JP7542895B1 - Wire Bonding Equipment - Google Patents

Abstract

[Problem] To suppress poor extension of a tail wire in a wire bonding apparatus. [Solution] The wire bonding apparatus includes a capillary, an ultrasonic vibrator, a clamper that moves up and down in conjunction with the capillary to grip and release the wire, and a control unit, in which the control unit ultrasonically vibrates the capillary with the ultrasonic vibrator to start ultrasonic bonding of the wire to the lead after time t1 when the capillary is lowered with the clamper closed and the tip of the capillary is grounded on the lead, and opens the clamper 17 at time t2 after a predetermined period DL has elapsed, and changes the predetermined period DL according to a period ΔUS of ultrasonic bonding. [Selected Figure] Figure 3

Description

The present invention relates to the operation control of a clamper in a wire bonding device.

A wire bonding device is used to connect the pads of a semiconductor chip and the leads of a lead frame with a metal wire. In the wire bonding device, 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. The capillary is then bonded to the first bond point. The capillary is then raised while the wire is being paid out, and looped toward the second bond point, after which the capillary is bonded to the second bond point. After bonding to the second bond point is completed, the capillary is raised to pay out the wire to the tip of the capillary, and the clamper is then closed and the capillary and the clamper are further raised, cutting the wire 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. This bonding cycle is repeated to sequentially connect the pads and leads (see, for example, Patent Document 1).

Patent No. 5117462 specification

When wire bonding is performed using the conventional technology described in Patent Document 1, the wire may not be bonded sufficiently to the second bond point, preventing the tail wire from extending, causing the bonding device to stop.

Therefore, the present disclosure aims to prevent poor tail wire extension in wire bonding devices.

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 extended 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, then ultrasonically vibrates the capillary with the ultrasonic vibrator to start ultrasonic bonding of the wire to the bonding target, opens the clamper after a predetermined period has elapsed after the start of ultrasonic bonding, and stops ultrasonic bonding after the clamper is fully open, and changes the predetermined period depending on the duration of ultrasonic bonding.

In this way, by making it possible to adjust the predetermined period from the start of ultrasonic bonding to opening 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.

In the wire bonding apparatus disclosed herein, the specified period may be 10% to 90% of the ultrasonic bonding period.

This allows the wire to be reliably bonded to the second bonding point before the clamper is opened, preventing poor extension of the tail wire.

In the wire bonding device disclosed herein, if the period from the start of ultrasonic bonding until 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.

This allows ultrasonic bonding to be stopped only after the clamper is fully opened, so the wire can be reliably bonded to the second bonding point before the clamper is opened, preventing poor extension of the tail wire.

This disclosure can prevent tail wire extension failures in wire bonding devices.

1 is an elevational view showing a configuration of a wire bonding apparatus according to an embodiment; 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. 4 is a timing chart showing ultrasonic bonding and the timing of opening a clamper. 10A to 10C are explanatory diagrams showing a process of extending a tail wire using the wire bonding apparatus of the embodiment. 13 is a timing chart in the case where the ultrasonic bonding period is extended.

The wire bonding apparatus 100 of the embodiment will be described below 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 the X-direction, the direction perpendicular to the X-direction on a horizontal plane is the Y-direction, and the vertical direction is the Z-direction.

The XY table 11 is attached to the base 10 and moves anything mounted on top in the XY directions.

The bonding head 12 is mounted on the 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 mounted around the shaft 13a of the Z-direction motor 13. An ultrasonic vibrator 16 is attached inside the tip of the horn holder 14.

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 the vibration of the ultrasonic transducer 16. The capillary 20 has a through hole that penetrates vertically inside, and a wire 41 is inserted into the through hole.

In addition, a clamper 17 and a clamper driver 17a are provided above the ultrasonic horn 15. The clamper 17 moves vertically in conjunction with the capillary 20, and opens and closes with the operation of the clamper driver 17a to grip and release the wire 41.

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, melting the tail wire 46 to form the initial ball 42.

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).

When the base 14a of the horn holder 14, which constitutes a rotor, rotates as shown by the arrow 91 in FIG. 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. In addition, the bonding stage 19 moves in the XY direction by the XY table 11. Therefore, the capillary 20 moves in the XYZ direction by the XY table 11 and the Z-direction motor 13.

The control unit 60 is a computer that includes a CPU 61, which is a processor that performs information processing, 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.

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

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 the wire 41 from the pad 36 of the semiconductor chip 35 to the lead 31 of the substrate 30 will be described. In this case, the pad 36 becomes the first bonding point, and the lead 31 becomes the second bonding point. Furthermore, the substrate 30 and the semiconductor chip 35 are bonding targets to which the wire 41 is bonded.

