JPH0521506A - Position detecting device for electronic parts using picture recognizing means - Google Patents

Abstract

PURPOSE:To minimize the influence of optical distortion to the title device by controlling the position of a work so that the reference position of the work can be brought nearer to the optical axis of an optical image pickup means by relatively moving the image pickup means or work after conducting coordinate detection for roughly positioning the reference position of the work. CONSTITUTION:By moving an X-Y table 7, the images of electrode pads E0, E1,... sections are taken with a TV camera 11 and the picture data 34 of the sections are fetched. Then a pattern matching process is executed. When a pattern matches, the position of the pad E0 is roughly detected by calculating the coordinates of the pad E0 with respect to a reference electrode pad P0. Then the coordinates of the rough position of the pad E0 and shifted amount DELTAX1 and DELTAY1 of the optical axis of the camera 11 against coordinates '0' are calculated and, when the shifted amount exceeds an allowable limit, the table 7 is moved by the shifted amount DELTAX1 and DELTAY1. When the shifted amount is within the allowable limit, precise position detection is executed for detecting the position of the electrode pad E0 and the detected position is stored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the position of a work when wire-bonding to a work such as a semiconductor pellet in an electronic component, particularly an integrated circuit.

[0002]

2. Description of the Related Art When wire bonding an electrode pad on an IC pellet (semiconductor pellet) in an integrated circuit (IC) and a lead portion on a lead frame, the wire bonding position (that is, the position of the electrode pad and the tip position of the lead portion). And) are correctly detected in advance, and the bonding head is moved by a DC motor or the like based on the position data obtained thereby.

As the detection method, the following procedure has been executed in the recent technology. That is, the bonding head and the television camera (optical image pickup means) in the image recognition means are mounted on an XY table that can be moved in two horizontal directions by two DC motors, while the IC pellets are mounted. The lead frame is transferred to the bonding position on the workbench (frame feeder) at regular intervals. The bonding head and the television camera are fixed in position, and a work table (frame feeder) for transferring the lead frame is mounted on the XY table.

In any case, a control device including a central processing unit such as a microcomputer uses reference pattern data of the electrode pad as the shape and position of the electrode pad of the IC pellet to be wire-bonded in advance based on the design pattern. I remember it. Upon detection of the electrode pad, an image pattern obtained by capturing an image of a plurality of electrode pad portions of the IC pellet by a television camera and the data of the reference pattern are compared (image information in software or dedicated firmware). The position (coordinates) (or XY) of the TV camera in which both patterns are the best match (match) with each other.
Check the position (coordinates) of the IC pellet on the table. This is the so-called pattern matching method.

Next, in order to determine a reference point (for example, the center of gravity of a predetermined electrode pad) in the image pattern, the data of the imaged image pattern is binarized and the shape of the electrode pad is extracted. The coordinates of the center of gravity of the electrode pad are determined. The amount of deviation between the detected reference point (center of gravity point) of the electrode pad and the reference position (for example, the center of gravity position of the electrode pad) in the reference pattern data is calculated. By executing the position detection processing by such detection / calculation at two points of the IC pellet,
The position (coordinates) and angle of the pellet (angle of inclination of the XY plane with respect to the reference line) are detected, and the wire bonding work for the electrode pad is started based on the result of this calculation.

By the way, when comparing the reference pattern data with the imaged (detected) pattern image on the television monitor, it is customary to make the reference position of the reference pattern data coincide with the origin of the XY coordinates. On the other hand, when an image of the electrode pad is picked up by the TV camera, the detected electrode pad portion, particularly the image of the reference electrode pad, is the center of the image pickup range of the TV camera (center of the optical system)
Not necessarily located in.

In the prior art, a television camera or IC
As long as the pellet is roughly moved on the XY table and the IC pellet is within the field of view of the television camera, the image information of the electrode pad portion is taken in at that point, and the pattern matching recognition is executed, and then this image data is obtained. Therefore, the position of the reference point of the electrode pad, for example, the coordinates of the center of gravity is calculated as the amount of deviation of the XY coordinates, which is the reference position of the reference pattern data, from the origin.

