JPH10107059A - Wire bonder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to continue operation without interrupting apparently even if an undesirable disconnection accident of a wire occurred during operation by a method wherein a disconnection detecting means for detecting the undesirable disconnection of the wire and a reinsertion mechanism, which is vertically moved in the drooping direction of the wire to make the point part of the wire reinsert in a capillary, are annexed to a wire bonder. SOLUTION: A disconnection detecting means 16 is in the state of operation from the start of the operation of a device and monitors the presence or absence of a wire 9 at the upper end part of a capillary 7. A wire reinsertion mechanism 20 opens a wire chuck 19 in a state that an electromagnet is fixed to make the wire 9 possible to be fed out freely. When the wire 9 is disconnected at the part which is fed out from the capillary 7 by some reason, the wire 9 is pulled in the capillary 7 by a back tension and is separated from the point of the wire 9. The means 16 generates a no-wire signal, the chuck 19 is actuated by this signal to pinch the point of the wire 9 and stops the wire 9 from being pulled up. The wire 9 is automatically reinserted in the capillary 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonder used for manufacturing electronic components such as semiconductor devices, and more particularly to a wire bonder having a mechanism capable of self-repairing even if a wire is broken during operation.

[0002]

2. Description of the Related Art In general, electronic components such as semiconductor devices are manufactured by electrically connecting an electronic component body such as a semiconductor pellet and an external lead, and externally covering the electronic component body. Here, an example of a wire bonder for connecting an electrode of an electronic component body and an external lead via a wire will be described with reference to FIG. In the drawing, 1 is a lead frame on which the electronic component body 2 is mounted, 3 is a guide rail for guiding and transporting the lead frame 1, and 4 is an XY disposed on the side of the guide rail 1.
The table 5 is a bonding head supported on the XY table 4 and moves in a horizontal plane.
A horn that is horizontally supported at one end, extends on one end on the guide rail 3, and has an ultrasonic vibrator (not shown) fixed at the other end, and swings around the axis, and the axis is a vertical movement mechanism (not shown) ). Reference numeral 7 denotes a capillary fixed to one end of the horn 6 with its axis directed vertically, 8 denotes a spool around which the wire 9 is wound, and 10 denotes a back tensioner for applying a back tension to the wire 9 drawn from the spool 8. For example, air is blown across the moving path of the wire 9 to apply a force to pull back the wire 9. 11 is a guide member for guiding the wire 9 passing through the back tensioner 10 so as to hang down, and 12 is a horn 6 from the bonding head 5.
A tension clamper 13 has one end fixed to the support plate 12 and the other end clamps the hanging wire 9 with a small pressure to apply tension to the wire 9, and a tension clamper 14 extends below the tension clamper 13. The cut clamper is disposed and one end is fixed to the support plate 12, and the other end is a clamper for appropriately clamping the wire 9. The wire 9 that has passed through the cut clamper 14 is inserted into the capillary 7 so that its tip projects from its lower end. Reference numeral 15 denotes a discharge electrode which is arranged near the lower end of the capillary 7 and reciprocates below the capillary 7 in a horizontal plane. The discharge electrode 15 is connected to a high-voltage power supply (not shown), and discharges between the tip of the wire 9 protruding from the lower end of the capillary 7, and the high heat generated at that time causes the wire 9 to discharge.