As shown in FIG. 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, melting 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 using the XY table 11.

The control unit 60 closes the clamper 17 using the clamper drive unit 17a, and drives the Z-direction motor 13 to lower the capillary 20 as shown by the arrow 93 in FIG. 2, pressing the initial ball 42 onto the pad 36 to form a disk-shaped compressed ball 43. At this time, the control unit 60 ultrasonically vibrates the capillary 20 using the ultrasonic vibrator 16. This ultrasonically bonds the compressed ball 43 to the pad 36.

Next, the control unit 60 drives the clamper drive 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.

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

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. The control unit 60 then 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. The control unit 60 then stops driving the ultrasonic transducer 16 at time t4 shown in FIG. 3, thereby completing the ultrasonic bonding. As shown in FIG. 3, the ultrasonic bonding period ΔUS is ΔUS=[t4-t1]. When the ultrasonic bonding is completed, a stitch bond portion 44 is formed on the lead 31 as shown in FIG. 2.

The control unit 60 drives the clamper drive unit 17a to change the clamper 17 from a closed state to an open state at time t2, which is delayed by a predetermined period DL from time t1 when ultrasonic bonding begins. The clamper 17 starts to open from a 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, if the ultrasonic bonding period ΔUS becomes longer, the predetermined period DL also becomes longer, and if the ultrasonic bonding period ΔUS becomes shorter, the predetermined period DL also becomes shorter. In this way, the wire bonding device 100 can change the predetermined period DL according to the ultrasonic bonding period ΔUS.

When the ultrasonic bonding is completed, the control unit 60 opens the clamper 17 as shown by the arrow 96 in FIG. 4, raises the capillary 20, and pays out the tail wire 46 to the tip 25 of the capillary 20. The control unit 60 then drives the clamper drive unit 17a to close the clamper 17, and raises the capillary 20 and the clamper 17 as shown by the arrow 97 in FIG. 4. This causes the tail wire 46 extended to the tip 25 of the capillary 20 to be severed from the stitch bond portion 44.

Then, the control unit 60 moves the capillary 20 onto the next pad 36, and forms the tail wire 46 into an initial ball 42 by sparks from the discharge electrode 18. The control unit 60 then performs bonding on the next pad 36 in the same manner as described with reference to FIG. 2.

The wire bonding apparatus 100 described above can change the predetermined period DL from the start of ultrasonic bonding to opening the clamper 17 according to the ultrasonic bonding period ΔUS. This allows the wire 41 to be reliably bonded to the lead 31 before the clamper 17 is opened, thereby preventing poor extension of the tail wire 46. In addition, since the predetermined period DL is set to 10% to 90% of the ultrasonic bonding period ΔUS, the clamper 17 will not be opened immediately before the end of the ultrasonic bonding period ΔUS, and the wire 41 can be reliably bonded to the lead 31 before the clamper 17 is opened, preventing poor extension of the tail wire 46.

Next, other operations 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 drive unit 17a at time t5, which is delayed by a predetermined period DL from time t1 when ultrasonic bonding starts, to change the clamper 17 from a closed state to an open state. The clamper 17 starts to open from a fully closed state at time t5. The clamper 17 is not yet fully open at time t4 when ultrasonic bonding ends. The clamper 17 then becomes fully open at time t6 after time t4. In this way, if 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 an extension period ΔTA until the clamper 17 is fully opened at time t6. As a result, ultrasonic bonding ends at time t6 when the clamper 17 is fully opened.

This prevents 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.

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 and bond the wire 41 to the pad 36 as shown in FIG. 3, after which the capillary 20 is raised to extend the tail wire 46.

10 base, 11 XY table, 12 bonding head, 13 Z direction motor, 13a shaft, 13b stator, 14 horn holder, 14a base, 15 ultrasonic horn, 16 ultrasonic transducer, 17 clamper, 17a clamper drive, 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-bonded ball, 44 stitch bond part, 45 loop part, 46 tail wire, 60 control part, 61 CPU, 62 memory, 100 wire bonding device, DA period from start of ultrasonic bonding until the clamper is fully opened, DL predetermined period, ΔUS ultrasonic bonding period, ΔTA extension period.

Claims (3)

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,
After the clamper is fully opened, the ultrasonic bonding is stopped,
Varying the predetermined period of time depending on the duration of the ultrasonic bonding;
A wire bonding apparatus comprising: 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. 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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