JP3397106B2 - Apparatus and method for transferring conductive balls - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive ball transfer device and method for transferring conductive balls onto a work.

[0002]

2. Description of the Related Art Flip chips and BGA (Ball G)
A method using conductive balls such as solder balls is known as a method of manufacturing an electronic component with bumps such as a grid array. Further, as a method of transferring the conductive balls to a work such as a chip or a substrate, a method using a suction head is widely practiced.

According to this method, conductive balls stored in a container or the like are vacuum-sucked and picked up in a large number of suction holes formed on the lower surface of the suction head, and the suction head is moved above the work to conduct these conductive balls. Since the conductive balls are transferred onto the electrodes of the work and a large number of conductive balls can be transferred onto the work all at once, there is an advantage that workability is good.

However, in the method of transferring the conductive balls to the work by using the suction head, a pickup error or a placement error as described below tends to occur when the conductive balls are vacuum-sucked. That is, when the conductive balls are vacuum-sucked by the suction head, the suction head is lowered into the supply portion of the conductive balls accumulated by stacking a large number of conductive balls. However, one conductive ball is not always vacuum-adsorbed. For example, when a plurality of conductive balls are vacuum-sucked to one suction hole and a large number of conductive balls are continuously attached to the lower surface of the suction head, or when the conductive balls remain attached to positions other than the suction hole. The suction head may rise.

Further, when the suction head is lowered onto the work and the vacuum suction is released to transfer the conductive balls to the work, all the conductive balls are not always completely removed from the suction holes. Instead, the conductive balls may remain attached to the lower surface of the suction head even after the suction head is raised.

Laser light or the like is used as a method for detecting the excessively attracted conductive balls and the conductive balls remaining on the lower surface of the suction head after the transfer onto the work. There is known a method of using the above optical sensor. This method uses the fact that the light emitted from the light emitting part of the optical sensor is received by the light receiving part, and when the conductive ball exists on the path of the light, the light is blocked and the amount of light received changes. Then, the presence or absence of the conductive ball is detected. As the type of light, laser light with good directivity is used, and the light is emitted as a circular spot light having a certain size from the light projecting unit. The range where the light receiving section receives the laser light is also a size corresponding to the diameter of this spot.

[0007]

However, as the diameter of the conductive balls becomes smaller, the size of the conductive balls to be detected becomes smaller than the size of the light receiving portion of the laser sensor which is the detecting means. However, there are problems as described below. 7A and 7B are partially enlarged views of the suction head of the conventional conductive ball transfer device, and FIG. 7A shows that the suction head 1 has the conductive balls 2 from the conductive ball supply portion. 7B shows the state after the pickup head is picked up, and FIG. 7B shows the state where the suction head 1 is lifted after the conductive ball 2 is transferred onto the work. Figure 7
In (a), the conductive balls 2 are additionally attached to the lower surface of the suction head 1. In such a state, in order to detect the presence or absence of the conductive balls 2 that are excessively attached or the conductive balls 2 that remain after the transfer, the suction head 1 is moved down with respect to the inspection unit including the laser sensor. . Figure 7
The dashed circle 3 shown in (a) and (b) is the spot diameter of the laser light received by the light receiving portion of the laser sensor, which is much larger than the diameter of the conductive ball 2 shown by the solid line.

As shown in FIG. 7A, even if one extra conductive ball 2 is attached to the lower surface of the suction head 1, the amount of light shielded by the extra conductive ball 2 is received. The ratio to the total amount of light received by the part is small,
Therefore, there is no clear difference in the amount of light received between the case where there is an extra conductive ball 2 and the case where it is normal, so the detection accuracy of the conductive ball 2 is low.

Further, in the example shown in FIG. 7B, there is a clear difference in the amount of light received when comparing (1) and (2).
It is possible to distinguish between the two cases, but when (2) and (3) are compared, the light receiving amounts are equal, and these two cases cannot be distinguished. Therefore, in the case of (3), despite the remaining conductive balls 2,
The conductive ball 2 cannot be detected because it is determined to be in the same state as (2).

