JP3185779B2 - Mounting method of conductive ball - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for mounting a conductive ball for forming a bump on an electrode of a work such as a chip or a substrate.

[0002]

2. Description of the Related Art In a process of manufacturing a work having a bump such as a flip chip, a method using a conductive ball such as a solder ball is known as a method of forming a bump (protruding electrode) on an electrode of the work. Also, as a method using conductive balls, the mounting head is moved up and down above the supply section of the conductive balls, so that a large number of conductive balls are picked up by the mounting head, and then the mounting head is moved above the workpiece. A method is known in which a plurality of conductive balls are collectively mounted on an electrode of a work by performing an up / down operation.

[0003]

However, in the above-mentioned conventional method, the mounting head is provided with an extra conductive ball at the supply portion of the conductive ball (in the present invention, this extra ball is referred to as an "extra ball"). ) Is easily picked up, and this extra ball is erroneously mounted on the work, resulting in a problem that a defective work is produced.

Accordingly, an object of the present invention is to provide a method of mounting a conductive ball, which can prevent an extra ball from being erroneously mounted on a work.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a conductive ball which is provided in a conductive ball supply section, is sucked into a suction hole formed in a lower surface of a mounting head, is picked up, and is mounted on a work. After the mounting head picks up the conductive ball, it detects extra balls adhering to the underside of the mounting head, and after the mounting head mounts the conductive ball on the work, Remaining balls adhering to the lower surface are detected.

According to the present invention, extra balls erroneously attached to the mounting head are detected, and only the conductive balls of the mounting head from which no extra balls are detected can be mounted on the work.

[0007]

(Embodiment 1) FIG. 1 is a side view of a conductive ball mounting apparatus according to Embodiment 1 of the present invention, and FIG.
And FIG. 3 are explanatory views of the transfer operation of the conductive ball, and FIG.
FIG. 5 is a perspective view of a detection unit of the extra ball, FIG. 5 is an explanatory diagram of an operation of detecting the extra ball, FIG. 6 is an explanatory diagram of a detection operation of the remaining ball, and FIG. 7 is a partially enlarged sectional view of a lower portion of the mounting head. It is.

In FIG. 1, reference numeral 1 denotes a solder ball as a conductive ball, which is stored in a container 2. Reference numeral 3 denotes a base on which the container 2 is placed. Vibration means for vibrating the container 2 and gas supply means for feeding gas into the container 2 are provided inside the base 3 to fluidize the solder balls 1 in the container 2. On the right wall of the container 2, a brush 4
Is projected upward. The container 2 and the base 3 constitute a supply unit for the solder balls 1.

In FIG. 1, reference numeral 10 denotes a work, which is clamped by a clamper 11 and positioned. The clamper 11 is supported by a column 13 erected on a base 12. The clamper 11, the base 12, and the support 13
This is the positioning part. A case 14 is provided between the container 2 and the work 10 as a collecting part of the solder ball 1. In FIG. 4, brackets 15 and 16 are provided upright on both sides of the case 14. The light emitting element 17 is mounted on the inner surface of the bracket 15, and the light receiving element 18 is mounted on the inner surface of the bracket 16 (see also FIG. 5). The light emitting element 17 and the light receiving element 18 are connected to a cable 19
Is connected to the detection unit 20 via the. The detection unit 20 is connected to the control unit 21. L is an optical path of light emitted from the light emitting element 17 to the light receiving element 18. The light emitting element 17 and the light receiving element 18 constitute an extra ball detecting means.

