JP4243745B2 - Head and workpiece positioning device and positioning method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a head and workpiece positioning device and a positioning method used in a ball mounting apparatus for mounting a solder ball, a solder bump or the like on a wafer or a substrate.
[0002]
[Prior art]
In the conventional solder ball mounting apparatus, positioning is performed by fixing the posture of the mount head and the flux transfer head and matching the posture of the workpiece with the posture of the head. For this reason, there is no posture recognition means on the head side, and only the posture recognition means of the workpiece exists. However, due to the recent trend toward finer balls and the massive mounting of a large number of balls, the required positioning accuracy has dramatically increased, and mounting quality can no longer be ensured by recognizing the position of the head and workpiece using conventional methods. I came.
[0003]
[Problems to be solved by the invention]
In order to solve the above problems, the present invention provides a positioning alignment mark on the head side, recognizes both the head posture and the workpiece posture, and performs positioning based on both recognition results. An object of the present invention is to provide a positioning device and a ball mounting device equipped with a positioning method that can meet the demand for high positioning accuracy due to the flow of ball formation and mass ball mounting.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a head provided with an alignment mark, first optical system recognition means for recognizing the alignment mark, second optical system recognition means for recognizing the posture of a workpiece, Calculation means for calculating the amount of relative displacement between the head and the workpiece from the recognition results of the first optical system recognition means and the second optical system recognition means, and driving of each axis of the head and the workpiece based on the result of the calculation means The present invention provides a head and workpiece positioning device in a ball mount device characterized by having control means for commanding movement to a mechanism.
[0005]
The second invention is substantially the same as the first invention, and the first optical system recognition means provides a head and workpiece positioning device provided on a stage for moving and positioning the workpiece. To do.
[0006]
In the third invention, the alignment mark provided on the head is recognized by the first optical system recognition unit, the posture of the workpiece is recognized by the second optical system recognition unit, and the first optical system recognition unit and the second optical system recognition unit The calculation means calculates the relative displacement between the head and the workpiece from the recognition result of the optical system recognition means, and commands the movement mechanism from the control means to the drive mechanism of each head and workpiece based on the result of the calculation means. Thus, there is provided a method for positioning a head and a workpiece in a ball mount device characterized by positioning the head and the workpiece.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described together with examples according to the drawings. FIG. 1 is a plan view of a solder ball mounting apparatus in which the present invention is implemented. The solder ball mount apparatus includes a wafer supply unit 1, a flux transfer unit 2, a ball mount unit 3, and a work drive mechanism 4.
[0008]
In this embodiment, the workpiece is a wafer, and the wafer supply unit 1 carries the wafers, including the wafer cassette 5 for supply, the wafer cassette 6 for unloading, and the wafer cassette 7 for failure, and the wafer. A clean room scalar type robot 9 and a wafer positioning position 8 on the work drive mechanism 4 are provided.
[0009]
Above the wafer positioning position 8, as shown in FIG. 2, two CCD cameras 31 serving as the second optical system recognizing means in the present invention are arranged so as to overlap each other in the drawing (in the drawing, An illuminator 32 facing the wafer is disposed below the front one). The CCD camera 31 can be moved by the motor 33 in the direction parallel to the work drive mechanism 4 (X-axis direction) above the wafer positioning position 8 on the work drive mechanism 4.
[0010]
The workpiece drive mechanism 4 is provided with a wafer stage 30, and is provided with a two-axis drive mechanism for driving the wafer stage 30, that is, an X axis (left and right direction in FIG. 1) and a Θ axis (rotation direction). The Θ-axis drive mechanism is a drive mechanism adopted as a main role for positioning, but the X-axis drive mechanism has a role of workpiece movement and a role of positioning.
[0011]
The wafer stage 30 can be stopped from moving between the wafer positioning position 8, the flux transfer position 11, and the ball mount position 20 by an X-axis drive mechanism. In the embodiment, the head in the present invention is a flux transfer head 13 and a solder ball mount head 25. 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 CCD cameras 23 and 23 'serve as the first optical system recognition means in the present invention.
