JPH104099A - Method and apparatus for forming bumps - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming bumps at a high production efficiency with more reduced number of steps than that in the conventional plating method of forming the bumps. SOLUTION: The method of forming solder bumps 27 on electrode pads 3a of a semiconductor chip 3 comprises step 1 of placing a mask 25 having holes 26 facing electrode pads 3a and heating the mask 25 at a temp. higher than the m.p. of a solder 12 for forming solder bumps 27, step 2 of feeding the solder 12 heated at its m.p. onto the pads 3a through the holes 26 of the mask 25, step 3 of squeegeeing the mask 25 with the solder 12 and step 4 of removing the mask from the chip 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a BGA,
The present invention relates to a method and an apparatus for forming a bump on an electrode pad of a chip component such as a bare chip.

[0002]

2. Description of the Related Art A conventional plating method is generally used for forming solder bumps on electrode pads of a semiconductor chip.
However, in the plating method, it is necessary to form a resist pattern for protecting a wiring pattern other than the electrode pads by a chemical process so that a solder film is formed only on the electrode pads.

On the other hand, as another bump forming method, there is a cream solder printing method. In this method, as shown in FIG. 8, a metal mask A is closely placed on an electrode (not shown) formed on a substrate B, and squeezing is performed by a cream solder S on the metal mask A. By doing so, the bumps D are formed on the electrodes. Such a bump D is formed in a hemispherical shape by a reflow process by heating.

[0004]

However, in order to carry out the bump forming method by the conventional plating method,
A chemical process consisting of a process of applying a thick resist pattern that protects the wiring pattern other than the electrode pads, exposing and developing the opening pattern of the electrode pads, and a plating process. There is a problem that equipment is required.

On the other hand, the bump formation by the cream solder printing method involves the opening position accuracy of the metal mask A, the opening size, the sectional shape of the opening, the smoothness of the inner wall of the opening, the adhesion of the metal mask A to the substrate B, the squeegee rubber hardness. , Squeegee flatness, squeegee abrasion resistance, squeegee speed control, filling of cream solder S into opening of metal mask A, plate dropout, shape stability after printing (drip resistance), etc. Even when the pitch of the bumps is 0.5 mm or less, it is extremely difficult to perform the bump formation with high accuracy and stability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bump capable of easily and accurately forming a solder bump on an electrode pad without using a chemical process. An object of the present invention is to provide a forming method and an apparatus therefor.

[0007]

In order to achieve the above object, the present invention provides a method for forming a solder bump on a plurality of electrode pads provided on a chip component. A first step of mounting the mask having the openings facing the pair of electrode pads and heating the mask to a temperature higher than the melting point of the solder to be the solder bumps; A second step of supplying the solder heated to the melting temperature from the opening of the mask heated to a temperature higher than the melting point of the solder on the electrode pad; and supplying the solder from the opening of the mask after the second step. And a fourth step of removing the mask from the chip component after the third step. Method.

[0008] A second aspect of the present invention is characterized in that the chip component of the first aspect is a semiconductor chip. A third aspect of the present invention is characterized in that the chip component of the first aspect includes a semiconductor chip and a substrate on which the semiconductor chip is mounted.

According to a fourth aspect of the present invention, in the pump forming apparatus for forming solder bumps on a plurality of electrode pads provided on a chip component, a chip component holding means for mounting the chip component with the electrode pads facing upward, A mask having a plurality of openings opposed to the electrode pads, positioning the openings provided in the mask and the electrode pads corresponding to the openings, and setting the mask to a temperature higher than the melting point of the solder to be the solder bumps; Mask positioning means having a mask heating means for heating the solder serving as the solder bump, and heating the syringe to a melting temperature and a solder provided at one end of the syringe and heated to the melting temperature from the opening. Solder supply means having a needle for supplying on an electrode pad; and the need while holding the syringe. And a squeezing means for squeezing the mask supplied with solder from the opening by the needle. . A fifth aspect of the present invention is characterized in that the mask positioning means of the fourth aspect has a mask heating means for heating the mask to a temperature higher than the melting point of the solder.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment. FIG. 1 shows a bump forming method, and FIG. 2 shows an overall configuration of a bump forming apparatus. FIG. 3 is an enlarged view of a main part of the syringe 10 in the bump forming apparatus. FIG. 4 shows the mask positioning means 40. First, a bump forming apparatus will be described with reference to FIG. 2. Reference numeral 1 denotes a table. A mounting table 2 is provided on a part of the table 1, and a semiconductor chip 3 as a chip component is provided on an upper surface of the mounting table 2. Is installed. An X-axis rail 4 constituting an XY stage is provided on the table 1, and an X-axis drive unit 5 movable in the X direction is provided on the X-axis rail 4. The X-axis drive unit 5 is provided with a Y-axis rail 6, and the Y-axis rail 6 is provided with a Y-axis drive unit 7 that is movable in the Y direction.
Further, the Y-axis driving section 7 is provided with a Z-axis rail 8, and the Z-axis rail 8 is provided with a Z-axis driving section 9 which is movable in the Z direction. The syringe 1 is provided in the Z-axis drive unit 9.
0 is mounted, and this syringe 10
It is movable in the Y direction and is vertically movable with respect to the table 1. Thus, the X-axis rail 4, the X-axis driving unit 5, the Y-axis rail 6, the Y-axis driving unit 7, the Z-axis rail 8, and the Z-axis driving unit 9 constitute syringe positioning means.

