of the heat medium oil can be extended, the efficiency can be improved, and the manufacturing apparatus can be made more compact.

[Brief description of drawings]

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

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

FIG. 3 is a schematic diagram showing a configuration of an entire apparatus which is an example of the related art.

[Explanation of symbols] 1 raw material tank 3 cell room 4 pumps 5 Vibration transmitter 6 horn 7 gas chamber 8 gas cylinders 10 liquid containers 11 Heat medium liquid 16 nozzles 17 nozzle plate 22 droplets

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-227043 (JP, A) JP-A-48-68474 (JP, A) JP-A-49-127898 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B05B 1/00-1/36 B01J 2/00-2/30 B06B 3/00

Claims (4)

(57) [Claims] 1. A cell chamber configured to liquefy and inject a material of spherical particles to be produced, and a vibration transmitter for vibrating the stock solution injected into the cell chamber. A nozzle is formed in the nozzle plate that is the bottom of the cell chamber, and the undiluted solution flowing out from the nozzle is cut by vibration by a vibration transmitter and drops as a droplet, which is solidified during the drop. In an apparatus for producing spherical particles in which uniform spherical particles are mass-produced, a gas chamber is provided below the nozzle plate to create an oxidation-preventing atmosphere inside, and a liquid container is provided below the gas chamber. An apparatus for producing spherical particles, characterized in that the heating medium liquid is filled in the container, and the droplets falling from the nozzle can enter the heating medium liquid without coming into contact with oxygen. 2. The apparatus for producing spherical particles according to claim 1, wherein an antioxidant atmosphere is formed by filling the interior of the gas chamber with an inert gas. 3. The production of spherical particles according to claim 1, wherein the heat carrier liquid is a heat carrier liquid having a temperature gradient in which the upper part has a high temperature and the lower part has a low temperature. apparatus. 4. The heat transfer medium liquid is formed of at least two layers in which a heat transfer medium liquid having excellent oxidation resistance at high temperature is arranged in an upper part and a high viscous heat transfer liquid is arranged in a lower part. 4. The apparatus for producing spherical particles according to claim 1, claim 2 or claim 3.