Wire bonding device

Abstract

To provide a wire bonding device capable of suppressing a failure of an extension of a tail wire.SOLUTION: A wire bonding device comprises: a capillary; an ultrasonic transducer; a clamper that performs a gripping and an open circuit of a wire so that it is communicated with a capillary and is moved to a vertical direction. The control part makes the capillary to be dropped in a state where the clamper is in a closing, and an ultrasonic vibration is applied to the capillary after a time t1 when a tip end of the capillary is grounded in order to start an ultrasonic junction of a lead to the wire. At a time t2 when a predetermined period DL elapses, the clamper 17 is in the closing, and the predetermined period DL is changed in accordance with a period ΔUS of the ultrasonic junction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to the control of the operation of a clamper of a wire bonding apparatus. [Background technology]

[0002] A wire bonding apparatus is used to connect pads of a semiconductor chip and leads of a lead frame with a metal wire. In the wire bonding apparatus, a wire is extended from the tip of a capillary, and the wire is made into an initial ball by a discharge torch or the like, and then the capillary is bonded to a first bond point. Then, the capillary is raised while the wire is being paid out, and looped toward a second bond point, and then the capillary is bonded to the second bond point. Then, when bonding to the second bond point is completed, the capillary is raised to pay out the wire to the tip of the capillary, and then the clamper is closed and the capillary and the clamper are further raised, so that the wire is cut with a predetermined length of tail wire extended from the tip of the capillary. Then, while moving the capillary above the next first bond point, the tail wire is formed into an initial ball by sparks from the discharge torch. Then, bonding is performed to the next first bond point. By repeating such a bonding cycle, the pads and the leads are successively connected (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5117462 specification Summary of the Invention [Problem to be solved by the invention]

[0004] When wire bonding is performed using the conventional technique described in Patent Document 1, the bonding of the wire to the second bond point may be insufficient, making it impossible to extend the tail wire, and causing the bonding device to stop.

[0005] Therefore, an object of the present disclosure is to suppress poor extension of a tail wire in a wire bonding apparatus. [Means for solving the problem]

[0006] The wire bonding apparatus of the present disclosure is a wire bonding apparatus comprising a capillary through which a wire is inserted and which bonds the wire extending from the tip to a bonding target, an ultrasonic vibrator which ultrasonically vibrates the capillary, a clamper which moves up and down in conjunction with the capillary to grip and release the wire, and a control unit which adjusts the movement of the capillary, the opening and closing of the clamper, and the operation of the ultrasonic vibrator, wherein the control unit lowers the capillary with the clamper closed to ground the tip of the capillary to the bonding target, and then ultrasonically vibrates the capillary with the ultrasonic vibrator to start ultrasonic bonding of the wire to the bonding target, and opens the clamper after a predetermined period of time has elapsed after the start of ultrasonic bonding, and changes the predetermined period of time depending on the duration of ultrasonic bonding.

[0007] In this way, by making it possible to adjust the specified period from the start of ultrasonic bonding to the opening of the clamper, the wire can be reliably bonded to the second bonding point before the clamper is opened, thereby preventing poor extension of the tail wire.

[0008] In the wire bonding apparatus of the present disclosure, the predetermined period may be 10% to 90% of the ultrasonic bonding period.

[0009] This allows the clamper to be opened after the wire has been reliably bonded to the second bonding point, thereby preventing poor extension of the tail wire.

[0010] In the wire bonding apparatus of the present disclosure, if the period from the start of ultrasonic bonding to when the clamper is fully opened is longer than the ultrasonic bonding period, the control unit may extend the ultrasonic bonding period until the clamper is fully opened.

