JP2001035874A - Method for formation of low-melting point metal electrode and forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-melting point metal electrode forming method and device which stably enagles the collective arrangement of low-melting point metal electrodes on an electric element also in a small-diameter solder balls and can form solder bumps with high accuracy, at low cost and at a high working efficiency. SOLUTION: An arrangement board 1 has liquid drop formation holes in its surface, has through holes 3 penetrating the board until the backside of the board 1 in the bottoms of the liquid drop formation holes, has a molten metal feeding means for feeding a molten low-melting point metal on the backside of the board 1 and has small holes 6 in a cover 4 made to closely adhere to the surface of the board 1, then the molten metal 11 is fed from the molten metal feeding means through the holes 3 to form molten metal drops 10 in each liquid drop formation hole. After the drops 10 are formed, the cover 4 is removed from the board 1, and the surface of an electric element is made to approach to the surface of the board 1, whereby the drops 10 are made to adhere to the electrode parts of the element.

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 forming a low-melting-point metal electrode for simultaneously forming a low-melting-point metal electrode on a large number of electrode portions of an electric element. Ball grid array), CSP
The present invention relates to a method and an apparatus for forming a solder bump formed on an electrode portion of a semiconductor element in (chip size package) or the like.

[0002]

2. Description of the Related Art Electric devices such as semiconductor devices include:
It is necessary to electrically connect a large number of electrodes on the element and an external circuit. When a BGA or CSP method is used as a connection method, it is necessary to form solder bumps by raising solder on a large number of electrode portions on the electric element.

[0003] As a method of forming a solder bump on an electrode portion on an electric element, a solder plating method, a solder paste printing method, a vacuum deposition method, a ball bump method and the like are conventionally known.

[0004] The solder plating method is a method of forming a solder bump by depositing solder on an electrode portion on an electric element by an electrolytic plating method. In this method, there is a problem that the height of the solder bumps formed on the electrode portions varies, and it is necessary to take environmental measures for the manufacturing equipment, thereby increasing the equipment cost.

[0005] The solder paste printing method is a method in which cream solder is printed on an electric element electrode portion, and a solder bump is formed on the electrode portion by reflow. in this way,
There is a problem that the height of the solder bumps varies, and there is also a problem that the solder bumps cannot be coped with when the pitch for forming the solder bumps is narrow.

[0006] The vacuum evaporation method is a method of forming solder bumps by coating solder on an electric element electrode portion using vacuum evaporation means. This method requires a large-scale vacuum deposition apparatus, and has a problem that the manufacturing cost is increased.

In the ball bump method, a small-diameter solder ball is prepared in advance, the solder ball is arranged on an electrode portion of an electric element, heated, the solder ball is welded to the electrode portion, and reflowed, thereby soldering the electrode portion. Form bumps. When arranging the solder balls on the electrode portions of the electric element, an arrangement device having suction holes for sucking the solder balls corresponding to the positions of the electrode portions is prepared, and the solder balls are sucked into the suction holes of the arrangement device. Then, by releasing the suction after the arrangement device is brought into close contact with the electric element while sucking the solder balls, it is possible to mount a large number of solder balls at a time on the electric element. According to this method, it has become possible to easily and quickly form a semiconductor bump having several hundreds of solder bumps. Further, since it is possible to manufacture a solder ball having a small diameter variation, the solder bump formed by the ball bump method can keep the height accuracy of the bump high. Further, the equipment cost can be kept low as compared with the above-mentioned solder plating method or vacuum evaporation method.

[0008]

Recently, the density and miniaturization of semiconductor devices have been further advanced, and the number of electrode portions having solder bumps required by one semiconductor device is on the order of hundreds to thousands. Has been reached. When the solder bump is formed by a ball bump, the size of the solder ball is as follows:
Small-diameter solder balls having a diameter of 200 μm or less have been used.

In the method in which the solder balls are sucked into the suction holes of the arraying device by the ball bump method, the smaller the diameter of the solder balls, the smaller the diameter of the suction holes inevitably.
The suction force for sucking the solder ball also decreases in proportion to the square of the suction hole diameter. On the other hand, a self-sucking force is sometimes applied between the solder balls collected on the tray before the suction or between the solder balls and the arrangement device. Due to the self-sucking force, the surplus solder balls are attracted to the arrangement device after the solder balls are sucked into the suction holes. Excessive solder balls that have been adsorbed must be removed by blowing a gas stream or applying vibration to the arrangement device. On the other hand, in a small-diameter solder ball having a diameter of 200 μm or less, the suction force of the solder ball by the suction hole is small as described above. Will be eliminated. Therefore, when the diameter of the solder ball is reduced as described above, it becomes difficult to arrange the solder ball by the conventional ball bump method.