The syringe 10 is, as shown in FIG.
Cylindrical solder container 10a containing molten solder 12
And an electric heater 10b for heating the solder 12 above the melting point of the solder 12 provided in the solder container 10a;
a needle 10c having a needle shape having an outer diameter of 2 mm and an inner diameter of 30 μm, for example, coaxially connected to the lower end of the solder container 10a, and discharging an appropriate amount of molten solder 12 from the needle 10c in a timely manner by adjusting the air pressure. And a discharge control unit 10d to be operated. The ejection control unit 10d is provided so as to form a bump described later in cooperation with a controller described later.

The Y-axis drive unit 7 is provided with a camera holder 18, and the camera holder 18 is provided with a television camera 19 as an imaging optical system for recognizing the semiconductor chip 3.

Further, the X-axis driving unit 5 and the Y-axis driving unit 7
And the Z-axis drive unit 9 are connected to a drive mechanism 20 such as a motor for independently driving them.
0 is connected to the controller 21. The controller 21 controls the drive control unit 22 that controls the drive mechanism 20 and the electric heater 14, and controls the temperature of the syringe 10 by, for example, 20
A temperature controller 23 for maintaining the temperature around 0 ° C. and a camera controller 2 for controlling the television camera 19 by recognizing an offset amount between the needle 13 and the center of the television camera 19.
4 are provided.

Further, as shown in FIG. 4, on the table 1, a mask positioning means 40 is provided. The mask positioning means 40 is connected to the periphery of the mask 25 and heats the mask 25 to a temperature higher than the melting point of the solder 12.
And a mask holding driving unit 4 such as a robot hand for positioning the mask 25 at a predetermined position while detachably holding the mask 25 via the mask heating unit 41.
2 and a mask control unit 43 for controlling the mask heating unit 41 and the mask holding drive unit 42 based on a preset work program. The mask control unit 43 controls to form a bump, which will be described later, in cooperation with the controller 21.

Further, on the table 1, a squeezing means 25a is provided. The squeegee includes a squeegee 12a (see FIG. 1) and a squeegee 12a.
The squeegee drive for positioning and driving the a and squeezing the mask 25 to which the molten solder 12 is supplied from the opening 26 by the needle 13 to remove excess solder and equalize the amount of the molten solder 12 to be the solder bump 27 Means 1
2b (see FIG. 2). The squeegee driving means 12b also performs processing described later according to the control signal of the controller 21.

As shown in FIG. 1, the semiconductor chip 3 has a large number of electrode pads 3a, and is mounted on the mounting table 2 with the electrode pads 3a facing upward. A mask 25 is provided on the upper surface of the semiconductor chip 3 by the mask positioning means 40 so as to face the gap g (for example, 100 to 300 μm) corresponding to the thickness of the electrode pad 3a. The mask 25 is a plate-shaped body made of, for example, glass, alumina, or a metal having poor adhesion to the molten solder 12, for example, tungsten, molybdenum, titanium, or the like. An opening having substantially the same shape as the electrode pad 3a is provided at a portion facing the electrode pad 3a. 26 are drilled. Thus, the opening 26
It is provided in a shape corresponding to the shape of the electrode pad 3a, and as shown in FIG. 5, one side is 100 μm to 200 μm.
Are arranged in a lattice at a pitch of 200 μm to 400 μm.

Although not shown, the bump forming apparatus of this embodiment includes an apparatus for automatically applying a flux onto the electrode pads 3a. Next, a method of forming solder bumps on the electrode pads 3a of the semiconductor chip 3 according to the embodiment of the present invention using the bump forming apparatus configured as described above will be described.

