Wire bonding apparatus, circuit for wire bonding apparatus, and method for manufacturing semiconductor device

The present invention comprises: a spool (10); a clamper (22); a torch electrode (31); a high-voltage power source circuit (30); a non-bonding detection circuit (40); a first changeover switch (50) switching a connection between the spool (10) and the high-voltage power source circuit (30) or the non-bonding detection circuit (40); and a relay (53) turning on/off a connection between the clamper (22) and a spool side of the first changeover switch (50), and comprises a control part (60) that sets the first changeover switch (50) to the high-voltage power source circuit side and turns off the relay (53) to generate electric discharge, and that sets the first changeover switch (50) to the non-bonding detection circuit side and turns on the relay (53) to perform non-bonding detection. Due to this configuration, electric corrosion of a wire clamper can be suppressed and non-bonding detection can be carried out with a simple configuration.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 application of the international PCT application serial no. PCT/JP2017/012080, filed on Mar. 24, 2017, which claims the priority benefit of Japan application no. 2016-061147, filed on Mar. 25, 2016. The entirety of each of the abovementioned patent applications is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The present invention relates to a wire bonding apparatus, a structure of a circuit for the wire bonding apparatus, and a method of manufacturing a semiconductor device.

BACKGROUND ART

A wire bonding apparatus that connects between electrodes of devices such as semiconductor chips disposed on a circuit board and leads of a circuit board with a metal wire is frequently used. Wire bonding is a method in which a free air ball is formed at a front end of a wire by an electric torch, the free air ball is bonded to an electrode of a device by a capillary, then the capillary is looped, the wire is pressed against a lead of the circuit board by the capillary, and thereafter the wire is pulled up in a state of being gripped by a clamper to cut the wire. The free air ball is formed by clamping the wire with the clamper, applying a high voltage for forming a free air ball to the wire, and generating electrical discharges between the wire and the electric torch to melt the wire. At this time, there are cases in which secondary electrical discharges are generated between the clamper clamping the wire and the wire and this causes electrolytic corrosion on a surface of the clamper. When scratches are made on the surface of the clamper, a force of the clamper acting to grip the wire may be decreased, or a surface of the wire may be damaged by the scratches on the clamper due to the electrolytic corrosion. For this reason, it has been proposed to provide a clamper for electrical connection separately from the clamper for wire cutting (see, for example, Patent Literature 1).

CITATION LIST

Patent Literature

Technical Problem

However, in a conventional technology of the wire bonding apparatus described in Patent Literature 1, since secondary electrical discharges between a clamper for electrical connection and a wire cannot be inhibited, there is a problem in that electrolytic corrosion occurs on a surface of the clamper for electrical connection and this causes damage on a surface of the wire. Further, when a high voltage for forming a free air ball is not applied to the clamper for electrical connection, there is a problem in that an electrical connection between the wire and a non-bonding detection circuit cannot be secured and detection of non-bonding cannot be performed.

Therefore, it is an objective of the present invention to inhibit electrolytic corrosion of a wire clamper and to perform detection of non-bonding with a simple configuration.

Solution to Problem

A wire bonding apparatus of the present invention includes a spool, a clamper which grips a wire extended from the spool, a torch electrode which forms a free air ball at a front end of the wire by electrical discharges, a high-voltage power supply circuit which supplies power to the torch electrode, a non-bonding detection circuit which performs non-bonding detection between the wire and a device or the wire and a substrate, a first changeover switch which switches a connection between the spool and the high-voltage power supply circuit or the spool and the non-bonding detection circuit, a relay which turns on/off a connection between the clamper and the spool side of the first changeover switch, and a control part which sets the first changeover switch to the high-voltage power supply circuit side and turns off the relay to generate the electrical discharges, and sets the first changeover switch to the non-bonding detection circuit side and turns on the relay to perform the non-bonding detection.

