JP3211801B2 - Extra ball detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for detecting an extra ball when a conductive ball for forming a bump is formed 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 for detecting an extra ball which can prevent the extra ball from being erroneously mounted on a work.

[0005]

SUMMARY OF THE INVENTION According to the present invention, after a conductive ball provided in a conductive ball supply section is sucked and picked up by a concave portion of a suction hole formed in a lower surface of a mounting head, light is emitted from a light source. A camera obtains an image of the lower surface of the mounting head where the conductive balls are observed brightly by irradiating with a camera. From this image , an extra image is attached to the lower surface without being stored in the concave portion.
A method for detecting an extra ball, which is a glossy metal sphere worn , wherein the lower surface of the mounting head is darkened.
To brighten the conductive balls, which are glossy metal spheres
Observed .

[0006]

According to the present invention, extra balls erroneously attached to the mounting head are detected by irradiating light from a light source and observing the lower surface of the mounting head with a camera, and no extra balls are detected. Only the conductive balls of the mounting head can be mounted on the work.

[0008]

FIG. 1 is a side view of a conductive ball mounting apparatus according to an embodiment of the present invention, FIG. 2 is a light / dark image of the camera, and FIG. 3 is a partially enlarged cross section of a lower portion of the mounting head. FIG.

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.

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. 3, the suction hole 25 is formed with a tapered recess 25a capable of sucking only one solder ball 1, and when the solder ball 1 is normally sucked, is housed in the recess 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 FIG. 1, reference numeral 30 denotes a camera, and 31 denotes a light source for irradiating the illumination light upward. The light source 31 is provided below the moving path of the mounting head 22.
Observe the underside of 2. The mounting head 22 picking up the solder balls 1 in the container 2 moves above the camera 30 and is observed by the camera 30.

FIG. 2 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.

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 the container 2, the camera 30, the light source 31, and the work 1
Move horizontally between 0.

This conductive ball mounting apparatus is configured 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. 3, 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. At this time, the mounting head 22 passes above the brush 4, and the upper end of the brush 4 comes into sliding contact with the solder ball 1 held on the lower surface of the mounting head 22. Of the solder balls shown in FIG. 3, the normal solder ball 1 that has been correctly vacuum-sucked directly to the suction hole 25 is strongly vacuum-sucked and held, so that it does not drop even when the brush 4 slides, but the extra ball 1A Is held by a weak force due to static electricity or the like.

As in this embodiment, the mounting head 2
The brush 4 is provided on the moving path 2 and the solder ball 1
If the solder ball 1 is brought into sliding contact with the
During the transfer, the extra ball 1A can be easily dropped and removed. Further, by providing the brush 4 in the container 2, the extra ball 1 </ b> A dropped by the brush 4 can be collected in the container 2 as it is.

Next, the mounting head 22 moves above the camera 30, and the lower surface of the mounting head 22 is observed by the camera 30. As described above, the extra ball 1A is
The sliding contact drop is not always successful, and the extra ball 1A may still remain as shown in FIG. Then, the lower surface of the mounting head 22 was observed with the camera 30, and FIG.
The extra ball 1A is detected by obtaining the image shown in FIG.

As described above, when the extra ball 1A is detected, various methods are available, and some of them will be described below. First, the first method is to operate the pneumatic unit (not shown) in the opposite direction, thereby causing the suction holes 25 to operate.
By blowing air from the device or releasing the vacuum suction state, all the solder balls 1 and the extra balls 1A held by the mounting head 22 are dropped and collected. Then, the mounting head 22 is returned above the container 2,
Redo the pickup operation.

In the second method, the mounting head 22 is returned above the container 2 and is moved again above the brush 4, so that the extra ball 1A is slid and dropped by the brush 4 again.

A third method is to return the mounting head 22 to a position above the container 2 and lower the mounting head 22 so that the lower surface of the mounting head 22 enters the layer of the solder balls 1 stored in the container 2 in large quantities. 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 workpiece 10 as described above, the mounting head 22
Return to above.

[0024]

According to the present invention, extra balls that have erroneously adhered to the mounting head can be detected, and only normal conductive balls can be mounted on the work.

[Brief description of the drawings]

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

FIG. 2 is a light and dark image of a camera of the conductive ball mounting apparatus according to the embodiment of the present invention;

FIG. 3 is a partially enlarged sectional view of a lower portion of a mounting head of the conductive ball mounting apparatus according to one embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 solder ball 1A extra ball 2 container 3 base 4 brush 10 work 11 clamper 22 mounting head 25 suction hole 26 moving table 30 camera 31 light source

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 H01L 21/66

Claims (1)

(57) [Claims] 1. A conductive ball provided in a conductive ball supply unit is sucked and picked up by a concave portion of a suction hole formed on a lower surface of a mounting head, and then irradiated with light from a light source to form the conductive ball. An image of the lower surface of the mounting head, which is observed brightly, is obtained with a camera, and is stored in the recess from the image.
A method for detecting an extra ball, which is a glossy metal sphere extraly attached to the lower surface without being detected ,
The lower surface of the mounting head is a dark colored and glossy metal sphere
A method for detecting an extra ball, wherein a certain conductive ball is observed brightly .