JP3449178B2 - Transfer method of conductive ball - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transferring a conductive ball to a workpiece. 2. Description of the Related Art A flip chip or a BGA (Ball G
2. Description of the Related Art As a method for manufacturing an electronic component with a bump such as a lid array, a method using a conductive ball such as a solder ball is widely used. As a method for transferring the conductive balls to a work such as a chip or a substrate, a method using a suction tool is known. In this method, conductive balls stored in a container or the like are vacuum-sucked into suction holes formed in a large number on the lower surface of a suction tool, picked up, and the suction tool is moved above a workpiece to move these conductive balls. Since the conductive balls are transferred onto the electrodes of the work, a large number of conductive balls can be collectively transferred to the work, and thus there is an advantage that workability is good. [0004] However, in the method of transferring conductive balls to a work by using a suction tool, a pick-up mistake as described below occurs when the conductive balls are vacuum-sucked. Likely to happen. When the conductive tool is vacuum-sucked by the suction tool, the suction tool is lowered into the supply portion of the conductive ball where a large number of conductive balls are stacked and stored. Therefore, one conductive ball is not always reliably vacuum-adsorbed. For example, it takes time for the conductive ball to be vacuum-sucked to the suction hole, and the suction tool may rise with some of the suction holes without vacuuming the conductive ball. Conversely, a plurality of conductive balls may be vacuum-sucked into one suction hole, and the conductive balls may adhere in succession. As described above, in the method using the suction tool, a pickup error is likely to occur, and there is a problem that the conductive balls may not be correctly transferred one by one on each electrode of the work. SUMMARY OF THE INVENTION The present invention provides a method for transferring conductive balls, which can eliminate pick-up of conductive balls and can surely transfer conductive balls one by one onto electrodes of a work. Aim. According to a first aspect of the present invention, there is provided a method for transferring a conductive ball, comprising: causing a suction tool to perform a vertical movement with respect to a supply portion of the conductive ball; Picking up the conductive balls by vacuum suction into the plurality of suction holes, and then moving the suction tool relatively above the workpiece, causing the suction tool to move up and down again and release the vacuum suction. A method of transferring a conductive ball vacuum-sucked to the suction hole to a workpiece, wherein the suction tool moves up and down to vacuum-suction the conductive ball of the supply unit. The vacuum degree in the suction tool is measured by the vacuum measurement unit when picking up and if the vacuum degree does not reach the predetermined degree within the predetermined time , a large number of conductive balls around the suction hole
Is determined to be a large number of suctions, and the vacuum suction is released.
The plurality of conductive balls are dropped, and the conductive balls are picked up again. According to the method for transferring conductive balls according to the first aspect of the present invention, the suction tool moves up and down to vacuum-pick up and pick up the conductive balls in the supply section. At this time, measure the degree of vacuum in the suction tool, if the vacuum degree does not reach the predetermined degree within a predetermined time, release the vacuum suction state and drop the conductive ball, and then vacuum suction the conductive ball again By performing the pickup again, one conductive ball can be surely sucked into each suction hole and transferred to the work. (Embodiment 1) Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of an apparatus for transferring conductive balls according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view of a transfer head of the apparatus for transferring conductive balls, FIG. 3, FIG. FIG. 6 is a partial sectional view 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 supply unit 10 for conductive balls is provided on a base 11. The supply unit 10 includes a container 14, and a vibrator 16 serving as a vibration applying unit is provided on a lower surface of the container 14. Vibrator 16
Are supported on the bottom surface of the box 15,
Is mounted on the base 12. Inside the container 14, a large number of solder balls 1 as conductive balls are stored. By driving the vibrator 16, vibration is transmitted to the stored solder balls 1 via the container 14, and the solder balls 1 vibrate. On the side of the supply section 10 on the base 11, a positioning section 20 for a substrate 26 as a work is provided. The positioning section 20 is configured by stacking an X table section 21 and a Y table section 23 and further mounting a clamper 25 for clamping a substrate 26 thereon. When the motor 22 of the X table unit 21 is driven, the substrate 26 moves in the X direction, and when the motor 24 of the Y table unit 23 is driven, the substrate 26 moves in the Y direction. Thus, the substrate 26
Is horizontally moved to position the substrate 26. A transfer head 30 is provided above the supply unit 10. A suction tool 32 is mounted on the lower end of the transfer head 30. The transfer head 30 is a Z table 5
It is held at 0. A nut (not shown) provided on the back surface of the Z table 50 is screwed into the horizontal feed screw 28. Reference numeral 29 denotes a holding table for the feed screw 28. Therefore, when the X-axis motor 27 rotates forward and backward, the feed screw 2
8 rotates forward and backward, and the table 50 moves horizontally. When the transfer head 30 moves up and down on the supply unit 10,
The suction tool 32 vacuum-adsorbs and picks up the solder ball 1 on its lower surface. After that, the table 50 moves horizontally on the positioning section 20, and the transfer head 30 moves up and down again.
