JPH0897241A - Lead bonding position locating order determining method and its device - Google Patents

Abstract

PURPOSE: To improve the working efficiency by notably cutting down the shifting time and distance of a table etc., for shifting an image pick-up means during lead locating and to develop the excellent general purpose capacity by determining the lead locating order by the real time processing. CONSTITUTION: An image pick-up means 3 is successively shifted to respective target positions previously stored corresponding to respective bonding positions 2x of plural numbers of leads so that the displacement from the target positions to actual bonding positions may be successively located through said image pick-up means 3 so as to successively correct corresponding to the located displacement thereby locating the target positions at the shortest straight line distance to the bonding positions 2x of the leads 2a immediately after locating the displacement not yet located assuming the located target positions to be the next shifting positions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead bonding position detection order determination method and device applicable to a wire bonder or a wire bonding inspection device, and more particularly, to a lead target position for a plurality of leads. The present invention relates to a technique for determining the order in which the imaging means is efficiently transferred to perform the locate.

[0002]

2. Description of the Related Art In recent years, along with the increase in the number of external leads and the fine pitch of external leads of semiconductor devices, there has been a demand for refinement of wire bonding methods for semiconductor chips to be bonded to islands of a lead frame during manufacturing. ing. Along with this, the bonding area of each lead of the lead frame becomes narrower, and further, the narrowing of the lead frame causes deformation in the cutting process, resulting in variation in the bonding position of the lead tip. .

In order to deal with such a situation, as a pre-process of performing wire bonding to the bonding position of each lead by a wire bonder, the bonding target position stored in advance is corrected and corrected. The actual situation is that the lead locate for performing the various position setting is performed by using the image processing.

This lead locate moves an image pickup means such as an ITV camera to an area corresponding to the bonding target position, and at this time, detects a displacement amount between the actual lead bonding position and the target position captured by the image pickup means. To do. Then, the target position is corrected by the detected displacement amount, and the corrected position is stored in the storage unit of the wire bonder as a new target position, and such an operation is predetermined for each lead. It goes in the order of.

On the other hand, FIG. 7 shows an extreme example of the order in which wire bonding is performed on each of the leads, for the reason of, for example, avoiding interference between the wiring and the capillary immediately after wiring. For the bonding position at the tip of each lead L, reference signs X1, X
In some cases, the process may be performed in the order of 2, X3, X4, and X5.

[0006]

Now, considering the correlation between the order of performing the wire bonding and the order of performing the lead locate, if the wire bonding is performed according to the order of performing the lead locate. The wire bonding can be advanced along the same path as the moving path of the image pickup means during the lead locate. In other words, wire bonding can be performed simply by basically reproducing the moving path of the image pickup means.

For this reason, according to the extreme example described above, the conventional lead locate is performed according to the order of wire bonding X1 to X5 shown in FIG. Therefore, due to this, the efficiency of the lead locate work was deteriorated.

Particularly, in such an order, it is necessary to change the direction frequently when the image pickup means is transferred, which complicates the control, and the movement of the XY table or the like for moving the image pickup means. This caused a problem that the time and the moving distance became long.

Further, in the above-described conventional lead locate method, since the position at which the image pickup means is moved is determined in advance, for example, in order to perform lead locate for a lead frame having different lead arrangement pitches. ,
Each target position stored in the storage means of the wire bonder must be changed. Therefore, such a method cannot be immediately applied to different types of lead frames, and there is also a problem of poor versatility.

The present invention has been devised under the above circumstances, and shortens the moving time and the moving distance of a table or the like for moving the image pickup means when performing the read locate. The task is to improve work efficiency, determine the order of lead locate by real-time processing, and have excellent versatility.

[0011]

In order to solve the above problems, the present invention takes the following technical means.

That is, in the invention described in claim 1 of the present application, the image pickup means is sequentially transferred to the respective target positions stored in advance corresponding to the respective bonding positions of the plurality of leads, and the target is passed through the image pickup means. A method of sequentially detecting the displacement amount between the position and the actual bonding position, and sequentially correcting the target position according to the detected displacement amount. The present invention is characterized in that a target position whose straight line distance is the shortest with respect to the bonding position and the displacement amount is not detected yet is obtained, and the obtained target position is set as the next transfer position of the image pickup means. .