[0011] This allows ultrasonic bonding to be stopped after the clamper is fully opened, so that the wire can be reliably bonded to the second bonding point before the clamper is opened, thereby preventing poor extension of the tail wire. Effect of the Invention

[0012] The present disclosure can suppress failure of tail wire extension in a wire bonding apparatus. [Brief description of the drawings]

[0013] [Figure 1] 1 is an elevational view showing a configuration of a wire bonding apparatus according to an embodiment; [Diagram 2] 5A to 5C are explanatory diagrams showing a process of bonding wires between a semiconductor chip and a lead using the wire bonding apparatus of the embodiment. [Diagram 3] 4 is a timing chart showing ultrasonic bonding and the timing of opening a clamper. [Figure 4] 10A to 10C are explanatory diagrams showing a process of extending a tail wire using the wire bonding apparatus of the embodiment. [Diagram 5] 13 is a timing chart in the case where the ultrasonic bonding period is extended. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the wire bonding apparatus 100 of the embodiment will be described with reference to the drawings. As shown in Fig. 1, the wire bonding apparatus 100 of the embodiment includes a base 10, an XY table 11, a bonding head 12, a Z-direction motor 13, a horn holder 14, an ultrasonic horn 15, an ultrasonic transducer 16, a capillary 20, a clamper 17, a clamper drive unit 17a, a discharge electrode 18, a bonding stage 19, and a control unit 60. In the following description, the direction in which the horn holder 14 or the ultrasonic horn 15 extends is defined as the X-direction, the direction perpendicular to the X-direction on a horizontal plane is defined as the Y-direction, and the vertical direction is defined as the Z-direction.

[0015] The XY table 11 is attached on the base 10 and moves anything mounted thereon in the X and Y directions.

[0016] The bonding head 12 is attached on an XY table 11 and moved in the X and Y directions by the XY table 11. A Z-direction motor 13 and a horn holder 14 driven by the Z-direction motor 13 are stored inside the bonding head 12. The Z-direction motor 13 is equipped with a stator 13b. The horn holder 14 has a base portion 14a facing the stator 13b of the Z-direction motor 13, and serves as a rotor that is rotatably attached around the shaft 13a of the Z-direction motor 13. An ultrasonic vibrator 16 is attached inside the tip of the horn holder 14.

[0017] An ultrasonic horn 15 is attached to the tip of the horn holder 14 in the X direction, and a capillary 20 is attached to the tip of the ultrasonic horn 15. The ultrasonic horn 15 ultrasonically vibrates the capillary 20 attached to the tip by vibration of the ultrasonic transducer 16. A through hole is provided inside the capillary 20 that passes through in the vertical direction, and a wire 41 is inserted into the through hole.

[0018] A clamper 17 and a clamper driver 17a are provided above the ultrasonic horn 15. The clamper 17 moves up and down in conjunction with the capillary 20, and opens and closes by the operation of the clamper driver 17a to grip and release the wire 41.

[0019] A discharge electrode 18 is provided above the bonding stage 19. The discharge electrode 18 may be attached to a frame (not shown) provided on the base 10. The discharge electrode 18 generates a discharge between the tail wire 46 (see FIG. 4) that is inserted into the capillary 20 and extends from the tip 25 of the capillary 20, and the tail wire 46 is melted to form the initial ball 42.

[0020] The bonding stage 19 adheres to and fixes the substrate 30 having the semiconductor chip 35 mounted on its upper surface, and heats the substrate 30 and the semiconductor chip 35 with a heater (not shown).

[0021] When the base portion 14a of the horn holder 14, which constitutes a rotor, rotates as shown by the arrow 91 in Figure 1 due to the electromagnetic force of the stator 13b of the Z-direction motor 13 of the bonding head 12, the capillary 20 attached to the tip of the ultrasonic horn 15 moves in the Z direction as shown by the arrow 92. Also, the bonding stage 19 moves in the XY directions by the XY table 11. Therefore, the capillary 20 moves in the XYZ directions by the XY table 11 and the Z-direction motor 13.

[0022] The control unit 60 is a computer including a CPU 61, which is a processor that performs information processing therein, and a memory 62 that stores operation programs, operation data, etc. The operation of the control unit 60 is realized by the CPU 61 executing the operation programs stored in the memory 62.

[0023] The XY table 11 , the Z-direction motor 13 , the ultrasonic transducer 16 , the clamper driver 17 a , the discharge electrode 18 , and the bonding stage 19 are connected to a control unit 60 and operate based on commands from the control unit 60 .

[0024] Next, the operation of the wire bonding apparatus 100 of the embodiment will be described with reference to Figures 2 to 4. In the following explanation, the operation of bonding a wire 41 from a pad 36 of a semiconductor chip 35 to a lead 31 of a substrate 30 will be described. In this case, the pad 36 becomes a first bonding point, and the lead 31 becomes a second bonding point. Furthermore, the substrate 30 and the semiconductor chip 35 are bonding targets to which the wire 41 is bonded.