[0010] The present invention has solved the above-mentioned problems and has a diameter of 20 mm.
Even small-diameter solder balls of 0 μm or less can be stably arranged in batches on electrical elements, and the height accuracy of solder bumps is kept high, equipment costs and manufacturing costs are low, and soldering efficiency is high. An object of the present invention is to provide a method and an apparatus for forming a low-melting-point metal electrode capable of forming a bump.

[0011]

That is, the gist of the present invention is as follows. (1) A method of forming a low melting point metal electrode in which a plurality of electrode portions 13 of an electric element 12 are formed at the same time. The array plate 1 has a droplet forming hole 2 on the surface thereof, and a bottom portion of the droplet forming hole 2 has a through hole 3 penetrating to the rear surface of the array plate 1. Molten metal supply means 7 is provided on the arrangement plate 1 corresponding to the position where the low melting point metal electrode 15 is to be formed on the element 12, and the rear surface side of the arrangement plate 1 is adapted to melt and supply the low melting point metal. First, the lid 4 is brought into close contact with the surface of the array plate 1, and the lid 4 has pores 6 at positions corresponding to the respective droplet forming holes 3 for allowing gas in the droplet forming holes to escape. The molten metal 1 is supplied from the molten metal supply means 7 through the through hole 3.
1 to form a molten metal droplet 10 in each droplet forming hole, remove the lid 4 from the arrangement plate 1 after the formation of the molten metal droplet, and then bring the surface of the electric element 12 close to the surface of the arrangement plate 1 The molten metal droplet 10 is moved by the electrode portion 13 of the electric element 12.
A method for forming a low-melting-point metal electrode, comprising: (2) The molten metal supply means 7 is a molten metal container 8 arranged on the back surface side of the array plate 1, and melts into each droplet forming hole 2 through the through hole 3 by pressurizing the molten metal container 8. (1) wherein the metal 11 is supplied.
3. The method for forming a low-melting-point metal electrode according to item 1. (3) After the molten metal is supplied into the droplet forming hole 2, the pressure of the molten metal 11 in the molten metal supply means 7 is released, and the molten metal 11 and the molten metal droplet 1 stored in the molten metal supply means are released.
The method for forming a low-melting-point metal electrode according to the above (1) or (2), characterized in that a gap between 0 and 0 is divided in the through hole 3. It is.

(4) A low melting point metal electrode forming apparatus for simultaneously forming the low melting point metal electrodes 15 on a large number of electrode portions 13 of the electric element 12, wherein the forming apparatus includes an arrangement plate 1, a lid 4 and a low melting point metal electrode. The arrangement plate 1 has droplet forming holes 2 on its surface, and penetrates through the bottom of the droplet forming holes 2 to the back surface of the arrangement plate 1. The drop forming holes 2 are arranged on the array plate 1 corresponding to the positions where the low melting point metal electrodes 15 are to be formed on the electric element 12. Are provided at the positions corresponding to the holes 6 for allowing the gas in the droplet forming holes to escape.
The molten metal 11 is supplied from the molten metal supply means 7 through the through hole 3 to form the molten metal droplet 10 in each droplet forming hole 2. Next, the lid 4 is removed and the surface of the electric element 12 is brought close to the surface of the arrangement plate 1 so that the molten metal droplet 10 is attached to the electrode portion 13 of the electric element 12. (5) The molten metal supply means 7 has a molten metal container 8 and a pressurizing means 9 arranged on the back surface side of the array plate 1, and the pressurizing means 9 pressurizes the inside of the molten metal container 8 to form a through-hole. 3. The apparatus for forming a low-melting-point metal electrode according to the above (4), wherein the molten metal 11 is supplied into each droplet forming hole 2 through 3. (6) The through-hole 3 has a small diameter, and after the molten metal 11 is supplied into the droplet forming hole 2, the pressure of the molten metal in the molten metal supply means 7 is released, whereby the molten metal supply means 7 is released.
The apparatus for forming a low-melting-point metal electrode according to the above (4) or (5), wherein a space between the molten metal 11 and the molten metal droplet 10 stored in the inside is divided in the through hole 3.
It is.