Is melted to form a metal ball (not shown). The apparatus is provided with a television camera and an image recognition device for detecting the bonding position by imaging the electrodes on the semiconductor pellet 2, but they are not shown. The operation of this device will be described below. First, the lead frame 1 on the guide rail 3 is positioned at a predetermined position. Next, the wire 9 is protruded from the lower end of the capillary 7 and the wire 9 is cut by the cut clamper 14.
Is clamped, the discharge electrode 15 is moved horizontally below the distal end of the wire 9 to apply a high voltage and discharge to form a metal ball at the distal end of the wire 9. Next, when the cut clamper 14 is opened, the wire 9 is pulled into the capillary 7 by the tension of the back tensioner 10, but the metal ball acts as a stopper and the wire 9 stops at the lower end of the capillary 7. Then, the XY table 4 is operated, and the capillary 7 is moved.
Is moved to the first bonding position on the semiconductor pellet 2 and the horn 6 is rocked while applying ultrasonic vibration to press the metal ball at the lower end of the capillary 7 to the first bonding position for bonding. The horn 6 is further raised, and the wire 9 from the capillary 7 is moved by the XY table 4.
Is raised and moved horizontally to move it to the second bonding position on the lead frame 1. Then, the horn 6 is swung to lower the capillary 7, and the middle portion of the wire 9 is pressed at its lower end while applying ultrasonic vibration to complete the connection. When this connection is completed, the capillary 9 is slightly moved in the horizontal direction to feed out the wire 9, and the cut clamper 14 is operated to cut the wire near the capillary 7 in a state where the wire 9 is prevented from being pulled in. The bonding between the two bonding positions is completed. The above operation is repeated for the remaining portion to be bonded to complete the bonding operation for one semiconductor pellet, the lead frame 1 is moved by one pitch, and the above operation is repeated for the next semiconductor pellet. The wire bonder using the capillary 7 is used for electrical connection of a semiconductor pellet in which a large number of electrodes are arranged along the periphery of the pellet because there is no restriction on the direction in which the wire is drawn. The material and the wire diameter of the wire 9 used for the electrical connection are determined by the current to be handled. In a semiconductor integrated circuit device having a large number of electrodes and handling a small current, for example, a diameter of 15 μm to
A thin gold wire of 32 μm is used. In this apparatus, before starting the operation, the wire 9 drawn out of the spool 8 must be inserted into the capillary 7 so that bonding can be performed. Therefore, first, the operation of the back tensioner 10 is stopped, and the wire 9 fed from the spool 8 is passed through the back tensioner 10. Then, the back tensioner 10 is operated so that the unwound wire 9 is not slackened, and the wire drawing direction is changed along the guide member 11 so that the wire 9 hangs down. Further, the wire 9 is expanded and pushed so that the wire 9 can be inserted into the tension clamper 13, and the wire 9 is inserted, and the wire 9 is inserted with a slight tension applied thereto. The cut clamper 14 is opened in advance, the wire 9 is inserted, the wire 9 is inserted into the capillary 7, and the wire clamp 9 is clamped by operating the cut clamper 14 with the tip protruding from the lower end of the capillary 7. The preparation before starting the operation is completed by preventing the wire 9 from coming off the capillary 7 due to the back tension. The opening diameter of the lower end of the capillary 7 is determined by the diameter of the wire 9, and the diameter of the opening is increased upward and the opening diameter of the upper end is 1.
Although it is set to about mm, it is difficult to insert the wire 9 with bare hands or gloves, so that tweezers is usually used.

[0003]

