JPH0857634A - Method and apparatus for manufacturing fine metal balls - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method and an apparatus for producing fine metal spheres capable of producing stable and uniform fine metal spheres for forming bumps. A gas supply means for supplying a predetermined gas 22 from a vertically arranged furnace core tube 10 and an inlet 21 provided at a lower portion of the furnace core tube 10 and raising a carrier gas 23 in the furnace core tube 10. 20 and a carrier gas flow 2 near the bottom of the furnace core tube 10.
A metal wire piece supply means 30 for supplying the metal wire piece 1 to 3
And a heating means 4 arranged at an appropriate position of the furnace core tube 10 so that the metal wire piece 1 can be heated to at least its melting point temperature.
0, and the metal wire piece 1 placed at a proper position above the heating means 40.
The cooling means 50 is adapted to cool the furnace, and the recovery means 60 arranged on the upper part of the furnace core tube 10.

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 manufacturing fine metal balls, that is, metal bumps used for bonding an electrode portion of a semiconductor element to the outside such as a metal wiring.

[0002]

2. Description of the Related Art For example, TAB (Tape Automated Bondi)
ng) When using a tape to manufacture a semiconductor device,
The leads of the AB tape and the electrode parts of the semiconductor element can be joined by metal bumps made of fine metal balls.
According to the TAB method, the electrode portion of the semiconductor element or the TAB
In this method, bumps are formed in advance on either of the lead tip portions of the tape, and then the electrode portion and the lead tip portion are overlapped with each other via the bumps to join the two.

As a method of manufacturing a bump used for such bump bonding, a plating method or a transfer method, which has been the mainstream in the past, is known. However, in the case of the plating method, there are problems that the equipment is large and the metal composition used as the bump is restricted. Therefore, in order to eliminate the inconvenience in the plating method or the like, according to the method of manufacturing a bump of this type disclosed in, for example, Japanese Patent Application Laid-Open No. 4-66601, a metal wire piece cut to a fixed length is placed in a vertical furnace. It is allowed to fall freely, is heated to a temperature equal to or higher than the melting point of the metal during the fall to be spheroidized by the action of surface tension, and the sphere is solidified and taken out from the furnace bottom.

In the case of the method of free-falling the metal wire piece as described above, the size of the metal wire piece actually used is 20 mm in diameter.
Since it is extremely fine and lightweight with a length of about 30 μm and a length of about 0.15 to 0.40 mm, metal wire fragments scatter due to convection generated inside the furnace core tube heated above the melting point of the metal, or to each other. There was a risk of touching and coalescing. Then, further, in the vertically arranged furnace core tube, the metal wire piece is dropped on the air current or gas flow flowing from the upper part to the lower part of the furnace core tube, and the metal wire piece is heated to a temperature equal to or higher than the melting point of the metal. A method for producing fine metal spheres has been proposed in which a metal wire piece is made spherical by melting.

[0005]

However, in such a conventional method for producing fine metal spheres, when the metal wire piece is further miniaturized, especially in the vicinity of the heating part for melting the metal, the furnace core The effect of the rising airflow inside the tube became remarkable, and it was difficult to drop the metal wire piece stably. As a result, it has been difficult to make the shapes, sizes, etc. of the fine metal spheres to be formed sufficiently uniform.

In view of the above situation, it is an object of the present invention to provide a method of manufacturing fine metal spheres and a manufacturing apparatus therefor capable of always stably and uniformly producing fine metal spheres for forming bumps.

[0007]

A method for producing fine metal balls according to the present invention comprises a step of forming a carrier gas flow flowing from a lower part to an upper part in a furnace core tube arranged in a vertical direction, and A step of supplying a metal wire piece to the carrier gas stream at a lower portion, a step of heating the metal wire piece in the carrier gas stream to at least its melting point temperature, and melting the heated metal wire piece. Thus, it is provided with a step of spheroidizing and a step of cooling and recovering the spheroidized fine metal spheres.

Further, in particular, in the method of the present invention, there is a step of controlling the flow rate of the carrier gas so that the heated metal wire piece can be made ellipsoidal or aspherical by melting.

