JP3371759B2 - Mounting method of conductive ball - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a conductive ball on a work pad. 2. Description of the Related Art As a method 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. In this method, a conductive ball provided in a conductive ball supply unit is vacuum-sucked to the lower surface of a suction head, picked up, and mounted on a work pad. It has the advantage that it can be mounted collectively. When a conductive ball is mounted, vacuum suction of the conductive ball is released and the conductive ball is dropped from the suction head. However, it takes time for the conductive ball to fall off the suction head when releasing the suction. Or a mounting error that remains in the suction hole without falling off may occur. As a means for solving such a problem, there is known a method of applying a positive air pressure to the suction head at the time of mounting the conductive ball to promote vacuum break in the suction head. Hereinafter, a conventional conductive ball mounting method will be described with reference to the drawings. FIG. 6 is an explanatory view of a conventional method for mounting a conductive ball. FIG. 6A shows a state in which a suction head 2 having vacuum-suctioned a conductive ball 1 is positioned above a work 4. At this time, the inside of the suction head 2 is at a negative pressure. Next, as shown in FIG. 6B, the suction head 2 is lowered, and the conductive ball 1 is landed on the pad 5 of the work 4 and mounted. Reference numeral 7 denotes a flux previously applied on the pad 5. At this time, a positive air pressure is applied to promote vacuum breakage inside the suction head 2, and then the pressure is reduced to the atmospheric pressure. This makes it easy for the conductive balls 1 to fall off from the suction holes 3. However, even with this method, the drop of the conductive ball 1 from the suction hole 3 is not always reliable, and a mounting error occurs with a certain probability. FIG. 6C shows a state in which the conductive ball 1 remains in one of the suction holes 3. Although the cause has not been sufficiently elucidated, it is presumed that burrs generated in the suction holes 3 by drilling when manufacturing the suction head 2 are related. The suction head 2 is made of a resin material, and the suction holes 3 are formed by directly drilling the resin with a drill. Therefore, as shown in FIG. 6, burrs 6 generated at the time of drilling may remain inside the suction holes 3. Since the burr 6 is a resin burr, it does not easily fall off, and since the burr 6 is located inside the hole, it is difficult to completely remove the burr 6 from the outside. The presence of the burrs 6 hinders the smooth flow of air inside the suction holes 3 and hinders the flow of air introduced for breaking vacuum when releasing vacuum suction. As a result, the conductive balls 1 are inserted into the suction holes 3 where the burrs 6 remain.
Is likely to occur, which is considered to be one cause of mounting errors. As described above, there has been a problem that a mounting error cannot be reliably prevented even if vacuum breakage is performed by air pressure when the conductive ball 1 is mounted. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for mounting a conductive ball which can reliably prevent mounting errors when mounting the conductive ball. According to the present invention, a vacuum suction is performed on the inside of a suction head so that conductive balls provided in a supply section are vacuum-sucked in suction holes formed in a lower surface of the suction head. And picking up the workpiece, and causing the suction head to perform a descending / elevating operation with respect to the work positioned at the positioning section, thereby mounting the conductive ball on a pad of the work. When the conductive ball is mounted on the work pad, a positive pressure is applied to the inside of the suction head to break a vacuum state, and the pressure inside the suction head is pulsated to drop the conductive ball. did. According to the present invention, when a suction head mounts a conductive ball on a pad of a work, the vacuum state inside the suction head is actively broken, and the pressure inside the suction head is reduced. By pulsating, the conductive ball that has been vacuum-sucked in the suction hole is quickly dropped from the suction hole, and can be reliably mounted on the pad. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a conductive ball mounting apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a suction head of the conductive ball mounting apparatus, and FIG. FIG. 4 is an explanatory view of the mounting operation, FIG. 4 is a time chart of the operation of the suction head of the conductive ball mounting device, and FIG. 5 is a partial sectional view of the suction head of the conductive ball mounting device. First, the overall structure of the conductive ball mounting device will be described with reference to FIG. Reference numeral 10 denotes a container serving as a supply portion of a conductive ball, in which the conductive ball 1 is stored. 9 is a base. Reference numeral 11 denotes a work on which a large number of pads 12 are formed.
The work 11 is positioned on the positioning section 13.
The positioning unit 13 is a movable table, and
The position can be adjusted by horizontally moving in the direction or the Y direction. A moving table 14 is provided above the container 10 and the positioning unit 13. The moving table 14 holds a case 15, and the case 15 holds a suction head 21. When the moving table 14 is driven, the case 15 and the suction head 21 are moved to the moving table 1.
4 and moves between the container 10 and the work 11. In FIG. 2, a motor 1 is mounted on a case 15.