By the way, tweezers are used for the above-mentioned work for mounting the wire 9 on the wire bonder. However, the work itself is complicated with a thin gold wire because the material itself is very soft and deforms with a slight force. On the other hand, during the wire bonding operation, if the heat generated by the discharge is small, or if the position of the discharge electrode and the tip of the wire is displaced during the discharge, the melting of the metal at the tip of the wire is biased and the shape of the ball becomes asymmetric, so that the ball is heated at the lower end of the capillary 7. When the wire is pressed, stress may be concentrated on the connection between the metal ball and the wire, and the wire may be cut. Further, even if the shape of the metal ball is good, the portion of the wire connected to the metal ball becomes brittle due to the cooling state of the metal ball, and the wire may be broken by a slight force of drawing the wire. However, after the metal ball is connected, the cut clamper 14 is opened to draw out the wire from the capillary 7, and when the wire 9 is cut, the wire tip is pulled into the capillary 7 by the back tension, and the cut clamper 14 is further cut. In some cases, the wire 9 comes off from the tension clamper 13, the guide member 11, and the back tensioner 10, and the bonding operation cannot be continued. When the wire 9 deviates from the routing route in this way, it is necessary to stop the equipment and perform the wire insertion work again, but this work requires skill, and even a skilled person may take several minutes, Even if the frequency of such accidents is small, it cannot be ignored when the number of installed facilities is large, and improvement has been desired. For this reason, there is a method in which a defective molding of the metal ball is detected, the operation of the back tensioner is stopped, or the tension clamper is operated so that the wire does not fall out of the capillary even when the cut clamper is opened. (See, for example, Japanese Utility Model Laid-Open No. 1-67745 and Japanese Utility Model Laid-Open No. 2-21737.) Further, there is also a configuration in which the amount of wire drawn out from the capillary is set to be constant so that a metal ball is always formed. (See, for example, Japanese Unexamined Utility Model Application Publication No. 1-67745). Further, there is a method in which the bonding state is determined from the waveform of the ultrasonic vibration during the bonding operation and the bonding operation is stopped. (For example, see JP-A-62-23433)
Further, it is detected whether or not a ball has been formed at the tip of the wire. If no ball has been formed, the bonding operation is stopped, the wire is drawn out from the tip of the bonding tool, the ball is formed, and the bonding process is performed. It is intended to continue. (For example, Japanese Patent Application Laid-Open No. 62-104126)
However, these are all directed to defective molding of the metal ball in the stage of forming the metal ball and breakage of the wire, and the metal ball is connected to the semiconductor pellet and the wire is cut in a state where the cut clamper is opened. Could not cope with the disconnection at the time of feeding, and did not solve the above problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, and is intended to move a wire which is unwound from a spool, has an intermediate portion or a tip portion hanging down, and a tip portion inserted through a capillary. Along the route, a back tensioner that applies back tension to the wire, a tension clamper that applies tension by clamping the wire in the hanging region of the wire, and a wire that is appropriately clamped below the tension clamper to prevent wire pull-in Disconnection detecting means for sequentially disposing cut clampers, forming a metal ball at the tip of the wire and electrically connecting the first and second bonding portions to a wire bonder for detecting an undesired disconnection of the wire; Clamps the vicinity of the tip of the wire pulled up by the back tensioner based on the detection output of the disconnection detection means. Moves up and down in the hanging direction of the wire, providing a wire bonder, characterized in that it has attached a wire re-interpolation mechanism for inserted again the wire tip into the capillary.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wire bonder according to the present invention comprises a conventional apparatus for detecting a disconnection detecting means for detecting an undesired disconnection of a wire, and for detecting the vicinity of the tip of the wire pulled up by a back tensioner based on a detection output of the disconnection detecting means. A wire reinsertion mechanism for clamping and moving up and down in the direction in which the wire hangs to reinsert the tip of the wire into the capillary is provided, but the wire reinsertion mechanism can be shared by a cut clamper. In addition, the operation of the apparatus of the present invention can be further ensured by arranging a wire guide that regulates the positional deviation of the wire tip at least below the wire reinsertion mechanism. An optical sensor is used as a means for detecting a break in the wire, and this optical sensor can detect the presence or absence of the wire at the upper end of the capillary in the wire movement path. With this optical sensor, it is possible to know that the wire has actually been cut, and it is also possible to know the tip position of the cut wire. By knowing the tip position of the cut wire in this way, it is possible to set the wire feeding amount by the wire reinsertion mechanism based on the height position data.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is applied to the apparatus shown in FIG.
Description will be given from FIG. 1 and FIG. In the figure, the same reference numerals as those in FIG. In the figure, 16
