JP2977954B2 - Wire bonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method applied to a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art A wire bonding apparatus includes an image pickup means for picking up an image of a lead of a lead frame and a pad of a semiconductor pellet, an image processing means for receiving and recognizing an image signal picked up by the image pickup means, and a recognition result of the image processing means. Control means for causing the bonding head to perform a wire bonding operation between the lead of the lead frame and the pad of the pellet based on the above.

Here, the image processing means sets (1) reference bonding coordinates on the leads of a reference lead frame as a representative of the same type at the teaching stage,
(2) In the production stage of the same product type, the amount of misalignment of the general lead frame with respect to the lead of the reference lead frame is detected.

Then, the control means sets the actual bonding coordinates on the lead of the general lead frame to the reference bonding coordinate set for the reference lead frame based on the positional deviation amount of the lead of the general lead frame detected by the image processing means. The bonding operation is performed by a bonding head based on the actual bonding coordinates.

However, in the prior art, the image processing means detects the positional shift amount of the general lead frame, as shown in FIG. 4 or FIG.
Is fixed in a direction of 0 degrees (see FIG. 4) or a direction of 90 degrees (see FIG. 5) with respect to the screen regardless of the inclination of the lead 2.

[0006]

However, in the prior art, as shown in FIG. 6 or 7, the lead 2 of the general lead frame is replaced with the lead 2A of the reference lead frame at the teaching stage.
, It may not be possible to detect within the initial range of the detection visual field 1. In this case, the image processing means gradually expands the range of the detection visual field 1 along the detection direction 1A and goes to search for the lead 2. For this reason,
The detection time becomes longer. Also, depending on the degree of bending,
Even if the range of the detection field of view 1 is increased, detection may not be possible.

It is conceivable to widen the range of the detection field of view 1 in advance. However, when the number of leads is large and the adjacent leads are close to each other, the adjacent leads are put together in the detection field of view. It may enter and is not appropriate because it causes false detection.

In the prior art, the coordinates on the lead detected by the image processing means within the detection visual field are the actual bonding coordinates. Therefore, if the leading end of the lead 2 is detected when the lead 2 is bent as shown in FIG.
The tip of the lead 2 becomes the actual bonding coordinates.
However, if the leading end of the lead 2 does not have a sufficient width for bonding, a bonding failure occurs.

An object of the present invention is to enable quick and accurate detection of a lead even if the lead is bent without unnecessarily expanding the detection range of the image processing means.

[0010]

According to the present invention, there is provided an image pickup means for picking up an image of a lead of a lead frame, and an image signal picked up by the image pickup means for recognizing the image signal. Image processing means for setting the reference bonding coordinates of the general lead frame and detecting the amount of positional deviation that the lead makes with respect to the lead of the standard lead frame; and the positional deviation of the general lead frame lead detected by the image processing means. Based on the amount, the actual bonding coordinates on the lead of the general lead frame,
In the wire bonding method, the image processing means is set by correcting the reference bonding coordinates set for the reference lead frame and using the control means for performing the bonding operation by the bonding head based on the actual bonding coordinates. When the reference bonding coordinates for the reference lead frame are set, the inclination of the lead is recognized, and when the amount of displacement is detected for the general lead frame, the detection visual field is set to a direction substantially perpendicular to the inclination direction of the lead of the reference lead frame. Is set to be detected.

According to a second aspect of the present invention, an image of a lead of a lead frame is taken using an image pickup means, and an image signal of the taken image is processed to obtain an ideal pattern of the lead.
A deviation amount from a reference lead position, which is a normal lead position obtained in advance, is detected based on the deviation amount, and actual bonding coordinates on the lead are obtained from the deviation amount and a predetermined reference bonding coordinate. in the wire bonding method to move the bonding head on the basis of the bonding coordinate perform bonding, when image processing of the image signal, the deviation amount
Only one field of view for each lead to detect
And the detection field of view is set in a direction substantially orthogonal to the inclination direction of the reference lead.

[0012]

The bending of the lead occurs in such a direction as to rotate around the root of the lead with respect to the lead frame.
Therefore, the bending direction of the lead of the general lead frame is
The direction substantially coincides with a direction substantially orthogonal to the inclination direction of the lead of the reference lead frame. At this time, in the present invention, the detection visual field of the image processing means is set in a direction substantially perpendicular to the inclination direction of the lead of the reference lead frame, and as a result, the detection visual field is in the bending direction of the lead of the general lead frame. As a result, the leads can be detected quickly and accurately without unnecessarily expanding the detection range of the image processing means.