The apparatus for producing fine metal spheres of the present invention supplies a predetermined gas from a furnace core tube arranged in the vertical direction and an inlet provided in the lower part of the furnace core tube, and carries a carrier gas in the furnace core tube. And a metal wire piece supplying means for supplying a metal wire piece to the carrier gas flow near the lower part of the furnace core tube, and a metal wire piece arranged at an appropriate position of the furnace core tube. Heating means adapted to heat the piece to at least its melting point temperature, cooling means arranged in an appropriate place above the heating means and capable of cooling the metal wire piece, and arranged on an upper part of the furnace core tube And the collected collecting means.

[0010]

According to the present invention, a predetermined gas is supplied at the lower part of the furnace core tube by the gas supply means to form a carrier gas flow flowing from the lower part to the upper part of the furnace core tube. The metal wire piece supplied to the carrier gas flow by the metal wire piece supply means is heated by the heating means during the ascending in the furnace core tube. Then, the melted metal wire pieces are spheroidized by the action of the surface tension. Next, it is solidified by being cooled by the cooling means, and is collected at the upper part of the furnace core tube by the collecting means.

In the present invention, since the direction of the carrier gas flow in the furnace core tube and the direction of the ascending air current generated by the heating in the heating portion are the same (ascending), the metal wire piece is extremely supplied to the carrier gas flow. Easier to do. Moreover, since the direction of the ascending air flow of the heating unit and the direction of the carrier gas flow are the same, the air flow state in the furnace core tube can be stabilized. As a result, metal wire pieces that are melted in such a carrier gas and further cooled are
When spheroidized, the shape, size, etc. are stable, and extremely uniform fine metal spheres can be obtained.

Further, according to the present invention, the flow rate of the carrier gas supplied by the gas supply means can be controlled, and the rising speed of the metal wire piece carried by the carrier gas flow can be adjusted to adjust the metal wire. The conditions for melting the piece or for subsequent solidification can be varied. As a result, it is possible to make the fine metal spheres elliptical or non-spherical by melting and solidifying the heated metal wire pieces. That is, it is possible to control the shape of the fine metal spheres to be formed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the method for manufacturing a fine metal sphere and the manufacturing apparatus therefor according to the present invention will be described below with reference to FIGS. FIG. 1 shows the overall configuration of a manufacturing apparatus for fine metal balls according to an embodiment of the present invention. This apparatus supplies a predetermined gas 22 from a furnace core tube 10 arranged in a vertical direction and an inlet 21 provided at a lower portion of the furnace core tube 10, and a gas supply means for raising a carrier gas in the furnace core tube 10. 20, a metal wire piece supply means 30 for supplying the metal wire piece 1 to the carrier gas flow near the lower part of the furnace core tube 10, and a metal wire piece 1 arranged at an appropriate position on the furnace core tube 1 at least. A heating means 40 capable of heating to the melting point temperature, a cooling means 50 arranged at an appropriate position above the heating means 40 and capable of cooling the metal wire piece 1, and a heating means 40 arranged at an upper portion of the furnace core tube 10. And a recovery means 60.

The furnace tube 10 is made of a material such as quartz glass and has a size of, for example, an inner diameter of 100 mm and a length of 500 mm. Inlet 21 at the bottom of the core tube 10
As the gas supplied from, an inert gas such as argon gas is preferably used, but it is also possible to use air. The gas supply means 20 stably supplies the gas 22, but a flow rate control valve (not shown) is provided at an appropriate position before the inlet 21. The flow rate of the gas 22 can be controlled via this flow rate control valve.

In the metal wire piece supply means 30, the furnace core tube 1
Inlet 3 for a pipe-shaped supply pipe 31 provided near the lower part of 0
The metal wire piece 1 is supplied from 2. The inlet 32 is set at a position slightly higher than the inlet 21 of the gas supply means 20, and the supply pipe 31 can have a venturi structure as shown in the figure. A predetermined gas such as argon gas or air is preferably introduced into the supply pipe 31, and the ventilated portion of the supply pipe 31 can suck up the metal wire piece 1 from the container 33 by the gas flow.

