JPH06163611A - Method for aligning transfer head collet with die ejector pin of die bonder - Google Patents

Abstract

PURPOSE:To automatically and rapidly align a collet with a pin by easily and accurately obtaining relative displacement amount, in X and Y direction, in the center coordinate of a collet and a pin. CONSTITUTION:A collet 11 and a chip 2 are made to land an a cap 6. The collet 11 is made to escape sideward, and the chip 2 is mounted on the cap 6. Then, by using a camera 18, the chip 2 is observed, for obtaining its center coordinate. The center coordinate is registered in a memory 32. Then, the collet 11 is shifted toward above a die ejector 3, for observation of a pin 4 with the camera 18. Its center coordinate is obtained, and is registered in the memory 32. Based upon relative displacement amount between the center coordinates of the pin 4 and the collet 11, the shifted amount of a transfer head 9, driven by an X table 13 and a Y table 10, is corrected. With this, the centers of collet 11 and pin 4 are aligned accurately, far sure pick up of the chip 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning a collet of a transfer head and a pin of a die ejector in a die bonder for transferring and mounting chips on a wafer sheet onto a substrate.

[0002]

2. Description of the Related Art A die bonder pushes up a chip on a wafer sheet with a pin of a die ejector arranged below the wafer sheet, and vacuum-adheres the pushed up chip to a collet of a transfer head to pick up a lead frame or It is designed to be mounted at a predetermined position on a board such as a printed board.

In the die bonder, it is necessary to match the center of the pin with the center of the collet that has arrived above the die ejector. If this is not the case, a chip pickup error occurs or the collet descends. When the chip is sucked by vacuum, the inner surface of the collet collides with the edge of the chip and damages the edge. Therefore, before the chips on the wafer sheet are mounted on the substrate by the die bonder, the center of the collet and the center of the pin are aligned.

Conventionally, this alignment has been performed as follows. First, after the wafer sheet located above the die ejector is withdrawn, the pins of the die ejector are observed by the camera above and the origin point of the camera (optical reference point, for example, the optical axis of the camera) is measured. Detect the center coordinate of the pin. Next, the wafer sheet is placed above the die ejector, and the wafer sheet is moved in the X and Y directions to align the center of any chip on the wafer sheet with the origin point. Next, the collet of the transfer head is moved above the chip, and then the collet is lowered, and the chip is pushed up by the pin of the die ejector to align the collet and the chip.

FIG. 5 shows how this alignment is performed. A large number of chips 2 are attached on the wafer sheet 1, and the chips 2 are pushed up from below by the pins 4 of the die ejector 3. This die ejector 3
The pin 4 is arranged inside the standing cylinder 5, and the cap 6 is covered on the upper part of the standing cylinder 5. The pin 4 is driven by driving a driving means (not shown) such as a motor, a link or a cam.
The block 8 erected upright is moved upward, the pin 4 is projected from the hole portion 7 opened in the center of the cap 6, and the chip 2 on the wafer sheet 1 is pushed up. Transfer head 9
Are held on the Y table 10, and the X table (not shown) and the Y table 10 are driven to move the transfer head 9 in the horizontal direction, and the collet 11 provided below the transfer head 9 is moved. Is placed above the chip 2. Then, as shown in FIG.
While the operator visually recognizes, the X table and the Y table 10 are driven to move the collet 11 in the X direction and the Y direction, and the collet 11 and the pin 4 are aligned with each other. When the alignment of the collet 11 and the pin 4 is completed in this way, the work of mounting the chip 2 on the wafer sheet 1 on the substrate (not shown) is started.

[0006]

However, in the above-mentioned conventional method, the operator performs alignment while visually observing the collet 11 and the chip 2 with the microscope 12 as shown in FIG. In addition, there is a problem in that it is extremely difficult to automate the alignment of the pin and the collet by such means. Incidentally, the accuracy required for this alignment is generally about 10 μm.

Therefore, it is an object of the present invention to provide a method for aligning a collet of a transfer head and a pin of a die ejector in a die bonder, which can automatically and quickly align the collet and pin.