Is a sensor that is arranged on both sides of the wire 9 near the upper end of the capillary 7 and detects the presence or absence of the wire 9 to detect a break in the wire, and specifically includes a light source 16a and an optical sensor 16b. 17 is a rod 1 fixed to the side wall of the support plate 12.
A cylinder for reciprocating the 7a up and down, 18 is an arm having one end fixed to the rod 17a and an intermediate portion to the other end extending along the horn 6, 19 is fixed to the other end of the arm 18,
A movable part is disposed with the moving path of the wire 9 interposed therebetween, and is opened and closed by a wire chuck for clamping the wire 9. As shown in FIG. 3, a fixed block 19 a fixed to the arm 18 and a movable block 19 b are opened and closed by a shaft 19 c. Freely facing,
An elastic force is applied outward by a leaf spring 19d. Usually, a fixed block 19a and a movable block 19b are provided on both sides of the wire 9.
Are separated from each other. 19e is a fixed block 19a
An electromagnet 19f is embedded in the movable block 19b and a magnetic attraction piece facing the electromagnet 19e.
By operating 9e, the fixed block 19a and the movable block 19b hold the wire 9 therebetween. This cylinder 1
7, the arm 18, and the wire chuck 19 constitute a wire reinsertion mechanism 20. The operation of this device will be described below. The disconnection detecting means 16 of this apparatus is in the operating state from the start of the operation of the apparatus, and monitors the presence or absence of the wire 9 at the upper end of the capillary 7. Further, the wire reinsertion mechanism 20 opens the wire chuck 19 while the electromagnet 19e is not moved so that the wire 9 can be fed out freely. In this state, the device of the present invention performs a normal bonding operation similarly to the device of FIG. Then, if the wire 9 is broken at a portion fed out of the capillary 7 for some reason, the cut clamper 14 is opened when the wire is fed out, so that the wire 9 is drawn into the capillary 7 by the back tension by the back tensioner 10 and further moved upward. Wire 9
Is removed from the upper end of the capillary 7. When the wire 9 comes off from the capillary 7 in this way, the disconnection detecting means 1
6 generates a no-wire signal, and according to this signal, the electromagnet 19e of the wire chuck 19 is energized to
9 is operated to clamp the cut end of the wire 9 and stop the wire from being pulled up. Since the time from when the disconnection detecting means 16 operates to when the wire chuck 19 operates is substantially constant, the wire 9 held by the wire chuck 19 is
The height position of the tip is also substantially constant. Then the cylinder 17
Is activated, the wire chuck 19 is
Descends and pulls down the wire 9 to bring the tip of the wire 9 close to the upper end opening of the capillary 7. Then, the cut clamper 14 is operated to move the wire 9 above the wire chuck 19.
Then, the wire chuck 19 is opened, and the wire chuck 19 is raised by the cylinder 17. When the wire chuck 19 comes to the upper position, the wire chuck 19 is operated again to hold the wire, and when the holding is completed, the cut clamper 14 is opened and the cylinder 1
7, the wire chuck 19 is lowered. This operation is repeated until the tip of the wire 9 projects from the lower end of the capillary 7. When the work of reinserting the wire 9 into the capillary 7 is completed, the cut clamper 14 is operated to bring the bonding work into an initial state. There are various reasons for the disconnection of the wire, and if it is due to defective ball formation due to discharge mistake, the bonding operation can be continuously performed on the cut semiconductor pellet, but after the metal ball is formed. In the case of cutting, the bonding operation to the cut semiconductor pellet is stopped, and the bonding operation is restarted from the next semiconductor pellet. As described above, even if an undesired disconnection occurs during the wire bonding operation, the device of the present invention can be automatically reinserted into the capillary 7 and these operations can be started in the vicinity of the capillary.
Reinsertion can be performed reliably in a short time of 0 second. Further, the apparatus of the present invention can be applied to an operation of inserting a wire into a capillary before the start of operation, and even an unskilled person can perform a preparation operation reliably in a short time. Therefore, there is no apparent stoppage of the device, and the operation rate of the facility can be improved. The present invention is not limited to the above embodiment. For example, the wire reinsertion mechanism 20 is provided not only separately from the cut clamper 14 but also by attaching a vertical movement mechanism to the cut clamper 14. Can also be used as the wire reinsertion mechanism 20. In this case, when the cut clamper 14 holding the wire 9 to be reinserted is opened and changed, the back tensioner 10
The wire 9 can be prevented from coming off from the cut clamper 14 which is opened by adjusting the strength of the cut clamper 13 so as to be balanced with the tension of the tension clamper 13. Also,
A wire guide that regulates positional deviation of the wire 9 can be arranged at least below the wire chuck 19 of the wire reinsertion mechanism 20 or the cut clamper 14 that also functions as the wire reinsertion mechanism. The wire guide may be formed by shaping a thin metal wire or the like into a ring shape, whereby the tip of the wire can be reliably guided to the upper end opening of the capillary 7. In the above embodiment, the disconnection detecting means 16 is the light source 1.
6a and the optical sensor 16b, these were fixed to the horn 6, but a reflecting mirror was fixed in front of the capillary 7 of the horn 6, and a light source for projecting light to the reflecting mirror on a swing axis portion of the horn 6 was reflected. And an optical sensor for detecting the reflected light. Further, by detecting the height position of the cut end of the wire by the disconnection detecting means 16, the wire feeding amount of the wire reinsertion mechanism 20 can be set based on the height position information.

