JP2990982B2 - Method of Aligning Collet of Transfer Head and Pin of Die Ejector in Die Bonder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of 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 to a substrate.

[0002]

2. Description of the Related Art A die bonder pushes up a chip on a wafer sheet by a pin of a die ejector disposed below the wafer sheet, vacuum-adsorbs the pushed-up chip to a collet of a transfer head, and picks up the chip. It is designed to be mounted at a predetermined position on a substrate such as a printed circuit board.

In the die bonder, it is necessary to match the center of the pin with the center of the collet arriving above the die ejector. If they do not match, a chip pick-up error occurs or the collet moves downward. When the chip is vacuum-sucked, the inner surface of the collet collides with the edge of the chip to damage 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 pins are aligned.

Conventionally, this alignment has been performed as follows. First, after retreating the wafer sheet located above the die ejector, observe the pins of the die ejector with the camera above, and observe the origin point of the camera (optical reference point, for example, the optical axis of the camera). Detect the center coordinates of the pin. Next, the wafer sheet is arranged above the die ejector, and the wafer sheet is moved in the X direction or the Y direction so that the center of any chip on the wafer sheet is aligned 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 with the chip.

FIG. 5 shows how this alignment is performed. A large number of chips 2 are adhered on the wafer sheet 1, and the chips 2 are pushed up from below by the pins 4 of the die ejector 3. This ejector 3
The pin 4 is arranged inside the vertical cylinder 5, and a cap 6 is covered on the upper part of the vertical cylinder 5. By driving driving means (not shown) such as a motor, a link and a cam, the pin 4 is driven.
Is moved upward, the pins 4 are projected from the holes 7 formed in the center of the cap 6, and the chips 2 on the wafer sheet 1 are pushed up. Transfer head 9
Is held by a Y table 10, and by driving an X table (not shown) and the Y table 10, the transfer head 9 is moved in a horizontal direction, and a collet 11 provided below the transfer head 9 is provided. Is positioned above the chip 2. Then, as shown in FIG.
The operator moves the X table and the Y table 10 while moving the collet 11 in the X direction and the Y direction while visually recognizing the operator, thereby aligning the collet 11 with the pins 4. When the alignment between the collet 11 and the pins 4 is completed in this way, the operation for mounting the chips 2 on the wafer sheet 1 on a substrate (not shown) is started.

[0006]

However, in the above-mentioned conventional method, as shown in FIG. 5, the operator performs alignment while visually checking the collet 11 and the chip 2 with the microscope 12, so that much labor and time are required. Further, there has been a problem that it is extremely difficult to automate the alignment of the pin and the collet with such means. Incidentally, the accuracy required for this alignment is generally about 10 μm.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of aligning a collet of a transfer head and a pin of a die ejector in a die bonder which can automatically and quickly align a collet with a pin.

[0008]

For this purpose, the present invention comprises a step of vacuum-adhering a chip to a collet, mounting the chip on a cap of a die ejector, releasing the vacuum-adsorbed state, and retracting the collet from above the die ejector. Observing the chip mounted on the cap in the above step with an upper camera to obtain the center coordinates of the chip; moving the collet to above the chip on the cap, picking up the chip by vacuum suction and picking up the die. Removing the ejector from the ejector, observing the pins of the ejector with a camera to determine the center coordinates thereof, and determining the center coordinates of the chip and the center coordinates of the pins determined in the X and Y directions. Calculating the relative displacement and registering it in a 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 construction, the relative displacement between the center coordinates of the collet and the center coordinates of the pins in the X and Y directions can be easily and accurately determined, so that the chips on the wafer are mounted on the substrate. In this case, the center coordinates of the collet are made to match the center coordinates of the pins by correcting the movement amount of the transfer head in the X direction and the Y direction based on the amount of displacement, so that the chips on the wafer sheet can be reliably located. Can be picked up.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall perspective view of a die bonder. The same components as those of the conventional example shown in FIG. The transfer head 9 is held at the tip of a Y table 10. Y table 10
An X table 13 is disposed orthogonally above, and when the X direction motor MX1 and the Y direction motor MY1 are driven, the transfer head 9 moves horizontally in the X direction and the Y direction. The X table 13 and the Y table 10 are provided on support posts 17 a installed on a base 17.

