JPH05291337A - Clamp mechanism and wire bonding device with it - Google Patents

Abstract

PURPOSE:To provide a clamp mechanism which has a simple maintenance work for maintaining wire gripping state with a clamp member and can suppress wire damage to the minimum and a wire bonding device with it. CONSTITUTION:By forming the engagement part of a pair of clamp members 8a1 and 8a2 for gripping a wire which a clamp mechanism has with each wire 9 using each different material, buffer operation is activated on either one of engagement parts with a smaller hardness, thus eliminating the need for chamfering operation of both clamp members 8a1 and 8a2 and at the same time minimizing wire damage.

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) as a component to be bonded and a lead, and more particularly to a clamp mechanism for cutting the wire. Regarding The present invention also relates to the clamp mechanism itself to be equipped in the wire bonding apparatus.

[0002]

2. Description of the Related Art Conventionally, in order to perform a bonding connection between a pad of an IC chip and a lead by using this type of wire bonding apparatus, the wire is attached by a capillary as a bonding tool provided at the tip of a bonding arm. The wire is held, brought into contact with the surface of the target pad or lead, and a part of the wire having a ball formed at the tip thereof is crushed using the capillary and thermocompression-bonded to be welded. At this time, ultrasonic vibration may be applied to the tip of the wire at the same time.

The process of performing this wire bonding is shown in FIG.
In the following, the capillaries 7 through which the wires 9 each having a ball formed at the tip thereof are inserted when wire bonding to the pads (electrodes) on the IC chip 25 mounted on the bonding stage 26 are shown. After positioning by moving an XY table (not shown) on the basis of information from an imaging device or the like, the capillary 7 is lowered as shown in FIG. 6 to crush the ball to the pad to perform thermocompression bonding. .

In this step, → moves the bonding arm (not shown) downward at high speed, and → moves it at low speed. At this time, the clamp 8f is open.
Next, when the connection to this first bonding point is completed,
In →, the bonding arm is lifted in the upward direction shown in FIG. 6, that is, in the Z-axis direction while the clamp 8f is in the open state, and the wire 9 is pulled out with the clamp 8f in the open state as shown in accordance with a predetermined loop control. Is connected to the lead 27 which is the second bonding point.

After this connection, the clamp 8f is closed while the wire 9 is pulled out from the tip of the capillary 7 by a predetermined feed amount f as shown by. In this state, the wire 9 is cut as shown in the process of further raising the bonding arm 1 to a predetermined height, and a ball is formed again at the tip of the wire by using an electric torch (not shown), and the clamp 8f is fixed. Return to the open state. Wire bonding is performed by such a series of steps.

Next, the structure of the clamp 8f will be described in detail. As is particularly clear from FIG. 7, the clamp 8f is
It comprises a pair of clamp members 8f ₁ which are provided so as to be openable and closable relative to each other and hold the wire 9. The clamp members 8f ₁ and 8f ₂ are opened and closed by being driven by a driving means (not shown). The drive means and both clamp members 8f ₁ and 8f ₂ are collectively referred to as a clamp mechanism. Both of the clamp members 8f ₁ and 8f ₂ are formed as mirror surfaces so that the surfaces facing each other hold the wire 9, and a cermet (cerm) having excellent wear resistance and corrosion resistance.
et) etc. as a material.

[0007]

However, in such a conventional device, both clamp members 8f ₁ and 8f _{2 are used.}
In order to ensure that the wire 9 is always gripped by means of, there is a drawback in that the so-called surfacing work, in which the parallelism between the facing surfaces of the two clamp members is set with high accuracy, must be performed relatively frequently. , Giving the operator a troublesome feeling. In addition, the wire 9 made of gold, aluminum or the like is used as a clamp member 8f _{1 made} of cermet or the like,
Since it is gripped by 8f _2, there is a drawback that the wire 9 may be damaged and the optimum clamping force may not be obtained.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the prior art, and the maintenance work for maintaining the state of gripping the wire by the clamp member is simple, and the damage of the wire can be minimized. And a wire bonding apparatus including the same.

[0009]

SUMMARY OF THE INVENTION The present invention provides a clamp mechanism including a pair of clamp members for relatively openable and closable gripping a wire, and drive means for opening and closing the clamp members. Each of them is configured such that at least the engaging portion with the wire is made of a different material. Further, the present invention provides a wire bonding apparatus having a bonding tool attached to a tip of a bonding arm and a clamp mechanism for gripping a wire, wherein the clamp mechanism is configured to relatively open and close to grip the wire. It is configured by a pair of clamp members and a drive means for opening and closing the clamp members, and each of the clamp members is configured such that at least engaging portions with the wires are made of different materials.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a wire bonding apparatus according to the present invention will be described with reference to the accompanying drawings. In the following description, the same reference numerals are used for the same or corresponding members as the constituent members of the conventional device shown in FIGS. 6 and 7.