In FIG. 1, reference numeral 22 denotes a mounting head.
The mounting head 22 is held below the box 23. A motor 24 is provided above the box 23. The box 23 has built-in vertical movement means such as a feed screw driven by a motor 24.
When 4 is driven, the mounting head 22 moves up and down. As shown in FIG.
Are opened. The mounting head 22 is connected to a pneumatic unit (not shown). When the pneumatic unit is driven, the solder ball 1 is vacuum-adsorbed and held in the suction hole 25, and the solder ball is released by releasing the vacuum suction state. Drop 1

In FIG. 7, the suction hole 25 is formed with a tapered concave portion 25a capable of adsorbing only one solder ball 1. When the solder ball 1 is normally adsorbed, it is accommodated in the concave portion 25a. You. On the other hand, since the extra ball 1A is not accommodated in the concave portion and adheres to the lower surface 22a of the mounting head 22, a difference in height from the normally sucked solder ball 1 is ensured. In the conductive ball mounting apparatus of the first embodiment, the extra ball 1A can be detected and distinguished from the normally attracted solder ball 1 by utilizing the height difference between the normal solder ball 1 and the extra ball 1A. ing.

In FIG. 1, a box 23 is held on a horizontally long moving table 26 as moving means. The moving table 26 has a built-in feed screw mechanism. When the motor 27 is driven to operate the feed screw mechanism, the mounting head 22 moves between the container 2, the case 14, and the work 10 in the horizontal direction.

This conductive ball mounting apparatus is constructed as described above, and the operation will be described next. In FIG. 1, the mounting head 22 moves above the container 2 and performs a lowering / elevating operation there.
The solder ball 1 is vacuum-adsorbed and picked up. FIG.
Shows the lower part of the mounting head 22 from which the solder ball 1 has been picked up. As shown in the drawing, one solder ball 1 is vacuum-sucked to each suction hole 25. In FIG. 7, however, one extra conductive ball (extra ball) 1A is attached. . If the extra ball 1A is mounted on the work 10, the work 10 becomes defective. Therefore, the extra ball 1A must not be mounted on the work 10. The extra balls 1A are generated due to adhesion of solder balls due to static electricity, vacuum leakage of the suction holes 25, and the like.

In FIG. 1, the mounting head 22 picking up the solder ball 1 moves rightward toward the work 10 (see also FIG. 2). At this time, the mounting head 2
2 passes above the brush 4, and the upper end of the brush 4 slides on the solder ball 1 held on the lower surface of the mounting head 22. Among the solder balls shown in FIG. 7, the normal solder ball 1 which has been correctly vacuum-sucked directly to the suction hole 25 is strongly vacuum-sucked and held, so that it does not fall even when the brush 4 slides, but the extra ball 1A Is held by a weak force due to static electricity or the like. If the brush 4 is provided in the moving path of the mounting head and the brush 4 is slid in contact with the solder ball 1 as in the present embodiment, the extra ball 1A is transferred during the transfer of the solder ball 1 to the work 10.
Can be easily dropped and removed. In addition, brush 4
, The extra ball 1A dropped by the brush 4 can be collected in the container 2 as it is.

Next, the mounting head 22 passes between the light emitting element 17 and the light receiving element 18 as shown in FIG. FIG.
As shown in FIG. 7 and FIG. 7, the level of the mounting head 22 is
The normal solder ball 1 does not shield the optical path L from light, but the extra ball 1A protruding downward from the normal solder ball 1 is set to be shielded from light. Of course, the level of the mounting head 22 is controlled by driving the motor 24. As described above, the extra ball 1A can be slid and dropped by the brush 4, but the slidable drop is not always successful, and the extra ball 1A still remains as shown in FIGS. You may have. Such an extra ball 1A is detected by blocking the light path L.

As described above, when the extra ball 1A is detected, various methods are available, some of which will be described below. First, the first method is to stop the mounting head 22 above the case 14, and then operate the pneumatic unit (not shown) in the opposite direction, thereby causing the suction holes 25 to move.
All the solder balls 1 and the extra balls 1A held by the mounting head 22 are dropped into the case 14 and collected by releasing air from the nozzle or releasing the vacuum suction state. Then, the mounting head 22 is returned above the container 2, and the pickup operation is performed again.

In the second method, arrows Q1, Q in FIG.
2, the mounting head 22 is returned above the container 2 as shown by Q3, and is again moved above the brush 4 as shown by arrow Q4, so that the extra ball 1A is slid and dropped by the brush 4 again.