[0008]

To this end, according to the present invention, a chip is vacuum-sucked to a collet and mounted on a cap of a die ejector, and the vacuum suction state is released to retract the collet from the die ejector. In the above step, the chip mounted on the cap is observed by the camera above to obtain the center coordinates of the chip, and the collet is moved above the chip on the cap, the chip is vacuum sucked and picked up. The step of removing from the ejector, the step of observing the pin of the die ejector with a camera to obtain the center coordinates thereof, and the step of removing the center coordinates of the chip and the center coordinates of the pins obtained as described above in the X and Y directions. In the die bonder, from the step of calculating the relative displacement amount and registering it in the computer, Alignment method of the pin of the collet of the mounting head and the die ejector is obtained by constituting the.

[0009]

According to the above structure, the relative positional deviation amount between the center coordinate of the collet and the center coordinate of the pin in the X and Y directions can be easily and accurately determined, so that the chip on the wafer is mounted on the substrate. At this time, by correcting the movement amount of the transfer head in the X direction and the Y direction based on the positional deviation amount, the center coordinate of the collet is matched with the center coordinate of the pin, and the chip on the wafer sheet is surely secured. You can pick it up.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is an overall perspective view of a die bonder. The same parts as those of the conventional example shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. The transfer head 9 is held at the tip of the Y table 10. Y table 10
The X table 13 is arranged orthogonally on the upper side, and when the X direction motor MX1 and the Y direction motor MY1 are driven, the transfer head 9 horizontally moves in the X direction and the Y direction. The X table 13 and the Y table 10 are provided on a support post 17 a installed on the base 17.

A conveyor 14 is provided on a base 17 below the moving path of the transfer head 9, and a substrate 15 is placed on the conveyor 14. A wafer sheet 1 is arranged on the side of the conveyor 14, and a die ejector 3 is installed below the wafer sheet 1.

The wafer sheet 1 is mounted on the table 16. The table 16 is arranged on the X table 20, and the X table 20 is arranged on the Y table 21 orthogonally thereto. By driving the X-direction motor MX2 and the Y-direction motor MY2, the wafer sheet 1 can be positioned right above the die ejector 3 or can be withdrawn laterally from right above the die ejector. The die ejector 3 is installed on the base 17. A camera 18 is provided above the die ejector 3. Reference numeral 19 denotes a fixing bracket for the camera 18, which is fixed on the base 17.

In FIG. 3, a motor MZ for vertically moving the collet 11 and a collet 11 are provided inside the transfer head 9.
A motor Mθ for setting the rotation angle of the tip 2 vacuum-adsorbed by the collet 11 by rotating the shaft 9a through the belt 9b and the gears 9c and 9d is housed. FIG. 2 is a block diagram of an electric circuit. The camera 19 is connected to the control unit 31 via the image processing unit 30. The image processing unit 30 calculates the center coordinates of the chip 2 and the pin 4. A memory 32 is connected to the control unit 31 and stores necessary data such as programs. The control unit 31 calculates the amount of positional deviation between the chip 2 and the pin 4, and also via the motor drive circuits 33 to 38, the motors MX1, MY1, M.
It controls X2, MY2, Mθ, and MZ. The die bonder is configured as described above. Next, a method of aligning the collet 11 and the pin 4 will be described with reference to FIG.

First, as shown in FIG. 3A, the collet 1
1, the chip 2 is vacuum-adsorbed, the Y table 10 and the X table 13 are driven to move the transfer head 9 above the die ejector 3, and then the collet 11 is lowered to land the chip 2 on the cap 6. (See the chain line in Figure 3). At this time, the wafer sheet 1 is retreated to the side of the die ejector 3.

Next, as shown in FIG. 3B, the collet 11
After releasing the vacuum suction state, the collet 11 is retracted to the side and the chip 2 is mounted on the cap 6. Next, the chip 2 is observed by the camera 18 and its center coordinates (X1, Y1) are obtained. This center coordinate (X1, Y
1) can be easily obtained by a known image processing method, and its value is registered in the memory 32.

Next, as shown in FIG. 3C, the collet 11 is again moved above the die ejector 3 to pick up the chip 2 on the cap 6 and remove the chip 2 from the top of the cap 6. The pin 4 is observed by the camera 18 and its center coordinate (X2, Y2) is obtained. In this case, the pin 4 may be projected from the cap 6 and observed by the camera 18 as shown in the drawing, or may be observed through the pin hole 7 while being lowered inside the cap 6. This center coordinate (X2, Y2) is also stored in the memory 32.
Be registered with.

