JPH0521501A - Device and method for detecting high frequency in wire bonding device - Google Patents

Abstract

PURPOSE:To improve the reliability of a wire bonding device so as to form an optimum ball diameter by detecting the occurrence of a high frequency at the time of abnormal discharge and notifying the abnormal discharge based on the occurrence of the high frequency. CONSTITUTION:A high-frequency detection circuit 13 is constituted so that the circuit 13 can detect the occurrence of abnormal discharge by detecting a high frequency generated from a discharge electrode 10. Therefore, the occurrence of such an accident that a ball is buried in a capillary 9, and so on, can be prevented and, at the same time, a ball having a suitable ball diameter can be formed. In addition, since the occurrence of abnormal discharge can be notified quickly, the reliability of a wire bonding device can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses 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 arranged on a lead frame, in a process of assembling a semiconductor device. The present invention relates to a wire bonding device for connecting with each other.

[0002]

2. Description of the Related Art Conventionally, as a device for connecting an electrode on a semiconductor chip, which is a first bonding point, and a lead, which is a second bonding point, using a gold wire or a wire such as copper or aluminum, the circuit shown in FIG. There is known a wire bonding apparatus for forming a ball by using.

As shown in FIG. 2, a power supply circuit 1 for generating a high voltage is connected to an E ₁ terminal of a high voltage constant current element 2 via a resistor R. This high voltage constant current element 2 is composed of a transistor (or FET), an E ₁ terminal is an emitter (or source), a B ₁ terminal is a base (or gate), and a C ₁ terminal is a collector (or drain). is there.

The B ₁ terminal is connected to the output side of the differential amplifier 3. One end of the amplifier 3 on the input side is connected to the power supply circuit 1, and the other end is connected to the resistor R via the reference voltage generation circuit 4. Further, the C ₁ terminal is connected to the discharge electrode 10 via the switch circuit 5. The switch circuit 5 is connected to a timer 6 that turns on / off the switch circuit 5 for a certain period of time, and the timer 6 is driven by a trigger signal Tr. The wire 8 is inserted through the capillary 9, and the clamper 7 is connected to the power supply circuit 1.

In order to form a ball using the apparatus having the above structure, the switch circuit 5 is driven by the timer 6 driven by the timer 6 in response to an external trigger signal Tr. A maximum voltage of about 1200 V is applied to the terminal on the 5a side of the switch circuit 5. Therefore,
When this switch is turned on, a high voltage is applied to the discharge electrode 10 to start discharge with the tip of the wire 8. Then, the voltage induced across the resistor R by the high-voltage power supply from the power supply circuit 1 is input to the reference voltage generation circuit 4 and the differential amplifier 3. The differential voltage from the reference voltage generated by the reference voltage generating circuit 4 is output from the differential amplifier 3 and the B ₁ terminal is biased, and the high voltage constant current element 2 performs constant current control. Then, the tip of the wire is melted by the discharge energy E between the discharge electrode 10 and the wire 8 to form a ball shape.

[0006]

However, the conventional device has the following drawbacks. That is,

In the conventional device, voltage control is performed by the differential amplifier 3 and constant current control is performed by the high-voltage constant current element 2, but an amplifier having a relatively high gain is used for this differential amplifier 3. Therefore, there is a drawback in that a constant current cannot be stably maintained because a phase delay occurs and quick control is not performed. As a result, a phase delay occurs, the constant current control is not stable, and an appropriate current cannot be obtained due to a decrease in the spark discharge current for sustaining the discharge.

Further, in the conventional device, when the discharge electrode 10 is in an oxidized state or in an eroded state, an abnormal discharge occurs and a high frequency of several hundred KHz to several MHz is generated during the discharge. A normal voltage waveform as shown in FIG. 3 is obtained when a normal discharge is generated without generating such a high frequency, but when a high frequency is generated and an abnormal discharge is generated, the waveform is disturbed. Normal voltage waveform cannot be obtained. During this abnormal discharge, the ball diameter may be reduced or deformed due to the influence of high frequency. Therefore, there is a drawback that a ball having an optimum ball diameter cannot be obtained. Moreover, if the device is continuously operated in this state, the balls will be buried in the capillaries, and the device operation must be stopped in order to replace the capillaries, resulting in poor workability and impaired device reliability. There are also drawbacks.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the prior art. It is detected that a high frequency is generated at the time of abnormal discharge, and a high frequency is generated by the detection output to perform the abnormal discharge. It is an object of the present invention to provide a high-frequency detection device in a wire bonding device and a method therefor capable of improving the reliability of the device and forming an optimum ball diameter as described above.