In the third method, the mounting head 22 is returned above the container 2 and the mounting head 22 is lowered so that the lower surface of the mounting head 22 rushes into the layer of the solder balls 1 stored in the container 2 in a large amount. In this state, the mounting head 22 is scrubbed in the lateral direction by driving the motor 27 in the forward and reverse directions, thereby forcibly swinging the extra ball 1A. As described above, the extra ball 1A can be removed by various methods.

The mounting head 22 from which the extra balls 1A have been removed moves above the work 10 in FIG. Then, the mounting head 22 descends and the solder balls 1
Is landed on the electrode of the work 10. Next, solder ball 1
When the vacuum suction state is released and the mounting head 22 is raised, the solder balls 1 are mounted on the electrodes of the work 10.
The work 10 on which the solder balls 1 are mounted is sent to a heating furnace (not shown), and the solder balls 1 are heated, melted and solidified to form bumps. In order to heat and melt the solder ball 1, a flux is required. The flux is applied to the lower surface of the solder ball 1 held on the lower surface of the mounting head 22 or the electrode of the work 10 by means not shown.

When the solder ball 1 is mounted on the work 10 as described above, the mounting head 2
2 returns above the container 2. FIG. 6 shows the mounting head 22 passing over the case 14 during this return. 1
B is a solder ball remaining on the lower surface of the mounting head 22 (hereinafter, referred to as “remaining ball”). Remaining ball 1B
Are those that failed to be mounted on the work 10 and remained on the lower surface of the mounting head 22.

The remaining ball 1B is detected by blocking the light path L from light. By driving the motor 24, the height of the mounting head 22 is set slightly lower on the return path than on the forward path, or by slightly raising the case 14 with a lifter (not shown) as shown in FIG. The light path L is shielded by the remaining ball 1B, and this can be detected.

When the remaining ball 1B is detected, the previous work 10 is a defective product having a shortage of the solder ball. Therefore, the work 10 is removed from the line, or a separate recovery means is provided on the electrode where the solder ball 1 does not exist. Refill the solder balls 1. In FIG. 6, the remaining balls 1B are forcibly dropped into the case 14 and collected by blowing air from the suction holes 25 of the mounting head 22. Next, the mounting head 22 returns to above the container 2, and the above-described operation is repeated.

(Embodiment 2) FIG. 8 is a side view of a conductive ball mounting apparatus according to Embodiment 2 of the present invention, and FIG. 9 is a light / dark image of the camera. Reference numeral 30 denotes a camera, and reference numeral 31 denotes a light source for irradiating illumination light upward. The mounting head 22 picking up the solder balls 1 in the container 2 moves above the camera 30, and
Observed by the camera 30.

FIG. 9 shows an image obtained by the camera 30. The solder ball 1 is a glossy metal sphere,
When light is emitted from below, only the light that has entered the center is strongly reflected downward and enters the camera 30, so that
Only the center of the solder ball 1 is observed brightly. The lower surface of the mounting head 22 is darkened such as black so that the camera 30 can observe the surface black. In FIG.
1 'is an image of a normal solder ball 1, and 1A' is an image of an extra ball. Therefore, the presence of the extra ball 1A can be easily detected by analyzing this image by a known image processing technique.

(Embodiment 3) FIG. 10 is a side view of a conductive ball mounting apparatus according to Embodiment 3 of the present invention, and FIG. 11 is a partial side view of the same. Reference numeral 32 denotes a laser unit, and the mounting head 22 is replaced with the light emitting element 17 and the light receiving element 18.
Is provided below the moving path.

By irradiating a laser spot light from the laser unit 32, scanning this laser spot light over the entire lower surface of the mounting head 22, and receiving the reflected light, the level distribution on the lower surface of the mounting head 22 can be detected.
Since the extra ball 1A protrudes below the normal solder ball 1, the presence or absence of the extra ball 1A can be easily confirmed by analyzing this level distribution by a well-known analysis technique.