[0013]

FIG. 1 is a schematic view showing an example of a wire bonding apparatus used in the embodiment of the present invention, FIG. 2 is a schematic view showing the principle of setting reference bonding coordinates in a reference lead frame, and FIG. FIG. 3 is a schematic diagram showing the principle of detecting the amount of positional deviation of FIG.

The wire bonding apparatus 11 includes a base 12
It has. The base 12 has an X moving motor 13 and a Y
An XY table 15 that is moved in the X and Y directions on a plane by a moving motor 14 and a feeder 17 that conveys a lead frame 16 are arranged to face each other. XY above
The table 15 is provided with a bonding head 18.

The bonding head 18 has a capillary 19 at the tip and supports a bonding arm 21 which is rotated by a Z movement motor 20.
A support 22 is provided. The support 22 has a wire spool 2 for supplying a wire to the capillary 19.
3 and an imaging device 24 for imaging the lead frame 16 conveyed by the feeding device 17 are attached.

An image processing device 25 and a control device 26 are sequentially and electrically connected to the imaging device 24. A memory 27 is connected to the image processing device 25.

The imaging device 24 comprises an ITV camera,
The leads 30 of the lead frame 16 and the pads (not shown) of the semiconductor pellet are imaged. Further, the image processing device 25
Captures and recognizes an image signal captured by the imaging device 24. Further, the control device 26 controls the motors 13, 1, 1
4 and 20 are driven to perform a wire bonding operation between the lead 30 of the lead frame 16 and the pad of the pellet.

Here, the image processing device 25 sets (1) the reference bonding coordinates 31A on the leads 30A for the reference lead frame 16A as a representative between the same types at the teaching stage, and (2) At the production stage of the product type, the lead 3 of the general lead frame 16B is
OB detects the amount of positional deviation (△ X, △ Y) that the reference lead frame 16A makes with respect to the lead 30A.

Then, the control device 26 controls the image processing device 2
5 lead 30B of general lead frame 16B detected
Is set by correcting the actual bonding coordinates 31B on the leads 30B of the general lead frame 16B with respect to the reference bonding coordinates 31A set for the reference lead frame 16A on the basis of the positional deviation amounts (ΔX, ΔY). Then, the bonding operation by the bonding head 18 described above is performed based on the actual bonding coordinates 31B.

However, in this embodiment, the reference lead frame 16A of the image processing device 25 in the above (1) is used.
The reference bonding coordinates 31A on the lead 30A are set as follows.

The lead 30A is designated by the operator (see FIG. 2A).

In the detection visual field 32 of the image processing device 25,
The edge of the lead 30A is detected to determine the lead width, and the center coordinate point A of the lead width is calculated (see FIG. 2B).

At this time, the lead 30A is detected in both the X direction and the Y direction, and the lead widths measured by this detection are compared, the detection direction in which the smaller width is detected is selected, and the center coordinates are obtained.

In the detection direction selected above, a coordinate point B at the center of the lead width of the lead 30A is calculated at a position away from the coordinate point A by a distance M in the Y direction (see FIG. 2B).

The inclination θ of the lead 30A is determined from the coordinate points A and B. At this time, the inclination θ of the lead 30A is stored in the memory 27.

The detection field of view 32 of the image processing device 25 is set in the direction of inclination of the lead 30A, the down edge of the imaging output is searched, and the tip of the lead 30A is recognized. Detection field of view 32
If the leading end of the lead 30A cannot be detected in the initial range, the detection range is gradually widened in the inclination direction of the lead 30A. The point at which the straight line connecting the coordinate points A and B intersects the tip of the lead 30A becomes the coordinate point C of the tip of the lead 30A (see FIG. 2C).

With the coordinate point C at the tip of the lead 30A as the origin, on the lead 30A, in the inclination direction of the lead 30A,
A bonding coordinate D is set at a position at a specified distance L (see FIG. 2D).

Here, the distance L has a sufficient lead width for bonding wires on the leads 30A, and when forming a wire loop, adjacent wire loops do not come into contact with each other. Is the distance from the tip of the lead set to.

Further, in this embodiment, the detection of the amount of displacement (.DELTA.X, .DELTA.Y) of the lead 30B of the 16B of the general lead frame in the above (2) of the image processing device 25 is performed as follows. .

That is, the image processing device 25 recognizes the inclination θ of the lead 30A and stores it in the memory 27 when setting the reference bonding coordinates 31A for the reference lead frame 16A. Therefore, the image processing device 25 changes the detection visual field 32 to the lead 30A of the reference lead frame 16A when detecting the positional deviation amount (△ X, △ Y) of the lead 30B with respect to the general lead frame 16B.
Is set in a direction substantially perpendicular to the inclination direction of the detection (see FIG. 3A).

Next, the operation of the above embodiment will be described.

Lead 30B of general lead frame 16B
Is generated in such a direction as to rotate around the base of the lead 30B with respect to the lead frame 16B.
Therefore, the bending direction of the lead 30B of the general lead frame 16B is the same as that of the lead 30A of the reference lead frame 16A.
Is substantially coincident with a direction substantially orthogonal to the inclination direction of
At this time, in the above embodiment, the detection visual field 32 of the image processing device 25 is changed to the lead 30 of the reference lead frame 16A.
A is set in a direction substantially orthogonal to the inclination direction of A, and as a result, the detection visual field 32 substantially matches the bending direction of the lead 30B of the general lead frame 16B, and the detection range of the image processing device 25 is unnecessarily expanded. Thus, the lead 30B can be detected quickly and accurately.

Therefore, even if the lead 30B is bent,
The probability of deviating from the detection visual field 32 is reduced, and the lead 30B
As long as the curve is not extremely large, it does not deviate from the detection visual field 32, and the detection time can be shortened.

Further, when the lead 30B is bent, the deviation amount of the actual bonding coordinates 31B from the corresponding coordinates 31A 'of the reference bonding coordinates 31A can be reduced (see FIG. 3B). In FIG. 3 (B),
Reference numeral 31C denotes a detection position when the direction of the detection visual field 32 is set to a direction of 90 degrees with respect to the screen, and the deviation amount of the reference bonding coordinate 31A from the equivalent coordinate 31A 'is large.

In the above embodiment, the detection visual field 32
When setting the lead 3 of the reference lead frame 16A
Although the inclination is detected at 0A and the direction is set so as to be substantially orthogonal to the detected inclination direction, the inclination direction of the lead may be obtained based on the ideal pattern of the lead frame.

[0036]

As described above, according to the present invention, even when the lead is bent, the lead can be detected quickly and accurately without unnecessarily expanding the detection range of the image processing means.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a wire bonding apparatus used for carrying out the present invention.

FIG. 2 is a schematic diagram illustrating a principle of setting reference bonding coordinates in a reference lead frame.

FIG. 3 is a schematic diagram showing a principle of detecting a lead displacement amount in a general lead frame.

FIG. 4 is a schematic diagram showing a state in which the direction of a detection visual field is set to a direction of 0 degrees.

FIG. 5 is a schematic diagram showing a state in which the direction of a detection visual field is set to a direction of 90 degrees.

FIG. 6 is a schematic diagram showing a bent state of a lead when the detection direction is 0 degree.

FIG. 7 is a schematic diagram showing a bent state of a lead when the detection direction is 90 degrees.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Wire bonding apparatus 16A Reference lead frame 16B General lead frame 18 Bonding head 24 Imaging device 25 Image processing device 26 Control device 30A, 30B Lead 31A Reference bonding coordinate 31B Actual bonding coordinate 32 Detection visual field

Claims (2)

(57) [Claims] 1. An image pickup means for picking up an image of a lead of a lead frame, an image signal picked up by the image pickup means being taken in and recognized, a reference bonding coordinate on the lead is set for a reference lead frame, and Image processing means for detecting the amount of displacement of the lead with respect to the lead of the reference lead frame; and actual bonding on the lead of the general lead frame based on the displacement of the lead of the general lead frame detected by the image processing means. In a wire bonding method, the coordinates are set by correcting with respect to the reference bonding coordinates set for the reference lead frame, and based on the actual bonding coordinates, control means for performing a bonding operation by a bonding head is used. The image processing means includes a reference read frame. When setting the reference bonding coordinates for the system, the inclination of the lead is recognized, and when the amount of displacement of the general lead frame is detected, the detection visual field is set in a direction substantially orthogonal to the inclination direction of the lead of the reference lead frame. A wire bonding method characterized by detecting. 2. A lead of a lead frame is picked up by an image pickup means, and an image signal of the picked-up image is processed to obtain a correct lead obtained in advance based on an ideal pattern of the lead.
The amount of deviation from the reference lead position, which is the standard lead position, is detected, and the actual bonding coordinates on the lead are obtained from the amount of deviation and the preset reference bonding coordinates, and bonding is performed based on the obtained actual bonding coordinates. In the wire bonding method in which the head is moved to perform the bonding, when the image signal is subjected to the image processing, one of the ones for which a shift amount is to be detected is used.
A single detection field of view is set for each of the leads, and the detection field of view is set in a direction substantially perpendicular to the inclination direction of the reference lead.