Is transferred onto the substrate 26. Next, the structure of the transfer head 30 will be described with reference to FIG. 31 is a box as a main body. Box 31 is bottomless and has a block 34 inside.
Is stored. A box-shaped suction tool 32 is connected to a lower portion of the block 34. The suction tool 32 is connected to a suction unit 36 via a tube 33, and when the suction unit 36 is operated, the solder balls 1 are vacuum-sucked into suction holes 35 formed on a plurality of lower surfaces thereof. Further, a vibrator 43 as a vibration applying means is mounted on the suction tool 32. When the vibrator 43 is driven, the lower surface of the suction tool 32 vibrates, and vibrates relative to the solder ball 1 when the solder ball 1 is vacuum-sucked. In FIG. 2, the side end of the block 34 is pressed against the bottom plate 31a of the box 31 to ensure the parallelism of the lower surface of the suction tool 32 to the horizontal plane. That is, the bottom plate 31a defines a lower limit of the suction tool 32 and serves as a stopper for setting the lower surface of the suction tool 32 to a horizontal plane. Further, in the present embodiment, since the both sides of the block 34 are in contact with the stoppers, the parallelism of the lower surface of the suction tool 32 can be maintained with good reproducibility. A cylinder 38 is provided on the upper surface of the box 31, and a block 34 is connected to a lower end of a rod 39 of the cylinder 38. Reference numeral 40 denotes a spring material, which connects the ceiling surface of the box 31 and the upper surface of the block 34. The spring material 40 resiliently pushes the block 31 upward by its spring force, thereby reducing its own weight on the suction tool 32 side.
In the present embodiment, the spring force of the spring material 40 is
1 and the suction tool 32. Sliders 41 provided on both side surfaces of the block 31 are slidably fitted on vertical rails 42 provided on the inner surface of the box 31. Next, the means for vertically moving the box 31 will be described. Reference numeral 50 denotes a vertically long drive case provided on a side portion of the box 31 and a vertical ball screw 51 therein.
Is stored. A nut 52 is screwed into the ball screw 51, and the nut 52 is connected to the box 31 via a rod 53. A vertical rail 54 is provided on a side surface of the drive case 50, and a slider 55 provided on a side surface of the box 31 is slidably fitted to the rail 54. The motor 56 is driven to drive the ball screw 5
When 1 rotates, the nut 52 moves up and down along the ball screw 51. Thereby, the box 31 and the suction tool 3
2 performs up and down operations. Reference numeral 60 denotes a control unit, which is a suction unit 3
6. Control the motor drive circuit 61, the pressing force control unit 62, the vibrator drive circuit 64, and the like. 63 is a pressure source of the cylinder 38. The motor drive circuit 61 controls the motor 56. The pressing force controller 62 controls the pressing force of the cylinder 38. The vacuum degree measuring unit 65 measures the degree of vacuum in the suction tool 32, and sends a signal of the measured degree of vacuum to the control unit 60. This device for transferring conductive balls has the above-described configuration, and the operation will be described with reference to the drawings.
In FIG. 1, the transfer head 30 moves above the supply unit 10. Next, when the motor 56 is driven, the transfer head 30 is lowered and raised, and the suction tool 32 is
The conductive ball 1 is vacuum-sucked into the suction hole 35 on the lower surface and picked up. Hereinafter, the suction operation at this time will be described in detail with reference to FIGS. First, in FIG. 3, the suction tool 32 is moved up and down into the container 14 (see arrow a),
When 6 is driven, the inside of the suction tool 32 is suctioned by vacuum.