In the wire bonding apparatus of the present invention, it is preferable that the wire bonding apparatus include a second changeover switch disposed between the spool side of the first changeover switch and the spool, and switching a connection between the spool side of the first changeover switch and a grounding wire, in which the control part performs a conduction confirmation of the spool by setting the first changeover switch to the non-bonding detection circuit side, turning on the relay, and setting the second changeover switch to the grounding wire side.

In the wire bonding apparatus of the present invention, it is preferable that the wire bonding apparatus include a wire guide disposed between the spool and the clamper and having a through hole with which at least a portion of the wire is in contact, and a connection wire connecting the wire guide and the spool side of the first changeover switch.

A circuit for a wire bonding apparatus of the present invention includes a high-voltage power supply circuit which supplies power to a torch electrode forming a free air ball at a front end of a wire by electrical discharges, a non-bonding detection circuit which performs non-bonding detection between the wire and a device or the wire and a substrate, a first changeover switch which switches a connection between a spool from which the wire extends and the high-voltage power supply circuit or the spool and the non-bonding detection circuit, a relay which turns on/off a connection between a clamper gripping the wire extended from the spool and the spool side of the first changeover switch, and a control part which sets the first changeover switch to the high-voltage power supply circuit side and turns off the relay to generate the electrical discharges, and sets the first changeover switch to the non-bonding detection circuit side and turns on the relay to perform the non-bonding detection.

A method of manufacturing a semiconductor device of the present invention includes processes as follows: preparing a wire bonding apparatus having a spool, a clamper which grips a wire extended from the spool, a torch electrode which forms a free air ball at a front end of the wire by electrical discharges, a high-voltage power supply circuit which supplies power to the torch electrode, a non-bonding detection circuit which performs non-bonding detection between the wire and a device or the wire and a substrate, a first changeover switch which switches a connection between the spool and the high-voltage power supply circuit or the spool and the non-bonding detection circuit, and a relay which turns on/off a connection between the clamper and the spool side of the first changeover switch; forming the free air ball by setting the first changeover switch to the high-voltage power supply circuit side and turning off the relay, and causing the high-voltage power supply circuit to supply power to the torch electrode; bonding the wire in which the free air ball is formed to a device or a substrate; and performing the non-bonding detection between the wire and the device or the wire and the substrate by setting the first changeover switch to the non-bonding detection circuit side and turning on the relay.

Advantageous Effects of Invention

According to the present invention, it is possible to inhibit electrolytic corrosion of the wire clamper and perform detection of non-bonding with a simple configuration.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a wire bonding apparatus100of the present embodiment will be described with reference to the drawings. As illustrated inFIG. 1, the wire bonding apparatus100includes a spool10, a clamper22, a torch electrode31, a high-voltage power supply circuit30, a non-bonding detection circuit40, a first changeover switch50, a relay53, and a control part60. InFIG. 1, a dashed-dotted line represents a signal wire. The same applies to other drawings.

The spool10includes a main body11on which a wire21is wound around a cylindrical portion having a flange provided at opposite ends of the cylindrical portion, a rotating shaft12connected to the main body11, a slip ring13attached to the rotating shaft12, and a terminal15provided at the flange of the main body11and to which an end portion16of the wire21wound around the cylindrical portion is connected. A motor14for rotationally driving the main body11is connected to the rotating shaft12.

The clamper22is attached between the spool10and a capillary23. The clamper22is opened and closed by an opening/closing drive part (not illustrated) to grip or release the wire21.

The torch electrode31is disposed in the vicinity of the wire21extended from a front end of the capillary23and generates electrical discharges between the front end of the wire21and the torch electrode31using power supplied from the high-voltage power supply circuit30to form a free air ball24at the front end of the wire21. The torch electrode31protrudes to the vicinity of the front end of the wire21when the free air ball24is formed, and is pulled back to a position away from the front end of the wire21in other cases.

The non-bonding detection circuit40applies a voltage to the wire21and detects that the wire21and a device19are connected to each other when the applied voltage decreases, and detects that the wire21and the device19on a substrate18connected to the ground are in a non-bonding (poor connection) state when the applied-voltage does not decrease while the voltage is applied to the wire21.