FIG. 1 shows a main part of a wire bonding apparatus according to the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

In this wire bonding apparatus, as shown in FIG. 1, a bonding arm 1 composed of a holding frame 1a and a horn 1b is swingable together with a swing arm 2 around an axial center of a support shaft 3. 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. The support shaft 3 is mounted on an XY table or the like (not shown). An ultrasonic transducer (not shown) for vibrating the horn 1b is incorporated in the holding frame 1a. A solenoid 4a and an electromagnetic attraction piece 4b are fixed to the swing arm 2 and the holding frame 1a so as to face each other. When swinging the bonding arm 1, a power source (not shown) for the solenoid 4a is provided. The bonding arm 1 and the swing arm 2 are fixedly coupled to each other by energizing them from above to generate an attractive force between them and the electromagnetic attracting piece 4b, but shaking so as not to be attracted for a predetermined distance or more. An adjustable stopper 6 fixed to the moving arm 2 with a screw or the like is provided. Further, the swing arm 2 and the holding frame 1
The magnet 5a is located at a position in front of the electromagnetic attraction means.
And the coil 5b are attached respectively. The magnet 5a and the coil 5b constitute means for generating an attraction force for urging the tip of the bonding arm 1, that is, the portion holding the capillary 7 as a bonding tool, in the downward direction in FIG. 2 during bonding. .

A clamp arm 8 is provided at the tip of the swing arm 2, and the clamp arm 8 has a clamp opening / closing mechanism as a driving means composed of a solenoid and a spring as shown in FIG. 81 and a clamp 8a driven by the clamp opening / closing mechanism 81. The clamp 8a is for gripping and cutting the wire 9.

As shown in FIG. 3, a clamp opening / closing mechanism 81 is provided.
Has clamp fixing portions 81b ₁ and 81b ₂ attached and fixed to the clamp arm 8, and the clamp 8a is attached to each tip of these clamp fixing portions 81b ₁ and 81b ₂ . The clamp 8a comprises a pair of clamp members 8a _1, 8a _2, the both clamp members 8a _1, 8
a ₂ has a structure that can be opened and closed in the directions of the arrows,
These clamp portions 8a ₁ and 8a ₂ are configured to be opened and closed by moving an arm 81a that is rotatably fixed about a shaft 81c in the direction of the arrow. This arm 81a is driven by a solenoid (not shown).

Further, as shown in FIG. 1, an electric torch 10 is disposed below the capillary 7 on a vertical shaft (not shown) so as to be rotatable by the action of an actuator or the like, and as the bonding arm 1 moves. It is configured to be rotatable around the capillary 7. This electric torch 10 applies a predetermined voltage to form a ball at the tip of the wire 9.
Further, above the clamp 8a, fixedly supported by a frame (not shown), a predetermined tension is applied to the wire 9 so that the wire 9 is always held straight up to the tip of the capillary 7 of the bonding arm 1. A tension clamp 11 that can be opened and closed by an opening and closing mechanism (not shown) is provided.
The wire 9 is further wound around a spool 36 via a guide 12.

Next, as shown in FIG. 2, the swing arm 2
A support shaft 15a is provided on the rear end side, and the arm side cam follower 15 and the swing base 16a are connected to the support shaft 15a.
It is rotatable around a. A bearing guide 16b is fixed to the swing base 16a at one end, and the preload arm 16 is attached to the other end of the bearing guide 16b.
d is rotatably attached via a support pin 16c. A support shaft 17a is provided at a free end of the preload arm 16d, and a cam follower 17 is rotatably attached to the support shaft 17a. And this preload arm 1
A preload spring 16e, which is a tension spring, is bridged between the tip of 6d and the tip of the swing base 16a, and the arm-side cam follower 15 and the cam follower 17 are the outer peripheral surface of the cam 18 formed in a substantially heart shape. Pressed against the cam surface. The two contact points of the arm side cam follower 15 and the cam follower 17 with respect to the cam 18 are located with the center of rotation of the cam 18 in between.

A frame structure is formed by the swing base 16a, the bearing guide 16b, and the preload arm 16d, which is generically referred to as a swing frame 16. Bearing guide 1 as a constituent member of the swing frame 16
6b is in contact with the outer ring of the radial bearing 20 attached to the cam shaft 19 to which the cam 18 is fitted. The cam 18 is rotated by the torque applied to the cam shaft 19 by the motor 21. The height position of the capillary 7 as a bonding tool is detected by a rotary encoder (not shown) connected to the support shaft 3.

FIG. 4 is an enlarged view of the above-mentioned clamp 8a. The clamp members 8a ₁ and 8a ₂ which are the constituent members of the clamp 8a will be described in detail with reference to the drawing.

