JPS62179733A - Wire bonding system - Google Patents

Abstract

PURPOSE:To automatically form a ball at the end of a wire by raising the wire in a predetermined height when the wire is not projected in a necessary length, then opening an upper clamper, closing a lower clamper and projecting the wire in the necessary length while moving down the lower clamper slightly. CONSTITUTION:When a wire is broken, an upper clamp 14 is immediately closed, a lower clamp 15 is simultaneously opened, and the wire is driven by a linear motor 4 in the state that an electromagnet 17 is energized, i.e., in the state the holder 6 of a bonding horn 6 and a bonding driving arm 3 are fixed integrally to be raised in a predetermined length L. The end of the wire 8 is fed in the length L from a capillary 9, the clamp 14 is opened, the clamp 15 is simultaneously closed, and the clamp 15 is moved down slightly N times. When the end of the wire 8 does not arrive at a spark gap level, no spark is generated. Accordingly, it is electrically detected, and the operation is again repeated. When the wire arrives at the spark gap level, a discharge is generated to a torch rod 25 to form a ball 26 at the end of the wire 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a wire bonding device that connects, for example, a pad electrode of a semiconductor pellet to a lead end using a wire.

[Technical background of the invention and its problems]

Conventionally, this type of wire bonding equipment.

It is known that a bonding horn having a bonding capillary (bonding tool) at its tip is moved up and down in a predetermined bonding cycle. In this bonding cycle, before moving the bonding capillary to the first bonding point (the electrode of the pellet), the tip of the wire that has been let out from the tip of the capillary is melted using an electric torch or the like to form a ball. . Also, after bonding the tip of the wire to the electrode of the pellet, the wire is fed out and guided to the second bonding lead end), and at the same time as bonding,
The wire is cut at the bonding location. Then, a transition is made to the ninth bonding cycle.

However, in the above bonding process.

Although the wire is typically cut at the second bonding point, the wire may be cut at other locations. For example, it may break midway inside the capillary or midway through the delivery before reaching the capillary.

In such a case, the subsequent operation will not be performed normally, so the wire bonding device automatically stops its operation and an alarm is sounded. The operator then opened each clamper, pulled out the wire using a bin set, and used an electric torch to protrude it from the tip of the capillary.

I'm trying to create a ball.

In other words, since these operations are performed manually, they are troublesome and time-consuming, and there are drawbacks such as a significant drop in the operating rate of the machine.

[Purpose of the invention]

The present invention has been made by paying attention to the above-mentioned circumstances.

The purpose is to provide a wire bonding method that can automatically feed out the wire when it does not pay out normally from the tip of the bonding tool, and can automatically form a ball at the tip. .

[Summary of the invention]

To achieve the above object, the present invention provides a wire bonding method in which a connecting wire is led to a wire bonding tool through an upper clamper and a lower clamper, and a ball is formed at the tip of the wire fed out from the wire bonding tool. When the length of wire necessary to form a ball does not protrude from the feeding end of the wire bonding tool, the wire bonding tool is stopped, the upper clamper is closed, the lower clamper is opened, and the lower clamper is raised to a predetermined height. After this, the upper clamper is opened, the lower clamper is closed, and the lower clamper is lowered several times in small increments while protruding the wire by the length necessary for forming the ball from the feeding end of the wire bonding tool to form the ball. It is a wire bonding method.

[Embodiments of the invention]

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

FIG. 1 shows a wire bonding device Ill, and numeral 1 in the figure is a head frame, and this head frame 1 is moved in the horizontal direction by an XY table (not shown). A bonding drive arm 3 is pivotally attached to the head frame 1 via a shaft 2. This bonding drive arm 3 is configured to be swung vertically by a linear motor 4. Also.

In this embodiment, a holder 6 for an ultrasonic horn 5 for bonding, which constitutes a bonding head, is connected to the bonding drive arm 3 via a leaf spring 7, and the ultrasonic horn 5 is driven to swing in the vertical direction. It is now possible to do so.