[0025] 2, the control unit 60 generates a discharge between the discharge electrode 18 and the tail wire 46 (see FIG. 4) extending from the tip 25 of the capillary 20, and melts the tail wire 46 to form the initial ball 42. Then, the control unit 60 aligns the central axis of the capillary 20 with the center of the pad 36 by using the XY table 11.

[0026] The control unit 60 closes the clamper 17 using the clamper driving unit 17a, and drives the Z-direction motor 13 to lower the capillary 20 as shown by the arrow 93 in Fig. 2, thereby pressing the initial ball 42 onto the pad 36 to form the disk-shaped compressed ball 43. At this time, the control unit 60 ultrasonically vibrates the capillary 20 using the ultrasonic vibrator 16. As a result, the compressed ball 43 is ultrasonically bonded to the pad 36.

[0027] Next, the control unit 60 drives the clamper driving unit 17a to open the clamper 17, and drives the XY table 11 and the Z-direction motor 13 to raise the capillary 20 as shown by the arrow 94 in Fig. 2, and then loops it toward the center of the lead 31 as shown by the arrow 95a in Fig. 2. At this time, since the clamper 17 is open, the wire 41 is paid out from the tip 25 of the capillary 20.

[0028] When the center of capillary 20 is directly above the center position of lead 31, control unit 60 drives clamper driving unit 17a to close clamper 17, and drives Z-direction motor 13 as shown by arrow 95b in Fig. 2 to lower capillary 20, grounding tip 25 to lead 31, and pressing wire 41 against lead 31 with capillary 20. As a result, loop portion 45 is formed.

[0029] When the tip 25 of the capillary 20 is grounded to the lead 31 at time t1 shown in FIG. 3, the control unit 60 starts driving the ultrasonic transducer 16 at time t1. Then, the control unit 60 drives the ultrasonic transducer 16 while pressing the wire 41 against the lead 31 with the tip 25 of the capillary 20 to ultrasonically vibrate the capillary 20, thereby ultrasonically bonding the wire 41 to the lead 31. Then, the control unit 60 stops driving the ultrasonic transducer 16 at time t4 shown in FIG. 3, and ends the ultrasonic bonding. As shown in FIG. 3, the period ΔUS of this ultrasonic bonding is ΔUS=[t4-t1]. When the ultrasonic bonding ends, a stitch bond portion 44 is formed on the lead 31 as shown in FIG. 2.

[0030] The control unit 60 drives the clamper driving unit 17a to change the clamper 17 from the closed state to the open state at time t2, which is delayed by a predetermined period DL from time t1 when ultrasonic bonding is started. The clamper 17 starts to open from the fully closed state at time t2, and is fully open at time t3. This predetermined period DL is set to 10% to 90% of the ultrasonic bonding period ΔUS. Therefore, as the ultrasonic bonding period ΔUS becomes longer, the predetermined period DL also becomes longer, and as the ultrasonic bonding period ΔUS becomes shorter, the predetermined period DL also becomes shorter. In this way, the wire bonding apparatus 100 can change the predetermined period DL according to the ultrasonic bonding period ΔUS.

[0031] When the ultrasonic bonding is completed, the control unit 60 opens the clamper 17 as shown by an arrow 96 in Fig. 4, raises the capillary 20, and pays out the tail wire 46 to the tip 25 of the capillary 20. Thereafter, the control unit 60 drives the clamper driving unit 17a to close the clamper 17, and raises the capillary 20 and the clamper 17 as shown by an arrow 97 in Fig. 4. As a result, the tail wire 46 extended from the tip 25 of the capillary 20 is cut off from the stitch bond portion 44.

[0032] Thereafter, the control unit 60 moves the capillary 20 onto the next pad 36, while forming the tail wire 46 into the initial ball 42 by sparks from the discharge electrode 18. Then, the control unit 60 performs bonding on the next pad 36 in the same manner as described with reference to FIG.