According to the present invention, instead of arranging solid low melting point metal balls produced in advance by an arrangement device and arranging them on electric elements, droplet forming holes 2 are arranged on an arrangement plate 1 and the droplets are formed. The formation hole 2 is an electrode portion 1 on which a bump on the electric element 12 is to be formed.
3 is formed in a molten state in the droplet forming hole 2 to form a low-melting-point metal droplet 10, and the formed droplet is directly attached to the electrode portion 13 on the surface of the electric element. The biggest feature is that the low melting point metal electrode 15 is formed.

The gist of the present invention will be described with reference to FIGS. The array plate 1 has a molten metal supply means 7 such as a molten metal container 8 on the back side thereof, and is heated to a temperature sufficient to melt the target low melting point metal. A predetermined amount of molten metal for forming a droplet 10 is supplied from the molten metal supply means 7 into the droplet forming hole 2 through a small diameter through hole 3 provided at the bottom of the droplet forming hole 2. The supplied molten metal becomes a droplet 10 in the droplet forming hole due to its own surface tension.

When the pressure of the molten metal in the molten metal supply means 7 is released or reduced by making the diameter of the through hole 3 sufficiently small, the droplet 1 formed in the droplet forming hole 2 is released.
0 and the molten metal 11 in the molten metal supply means 7 can be separated in the through hole 3. Due to the surface tension of the droplet 10, even if the molten metal in the molten metal supply means is decompressed, the droplet 10 does not return to the through hole 3, and the droplet 10 becomes independent in the droplet forming hole 2, It is separated from the molten metal in the molten metal supply means.

In the present invention, when the molten metal is supplied from the molten metal supply means 7 into the droplet forming holes 2, the lid 4 is adhered to the arrangement plate 1 so as to be in contact with the arrangement plate 1. The lid 4 has pores 6 at positions corresponding to the respective droplet forming holes 2. Lid 4
When is closely attached to the array plate 1, a closed space having a constant internal volume is formed in each droplet forming hole 2. When the molten metal 11 is supplied from the molten metal supply means 7 into the droplet forming hole 2, the gas in the closed space is eliminated through the fine holes 6, and the space is filled with the molten metal. When a predetermined amount of molten metal necessary for forming the droplet 10 is filled in the droplet forming hole, the molten metal reaches the entrance of the pore 6 of the lid 4 and the supply of the molten metal into the space is started. Stop. For this reason, a uniform size droplet 10 with little variation can be formed in each droplet forming hole 2 on the array plate 1.

After the droplets 10 are formed in the respective droplet forming holes 2, the lid 4 is removed, and the droplets 10 are attached to the electric element 12, whereby the low melting point alloy electrode 15 is applied to the electric element 12.
To form A flux 14 is applied in advance to the electrode portion 13 of the electric element 12, and the surface of the electric element 12 approaches the arrangement plate 1 so that the electrode portion 13 corresponds to the position of each droplet forming hole 2 of the arrangement plate 1. Let it. Since the electrode portion 13 coated with the flux 14 has good wettability with the molten metal, the droplet 1
When 0 comes into contact with the electrode portion 13, the droplet adheres to the electrode portion, and reflows to form a low melting point metal electrode (bump) 15 on the electrode portion.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Solder is most commonly used as a low melting point metal used for forming an electrode in the present invention. In addition to solder, a silver alloy can also be used.

The shape of the droplet forming holes 2 on the array plate 1 and the shape of the lid 4 will be described with reference to FIGS. The size of the droplet 10 formed in the droplet forming hole is determined by the space volume in the droplet forming hole 2 when the lid 4 is brought into close contact with the array plate 1. On the other hand, after the droplet is formed, the droplet is
It is necessary that the apex of the formed droplet 10 protrudes from the surface of the array plate 1 in order to adhere to the surface of the array plate 1. Therefore, it is effective to provide the concave portion 5 in the lid 4 and form the droplet 10 in a space in which the concave portion 5 of the lid 4 and the concave portion of the droplet forming hole 2 are combined. Thus, when the lid 4 is removed after the droplet is formed, the top of the formed droplet 10 projects from the droplet forming hole 2 to the surface of the array plate.

In order for the supplied molten metal to become droplets 10 in the droplet forming holes, the materials of the arrangement plate 1 and the lid 4 must be materials that do not wet the molten metal. When solder is used as the molten metal, if stainless steel, titanium, or ceramics is used as the shape of the arrangement plate 1 and the lid 4, these materials do not have wettability with the molten solder. Can be.