In FIG. 4, one clamp member 8a ₂
Is formed, for example, in the shape of a rectangular plate, and is made of a cermet or the like that has conductivity, and is excellent in wear resistance and corrosion resistance. In contrast, the other clamp member 8a _1, the above shape as a whole clamping member 8a ₂
Is formed in the same manner as, for example, and the base portion 8a ₁ b having a relatively large rigidity cermet, rubber or synthetic resin having conductivity and a material, the base body 8a ₁ b
Of the wire 9 attached to the surface facing the clamp member 8a _{2 of}
And a contact portion 8a ₁ a that directly contacts with. That is, in the clamp members 8a ₁ and 8a ₂ , the engaging portions with the respective wires 9 are made of different materials. In such a configuration, as shown in FIG. 4, when both clamp members 8a ₁ and 8a ₂ grip a wire 9 made of a gold wire, an aluminum wire or the like, both engaging portions of both clamp members with respect to the wire 9 are held. Of these, the one with the smaller hardness acts as a cushioning material. Note that this buffering effect is remarkable in rubber and synthetic resin having hardness smaller than that of the wire 9, but it can be obtained to some extent even if a material having hardness larger than that of the wire 9 is used.

Since the above-mentioned cushioning action occurs,
It becomes easy to perform the surfacing work in which the parallelism between the engaging surfaces of the clamp members 8a ₁ and 8a ₂ with respect to the wire 9 must be set with high accuracy, and the damage to the wire 9 can be minimized. Optimal clamping force can also be obtained.

By the way, since the discharge current from the torch 10 shown in FIG. 1 is grounded by the clamp opening / closing mechanism 81, both clamp members 8a ₁ and 8a ₂ have conductivity. Therefore, it is possible to make _one of the clamp members 8a ₁ and 8a ₂ conductive without giving conductivity to both.

FIG. 5 shows an enlarged view of the clamp 8b which is the main part of the clamp mechanism as the second embodiment of the present invention.

In the clamp 8b shown in FIG. 5, one clamp member 8b ₂ is made of cermet or the like, and the other clamp member 8b ₁ is made of rubber or synthetic resin. The clamp member 8b ₁ is a clamp member 8b.
A material of relatively high hardness is used in order to have the required rigidity necessary to grip the wire 9 together with ₂ and make its cut. Thus, even when the entire _one clamp member 8b ₁ of the clamp 8b is configured as described above, as with the clamp 8a shown in FIG. The effect can also be obtained.

In each of the above embodiments, the wire 9
The material of the engaging portion of the pair of clamp members provided for gripping the wire, one of which is a cermet,
Although the other is made of rubber or synthetic resin, other materials such as rubber or synthetic resin may be used, and the material of each engaging portion may be appropriately selected according to the material and diameter of the wire to be handled. . Further, as in the present embodiment, in the case of grounding via the clamp opening / closing mechanism, it is necessary to make at least one of both clamp members conductive.

Further, the contact portion 8a ₁ a in the first embodiment
And, as the material of the clamp member 8b ₁ in the second embodiment, when the code seal <Soft> (registered trademark) sold by Nippon Bulker Industry Co., Ltd. was used, the above effects were obtained.

[0026]

As described above, according to the present invention,
Since the engaging portions of the pair of clamp members for grasping the wire included in the clamping mechanism with the wires are formed of different materials, the one of the engaging portions having the smaller hardness is buffered. Act. Therefore, it is not necessary to carry out a surfacing work for setting the parallelism between the engaging surfaces of the two clamp members with respect to the wire with high accuracy, and the maintenance work for maintaining the wire gripped state by the clamp members is simple. is there. Further, such a cushioning effect has an effect that damage to the wire can be minimized.

[Brief description of drawings]

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

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

FIG. 3 is a perspective view of a clamp mechanism as a first embodiment included in the wire bonding apparatus shown in FIG.

4 is a perspective view showing a state in which a clamp member included in the clamp mechanism shown in FIG. 3 holds a wire.

FIG. 5 is a perspective view showing a state in which a clamp member included in a clamp mechanism as a second embodiment of the present invention grips a wire.

FIG. 6 is an explanatory diagram showing a bonding process of a conventional wire bonding apparatus.

FIG. 7 is a perspective view showing a state in which a clamp member included in a clamp mechanism provided in the wire bonding apparatus shown in FIG. 6 holds a wire.

[Explanation of sign]

1 bonding arm 7 capillary (bonding tool) 8 clamp arm 8a ₁ , 8a ₂ , 8b ₁ , 8b ₂ clamp member 9 wire 10 electric torch 81 clamp opening / closing mechanism (driving means)

Claims (3)

[Claims] 1. A clamp mechanism including a pair of clamp members that are relatively openable and closable to hold a wire, and a drive unit that opens and closes the clamp member, wherein each of the clamp members is at least the wire. A clamping mechanism, characterized in that the engaging portions with are made of different materials. 2. The clamp member according to claim 1, wherein at least one of the clamp members has conductivity.
The described clamp mechanism. 3. A wire bonding apparatus having a bonding tool attached to the tip of a bonding arm and a clamp mechanism for gripping a wire, wherein the clamp mechanism holds the wire so as to be relatively openable and closable. A pair of clamp members and a driving means for opening and closing the clamp members, and each of the clamp members is made of a material in which at least an engaging portion with the wire is different from each other.