As a result, the inside of the suction tool 32 becomes negative pressure,
By sucking air from the container (see arrow b)
Then, the solder ball 1 in 4 is vacuum-adsorbed to the suction hole 35. However, at this time, one solder ball 1 is not necessarily vacuum-sucked into one suction hole 35, and a large number of solder balls 1 are spread over the lower surface of the suction tool 32 as shown in FIG. May adhere over a range. This is because a plurality of solder balls 1
Is sucked, and the suction hole 35 is not completely closed. As a result, a leak occurs in the suction hole 35, and the surrounding air is continuously sucked from the suction hole 35 (see arrow c). A large number of solder balls 1 are held by the suction tool 32 by force.
This is because it is sucked by the lower surface of the. Such suction of a large number of solder balls is less likely to occur in the case of a solder ball having a relatively large diameter because the weight of the solder ball is large. However, the self-weight of the solder ball decreases in proportion to the cube of the diameter, so that the small-diameter solder ball has an extremely small self-weight. As a result, in the case of a small-diameter solder ball, it is easy to be sucked even by a slight suction force generated around the suction hole 35, and the above-described large number of pieces are easily sucked. As described above, the multiple suction is performed by the suction holes 35.
Due to air leaks. In other words, if air leakage is detected, it is possible to determine the presence / absence of multiple suction. Therefore, the present invention focuses on this point and provides a vacuum degree measuring unit 65 for measuring the degree of vacuum in the suction tool 32. When the transfer head 30 moves up and down to pick up the solder ball 1 of the supply unit 10 by vacuum suction, the degree of vacuum in the suction tool 32 is measured to detect the presence or absence of multiple suction. I made it. If the predetermined degree of vacuum is not reached,
It is determined that a pickup error has occurred due to suction of a large number of pieces, and as shown in FIG. 4, air is introduced into the suction tool 32 through the pipe 33 (see arrow d), and the vacuum suction state is released. Then, the large number of solder balls 1 attached to the lower surface of the suction tool 32 drop off from the suction tool 32 and fall into the container 14 (see arrow e). Thereafter, as shown in FIG.
Is lowered (see arrow f), and the suction unit 36 is driven again so as to perform pickup by vacuum suction again (see arrow g). In this case as well, the degree of vacuum in the suction tool 32 is measured, and if the predetermined degree of vacuum is not reached within a predetermined time, the vacuum suction state is released again, and then pickup is further performed by vacuum suction. FIG. 6 shows a state where the solder balls 1 are normally sucked one by one into the suction holes 35 of the suction tool 32 after the vacuum suction operation is repeated in this manner. The number of repetitions of the vacuum suction is set in advance. If the predetermined degree of vacuum is not reached even after repeating the set number of suction operations, a notification means such as an alarm is driven as a vacuum suction abnormality to notify the operator of the fact. Then, the transfer device stops. As shown in FIG. 6, the transfer head 30 that has normally picked up the solder ball 1 moves above the substrate 26, and causes the suction tool 32 to perform the up and down operation again and release the vacuum suction state. Thereby, the solder ball 1 vacuum-adsorbed to the suction hole 35 is transferred onto the substrate 26. As described above, by measuring the degree of vacuum in the suction tool 32 during the vacuum suction of the solder ball 1,
It is possible to simply and reliably detect whether or not the vacuum suction operation has been normally performed.
Transfer mistakes in which a large number of solder balls 1 are transferred by mistake on the surface 6 can be prevented. (Embodiment 2) FIG. 7 is a partial sectional view of an apparatus for transferring conductive balls according to Embodiment 2 of the present invention.