[0008]

However, as a result of increasing the magnification in order to image a minute electrode pad, the depth of focus becomes shallow and the peripheral portion of the detection range becomes out of focus. In addition, since there is some optical system aberration in the TV camera, there are phenomena such as various image distortions such as image curvature, which are off the optical axis (center of the inspection range) of the TV camera. The image data of 1 contains a larger error than the image data in the vicinity of the optical axis. If the calculation for detecting the position of the image pattern, for example, the coordinates of the center of gravity of the electrode pad is executed based on the image data including such an error, the data of the position of the electrode pad also becomes incorrect.

Particularly, since the number of electrodes has been increasing with the high integration of ICs recently, the size of each electrode pad is
When the size is reduced from 100 μm square to 70 μm square, and the distance between adjacent electrode pads is also shortened, the wire bonding position with respect to the upper surface of the electrode pad is displaced due to the deviation of the position data of the electrode pad. However, there is a problem that accurate wire bonding cannot be performed, for example, the ball portion of the above-mentioned sticks out to another circuit pattern surface on the upper surface of the IC pellet, or in the worst case, it straddles two adjacent electrode pads.

Such a problem is caused not only by detecting the electrode pad position in the wire bonding work but also by detecting the position of the IC pellet when picking up a minute IC pellet from the XY table in the die bonding work for the lead frame. It also happened when. The present invention aims to solve the technical problem in detecting the position of such a minute electronic component.

[0011]

In order to achieve this object, the present invention reads image data of a work such as an electronic component by an optical image pickup means such as a television camera in an image recognition means, and detects the detected image data in advance. In the position detecting device for electronic parts, which is configured to detect the reference position of the work as compared with the stored reference position data, the optical imaging means or the work intersects the optical axis of the optical system of the optical imaging means. By relatively moving on a plane, image data is taken in, coordinate detection for rough positioning of the reference position on the work is executed, and the optical image pickup means or the work is moved again again to determine the reference on the work. A control means is provided to control the position so that the position is near the optical axis.

[0012]

[Embodiments] Next, embodiments embodying the present invention will be described. Reference numeral 1 in FIGS. 1 and 2 indicates an automatic wire bonding apparatus, in which a frame loader 4 for taking out the lead frames 3 from the magazine one by one is arranged on one side of the workbench 2, and the lead frames 3 are fed at an appropriate pitch. A storage unit 6 for storing the lead frame 3 that has undergone wire bonding is arranged on the other side of the frame feed table 5 which is moved to the wire bonding position. Reference numeral 7 is the XY plane (horizontal plane) via the screw shaft by the driving force of the X-direction drive motor 8 and the Y-direction drive motor 9 (both are DC motors).
A bonding head 10 and a television camera 11 as an image pickup means are mounted adjacent to each other on the XY table 7, which is movable along the XY table.

Although not shown, the bonding head 10 includes a capillary tool for inserting a metal thin wire such as a gold wire, a clamper for holding the metal thin wire, a torch for forming a molten metal ball portion at the lower end of the metal thin wire, and the like. And a drive mechanism for these parts. Reference numeral 12 is an image captured by the television camera 11 or an IC registered (stored)
The monitor television displays an image of the reference pattern 32 of the electrode pad of the pellet 31.

The operation of the entire automatic wire bonding apparatus 1 is controlled by an electronic control unit 13 such as a microcomputer. FIG. 3 is a functional block diagram of the control device 13,
DC driving XY table 7 and bonding head 10
Table central processing unit (CPU) 1 for motor control
5 and a central processing unit (CPU) 16 for image recognition means for operating the TV camera 11 and the monitor TV 12, exchanges various control signals and data signals with the main central processing unit (MCPU) 14. A table drive circuit 17 for driving the XY table and a bonding drive circuit 18 for operating the bonding head 10 are operated by a command control signal from the table central processing unit 15.