The above-mentioned problems result from the fact that the spot diameter of the laser beam is larger than the diameter of the conductive ball to be detected. However, it is technically difficult to further reduce the spot diameter of the laser light of the optical sensor, and it is difficult to stably adjust the light amount for an optical sensor having a smaller spot diameter. Therefore, it is very difficult to address the above problems.

As described above, in the conventional conductive ball transfer device in which the optical sensor is used as the inspection unit for detecting the conductive balls, there is a pickup error in which the conductive balls are excessively attached to the lower surface of the suction head, There is a problem in that it is not possible to reliably detect a misplacement in which conductive balls remain on the lower surface of the suction head even after the transfer.

Therefore, the present invention is capable of reliably detecting a pick-up mistake or a place mistake of a conductive ball and correctly transferring the conductive ball onto the electrode of the work, and a conductive ball transfer device and transfer method. The purpose is to provide.

[0013]

According to a first aspect of the present invention, there is provided a conductive ball transfer device having a suction head having a plurality of suction holes for sucking the conductive balls formed on a lower surface thereof, and a ball supplying the conductive balls. A supply unit, a positioning unit for positioning the work, a vertical movement unit for moving the suction head up and down, a moving unit for moving the suction head between the ball supply unit and the positioning unit, and a light projecting unit and a light receiving unit. Light-shielding type optical sensor
Sensor and has a horizontal movement between the light emitter and the light receiver.
Vertical direction to adjust the range in which the presence or absence of the conductive ball adhered to the lower surface of the suction head for movement with the test unit for inspection, receiving light from the light projecting unit to the light receiving portion of the optical sensor
Equipped with a slit facing the width of the conductive ball
Equal to the diameter of .

According to a second aspect of the present invention , there is provided a conductive ball transfer device in which the width of the slit is irradiated from the light projecting portion.
It is smaller than the spot diameter of the light .

According to a third aspect of the present invention, there is provided a conductive ball transfer method for transferring conductive balls in a ball supply section onto a work by a suction head having a plurality of suction holes for sucking the conductive balls formed on a lower surface thereof. A method of transferring a conductive ball, the step of adjusting the height of the suction head relative to an inspection unit for inspecting the presence or absence of conductive balls attached to the lower surface of the suction head, and the inspection. Of the vertical direction that adjusts the range of light received from the light emitting unit to the light receiving unit
A slit that has a width equal to the diameter of the conductive ball.
Said suction head is relatively horizontally moved with respect to the light blocking type optical sensor having a preparative lower surface of the suction head after transfer of extra deposited conductive balls and or conductive balls on the lower surface of the suction head And the step of inspecting the presence or absence of conductive balls remaining and adhered to.

According to the present invention having the above-described structure, an inspection section is provided for inspecting the presence or absence of the conductive balls attached to the lower surface of the suction head by a light-shielding type optical sensor including a light projecting section and a light receiving section. By providing the light receiving part of the light receiving range adjusting means for adjusting the range of receiving the light from the light emitting part,
Even a small-diameter conductive ball can reliably detect a pickup error or a placement error.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a conductive ball transfer device according to an embodiment of the present invention, FIG. 2 is a sectional view of an inspection portion of the conductive ball transfer device, and FIG. 3 is a conductive ball transfer device. 5 is a perspective view of an optical sensor of the apparatus, FIGS. 4A and 4B are partially enlarged views of a suction head of the conductive ball transfer apparatus, and FIG.
FIG. 6 is a partial cross-sectional view of a ball supply portion of the conductive ball transfer device, and FIG. 6 is a partial front view of a positioning table of the conductive ball transfer device.

First, the overall structure of the conductive ball transfer device will be described with reference to FIG. In FIG. 1, a positioning table 5 is provided on the base 4. The positioning table 5 is composed of a Y table 6 and an X table 7.
A holder 8 is provided on the X table 7, and the holder 8 holds the work 9. Therefore, the work 9 is positioned at a predetermined position by driving the positioning table 5.

