JP2001018361A - Transfer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer head which does not generate a swelling phenomenon in the center part of a screen even when a transfer head is to be pressed to a flux supply part, and also produces no difference in the coating build-up of a flux between the center part and the periphery of the screen and further, is capable of making the coating build-up of the flux uniform. SOLUTION: A means as described below is adopted on the transfer head 13, across the lower face frame of which a screen with transfer protrusions 40 formed on the lower face is tensely stretched. A means which does not energize the screen 38 in the non-loaded mode and energize the screen 38 downward in the loaded mode in which an upward load is applied to the screen 38, is provided above the screen 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a transfer head for collectively transferring flux to a wafer or a substrate in advance in a ball mounting apparatus for mounting solder balls or solder bumps on a wafer or a substrate at a time.

[0002]

2. Description of the Related Art In a conventional solder ball mounting apparatus, a projection is provided on the lower surface of a transfer head using a screen, that is, a film-like (plate-like or sheet-like) type, as a new method of transferring fine flux over a wide range. There is a transfer head in which an object is tensioned. However, in this method, when the transfer head is pressed against the flux supply unit 16 as shown in FIG. 8, a phenomenon occurs in which the center of the screen 38 swells, and the amount of the adhered flux between the center and the periphery of the transfer head is reduced. There was a problem that a difference was caused.

[0003]

According to the present invention, even when the transfer head is pressed against the flux supply section, the phenomenon that the center of the screen rises does not occur, and the adhesion of the flux between the center and the periphery of the transfer head does not occur. An object of the present invention is to solve the above-mentioned problem by providing a transfer head capable of making the amount of adhered flux uniform without causing a difference in the amount.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a transfer head in which a screen provided with a transfer projection on the lower surface is tensioned on a frame on the lower surface of the transfer head. Without energizing the screen,
It is an object of the present invention to provide a transfer head characterized in that a means for applying a downward bias to the screen when an upward load is applied to the screen is provided above the screen.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a solder ball mounting apparatus to which the present invention is applied. The solder ball mounting device includes: a wafer supply unit 1;
It comprises a flux transfer section 2, a ball mount section 3, and a work drive mechanism 4. The transfer head according to the present invention exists in the flux transfer unit 2.

The wafer supply unit 1 includes a supply wafer cassette 5, a carry-out wafer cassette 6, a defective wafer cassette 7, and a clean room scalar type robot 9 for transferring wafers. And a wafer positioning position 8 on the work drive mechanism 4.

As shown in FIG. 2, two CCD cameras 31 are arranged above the wafer positioning position 8 so as to overlap each other in the drawing (only one front camera is shown in the drawing). ), Below, an illuminator 32 facing the wafer is provided. The CCD camera 31 is movable by a motor 33 in a direction parallel to the work drive mechanism 4 (X-axis direction) above the wafer positioning position 8 on the work drive mechanism 4.

The work drive mechanism 4 includes a wafer stage 3
0 is provided, and a two-axis drive mechanism for driving the wafer stage 30 is provided, that is, an X-axis (left-right direction in FIG. 1) and a Θ-axis (rotation direction). The Θ-axis drive mechanism is a drive mechanism whose main role is positioning, while the X-axis drive mechanism has a role of moving the work and a role of positioning.

The wafer stage 30 is moved by an X-axis drive mechanism to a wafer positioning position 8 and a flux transfer position 11.
And the movement between the ball mounting positions 20 can be stopped. The wafer stage 30 is provided with two CCD cameras 23 and 23 'for observing the transfer head 13 and the mount head 25.

The flux transfer section 2 includes a transfer head 13 and a drive mechanism thereof, a flux supply device 10, a flux transfer position 11 on a work drive mechanism 4, and a transfer head 13 provided on a moving path of the transfer head 13. And a cleaning unit 12.

A feature of the present invention resides in the transfer head 13. The transfer head 13 is configured such that a screen 38 provided with a large number of transfer protrusions 40 that match the pad pattern downward is tensioned on a frame 39 on the lower surface of the transfer head 13. The flux of the flux supply unit 16 is supplied to the transfer projection 40, and the flux is transferred to the work after the movement.

The frame 39 has a rectangular shape as shown in FIGS. 5 and 6, and has four arrangement grooves 41 for the balance plate 14 on the upper side inside the center of each side.
The balance plate (weight) 14 is arranged in the arrangement groove 41. When the transfer head 13 is pressed against the flux supply unit 16, the balance plate 14 prevents the central portion of the screen 38 from rising as shown in FIG. 8 by using the weight of the balance plate 14. It should be noted that the air pressure may be used instead of the balance plate 14 as an air cylinder type.

As shown in FIGS. 5 and 6, the frame 39 is provided with four retaining projections 37 above the balance plate 14 so that the balance plate 14 can move up and down in the transfer head 13. Have been. Further, the balance plate 14 is provided with height adjusting screws 36 at four positions on the balance plate 14 to slightly make the balance plate 14 above the surface of the screen 38 in a no-load state.