In the heating means 40, the furnace core tube 10 is surrounded by a tubular body 41 made of a carbon material. A high frequency induction coil 42 is further arranged around the cylindrical body 41. The high-frequency induction coil 42 is connected to a power supply circuit (not shown) or the like, and is capable of high-frequency heating from around the furnace core tube 10 to at least a temperature equal to or higher than the melting point of the metal wire piece 1. The heating temperature of the high frequency induction coil 42 is appropriately set to a desired temperature.
Can be maintained.

In the cooling means 50, a cooling pipe 51 surrounds the furnace core tube 10, and the cooling water is circulated through the cooling tube 51 to cool the furnace core tube 10. The temperature, flow rate, and the like of the cooling water flowing in the cooling pipe 51 can be controlled, and therefore, the cooling temperature for the furnace core tube 10 can be appropriately set to a desired temperature.

The recovery means 60 comprises a recovery head 61 and a recovery container 62. The recovery head 61 has a large number of gas injection nozzles 63 as shown in the drawing at the top and in the vicinity of the top. Further, a discharge port 64 for discharging the fine metal balls 2 toward the recovery container 62 is opened at a gas ejection destination from the gas ejection nozzle 63. The recovery container 62 is configured as a donut-shaped water tank filled with cooling water 65, as shown in FIG. 2, for example. The collection container 62 is
As shown in FIG. 3, it may be divided into a plurality of relatively small water tanks (four tanks in this example), and in this case, the outlet 64 of the recovery head 61 is branched so as to correspond to each water tank. The structure.

Next, description will be given of a case where the fine metal sphere 2 is formed from the metal wire piece 1 by using the fine metal sphere manufacturing apparatus configured as described above. First, the gas 22 is supplied from the inlet 21 by the gas supply means 20, thereby forming the carrier gas flow 23 flowing from the lower part to the upper part of the furnace core tube 1. The inlet 3 of the supply pipe 31 by the metal wire piece supply means 30
The metal wire piece 1 is supplied from 2. And carrier gas flow 2
The metal wire piece 1 supplied to 3 is heated to a temperature equal to or higher than the melting point by the heating means 40 while the metal wire piece 1 is being raised.

The melted metal wire piece 1 has a large surface tension in this melted state, and thus is spherical.
When the carrier gas flow 23 is placed in this spheroidized state and further rises in the furnace core tube 1, it is solidified by being cooled by the cooling means 50 next. When the metal balls 2 thus formed reach the recovery head 61, they are recovered into the recovery container 62 via the discharge port 64 by the gas injection from the gas injection nozzle 63.

Now, according to the invention, a carrier gas stream 2 formed in particular by a gas 22 supplied through an inlet 21.
3 and the ascending air current 24 generated by the heating of the heating means 40.
Since the directions of 1 and 2 both face upward, that is, they coincide with each other, the metal wire piece 1 can be easily supplied to the carrier gas flow 23. Further, since the rising airflow 24 generated by the heating means 40 is in the same direction as the carrier gas flow 23, it does not disturb the flow of the carrier gas flow 23 and the furnace core tube 1
The airflow condition in 0 can be stabilized.

Therefore, the metal wire piece 1 melted in the carrier gas flow 23 has a stable shape, size and the like when it is spheroidized, and it is possible to obtain extremely uniform fine metal spheres 2. Further, since the rising airflow 24 itself near the heating means 40 can be used for transporting the metal wire piece 1, the introduction port 21
The amount of the gas 22 supplied from can be effectively reduced.

Further, by adjusting the flow rate of the carrier gas stream 23 formed by the gas supply means 20, the rising speed of the metal wire piece 1 carried by the carrier gas stream 23 can be adjusted. Thereby, the heated metal wire piece 1
The shape of the fine metal spheres 2 can be controlled by changing the conditions for melting or solidifying thereafter. In other words, not only a perfect spherical shape but also an ellipsoidal shape or an aspherical shape (raindrop shape, streamline shape, etc.) is possible. The fine metal spheres 2 formed in an ellipsoid or the like are extremely effective in securing the bump height.