[0010]

According to the present invention, a high voltage is applied between the tip of a wire protruding from the tip of a capillary and a discharge electrode to cause discharge, and the discharge energy melts the tip of the wire. In a wire bonding device for forming balls, a power supply circuit, a current control circuit connected to the power supply circuit, a discharge electrode connected via the current control circuit, and a clamper connected to the power supply circuit. A current control circuit and a high frequency detection circuit connected between the discharge electrodes and between the clamper, the high frequency detection circuit being configured to detect a high frequency generated from the discharge electrode during abnormal discharge. is there. The present invention also provides a power supply circuit, a current control circuit connected to the power supply circuit, discharge electrodes connected via the current control circuit, a clamper connected to the power supply circuit, and the current control circuit. And a high-frequency detection circuit connected between the discharge electrodes and between the clamper, and when the high-frequency detection circuit detects a high-frequency generated from the discharge electrodes during abnormal discharge, the notification means is used for notification. It is a thing. Furthermore, the high-frequency detection method according to the present invention causes a discharge by applying a high voltage between the tip of the wire protruding from the tip of the capillary and the discharge electrode, and the discharge energy melts the tip of the wire. A wire bonding device for forming a ball, which can detect a high frequency generated from a discharge electrode during abnormal discharge.

[0011]

EXAMPLE An example of the high frequency detecting device in the wire bonding apparatus according to the present invention will be described below.

FIG. 1 is a diagram showing a circuit configuration of a wire bonding apparatus according to the present invention. It should be noted that components having the same functions and configurations as those of the configuration of the conventional apparatus shown in FIG.

In FIG. 1, a power supply circuit 1 that generates a high voltage is connected to a current control circuit 12. The current control circuit 12 is composed of a constant current circuit 12a and a high voltage constant current switching element 12b. The constant current circuit 12a generates a constant current and supplies it to the high voltage constant current switching element 12b in the subsequent stage. Also, the high voltage constant current switching element 12b
A device similar to the conventional high-voltage constant current device 2 is used, but the conventional high-voltage constant current device 2 performs constant current control, and a maximum voltage of about 1200 V is applied to the switch circuit 5 in the subsequent stage. In contrast to this, in the present embodiment, the voltage is applied to the high voltage constant current switching element 12b.
The high voltage constant current switching element 12b is composed of a transistor (or FET), an E ₂ terminal is an emitter (or source), a B ₂ terminal is a base (or gate), and a C ₂ terminal is a collector (or drain). Is. The B ₂ terminal is connected to the switch circuit 5 via the drive power supply circuit 11 connected between the power supply circuit 1 and the current control circuit 12, and a loop is formed by these. The switch circuit 5 is connected to a timer 6 that turns on / off the switch circuit 5 for a certain period of time, and the timer 6 is driven by a trigger signal Tr.

Further, C _{2 of} the high voltage constant current switching element 12b is
The terminal is connected to the discharge electrode 10, and this C ₂
A high frequency detection circuit 13 is connected between the terminals and the discharge electrode 10 and between the clamper 7. The high frequency detection circuit 13 is composed of a detection circuit including a diode and the like. This high frequency detection circuit 13 has a frequency of several hundred KHz to several MHz.
It is possible to detect a wide range of frequencies. At the time of discharging from the discharge electrode 10 by this high frequency detection circuit 13 (when discharging,
It also includes the time when the discharge is started and the time when the discharge is being performed. ) Is detected, it is determined that abnormal discharge has occurred in the control circuit (not shown) based on the detection signal, and a notification is given by a display or alarm device. It can be announced by means (not shown). Based on this notification, the operation of the apparatus is stopped by operating the automatic or external operation means. A wire 8 is inserted through the capillary 9.