[0012]
The ball mount device in this embodiment includes an arithmetic unit (not shown) that calculates a relative displacement amount from the posture of the workpiece by the CCD camera 31 and the recognition result of the head alignment mark 17 by the CCD cameras 23 and 23 '. And a control device (not shown) for instructing movement or rotation to the driving mechanism of each axis (Y axis, X axis, Θ axis) of the head and the workpiece based on the result of the arithmetic unit. .
[0013]
The flux transfer unit 2 includes a transfer head 13 and a driving mechanism thereof, a flux supply device 10, and a flux transfer position 11 on the work driving mechanism 4, and a cleaning unit 12 of the transfer head 13 is disposed in a moving path of the transfer head 13. Is provided.
[0014]
As shown in FIG. 5, alignment marks (positioning marks) 17 are provided on the head lower surface 40 of the transfer head 13 at four positions on the outer side near the outline of the wafer. The alignment mark 17 is formed by providing a recess having a diameter of 0.3 mm at the center of a protrusion having a diameter of 10 mm. The protrusions are made of the same material and process as the flux transfer protrusions 18. Note that the alignment mark 17 ′ may be formed in a portion where the flux transfer projection 18 does not exist at a position corresponding to the inside of the wafer lower surface 40 of the transfer head 13 near the contour of the wafer.
[0015]
As shown in FIG. 3, the transfer head 13 of the flux supply device 10 includes a Y axis that reciprocates between the flux supply device 10 and the flux transfer position 11 on the work drive mechanism 4, and a Z axis (elevating shaft). The two-axis drive mechanism is provided. In the figure, 34 is a Z-axis drive motor of the transfer head 13, and 34 'in the figure is a Y-axis drive motor. The Y-axis drive mechanism here is used not only for the movement of the transfer head 13 but also for positioning the transfer head 13 and the workpiece.
[0016]
The flux supply device 10 is provided with a flat flux leveling unit, and the squeegee 15 can level the flux to a certain thickness. In the flux leveling portion, a flux supply portion 16 corresponding to the flux transfer region of the transfer head 13 is formed.
[0017]
The ball mount unit 3 includes a mount head 25 and its drive mechanism, a ball supply device 19, a ball mount position 20 on the work drive mechanism 4, a surplus ball removing device 21 disposed therebetween, and a ball suction error inspection device. And a ball discharge device 24 that enters under the mount head 25 when an excess ball is detected by the ball suction error inspection device.
[0018]
As shown in FIGS. 6 and 7, alignment marks 17 ′ are provided on the head lower surface 41 of the mount head 25 at four positions on the outer side near the outline of the wafer where the suction holes 26 do not exist. The alignment mark 17 'is formed by a recess having a diameter of 0.3 millimeter. The alignment mark 17 ′ may be formed in a portion where the suction hole 26 does not exist at a position corresponding to the inside of the wafer lower surface 41 near the contour of the wafer.
[0019]
The ball supply device 19 has a configuration like a parts feeder, and a vibrator is attached to a ball tray 27 that supplies solder balls to the mount head 25. The solder ball is flipped up obliquely by vibration of the vibrator, and the solder ball moves so as to go around in the ball tray 27 when observed from above.
[0020]
Above the ball tray 27, a supply port 28 for supplying solder balls from a ball stocker (not shown) into the ball tray 27 is disposed so as to freely advance and retract. A sensor 29 for detecting the remaining amount of balls in the ball tray 27 is attached to the tip of the supply port 28, and when a shortage of remaining balls is detected, a certain amount of solder balls are supplied from the ball stocker. The supply port 28 has a structure for retracting outside the ball tray 27 to avoid interference when the mount head 25 attracts the solder ball.
[0021]
The surplus ball removing device 21 is a removal nozzle for removing surplus balls adsorbed on the mount head 25.
[0022]
As shown in FIG. 4, the mount head 25 is driven in two axes: a Y axis that reciprocates between the ball supply device 19 and the ball mount position 20 on the work drive mechanism 4, and a Z axis (elevating axis). A mechanism is provided. In the figure, 35 is a Z-axis drive motor, and 35 'in the figure is a Y-axis drive motor. The Y-axis drive mechanism here is used not only for the movement of the mount head 25 but also for positioning the mount head 25 and the workpiece.
[0023]
The ball adsorption error inspection device detects an adsorption error such as a missing ball or an extra ball (excess ball) and a main ball that is a mounting error by the four line CCD cameras 22 and 22 '.