[0007]

As described above, according to the present invention, even if an undesired disconnection accident occurs during the wire bonding operation, the operation can be apparently continued without interruption.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a front view of a main part of the apparatus in FIG. 1;

FIG. 3 is a plan sectional view of a wire chuck forming a part of a wire reinsertion mechanism of the apparatus in FIG. 1;

FIG. 4 is a side view showing an example of a wire bonder.

[Explanation of symbols]

 7 Capillary 8 Spool 9 Wire 10 Back tensioner 13 Tension clamper 14 Cut clamper 16 Disconnection detecting means 20 Wire reinsertion mechanism

Claims (6)

[Claims] 1. A back tensioner for applying back tension to a wire along a movement path of a wire which is fed out of a spool, has a middle portion or a tip portion hanging down, and a tip portion inserted into a capillary, and a wire hanging region. A tension clamper that clamps the wire to provide tension and a cut clamper that clamps the wire appropriately below the tension clamper and prevents wire pull-in are sequentially arranged, and melts the wire tip protruding from the capillary tip. The metal ball formed by pressing the capillary at the tip of the capillary is connected to the first bonding portion, the cut clamper is opened, the capillary is moved to the second bonding portion while feeding out the wire, and the wire middle portion is pressed by the capillary tip. After the connection, the outside of the wire is cut and the first and second bonding are performed. In a wire bonder connecting the parts with a wire, a wire disconnection detecting means for detecting an undesired disconnection of the wire, and a vicinity of a tip end of the wire pulled up by a back tensioner based on a detection output of the wire disconnection detecting means are clamped, A wire bonder comprising: a wire reinsertion mechanism that vertically moves in a hanging direction to reinsert a wire tip into a capillary. 2. The wire bonder according to claim 1, wherein the wire reinsertion mechanism is a cut clamper. 3. The wire bonder according to claim 1, wherein a wire guide for restricting positional deviation of a wire tip portion is disposed at least below the wire reinsertion mechanism. 4. The wire bonder according to claim 1, wherein the wire disconnection detecting means is a high pressure generating means for forming a molten metal ball at a wire tip by electric discharge. 5. The wire bonder according to claim 1, wherein the wire disconnection detecting means is an optical sensor arranged at the upper end of the capillary across the moving path of the wire. 6. The wire re-insertion mechanism detects the tip of the wire clamped by the wire re-insertion mechanism with an optical sensor, and sets the wire feeding amount by the wire re-insertion mechanism based on the height position data. The wire bonder according to claim 5, wherein