JPH06151498A - Wire bonding device - Google Patents

Abstract

PURPOSE:To provide a wire bonding device which can elongate the service life of its bearing and, at the same time, can stably perform bonding. CONSTITUTION:The backlash between the outer and inner rings of a radial bearing supporting the bonding arm 1 of the title device is controlled not by pressurization, but by the strong rigidity of a tabular spring member 17 in its width direction. As a result, the service life of the bearing can be prolonged and the bonding arm can be maintained in such a state that the arm can excellently perform bonding for a long period. At the same time, the need of periodically performing troublesome pressurization adjusting work can be eliminated. In addition, since the spring member 17 exerts a buffering action when a bonding tool 20 is brought into contact with an object to be bonded, the generation of vibrations can be reduced when the tool 20 collides with the object to be bonded and bonding can be performed stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding apparatus for connecting wires by connecting wires between a semiconductor component (IC chip) and leads.

[0002]

2. Description of the Related Art Conventionally, when a pad and a lead of an IC chip are bonded by using this type of wire bonding apparatus, the wire is held by a bonding tool provided at the tip of a bonding arm, and the tip of the wire is held. The part is melted to form a ball, and the ball is brought into contact with the surface of the pad or the lead as an object and crushed to perform thermocompression bonding. At this time, ultrasonic vibration may be applied to the tip of the wire at the same time.

A conventional example of such a wire bonding apparatus is shown in FIG. As shown in FIG. 5, the ultrasonic transducer 50 is
Frame 51 placed on an XY table (not shown)
It is swingably supported above the bracket 51a and the support shaft 52.

A horn 54 having a capillary 53 as a bonding tool at its tip is attached to one end of the ultrasonic transducer 50, and the roller 5 is provided at the tip of the other end.
The lever 57 provided with 6 is fixed. A bonding arm is constituted by these. A cam 58 is provided corresponding to the roller 56, and the lever 57
Is biased counterclockwise in the figure by a coil spring 59 so that the roller 56 contacts the cam 58.

A reel 61 around which a wire 60 is wound is arranged above the ultrasonic transducer 50, and a clamper 62 for holding the wire 60 supplied from the reel 61 is provided in the front. . A torch 63 for melting the tip portion of the wire 60 to form a ball is provided near the capillary 53, and is rotatable about a vertical shaft 64. . Further, a position detecting device 65 including a camera or the like is provided above the capillary 53, and the position detecting device calculates a deviation amount of the IC chip 67, which is an object to be bonded, from a reference position to perform normal bonding. Ask for points. Then, based on the obtained values, the XY table is moved to perform bonding.

When a bonding operation is performed by the apparatus having the above-mentioned structure, the cam 58 is rotationally driven by a pulse motor (not shown) or the like, whereby the bonding arm is swung in accordance with the shape of the cam 58 to move the capillary 53 up and down. Make a bonding connection. In addition, the formation of balls at the tip of the wire during the bonding operation,
Contacting and crushing the ball to the pad and lead,
Since various detailed operations such as cutting of the wire are disclosed in, for example, Japanese Utility Model Publication No. 63-48123, the detailed description thereof will be omitted here.

The approaching and separating operations of the capillary 53 with respect to the IC chip 67 are carried out by swinging the ultrasonic transducer 50 and the bonding arm such as the horn 54 around the support shaft 52. 6 shows. Note that FIG. 6 shows a DD cross section relating to FIG.

As shown in FIG. 6, the support shaft 52 for supporting the ultrasonic transducer 50 and the horn 54 is composed of the frame 5
One end (shown in FIG. 5) of the pair of brackets 51a incorporated in the pair of brackets 51a is held by the radial bearings 69 to be swingable. Then, in order to prevent rattling of the inner and outer rings of the radial bearing 69 in the thrust direction, the pressurizing plate 7 is applied to the inner ring of the radial bearing 69 and the support shaft 52 by the compression spring 70.
Pressurization in this direction is given via 1.

[0009]

In the wire bonding apparatus having the above structure, the radial bearing 69 is used.
Since the thrust force is applied to the bearing, the life of the bearing is short, and it is difficult to maintain a good bonding condition for a long period of time, and the pressure must be adjusted periodically. There is.

