JPH08264583A - Wire bonding device - Google Patents

Abstract

PURPOSE: To provide a wire bonding device wherein fused ball for bonding can be formed stably within a short treatment time. CONSTITUTION: This device is comprised of a torch rod 36 which has a torch electrode 36a for forming a fused ball 4 at a tip of a wire by generating discharge between it and a tip of a wire in a forming gas atmosphere by making forming gas 47 flow toward a bonding head 34 which can e moved horizontally, a capillary 35 wherethrough a wire 3 passes and a tip of a wire passing through a capillary and a lead frame carrier device 31 which carries and guides a lead frame 2 whereon a semiconductor pellet 1 is mounted in the forming gas atmosphere. An electrode of a semiconductor pellet and a lead of a lead frame are wire-bonded in the forming gas atmosphere through operation of a bonding head and a capillary.

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, and more particularly to a wire bonding apparatus capable of forming a molten ball at the tip of a wire during wire bonding.

[0002]

2. Description of the Related Art As shown in FIG. 4, in a conventional wire bonding apparatus 10, a lead frame 2 having a semiconductor pellet 1 mounted in a previous step is conveyed by a lead frame conveying apparatus 11 and inserted into a capillary 12. Wire 3
Discharge between the tip of the torch electrode 13a and
The molten ball 4 is formed at the tip of the wire 3, the bonding head 14 and the bonding arm 15 are operated to bond the molten ball 4 to the electrode of the semiconductor pellet 1, and then the wire 3 is bonded to the lead of the lead frame 2. ,
These electrodes are electrically connected to the leads. The torch electrode 13a is the bonding head 14
It is a fixed torch electrode held at the tip of the fixed torch rod 13 fixed to.

In the wire bonding apparatus 10 described above, particularly when the lead frame 2 and the wire 3 are made of a material such as copper which is easily oxidized, the lead frame transporting apparatus 11 has a cover having an opening 28 corresponding to the bonding position. It is surrounded by 27, and the inside thereof is filled with the forming gas 17 supplied from the gas supply pipe 16, and the forming gas 18 is ejected from the torch rod 13 toward the tip of the wire 3 inserted into the capillary 12. . The forming gas 18 prevents the molten ball 4 from being oxidized, and the forming gas 17 prevents the lead frame 2 or the bonded wire 3 from being oxidized.

Further, in some conventional wire bonding apparatuses, as shown in FIG. 5, the torch rod 20 is equipped with a movable torch electrode which swings horizontally with respect to the bonding head 14. With this mobile torch electrode,
The arm 21 is pivotally supported by the block 22.
A torch rod having a torch electrode 20a at its tip is installed at one end of the. Further, an electromagnet 23 is installed in the block 22, and a coil spring 25 that applies a tensile force is arranged at the other end of the arm 21. Therefore, the electromagnet 23
Moves the rod 26 back and forth, so that the coil spring 25
The arm 21 swings in the direction of arrow A due to the interaction with the pulling force of the torch rod 20, and thus the torch rod 20 swings in the same direction, and the torch electrode 20a is shown by the solid line and the position directly below the capillary 12 shown by the chain line. Move to and from the standby position. Then, the torch electrode 20a is positioned directly below the capillary 12, and a discharge is generated between the tip of the wire 3 inserted through the capillary 12 and the torch electrode 20a to form the molten ball 4, and then the torch electrode is formed. 20a is returned to the standby position, the capillary 12 is lowered, and the bonding operation is performed.

[0005]

However, in the conventional wire bonding apparatus 10 shown in FIG. 4, the cover 27 of the lead frame carrying apparatus 11 is formed with an opening 28 that allows the capillary 12 to move vertically and horizontally. Therefore, the forming gas 17 flowing out from the opening 28
However, the forming gas 18 ejected from the torch rod 13
In addition, a collision occurs near the tip of the wire 3 held by the capillary 12, and a turbulent flow is generated. Then, since the discharge between the tip of the wire 3 and the torch electrode 13a is performed in this turbulent flow, the discharge state becomes very unstable, and as a result, the size of the molten ball 4 is not constant. However, it had the drawback of being scattered.

The movable torch electrode 20 shown in FIG.
In the case of a, the torch electrode 2 is formed when the molten ball 4 is formed.
Since 0a moves and is positioned immediately below the capillary 12, the torch electrode 20a blocks the forming gas 17 flowing out from the opening 28 of the lead frame transfer device 11. Therefore, the discharge between the tip of the wire 3 and the torch electrode 20a is performed in the atmosphere of the forming gas 18 having a constant flow, and the molten ball 4 is stably formed. However, in the case of the movable torch electrode 20a, when the torch electrode 20a moves to a position directly below the capillary 12 and stops, the torch electrode 20a vibrates due to the influence of inertia, and discharge occurs until the vibration stops. Cannot be carried out. Therefore, the wire bonding process cannot be performed quickly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wire bonding apparatus capable of stably forming a molten ball without impairing the wire bonding processing time.

