JPH08340026A - Wire bonding equipment - Google Patents

Abstract

PURPOSE: To prevent deformation strain left in a wire by a clamper from traveling a wedge by blowing air against the wire stretching to the lower end of the wedge to give tension to the wire, and arranging a wire clamper beteen an ultrasonic horn and the wedge. CONSTITUTION: An air tensioner 12 which blows air against a wire 9 and give tension to the wire 9 is arranged between a wire supplying source and an ultrasonic horn 6. A wire clamper 13 pinching a wire is arranged between the ultrasonic horn 6 and a wedge 7. The air tensioner 12 and the wire clamper 13 are fixed to an arm 14 extending from swinging mechanism which retains the ultrasonic horn 6 rockably movably, and maintains a constant positional relation to the ultrasonic horn 6 which moves horizontally and vertically. The air tensioner 12 has an air nozzle 12d facing the ultrasonic horn 6 between loops 12b and 12c which guide the wire 9 to a base 12a, in the routing direction of the wire 9.

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 bonding apparatus using a wedge as a bonding tool.

[0002]

2. Description of the Related Art Electronic components such as semiconductor devices are manufactured by electrically connecting electrodes of an electronic component body and external leads, and by covering a main portion including the electronic component body with an exterior. A metal thin wire is generally used for electrical connection between the electrodes of the electronic component body and the external leads. Gold, copper, and aluminum are used for this wire, but in the case of a power semiconductor device that controls a large current, a wire with a large wire diameter is required, but on the other hand, if the wire diameter becomes large, the cost increases, so it is relatively inexpensive. Aluminum is used. FIG. 4 shows an example of a bonding device used for connecting wires such as a power semiconductor device. In the figure, reference numeral 1 is a lead frame, which is composed of a heat dissipation plate 3 for fixing an electronic component body, for example, a semiconductor pellet 2, and a set of leads 4, and one lead 4a is connected to the heat dissipation plate 3, In the illustrated example, the other lead 4b, which is shown as one, has one end arranged near the heat dissipation plate 3.

Reference numeral 5 is a guide rail provided with a moving mechanism (not shown) for guiding the lead frame 1 and moving the lead frame 1 at a predetermined pitch. Reference numeral 6 extends from the side of the guide rail 5 onto the guide rail 5 and is bonded to one end thereof. An ultrasonic horn to which the tool 7 is fixed is supported by a swing mechanism (not shown) equipped with an ultrasonic vibrator at the other end and moved by an XY table.
Bonding tool 7 with ultrasonic vibration applied appropriately
Move horizontally and vertically. The bonding tool 7 is of a wedge type as shown in FIG. 5, and has leg pieces 7a and 7b having different projecting lengths, and the leg piece 7a having a long projecting length is set to the outer end side of the ultrasonic horn 6 and its lower end. A groove 7c is formed parallel to the axis of the horn 6, and the groove 7c is formed on the other leg piece 7b.
A guide hole 7d is formed to face c and open. 8
Is a wire supply source including a spool 10 for feeding and supplying the wire 9, and the wire 9 fed from the wire supply source 8
Is a through hole 6 formed through the middle portion of the ultrasonic horn 6.
a and the tip portion is housed in the groove 7c through the guide hole 7d of the wedge 7 sequentially. This device has a lead frame 1
A mechanism for positioning and fixing the guide rail to the guide rail 5 is attached, but is not shown.