Further, the invention described in claim 2 of the present application is
Based on the image data from the storage unit that stores each target position corresponding to each bonding position of the plurality of leads, the image capturing unit that captures the peripheral image of the actual bonding position at each target position, and the image data from the image capturing unit. Image recognition means for detecting the amount of displacement between the target position and the actual bonding position, and correction means for correcting the target position stored in the storage means according to the amount of displacement detected by the image recognition means. A device provided with a linear distance that is the shortest with respect to the bonding position of the lead immediately after the detection of the displacement amount based on signals from the image recognition unit and the storage unit, and the displacement amount. It is characterized by including a detection order determining means for determining a target position for which detection of is not executed as a target position for executing detection of the subsequent displacement amount. .

[0014]

According to the invention described in claim 1, the order of detecting and correcting the displacement amount for a plurality of leads (lead locate) is, for example, displacement relative to the first target position. Immediately after the amount is detected and corrected, the second target position is determined on the basis of this position.

More specifically, the second target position having the shortest linear distance from the first target position (lead bonding position) and the displacement amount detection not yet performed is obtained,
The image pickup means is transferred to this target position, and the displacement amount is detected and corrected. Then, by repeating the same operation as this, the n + 1-th target position is sequentially determined with the n-th target position immediately after the detection of the displacement amount as a reference (where n is An integer greater than or equal to 1).

In other words, instead of performing the lead locate according to a predetermined order as in the conventional case, the next lead locate should be performed immediately after the lead locate is performed with reference to the lead bonding position. The lead bonding position will be determined.

Accordingly, even if the lead frame to be lead-located is changed to a different lead frame due to the arrangement pitch of each lead being different, the order of performing the lead-locating is more suitable for the real-time processing as described above. Therefore, excellent versatility can be obtained.

In addition, as compared with the conventional example in which the lead locate is performed in the same order as the wire bonding order, the moving path of the image pickup means is not wasted, and the moving distance and the moving time are greatly shortened. It As a result, work efficiency or workability is improved.

On the other hand, according to the invention described in claim 2, the above-described detection order determining method is appropriately implemented. That is, when the signal from the image recognition means indicates that the displacement amount detection is executed based on the image data from the image pickup means, the detection order is based on the lead bonding position targeted for the displacement amount detection at that time. The deciding unit decides a target position to be the next target of displacement amount detection from the respective target positions stored in the storage unit. Therefore, also in this case, the adverse effect of performing the lead locate according to the predetermined wire bonding sequence can be avoided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
A specific description will be given with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of a main part of a lead bonding position detection order determination device and its control system according to an embodiment of the present invention.

As shown in FIG. 1, the schematic structure of the detection order determining apparatus 1 according to this embodiment is mainly for capturing a peripheral image of each lead portion 2a of the lead frame 2.
Imaging means 3 such as a TV camera, arm 4a and support 4
and a moving table 4 which supports the image pickup means 3 via b. The image pickup means 3 has a coaxial illumination function (a lens with a coaxial illumination), and a signal indicating image data from the image pickup means 3 is generated by the operation of an A / D converter (not shown) or the like. It is converted to a signal required for control. The moving table 4 is held on guide tables 5 and 6 for guiding the movement in the X direction and the Y direction which are orthogonal to each other.

On the other hand, the control system 10 of the detection order determining device 1 stores the target position corresponding to the bonding position of each lead 2a of the lead frame 2 in the storage means 7.
And an image recognition means 8 for detecting the displacement amount between the actual bonding position of each lead portion 2a and each target position based on the image data from the image pickup means 3, and this image recognition means 8. The correction means 9 for correcting the target position stored in the storage means 7 according to the displacement amount is provided as a basic constituent element.