A ball supply unit 10 for the conductive balls 2 is arranged at the end of the base 4 opposite to the positioning table 5. The ball supply unit 10 includes a ball tank 11, and a plurality of layers of mesh plates 12 are horizontally spread inside the ball tank 11. The mesh plate 12 is provided with an innumerable number of openings of sizes that the conductive balls 2 cannot pass through. The conductive balls 2 are stored on the uppermost mesh plate 12. A nozzle 14 is arranged at the bottom of the ball tank 11, and the nozzle 14 is connected to a gas supply source (not shown). By supplying the gas to the nozzle 14, the gas blown upward from the nozzle 14 passes through the openings of the mesh plate 12 and is blown into the layer of the conductive balls 2 to fluidize the conductive balls 2.

Next, the suction head 31 for transferring the conductive balls 2 will be described. Reference numeral 20 shown in FIG. 1 is a moving means for moving the suction head 31 between the ball supply unit 10 and the positioning table 5. The suction head 31 is held by the block 30, and a plurality of suction holes 31 a are provided on the lower surface of the suction head 31. The block 30 is a vertical guide rail 2 provided on the front surface of the bracket 24.
It is attached to 5 so that it can move up and down. In block 30,
A nut 28 is integrally provided, and a vertical feed screw 26 is screwed into the nut 28. Therefore, when the Z-axis motor 27 is driven forward and backward and the feed screw 26 rotates forward and backward, the suction head 31 is guided by the guide rail 25 and moves up and down. Therefore, the Z-axis motor 27 and the feed screw 26 are vertical moving means for moving the suction head 31 up and down.

A nut (not shown) provided on the back surface of the bracket 24 is screwed into the horizontal feed screw 22.
Reference numeral 21 is a holding table for the feed screw 22. Therefore, when the X-axis motor 23 rotates forward and backward, the feed screw 22 rotates forward and backward, and the suction head 31 held by the bracket 24 horizontally moves between the positioning table 5 and the ball supply unit 10.

In FIG. 1, a ball supply unit 1 on a base 1
An inspection unit 40 is arranged on the side of 0. Inspection unit 4
In the case of 0, the presence or absence of the conductive ball 2 excessively adsorbed on the lower surface of the adsorption head 31 is inspected. The inspection unit 40 will be described below with reference to FIG. In FIG. 2, a sensor mounting bracket 42 is fixedly mounted on a base 41. The bracket 42 has a shape in which two tip portions are provided upright, and a light projecting portion 43a and a light receiving portion 43b of an optical sensor are attached to each tip portion. Light receiving section 43
On the front surface of b, there is a slit plate 4 as a light receiving range adjusting means.
4 is installed. The presence or absence of the conductive ball 2 on the optical axis a is measured by receiving the laser beam (shown by the optical axis a) emitted from the light projecting section 43a at the light receiving section 43b through the slit plate 44 and measuring the received light intensity. Can detect or.

Next, the slit plate 44 mounted on the surface of the light receiving portion 43b will be described with reference to FIG. As shown in FIG. 3, a slit plate 44, which is a light receiving range adjusting means, is attached so as to cover the light receiving element on the front surface of the light receiving section 43b. The slit plate 44 has a slit 44a in the vertical direction.
Is provided. The width of the slit 44a is smaller than the spot diameter of the laser light, and is set to be substantially equal to the diameter of the conductive ball 2.

The adjustment of the light receiving range by the slit plate 44 will be described below with reference to FIG. 4 (a), (b)
6 shows the positional relationship between the slit 44a, the conductive ball 2 and the spot diameter when the conductive ball 2 is on the optical axis a with the slit plate 44 attached. Conductive balls 2 shown in a) and (b)
This corresponds to the attachment mode of.