[0033] The wire bonding apparatus 100 described above can change the predetermined period DL from the start of ultrasonic bonding to the opening of the clamper 17 in accordance with the ultrasonic bonding period ΔUS. This allows the clamper 17 to be opened after the wire 41 has been reliably bonded to the lead 31, thereby preventing poor extension of the tail wire 46. Furthermore, since the predetermined period DL is set to 10% to 90% of the ultrasonic bonding period ΔUS, the clamper 17 is not opened immediately before the end of the ultrasonic bonding period ΔUS, and the clamper 17 can be opened after the wire 41 has been reliably bonded to the lead 31, preventing poor extension of the tail wire 46.

[0034] Next, another operation of the wire bonding apparatus 100 will be described with reference to FIG. 5. As shown in FIG. 5, the control unit 60 drives the clamper driving unit 17a at time t5, which is delayed by a predetermined period DL from time t1 when ultrasonic bonding is started, to change the clamper 17 from the closed state to the open state. The clamper 17 starts to open from the fully closed state at time t5. The clamper 17 is not yet fully open at time t4 when ultrasonic bonding is finished. Then, the clamper 17 is fully opened at time t6 after time t4. In this way, when the period DA from the start of ultrasonic bonding until the clamper 17 is fully opened is longer than the ultrasonic bonding period ΔUS, the control unit 60 extends the ultrasonic bonding period ΔUS by the extension period ΔTA until the clamper 17 is fully opened at time t6. As a result, the ultrasonic bonding is finished at time t6 when the clamper 17 is fully opened.

[0035] This makes it possible to prevent the ultrasonic vibration from being stopped before the clamper 17 is fully opened, resulting in insufficient bonding of the wire 41 to the lead 31 and causing poor extension of the tail wire 46.

[0036] The above describes the operation of bonding the wire 41 from the pad 36 of the semiconductor chip 35 to the lead 31 of the substrate 30, but the wire 41 may be bonded in the opposite manner, from the lead 31 to the pad 36. In this case, the lead 31 becomes the first bonding point, and the pad 36 becomes the second bonding point. Then, the initial ball 42 is bonded to the lead 31, and the ultrasonic vibrator 16 is driven to open the clamper 17 to bond the wire 41 to the pad 36 as shown in FIG. 3, and then the capillary 20 is raised to extend the tail wire 46. [Explanation of symbols]

[0037] 10 base, 11 XY table, 12 bonding head, 13 Z direction motor, 13a shaft, 13b stator, 14 horn holder, 14a base portion, 15 ultrasonic horn, 16 ultrasonic transducer, 17 clamper, 17a clamper drive portion, 18 discharge electrode, 19 bonding stage, 20 capillary, 25 tip, 30 substrate, 31 lead, 35 semiconductor chip, 36 pad, 41 wire, 42 initial ball, 43 pressure ball, 44 stitch bond portion, 45 loop portion, 46 tail wire, 60 control portion, 61 CPU, 62 memory, 100 wire bonding device, DA period from start of ultrasonic bonding until clamper is fully opened, DL predetermined period, ΔUS ultrasonic bonding period, ΔTA extension period.

Claims

1. a capillary through which a wire is inserted and which bonds the wire extended from a tip thereof to a bonding target; an ultrasonic vibrator for ultrasonically vibrating the capillary; a clamper that moves vertically in conjunction with the capillary to grip and release the wire; a control unit that adjusts movement of the capillary, opening and closing of the clamper, and operation of the ultrasonic transducer, The control unit is With the clamper closed, the capillary is lowered to bring the tip of the capillary into contact with the bonding target, and then the ultrasonic vibrator ultrasonically vibrates the capillary to start ultrasonic bonding of the wire to the bonding target; After the ultrasonic bonding is started, the clamper is opened after a predetermined period of time has elapsed, Varying the predetermined period of time depending on the duration of the ultrasonic bonding; A wire bonding apparatus comprising:

2. 2. The wire bonding apparatus according to claim 1, the predetermined period is 10% to 90% of the duration of the ultrasonic bonding; A wire bonding apparatus comprising:

3. 3. The wire bonding apparatus according to claim 2, The control unit is When a period from the start of the ultrasonic bonding until the clamper is fully opened becomes longer than a period of the ultrasonic bonding, the period of the ultrasonic bonding is extended until the clamper is fully opened; A wire bonding apparatus comprising:

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