6 are provided. A vertical feed screw 17 is provided inside the case 15. A nut 18 is attached to the feed screw 17, and the suction head 21 is
8. Therefore, when the motor 16 is driven and the feed screw 17 rotates, the nut 18
, And the suction head 21 also moves up and down. That is, the motor 16, the feed screw 17, and the nut 18 serve as a means for vertically moving the suction head 21. 19 is case 15
A vertical guide rail 20 provided on the front face of the suction head 21 is a slider provided on the back face of the suction head 21 and fitted to the guide rail 19.
0 guides the vertical movement of the suction head 21. In FIG. 2, there is a space 22 inside the suction head 21, and a number of suction holes 23 are formed on the lower surface thereof. Reference numeral 24 denotes a suction unit, which is connected to the space 22 via a first valve 25 and pipes 26 and 27. 2
Reference numeral 8 denotes a high-pressure air supply unit, which includes a second valve 29 and a pipe 2.
It is connected to the space 22 via 6, 27. Reference numeral 30 denotes a third valve, which is connected to the space 22 via a pipe 27. A fourth valve 31 is connected to the space 22 via a pipe 32. A control unit 33 controls the suction unit 24, the high-pressure air supply unit 28, the first valve 25, the second valve 29, the third valve 30, the fourth valve 31, and the motor control unit 34. The motor control unit 34 controls driving of the motor 16. A storage unit 35 stores data necessary for operating the apparatus. Reference numeral 36 denotes an input unit such as a keyboard and a mouse for inputting necessary data. This conductive ball mounting apparatus has the above-described configuration, and the entire operation will be described next. In FIG. 1, the suction head 21 moves above the container 10, and performs a lowering / upward operation to vacuum-suck the conductive ball 1 to the suction hole 23 to pick it up. Next, the suction head 21 moves above the work 11, where the suction head 21 performs the lowering / upward operation again to mount the conductive ball 1 on the pad 12 of the work 11. Next, the operation of the suction head 21 will be described in detail with reference to FIGS. In FIG. 4, (a)
Indicates the height of the suction head 21. (B),
(C) and (d) show the first valve 25 and the second valve 2 respectively.
9, the opening and closing operations of the third valve 30 and the fourth valve 31 are shown. (E) shows a change in the internal pressure of the space 22 of the suction head 21. In FIG. 4 (a), when the suction head 21 performs a suction operation for picking up the conductive balls 1 stored in the container 10, at a timing t1 as shown in FIG. 4 (b). The first valve 25 opens and the suction unit 24 starts vacuum suction of the space 22 at the same time as the start of the downward movement of 21. Thereby, as shown in FIG. 4E, the internal pressure of the space 22 decreases from the atmospheric pressure to the negative pressure. At timing t2, the suction head 21 stops descending, and the conductive ball 1 is vacuum-sucked into the suction hole 23. Next, at timing t3, the suction head 21 starts to rise,
The movement operation to the work 11 is started. During the above, the second valve 29, the third valve 30, and the fourth valve 31 are closed. Next, the suction head 21 moves from the moving operation to the mounting operation. That is, the descent starts at the timing t4 and ends at the timing t5. FIG. 3 (a)
The state at timing t4 is shown. In this state, the suction head 21 is located directly above the work 11. At this time, the flux 37 has already been applied to the pad 12 by a flux applying means (not shown). FIG. 3B shows the state at the timing t5. In this state, the conductive ball 1 lands on the pad 12. Next, by closing the first valve 25 at timing 6, the vacuum suction by the suction unit 24 is stopped, and the second valve 29 is opened to send air from the high-pressure air supply unit 28 to the space 22. Can be As a result, the interior of the space 22 is broken by vacuum, and the internal pressure rises rapidly as shown in FIG. 4 (e) and instantaneously switches from negative pressure to positive pressure. Next, at timing t7, the third valve 30 and / or the fourth valve 31
open. Then, the space 22 communicates with the outside, and the outside air is instantaneously introduced into the space 22, and the internal pressure of the space 22 rapidly decreases from the positive pressure to the atmospheric pressure (timing t8). At the same timing 8, the third valve 3
The 0 and / or fourth valve 31 is closed, and the second valve 29 is opened again to send air from the high pressure air supply unit 28 to the space 22. Thereby, the internal pressure of the space 22 rapidly rises again. Then, by opening the third valve 30 and / or the fourth valve 31 at the timing 9, the space 22 communicates with the outside, the outside air is instantaneously introduced into the space 22, and the internal pressure of the space 22 is reduced. Again, the pressure suddenly drops from the positive pressure to the atmospheric pressure (timing 10). During the period from the timing t6 to the timing t10, the suction head 21 is kept lowered in order to prevent the conductive ball 1 from being blown off by the air blown out of the space 22 which has become a positive pressure. At 23, the position of the conductive ball 1 is regulated so as not to move. As described above, the pressure in the space 22 inside the suction head 21 is changed from the timing t6 to the timing t10.