The operation of this device will be described below. First,
In the previous step, the semiconductor pellets 2 are fixed on the heat dissipation plate 3, the lead frame 1 supplied on the guide rails 5 is positioned at a predetermined position, and the wedges 7 are electrodes on the semiconductor pellets 2 which are the first bonding positions (see FIG. (Not shown)
When the ultrasonic horn 6 is positioned above, the tip of the wire 9 is brought into contact with the electrodes by polymerization, and ultrasonic vibration is applied to the polymerization portion while the wedge 7 is being pressed to weld the polymerization interface. When the first bonding is completed in this way,
The lead 4 which is the second bonding position while raising the wedge 7 and feeding out the wire 9 from the wire supply source 8
b Move up. Then, the middle portion of the wire 9 is pressed against the free end portion of the lead 4 by the lower end of the wedge 7 to apply ultrasonic vibration to weld the polymerization interface. After that, the wedge 7 is slightly raised to move the wire 9 while feeding it out, and the wire 9 is cut to complete one bonding operation. The cutting of the wire 9 is performed by moving the front end of the wedge 7 to the edge of the lead 4 and shearing with this edge, a method of cutting with a knife edge (not shown), and cutting and forming a cut in the wire with the knife edge. There are ways.

In this way, when the connection between the first and second bonding positions is completed, the wedge 7 is moved to the next electrode and the bonding work is sequentially performed, and the above operation is performed on one semiconductor pellet 2. repeat. This wire bonding apparatus is applied to a transistor or a thyristor having a small number of electrodes, that is, leads, and having the wires extending in substantially the same direction and having a wire diameter of 100 to 500 μm when the wire is aluminum. . By the way, since the wire 9 is wound around the spool 10, the curled deformation remains in the unwound wire, and the wire supply source 8 causes the spool 1 to rotate as in the illustrated example.
In the structure in which the wire is fed from 0 through its winding core, twisting deformation is added to the wire 9, and if these deformations are eliminated by the time of reaching the wedge 7, normal bonding can be performed, but this deformation at the bonding position. Remains, when the first bonding is completed and the deformation of the wire is released with the tip of the wire 9 fixed, the wire becomes spiral between the first and second bonding positions. There is a problem that the wire is deformed and a part of the wire comes close to or comes into contact with the semiconductor pellet 2 or the heat dissipation plate 3 to cause a decrease in withstand voltage or a short circuit.

Therefore, the wire 9 is braked by covering the through hole 6a of the ultrasonic horn 6 with a rubber cylinder 11 having a shape shown in FIG. This cylindrical body 11 is formed with a cut 11a extending from one end in the axial direction on its peripheral surface. The cut 11a is located in the through hole 6a of the ultrasonic horn 6, and the wire 9 is elastically cut by the cut 11a. Braking force is applied to the sandwiching wire 9. Thus, when the wire 9 is braked between the wire source 8 and the wedge 7, the wire 9
Deformation concentrates on the notch 11a, the deformation strain of the wire passing through the through hole 6a is relaxed, and the bonded wire can be prevented from being deformed in a spiral shape.

[0007]

However, since the rubber tubular body 11 is worn out due to friction with the wire when it is used for a long time, it is necessary to periodically shift the position of the notch 11a and the through hole 6a. Since the braking state is slightly different depending on the position of the cut 11a, it is necessary to determine the best attachment position by observing the bonding state, and there is a problem that the position adjustment is complicated. Further, although the cylindrical body 11 is lightweight, there is a problem that it interferes with the ultrasonic waves propagating in the ultrasonic horn 6 and affects the bonding quality. As another method of braking the wire 9, there is a method of applying air to the wire to give tension, but the front of the through hole 6a is less likely to be affected,
It was not possible to prevent the deformation of the wire from completely reaching the wedge 7 portion. In JP-A-55-123137, a means for mechanically and elastically pulling the wire from the ultrasonic horn side and a means for appropriately sandwiching the wire are sequentially arranged between the ultrasonic horn and the wedge. Although a wire bonding device is disclosed, this is a device that detects the end position of an aluminum wire having a wire diameter of about 30 μm, which has good flexibility, and enables the final bonding without disconnection. We could not solve the problem caused by residual deformation strain.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been proposed for the purpose of solving the above problems, in which a wedge is fixed at one end and a wire insertion hole is formed in the middle, and the ultrasonic vibration extends substantially horizontally. An ultrasonic horn that is applied and moves horizontally and vertically, and an air that is placed between the wire and the supply source and the ultrasonic horn and that blows air from the wire supply source and extends to the lower end of the wedge to give tension to the wire. There is provided a wire bonding apparatus including a tensioner and a wire clamper which is arranged between an ultrasonic horn and a wedge and which appropriately clamps a wire. By fixing the air tensioner and the wire clamper to the arm extending substantially parallel to the ultrasonic horn, the mutual positional relationship can be fixed and stable operation can be performed. Further, by setting the air blowing direction of the air tensioner to the ultrasonic horn side, undesired vibration of the wire can be reduced.
Further, the wire clamper can prevent the wire from being separated from the wedge by providing a means for guiding the wire in a portion that holds the wire.