In order to form a ball using the apparatus having the above structure, the timer 6 is driven by the external trigger signal Tr and the switch circuit 5 is driven. on the other hand,
In the high voltage constant current switching element 12b in the subsequent stage of the constant current circuit 12a of the current control circuit 12, the switch of the switch circuit 5 is closed and turned on, and the B of the high voltage constant current switching element 12b is turned on.
_{The two} terminals are biased and the element 12b is driven to generate E ₂
A maximum voltage of about 1200 V is applied between the C ₂ and C ₂ terminals. Then, a discharge is caused between the discharge electrode 10 and the tip of the wire 8, and the discharge energy E causes the wire 8 to move.
The tip of is melted to form a ball. The current flowing between E ₂ and C ₂ at this time is a substantially constant current. Further, according to the present embodiment, even when the spark discharge becomes unstable due to a change in the electrode distance between the discharge electrode 10 and the wire 8 or oxidation of the spark discharge electrode, high voltage constant current switching is performed. Since the element 12b is switched quickly, the response speed is fast and high-speed switching without phase delay is possible and the device is simple.

On the other hand, in this embodiment, since the high frequency detecting circuit 13 is provided between the C ₂ terminal and the discharge electrode 10 and between the clamper 7, the discharge is caused by the oxidation state or the erosion state of the discharge electrode 10. At times, when a high frequency as shown in FIG. 3 is generated and abnormal discharge is generated, this high frequency is detected and a notification means such as a display or an alarm (not shown) notifies that the high frequency is generated. Based on the information from the notification means, the operation of the device is stopped automatically or by operating the operation means (not shown) to form a ball having a reduced ball diameter or a deformed ball due to the generation of a high frequency, and the inside of the capillary 9 is formed. It is possible to prevent accidents such as the ball being buried in the ground. Then, the discharge electrode 10 is inspected and cleaned,
By replacing the battery, stable spark discharge can be performed and continuous operation of the device becomes possible.

In the present embodiment, the notification by the notification means is made only when the frequency detected by the high frequency detection circuit 13 is equal to or higher than the value preset in the control circuit (not shown) at the time of self-teaching or the like. You may do it. In addition, the timing and conditions for this notification can be appropriately set depending on the state of the device.

[0018]

As described above, according to the present invention, when an abnormal discharge occurs due to the generation of a high frequency, it is possible to detect this high frequency and confirm that the discharge is abnormal. Therefore, it is possible to prevent the ball from being buried in the capillary. Accidents can be prevented and a ball having a good ball diameter can be formed. Further, according to the present invention, it is possible to promptly notify that there is a risk of high frequency generation and abnormal discharge, and to stop the operation of the device based on the notification information. There is an effect that the property is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of a ball bonder forming apparatus for a wire bonder according to the present invention.

FIG. 2 is a diagram showing a circuit configuration of a conventional wire bonder ball forming apparatus.

FIG. 3 is a voltage waveform diagram showing that a normal waveform and a high frequency are generated to cause an abnormal discharge.

[Explanation of sign]

1 power supply circuit 5 switch circuits 12 Current control circuit 12a constant current circuit 12b High voltage constant current switching element 13 High frequency detection circuit

Claims (3)

[Claims] 1. A wire bonding for forming a ball by applying a high voltage between a tip of a wire protruding from a tip of a capillary and a discharge electrode to cause a discharge, and the discharge energy melts the tip of the wire to form a ball. In the device, a power supply circuit, a current control circuit connected to the power supply circuit,
A discharge electrode connected via the current control circuit, a clamper connected to the power supply circuit, and a high frequency detection circuit connected between the current control circuit and the discharge electrode and the clamper, A high-frequency detection device in a wire bonding device, wherein the high-frequency detection circuit is capable of detecting a high frequency generated from a discharge electrode during abnormal discharge. 2. A wire bonding for forming a ball by applying a high voltage between a tip of a wire protruding from a tip of a capillary and a discharge electrode to cause a discharge and melting the tip of the wire by the discharge energy. In the device, a power supply circuit, a current control circuit connected to the power supply circuit,
A discharge electrode connected via the current control circuit, a clamper connected to the power supply circuit, and a high frequency detection circuit connected between the current control circuit and the discharge electrode and the clamper, A high-frequency detection device in a wire bonding device, wherein when a high-frequency generated from the discharge electrode is detected by the high-frequency detection circuit during abnormal discharge, the notification means notifies the high-frequency detection device. 3. A wire bonding for forming a ball by applying a high voltage between a tip of a wire protruding from a tip of a capillary and a discharge electrode to cause a discharge and melting the tip of the wire by the discharge energy. A high frequency detecting method in a wire bonding apparatus, which is capable of detecting a high frequency generated from a discharge electrode during abnormal discharge.