Here, FIG. 4 shows a modification of the device of the present invention. In this device, in the recovery means 160, the recovery pipe 161 and the recovery container 16 connected to the upper part of the furnace core tube 10 are connected.
2 is provided. The recovery pipe 161 is curved from the top to the bottom as in the illustrated example, and the tip of the recovery pipe 161 holds the minute metal spheres 2
A discharge port 164 for discharging to the recovery container 162 filled with the cooling water 163 is opened. Also, the cooling means 15
Reference numeral 0 has a plurality of cooling pipes 151 to 154 surrounding a part (upper part) of the furnace core tube 10 and the recovery pipe 161. In addition,
Other configurations are basically the same as the configurations of the above-described device (FIG. 1).

In this apparatus, as in the case of the above-mentioned example, the metal wire piece 1 melted in the furnace core tube 10 is put on the carrier gas flow 23 in a spheroidized state so as to flow inside the furnace core tube 1. To rise. Then, the fine metal spheres 2 solidified by being cooled by the cooling means 150 are conveyed in the recovery pipe 161, and are recovered in the recovery container 162 via the discharge port 164.

Also in this case, since the metal wire piece 1 has a stable shape, size and the like when it is formed into a spherical shape, it is possible to obtain extremely uniform fine metal balls 2. And especially in this example, the structure around the recovery means 160 can be made relatively simple.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to the specific numerical values and the like described in these examples, and various modifications and the like are possible within the scope of the present invention.

[0028]

As described above, according to the present invention, the carrier gas flow of the metal wire piece in the furnace core tube is formed as an ascending airflow, and this carrier gas flow and the direction of the ascending airflow generated by the heating of the heating means. Since the metal wire pieces are made to coincide with each other, the supply of the metal wire pieces is facilitated, and the shape,
It is possible to obtain extremely uniform fine metal spheres with stable size and the like. Further, there is an advantage that the shape of the fine metal spheres to be formed can be controlled by adjusting the flow rate of the carrier gas flow.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the overall configuration of an apparatus for producing fine metal balls according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a recovery container according to the apparatus for producing fine metal balls of the present invention.

FIG. 3 is a perspective view showing a modified example of the collection container according to the present invention.

FIG. 4 is a vertical cross-sectional view showing a modified example of the apparatus for producing fine metal balls of the present invention.

[Explanation of symbols]

 1 metal wire piece 2 micro metal sphere 10 core tube 20 gas supply means 21 introduction port 22 gas 24 carrier gas 30 metal wire piece supply means 31 supply pipe 32 introduction port 33 container 40 heating means 41 cylinder 42 high-frequency induction coil 50, 150 Cooling Means 51 Cooling Pipes 60,160 Recovery Means 61 Recovery Heads 62,162 Recovery Containers 63 Gas Injection Nozzles 64,164 Discharge Ports 65 Cooling Water

Claims (3)

[Claims] 1. A step of forming a carrier gas flow flowing from a lower part to an upper part in a furnace core tube arranged in a vertical direction, and supplying a metal wire piece to the carrier gas flow at a lower part of the furnace core tube. A step of heating the metal wire piece in the carrier gas flow to at least its melting point temperature, spheroidizing the heated metal wire piece by melting, and spheroidizing the fine metal spheres. And a step of cooling and collecting the fine metal spheres. 2. A step of controlling a flow rate of the carrier gas, wherein the heated metal wire piece is melted,
The method for producing fine metal spheres according to claim 1, wherein the metal spheres can be made elliptical or non-spherical. 3. A vertically arranged furnace core tube, and a gas supply means for supplying a predetermined gas from an inlet provided at a lower portion of the furnace core tube to raise a carrier gas in the furnace core tube, A metal wire piece supply means for supplying a metal wire piece to the carrier gas flow in the vicinity of the lower portion of the furnace core tube, and a metal wire piece arranged at an appropriate position of the furnace core tube and heating the metal wire piece to at least its melting point temperature. A heating means for obtaining, a cooling means arranged at an appropriate place above the heating means, for cooling the metal wire piece, and a collecting means arranged at an upper portion of the furnace core tube. An apparatus for producing fine metal balls, which is characterized in that