In the main central processing unit 14 and the central processing unit 16 for image recognition means, read-only memories (ROM) 19 and 20 in which control programs and arithmetic programs to be executed are stored and various data can be read and written. A memory (RAM) 21 and a screen memory 22 are connected. The main central processing unit 14 is connected to an interface 23 for receiving input signals from the input buttons and operation switches on the operation panel 28 of the workbench 2 and for inputting data, and the interface 23 is of a type to be wire-bonded described later. Of the IC pellet reference pattern 32 (electrode pads on the data are designated as P0, P
1, P2, P3) are recorded based on a design drawing, and data can be input from a record carrier such as a cassette and stored in the readable / writable memory (RAM) 21. In response to a command signal from the main central processing unit 14, the drive circuit 24 of the frame loader 4, the frame drive circuit 25 of the frame feed table 5, and the drive circuit 26 of the storage section 6 are operated. Reference numeral 27 is an interface of a control sensor at each control location (for example, detection of a predetermined feed pitch of the lead frame on the frame feed table 5).

Next, in the wire bonding work for the electrode pads E0, E1, E2, E3, ... Of the IC pellet 31 on the lead frame 3, the electrode pads E0,
The position detection operation control of E1, E2, E3 ,.
This will be described with reference to the subroutine flowchart of. Prior to the position detection of the electrode pads E0, E1, E2, E3, ..., The position (X where the IC pellet 31 is die-bonded to the island 3b of the lead frame 3
It is assumed that the Y coordinate) and the tilt (the tilt angle θ with respect to the X axis of the reference line) are detected, and the data of the position and the tilt are stored.

Following the start of the subroutine, initialization is executed (step 401). Here, electrode pads P0, P1, P for detecting the shape (dimension) in plan view and the position of the type of IC pellet to be wire-bonded are detected.
Since the data of the reference patterns 32 of P2 and P3 are input in advance by the operator, the data, particularly the reference position data of the electrode pad P0 serving as a reference and the coordinates (0,0) of the optical axis of the television camera 11 with respect to the XY table 7 are input. ) Etc. are read out and stored.

The coordinates of the reference electrode pad P0 are set to be the origin O (0,0) (see FIG. 5).
(See (a)). In the following, reference numeral 35 indicates the screen of the monitor television 12. In step 402, the XY table 7 is moved so as to image the upper left corner of the IC pellet 31 set at a predetermined position on the frame feed table 5, and step 403
With the TV camera 11, the electrode pads E0, E1, E2
The E3 ... portion is imaged, and the image data 34 is captured (see FIG. 5B). In this case, the electrode pads E0, E
The portions 1, E2, E3, ... Do not have to be located in the center of the inspection range 33 (field of view) by the TV camera 11,
It may be located at one corner of the inspection range 33. In step 404, a pattern matching process is performed to compare (superimpose) the data of the reference pattern 32 and the image data 34 to determine whether the patterns match. When the patterns match, in step 405, the coordinates of the electrode pad E0 corresponding to the reference electrode pad P0 are calculated to detect the rough position. Next, the coordinates of this rough position and the origin of the inspection range 33 by the TV camera 11, that is, the amount of deviation (ΔX1, ΔY1) from the coordinates (origin) O of the optical axis of the TV camera 11 are calculated (step 406, FIG. 5).
(See (c)), it is determined whether or not the amount of deviation is within a preset allowable range (step 407). Step 4
When it is determined that the value is out of the allowable range in 07 (when it is no), only the deviation amount (ΔX1, ΔY1) is used for the XY table 7.
After moving (step 408), the TV camera 11
Then, the electrode pads E0, E1, E2, E3, ...
The part is imaged and the image data 34 is captured (step 409, see FIG. 5D). As described above, at a position distant from the optical axis (origin) O of the television camera 11, the captured image is distorted due to the distortion of the optical system of the camera.
Since the position data of the image includes an error, the deviation amount itself also has an error. Therefore, step 4
08, the XY table 7 by the shift amount (ΔX1, ΔY1)
Even if is moved, the position of the reference electrode pad E0 does not always coincide with the origin, and generally there is still a minute shift amount.