In addition, since the capillary 53 approaches the IC chip 67 at a relatively high speed during bonding, the capillary 53 collides with the IC chip, albeit slightly.
If the vibration generated by this collision overlaps with the other vibration applied for bonding, there is a disadvantage that the bonding is adversely affected to some extent.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a wire bonding apparatus capable of achieving a long bearing life and stable bonding. There is.

[0012]

According to the present invention, a bonding arm holding a bonding tool is swingably supported by a supporting mechanism via a radial bearing, and the wire is brought into contact with or separated from the object to be bonded. In the bonding apparatus, a spring member formed in a substantially plate shape is attached to the support mechanism at one end so that its flexible direction substantially matches the swinging direction of the bonding arm, and the other end of the spring member is attached. It is configured to be coupled to the bonding arm.

[0013]

Embodiments of the wire bonding apparatus according to the present invention will now be described with reference to the drawings. Since this wire bonding apparatus is configured in substantially the same manner as the conventional apparatus shown in FIG. 5 except for the portions described below, description of the entire apparatus will be omitted.

As shown in FIG. 1, the bonding arm 1 consisting of the holding frame 1a and the horn 1b is swingable around the axial center of the support shaft 3 together with the swing arm 2. More specifically, as is clear from FIG. 3, the holding frame 1a forming a part of the bonding arm 1 is firmly fitted to the support shaft 3, and the swing arm 2 is swingably fitted to the support shaft 3. . An ultrasonic transducer (not shown) for vibrating the horn 1b is incorporated in the holding frame 1a. As shown in FIG. 1, the swing arm 2 and the holding frame 1a have a solenoid 4a and an electromagnetic attraction piece 4b, respectively.
Are fixed in correspondence with each other, and when swinging the bonding arm 1, a solenoid 4a is energized from a power source (not shown) to generate an attractive force between the solenoid 4a and the electromagnetic attraction piece 4b. As a result, the bonding arm 1 and the swing arm 2 are fixed to each other and coupled. A magnet 5a and a coil 5b are attached to the swing arm 2 and the holding frame 1a in front of the electromagnetic attraction means. The magnet 5a and the coil 5b are
It constitutes a means for generating a suction force for urging the tip of the bonding arm 1 at the time of bonding, that is, the portion holding the capillary 20 as a bonding tool downward in FIG.

As shown in FIG. 2, a support shaft 6a is provided on the rear end side of the swing arm 2, and the arm side cam follower 6 and the swing base 9a are rotatable around the support shaft 6a. Has become. A bearing guide 9b is fixed at one end to the swing base 9a.
A preload arm 9d is rotatably attached to the other end of b via a support pin 9e. A support shaft 7a is provided at a free end of the preload arm 9d, and a cam follower 7 is rotatably attached to the support shaft 7a. And
A preload spring 9f, which is a tension spring, is bridged between the tip of the preload arm 9d and the tip of the swing base 9a, and the arm side cam followers 6 and 7 follow the outer circumference of a cam 8 formed in a substantially heart shape. It is pressed against the cam surface which is the surface. The two contact points of the arm side cam follower 6 and the cam follower 7 with respect to the cam 8 are located with the center of rotation of the cam 8 in between.

A frame structure is formed by the rocking base 9a, the bearing guide 9b, and the preload arm 9d, and is collectively referred to as a rocking frame 9. A bearing guide 9b as a component of the swing frame 9 is in contact with an outer ring of a radial bearing 11 attached to a cam shaft 12 fitted with a cam 8. The cam 8 is
The motor 13 rotates by the torque applied to the cam shaft 12.

Here, the structure for swingably supporting the above-mentioned bonding arm 1 will be described in detail with reference to FIG.

As shown in FIG. 3, a pair of left and right bracket portions 15a is provided on a frame 15 which constitutes a part of a support mechanism (not shown as a whole), and radial bearings are provided in the respective bracket portions 15a. 16 are installed. The support shaft 3 carrying the holding frame 1a, which is a constituent member of the bonding arm 1, is fitted to the inner rings of these radial bearings 16. This allows the bonding arm 1 to swing.