The first changeover switch50is configured with two relays including a high-voltage power supply circuit side relay51and a non-bonding detection circuit side relay52. When one of the two relays is turned on and the other thereof is turned off, a connection between the spool10and the high-voltage power supply circuit30or the spool10and the non-bonding detection circuit40is switched.

A plus side terminal of the high-voltage power supply circuit30is connected to the torch electrode31by a connection wire32. Also, a ground side terminal of the high-voltage power supply circuit30connected to the ground by an internal wiring34is connected to one end of the high-voltage power supply circuit side relay51by a connection wire33. The other end of the high-voltage power supply circuit side relay51is connected to the slip ring13of the spool10by a connection wire17. A terminal of the non-bonding detection circuit40is connected to one end of the non-bonding detection circuit side relay52by a connection wire41. The other end of the non-bonding detection circuit side relay52is connected to the connection wire17. The connection wire17and the clamper22are connected by a connection wire25, and are connected and released by the relay53.

The high-voltage power supply circuit30, the non-bonding detection circuit40, the clamper22, the high-voltage power supply circuit side relay51and the non-bonding detection circuit side relay52of the first changeover switch50, the relay53, and the motor14are connected to the control part60, and is configured to operate according to a command from the control part60. The control part60is a computer in which a central processing part (CPU)61for performing information processing or calculation and a memory62for storing control programs or control data are provided.

Further, the high-voltage power supply circuit30, the non-bonding detection circuit40, the first changeover switch50, the relay53, and the control part60constitute a circuit for a wire bonding apparatus (not illustrated).

Next, an operation of forming the free air ball24in the wire bonding apparatus100will be described with reference toFIG. 2. As illustrated inFIG. 2, the control part60turns on the high-voltage power supply circuit side relay51of the first changeover switch50and turns off the non-bonding detection circuit side relay52. Further, the control part60turns off the relay53to close the clamper22. Then, the control part60extends the torch electrode31to the vicinity of the front end of the wire21that has been extended from the front end of the capillary23, and a high voltage is applied from the high-voltage power supply circuit30to the torch electrode31as illustrated by arrows81and82inFIG. 2.

Electrical discharges are generated between the torch electrode31and the front end of the wire21by the applied high voltage, and the free air ball24is formed at the front end of the wire21. Further, a current flowing between the torch electrode31and the wire21due to the electrical discharges flows from the end portion16of the wire21wound around the main body11of the spool10to the terminal15as illustrated by arrows83and84inFIG. 2, and reaches the slip ring13through the rotating shaft12from the flange portion of the main body11as illustrated by an arrow85inFIG. 2. Then, the current flows from the slip ring13through the connection wire17and the high-voltage power supply circuit side relay51as illustrated by arrows85and86inFIG. 2, flows to the ground side terminal of the high-voltage power supply circuit30through the connection wire33as illustrated by arrows87to89inFIG. 2, and flows to the ground through the internal wiring34as illustrated by an arrow90.

Therefore, in the wire bonding apparatus100, no current flows between the clamper22and the wire21when the free air ball24is formed, and secondary electrical discharges between the clamper22and the wire21are not generated. Therefore, in the wire bonding apparatus100, occurrence of electrolytic corrosion of the clamper22can be inhibited.