[0024]
Hereinafter, an operation procedure of the solder ball mounting device according to the present embodiment will be described. First, wafers are supplied one by one from the supply wafer cassette 5 to the wafer stage 30 at the wafer positioning position 8 by the robot 9. In the wafer stage 30, when a wafer is supplied, vacuum suction is started from a hole on the upper surface of the wafer stage 30 through a blower motor (not shown) to hold the wafer.
[0025]
The held wafer is recognized by extracting a positioning mark or a circuit pattern formed on the wafer surface by the CCD camera 31 which is two second optical system recognition means arranged above the wafer positioning position 8. When the position of the wafer on the wafer stage 30 is recognized, data is sent to an arithmetic unit (not shown). After the wafer position recognition is completed, the wafer stage 30 is sent to the flux transfer position 11. At this time, it stops at a position that takes into account the X-axis deviation stored during wafer positioning.
[0026]
Next, in the flux supply device 10, the flux surface is leveled by the squeegee 15, the transfer head 13 is lowered, the transfer head 13 and the flux supply unit 16 come into contact, and a load of a predetermined pressure or higher is applied. It is determined that the transfer has ended, and the transfer head 13 stops descending and rises.
[0027]
Thereafter, the wafer moves to the flux transfer position 11, and the alignment marks 17 on the lower surface 40 of the transfer head 13 are recognized by the CCD cameras 23, 23 ′ which are two first optical system recognition means provided on the wafer stage 30. . In the arithmetic unit, the position data of the wafer recognized previously is added to the recognition result, and the relative displacement amount is calculated from the recognition result of both.
[0028]
In response to the calculation result, the control device issues a command to align the position of the wafer and the transfer head 13 with respect to one axis (Y axis) of the transfer head 13 and two axes (X axis, Θ axis) of the wafer stage 30. Based on this, the Y axis of the transfer head 13, the X axis and the Θ axis of the wafer stage 30 are operated to perform alignment.
[0029]
After the alignment, the transfer head 13 is lowered, and when the load on the Z-axis drive motor 34 of the transfer head 13 reaches a certain value, it is determined that the transfer is finished, and the transfer head 13 is raised. After rising, the transfer head 13 returns to the flux supply device 10 and the wafer stage 30 moves to the ball mount position 20.
[0030]
On the other hand, the mount head 25 descends from above the ball supply device 19 and stops at a specified position. A suction force is applied to the mount head 25 from a blower motor (not shown), and the solder balls are placed in the suction holes 26 on the lower surface of the mount head 25. Adsorb. When the internal pressure of the mount head 25 becomes lower than a predetermined pressure, it is determined that the suction is completed, and the mount head 25 is raised. Thereafter, the surplus balls are removed by the surplus ball removing device 21 and moved to the ball suction error inspection device.
[0031]
If there is a ball suction mistake, if it is a missing ball, it moves to the ball supply device 19 again and repeats the suction operation. If there are surplus balls, the ball discharge device 24 enters under the mount head 25, discharges all the suction balls into the ball discharge device 24, and then moves to the ball supply device 19 again to repeat the suction operation.
[0032]
If there is no abnormality, it moves to the ball mount position 20. At the ball mount position 20, the alignment marks 17 ′ on the head lower surface 41 of the mount head 25 are recognized by the CCD cameras 23, 23 ′ as first optical system recognition means provided on the wafer stage 30. In the arithmetic unit, the position data of the wafer recognized previously is added to the recognition result, and the relative displacement amount is calculated from the recognition result of both.
[0033]
In response to this calculation result, the control device issues a command to align the position of the wafer and the mount head 25 with respect to one axis (Y axis) of the mount head 25 and two axes (X axis, Θ axis) of the wafer stage 30. Based on this, the Y axis of the mount head 25, the X axis and the Θ axis of the wafer stage 30 operate to perform positioning. After positioning, the mount head 25 descends, mounts solder balls on the wafer at the ball mount position 20, and then ascends.