As shown in FIG. 3, the frame 15 described above is used.
Another bracket portion 15b is provided at a position sandwiched by the bracket portions 15a. As shown in FIGS. 1 and 4, at the upper end of the bracket portion 15b,
One end of the spring member 17 formed in a flat plate has a machine screw 18
(Reference numerals are shown only in FIG. 4).
The other end of the spring member 17 is fixed to the holding frame 1a with a machine screw 19 (see FIG. 4).
The spring member 17 is also shown in FIG.

The above-mentioned spring member 17 is arranged so that its flexible direction coincides with the swinging direction of the bonding arm 1. Further, as is particularly clear from FIG. 4, both ends of the spring member 17 are connected to the bracket portion 15b and the holding frame 1a, respectively, and the spring member 17 is bent at the center thereof. Then, as shown in the figure, this bending center is aligned with the axial center of the support shaft 3.

By arranging the flat plate-shaped spring member 17 as described above, it is possible to prevent the play in the thrust direction of the inner and outer rings of the radial bearing 16 shown in FIG.
7 can be regulated with a large rigidity in the width direction, and it is not necessary to apply a special pressurization to prevent rattling.

Further, the spring member 17 is provided so that the amount of bending increases as the capillary 20 (see FIG. 1) approaches the object to be bonded. Specifically, as shown by the chain double-dashed line in FIG. 4, when the bonding arm 1 holding the capillary 20 is in the raised position, the spring member 17 is in a completely flat plate state with its deflection amount being zero, As the bonding arm 1 swings downward, it gradually bends. With such a configuration, when the capillary 20 comes into contact with the object to be bonded during bonding, the spring member 17 has a cushioning effect, and the occurrence of vibration due to the capillary 20 colliding with the object to be bonded at a relatively high speed is avoided. It In addition, in FIG. 4, reference numeral θ indicates a swing stroke of the bonding arm 1.

Next, an outline of the operation of the wire bonding apparatus having the above structure will be described according to the procedure of the bonding work.

First, a bonding stage (not shown)
Above the IC chip placed on top, the capillary 20
Is positioned by operating an XY table (not shown) based on the information from the position detection device (65: see FIG. 5). With this positioning, the cam 8 and the motor 1
The bonding arm 1 is swung downward by the arm driving means composed of 3 or the like to lower the capillary 20,
The ball is crushed against the pad of the IC chip, which is the bonding point, to perform thermocompression bonding. After this bonding connection, a wire is connected to the lead serving as the second bonding point, and a series of bonding operations are performed.
The above-described bonding work is performed on the pads and leads on all IC chips, and the same work is repeated for the next IC chip and leads.

[0025]

As described above, according to the present invention,
Rattling of the inner and outer rings of the radial bearing that supports the bonding arm can be regulated with great rigidity in the width direction of the plate-shaped spring member regardless of pressurization, so that the life of the bearing can be extended and bonding can be performed. There is an effect that a good condition can be maintained for a long period of time and it is not necessary to periodically perform a complicated pressurizing adjustment work. Further, since the spring member acts as a buffer when the bonding tool comes into contact with the object to be bonded during bonding, occurrence of vibration due to the collision of the bonding tool with the object to be bonded is avoided, and stable bonding is performed. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a side view including a partial cross section of a main part of a wire bonding apparatus according to the present invention.

2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB in FIG.

FIG. 4 is an enlarged view of a portion C in FIG.

FIG. 5 is a side view of a conventional wire bonding apparatus.

6 is a sectional view taken along line DD of FIG.

[Explanation of sign]

 1 Bonding arm 3 Support shaft 16 Radial bearing 17 Spring member

Claims (2)

[Claims] 1. A wire bonding method in which a bonding arm holding a bonding tool is swingably supported by a support mechanism via a radial bearing, and the swinging of the bonding arm causes the bonding tool to move toward and away from a bonding target. In the device, a spring member formed in a substantially plate shape is attached to the support mechanism at one end so that its flexible direction substantially matches the swinging direction of the bonding arm, and the other end of the spring member is attached. A wire bonding apparatus, wherein the wire bonding device is connected to the bonding arm. 2. The wire bonding apparatus according to claim 1, wherein the spring member is provided so that a bending amount thereof increases as the bonding tool approaches an object to be bonded.