At the tip of the bonding ultrasonic horn 5.

A capillary 9 is attached as a wire bonding tool through which a thin metal wire for connection, such as a wire 8 made of gold, is inserted. The wire 8 inserted into the capillary 9 is led out from a spool 11 attached to the head frame 1.

The wire 8 passes through a wire clamper 12, is guided by a wire guide plate 13, and is led to the capillary 9 through an upper clamper 14 and a lower clamper 15 in sequence.

The wire clamper 12 and wire guide plate 13 are as follows.

Each of them is fixedly provided to the head frame 1. Further, the upper clamper 14 is also fixedly provided to the head frame 1 via a support arm 16. However, the lower clamper 15 is attached to the bonding drive arm 3.

The bonding drive arm 3 and the bonder 6 Between the ink ultrasonic horn 5 and the holder 6.

An electromagnet 17 is installed to selectively fix both of them. As shown in FIG. 1, this electromagnet 17 has an iron core 19 and an electromagnetic coil 20 fixedly attached to it via a bracket 18a attached to the bonding driving arm 3, and also serves as a holder for the bonding ultrasonic horn 5. An arm 21 integrally extending from the iron core 19 extends to a position facing the magnetic pole of the iron core 19, and a suction plate 22 is attached to this extended portion. The iron core 19 and this suction plate 22 are.

It is made of ferromagnetic material such as iron.

Further, between the tip of the bracket 18 attached to the bonding driving arm 3 and the tip of the arm 21 that integrally extends from the holder 6 of the bonding ultrasonic horn 5, a tension coil is provided as a biasing member. A spring 23 is installed. That is, one end of this tension coil spring 23 is fixedly attached directly to the tip of the arm 21, and the other end of the tension coil spring 23 is attached to a hook 24 screwed onto the tip of the bracket 18. It is worn.

The tension coil spring 23 connects the bonding drive arm 3 and the holder 6 of the bonding ultrasonic horn 5 with a predetermined force using its tension biasing force.

Further, a torch rod 25 is provided at the lower part of the capillary 9.
can be selectively inserted.

On the other hand, the linear motor 4 and the electromagnet 17. Furthermore, the XY table (not shown) is connected to a microcomputer (not shown).
The drive is controlled by a controller such as CPLI).

Next, the operation of the wire bonding apparatus will be explained.

First, the wire 8 paid out from the spool 11 passes through the wire clamper 12 and is guided by the wire guide plate 13, then passes through the upper clamper 14 and the lower clamper 15 in order, and its tip is guided to the capillary 9. It protrudes from the tip of the capillary 9. Before the start of the wire bonding cycle, the protruding tip of the wire 8 is melted by the torch rod 25 to form a ball 26 in advance.

Therefore, when the bonding cycle starts, the bonding drive arm 3 is oscillated by the linear motor 4, but at this time, the 'RN magnet 17 is energized, so the electromagnet 17 attracts it.

This is because the holder 6 of the bonding horn 5 and its bonding drive arm 3 are integrated.

These swing together. At first, this rocking speed is fast;
The capillary 9 descends at high speed and then reaches the first bonding position while decelerating to a constant speed. At this time,
Because the electromagnet 17 is deenergized.

The holder 6 of the bonding horn 5 and its bonding drive arm 3 are connected by the biasing force of a tension coil spring 23. Thereafter, the first bonding is performed by the biasing force of the tension coil spring 23. After this bonding operation.

The electromagnet 17 is energized again, and the holder 6 of the bonding horn 5 and its bonding drive arm 3 are connected, and while these are raised, the head frame 9 is moved by the XY table, and the capillary is moved in the same manner as in the above operation. 9 is lowered at high speed and then positioned at the second bonding position while decelerating to a constant speed.