The height adjusting screw 36 is provided on the balance plate 1.
The lower limit position of 4 is adjusted, and the height adjustment screw 3
The height of the lower end portion 6 is adjusted by the amount of protrusion of the lower end portion from the lower surface of the balance plate 14. Thus, the screen 38 is not urged when the balance plate 14 is not loaded, and the screen 38 is urged downward when an upward load is applied to the screen 38. When no load is applied to the balance plate 14, the screen 38 is not biased, thereby preventing the tension life of the screen 38 from being shortened.

As shown in FIG. 3, the transfer head 13 has a Y-axis moving between the flux supply device 10 and the flux transfer position 11 on the work driving mechanism 4 and the cleaning unit 12, and a Z-axis (elevating / lowering). ) Is provided.

In the figure, reference numeral 34 denotes a Z-axis drive motor of the transfer head 13, and reference numeral 34 'denotes a Y-axis drive motor. The Y-axis driving mechanism here is also used for positioning the transfer head 13 and the work.

The flux supply device 10 is provided with a flat flux leveling portion, and the squeegee 15 can level the flux to a constant thickness. A flux supply section 16 corresponding to the flux transfer area 42 of the transfer head 13 is formed in the flux leveling section. The flux supply unit 16 is driven by a servo motor (not shown).
It can be moved up and down by a predetermined amount, and rises when the flux is transferred to the transfer head 13.

The ball mounting section 3 includes a mounting head 2
5 and its driving mechanism, a ball supply device 19, a ball mounting position 20 on the work driving mechanism 4, an excess ball removing device 21 disposed therebetween, a ball suction error inspection device, and a ball suction error inspection device. And a ball discharge device 24 that enters below the mount head 25 when an excess ball is detected.

The ball supply device 19 is configured as a parts feeder, and a vibrator is attached to a ball tray 27 that supplies solder balls to the mount head 25. The vibration of the vibrator causes the solder ball to jump up obliquely upward, and when viewed from above, the solder ball moves around the inside of the ball tray 27.

Above the ball tray 27, a supply port 28 for supplying solder balls from the ball stocker (not shown) into the ball tray 27 is arranged so as to be able to advance and retreat.
A sensor 29 for detecting the remaining amount of the ball in the ball tray 27 is attached to the tip of the supply port 28, and when a shortage of the remaining amount of the ball is detected, a fixed amount of the solder ball is supplied from the ball stocker. The supply port 28 is structured so as to be retracted outside the ball tray 27 in order to avoid interference with the mount head 25 when the solder ball is sucked.

The surplus ball removing device 21 is a removal nozzle for removing excess balls adsorbed on the mount head 25.

As shown in FIG. 4, the mount head 25 has a Y-axis reciprocating between the ball supply device 19 and a ball mount position 20 on the work drive mechanism 4, and a Z-axis (elevation axis). A drive mechanism for the shaft is provided. In the figure, reference numeral 35 denotes a Z-axis drive motor, and reference numeral 35 'denotes a Y-axis drive motor. The Y-axis driving mechanism here is used for positioning the mount head 25 and the work together with the role of the movement of the mount head 25.

The ball suction error inspection apparatus detects a suction error such as a missing ball or an extra ball (excess ball) and a remaining ball which is a mounting error by using four line CCD cameras 22 and 22 '.

Hereinafter, an operation procedure of the solder ball mounting apparatus according to the present embodiment will be described. First, the robot 9 supplies wafers one by one from the supply wafer cassette 5 onto the wafer stage 30 at the wafer positioning position 8. When a wafer is supplied, the wafer stage 30 starts vacuum suction through a hole on the upper surface of the wafer stage 30 through a blower motor (not shown) to hold the wafer.

For the held wafer, target marks or wiring patterns are read by two CCD cameras 31 disposed above the wafer positioning position 8, and the position on the wafer stage 30 is recognized. Data is sent to the control unit. The wafer stage 30 for which the wafer position recognition has been completed is sent to the flux transfer position 11. At this time, the wafer stops at a position that takes into account the deviation of the X axis stored at the time of wafer positioning.

Next, in the flux supply device 10, the flux surface is leveled by the squeegee 15,
Is lowered, the transfer projections 40 of the screen 38 come into contact with the flux supply unit 16, and when an upward load is applied from the flux supply unit 16 to the screen 38, the screen 38 tends to curve upward. However, at this time, the balance plate 1 is located slightly above the screen 38.
4 is located, the screen 38 is the balance plate 1
4, the flux is uniformly attached to the flux transfer projections 40 without causing a swelling phenomenon. After the completion of the supply of the flux, the lowering of the transfer head 13 is stopped and the transfer head 13 is raised.

Thereafter, the wafer is moved to the flux transfer position 11, and the alignment marks of the transfer head 13 are recognized by the two CCD cameras 23 and 23 'provided on the wafer stage 30. The position of the wafer and the transfer head 13 are aligned with one axis (Y axis) of the transfer head 13 and two axes (X axis, Θ axis) of the wafer stage 30 by adding the position data of the previously recognized wafer to the recognition result. The alignment is performed as follows.