[0008]

According to a first aspect of the present invention, there is provided a bonding head which is movable in a horizontal direction, a capillary which is provided on the bonding head so as to be vertically movable through a bonding arm and through which a wire is inserted, and A torch rod that is fixed to a bonding head and flows a forming gas toward the tip of the wire that is inserted into the capillary, and discharges between the tip of the wire and the tip of the wire to form the forming gas. A torch rod having a torch electrode that forms a molten ball at the tip of the wire in the atmosphere of, and a lead that is disposed below the capillary and that conveys and guides the lead frame on which the semiconductor pellets are mounted in the atmosphere of the forming gas. It has a frame transfer device and operates the bonding head and capillaries. Therefore, in the wire bonding device for bonding the electrode of the semiconductor pellet and the lead of the lead frame with the wire in the atmosphere of the forming gas of the lead frame transport device, the torch rod is formed in a tubular shape. A flow path for flowing the forming gas is formed inside, and the torch electrode at the tip of the flow path extends beyond just below the capillary. Furthermore, the torch electrode has the capillary directly below the capillary. An insertion hole that allows insertion is formed.

According to a second aspect of the present invention, the insertion hole formed in the torch electrode according to the first aspect has a tapered shape in which the diameter decreases toward the capillary side.

[0010]

The invention described in claim 1 has the following functions. Since the torch electrode extends just below the capillary, the forming gas flowing out from the lead frame transport device is blocked by the torch electrode and the torch rod supporting it. Therefore, the electric discharge generated between the tip of the wire and the torch rod is performed and stabilized in the atmosphere of the forming gas in which the flow flowing inside the torch rod is stable. As a result, the size of the molten ball formed at the tip of the wire by the above-mentioned electric discharge becomes constant and stabilized.

Further, since the torch electrode is a fixed type torch electrode supported by a torch rod fixed to the bonding head, the wire bonding processing time can be shortened as compared with the movable type torch electrode. That is, in the case of the movable torch electrode, the torch electrode moves to the vicinity of the capillary and stops in order to form a molten ball at the tip of the wire, but at this time, the torch electrode vibrates due to inertia. Therefore, the movable torch electrode must wait for the molten ball forming operation by electric discharge until the vibration of the torch electrode stops.
On the other hand, in the case of the fixed type torch electrode, since there is no movement and stop itself as described above, and vibrations accompanying it do not occur, the molten ball forming operation can be carried out immediately after the completion of the wire bonding operation in the previous step, and therefore the wire The bonding processing time is not impaired.

The invention according to claim 2 has the following effects. Since the insertion hole for inserting a capillary formed in the torch electrode has a tapered shape whose diameter decreases toward the capillary side, the peripheral edge portion of the insertion hole on the capillary side of the torch electrode has a sharp edge shape toward the capillary side. Therefore, discharge can be easily generated between the sharp edge and the tip of the wire.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an embodiment of the wire bonding apparatus according to the present invention with a part thereof broken away. Figure 2
[Fig. 2] is a perspective view showing a tip portion of the torch rod of Fig. 1. FIG.
FIG. 4 is a sectional view showing a discharge state between a torch electrode and a wire.

The wire bonding apparatus 30 shown in FIG.
Is a lead frame transport device 31, an XY table 32,
It has a bonding head 34, a capillary 35, and a torch rod 36. Lead frame carrier 3
1 intermittently conveys and guides the lead frame 2 on which the semiconductor pellet 1 is mounted in the previous step to the bonding position. The XY table 32 is disposed on the side of the lead frame transporting device 31, and is connected to the lead frame transporting device 31.
It is provided so as to be movable in the transport direction and the direction orthogonal to this direction. The bonding head 34 is the XY table 3
2 is provided so as to be horizontally movable and provided with a bonding arm 33 which is vertically swingable by an arm driving mechanism (not shown). The capillary 35 is attached to the tip of the bonding arm 33 so as to be capable of moving up and down, and allows the wire 3 to be inserted therethrough. The torch rod 36 is fixedly supported by the bonding head 34. At the tip of the torch rod 36, there is provided a torch electrode 36a extending just below the capillary 35.
A discharge voltage is applied between a and the tip of the wire 3 inserted through the capillary 35 to generate a discharge, and the molten ball 4 can be formed at the tip of the wire 3.