Further, the control system 10 is provided with a detection order determination means 11 for determining the order of performing the displacement amount detection based on signals from the image recognition means 8 and the storage means 7. Specifically, this detection order determination means 1
Reference numeral 1 indicates the bonding position immediately after the end of the lead locate (that is, the detection of the displacement amount and the correction of the target position thereof) based on the signal from the image recognition means 8 and the detected bonding position. Then, the target position corresponding to the bonding position where the linear distance is the shortest and the lead locate has not been executed is obtained from the target positions stored in the storage means 7.

The position data corresponding to the obtained target position is transferred from the detection order determination means 11 to the transfer control means 1
2 is sent. By moving the moving table 4 in the X-Y directions according to the position data, the image pickup means 3 moves to the bonding position (target position) where the read locate should be performed next.

If necessary, the lead frame 2
It is also possible to separately provide an illuminating means (not shown) below the image pickup means 3 so as to sandwich the above, and to illuminate the lead frame 2 from below with this illuminating means.

FIG. 2 shows each component of the detection order determination device 1 as an electrically connected state of each device. That is, the apparatus 1 is configured such that the moving table 4 and the lead frame transporting apparatus 13 arranged near the moving table 4 are provided.
A camera 3 as the image pickup means, and a recognition device 14 connected to the camera 3 and having the image recognition means 8;
A display 15 connected to the recognition device 14 is provided.

Further, a coordinate calculation unit 16 is connected to the recognition device 14, and the coordinate calculation unit 16 is also connected.
The storage means 7, the operation switch 17, and the XY driver 18 described above are connected to. Therefore, the coordinate calculation unit 14 can calculate the displacement amount and determine the detection order described above, for example. In addition, the XY driver 18 can control the transfer of the moving table 4.

Further, the storage means 7 shown in the figure includes a reference coordinate storage section 7a for storing the coordinates corresponding to the target position before correction and a corrected coordinate storage for storing the coordinates corresponding to the target position after correction. The unit 7b and a normal storage unit 7c that stores various other information necessary for control are built-in.

Now, the structure of the lead frame 2 and the structure of the semiconductor chip 20 die-bonded to the lead frame 2 will be described with reference to FIGS. 3 and 4.

As is apparent from FIG. 3, the lead frame 2 is provided with a large number of leads 2a having a narrow mutual pitch for each of the four side dam bars 21 that define the region to be resin-packaged. There is. And
An island 22 to which the semiconductor chip 20 is bonded is formed in the center of each of the leads 2a.
The island 22 is supported by the support frame 23.

When manufacturing a semiconductor device, as shown in FIG. 4, under the condition that the semiconductor chip 20 is bonded onto the island 22, the tip portions (pads) 2x of the leads 2a and the semiconductor chip 20 are bonded. The upper terminal pads 20x are connected by wire bonding W. In this case, the tip 2x of each lead 2a
In general, the mutual dimensions are varied due to the influence of the stress acting during the cutting process.

Next, the operation of the detection order determining apparatus 1 according to the above embodiment or the detection order determining method performed by using this apparatus 1 will be described with reference to the flowchart shown in FIG.

First, as a preliminary step, the tip end portion 2x of each lead 2a, which is determined in advance according to the type of the lead frame 2, that is, the target position corresponding to each bonding position is stored in the storage means 7 (reference coordinate storage portion 7a). Then, for example, based on the input signal from the operation switch 5 shown in FIG. 2, the coordinate calculation unit 16 causes the bonding position of a specific lead 2a among a large number of leads 2a (preferably indicated by a symbol Z in FIG. 5). Select the bonding position 2x) at the corner and start the lead locate.

In performing this read locate, first, in step S1 of the flowchart, the transfer control means 12 (XY driver 18) causes the storage means 7 to operate.
The image pickup means 3 is moved to the target position corresponding to the bonding position 2x of the selected lead on the basis of the data from.