After the alignment, the transfer head 13 is lowered. When the load on the transfer head 13 reaches a certain value, it is determined that the transfer is completed, and the transfer head 13 is raised. After ascending, the transfer head 13 returns to the flux supply device 10,
The wafer stage 30 moves to the ball mounting position 20.

On the other hand, the mount head 25 descends from above the ball supply device 19 and stops at a designated position, and applies a suction force from a blower motor (not shown) to the mount head 25 to attract the solder balls to the lower surface of the mount head 25. Let it. When the internal pressure of the mount head 25 becomes lower than the predetermined pressure, it is determined that the suction is completed, and the mount head 25 is raised. After that, the surplus balls are removed by the surplus ball removing device 21 and the apparatus moves to the ball suction error inspection device.

If there is a ball suction error, if the ball is a missing ball, it is moved to the ball supply device 19 again and the suction operation is repeated. If there is an excess ball, the ball discharge device 24 enters below the mount head 25, discharges all the suction balls into the ball discharge device 24, moves to the ball supply device 19 again, and repeats the suction operation.

If there is no abnormality, the ball is moved to the ball mounting position 20. At the ball mounting position 20, the CCD cameras 23, 2
At 3 ', the alignment mark on the lower surface of the mount head 25 is recognized, and positioning is performed in the same manner as the flux transfer position. After the positioning, the mount head 25 descends, mounts the solder balls on the wafer at the ball mounting position 20, and then moves up.

After the mounting of the solder balls is completed, the wafer stage 30 returns to the wafer positioning position 8, and the mounting state of the solder balls on the wafer is inspected by the CCD camera 31 previously moved to the ball mounting inspection position.

At this time, the CCD camera 31 is stopped, and the movement of the wafer stage 30 causes the CCD camera 31 to move.
Scans the entire surface. As a result of the inspection, if the mount is good, the robot 9 inserts it into the unloading wafer cassette 6 if the mount is not good, and into the defective wafer cassette 7 if the mount is bad.

[0034]

According to the present invention, in a transfer head in which a screen provided with transfer projections on the lower surface is stretched by applying tension to a frame on the lower surface of the transfer head, the screen is not urged in a no-load state, and the screen is moved upward. When the transfer head is pressed against the flux supply unit, a phenomenon in which the center of the screen rises when the transfer head is pressed against the flux supply unit occurs by providing a means for applying a downward bias to the screen when a load is applied. As a result, there was no difference in the amount of applied flux between the center and the periphery of the transfer head, and a transfer head capable of making the amount of applied flux uniform could be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a solder ball mounting device.

FIG. 2 is an explanatory view showing a CCD camera for inspection at a wafer positioning position.

FIG. 3 is a side view of a flux transfer unit.

FIG. 4 is a side view of a ball mount unit.

FIG. 5 is an explanatory cross-sectional view showing a state where the transfer head and the flux supply unit are not in contact with each other;

FIG. 6 is a plan view showing a mounting position of a balance plate.

FIG. 7 is an explanatory cross-sectional view showing a state where a transfer head and a flux supply unit are in contact with each other;

FIG. 8 is an explanatory sectional view of a state in which the screen is raised.

[Explanation of symbols]

 1. . . . . . . . 1. Wafer supply unit . . . . . . . Flux transfer unit 3. . . . . . . . Ball mount part 4. . . . . . . . Work drive mechanism 5, 6, 7. . . . 7. Wafer cassette . . . . . . . 8. Wafer positioning position . . . . . . . Robot 10. . . . . . . Flux supply device 11. . . . . . . 11. Flux transfer position . . . . . . Cleaning unit 13. . . . . . . Transfer head 14. . . . . . . Balance plate 15. . . . . . . Squeegee 16. . . . . . . Flux supply unit 19. . . . . . . Ball supply device 20. . . . . . . Ball mount position 21. . . . . . . Excess ball removing device 22, 22 ', 23, 23', 31. . . CCD camera 24. . . . . . . Ball discharge device 25. . . . . . . Mount head 27. . . . . . . Ball tray 28. . . . . . . Supply port 29. . . . . . . Sensor 30. . . . . . . Wafer stage 32. . . . . . . Illuminators 33, 34, 34 ', 35, 35'. . . Motor 36. . . . . . . Height adjustment screw 37. . . . . . . Detachment protrusion 38. . . . . . . Screen 39. . . . . . . Frame 40. . . . . . . Transfer projection 41. . . . . . . Arrangement groove 42. . . . . . . Flux transfer area

Claims (1)

[Claims] In a transfer head in which a screen provided with transfer projections on a lower surface is tensioned on a frame on a lower surface of the transfer head, the screen is not biased in a no-load state.
A transfer head, characterized in that a means for applying a downward bias to the screen when an upward load is applied to the screen is provided above the screen.