[0034]
After the mounting of the solder balls, the wafer stage 30 returns to the wafer positioning position 8, but the mounting state of the solder balls on the wafer is inspected by the CCD camera 31 that has been moved to the ball mounting inspection position in advance. The CCD camera 31 has a main purpose of recognizing the posture of the workpiece as the second optical system recognizing means. However, in the embodiment, it also has a role of inspecting the mounting state of the solder balls on the wafer.
[0035]
When inspecting the mounting state, the CCD camera 31 is stopped, and the entire surface is scanned by the CCD camera 31 as the wafer stage 30 moves. If the result of the inspection is that the mount is good, the robot 9 inserts it into the wafer cassette 6 for unloading, and if the mount is bad, it is inserted into the wafer cassette 7 for failure.
[0036]
【The invention's effect】
The present invention provides a head provided with an alignment mark, a first optical system recognizing means for recognizing the alignment mark, a second optical system recognizing means for recognizing the posture of the work, and a recognition result of both recognizing means. And a positioning means and a positioning method for a head, a calculation means for calculating a relative positional deviation amount of the workpiece, and a control means for commanding movement to the driving mechanism of each axis of the head and the workpiece based on the result of the calculation means For this reason, it has become possible to meet the demands for high positioning accuracy due to the flow of finer balls and the mass loading of a large number of balls.
[0037]
According to the second aspect of the invention, the first optical system recognition means is provided on the stage for moving and positioning the workpiece, thereby recognizing the head alignment mark using the workpiece drive mechanism. As a result, the transfer head and mount head can be recognized with a small number of drive mechanisms, and the entire ball mount apparatus can be reduced in size.
[Brief description of the drawings]
FIG. 1 is a plan view of a solder ball mounting apparatus. FIG. 2 is an explanatory view showing an inspection CCD camera at a wafer positioning position. FIG. 3 is a side view of a flux transfer unit. 5] Cross-sectional explanatory view showing the lower surface of the transfer head. [Fig. 6] Cross-sectional explanatory view showing the lower surface of the mount head. [Fig. 7] Explanatory drawing showing alignment marks on the lower surface of the mount head.
1. . . . . . . . 1. Wafer supply unit . . . . . . . 2. Flux transfer part . . . . . . . 3. Ball mount part . . . . . . . Work drive mechanism 5, 6, 7. . . . Wafer cassette8. . . . . . . . Wafer positioning position9. . . . . . . . Robot 10. . . . . . . 10. Flux supply device . . . . . . Flux transfer position 12. . . . . . . Cleaning unit 13. . . . . . . Transfer head 15. . . . . . . Squeegee 16. . . . . . . Flux supply unit 17, 17 '. . . Alignment mark 18. . . . . . . Transfer protrusion 19. . . . . . . Ball supply device 20. . . . . . . Ball mount position 21. . . . . . . Surplus ball removing devices 22, 22 ', 23, 23', 31. . . CCD camera 24. . . . . . . Ball ejector 25. . . . . . . Mount head 26. . . . . . . Adsorption hole 27. . . . . . . Ball tray 28. . . . . . . Supply port 29. . . . . . . Sensor 30. . . . . . . Wafer stage 32. . . . . . . Illuminators 33, 34, 34 ', 35, 35'. . . Motors 40, 41. . . . Head bottom

Claims (3)

A head provided with an alignment mark, a first optical system recognizing unit for recognizing the alignment mark, a second optical system recognizing unit for recognizing the posture of the workpiece, a first optical system recognizing unit, and a second optical system recognizing unit Computation means for computing the relative displacement between the head and the workpiece from the recognition result with the optical system recognition means, and control means for commanding movement to the drive mechanism of each axis of the head and workpiece based on the result of the computation means An apparatus for positioning a head and a workpiece in a ball mount device. 2. The head and workpiece positioning apparatus according to claim 1, wherein the first optical system recognition means is provided on a stage for moving and positioning the workpiece. An alignment mark provided on the head is recognized by the first optical system recognition means, the posture of the workpiece is recognized by the second optical system recognition means, and the first optical system recognition means and the second optical system recognition means are The relative displacement between the head and the workpiece is calculated by the calculation means from the recognition result, and based on the result of the calculation means, the control means instructs the drive mechanism of each axis of the head and the workpiece to move. A method for positioning a head and a workpiece in a ball mount device, wherein the positioning is performed.

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