The rear surface side of the array plate 1 (the side opposite to the opening side of the droplet forming holes) is formed in a container shape, and the molten metal having a low melting point is filled in the container 8 to form the molten metal supply means 7. A pressurizing means 9 using means such as a piston is added to the container 8. The molten metal supply means 7 may divide the large number of droplet forming holes 2 of the array plate 1 into several blocks and independently supply the low melting point metal for each block.

At the bottom of the droplet forming hole 2, there is provided a through hole 3 penetrating to the rear surface of the array plate 1, and the through hole 3 forms a droplet with the molten metal 11 in the container 8 which is the molten metal supply means 7. The hole 2 is in communication. By compressing a piston as a pressurizing means 9 of the container 8, the molten metal in the container is pressurized as shown in FIG. Supplied to The supplied molten metal forms a droplet 10 in the droplet forming hole due to its own surface tension.

After the supply of the molten metal to the droplet forming hole 2 is completed, when the pressurization of the molten metal in the container 8 is released, the inner walls of the droplet forming hole 2 and the through hole 3 do not have wettability with the molten metal. Therefore, the molten metal in the through hole and the droplet in the droplet forming hole are separated from each other by the surface tension of the molten metal. In order to surely separate the molten metal together with the release of the pressure, the smaller the diameter of the through hole 3 is, the better. When the molten metal is solder, the diameter of the through hole 3 is set to 1/3 or less of the diameter of the droplet forming hole 3,
For example, when the diameter of the droplet forming hole is 100 μm, by setting the diameter of the through hole 3 to 32 μm or less, the molten metal can be reliably separated. If the pressure of the molten metal 11 in the container 8 is positively reduced after the formation of the droplets, the molten metal can be more reliably divided.

As shown in FIG. 3 (b), when the molten metal is supplied, the droplet forming hole 2 must be closed with a lid 4 and the gas in the closed space must be removed together with the supply of the molten metal. The pores 6 are provided. If the pores 6 are provided so as to penetrate the lid 4, the gas in the space is released to the outside air through the pores 6.

When the space is filled with the molten metal, the top of the formed droplet 10 reaches the pore 6 of the lid 4 as shown in FIG. The diameter of the pores 6 must be set so that the pressurized molten metal does not leak out through the pores. When the molten metal is solder, the diameter of the pore 6 is set to 1/3 or less of the diameter of the recess 5, for example, when the diameter of the recess 5 is 100 μm, the diameter of the pore 6 is set to 32 μm or less. Until the space is filled with the molten solder, the solder does not enter the pores.

When the supply of the molten solder is stopped, the stop timing can be controlled by presetting the piston stroke amount corresponding to the volume of the entire space.

It is preferable that the lid 4 is provided with the pores 6 and desirably the recess 5. Arrangement plate 1 after droplet formation
When the lid 4 is detached from the solder, the solder is spheroidized due to the effect of its own surface tension, so that the solder droplets rise from the droplet forming holes 2 on the surface of the array plate 1. The amount (height) of the liquid droplets rising from the surface of the array plate 1 can be controlled by adjusting the volume of the concave portion 5 of the lid 4.

By making the solder droplets rise from the droplet forming holes 2 on the surface of the arrangement plate 1 in this manner, the electric element 1 on which the low melting point metal electrode 15 such as a solder bump is to be formed is formed.
When approaching the arrangement plate to the arrangement plate, the molten metal droplet can be brought into contact with the electrode portion without fail.

In order to maintain the molten state of the molten metal in the molten metal supply means and the molten metal droplets formed in the droplet forming holes, the arrangement plate 1, the lid 4, and the molten metal supply means 7 are all provided with the molten metal. Must be maintained at a temperature equal to or higher than the melting point.

In the electric element 12 where the low melting point metal electrode 15 such as a solder bump is to be formed, the drawing of the electrode portion 13 using a conductive material such as copper is completed in advance at the position where the bump is to be formed. . Prior to the formation of the low-melting metal electrode 15, a flux 14 is applied to the electrode portion 13 of the electric element 12.
The flux is applied to the entire surface of the electric element 12. Desirably, flux coating is performed on the electrode portion 13 by screen printing or the like using a mask.

