JPS59181027A - Wire bonding device - Google Patents

Abstract

PURPOSE:To suppress the vibration of a capillary by an eddy current by composing a section integrally operated with a bonding arm of a conductive material and applying a magnetic field to the conductive part. CONSTITUTION:A capillary 4 inserted with a wire is mounted on a bonding arm 5, and the base end of the arm 5 is secured to a bonding arm support 6. In this case, the arm 5 itself or the section operated integrally with the arm 5 is composed of the conductive material, and magnetic field applying means 30 is disposed near the conductive section. Then, when the vibration of the capillary 4 affects adverse influence to the quality of the bonding at wire press-bonding time, wire cutting time or wire ball forming time, the magnetic field is applied to the conduction section, thereby suppressing the vibration of the capillary 4 by the eddy current generated in the conductive section and improving the yield.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a wire nodding device that improves the stability of capillary operation.

[Technical background of the invention and its problems]

In general, a wire ending device used in the assembly process of integrated circuits first presses a capillary into which a wire is inserted against a pad of a semiconductor bullet, which is the first bonding point, for bonding, and then raises the capillary to feed out the wire. Then, the capillary is moved to the lead part of the lead frame, which is the second bonding point, and bonded by lowering it to this lead part and pressing it.Then, by repeating the operation of raising the capillary and cutting the wire, the wiring is disconnected. is configured to do so.

By the way, in such an apparatus, optimizing the load when pressing the capillary against the pellet surface is an important factor in performing bonding with a good yield. However, the capillary generally vibrates when it comes into contact with the pellet surface, and depending on the magnitude of this vibration, an excessive impact load may be applied to the pellet, causing the crimp pole to collapse too much. The above-mentioned vibration increases as the bonding speed increases, and it is not possible to perform bonding with a good yield at high speed with cott.

Therefore, conventional methods have been used to mechanically suppress vibrations by bringing a Dan i4 mechanism using a coil spring or the like into contact with the dending arm (Japanese Patent Application Laid-open No. 57-78147), two electromagnets are placed close to each other,
One electromagnet detects the movement of the binding arm, and current is sent to the other electromagnet according to the movement, and the attraction and repulsion of these two electromagnets is used to prevent vibration of the binding arm (Japanese Patent Laid-Open No. 52-14352) has been proposed.

However, each of these devices has a complicated structure and requires minute mechanical adjustments, minute current detection, etc., making the structure large and expensive, making them unsuitable for practical use.

The present invention reduces capillary vibration with a simple configuration, and
It is an object of the present invention to provide an inexpensive wire bonding device that has high operational stability and can improve yield.

[Summary of the invention]

In order to achieve the above object, the present invention consists of a bonding arm that holds a capillary or a part that operates integrally with the bonding arm, made of a conductive material, and a magnetic field applying means arranged close to this conductive part. A current is generated, and the vibration of the capillary is suppressed by this eddy current.

[Embodiments of the invention]

FIG. 1 is a schematic diagram of a wire bonding apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an XY table, and an XY table 1 is equipped with a tool lifter arm 3 shaped like a letter 1 so as to be swingable in the direction of arrow A on a support column 2. A bending arm 5 having a capillary 4 attached to its tip is arranged below the front arm 3a of the tool lifter arm 3, and the base end of the bonding arm 5 is fixed to a bonding arm supporter 6. ing. This bonding arm supporter 6 is fixed to the intermediate support portion 3C of the tool lifter arm 3 via a leaf spring 7, and between the upper protrusion 6a and the protrusion 3C provided on the front arm 3a of the tool lifter arm 3. A tension spring 8 is tensioned.

Furthermore, a clamp A13 for clamping a wire (not shown) is provided at the tip of the front arm 3a of the sole lifter arm 3. This clamper 13 is used to feed out the wire to the capillary 4, and is opened and closed by a solenoid mechanism (not shown). On the other hand, below the rear arm 3d of the sole lifter arm 3, a glue near motor 9 for swinging and driving the tool lifter arm 3 is disposed. What is this linear motor 9? It operates according to a drive signal output from a linear motor drive circuit 11 in accordance with instructions from a landing control device 10. Further, a position detector 12 is fixed to the tip of the rear arm 3d of the tool lifter arm 3. This position detector 12 detects the position, ie, the swing angle, of the tool lifter arm 3 when the tool lifter arm 3 swings.

In this wire bonding device, first, the XY table 1 is driven under drive control from the bonding control device 10, and thereby the bonding position of the capillary 4 with respect to the bonding object 20 is performed. Then, in accordance with a drive instruction from the bonding control device 10, the linear motor 9 is operated and the sole lifter arm 3 is oscillated, whereby the capillary 4 is lowered and the bonding object 20 is bonded. At this time, the load of the capillary 4 on the bonding object 20 (the pellets are mounted on the lead frame) is applied by the plate spring 7 and the tension spring 8.

By the way, the binding arm 5 is made of a conductive material such as aluminum or stainless steel.
An electromagnet 3o, for example, as shown in FIG. 2, is disposed close to the intermediate portion of the side surface and is supported by a support member 31.

This electromagnet 30 applies a magnetic field to the bonding arm 5 and generates an eddy current in a direction to cancel the vibration of the bonding arm 5.
It operates using the drive current supplied from the controller. This electromagnet drive circuit 33 operates according to instructions from the ending control device 1o.