[0009]

According to the above means for solving the problem, the wire is tensioned and braked so that the deformation strain remaining in the wire is prevented from propagating to the wedge by the clamper, and good wire bonding can be performed.

[0010]

EXAMPLE An example of the present invention will be described below with reference to FIG. 1 by applying it to the wire bonding apparatus shown in FIG. In the figure, the same parts as those in FIG. 4 are designated by the same reference numerals, and overlapping description will be omitted. The difference in the figure is that the wire 9 is blown with air between the wire supply source 8 and the ultrasonic horn 6.
The air tensioner 12 that gives tension to the wire is arranged, and the wire clamper 13 that appropriately clamps the wire is arranged between the ultrasonic horn 6 and the wedge 7. The air tensioner 12 and the wire clamper 13 are swinging mechanisms (vertical moving mechanisms) that swingably support the ultrasonic horn 6.
The ultrasonic horn 6 is fixed to an arm 14 extending from the horizontal direction and vertically moves, and maintains a fixed positional relationship with the ultrasonic horn 6. As shown in FIG. 2, the air tensioner 12 has a pair of loops 12b and 12c for guiding the wire 9 in the drawing direction of the wire 9 which is implanted in the base 12a.
The air discharge port 12d is opened between c and the air discharge port 12d
d is opposed to the ultrasonic horn 6.

Further, as shown in FIG. 3, the wire clamper 13 has a pair of clamper pieces 13a, 1a whose outer shape is substantially Y-shaped.
It consists of 3b. The clamper pieces 13a, 13b have nipping portions 13c, 13d at their lower ends, shaft supporting portions 13f, 13g coaxially supported by a common shaft 13e at their lower ends, and adsorption portions 13h, 13i made of a magnetic member at their upper ends, respectively. An exciting coil 13j is attached to one of the attracting portions 13h, and a coil spring 13k is connected between opposing surfaces of the shaft supporting portions 13f and 13g. Also, the holding portion 13c,
Pins 13m and 13n, of which the tips are inserted in the facing surface with their positions vertically displaced, project from the facing surface of 13d.
The rotating shaft 13e of the wire clamper 13 and the exciting coil 1
3j is fixed to a support member (not shown) extending from the arm 14.

The operation of this device will be described below. First,
The lead frame 1 having the semiconductor pellets 2 fixed on the heat sink 3 in the previous step is supplied onto the guide rails 5, and the lead frame 1 is positioned at a predetermined position. This time,
The wire clamper 13 does not energize the exciting coil 13j and holds the wire 9 with the coil springs 13k closing the holding portions 13c and 13d.
The air tensioner 12 applies air to the wire 9 to give tension. Since air is blown onto the wire 9 from above, the wire 9 is plastically deformed by its own weight and blowing pressure, and the curl deformation and the twisting deformation of the wire passing through the air tensioner 12 are eliminated or alleviated. Further, since the weight of the wire 9 and the blowing pressure are applied in the same direction, there is no unwanted vibration of the wire and the wire 9 is smoothly introduced into the through hole 6a, so that the wire can be stably supplied. Next, the wedge 7 is positioned on the first bonding position, the ultrasonic horn 6 is lowered to bring the tip of the wire 9 into overlapping contact with the electrode, and the wire clamper 13 is energized and opened to its exciting coil 13j to open the wedge. In step 7, ultrasonic vibration is applied while the polymerized portion is pressurized to weld the polymerized interface.