In the present invention, various design changes are possible, and the detection of the remaining ball 1B shown in FIG. 6 may be performed by the camera 30 shown in FIG. 8 or the laser unit 32 shown in FIG. As the conductive balls, gold balls and the like can be used in addition to the solder balls.

[0028]

According to the present invention, an extra ball erroneously attached to the mounting head is detected, and only the conductive ball of the mounting head from which no extra ball is detected can be mounted on the work. Further, it is possible to easily detect the remaining ball remaining after the conductive ball is mounted on the work.

[Brief description of the drawings]

FIG. 1 is a side view of a conductive ball mounting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conductive ball transfer operation of the conductive ball mounting apparatus according to the first embodiment of the present invention.

FIG. 3 is an explanatory view of a conductive ball transfer operation of the conductive ball mounting apparatus according to the first embodiment of the present invention.

FIG. 4 is a perspective view of an extra ball detection unit of the conductive ball mounting device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of an extra ball detecting operation of the conductive ball mounting apparatus according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a detection operation of a residual ball of the conductive ball mounting device according to the first embodiment of the present invention;

FIG. 7 is a partially enlarged sectional view of a lower portion of a mounting head of the conductive ball mounting device according to the first embodiment of the present invention.

FIG. 8 is a side view of the conductive ball mounting apparatus according to the second embodiment of the present invention.

FIG. 9 is a light / dark image of a camera of the conductive ball mounting apparatus according to the second embodiment of the present invention.

FIG. 10 is a side view of a conductive ball mounting apparatus according to a third embodiment of the present invention.

FIG. 11 is a partial side view of a conductive ball mounting apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solder ball 1A Extra ball 1B Residual ball 2 Container 3 Base 4 Brush 10 Work 11 Clamper 14 Case 17 Light emitting element 18 Light receiving element 22 Mounting head 25 Suction hole 26 Moving table 30 Camera 31 Light source 32 Laser unit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 H01L 21/60 311 H01L 21/66

Claims (7)

(57) [Claims] 1. A method of mounting a conductive ball, wherein the conductive ball provided in a conductive ball supply section is adsorbed to a suction hole formed in a lower surface of a mounting head, picked up, and mounted on a work. After the head picks up the conductive balls, extra balls adhering to the lower surface of the mounting head are detected, and after the mounting head mounts the conductive balls on the work, the remaining balls adhering to the lower surface of the mounting head are detected. A method for mounting a conductive ball, characterized in that the conductive ball is detected. 2. The method according to claim 1, wherein the extra ball is detected by utilizing a height difference between the conductive ball and the extra ball normally adsorbed in the attraction hole and blocking light emitted from the light emitting element to the light receiving element. A method for mounting the conductive ball according to claim 1. 3. The method according to claim 1, wherein a recess is formed in the suction hole so that only one conductive ball can be sucked, and a height difference between the normally sucked conductive ball and the extra ball is ensured. Item 3. A method for mounting a conductive ball according to Item 2. 4. An extra ball, which is a glossy metal sphere, is obtained from an image of a lower surface of the mounting head where the conductive ball is observed brightly by irradiating light to the mounting head from a light source. The method for mounting a conductive ball according to claim 1, wherein the method further comprises: 5. The method for mounting a conductive ball according to claim 4, wherein the lower surface of the mounting head is dark, and the conductive ball, which is a glossy metal sphere, is observed brightly. 6. The method according to claim 6, wherein a level difference between the conductive ball and the extra ball normally sucked in the suction hole is used to scan a level distribution on a lower surface of the mounting head by a laser unit to detect the extra ball. The method for mounting a conductive ball according to claim 1, wherein: 7. The conductive ball supply section comprises a container for storing conductive balls, and when an extra ball is detected, the lower surface of the mounting head is placed in a layer of the conductive balls stored in the container. 7. The method for mounting a conductive ball according to claim 1, wherein the extra ball is forcibly dropped from the mounting head and collected in the container.