JPS60227433A - Ultrasonic wire bonding head - Google Patents

Abstract

PURPOSE:To obtain a wire bonding head with high reliability by clamping wire with a combination of a driving roller and a pressing roller and by driving the driving roller through a pulse motor for supplying wire. CONSTITUTION:When ultrasonic waves are applied to a wedge 8 for bonding a wire 9, a piezoelectric element 10 is shurnk by applying a voltage thereto, whereby an arm 14b is turned around the axis 15 and rollers 12, 13 are separated from each other. The wedge 8 is shifted to draw out the wire 9. The voltage applied to the element 10 is turned OFF when the wedge descends to be bonded. The element 10 is thereby returned to the original state and the arm 14b is turned reversely so that the wire 9 is clamped between the rollers 12 and 13. The wedge 8 is lifted up in this condition. The roller 12 is driven by a pulse motor 11 upon cutting the wire so that further wire 9 is delivered in accordance with the angle of rotation of the roller. The tip of the wire is presented to the tip of the wedge to prepare for the next bonding operation. Usage of the piezoelectric element enables the wire bonder to operate rapidly, and a bonding head with a simple construction and high reliability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Description of the technical field to which the invention pertains] The present invention relates to a structure of a head portion of an ultrasonic wire bonder.

[Description of prior art]

The bonding operation using a conventional ultrasonic wire bonder is as follows. That is, in FIGS. 6 and 7, when the first bonding is performed, the solenoid 2 is displaced, the clamp body 1 is opened, and the wire 9 is freed. Thereafter, the bonding wedge 8 moves to the second bonding point, but since the clamp 1 is opened, the wire 9 is pulled out by the amount that the wedge 8 has moved. In this clamp open state, the clamp body 1 is controlled by the rotation of the cam 4 driven by the motor 5, and is raised to the rear of the bonding wedge 8. At the upper limit, the voltage applied to the solenoid 2 is turned off, and the clamp body 1 is closed by the tension of the spring 3, holding the wire 9 again. Then, the second bond is performed, the bonding wedge 8 is raised, the wire 9 is cut, and at the same time, the cam 4 is rotated by the rotation of the motor 5, and the clamp body 1 returns to the original position while holding the wire 9. Return to This results in wedge 8
The wire 9 is fed about 100 μm below the wire 9 in preparation for the next bonding operation. However, the conventional wire bonder described above has the following drawbacks.

That is, (1) If the displacement width of the wire clamp portion by the solenoid or the tension state of the spring changes from the time of adjustment, the opening/closing response of the clamp deteriorates. ■When wire feeding,
Since the motor rotates the cam and gives the clamp part reciprocating motion, the load on the motor is large and the mechanical structure is complicated, which places a large load on the stage that supports the head part, leading to a decrease in reliability, etc. This is a drawback.

[Detailed description of the invention]

The present invention improves the responsiveness of the opening/closing operation of the clamp and the wire feed operation mechanism, thereby increasing the speed of the bonding operation as shown in FIG. 9, and providing a highly reliable head for an ultrasonic wire bonder.

[Structure of the invention]

In the present invention, a drive roller and a pressure roller, which serve as wire clamps, are mounted facing each other at the ends of a pair of arms connected to be openable and closable, and a piezoelectric displacement element is installed between the bases of both arms, The head for an ultrasonic wire bonder is characterized in that the rotation axis of the drive roller is linked to a pulse motor.

[Explanation of the principle and operation of the invention]

The present invention uses a combination of a pressure roller to clamp the wire, uses the displacement of a piezoelectric element to control the opening and closing of the wire, and furthermore, the wire is clamped between the pressure roller and the drive roller while the drive roller This is done by driving the motor with a pulse motor.

[Detailed description of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 show the structure of the head portion of the ultrasonic wire bonder according to the present invention.

FIG. 4 shows the relationship between the head and the stage. In the figure, a pair of arms 14a and +14b are connected by a support shaft 15.
A drive roller 12 and a pressure roller 13 are mounted facing each other at the tips of the arms 14a and 14b, respectively, and a piezoelectric displacement element 1O is installed between the rear ends of both arms 14a and 14b with the support shaft 15 in between. However, in the embodiment, one arm 14α is attached to the fuselage (as shown)
The figure shows an example in which the fixed arm 14 (L) is supported rotatably around a support shaft 15 with the other arm 14b as a movable arm. 16 is a head mounting hole. Specifically, the roller 12 is mounted on a rotating shaft 18 supported by a bracket 17 at the tip of the arm 14α, and a pulse motor 11 is connected to this rotating shaft 18.The pressure roller 13 is a drive roller. 12, and is rotatably supported at the tip of the movable arm 14b.