After this, read locate is executed in step S2. That is, the image recognition means 8 detects the amount of displacement between the target position and the actual bonding position based on the image data from the image pickup means 3. Then, in step S3, a new target position is calculated by adding a correction corresponding to the displacement amount to the target position, and the new target position is stored (registered) in the storage means 7. In this case, in detecting the displacement amount based on the image data, the image data from the image pickup means 3 is binarized, and the displacement dimension of the both on the binarized image is measured by an existing method such as pattern matching. be able to. However, it goes without saying that the measurement may be performed based on a combination of a search method on an image and a geometrical method other than this, or a geometrical or arithmetical method using pixels.

A specific method for detecting the displacement amount is, for example, from the peripheral image of the bonding position 2x captured by the image pickup means 3, for example, the image pickup center position of the image pickup means (camera) 3 and the actual bonding. This is performed by detecting the amount of displacement from the position 2x, in other words, how much the imaging center of the camera 3 is displaced with respect to the actual bonding position 2x. Note that the correction of the displacement amount after this is performed by, for example, moving the moving table 4 until the positions of both of them match on the image, in addition to performing the dimension measurement processing on the image as described above. It can also be performed by detecting.

Then, until it is judged in step 4 that the lead locate for all the leads 2a is completed,
The following steps 5 to 6 are executed.

That is, in the step 5, the target position where the straight line distance from the bonding position 2x (the target position) immediately after the end of the lead locate is the shortest and the lead locate is not yet executed is the above. It is obtained from the target positions stored in the storage means 7. Then, the transfer control means 12 moves the image pickup means 3 to the obtained target position. Specifically, the XY driver 18 moves the moving table 4 based on a signal from the coordinate calculation unit 16 (detection order determining unit 11), thereby moving and stopping the image pickup unit 3.

Thereafter, in steps 6 and 7, the displacement amount between the obtained target position and the actual bonding position 2x is detected in the same manner as described above, and a new target position after the displacement amount correction is detected. It is stored in the storage means 7. Then, after that, step 5 is executed again to determine the target position for the next lead locate based on the bonding position 2x at this time.
Further, steps 6 and 7 are executed to calculate and store a new target position corresponding to the determined bonding position 2x.

As a result of the above operations being repeated, for example, when lead locate is started from the bonding position 2x of the lead shown by Z in FIG. 5, the bonding position adjacent to this is the next lead. Be subject to locate. In this way, by moving the bonding positions targeted for lead locate to the adjacent one by one, the lead locate can be executed along the paths indicated by arrows A, B, C, and D in FIG. Become.

In this case, taking the arrangement state of the leads and the bonding positions 2x shown in FIG. 5 as an example, the order of performing the wire bonding W is a request for avoiding interference between the wiring W immediately after wiring and the capillary. In order to comply with, it was done as follows. That is, with reference to the bonding position of each corner, for example, arrows A1, A2, B1, B2, C1, C2, D
Wire bonding was performed in the order of 1 and D2.

If the wire bonding is performed in the order in which the lead locate is performed, the wire bonding can be advanced along the same path as the moving path of the image pickup means 3, and the moving path of the image pickup means 3 is basically used. Conventionally, the order of performing read locate has been previously determined to be the order of A1, A2 to D1, D2, for the reason that it only needs to be reproduced.

For this reason, since the moving table 4 is frequently reversed in the moving direction to move the same portion a plurality of times, the moving distance and the moving dimension are inevitably long, and the work efficiency is improved. It was getting worse. Also, if the order of performing lead locate is determined in advance as described above, lead locate cannot be performed for different types of lead frames depending on the method.

However, as in the present invention, when the lead locate at one bonding position is completed,
By adopting the method of determining the shortest subsequent bonding position based on the bonding position, it becomes possible to efficiently perform lead locate in the order of A, B, C and D as described above. . Further, in this way, when the lead locate of one bonding position is completed, if the method of determining the bonding position for performing the next lead locate, it is possible to use different lead frames with different arrangement pitch of each lead. However, it becomes possible to appropriately proceed with the read locate by the same method.