Next, an operation of detecting non-bonding between the wire21and an electrode of the device19after bonding in the wire bonding apparatus100will be described with reference toFIG. 3. When the capillary23is lowered and the free air ball24is bonded to the electrode of the device19to form a crimped ball24a, it is in an open state as illustrated by a broken line inFIG. 3. Immediately after the bonding to the device19, the control part60turns off the high-voltage power supply circuit side relay51and turns on the non-bonding detection circuit side relay52in the first changeover switch50. Also, the control part60turns on the relay53. Then, the control part60applies a detection voltage from the non-bonding detection circuit40to the connection wire41. When the detection voltage is applied, a current flows from the non-bonding detection circuit side relay52to the slip ring13through the connection wire17as illustrated by arrows71to73inFIG. 3, passes from the slip ring13through the rotating shaft12and the terminal15, and flows from the end portion16of the wire21to the wire21wound around the main body11of the spool10as illustrated by an arrow74inFIG. 3. Then, the current passes through a straight portion of the wire21as illustrated by arrows75and76, and passes through the wire21that has extended from the front end of the capillary23to flow to the crimped ball24athat is bonded to the electrode of the device19as illustrated by an arrow77. Then, the current flows from the electrode of the device19to the ground.

When the wire21and the electrode of the device19are electrically connected, a current flows from the non-bonding detection circuit40to the ground with the route as described above, and the voltage applied from the non-bonding detection circuit40to the connection wire41is decreased. Then, the control part60determines that the wire21and the device19are satisfactorily connected when the voltage of the connection wire41is decreased, and, on the other hand, the control part60determines that the wire21and the device19have poor connection and non-bonding has occurred therebetween, and outputs a non-bonding detection signal when the applied voltage is not decreased.

Also, after the wire21is bonded to the substrate18after the crimped ball is formed, it is a state in which a tail wire21aillustrated by a dashed-dotted line inFIG. 3extends between the substrate18and the capillary23. The control part60closes the clamper22and pulls up the wire21to cut the tail wire21afrom the substrate18. Immediately before the cutting operation, the control part60applies the voltage from the non-bonding detection circuit40to the connection wire41to perform non-bonding detection between the substrate18and the wire21, as described above. In this state, since the clamper22has been closed, in addition to the route described above, a current flows also from the connection wire17to the clamper22through the relay53and the connection wire25, and thus the current flows to the wire21also from the clamper22as illustrated by arrows78and79inFIG. 3. As described above, the control part60determines that the wire21and the substrate18are satisfactorily connected when the voltage of the connection wire41is decreased, and, on the other hand, the control part60determines that the wire21and the substrate18have poor connection and non-bonding has occurred therebetween, and outputs a non-bonding detection signal when the applied voltage is not decreased.

As described above, in the wire bonding apparatus100of the present embodiment, since the free air ball24is formed by setting the first changeover switch50to the high-voltage power supply circuit side and turning off the relay53, and the non-bonding detection is performed by setting the first changeover switch50to the non-bonding detection circuit side and turning on the relay53, electrolytic corrosion of the clamper22is inhibited by preventing secondary electrical discharges between the clamper22and the wire21from being generated when the free air ball24is formed and the non-bonding detection between the wire21and the device19or the wire21and the substrate18can be performed. Further, according to the process as described above, the wire21is bonded to the device19on the substrate18or the substrate18while inhibiting electrolytic corrosion of the clamper22and performing the non-bonding detection between the wire21and the device19or the wire21and the substrate18, and thus a semiconductor device in which the device19and the substrate18are connected with the wire21can be manufactured.

Next, a wire bonding apparatus200according to another embodiment of the present invention will be described with reference toFIG. 4. Portions the same as those in the wire bonding apparatus100described above with reference toFIGS. 1 to 3are denoted by the same reference signs and description thereof will be omitted.

When the non-bonding detection between the device19and the wire is performed in the wire bonding apparatus100described above, a current passes through the spool10and flows from the wire21and the crimped ball24ato the ground due to a detection voltage applied from the non-bonding detection circuit40to the connection wire41. At this time, when electrical conduction of the slip ring13of the spool10is poor, the applied voltage is not decreased, and there is a likelihood of erroneous detection of non-bonding despite the fact that the wire21and the device19are connected. Therefore, as illustrated inFIG. 4, the wire bonding apparatus200of the present embodiment includes a second changeover switch54for switching the connection between the spool side of the first changeover switch50and a grounding wire55in the connection wire17of the wire bonding apparatus100described with reference toFIGS. 1 to 3so that a conduction confirmation of the slip ring13of the spool10can be performed. As illustrated inFIG. 4, the second changeover switch54is connected to a control part60and operates according to a command from the control part60. Thereby, the wire bonding apparatus200can distinguish between whether the cause of the applied voltage not decreasing is due to the non-bonding or poor electrical conduction of a slip ring13, and thereby erroneous detection of non-bonding can be inhibited and more reliable non-bonding detection can be performed.