Furthermore, since the electromagnet 17 is deenergized after this, the second bonding is performed by the urging force of the tension coil spring 23. After this bonding operation, the electromagnet 17 is energized again.

The holder 6 of the bonding horn 5 and its bonding drive arm 3 are connected together and rise. That is, the N magnet 17 is excited when descending and ascending the capillary 9, engages the holder 6 of the bonding horn 5 and its bonding drive arm 3, and prevents vibration therebetween.

It is deenergized during the first and second bonding operations. During the first and second bonding operations, the urging force of the tension coil spring 23 is transmitted and used as a pressing force.

By the way, the wire 8 may break during the above bonding operation. At this time, the next automatic feeding of the wire 8 and automatic pole forming operations are performed to automatically return to the normal state.

That is, for example, when cutting is performed in the state shown in FIG. 6 and the bonding driving arm 3 are fixed and integral, and are driven by the linear motor 4 and raised by a predetermined amount (L) to the position shown in FIG. 2(b). Therefore, the tip of the wire 8 is connected to the capillary 9 by a predetermined amount (L).
It is brought out from. At this rising end position, the upper clamp 14 opens, and at the same time the lower clamp 15 opens.
is closed, and the lower clamp 15 is lowered N times in small steps from FIG. 2(C) to FIG. 2(e). The descending length 1) at this time is shorter than the predetermined length 1(L). After this first descent, a voltage is applied between the tip of the wire 8 and the torch bar 25 in the state shown in FIG. 2(e). If the tip of the wire 8 does not reach the spark gap level, there will be no spark, so this is electrically detected and the same process [(f) to (h)] as the first time is repeated. When the spark gap level is reached in FIG. 2(h), a discharge occurs between the wire 8 and the torch rod 25, and a ball 26 is formed at the tip of the wire 8, resulting in the state shown in FIG. 2(+).

Here, L=NX+, where N is the number of times the lower clamper 15 (closed) descends, and 1 is the length of descent of the lower clamper 15 (closed), for example, several tens of minus.

In addition, since the second and subsequent processes tend to reach the spark gap level immediately, it is preferable to make the small increments smaller than those in the first process.

A ball 26 is formed at the tip of the wire 8, which is detected by electrical changes during discharge and automatically returns to normal wire bonding cycle operation.

Although the above-mentioned embodiment shows the case of a ball bonding method, the present invention is not limited to this, and can also be applied to, for example, a wedge bonding method in which no balls are formed.

〔Effect of the invention〕

According to the present invention, when the wire is not normally paid out from the tip of the bonding tool, such as when the wire is cut at a place other than the original one, the wire can be automatically fed out and a ball can be automatically formed at the tip. Therefore, since there is no need to perform these operations manually, it is possible to save time and effort, and to greatly improve the operating rate of the machine.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a wire bonding apparatus according to a first embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation cycle of automatic wire feeding and automatic ball formation. 3... Bonding drive arm, 5... Bonding horn, 6... Holder, 8... Wire, 9...
・Capillary, 14...upper clamp, 15...lower clamp. 25...torch stick, 26...ball.

Claims (3)

[Claims] (1) In a wire bonding method in which a connecting wire is led to a wire bonding tool through an upper clamper and a lower clamper, and a ball is formed at the tip of the wire fed out from the wire bonding tool, the ball is formed from the feeding end of the wire bonding tool. When the wire length required to form the wire does not protrude, the wire bonding tool is stopped, the upper clamper is closed, the lower clamper is opened, the lower clamper is raised to a predetermined height, and the upper clamper is then opened. A wire bonding method characterized by forming a ball by closing a lower clamper and lowering the lower clamper in small increments multiple times while protruding the wire by the length necessary for forming the ball from the feeding end of the wire bonding tool. . (2) The wire bonding method according to claim 1, wherein the ball is formed by discharging an electric torch. (3) The wire bonding method according to claim 2, wherein an electric torch during the formation of the ball is installed directly below the wire bonding tool.