As shown in FIG. 4A, the slit plate 44
By mounting, the range of the laser light received by the light receiving portion 43b in the spot 3 of the laser light emitted from the light projecting portion 43a is adjusted by the slit 44a, and the width portion corresponding to the diameter of the conductive ball 2 is adjusted. Only the laser light is received by the light receiving portion 43b. Therefore, the difference in the amount of light received when the conductive ball 2 is present on the optical axis a and when it is not present is clear, and the conductive ball 2 can be reliably detected. Further, in the example shown in FIG. 4B, the light receiving range is limited by the slit 44a (1)
Since (3) and (3) receive light equally, and the difference in the amount of light received from (2) is clear, the presence or absence of the conductive ball 2 can be surely detected.

This conductive ball transfer device has the above-described structure, and its operation will be described below. First, in FIG. 1, the X-axis motor 23 is driven to move the suction head 31 above the ball supply unit 10. Therefore, the Z-axis motor 27 is driven to lower the suction head 31, and the lower surface of the suction head 31 is slightly submerged in the layer of the conductive balls 2.
At this time, gas is blown upward from the nozzle 14 of the ball tank 11 (see arrow a), and the conductive balls 2 are fluidized by the flow of this gas. Therefore, the conductive ball 2 is blown upward, and the suction head 31
It is vacuum-sucked to the suction holes 31a.

At this time, as shown in FIG. 5, the suction head 31 may ascend while the extra conductive balls 2 are attached to positions other than the suction holes 31a on the lower surface of the suction head 31. In this way, the presence or absence of the extra conductive balls 2 attached is detected by the inspection unit 40 so that the suction head 31 does not transfer to the work 9 while the extra conductive balls 2 are attached. To be done. First, the suction head 31 that has sucked the conductive balls 2 is moved above the inspection unit 40,
Next, the suction head 31 is lowered to adjust the relative height of the suction head 31 with respect to the inspection unit 40.
The height position of the conductive ball 2 on the lower surface of 1 is matched with the height of the optical axis a shown in FIG.

In this state, when the laser beam is emitted from the light projecting section 43a while moving the suction head 31 in the horizontal direction at a constant speed, the amount of the laser beam received by the light receiving section 43b depends on whether the conductive ball 2 is present or not. It changes with. That is,
Since a large number of conductive balls 2 are adsorbed in a matrix on the lower surface of the adsorption head 31, when the conductive balls 2 are located on the optical axis a, the laser light is blocked and the amount of light received decreases. It can be clearly distinguished from other cases.

Therefore, the amount of received light changes in a cycle corresponding to the arrangement pitch of the suction holes on the lower surface of the suction head 31. That is, outside the period corresponding to this array pitch,
If a portion with a small amount of received light is detected, it can be determined that extra conductive balls 2 are attached at positions other than the positions of the suction holes. In this way, it is possible to inspect the entire area of the lower surface of the suction head 31 for the presence or absence of extra conductive balls 2.

When an extra conductive ball 2 is detected on the lower surface of the suction head 31, the operation of the transfer device is stopped and the operator is informed accordingly. The operator
A treatment for removing the excessively attracted conductive balls 2 is performed, or a procedure such as returning the suction head 31 to the ball supply unit 10 to release vacuum suction and then performing a re-suction operation is performed.

The conductive heads 2 that have been excessively adhered are removed, and the conductive heads 2 are correctly vacuum-sucked and picked up one by one in all the suction holes 31a.
It moves horizontally above the positioning table 5. Next, the suction head 31 descends onto the work 9 held by the holder 8, and by releasing the vacuum suction, the conductive ball 2 is transferred onto the electrode 9a as shown in FIG. Transfer of 2 is completed.

Then, the suction head 31 is again inspected by the inspection unit 40.
Then, the presence or absence of the conductive balls 2 remaining on the lower surface after the transfer operation to the work 9 is inspected by the same method as the inspection of the extraly attached conductive balls 2. If the inspection detects that the conductive balls 2 remain, a place mistake is notified, and the work is repaired.

