JP2757237B2 - Ball forming device for wire bonder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for assembling a semiconductor device by using a wire at a first bonding point, for example, an electrode on a semiconductor chip, and a second bonding point, for example, an external lead provided on a lead frame. TECHNICAL FIELD The present invention relates to an apparatus and a method for forming a wire for a wire bonder in a wire bonder to be connected by a wire.

[0002]

2. Description of the Related Art A conventional apparatus for connecting an electrode on a semiconductor chip serving as a first bonding point and a lead serving as a second bonding point using a wire such as a gold wire or aluminum is shown in FIG. BACKGROUND ART A ball forming apparatus for a wire bonder having a circuit configuration is known.

The device shown in FIG. 3 includes a power supply circuit 11 for generating a high voltage, a constant current circuit 12 connected to the power supply circuit 11 for generating a constant current, a switching circuit 13, and a switching circuit 13 for a predetermined time. It comprises a timer 14 for turning on / off, a ballast 15 connected to the switching circuit 13, a discharge electrode 19, a clamper 16, a capillary 18, and a wire 17 inserted through the capillary 18. The ballast 14 uses a large value resistor R for stabilizing spark discharge.

In order to form a ball using the apparatus having the above-described configuration, a timer 14 is triggered by an external trigger signal Tr to drive a switching circuit 13 to turn on a switch. When this switch is turned on, a constant current is supplied from the constant current circuit 12 and a high voltage, for example, a voltage from about 1500 V to about 3000 V is applied to the discharge electrode 19 via the ballast 15. A discharge is generated between the discharge electrode 19 and the tip of the wire 17, and the tip of the wire is melted by the discharge energy to form a ball.

[0005]

However, in the conventional apparatus, the voltage between the electrodes required to start the discharge is directly proportional to the distance S between the electrodes, that is, the distance between the discharge electrode 19 and the tip of the wire 17. Therefore, if the distance S between the electrodes is slightly larger than a predetermined value, the discharge is not performed, or the discharge is interrupted.

Accordingly, the present invention has been made in view of the above-mentioned drawbacks of the prior art, and a ball formation for a wire bonder capable of forming a ball having an optimum ball diameter by stabilizing and maintaining discharge. It is intended to provide a device.

[0007]

According to the present invention, a discharge is caused by applying a high voltage between a tip of a wire protruding from the tip of a capillary and a discharge electrode, and the tip of the wire is melted by the discharge energy. A ball forming apparatus for a wire bonder for forming a ball by using a laser beam irradiator that emits a laser beam having an irradiation range extending from at least the distal end of the wire to the discharge electrode.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a ball forming apparatus for a wire bonder according to the present invention will be described with reference to the accompanying drawings. The apparatus for forming a ball for a wire bonder according to the present invention is configured in the same manner as the conventional apparatus shown in FIG. 3 except for the parts described below. In the following description, portions that are the same as or correspond to those of the conventional device shown in FIG. 3 will be described using the same reference numerals.

FIG. 1 shows a main part of a ball forming apparatus for a wire bonder according to a first embodiment of the present invention.
As shown in the drawing, this apparatus has a laser beam irradiator 1 disposed on the side of a capillary 18 and a discharge electrode 19. The laser beam irradiator 1 emits a laser beam 2 in a direction substantially perpendicular to the axial direction of the wire 17, in this case, in a horizontal direction.
Has an irradiation range extending from the distal end portion to the discharge electrode 19. In this way, by irradiating the laser beam so as to capture both the tip of the wire to be mutually discharged and the discharge electrode 19 within the irradiation range, the gas between and near the two is excited to insulate the gas. Destroyed, spark discharge 3
Is performed as if induced, and the spark discharge starting voltage decreases. Therefore, as shown by a two-dot chain line in the figure, the distal end of the wire 17 is melted by the discharge energy to form a ball 17a having an optimum ball diameter.

FIG. 2 shows a main part of a ball forming apparatus for a wire bonder according to a second embodiment of the present invention.
As shown, in this apparatus, the laser beam irradiator 5 is disposed above the capillary 18 so that the laser beam 2 forms an acute angle with respect to the axis of the wire 17, that is, the wire Tip and discharge electrode 19
Irradiation towards. As the laser beam 2 emitted from the laser beam irradiator 5 in this apparatus, a laser beam 2 that is more focused than that shown in FIG. 1 is used.

According to the above construction, the laser beam 2 captures both the tip of the wire and the discharge electrode 19 within the irradiation range, so that the gas between them is excited and the apparatus shown in the first embodiment shown in FIG. Similarly, spark discharge 3 easily occurs.

If the laser beam 2 is irradiated at an acute angle to the axis of the wire 17 as described above, the tip of the wire and the discharge electrode 19 can be captured even if the irradiation range of the laser beam 2 is small. And the output of the laser can be suppressed to be small. In addition, with such a configuration, the laser beam irradiator 5 can be arranged close to the capillary 18, so that the size of the apparatus can be easily reduced.

[0013]

As described above, according to the present invention, the gas between both the tip of the wire and the discharge electrode is excited by laser beam irradiation to cause dielectric breakdown, so that the discharge is reliably performed. In addition, there is an effect of being stabilized without interruption. In addition, there is an effect that the voltage between electrodes required for discharging can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view including a main part and a partial cross section of a ball forming apparatus for a wire bonder according to a first embodiment of the present invention.

FIG. 2 is a side view including a main part and a partial cross section of a ball forming apparatus for a wire bonder as a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional ball forming apparatus for a wire bonder.

[Explanation of symbols]

 1, 5 laser beam irradiator 2 laser beam 17 wire 18 capillary 19 discharge electrode

Claims (1)

(57) [Claims] 1. A wire bonder for generating a discharge by applying a high voltage between a tip of a wire protruding from the tip of a capillary and a discharge electrode, and melting the tip of the wire by the discharge energy to form a ball. A ball forming apparatus for a wire bonder, comprising: a laser beam irradiator that emits a laser beam having an irradiation range extending from at least a tip end of the wire to the discharge electrode.