A spool 37 around which the wire 3 is wound is installed on the bonding head 34. Wire 3
Is guided from this spool 37 to the capillary 35 through a clamper (not shown). The clamper is provided integrally with the bonding arm 33, and after the electrode of the semiconductor pellet 1 and the lead of the lead frame 2 are connected with the wire 3 (described later), the wire 3 is gripped when the bonding arm 33 moves up. Then, the wire 3 is pulled and cut.

Therefore, this wire bonding apparatus 30
Operates as follows. First, when the lead frame 2 on which the semiconductor pellet 1 is mounted is positioned at the bonding position by the lead frame transfer device 31,
Electric discharge is generated between the tip of the wire 3 inserted in the capillary 35 and the torch electrode 36a, and the molten ball 4 is formed at the tip of the wire 3. Next, the bonding arm 3
By the operation of 3, the capillary 35 descends, and the molten ball 4 is bonded to the electrode of the semiconductor pellet 1. After that, the capillary 35 moves directly above the lead of the lead frame 2 while the wire 3 is led out, and the wire 3 is joined to this lead to electrically connect the electrode and the lead. After this connection, the bonding arm 33 rises and the clamper pulls and cuts the wire 3 near the lead. The above-mentioned wire bonding operation is carried out for a single semiconductor pellet 1 between a plurality of electrodes and leads.

Now, the lead frame transfer device 31
The cover 39 covers the upper part of the guide rail 38, and the guide rail 38 guides the conveyance of the lead frame 2 on which the semiconductor pellet 1 is mounted. A gas supply pipe 40 is installed on the guide rail 38, and an internal space of the lead frame transfer device 31 surrounded by the guide rail 38 and the cover 39 is filled with the forming gas 41 supplied from the gas supply pipe 40. Therefore, the lead frame 2 on which the semiconductor pellets 1 are mounted is transferred to the forming gas 4 by the lead frame transfer device 31.
1 is transported in the atmosphere. This forming gas 41
Is composed of an inert gas and prevents the lead frame 2 or the bonded wire 3 from being oxidized during wire bonding.

On the cover 39 of the lead frame transfer device 31, a position corresponding to the bonding position, that is,
The capillary 35 is installed directly above and the heater 42 is installed directly below.
An opening 44 is formed at a position where the bonding stage 43 having the embedded therein is installed. The opening 44 allows the capillary 35 to move between the electrode of the semiconductor pellet 1 and the lead of the lead frame 2 in the lead frame transfer device 31.

On the other hand, the torch rod 36 supporting the fixed torch electrode 36a is formed in a tubular shape, and a gas flow passage 45 is formed inside. The tip of this torch rod 36 is
As shown in FIG. 2, a notch 46 is formed on the side of the capillary 35, and the tip of the wire 3 inserted into the capillary 35 is configured to pass through the notch 46 and reach the gas flow channel 45. The forming gas 47 made of an inert gas flows through the gas flow path 45, and therefore the molten ball 4 can be formed at the tip of the wire 3 in the atmosphere of the forming gas 47. This forming gas 47
This prevents the molten balls 4 from being oxidized.

Further, in the torch electrode 36a provided at the tip portion of the torch rod 36, a capillary insertion hole 48 through which the capillary 35 can be inserted is formed immediately below the movement of the capillary 35. As shown in FIG. 3, the capillary insertion hole 48 is formed in a taper shape in which the diameter becomes smaller toward the capillary 35 side, so that the torch electrode 36 is formed.
The insertion hole peripheral edge portion 49 on the capillary 35 side in a is formed in a sharp edge shape toward the capillary 35 side.

As described above, in the wire bonding apparatus 30, the formation of the molten ball 4 is performed by the torch rod 3
6 is performed in the atmosphere of the forming gas 47 flowing through the gas flow passage 45, and the molten balls 4 are prevented from being oxidized. Further, during wire bonding, the capillary 35 moves up and down through the capillary insertion hole 48 of the torch electrode 36a,
The electrode of the semiconductor pellet 1 and the lead of the lead frame 2 are wire-bonded through the opening 44 of the lead frame carrying device 31 and in the lead frame carrying device 31 filled with the forming gas 41.

According to the above embodiment, the following effects (1) to (4) are obtained. Since the torch electrode 36 a extends directly below the capillary 35, the opening 4 of the lead frame transfer device 31 is opened.
Even if the forming gas 41 flows out from 4 toward the capillary 35, the forming gas 41 is blocked by the torch electrode 36a and the torch rod 36 supporting the torch electrode 36a. Therefore, the tip of the wire 3 and the torch electrode 3
The discharge 50 generated between the discharge gas 6a and 6a is stabilized in the atmosphere of the forming gas 47 in which the flow of the torch rod 36 is stable. As a result, the size of the molten ball 4 formed at the tip of the wire 3 by the discharge 50 is constant and stabilized.