The piezoelectric displacement element IO controls the opening and closing of both arms 14α and 14b by using strain caused by the so-called inverse piezoelectric effect as a driving force. The movable arm 14b rotates around the support shaft 15 due to the contraction displacement that occurs when a DC voltage is applied to the piezoelectric displacement element IO, and the pressure roller 13 moves toward the drive roller 12.
When the DC voltage is turned off, the pressure roller 13 is brought into pressure contact with the circumferential surface of the drive roller 12, and the wire is clamped between them.

The pulse motor 11 rotates the drive roller 12 while clamping the wire, thereby giving a constant feed to the wire.

In FIG. 4, 7 is a horn fixed to the stage (path shown). The horn 7 has a Langevin type vibrator (not shown) at its base, and a bonding wedge 8 is attached to its tip. 9 is an aluminum wire. Aluminum wire 9 is guided to bonding wedge 8 through a hole in horn 7. The driving roller 12 and the pressure roller 13 are arranged in relation to each other so that they are placed on both sides of the wire 9. 19 is a head cover. The piezoelectric displacement element lo is attached to this head cover 19.
Keep it inside and isolate it from the outside.

FIGS. 5(a) to (n) show the outline of the actual bonding operation. FIG. 5(a) shows the state at the time of first bonding.

When bonding the wire 9 by applying ultrasonic waves to the wedge 8, when a voltage is applied to the piezoelectric displacement element 10, the piezoelectric displacement element 1o contracts, and in response to the displacement, the arm 14b moves toward the support shaft 1.
5 as a fulcrum, the drive roller 12 and pressure roller 13 are separated, the clamp is opened, and the wire 9
becomes free.

FIG. 5(b) shows a state in which the first bond is completed and the wedge 8 moves toward the second bond point. Since the clamp is open, the wire 9 is kept free and drawn out as the thread 8 moves.

FIG. 5(C) shows the state at the time of second bonding. wedge 8
When bonding the lower shear wire 9, the voltage previously applied to the piezoelectric displacement element IO is turned off.

This causes the piezoelectric displacement element 10 to return to its original dimensions.

Then, the tip of the arm 14b moves inward about the support shaft 15, the pressure roller 13 comes into pressure contact with the drive roller 12, the wire 9 is held between the rollers 12 and 13, and the clamp is closed.

Figure 5 (F) shows the state at the end of the second bond. When the wedge 8 moves upward with the clamp closed, the wire 9 is cut. Immediately after the wire 9 is cut, the pulse motor 11 to rotate the drive roller 12,
The wire 9 sandwiched between the drive roller 12 and the pressure roller 13 is sent out according to its rotation angle. The tip of this wire 9 is supplied to the tip of the wedge 8 in preparation for the next bonding.

[Detailed description of the invention]

As explained above, the present invention uses a piezoelectric element with a fast response (on the order of μsec) for opening and closing the clamp, so it is possible to increase the speed of the operation. The closing operation can be performed with In addition, since a pair of rollers is used for wire feeding, and the rollers are rotated by direct drive of a pulse motor, the structure is simple and the operation steps of the clamp itself are reduced, improving reliability. can.

[Brief explanation of drawings]

FIG. 1 is a front view of the head according to the present invention, FIG. 2 is a side view thereof, FIG. 3 is a bottom view thereof, FIG. 4 is a perspective view of the head according to the present invention mounted on a stage, and FIG. 5 (a) to (f) are diagrams showing the bonding operation when the head according to the present invention is used, FIG. 6 is a perspective view of the main parts of the conventional head, and FIG. 7 is a diagram showing the conventional head assembled into the stage. It is an explanatory diagram. 7...Horn 9...M wire lO...Piezoelectric displacement element 11...Pulse motor 12
... Drive roller 13 ... Pressure roller 14α, 14
b...Arm 15...Spindle 18...Rotating shaft Patent applicant NEC Corporation Representative Patent attorney Naka Kanno 14 Figure 5 (C)

Claims (1)

[Claims] (1) A drive roller and a pressure roller, which serve as wire clamps, are mounted facing each other on the tips of a pair of arms connected so as to be openable and closable, and a piezoelectric displacement element is installed between the bases of both arms, A head for an ultrasonic wire bonder, characterized in that the rotation axis of the drive roller is linked to a pulse motor.