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

The wafer sheet 1 is mounted on a table 16. The table 16 is arranged on the X table 20, and the X table 20 is arranged on the Y table 21 at right angles thereto. By driving the X-direction motor MX2 and the Y-direction motor MY2, the wafer sheet 1 can be positioned directly above the die ejector 3, or can be moved laterally from directly above the die ejector 3. The die ejector 3 is installed on a 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 moving the collet 11 up and down, a collet 11
A motor Mθ for rotating the shaft 9a via the belt 9b and the gears 9c and 9d to set the rotation angle of the chip 2 vacuum-adsorbed to the collet 11 is housed. FIG. 2 is a block diagram of the 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 displacement between the chip 2 and the pin 4, and controls the motors MX 1, MY 1, M 1 via the motor driving circuits 33 to 38.
X2, MY2, Mθ, and MZ are controlled. This die bonder is configured as described above. Next, a method for aligning the collet 11 and the pin 4 will be described with reference to FIG.

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

Next, as shown in FIG.
Is released, 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. The center coordinates (X1, Y
1) can be easily obtained by a well-known image processing method, and its value is registered in the memory 32.

Next, as shown in FIG. 3 (c), the collet 11 is moved again above the die ejector 3, the chip 2 on the cap 6 is picked up, and the chip 2 is removed from the cap 6. The pin 4 is observed by the camera 18 and its center coordinates (X2, Y2) are obtained. In this case, the pin 4 may be projected from the cap 6 and observed with the camera 18 as shown in the drawing, or may be observed through the pin hole 7 while being lowered into the cap 6. The center coordinates (X2, Y2) are also stored in the memory 32.
Registered in.

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 displacement amount ΔX = X1−X2 in the X direction and the displacement 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 (X1, Y1) of the pin 4 and the center coordinates (X2,
When the relative displacement amounts ΔX and ΔY of Y2) are obtained, the operation of mounting the chips 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, the X table 13 and the Y table 10 are driven, and the collet 11 of the transfer head 9 is placed directly above the pins 4 of the die ejector 3. Then, the chip 2 is picked up by causing the collet 11 to move up and down, and then the transfer head 9 is moved above the substrate 15, and the collet 11 is again moved up and down there. Is mounted on the substrate 15. By repeating such operations, the chips 2 on the wafer sheet 1 are mounted on the substrate 15 one after another.
In this case, the X direction and Y obtained in advance as described above are used.
If the moving amount of the transfer head 9 by driving the X table 13 and the Y table 10 is corrected based on the positional deviation amounts ΔX and ΔY in the directions, the center of the collet 11 and the center of the pin 4 are accurately matched, and the chip 2 can be reliably picked up.

The present invention is not limited to the above embodiment. For example, in FIG. 3, the chip 2 vacuum-adsorbed to the collet 11 may be a dummy chip. 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. May be. Further, FIGS. 3A and 3B
The order shown in (c) may be reversed. That is, FIG.
As shown in FIG. 3C, first, the center coordinates (X2, Y2) of the pin 4 are obtained by the camera 18, and then, as shown in FIGS.
The center coordinates (X1, Y1) may be obtained by mounting the chip 2 on the cap 6 as shown in FIG.
The point is that the relative displacement between the center of the collet 11 and the center of the pin 4 in the X and Y directions may be detected.

[0021]

As described above, according to the present invention, the relative displacement between the center coordinates of the collet and the center coordinates of the pin in the X and Y directions can be obtained easily and accurately. When the chips on the sheet are mounted on the substrate, the amount of displacement of the transfer head in the X and Y directions is corrected based on the amount of displacement, so that the center of the collet matches the center of the pin, and the wafer sheet is adjusted. The upper chip can be reliably picked up.

[Brief description of the 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 one embodiment of the present invention.

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

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 operation.

[Explanation of symbols]

 Reference Signs List 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)

(57) [Claims] In a die bonder, a chip on a wafer sheet is pushed up by a pin of a die ejector arranged below the wafer sheet, the chip is vacuum-adsorbed to a collet of a transfer head, picked up, and transferred and mounted on a substrate. Vacuum adsorbing the chip onto the collet and mounting it on the cap of the die ejector, releasing the vacuum suction state and retracting the collet from above the die ejector; and Observing the center coordinates of the chip by observing the chip, moving the collet above the chip on the cap, vacuum-adsorbing the chip, picking it up, and removing it from the die ejector, observing the die ejector pin with a camera Determining the center coordinates by using Calculating a relative displacement amount of the center coordinates of the chip and the center coordinates of the pin in the X direction and the Y direction obtained in the above, and registering the amount in a computer. How to align the collet and pin of the ejector.