An operation of performing a conduction confirmation of the slip ring13by the wire bonding apparatus200will be described with reference toFIG. 4. The control part60switches the second changeover switch54to the grounding wire55side to cause a connection wire17and the grounding wire55to have electrical conduction and to cut off electrical conduction between the connection wire17and a spool side of a high-voltage power supply circuit side relay51. Further, the control part60turns on a relay53and closes a clamper22.

The control part60applies a detection voltage from a non-bonding detection circuit40to a connection wire41similarly to the non-bonding detection operation described above. When the detection voltage is applied, a current flows from a non-bonding detection circuit side relay52to the clamper22through the connection wire17and the relay53as illustrated by arrows71,91,78, and79inFIG. 4. Then, the current flows from the clamper22to a wire21and from an end portion16of the wire21wound around a main body11of a spool10to a terminal15as illustrated by arrow83and84inFIG. 4, flows from the flange portion of the main body11through a rotating shaft12and from the slip ring13to the connection wire17as illustrated by an arrow85inFIG. 4, flows to the grounding wire55through the second changeover switch54as illustrated by an arrow92, and flows to the grounding wire55as illustrated by arrow93and94. When the slip ring13has electrical conduction similarly to the non-bonding detection described above, the current flows from the non-bonding detection circuit40to the ground with the route as described above, and the voltage applied from the non-bonding detection circuit40to the connection wire41is decreased. Then, when the voltage of the connection wire41is decreased, the control part60determines that electrical conduction of the slip ring13is normal. On the other hand, when the applied voltage is not decreased, it is determined that the electrical conduction of the slip ring13is poor, and a signal of poor electrical conduction of the slip ring13is output.

As described above, the wire bonding apparatus200of the present embodiment can determine whether the cause of the applied voltage not decreasing is due to the non-bonding or poor electrical conduction of the slip ring13in addition to obtaining the same effects as in the wire bonding apparatus100described above, and thereby erroneous detection of non-bonding can be inhibited and more reliable non-bonding detection can be performed.

Next, a wire bonding apparatus300according to another embodiment will be described with reference toFIG. 5. Portions the same as those in the wire bonding apparatus100and the wire bonding apparatus200described above with reference toFIGS. 1 to 4are denoted by the same reference signs and description thereof will be omitted. In the wire bonding apparatus300, a wire guide56and a connection wire57are added to the wire bonding apparatus200described above with reference toFIG. 4.

The wire guide56is disposed between a spool10and a clamper22and has a through hole with which at least a portion of a wire21is in contact. The wire guide56is made of a metal. The wire guide56may be a blow-up portion that applies an upward tension to the wire21by blowing air to the through hole from a lower side thereof. The wire guide56is connected to the spool side of a first changeover switch50by the connection wire57.

A conduction confirmation of the slip ring13in the wire bonding apparatus300will be described. A current from a non-bonding detection circuit40flows from the spool side of the first changeover switch50to the wire guide56through a connection wire17as illustrated by arrows95and96inFIG. 5. Since the wire guide56is in contact with the wire21, the current flows from the wire guide56to the wire21and flows from the spool10to the ground through a grounding wire55as described above with reference toFIG. 4. Therefore, the wire bonding apparatus300can perform the conduction confirmation of the slip ring13even when the clamper22is in an open state.

As described above, since the wire bonding apparatus300of the present embodiment can perform a conduction confirmation of the slip ring13more reliably than that in the wire bonding apparatus200described above, erroneous detection of non-bonding can be more reliably inhibited, and thus more reliable non-bonding detection can be performed.