Then, returning to step 406,
A deviation amount (ΔX2, ΔY2) of the position of the electrode pad E0 with respect to the coordinates (origin) of the optical axis of the television camera 11 is calculated (see FIG. 5E), and the deviation amount (ΔX2, ΔY2) falls within the allowable range. It is judged whether or not there is (step 407),
The flow from step 406 to step 409 is repeated until it is within the allowable range. This allowable range is set so as to be within an operation error range when wire bonding to the electrode pad. When it is determined in step 407 that the value is within the allowable range (yes), the reference electrode pad E0 is set.
The precise position detection for detecting the position of is performed and the position is stored. (Steps 410 and 411).

In this way, if the position of the object to be inspected is adjusted so as to be located in the vicinity of the optical axis of the optical system of the optical image pickup means in the image recognition means, the influence of the distortion of the optical system is very small. Therefore, the data of the detected position can be obtained accurately and accurately. In the case of detecting the position of the electrode pad, if the above-described position detecting operation is executed for two electrode pads located on the diagonal line of the IC pellet to be inspected, the positions of the remaining electrode pads are This can be easily known by performing a calculation in comparison with the design data of the pattern of the electrode pad, and the electrode pad on the IC pellet 31 and the lead portion 3a in the lead frame 3 can be gold-plated in the next step, wire bonding work. It suffices to connect with a thin metal wire 36 such as a wire (see FIG. 6).

The position detecting means of the present invention is a workpiece I.
Needless to say, the present invention can be applied to the operation of picking up a C pellet by setting the diagonal position of the rectangular IC pellet in plan view as a reference position and detecting the reference position.

[0022]

As described above, according to the present invention, the work such as the optical image pickup means or the electronic component is
The image recognition means performs relative coordinate movement on a plane that intersects the optical axis of the optical system of the optical image pickup means such as a television camera to capture image data and perform rough position detection for rough positioning of the reference position on the work. After that, the optical image pickup means or the work is controlled to be relatively moved again so that the reference position in the work comes close to the optical axis, so that the optical distortion is close to the optical axis of the optical system. The position of the reference position of the work is finally detected, and the influence of optical distortion in the optical image pickup means on the data of the position detection result of the reference position of the work can be minimized.

As described above, the reference position of the work can be detected with high accuracy by performing the position detection work a plurality of times, and as a result, the error included in the subsequent work can be reduced and the work with high accuracy can be performed.

[Brief description of drawings]

FIG. 1 is a plan view of an automatic wire bonding apparatus.

FIG. 2 is a front view of an automatic wire bonding device.

FIG. 3 is a functional block diagram of a control device.

FIG. 4 is a flowchart of a position detection subroutine.

5A to 5E are explanatory views of position detection on a monitor TV screen.

FIG. 6 is a diagram showing a result of wire bonding on a lead frame.

[Explanation of symbols]

 1 Automatic Wire Bonding Device 2 Working Table 3 Lead Frame 3a Lead Section 4 Frame Loader 5 Frame Feeding Table 6 Storage Section 7 XY Table 10 Bonding Head 11 TV Camera 12 Monitor Television 13 Controller 14 Main Central Processing Unit 15 Table Central Processing Unit 16 Central processing unit for image recognition 17 Table drive circuit 18 Bonding drive circuit 31 IC pellet 32 Reference pattern 33 Inspection range 34 Image data 35 Monitor TV screen

Claims (1)

Claims: 1. Image data of a work such as an electronic component is read by an optical imaging means such as a television camera in an image recognition means, and the detected image data is compared with reference position data stored in advance. Then, in the position detecting device of the electronic component configured to detect the reference position of the work, the optical imaging means or the work is relatively moved on a plane intersecting the optical axis of the optical system of the optical imaging means. , Image data is taken in, coordinate detection for rough positioning of the reference position on the work is executed, and the optical imaging means or the work is
A position detecting device for an electronic component by an image recognizing means, which is provided with a control means for controlling the reference position of the work so as to come close to the optical axis by relatively moving again.