Although a part of the forming gas flowing out from the opening 44 passes through the capillary insertion hole 48 formed in the torch electrode 36a, the insertion hole 48 is formed in the capillary 3.
Since 5 having a small diameter that can be inserted is sufficient, there is almost no influence on the ball shape.

Further, since the torch electrode 36a is a fixed torch electrode supported by the torch rod 36 fixed to the bonding head 34, the wire bonding processing time can be shortened as compared with the movable torch electrode 20a shown in FIG. . That is, in the case of the movable torch electrode 20a, the torch electrode 20 is formed in order to form the molten ball 4 on the tip of the wire 3.
a moves to the vicinity of the capillary 12 and stops, but at this time, the torch electrode 20a vibrates due to inertia, and it is necessary to wait for the operation of forming the molten ball 4 by electric discharge until the vibration stops. On the other hand, the fixed torch electrode 36a of the present embodiment shown in FIG. 1 does not have the above-mentioned movement and stop itself, and hence vibrations associated therewith do not occur. Therefore, immediately after the completion of the wire bonding operation in the previous step, the molten ball 4 is The forming operation can be performed, and thus the wire bonding apparatus 30 does not impair the wire bonding processing time. For example, in the fixed torch electrode 36a, the forming operation of the molten ball 4 can be shortened by about 15 ms per operation as compared with the movable torch electrode 20a, so that the wire bonding apparatus 30 can shorten the wire bonding processing time accordingly.

Further, since the insertion hole 48 for inserting the capillary formed in the torch electrode 36a has a tapered shape whose diameter becomes smaller toward the capillary 35 side, the peripheral edge portion 49 of the insertion hole of the torch electrode 36a on the capillary 35 side is formed. Since the edge shape is sharpened toward the capillary 35 side, the discharge 50 can be easily generated between the sharp edge portion 49 and the tip of the wire 3.

The movable torch electrode 20 shown in FIG.
a requires a moving mechanism such as an arm 21, an electromagnet 23, and a coil spring 25, but the fixed torch electrode 3 shown in FIG.
6a is integrally supported by a torch rod 36 fixed to the bonding head 34. Therefore, the wire bonding apparatus 3 including the fixed torch electrode 36a
The structure of 0 can be simplified.

[0027]

As described above, according to the wire bonding apparatus of the present invention, the molten balls can be stably formed without impairing the wire bonding processing time.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a wire bonding apparatus according to the present invention with a part thereof broken away.

FIG. 2 is a perspective view showing a tip portion of the torch rod in FIG.

FIG. 3 is a cross-sectional view showing a discharge state between a torch electrode and a wire.

FIG. 4 is a side view showing a wire bonding apparatus including a conventional fixed torch electrode with a part broken away.

FIG. 5 is a perspective view showing a conventional movable torch electrode.

[Explanation of symbols]

 1 Semiconductor Pellet 2 Lead Frame 3 Wire 4 Molten Ball 30 Wire Bonding Device 31 Lead Frame Transfer Device 32 XY Table 33 Bonding Arm 34 Bonding Head 35 Capillary 36 Torch Rod 36a Torch Electrode 39 Cover 40 Gas Supply Piping 41 Forming Gas 44 Opening 45 Gas Flow path 47 Forming gas 48 Capillary insertion hole 49 Capillary insertion hole peripheral portion 50 Discharge

Claims (2)

[Claims] 1. A bonding head which is movable in a horizontal direction, a capillary which is provided in the bonding head so as to be able to move up and down through a bonding arm, and through which a wire is inserted, and a capillary which is fixed to the bonding head and inserted into the capillary. A torch rod that causes a forming gas to flow toward the tip of the wire, and a discharge is generated between the tip of the wire and the tip of the wire to form a molten ball at the tip of the wire in the atmosphere of the forming gas. A torch rod having a torch electrode, and a lead frame transfer device, which is disposed below the capillary and transfers and guides a lead frame on which semiconductor pellets are mounted in an atmosphere of forming gas, the bonding head and the capillary. By the operation of
In a wire bonding apparatus for bonding the electrode of the semiconductor pellet and the lead of the lead frame with the wire in an atmosphere of a forming gas of the lead frame carrier, the torch rod is formed in a tubular shape and is internally formed. A flow path for flowing the forming gas is formed, and the torch electrode at the tip of the flow path extends beyond just below the capillary. Furthermore, the torch electrode can be inserted into the capillary just below the capillary. A wire bonding apparatus having a through hole formed therein. 2. The insertion hole formed in the torch electrode,
The wire bonding apparatus according to claim 1, wherein the wire bonding apparatus has a taper shape whose diameter decreases toward the capillary side.