When the lid 4 is removed as shown in FIG. 3E with the liquid drop forming hole opening side of the array plate 1 facing upward, the molten metal droplet 10 is held in each liquid drop forming hole. Next, FIGS. 2 and 3
As shown in (f), with the surface having the electrode portion 13 of the electric element 12 coated with the flux 14 facing downward, each electrode portion is made to approach the array plate 1 so as to face the corresponding droplet forming hole.
The electrode portion 13 coated with the flux 14 is
As shown in FIG. 3 (g), the molten metal droplet 10 comes into contact with the electrode 13 and the electrode 1
3 and a bump is formed. Next, the electric element 12 is lifted and separated from the array plate 1 to
As shown in (h), the bumps on the electric element are cooled and solidified to complete the low melting point metal electrode (bump) 15.

In the process from the formation of the molten metal droplet to the formation of the low melting point metal electrode (bump) on the electric element, it is preferable that the atmosphere in which the molten metal comes into contact is a non-oxidizing atmosphere. For that purpose, the arrangement plate 1, the lid 4, the electric element 1
It is preferable to carry out the treatment by arranging 2 in a closed non-oxidizing atmosphere.

In the present invention, the diameter of the droplet formed can be reduced by reducing the volume of the space formed by the concave portion of the droplet forming hole 2 and the concave portion 5 of the lid 4. Diameter 200 which was difficult with the conventional ball bump method
In the present invention in which droplets having a size of μm or less are individually formed in each droplet forming hole, the droplets can be formed without any problem.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrode portion 13 on a semiconductor substrate has a diameter of 120 μm.
The present invention is applied to a case where a total of 30,000 solder balls (molten solder droplets) are collectively mounted to form a solder bump. In this case, the semiconductor substrate is an 8-inch diameter silicon wafer itself. This will be described in detail with reference to FIGS.

The array plate 1 made of stainless steel is provided with a total of 30,000 droplet forming holes 2 at positions corresponding to the positions of the electrode portions 13 on the semiconductor substrate. The droplet forming hole 2 has a diameter of 100
A through hole 3 having a diameter of 32 μm is provided from the bottom of the droplet forming hole 2. The rear surface side of the array plate 1 is a molten solder container 8, and the container capacity is 157.
0 cm ³ . The molten solder in the container is supplied from the through hole 3 into the droplet forming hole 2 by pressing with the piston 16.

The lid 4 made of stainless steel has a droplet forming hole 2
Is provided at a position corresponding to. The recess 5 has a diameter of 1
A pore 6 having a diameter of 32 μm, which is 00 μm, has a depth of 60 μm, and penetrates to the surface on the opposite side of the lid 4.

The arrangement plate 1, the molten solder container 8, and the lid 4 have an electric heating mechanism and are heated to 220 ° C., so that the molten state of the solder can be maintained.

First, the lid 4 is brought into close contact with the arrangement plate 1, then the piston 16 is operated to press the molten solder container 8, and the molten solder in the molten solder container 8 is injected into each droplet forming hole 3.
Each droplet forming hole 3 is filled with a fixed amount of molten solder. When the lid 4 is separated from the array plate 1, a droplet 10 having a diameter of 120 μm is formed in each droplet forming hole 3.

On the semiconductor substrate on which the low melting point metal electrode (solder bump) 15 is to be formed, a circuit including the electrode portion 13 is formed in advance, and a flux is applied to the entire surface of the semiconductor substrate. Next, the semiconductor substrate is caused to approach the array plate 1 on which the droplets are formed, and the droplets 10 are brought into contact with the respective electrode portions 13 on the semiconductor substrate. The droplet 10 adheres to the electrode portion 13 to form the low-melting metal electrode 15.

The low-melting metal electrodes 15 were formed on a total of 200 semiconductor substrates. Low melting point metal electrode 1
Abnormality in which No. 5 was not formed, and abnormality in which solder adhered to an unexpected position on the semiconductor substrate did not occur at all.

[0041]

According to the present invention, even when a fine solder ball having a diameter of 200 μm or less is mounted on an electrode portion of a semiconductor element, it is formed into droplets, thereby achieving a highly reliable package without mounting trouble. Is now possible. Since it is possible to mount by the method of quantitatively cutting out from the molten metal as droplets, it is possible to keep the size of the solder ball uniform even in electric elements that require minute solder bumps, It has become possible to form a solder bump with high accuracy and little variation in height. In addition, since the ball system is used, equipment costs and manufacturing costs can be reduced, and a large number of products can be manufactured in a short time because batch mounting is possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an apparatus for forming a low-melting-point metal electrode including an arrangement plate and a lid according to the present invention.