(A), (b), (c) is a partial sectional view of the suction tool of the conductive ball transfer device. FIG. 7 shows the suction tool 3
2 shows a state where the suction unit 36 is driven to perform the suction operation by landing the layer 2 on the layered solder ball 1 in the container 14 (see arrow h). As a result, as shown in FIG. 8A, air is sucked from each suction hole 35 of the suction tool 32 (see arrow i), and the solder ball 1 abutting on the lower surface of the suction tool 32 is vacuum-sucked. At this time, as shown in FIG. 8A, a plurality of solder balls 1
May adhere to each other to prevent the solder balls 1 from entering the suction port 5, and none of the solder balls 1 may be normally sucked into the suction hole 35. Then, as shown in FIG. 8B, the transfer head 30 is slightly lowered (see arrow j), and the lower surface of the suction tool 32 is lightly pressed against the layered solder balls 1 in the container 14. Then, one or both of the vibrators 16 and 43 are driven to vibrate the suction tool 32 relative to the layered solder ball 1. Then, the solder ball 1 is gradually moved in the horizontal or vertical direction by the vibration, and
The solder ball 1, which is closest to the position 5 and is easily sucked, is guided into the suction hole 35 and moves gradually (see arrow k). Thereafter, as shown in FIG. 8C, the solder ball 1 is completely fitted into the suction hole 35 and sucked. At this time, the suction tool 32 is
The pressing force is set by the pressure control unit 62 so that the pressing force applied to the solder ball 32 transmits vibration from the suction tool 32 to the solder ball 1 and does not hinder the small movement of the solder ball 1. I do. Also, the size of the solder ball 1 and the size of the container 14 are set so that the vibration is transmitted efficiently.
The vibration frequency and amplitude of the vibrators 16 and 43 are set by the vibration drive circuit 64 in accordance with the amount of the solder balls 1 stored therein. By causing the suction tool 1 to vibrate relative to the solder ball 1 while pressing the suction tool 32 against the solder ball 1 in this manner, the solder ball 1 is guided to each suction hole 35 of the suction tool 32. Thus, the solder ball 1 can be quickly and stably vacuum-adsorbed. Thereafter, the suction tool 32 having vacuum-sucked the solder ball 1 into each of the suction holes 35 rises, and the transfer head 30 moves horizontally above the positioning section 20. Then, the suction tool 32 moves up and down again to transfer the solder ball 1 onto the substrate 26. According to the present invention, the degree of vacuum in the suction head is measured when the conductive ball is picked up by vacuum suction, and when the predetermined degree of vacuum is not reached within a predetermined time.
A large number of conductive balls are sucked around suction holes
Judgment is made as individual suction , the vacuum suction state is released, the conductive balls are dropped, and then the conductive balls are vacuum-adsorbed again to pick up again. In this case, the state in which the conductive balls are unstablely adsorbed can be eliminated, and the conductive balls can be surely adsorbed one by one in each of the adsorbing holes, thereby preventing a pickup error or a transfer error. [0034]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a conductive ball transfer device according to a first embodiment of the present invention. FIG. 2 is a conductive ball transfer device according to a first embodiment of the present invention. FIG. 3 is a partial cross-sectional view of the conductive ball transfer device according to the first embodiment of the present invention. FIG. 4 is a partial cross-sectional view of the conductive ball transfer device according to the first embodiment of the present invention. FIG. 5 is a partial cross-sectional view of the conductive ball transfer device according to the first embodiment of the present invention. FIG. 6 is a partial cross-sectional view of the conductive ball transfer device of the first embodiment of the present invention. FIG. 8 (a) is a partial cross-sectional view of a suction tool of the conductive ball transfer device according to the second embodiment of the present invention (FIG. 8A). b) Partial sectional view of a suction tool of the conductive ball transfer device according to the second embodiment of the present invention. (c) Conductive board according to the second embodiment of the present invention. [Description of References] 1 Solder ball 10 Supply unit 14 Container 16 Vibrator 20 Positioning unit 26 Substrate 32 Suction tool 35 Suction hole 43 Vibrator

Claims (1)

(57) Claims: 1. A suction tool is moved up and down with respect to a supply portion of a conductive ball, and a plurality of conductive holes are formed in a plurality of suction holes formed on a lower surface of the suction tool. Is picked up by vacuum suction, and then the suction tool is relatively moved above the work, and the suction tool is moved up and down again, and the vacuum suction is released. A method of transferring a conductive ball in which a conductive ball is transferred to a workpiece, wherein the suction tool moves up and down to vacuum-suction and pick up the conductive ball in the supply section. The degree of vacuum is measured by the vacuum measuring unit, and if the predetermined degree of vacuum is not reached within the predetermined time , a large number of conductive balls
Determined number is sucked pieces aspirated, prior to releasing the vacuum suction
A method of transferring a conductive ball, comprising dropping a large number of the conductive balls, and picking up the conductive ball again.