FIG. 4 shows the relative positional relationship between the center coordinates (X1, Y1) of the collet 11 and the center coordinates (X2, Y2) of the pin 4 obtained as described above. The positional deviation amount ΔX = X1−X2 and the positional deviation amount ΔY = Y1−Y2 in the Y direction are calculated by the image processing unit 30 and registered in the memory 32.

As described above, the center coordinates of the pin 4 (X1, Y1) and the center coordinates of the collet 11 (X2,
When the relative displacement amounts ΔX and ΔY of Y2) are obtained, the work of mounting the chip 2 on the wafer sheet 1 on the substrate 15 is started. That is, as shown in FIG. 1, the wafer sheet 1 is positioned above the die ejector 3, and the X table 13 and the Y table 10 are driven so that the collet 11 of the transfer head 9 is located directly above the pin 4 of the die ejector 3. The chip 2 is picked up by positioning it and causing the collet 11 to move up and down there. Then, the transfer head 9 is moved to above the substrate 15, where the collet 11 moves up and down again to move the chip 2 up and down. Are mounted on the substrate 15. By repeating such an operation, the chips 2 on the wafer sheet 1 are sequentially mounted on the substrate 15.
In this case, the X direction and the Y determined in advance as described above
If the movement amount of the transfer head 9 due to the driving of the X table 13 and the Y table 10 is corrected based on the positional displacement amounts ΔX and ΔY in the direction, the center of the collet 11 and the center of the pin 4 are accurately matched to each other. 2 can be reliably picked up.

The present invention is not limited to the above embodiment, and for example, the chip 2 vacuum-adsorbed by the collet 11 in FIG. 3 may be a dummy chip. Further, in FIG. 1, the die ejector 3 is fixedly installed on the base 17, but the die ejector 3 is supported on an X table or a Y table to move the die ejector 3 in the X direction or the Y direction. But it's okay. Furthermore, FIG. 3 (a) (b)
The order shown in (c) may be reversed. That is, FIG.
As shown in FIG. 3C, first, after the center coordinates (X2, Y2) of the pin 4 are obtained by the camera 18, FIG.
The center coordinates (X1, Y1) of the chip 2 may be mounted on the cap 6 as shown in FIG.
In short, it is sufficient to detect the amount of relative positional deviation between the center of the collet 11 and the center of the pin 4 in the X and Y directions.

[0021]

As described above, according to the present invention, it is possible to easily and accurately determine the relative positional deviation amount between the center coordinates of the collet and the center coordinates of the pin in the X and Y directions. When the chips on the sheet are mounted on the substrate, the center of the collet is matched with the center of the pin by correcting the movement amount of the transfer head in the X and Y directions based on the amount of misalignment, so that the wafer sheet It is possible to reliably pick up the upper chip.

[Brief description of drawings]

FIG. 1 is an overall system diagram of a die bonder according to an embodiment of the present invention.

FIG. 2 is a block diagram of an electric circuit according to an embodiment of the present invention.

FIG. 3 (a) is a side view of a main part of a collet according to an embodiment of the present invention during alignment of a pin. (B) A perspective view of a main part of a collet according to an embodiment of the present invention during alignment with a pin (c) ) A perspective view of a main portion of the embodiment of the present invention during alignment between the collet and the pin

FIG. 4 is a center coordinate diagram of a collet and a pin according to an embodiment of the present invention.

FIG. 5 is an explanatory view during a conventional collet and pin alignment work.

[Explanation of symbols]

 1 wafer sheet 2 chip 3 die ejector 4 pin 6 cap 9 transfer head 10 Y table 11 collet 13 X table 18 camera

Claims (1)

[Claims] 1. A die bonder in which a chip on a wafer sheet is pushed up by a pin of a die ejector disposed below the wafer sheet, the chip is vacuum-sucked and picked up by a collet of a transfer head, and transferred and mounted on a substrate. The chip is vacuum-sucked to the collet and mounted on the die ejector cap, the vacuum suction state is released and the collet is retracted from the die ejector, and the chip mounted on the cap in the above step is taken by the camera above. Observe the chip's center coordinates, move the collet above the chip on the cap, pick up the chip by vacuum suction and remove it from the die ejector, and observe the die ejector pin with a camera. And obtaining the center coordinates thereof, as described above. A transfer head in a die bonder, the step of calculating relative displacement amounts of the center coordinates of the chip and the center coordinates of the pin obtained in the X and Y directions, and registering them in a computer. How to align the collet and die ejector pins.