FIG. 2 is a cross-sectional view showing an apparatus for forming a low melting point metal and an electric element according to the present invention.

3A and 3B are partial cross-sectional views illustrating a method for forming a low-melting-point metal electrode according to the present invention, wherein FIG. 3A shows an arrangement plate before droplet formation, FIG. ) Shows the state where the space between the droplet forming hole and the concave portion of the lid is filled with molten metal, and (d)
Shows the situation where the filling of the molten metal is completed, (e) shows the situation where the lid is removed after the formation of the droplet, (f) shows the situation where the electric element is approaching the array plate on which the droplet has been formed, and (g) shows the situation where the liquid is formed. It is a figure which shows the state in which the droplet in the droplet formation hole adhered to the electrode part of the electric element, and (h) shows the state in which the formation of the low melting point metal electrode in the electrode part of the electric element was completed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 arrangement plate 2 droplet forming hole 3 through hole 4 lid 5 concave portion 6 pore 7 molten metal supply means 8 molten metal container 9 pressurizing means 10 molten metal droplet (droplet) 11 molten metal 12 electric element 13 electrode section 14 flux 15 Low melting point metal electrode 16 Piston

Claims (6)

[Claims] 1. A method for forming a low-melting-point metal electrode on a large number of electrode portions of an electric element at the same time, wherein the array plate has droplet-forming holes on its surface, At the bottom of the hole has a through hole penetrating to the back surface of the array plate, the droplet forming holes are arranged on the array plate corresponding to the position where a low melting point metal electrode is to be formed on an electric element, On the back side of the arrangement plate, there is provided a molten metal supply means for melting and supplying a low melting point metal, and firstly, a lid is brought into close contact with the surface of the arrangement plate, and a position of the lid corresponding to each of the droplet forming holes. Has holes for allowing gas in the droplet forming holes to escape, and then supplies molten metal from the molten metal supply means through the through holes to form molten metal droplets in each droplet forming hole. After the molten metal droplets are formed, the lid is removed from the arrangement plate, and then the electric element is placed on the surface of the arrangement plate. A method for forming a low-melting-point metal electrode, comprising: adhering the molten metal droplet to an electrode portion of an electric element by approaching a surface. 2. The molten metal supply means is a molten metal container disposed on the back side of the array plate, and pressurizes the molten metal container to cause molten metal to enter each droplet forming hole through the through hole. 2. The method according to claim 1, wherein
3. The method for forming a low-melting-point metal electrode according to item 1. 3. After the molten metal is supplied into the droplet forming hole, the pressure of the molten metal in the molten metal supply is released, and the molten metal stored in the molten metal supply is mixed with the molten metal droplet. The method for forming a low-melting-point metal electrode according to claim 1, wherein the space is divided in the through hole. 4. A low melting point metal electrode forming apparatus for simultaneously forming low melting point metal electrodes on a large number of electrode portions of an electric element, said forming apparatus melting and supplying an arrangement plate, a lid and a low melting point metal. The arrangement plate has a droplet forming hole on its surface, and a bottom portion of the droplet formation hole has a through hole penetrating to the back surface of the arrangement plate, The formation holes are arranged on the arrangement plate corresponding to the positions where the low melting point metal electrodes are to be formed on the electric element, and the gas in the droplet formation holes is provided at the position of the lid corresponding to each of the droplet formation holes. The molten metal supply means is disposed on the back side of the arrangement plate, and the lid is brought into close contact with the arrangement plate to supply molten metal from the molten metal supply means through the through hole. To form a molten metal droplet in each droplet forming hole, and then remove the lid and remove the array plate. An apparatus for forming a low melting point metal electrode, wherein the molten metal droplet is attached to an electrode portion of the electric element by bringing the surface of the electric element close to the surface. 5. The molten metal supply means has a molten metal container and a pressurizing means arranged on the back side of the arrangement plate, and pressurizes the molten metal container by the pressurizing means to form the through-hole. The apparatus for forming a low-melting-point metal electrode according to claim 4, wherein the molten metal is supplied into each of the droplet forming holes through the molten metal. 6. The molten metal supply means according to claim 6, wherein said through hole has a small diameter, and after the molten metal is supplied into said droplet forming hole, the pressure of said molten metal in said molten metal supply means is released. The apparatus for forming a low-melting-point metal electrode according to claim 4 or 5, wherein a gap between the stored molten metal and the molten metal droplet is divided in the through hole.