During this period, rapid pulsation of negative pressure → positive pressure → atmospheric pressure → positive pressure → atmospheric pressure is repeated, and the suction hole 23 actively releases the vacuum suction state of the conductive ball 1. At timing t10, the third valve 30 and / or the fourth valve 31 are closed, and the suction head 21 starts to move up (see FIG. 3C), and a series of mounting operations ends. As described above, according to the present method, positive pressure is applied from the high-pressure air supply unit 28 to the space 22 in the suction head 21 to positively break the vacuum in the space 22 and pulsate the pressure in the suction head 21. By doing so, the dropping of the conductive ball 1 from the suction hole 23 is promoted, and the conductive ball 1 can be mounted on the pad 12 of the work 11 in a short time. Note that the timings t1 to t1
t10 is registered in the storage unit 35 in advance as program data. Although the function and effect of pulsating the pressure inside the suction head 21 have not been completely elucidated, the following effects are presumed. The lower surface of the suction head 21 is made of a resin material, and when forming the suction hole 23 on this lower surface, hole processing by a drill is performed. At the time of drilling, as shown in FIG. 5A, burrs 6 are easily generated inside the suction holes 23. Since the burrs 6 are resin burrs having high elasticity, it is difficult to remove them after processing. is there. For this reason, the burrs 6 remain inside the suction holes 23 at a certain rate even during actual use, and the smooth flow of air in the suction holes 23 (see arrow a) as shown in FIG. Is considered to be inhibiting. Therefore, by pulsating the pressure inside the suction head 21 to alternately change the flow direction of the air inside the suction hole 23 in the forward and reverse directions, the function of vibrating the burr 6 inside the suction hole 23 works. Then, as shown in FIG. 5C, the direction of the burr 6 is changed to form a gap, and air pressure acts on the conductive ball 1 from the gap (see arrow b), and the space from the suction hole 23 of the conductive ball 1 is removed. It is presumed that the dropout is promoted. In an actual application, it has been confirmed that the pulsation of the pressure in the suction head 21 significantly reduces mounting errors. In the present embodiment, an example is shown in which the opening and closing of each valve for applying air pressure to the suction head 21 is performed twice. However, the present invention is not limited to this, and the number of times of applying air pressure is more than this. There may be. According to the present invention, when the suction head mounts the conductive ball on the work pad, the vacuum state inside the suction ball is actively broken, and the pressure inside the suction head is pulsated. As a result, the burrs remaining inside the suction holes and obstructing the smooth flow of air are vibrated to change the direction of the burrs, thereby smoothing the air flow, and as a result, the air pressure is applied to the conductive balls. By acting, the conductive balls that have been vacuum-sucked in the suction holes are promoted to fall out of the suction holes, and the conductive balls can be reliably mounted on the pads of the work.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of an apparatus for mounting a conductive ball according to an embodiment of the present invention; FIG. 2 is a view illustrating a suction head of the apparatus for mounting a conductive ball according to an embodiment of the present invention; FIG. 3 is a diagram illustrating a mounting operation of a conductive ball mounting device according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an operation of a suction head of the conductive ball mounting device according to an embodiment of the present invention. Time chart [FIG. 5] Partial sectional view of a suction head of a conductive ball mounting apparatus according to an embodiment of the present invention [FIG. 6] Description of a conventional conductive ball mounting method [Description of symbols] 1 Conductivity Ball 5 container 11 work 12 pad 13 positioning unit 16 motor 17 feed screw 18 nut 21 suction head 22 space 23 suction hole 24 suction unit 25 first valve 28 high-pressure air supply unit 29 second valve 30 third valve 31 4 valve 33 control unit 35 Part

Continuation of the front page (56) References JP-A-7-153766 (JP, A) JP-A-8-153959 (JP, A) JP-A-5-129374 (JP, A) JP-A-7-251263 (JP) , A) JP-A-8-107121 (JP, A) JP-A-11-216696 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/60 B23Q 3/08 F23P 21/00

Claims (1)

(57) [Claim 1] The inside of the suction head is vacuum-suctioned, so that the conductive balls provided in the supply section are vacuum-sucked into the suction holes formed in the lower surface of the suction head. A method of mounting a conductive ball on a pad of a work by causing a suction head to perform a lowering / elevating operation on a work positioned at a positioning portion after the pickup, the conductive ball being provided. When mounting on the work pad, applying a positive pressure to the inside of the suction head to break the vacuum state, and pulsating the pressure inside the suction head to drop the conductive ball from the suction hole. A method for mounting a conductive ball, comprising: