JP2000068319A - Wire bonding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire bonding apparatus for connecting an electrode and a lead in a semiconductor chip, which is controlled under the control of a microcomputer so that a movement path of a capillary forms a Bezier curve for obtaining high reproducibility. SOLUTION: An X-axis movement table 24 and a Y-axis movement table 24 are installed on a base 20 to move in a horizontal plane. A Z-axis drive mechanism 25, including a cam mechanism, is installed above the Y-axis table 24, and an arm 28 is extended from the Z-axis mechanism 25. A capillary 30, through which a wire 29 is passed, is provided at a tip end of the arm 28 to be slidably moved vertically by a Z-axis motor 32. A linear function and a Bezier function which determined the movement path of the capillary 30 are stored in a loop information storage 2 in a control microcomputer 1, and a loop controller 3 is operated so that the capillary 30 moves along the movement path which corresponds to a combination of a straight line and a Bezier curve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding apparatus and, more particularly, to a wire bonding apparatus for controlling the operation of a capillary from a first bonding point of an electrode of a chip to a second bonding point of a lead through which a wire is passed by a microcomputer. Belongs to the technical field of equipment.

[0002]

2. Description of the Related Art In a conventional wire bonding apparatus for connecting an electrode of a chip and a lead with a wire, a capillary is connected to a X-axis and a Y-axis in a horizontal plane from a first bonding point of the chip electrode to a second bonding point of the lead. An X-axis moving table and a Y-axis moving table that move in the axial direction, a Z-axis driving mechanism that swings up and down (in the Z-axis direction),
It has a servo drive control section for controlling these.
At the tip of the Z-axis drive mechanism, there is a capillary into which a wire is inserted, and the capillary moves along a locus combining a straight line and an approximate arc.

FIG. 8 is a block diagram showing an example of the configuration of a conventional wire bonding apparatus. 8, an X-axis moving table 22 having an X-axis motor 21 and a Y-axis moving table 2 having a Y-axis motor 23 are provided on a base 20.
4 are installed, and an X-axis motor 21 and a Y-axis motor 23
The table moves in the horizontal plane by the rotation of. A Z-axis driving mechanism 25 is installed on the Y-axis moving table 24, and the Z-axis driving mechanism 25 is
7 rotatably supported. An arm 28 extends from the Z-axis drive mechanism 25, and a capillary 30 through which a wire 29 is inserted is held at the tip of the arm 28. The Z-axis drive mechanism 25 has a Z-axis motor 32 for swinging the arm 28 up and down. The upper part of the capillary 30 is provided with a wire clamp 40 which is clamped when cutting the wire 29 from the second bonding point.

A bonding stage 33 for mounting a lead frame 51 on which a chip 50 to be bonded is mounted is provided on the base 20. The chip 50 has electrodes 52, and the electrodes 52 are formed by bonding.
And the lead 53 are connected by the wire 29. Next to the Z-axis driving mechanism 25 on the Y-axis moving table 24, a holder 34 is provided.
Are extended, and an ITV camera 35 is attached to the holder 34.
Has been fixed. The ITV camera 35 is movable within a horizontal plane with respect to the bonding portion, and captures an image of the bonding portion to read an image and convert it into an electric signal.

[0005] The image recognizing section 36 performs image recognition of the video signal read by the ITV camera 35 and outputs positioning information necessary for wire bonding to the control section 37. The control unit 37 controls the position of the capillary 30 based on the positioning information. The loop controller 38 included in the controller 37 includes a position in the horizontal plane on the X axis and the Y axis of the capillary 30 and a position on the Z axis when the capillary 30 moves from the first bonding point to the second bonding point. The parameters of the upper and lower positions are set in advance, and the loop controller 38 outputs a control signal for moving the capillary 30 along a predetermined trajectory according to the parameters.

The servo drive control unit 39 includes a loop control unit 38
By rotating the X-axis motor 21 and the Y-axis motor 23 according to the signal from the X-axis moving table 22, the X-axis moving table 22 and the Y-axis moving table 24 are moved in the horizontal plane. Further, the servo drive control section 39 drives the Z-axis motor 32 to swing the arm 28 up and down. Thus, the capillary 30 moves along a locus determined from the first bonding point to the second bonding point.

Next, the bonding operation of the conventional wire bonding apparatus will be described with reference to FIGS. FIG. 9 is a three-dimensional graph showing the movement trajectory of the capillary during the operation of the conventional wire bonding apparatus shown in FIG. According to FIG. 8, the chip 50 is mounted on the upper surface of the lead frame 51 on the bonding stage 33. Prior to performing wire bonding, the electrodes 52 and the leads 53 of the chip 50 are imaged by the ITV camera 35. This image is converted into an electric signal and
The image is recognized, the bonding position is detected, and the control unit 3
It is sent to 7. In the control unit 37, the position information and the control unit 3
Using the parameters of the movement trajectory of the capillary 30 preset in the loop control unit 38 included in 7, a control signal for moving the capillary 30 in a straight line when ascending and moving along an approximate arc trajectory when descending is generated. . With this control signal, the servo drive control unit 39 moves the capillary along a locus set from the first bonding point to the second bonding point.

When the capillary 30 moves from the first bonding point to the second bonding point, the wire 29 inserted into the capillary 30 spans the two points, and the electrode 52 of the chip 50 and the lead 53 are looped by the wire 29. And are connected. When the connection is completed, the capillary 30 moves up, moves to the first bonding point, and moves to the next bonding operation. While the capillary 30 is being raised, the wire clamp 40 on the upper part of the capillary 30 is closed and moved upward, whereby the wire 29 is cut, and then a ball is formed by sparking for the next bonding.

Next, the movement locus of the capillary 30 will be described with reference to FIG. According to FIG. 9, the capillary 30
Rises along a linear trajectory from R ₀ to R ₁ at the first bonding point, moves horizontally from R ₁ to R ₂ along a linear trajectory in a direction opposite to the direction of the second bonding point, and reaches a maximum from R _2. until R ₃ position elevated in a linear path, from R ₃ to R ₆ of the second bonding point via R _4, R ₅ descends locus of approximate arc. R _{0 at} the first bonding point
The step D on the Z-axis of R ₆ at the second bonding point corresponds to the height of the chip 50.

[0010]

However, the above prior art has the following problems. The first problem is that the capillary moves linearly in three directions until it reaches the highest position after rising from the first bonding point, and moves along an approximate arc locus from the highest position to the second bonding point. Since the trajectory of the capillary is as simple as a straight line and an approximate arc, the wire passing through the wire insertion hole of the capillary during the movement of the capillary is not smoothly performed, and it is difficult to form a good loop. It has become. Also, when the distance from the first bonding point to the second bonding point is increased due to the increase in the wire length of the bonding, a good loop cannot be formed. As a result, the reliability and accuracy of bonding are not improved.

In recent years, with the demand for higher density and higher precision of semiconductor chips, miniaturization, increase in the number of pins, and sharing of lead frames have progressed, and the distance from the first bonding point to the second bonding point has been increasing. . As a result, wire bonding has become longer, and it is difficult to cope with the operation of the capillary along a locus of only a straight line and an arc.

The second problem is that the capillary moves linearly in three directions from the first bonding point to reach the highest position, and moves from the highest position to the second bonding point along an approximate arc locus. As a result, the moving direction of the capillary is changed three times, and the servo mechanism for driving the capillary requires time for stabilization each time, and the time for wire bonding becomes longer. As a result, the bonding speed does not increase.

A third problem is that since the speed of the capillary when moving from the first bonding point to the second bonding point is not controlled, when the bonding operation is repeated, the time between the first bonding point and the second bonding point is reduced. The reproducibility of the moving time and the moving trajectory is poor, so that the shape of the loop varies and the reproducibility of the loop formation deteriorates. As a result, the reliability and accuracy of bonding are not improved.

A fourth problem is that since the speed of the capillary is not controlled until it rises from the second bonding point and returns to the first bonding point, the capillary rises to form a ball for the next bonding. When making the wire to exit the tip of the capillary, if the speed of the capillary varies, the length of the wire coming out of the capillary tip changes, which causes variations in the size of the ball and the reproducibility of ball formation. become worse. As a result, the reliability of bonding is not improved.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to control the movement of a X-axis moving table and a Y-axis moving table in a horizontal plane and the vertical movement of a Z-axis driving mechanism in a wire bonding apparatus by a microcomputer. Control, the capillary moves along the optimal trajectory from the first bonding point to the second bonding point, a good loop is formed, and the reliability and accuracy of bonding can be increased, and the bonding speed can be increased. An object of the present invention is to provide a wire bonding apparatus. Another object of the present invention is to provide a wire bonding apparatus capable of improving the reproducibility of loop formation and the reproducibility of ball formation by controlling the speed of the operation of the capillary, and improving the accuracy and reliability of bonding.

[0016]

The present invention has the following means in order to achieve the above object. A first invention provides an arm for holding a capillary into which a wire connecting an electrode of a chip and a lead is inserted, a Z-axis driving mechanism having a Z-axis motor for swinging the arm in the vertical Z-axis direction, and a chip. An ITV camera for imaging the upper surfaces of the electrodes and leads and converting an image into an electric signal;
An X-axis moving table having an X-axis motor and a Y-axis moving table having a Y-axis motor for moving a camera in a horizontal plane relative to a chip, and bonding for mounting a lead frame on which a chip to be bonded is mounted. A stage, an image recognizing unit that obtains position information by recognizing a video signal from the ITV camera, and a control microcomputer that receives the image signal from the image recognizing unit and calculates and outputs a trajectory signal that determines the trajectory of the capillary. And a servo drive control unit that receives a locus signal from the control microcomputer and drives the X-axis motor, the Y-axis motor, and the Z-axis motor, wherein the control microcomputer comprises: It is characterized by having a means configuration. (A) Linear function storage means for storing a linear function in which the movement trajectory of the capillary is a straight line. (B) Bezier function storage means for storing a Bezier function in which the movement trajectory of the capillary is a Bezier curve. Linear function loop control means for controlling to move (4) Bezier function loop control means for controlling the capillary to move on the locus of the Bezier curve

According to a second aspect of the present invention, in the control microcomputer of the first aspect, instead of the Bezier function storage means described in (B) and the Bezier function loop control means described in (D),
A wire bonding apparatus having the following means (b) and (d). (B) Spline function storage means for storing a spline function whose capillary movement trajectory is a spline curve. (D) Spline function loop control means for controlling the capillary to move along the trajectory of the spline curve.

A third aspect of the present invention is a wire bonding apparatus characterized in that the following means is added to the control microcomputer of the first aspect. (A) Composite loop control means for controlling the capillary to move along a locus of one curve obtained by combining an approximate straight line and a Bezier curve

A fourth invention is a wire bonding apparatus characterized in that the following means is added to the control microcomputer of the second invention. (A) Composite loop control means for controlling the capillary to move along a locus of one curve obtained by combining an approximate straight line and a spline curve

According to a fifth aspect of the present invention, there is provided a wire bonding apparatus characterized in that the following means are added to the control microcomputer of the first, second, third or fourth aspect. (A) Speed function storage means for storing a speed function for speed controlling the operation of the capillary (b) Speed control means for speed controlling the operation of the capillary

According to a sixth aspect of the present invention, there is provided a wire bonding apparatus characterized in that the following means are added to the control microcomputer of the first aspect. (A) Spline function storage means for storing a spline function in which the movement trajectory of the capillary is a spline curve (b) Spline function loop control means for controlling the capillary to move along the trajectory of the spline curve (c) Capillary with a straight line and Bezier Compound loop control means for controlling movement along a locus of a single curve combining a curve or a spline curve. (D) Speed function storage means for storing a speed function for speed-controlling the operation of the capillary (e) Operation of the capillary Speed control means for speed control

[0022]

According to the present invention, the moving trajectory from the first bonding point to the second bonding point of the capillary is formed as a straight line, a Bezier curve or a spline curve by each means configuration. The movement locus can be set so that the wire suction performed during the descent is performed smoothly. This forms a good loop. Further, even when the distance from the first bonding point to the second bonding point is increased due to the lengthening of the bonding wire, a good loop is formed and the bonding accuracy can be improved.
Further, in the present invention, the capillary is moved by a complex loop control means along a locus formed by a single curve obtained by combining an approximate straight line and a Bezier curve or a spline curve. Since the stop and start for the direction change is not performed, the time for stabilizing the stationary state can be reduced, the time for wire bonding can be shortened, and the bonding speed can be increased. Further, since the speed is controlled when the capillary moves from the first bonding point to the second bonding point, when the bonding operation is repeated, the moving time and the moving trajectory from the first bonding point to the second bonding point are determined. The reproducibility is improved, and thus the reproducibility of loop formation is improved. As a result, the accuracy and reliability of bonding can be improved. Further, in the present invention, speed control is performed when the capillary rises from the second bonding point and returns to the first bonding point, and a constant speed region is provided while the capillary is rising, and after passing through the constant speed region, the wire clamp clamps the wire. The length of the wire coming out of the tip of the capillary does not vary for each bonding, so that the size of the ball does not vary and the reproducibility of the ball formation is improved, and the bonding accuracy is improved. Can be given.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention relates to an arm for holding a capillary through which a wire connecting a chip electrode and a lead is inserted, and a Z-axis motor for swinging the arm in the vertical Z-axis direction. A Z-axis driving mechanism, an ITV camera for imaging the electrodes of the chip and the upper surfaces of the leads and converting an image into an electric signal, and an X-axis for moving the arm and the ITV camera relative to the chip in a horizontal plane. An X-axis moving table having a motor, a Y-axis moving table having a Y-axis motor, a bonding stage on which a lead frame on which a chip to be bonded is mounted is mounted, and image information from the ITV camera for image recognition and position information , A control microcomputer having an arithmetic function, and a drive for driving an X-axis motor, a Y-axis motor, and a Z-axis motor. A wire bonding apparatus having a servo drive control unit, wherein a trajectory and a speed at which the capillary moves from a first bonding point to a second bonding point are calculated and controlled by a control microcomputer, thereby performing bonding. The loops and balls were formed well, with no variation and good reproducibility.

The control microcomputer includes a loop information storage section and a loop control section, which are connected by a data bus. The loop information storage unit has a linear function storage means and a Bezier function storage means for forming a movement trajectory of the capillary. Further, the loop control unit has a linear function loop control means and a Bezier function loop control means. The capillary is controlled by the linear function loop control means and the Bezier function loop control means so as to move along a trajectory combining a straight line and a Bezier curve. As a result, the reproducibility of loop formation is improved.

The control microcomputer includes a spline function storage unit in place of the Bezier function loop control unit of the loop information storage unit, and a spline function loop control unit in place of the Bezier function loop control unit of the loop control unit. This makes it possible to control the capillary so as to move along a trajectory combining a straight line and a spline curve.

Further, by adding compound loop control means to the loop control section, the moving trajectory of the capillary by the linear function loop control means and the Bezier function loop control means is obtained by combining an approximate straight line and a Bezier curve with the capillary. The direction is controlled so as to form a single curve in which the direction change is performed smoothly. Also, a spline function loop control means can be used instead of the Bezier function loop control means,
Control can be performed so that the movement trajectory becomes a single curve obtained by combining the approximate straight line and the Bezier curve. As a result, the time for forming the loop is shortened.

By adding a speed function storage means to the loop information storage section and a speed control means to the loop control section included in the control microcomputer, a horizontal plane is provided when the capillary moves from the operation start position to the target position. The trajectory in the horizontal plane becomes a straight line in any direction as long as the moving distance in the same direction is the same, and control is performed such that the operation is performed in the same required time. As a result, the wire can be stretched straight in a horizontal plane, and the wire being bonded can be prevented from contacting an adjacent wire. Also, the first
The moving time of the capillary from the bonding point to the second bonding point is the same. As a result, the reproducibility of loop formation is improved.

Further, by controlling the speed control means so as to provide a constant speed area on the way of the capillary rising from the second bonding point to the spark point,
The length of the wire emerging from the tip of the capillary to form the next bonding ball can be made constant.
As a result, there is no variation in the size of the ball, and the reproducibility of the ball formation is improved.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the wire bonding apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the first invention of the wire bonding apparatus of the present invention. In FIG. 1, an X-axis moving table 22 having an X-axis motor 21 and a Y-axis moving table 24 having a Y-axis motor 23 are provided on a base 20, and the X-axis motor 21 and the Y-axis motor 23 are provided. The table moves in the horizontal plane by the rotation of. A Z-axis driving mechanism 25 is provided on the Y-axis moving table 24, and the Z-axis driving mechanism 25 is rotatably supported on a holding block 27 by a support shaft 26. An arm 28 extends from the Z-axis drive mechanism 25, and a capillary 30 through which a wire 29 is inserted is held at the tip of the arm 28. The Z-axis drive mechanism 25 has a Z-axis motor 32 for swinging the arm 28 up and down. A wire clamp 40 for holding and cutting the wire 29 is provided on the upper part of the capillary 30.

A bonding stage 33 for mounting a lead frame 51 on which a chip 50 to be bonded is mounted is provided on the base 20. Chip 5
0 has an electrode 52, and the electrode 52 and the lead 53 are connected by a wire 29 by bonding. A holder 34 extends beside the Z-axis drive mechanism 25 on the Y-axis moving table 24, and an ITV camera 35 is fixed to the holder 34. The ITV camera 35 is movable within a horizontal plane with respect to the bonding portion, and captures an image of the bonding portion to read an image and convert it into an electric signal. The image recognition unit 36 recognizes an image of the video signal read by the ITV camera 35 and outputs positioning information necessary for wire bonding to the control microcomputer 1.

The control microcomputer 1 controls the position of the capillary 30 based on the positioning information. The control microcomputer 1 includes a loop information storage unit 2 and a loop control unit 3 and is connected by a data bus 4.
The loop information storage unit 2 stores a linear function storage unit 5 and a Bezier function storage unit 6 for forming a movement trajectory of the capillary 30. The linear function storage means 5 stores a linear function formula and is read out when the moving trajectory of the capillary 30 is a straight line. The Bezier function storage means 6 stores a Bezier function formula and is read out when the movement trajectory of the capillary 30 is a Bezier curve. The loop controller 3 has a linear function loop controller 7 and a Bezier function loop controller 8. The linear function loop control means 7 reads out the linear function expression stored in the linear function storage means 5 and
Is controlled to move along a linear trajectory. The Bezier function loop control means 8 reads out the Bezier function formula stored in the Bezier function storage means 6 and controls the capillary 30 to move along the locus of the Bezier curve. The loop controller 3 controls the X axis and the Y axis when the capillary 30 moves from the first bonding point of the electrode 52 to the second bonding point of the lead 53.
The parameters of the position on the axis and the Z axis can be set. Using these parameters, the loop control unit 3 moves the capillary 30 along the determined trajectory and outputs a control signal for operating the wire bonding apparatus.

The servo drive control unit 39 includes the loop control unit 3
By rotating the X-axis motor 21 and the Y-axis motor 23 according to the signal from the X-axis moving table 22, the X-axis moving table 22 and the Y-axis moving table 24 are moved in the horizontal plane. Further, the servo drive controller 39 drives the Z-axis motor 32 to swing the arm 28 up and down. Thus, the capillary 30 moves along a locus determined from the first bonding point to the second bonding point.

Next, the configuration of the control microcomputer according to the second, third, fourth, fifth and sixth embodiments of the present invention will be described in detail with reference to FIG. FIG. 2 is a block diagram for explaining the configuration of the control microcomputer according to the second, third, fourth, fifth and sixth embodiments of the present invention. The control microcomputer according to the second invention replaces the Bezier function storage means 6 of the loop information storage unit 2 included in the control microcomputer 1 of the first invention with a spline function storage means 12, and controls the loop control unit 3. The Bezier function loop control means 8 is replaced with a spline function loop control means 14. The spline function storage means 12 stores a spline function and is read out when the movement trajectory of the capillary 30 is a spline curve. The spline function loop control means 14 reads out the spline function stored in the spline function storage means 12, and controls the capillary 30 to move along the locus of the spline curve.

The control microcomputer according to the third invention is obtained by adding a composite loop control means 15 to the loop control section 3 included in the control microcomputer 1 according to the first invention. The composite loop control means 15 reads out the functions stored in the linear function storage means 5 and the Bezier function storage means 6 and controls the capillary 30 to move along the locus of one curve obtained by combining the approximate straight line and the Bezier curve. .

The control microcomputer according to the fourth aspect of the present invention is obtained by adding a composite loop control means 15 to a loop control section included in the control microcomputer according to the second aspect of the present invention. The composite loop control means 15 reads out the functions stored in the linear function storage means 5 and the spline function storage means 12, and controls the capillary 30 to move along a locus of one curve obtained by combining an approximate straight line and a spline curve. .

A control microcomputer according to a fifth aspect of the present invention includes a speed function storage means 13 in a loop information storage section included in the control microcomputer according to the first, second, third or fourth aspect of the invention, and a loop control section. And a speed control means 16 are added to FIG. The speed function storage means 13 stores a speed function and is used for speed control of the capillary 30. The speed control unit 16 reads out the function stored in the speed function storage unit 13 and controls the speed when the capillary 30 moves from the operation start position to the target position.

As shown in FIG. 2, the control microcomputer 9 of the sixth invention has a spline function storage unit 12 and a speed function storage unit in the loop information storage unit 2 included in the control microcomputer 1 of the first invention. 13, a loop information storage unit 10 to which a loop control unit 13 is added, a loop control unit 11 to which a spline function loop control unit 14, a composite loop control unit 15, and a speed control unit 16 are added to the loop control unit 3. Connected by The function of each means configuration is as described above.

Next, the operation of the wire bonding apparatus according to the first aspect of the present invention will be described with reference to FIGS. FIG. 3 is a diagram showing the movement locus of the capillary in the operation of the first invention of the present invention. According to FIG. 1, the chip 50 is mounted on the upper surface of the lead frame 51 on the bonding stage 33. Prior to performing wire bonding, the electrodes 52 and the leads 53 of the chip 50 are
The image is captured by the TV camera 35. This image is converted into an electric signal, the image is recognized by the image recognition unit 36, the bonding position is detected, and sent to the control microcomputer 1. The control microcomputer 1 uses this position information and the parameters of the movement trajectory of the capillary 30 set by the loop control unit 3 included in the control microcomputer 1, and when the capillary 30 rises, a linear trajectory is used. When descending, a control signal is generated which moves on the locus of the Bezier curve. With this control signal, the servo drive control unit 39
The shaft motor, the Y-axis motor, and the Z-axis motor are driven to move the capillary 30.

When the capillary 30 moves from the first bonding point to the second bonding point, the wire 29 inserted into the capillary 30 spans the two points, and the electrode 52 of the chip 50 and the lead 53 are looped by the wire 29. And are connected. When the connection is completed, the capillary 30 moves up, moves to the first bonding point, and moves to the next bonding operation. When the capillary 30 ascends, the wire 29 at the top of the capillary 30 closes and moves upward to cut the wire 29, and then a ball is formed by sparking for the next bonding.

Next, FIG. 4 shows the movement locus of the capillary.
It will be explained using. FIG. 4 shows a first or second embodiment of the present invention.
The moving trajectory of the Akira capillary in a three-dimensional graph
It is. According to FIG. 4, in the first invention, the capillary 30 is used.
Is P at the first bonding point₀To P₁Until it rises in a straight line
Then P₁To P₂Up to the direction of the second bonding point
Move horizontally in the opposite direction and move straight₂From the highest position P₃
Up to a linear function loop control means 7
Controlled by P₃To P ₄, P₅Via the second button
Ending point P_nUntil it descends on the locus of a Bezier curve
As described above, the control is performed by the Bezier function loop control means 8.
In FIG.₃To P₄, P₅The second Bon via
The trajectory indicated by the dotted line up to the
Free trajectory can be obtained by changing the constant. 1st bondy
Point P₀And P at the second bonding point_nOn the Z axis of
The difference D corresponds to the height of the chip 50. Also in the second invention
Is P₀To P₂The trajectory up to is the same as that of the first invention.
You. P ₃To P₄, P₅Via the second bonding point
P_nUp to the point along the locus of the spline curve.
It is controlled by the pipeline function loop control means 14.

Next, the capillary by the composite loop control means
Is described with reference to FIG. Figure 5 is a book
According to the composite loop control means of the third or fourth invention,
Of the moving trajectory of the capillary
is there. According to FIG. 5, in the third invention, the capillary 30
Is a single curve that combines an approximate straight line and a Bezier curve.
Composite loop control means 1 to move along the created trajectory
5 is controlled. As a result, the capillary 30 is moved to FIG.
Of the first bonding point as well as the locus of₀To P₁Until
Rises along the locus of the approximate straight line, and P₁To P₂Until the second button
Horizontal movement along the approximate straight line trajectory in the direction opposite to the binding point
Then P₂From the highest position P₃Up to the locus of the approximate straight line
Rise, P₃To P₄, P₅Second bonding via
Point P_nUntil it descends on the locus of the Bezier curve. First bon
P of the ding point₀And P at the second bonding point _nOn the Z axis
Corresponds to the height of the chip 50. In the fourth invention
Indicates that the capillary 30 combines an approximate straight line and a spline curve.
Move along a trajectory created by one combined curve
Is controlled by the composite loop control means 15.

Next, the speed control of the capillary will be described with reference to FIG. FIG. 6 is a graph for explaining the operation of the speed control means of the fifth invention of the present invention. According to Figure 6, when the capillary 30 is moved from the operation start position _{Q 0} to the target position _{Q n,} passing time _{t 1,} t 2, _t passing point in _{n Q 1, Q 2, Q} n X -axis coordinate of the X ₁ , X ₂ ,
X _n and Y-axis coordinate _{Y 1,} Y 2, setting the _{Y n} to the speed control means 16 as a parameter. As a result, the speed control means 16 controls the trajectory in the horizontal plane to be a straight line in any direction as long as the capillary 30 has the same moving distance in the horizontal plane, and controls the operation in the same required time. As a result, the wire 29 can be stretched straight in the horizontal plane, and the wire being bonded can be prevented from contacting the adjacent wire. Also, the second bonding point from the first bonding point
The moving time of the capillary 30 to the bonding point becomes the same, and the reproducibility of loop formation can be improved.

Next, speed control when the capillary rises from the second bonding point will be described with reference to FIG. FIG. 7 is a graph for explaining a speed change when the capillary rises from the second bonding point in the operation of the speed control means of the fifth invention of the present invention. According to FIG.
When the capillary 30 is raised from the second bonding point P _n to the spark point S _m, it is controlled by the speed control unit 16 so that a constant speed region from S ₁ on the way to S ₂ moves at a constant speed. Meanwhile clamping signal wire clamp 40 is issued in S _1. However, a pinch signal is output and the wire 29
There has time delay before it is cut is nipped, the time delay wire 29 because they are almost the same set as the operation time of the S ₂ from S ₁ is cut by S _2. As a result, the capillary rises by a certain distance in the constant speed region, and the length of the wire from which the tip of the capillary for the next bonding is projected is stabilized.

[0044]

As described above, the wire bonding apparatus of the present invention has the following effects. The first effect is that the capillary moves from the first bonding point to the second bonding point along a trajectory of a straight line and a Bezier curve or a spline curve, so that the capillary inside the wire insertion hole during the movement of the capillary is moved. The wire passes smoothly and a good loop is formed. Further, even when the distance from the first bonding point to the second bonding point is long, a good loop is formed. As a result, the accuracy and reliability of bonding can be improved.

The second effect is that the composite loop control means causes the capillary to move along a locus formed by a single curve obtained by combining a straight line and a Bezier curve or a spline curve. Since the conventional method does not perform the stop / start operation for changing the direction as in the prior art, the time for stabilizing the stationary state can be reduced, and the time for wire bonding can be shortened. As a result, the bonding speed can be increased.

The third effect is that speed control is performed when the capillary moves from the first bonding point to the second bonding point. Therefore, when the bonding operation is repeated, from the first bonding point to the second bonding point. , The reproducibility of the movement time and the movement locus is improved, and the reproducibility of the loop formation is improved. As a result, the accuracy and reliability of bonding can be improved.

The fourth effect is that speed control is performed when the capillary rises from the second bonding point and returns to the first bonding point, and a constant speed region is provided while the capillary is rising. The ascending distance is constant and unchanged, and the length of the wire protruding from the tip of the capillary does not vary for each bonding, so that the size of the ball does not vary and the reproducibility of ball formation is improved. As a result, bonding accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a wire bonding apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram for explaining a configuration of a control microcomputer according to a second, third, fourth, fifth and sixth embodiments of the present invention;

FIG. 3 is a diagram showing a movement locus of a capillary in the operation of the first invention of the present invention.

FIG. 4 is a diagram showing a moving trajectory of the capillary according to the first or second invention of the present invention in a three-dimensional graph.

FIG. 5 is a diagram showing a three-dimensional graph of a trajectory of a capillary by a composite loop control means according to the third or fourth invention of the present invention.

FIG. 6 is a graph for explaining the operation of the speed control means of the fifth invention of the present invention.

FIG. 7 is a graph for explaining a speed change when a capillary rises from a second bonding point in the operation of the speed control means of the fifth invention of the present invention.

FIG. 8 is a block diagram illustrating an example of a configuration of a conventional wire bonding apparatus.

FIG. 9 is a three-dimensional graph showing the movement trajectory of the capillary during the operation of the conventional wire bonding apparatus of FIG.

[Explanation of symbols]

 Reference Signs List 1 control microcomputer 2 loop information storage unit 3 loop control unit 4 data bus 5 linear function storage unit 6 Bezier function storage unit 7 linear function loop control unit 8 Bezier function loop control unit 9 control microcomputer 10 loop information storage unit 11 Loop control unit 12 Spline function storage means 13 Speed function storage means 14 Spline function loop control means 15 Composite loop control means 16 Speed control means 20 Base 21 X-axis motor 22 X-axis movement table 23 Y-axis motor 24 Y-axis movement table 25 Z Axis drive mechanism 26 Support shaft 27 Holding block 28 Arm 29 Wire 30 Capillary 32 Z-axis motor 33 Bonding stage 34 Holder 35 ITV camera 36 Image recognition unit 37 Control unit 38 Loop control unit 39 Servo drive control unit 40 Wire clamp 50 chip 51 lead frame 52 electrode 53 lead

Claims (8)

[Claims] 1. A Z-axis drive mechanism having a capillary into which a wire connecting a chip electrode and a lead is inserted, an arm holding the capillary, and a Z-axis motor for swinging the arm in the vertical Z-axis direction. And an X-axis motor having an ITV camera for imaging the electrodes of the chip and the upper surfaces of the leads and converting an image into an electric signal, and an X-axis motor for moving the arm and the ITV camera relative to the chip in a horizontal plane. A Y-axis moving table having a table and a Y-axis motor, a bonding stage for mounting a lead frame on which a chip is mounted, an image recognition unit for recognizing a video signal from the ITV camera to obtain position information, and an image recognition unit A control microcomputer that receives an image signal from the microcomputer and calculates and outputs a trajectory signal that determines the trajectory of the capillary;
In a wire bonding apparatus having a servo drive control unit that receives a locus signal from a control microcomputer and drives the X-axis motor, the Y-axis motor, and the Z-axis motor, the control microcomputer has the following components. A wire bonding apparatus characterized by the above-mentioned. (A) Linear function storage means for storing a linear function in which the movement trajectory of the capillary is a straight line. (B) Bezier function storage means for storing a Bezier function in which the movement trajectory of the capillary is a Bezier curve. Linear function loop control means for controlling to move (4) Bezier function loop control means for controlling the capillary to move on the locus of the Bezier curve 2. The Bezier function storage means according to (b) in the control microcomputer according to claim 1, and (d).
A wire bonding apparatus having the following configurations (b) and (d) in place of the Bezier function loop control means described above. (B) Spline function storage means for storing a spline function whose capillary movement trajectory is a spline curve. (D) Spline function loop control means for controlling the capillary to move along the trajectory of the spline curve. 3. A wire bonding apparatus according to claim 1, wherein the following configuration is added to the control microcomputer according to claim 1. (A) Composite loop control means for controlling the capillary to move along a locus of one curve obtained by combining an approximate straight line and a Bezier curve 4. A wire bonding apparatus according to claim 2, wherein the following configuration is added to the control microcomputer according to claim 2. (A) Composite loop control means for controlling the capillary to move along a locus of one curve obtained by combining an approximate straight line and a spline curve 5. A wire bonding apparatus according to claim 1, wherein each of the following components is added to the control microcomputer according to claim 1, 2, 3, or 4. (A) Speed function storage means for storing a speed function for speed controlling the operation of the capillary (b) Speed control means for speed controlling the operation of the capillary 6. A wire bonding apparatus according to claim 1, wherein the following components are added to the control microcomputer according to claim 1. (B) Spline function storage means for storing a spline function whose capillary movement trajectory is a spline curve. (B) Spline function loop control means for controlling the capillary to move along the trajectory of the spline curve. Compound loop control means for controlling movement along a locus of a single curve in combination with a Bezier curve or a spline curve. (D) Speed function storage means for storing a speed function for speed-controlling the operation of the capillary. Speed control means for speed control of operation 7. When the capillary moves from the operation start position to the destination position, the trajectory in the horizontal plane is linear and operates in the same required time in any direction as long as the moving distance in the horizontal plane is the same. The wire bonding apparatus according to claim 5 or 6, wherein: 8. The apparatus according to claim 5, wherein the speed control means operates at a constant speed in a predetermined area while the capillary is rising from the second bonding point to the spark point.
Or the wire bonding apparatus according to claim 6.