When the first bonding is completed in this way, the wedge 7 is raised and the wire 9 is paid out from the wire supply source 8 and moved onto the lead 4b which is the second bonding position. At this time, even if the twisting deformation that causes the spiral deformation of the wire 9 remains,
Since the wire 9 is guided and fed between the pins 13m and 13n of the wire clamper 13, the wire is plastically deformed even in this portion, the above deformation is eliminated, and the deformation strain of the wire led out from the wedge 7 is reduced. Then, the middle portion of the wire 9 is pressed against the free end portion of the lead 4 by the lower end of the wedge 7 to apply ultrasonic vibration to weld the polymerization interface.

After that, the wedge 7 is slightly raised and the wire 9 is moved so as to be paid out, and the wire clamper 1 is moved.
The exciting coil 13j of No. 3 is not energized, the clamping portions 13c and 13d are closed by the spring 13k to clamp the wire 9, and the wire 9 protruding from the wedge 7 is cut to complete one bonding operation. In this way,
When the connection between the first and second bonding positions is completed, the wedge 7 is moved to the next electrode and the bonding work is sequentially performed, and the above operation is repeated for one semiconductor pellet 2. The present invention is not limited to the above-described embodiments, but can be applied to general electronic devices such as semiconductor devices as well as hybrid integrated circuit devices that are electrically connected by wires. Further, the air tensioner 12 can efficiently apply tension even to a thick and inferior wire by discharging the air between the wall surfaces facing the air outlet 12d. Also one air outlet 12
A pair of loops 12b and 12c are arranged close to each other on both sides of the air flow path of d, or a pair of air discharge ports are opened on both sides of one loop to press the wire against the loop and efficiently deform the strain remaining on the wire. It can also be removed.

[0015]

As described above, according to the present invention, it is possible to prevent the defective bonding due to the curl deformation and the twist deformation of the wire, the time change of the air tensioner and the wire clamper does not change, and the stable operation is performed well. You can

[Brief description of drawings]

FIG. 1 is a side view of a wire bonding apparatus showing an embodiment of the present invention.

FIG. 2 is a side view showing an example of an air tensioner used in the apparatus shown in FIG.

FIG. 3 is a front view showing an example of a wire clamper used in the apparatus shown in FIG.

FIG. 4 is a side view of a wire bonding apparatus which is a premise of the present invention.

[Fig. 5] Side sectional view of the wedge

FIG. 6 is a perspective view of a tubular body that brakes a wire.

[Explanation of symbols]

 6 Ultrasonic horn 6a Wire insertion hole 7 Wedge 8 Wire supply source 12 Air tensioner 13 Wire clamper

Claims (4)

[Claims] 1. An ultrasonic horn that has a wedge fixed to one end and a wire insertion hole formed in the middle, extends substantially horizontally, and receives ultrasonic vibration to move horizontally and vertically, a wire supply source and an ultrasonic wave. An air tensioner that is arranged between the ultrasonic horn and the wedge, and that is provided between the ultrasonic horn and the wedge and that blows air to the wire that is extended from the wire supply source and that extends to the lower end of the wedge to apply tension to the wire. And a wire bonding device. 2. The wire bonding apparatus according to claim 1, wherein the air tensioner and the wire clamper are fixed to an arm extending substantially parallel to the ultrasonic horn and interlocking with the ultrasonic horn. 3. The wire bonding apparatus according to claim 1, wherein the air blowing direction of the air tensioner is set to the ultrasonic horn side. 4. The wire bonding apparatus according to claim 1, wherein the wire clamper is provided with a means for guiding the wire at a portion for holding the wire.