The semiconductor chip 3 is mounted at a predetermined position on the mounting table 2 with the electrode pads 3a facing upward. Next, FIG.
As shown in FIG. 3A, after a flux (not shown) is applied to the upper surface of the electrode pad 3a, the mask 25 is placed on the upper surface of the semiconductor chip 3 by the mask holding / driving unit 42 via the gap g. At the same time, the circular opening 26 of the mask 25 is positioned so as to face the electrode pad 3a. At this time, the mask 25 is heated by the energized mask heating unit 41 to, for example, about 200 ° C., which is higher than the melting point of the solder 12.

Next, the molten solder 1 is placed in the syringe holder 11.
The syringe 10 in which the two are accommodated is set, and the driving mechanism 20 is set.
The X-axis driving unit 5 and the Y-axis driving unit 7 are moved in the X and Y directions to position the syringe 10 and the television camera 18 on the mask 25 mounted on the semiconductor chip 3.

Then, the position of the opening 26 of the mask 25 is imaged by the television camera 18, the image at this time is captured, and a specific reference point (for example, based on the leftmost uppermost opening 26) in the captured recognition image. , TV camera 18
After the needle 13 offset by a certain distance from the opening 26 of the mask 25, the syringe 1 is moved by the driving mechanism 20 in the Z-axis direction by the Z-axis driving unit 9.
2 is lowered to approach the needle 13 and the opening 26 of the mask 25.

The offset of the needle 13 is adjusted before the solder bump forming step. That is, first, the molten solder 12 is dropped from the needle 13 onto a substrate having the same dimensions as the semiconductor chip 3. Next, the television camera 18 is moved to a dropping position of the molten solder 12 by a preset offset amount. Further, the distance between the drop position of the molten solder 12 and the television camera 18 is obtained as an offset error. The offset amount is updated so that the offset error is eliminated. The above operation is repeated until the offset error disappears.

The mask 25 by the television camera 18
Is performed every time the semiconductor chip 3 on which the solder bump is formed changes. Next, FIG.
As shown in (b), when the molten solder 12 in the syringe 10 is discharged through the needle 13 by the discharge control unit 10d, a fixed amount of the molten solder 12 is supplied to the electrode pad 3a through the opening 26. This operation is repeated to supply the molten solder 12 to many electrodes 3a of the semiconductor chip 3. However, since the mask 25 is heated to a temperature higher than the melting point of the solder, the supplied solder may be solidified. However, it is kept in a raised state on the electrode pad 3a (see FIG. 1B).

When the molten solder 12 has been discharged into all of the openings 26 of the mask 25, the portion that is raised from the openings 26 is removed, and the molten solder 12 filled in the openings 26 of the mask 25 is removed. As shown in FIG. 1 (c), squeegee 12a performs squeezing in order to make the amount of the ink uniform. At this time, the temperature of the mask 25 is higher than the melting temperature of the solder.

Further, the mask 2 after the squeezing is completed
5 is kept horizontal and raised by the mask holding / driving section 42 to separate it from the semiconductor chip 3 (see FIG. 1D), whereby the mask 25 is removed from the opening 26 of the mask 25 heated by the mask heating section 41. Molten solder 12
After cooling to a substantially hemispherical shape due to surface tension,
The solder bump 27 is formed (see FIG. 1E). After the formation of the solder bumps 27, the semiconductor chips 3 may be subjected to a reflow process at about 200 ° C. in a reflow furnace, so that the shape of the solder bumps 27 is again formed into a hemispherical shape.

As described above, according to the bump forming method of the embodiment of the present invention, the molten solder 12 is dropped one by one from the needle 13 onto the electrode pad 3a through the opening 26 of the mask 25 positioned on the semiconductor chip 3. Thus, since the solder bumps 27 are formed, the number of steps is reduced as compared with the formation of the solder bumps by the conventional plating method, and the production efficiency is increased. Further, even when the pitch of the bumps is 0.5 mm or less as compared with the conventional cream solder printing method, it is possible to form the bumps with higher precision.

Further, according to the bump forming apparatus of the embodiment of the present invention, the syringe 10 which is accurately positioned at the bump forming position by the syringe positioning means such as the X-axis driving unit 5, the Y-axis driving unit 7, and the Z-axis driving unit 9. Molten solder 1 contained in
2 is discharged from the needle 13 onto the electrode pad 3a through the opening 26 of the mask 25, so that an appropriate amount of the molten solder 12 can be reliably and efficiently supplied onto a desired electrode pad 3a. . Further, since the mask heating section 41 for heating the mask 25 is provided, it is possible to contribute to the formation of the smooth solder bump 27. Together with these effects, it is possible to form the solder bumps 27 having a desired shape reliably and efficiently.