After completing the lead locate, the bonding position 2x of each lead 2a is completed.
And the terminal pads 20x on the semiconductor chip 20 are wire-bonded. The order of this wire bonding is not particularly limited,
It may be performed in the same order as the above-mentioned conventional method. In this case, since the positioning of the capillary for performing the wire bonding is performed based on the corrected target position stored in the storage means 7, even if the lead bonding position varies, it is always accurate. It is possible to perform various wire bonding.

On the other hand, the position of each terminal pad 20x on the semiconductor chip 20 is detected, for example, as follows.

That is, referring to FIG. 4, on the surface of the semiconductor chip 20 bonded to the island 22 of the lead frame 2, two recognition marks 30, 30 are attached to the corners along the diagonal line. , The image pickup means 3
Thus, the respective coordinates of the two recognition marks 30, 30 are obtained, and the position error and the attitude error of the semiconductor chip 20 are calculated from the displacement amount between the obtained respective coordinates and the previously known ideal coordinates. Then, based on these errors, the actual position of each terminal pad 20x of the semiconductor chip 20 is calculated and stored. That is, the semiconductor chip 20 has extremely high rigidity as compared with the lead 2a. Therefore, since the terminal pads 20x are arranged on the surface of the semiconductor chip 20 without causing variations, an error due to bonding may occur. The actual position of each terminal pad 20x can be recognized only by detecting.

The wire bonder having the capillaries may be installed on the moving table 4 on which the image pickup means 3 is supported, or at any other place which is a hindrance to the application of the present invention. Does not occur.

By the way, in the above-mentioned embodiment, the present invention is applied to the pre-process for performing the bonding work by the wire bonder. In addition to this, for example, the inspection process by the wire-bonding inspection device for judging the quality of the wire bonding is performed. The present invention can be similarly applied to the previous step.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a main part of a lead bonding position detection order determination device and a control system therefor according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an electrical connection state of each component of the detection order determination device.

FIG. 3 is a main part plan view showing a lead frame which is a target of lead locate by the detection order determination device.

FIG. 4 is an enlarged plan view showing a main part of the lead frame.

FIG. 5 is an enlarged plan view of an essential part showing a state in which each bonding position of the lead frame and each bonding position of the semiconductor chip are connected by wire bonding.

FIG. 6 is a flow chart showing an operation of the detection order determination device and explaining a detection order determination method according to the present invention.

FIG. 7 is an enlarged plan view of an essential part for showing the conventional problems and for explaining the detection order for each lead of the lead frame.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection order determination device 2 Lead frame 2a Each lead 3 Imaging means (camera) 4 Moving table 7 Storage means 8 Image recognition means 9 Correction means 11 Detection order determination means 12 Transfer control means 14 Image recognition means (recognition device) 16 Coordinate operation Part (correction means, detection order determination means) 18 Transfer control means (XY driver)

Claims (2)

[Claims] 1. An image pickup means is sequentially transferred to each target position stored in advance corresponding to each bonding position of a plurality of leads, and the displacement amount between the target position and the actual bonding position is obtained through this image pickup means. It is a method of sequentially detecting and sequentially correcting the target position according to the detected displacement amount, and the linear distance is the shortest with respect to the lead bonding position immediately after the detection of the displacement amount is completed. A method for determining a lead bonding position detection order is characterized in that a target position for which the displacement amount has not been detected yet is obtained, and the obtained target position is used as the next transfer position of the imaging means. 2. A storage unit for storing each target position corresponding to each bonding position of a plurality of leads, an image pickup unit for picking up a peripheral image of an actual bonding position at each of the target positions, and an image pickup unit from this image pickup unit. Image recognition means for detecting the amount of displacement between the target position and the actual bonding position based on image data, and correction of the target position stored in the storage means according to the amount of displacement detected by the image recognition means. A device having a correction means for performing, based on a signal from the image recognition means and the storage means, the linear distance is the shortest with respect to the bonding position of the lead immediately after the detection of the displacement amount is finished. And a detection order determining means for determining a target position for which the displacement amount is not detected yet as a target position for executing the subsequent displacement amount detection. Wherein the detection order determination apparatus lead bonding position.