Next, the operation of the device configured as above will be explained.

First, the movement locus of the capillary 4 during the dending operation changes, for example, as shown in FIG. 3(A). That is, first, the capillary 4 has a semiconductor 4let 20. It descends rapidly toward the dending surface, then switches to low speed just before the surface, and continues the descent to perform crimping. Then, the bonding is finished at point C and it ascends. Then, semiconductor pellet 2
When the bonding to 0th is completed, it moves above the electrode of the lead frame 20b, and then descends to the position d just before the electrode as in the case of the semiconductor pellet 2oa.
After it is temporarily stopped at , it is pressed against the electrode surface between points e and f, and bonding is performed. When this bending is completed, the capillary 4 rises by a certain distance and once stops at a point g, at which point the wire is cut in cooperation with the clan/mother. At this time, a certain length of wire remains at the tip of the capillary, and this wire is used to create a wire gird for the next bonding. When this wire cutting is completed, the capillary 4 rises to the initial position and generates an electric spark at the point to create a wire pole. Thus, the series of bonding operations is completed.

By the way, in the series of bonding operations described above, the position where the vibration of the bonding arm 5 has a large effect on the quality of bonding is b.

Each point is @ + g + h. Therefore, in the device of this embodiment, in order to drive the electromagnet 3o at each of the above points, the bonding control device 1o gives an instruction signal to the electromagnet drive circuit 33, thereby generating a drive current as shown in FIG. 3(B). I have to.

As a result, the electromagnet 30 generates a magnetic field during the drive current generation period, and if vibration is occurring in the dending arm 5 at this time, an eddy current is generated in the dending arm 5 in a direction that cancels out the oscillation. Vibration of the bending arm 5 is suppressed by the magnetic action. This principle is well known as the Arabo disc principle, and a stable braking force proportional to the vibration frequency is generated in the soldering head 5. FIG. 3(c) shows the relative vibration between the tool lifter arm and the denting arm when the electromagnet 30 is driven.

This is the gap sensor 4 at the tip of the tool lifter arm.
You can easily know by setting 0. As is clear from this signal waveform, the vibration of the capillary 4 due to the installation of the electromagnet 30 is significantly smaller than that of the conventional one that does not use an electromagnet (see Figure 3). It was confirmed that the agreement would be finalized.

In this way, in this embodiment, the bonding arm 5
Since a magnetic field is applied to generate eddy current in the direction of canceling vibration, the vibration of the bonding arm 5 can be significantly reduced by the braking action of this eddy current. As a result, even if high-speed bending is performed, it is possible to reduce the crushing of the crimped beer and the impact on circuit elements installed near the electrodes, and to reduce variations in the diameter of the wire beer, resulting in improved yield. This can lead to improvements in productivity. Furthermore, this embodiment has the advantage that the above effects can be achieved with an extremely simple configuration that only includes the electromagnet 30 and its drive circuit 33, and a device with a simple configuration and low cost can be provided.

In addition, in this embodiment, the electromagnet 30 is used as the magnetic field applying means, and this electromagnet 30 is driven only for a necessary period, so that vibrations can be reliably suppressed in the parts that have an important effect on the binding quality. In addition, since no braking action is caused when the capillary is raised or lowered, it is possible to perform the binding action at high speed and with excellent responsiveness.

Note that the present invention is not limited to the above embodiments.

For example, a permanent magnet other than an electromagnet may be used as the magnetic field applying means, and the installation position of the magnetic field applying means is as shown in FIG.
It may be set at a position close to . What about the material of the binding arm and the installation position of the magnetic field application means? The configuration of the landing bed and the like can also be modified in various ways without departing from the spirit of the invention.

〔Effect of the invention〕

As described above in detail, the present invention comprises a dending arm that holds a capillary or a part that operates integrally with the dending arm made of a conductive material, and a magnetic field applying means placed close to this conductive part to suppress eddy current. The eddy current is generated and suppresses the vibration of the capillary.

Therefore, according to the present invention, it is possible to provide an inexpensive wire bonding device that has a simple structure, reduces capillary vibration, has high operational stability, and can improve yield.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a wire bonding device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the main parts of the device, and FIG. 3 is used to explain the operation of the device shown in FIG. 1. FIG. 4 is a perspective view showing the main parts of a wire ending device in another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... XY table, 2... Support column, 3... Tool lifter arm, 4... Capillary, 5... Dending arm, 6... Bonding arm holder, 7
... Leaf spring, 8... Tension spring, 9... Linear motor, 30... Electromagnet, 33... Electromagnet drive circuit.

Claims (2)

[Claims] (1) In a wire ending device that performs wire ending by holding a capillary through which a wire is inserted by a ending arm and moving it up and down to bring it into contact with a rejoining surface, the bonding arm or this ending arm 1. A wire bonding device comprising: a part that operates integrally with the conductive part made of a conductive material; and a magnetic field applying means for generating an eddy current in the conductive part. (2) The wire according to claim 1, wherein the magnetic field applying means comprises an electromagnet, and the electromagnet is driven only during a necessary period during the bonding operation to generate eddy current in the conductive portion. Dending device.