According to the first embodiment, a method and an apparatus for forming a solder bump on an electrode pad of a semiconductor chip have been described. However, the method and apparatus for forming a solder bump on an electrode pad formed on a substrate are also described. Applicable.

That is, as shown in FIG. 6, in the case of a surface-arranged junction semiconductor package 30 such as a plastic ball grid array (P-BGA), the BGA substrate 3
1, a semiconductor chip 32 is mounted, and the semiconductor chip 3
2 and the BGA substrate 31 are electrically connected by wire bonding. Further, the semiconductor chip 32 is
Since the semiconductor package 30 is formed integrally with the GA substrate 31 by a resin mold 33, the semiconductor package 30 is inverted and the BG is formed as shown in FIG.
By placing the mask 25 on the A substrate 31 and making the opening 26 of the mask 25 face the electrode pad 34 formed on the BGA substrate 31, the solder bump 35 can be formed in the same manner.

[0029]

As described above, claims 1 to 3 of the present invention.
The method of forming a bump by forming a solder bump by dropping molten solder onto an electrode pad through an opening of a mask that is accurately positioned. The number of processes is smaller than that of, and the production efficiency is increased. Further, even when the pitch of the solder bumps is smaller than that of the conventional cream solder printing method, the shape of the solder bumps can be formed with high accuracy.

According to a fourth aspect of the present invention, the molten solder contained in the syringe, which is accurately positioned at the bump forming position by the syringe positioning means, is discharged from the needle onto the electrode pad through the opening of the mask. Therefore, it is possible to reliably and efficiently supply an appropriate amount of molten solder on a desired electrode pad. Further, since the mask heating section for heating the mask is provided, it is possible to prevent the molten solder discharged to the opening from being rapidly cooled and solidified, and to contribute to the formation of a smooth solder bump. Together with these effects, it is possible to form solder bumps having a desired shape reliably and efficiently.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a bump forming method according to a first embodiment of the present invention.

FIG. 2 is an exemplary perspective view showing the entire bump forming apparatus of the embodiment;

FIG. 3 is a cross-sectional view illustrating a main part of the syringe unit of FIG. 2;

FIG. 4 is a sectional view showing the mask positioning means of FIG. 2;

FIG. 5 is a plan view showing a main part of the mask of the embodiment.

FIG. 6 is an explanatory diagram of a semiconductor package according to a bump forming method according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of the bump forming method of the embodiment.

FIG. 8 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Semiconductor chip (chip part) 3a ... Electrode pad 10 ... Syringe 12 ... Molten solder 25 ... Mask 26 ... Opening 27 ... Solder bump

Claims (4)

[Claims] In a pump forming method for forming solder bumps on a plurality of electrode pads provided on a chip component, a mask having a plurality of openings is placed with the openings facing the pair of electrode pads. A first step of heating the mask to a temperature higher than the melting point of the solder that will become the solder bump; and a melting temperature on the electrode pad from the opening of the mask heated to a temperature higher than the melting point of the solder after the first step. A second step of supplying the solder that has been heated to above, a third step of squeezing the mask on which the solder has been supplied from the opening of the mask after the second step, and after the third step And a fourth step of removing the mask from the chip component. 2. The bump forming method according to claim 1, wherein the chip component is a semiconductor chip. 3. The bump forming method according to claim 1, wherein the chip component comprises a semiconductor chip and a substrate on which the semiconductor chip is mounted. 4. A pump forming apparatus for forming solder bumps on a plurality of electrode pads provided on a chip component, wherein: a chip component holding means for placing the chip component with the electrode pad facing upward; A mask having a plurality of openings facing each other, positioning the openings provided in the mask and the electrode pads corresponding to the openings, and heating the mask to a temperature higher than the melting point of the solder to be the solder bumps Mask positioning means having mask heating means, a syringe for containing the solder to be the solder bumps and heating to a melting temperature, and a solder provided at one end of the syringe and heated to the melting temperature is supplied from the opening to the electrode pad through the opening. Solder supply means having a needle for supplying the needle, A bump positioning device comprising: a syringe positioning means for positioning at a position facing an electrode pad to be supplied with solder; and a squeezing means for squeezing a mask supplied with solder from the opening by the needle. Forming equipment.