The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the conductive ball inspection unit 40 is fixed, and the suction head 3 is attached to the inspection unit 40.
1, the inspection unit 40 is movable, and the suction head 3 is stationary on the ball supply unit 10.
It is also possible to move the inspection unit 40 with respect to 1 and detect the presence or absence of the extra conductive ball 2.

[0034]

According to the present invention, it is possible to receive light portion is limited by adjusting the range adapted to the size of the conductive ball of the detection target range of the laser light received, the small diameter of the conductive ball Even in this case, the conductive ball attached to the lower surface of the suction head can be accurately detected, and a pickup error or a placement error can be reliably detected.

[Brief description of drawings]

FIG. 1 is a front view of a conductive ball transfer device according to an embodiment of the present invention.

FIG. 2 is a sectional view of an inspection portion of the conductive ball transfer device according to the embodiment of the present invention.

FIG. 3 is a perspective view of an optical sensor of a conductive ball transfer device according to an embodiment of the present invention.

FIG. 4A is a partially enlarged view of a suction head of a conductive ball transfer device according to an embodiment of the present invention. FIG. 4B is a suction head of a conductive ball transfer device according to an embodiment of the present invention. Partial enlarged view of

FIG. 5 is a partial cross-sectional view of a ball supply unit of the conductive ball transfer device according to the embodiment of the present invention.

FIG. 6 is a partial front view of a positioning table of the conductive ball transfer device according to the embodiment of the present invention.

7A is a partially enlarged view of a suction head of a conventional conductive ball transfer device, and FIG. 7B is a partially enlarged view of a suction head of a conventional conductive ball transfer device.

[Explanation of symbols]

2 conductive balls 4 bases 5 Positioning table 9 work 10-ball feeder 11 ball tank 23 X-axis motor 27 Z-axis motor 31 Suction head 31a adsorption hole 40 Inspection Department 43a Projector 43b Light receiving part 44 slit plate 44a slit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 H01L 23/12 H05K 3/34 505 B23K 3/06 B23P 21/00 305 B25J 15/06

Claims (4)

(57) [Claims] 1. A suction head having a plurality of suction holes for sucking conductive balls formed on a lower surface thereof, a ball supply unit for supplying the conductive balls, and a positioning unit for positioning a work.
A vertical movement means for moving the suction head up and down, a moving means for moving the suction head between a ball supply portion and a positioning portion, and a light-shielding type optical sensor including a light projecting portion and a light receiving portion.
The presence or absence of conductive balls attached to the lower surface of <br/> the suction head to move between the light receiving portion and the light projecting section in the horizontal direction has
Comprising a test unit for inspection, prior to the light receiving portion of the optical sensor
Vertical scan to adjust the range for receiving light from the serial light projecting portion
A slit, and the width of the slit is the diameter of the conductive ball.
A conductive ball transfer device characterized by equalization . 2. The width of the slit is radiated from the light projecting portion.
2. The conductive ball transfer device according to claim 1 , wherein the spot diameter is smaller than the spot diameter of the laser beam . 3. A conductive ball transfer method for transferring a conductive ball of a ball supply section onto a work by a suction head having a plurality of suction holes for sucking conductive balls formed on a lower surface thereof. The height adjustment process of adjusting the relative height of the suction head with respect to the inspection unit for inspecting the presence or absence of the conductive balls attached to the lower surface of the head, and the light receiving unit provided in the inspection unit from the light emitting unit. Adjust the light receiving range
A slit in the vertical direction that has a width equal to the diameter of the conductive ball
Of the suction head after the transfer of the conductive balls and / or the conductive balls that are excessively attached to the lower surface of the suction head by horizontally moving the suction head relative to the light-shielding type optical sensor having the slit. And a step of inspecting the presence or absence of conductive balls remaining and attached to the lower surface. 4. The width of the slit is radiated from the light projecting portion.
Characterized by being smaller than the spot diameter of the laser beam
The method for transferring conductive balls according to claim 3,