JP3257879B2 - Bonding wire short circuit detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for an electronic device in which electrodes of various chips mounted on a substrate and electrodes on the substrate are connected by wires, and more particularly to another conductor pattern formed on the substrate. The present invention relates to a bonding wire short-circuit detecting device that detects a short circuit between a wire and a wire.

For example, a surface acoustic wave device is composed of a substrate made of an insulator and a chip of a surface acoustic wave element mounted on the substrate, and an electrode on the chip and an electrode formed on a chip mounting surface of the substrate. Are usually connected via a bonding wire.

[0003] The substrate has a plurality of electrodes for bonding wires to the chip mounting surface and a conductor pattern for connecting between the electrodes, and the bonded wire and the conductor pattern for connecting between the other electrodes. It is often formed so as to intersect with a space.

However, in devices requiring high-density mounting, the outer diameter of the substrate is restricted irrespective of the size of a chip mounted thereon, and a conductor pattern crossing the vicinity of an electrode and a wire bonded to the electrode are provided. Cannot be provided with a sufficient gap.

[0005] In addition, the characteristics of the surface acoustic wave device are deteriorated when the resin adheres to the chip, so that the wire cannot be fixed by applying the resin. As a result, various short circuits occur from an instantaneous short circuit to a permanent short circuit between the unconnected wire and the conductor pattern.

Therefore, there is a demand for the development of a bonding wire short-circuit detecting device capable of detecting a short circuit from a momentary short circuit to a permanent short circuit.

[0007]

2. Description of the Related Art FIG. 3 is a perspective view showing an appearance of a target surface acoustic wave device, and FIG. 4 is a principle view showing a conventional bonding wire short-circuit detecting method.

As shown in FIG. 3, the surface acoustic wave device 1 comprises an insulating substrate 11 and a chip 12 of a surface acoustic wave device mounted on the substrate 11, and the electrode 13 of the chip 12 and the chip mounting surface of the substrate 11 are provided. Bonding wire between the formed electrode 14
Connected via 15.

The substrate 11 has a plurality of electrodes 14 for bonding wires 15 to the chip mounting surface and a conductor pattern 16 for internally connecting the electrodes 14, and the conductor pattern 16 for internally connecting the bonded wires 15 to the electrodes. It is often formed to intersect via a space.

However, in a device requiring high-density mounting, the outer diameter of the substrate 11 is restricted irrespective of the size of the chip 12 mounted thereon, and the conductor pattern crossing the vicinity of the electrode 14.
The gap provided between the wire 16 and the wire 15 bonded to the electrode 14 may be insufficient.

The surface acoustic wave device 1 configured to obtain predetermined characteristics by generating an elastic wave on the surface of the chip 12 has, for example, resonance characteristics and the like when a hardening resin or the like adheres to the chip 12. Therefore, the wire cannot be fixed by applying the resin.

In such a surface acoustic wave device 1, when the wire 15 moves, it may come into contact with an adjacent conductor pattern 16 to cause a short circuit. Therefore, the presence or absence of a short circuit between the wire 15 and the conductor pattern 16 is inspected for all the surface acoustic wave devices that have been assembled.

A conventional detection method for detecting a short-circuit of a bonding wire comprises a test power supply 21, an ammeter 22, a voltmeter 23, etc., between two electrodes 14 which are not internally connected as shown in FIG. The detected short circuit detecting device 2 is connected, and the presence or absence of a short circuit is detected from a change in the current value.

That is, the chip 12 of the surface acoustic wave element has a plurality of independent conductive patterns formed on an insulating substrate, and each conductive pattern is provided with a separate electrode 13.
When not connected internally because it is connected to the electrode
There is no conduction between the fourteen.

In other words, the wire 15 and the conductor pattern 16
If there is no short circuit, connect the short-circuit detection device 2 as shown in FIG.
As shown by the solid line, a current for charging a capacitive load initially flows, and then rapidly attenuates to an extremely weak current value flowing through an insulation resistance or the like.

When a short circuit occurs between the wire 15 and the conductor pattern 16, a short circuit detecting device 2 is connected to the circuit shown in FIG.
As shown by a broken line, a large current flows through the wire 15 and the conductor pattern 16, so that a short circuit therebetween can be easily detected.

[0017]

However, in the case of a short circuit in which the wire 15 is slightly in contact with the conductor pattern 16 because the wire 15 is extremely thin and easily movable, a current flows immediately after the short circuit detecting device 2 is connected. However, there is a case where the wire 15 is temporarily separated from the conductor pattern 16 due to the impact of energization.

That is, an instantaneous short-circuit occurs, and a current flows instantaneously immediately after the short-circuit detecting device 2 is connected, as indicated by a dashed line in FIG. 4 (b). Such a change in current is similar to a case where there is no short circuit indicated by a solid line, and there is a problem that it is easy to overlook in the conventional short circuit detection method.

An object of the present invention is to provide a bonding wire short-circuit detecting device capable of detecting a short circuit from a momentary short circuit to a permanent short circuit.

[0020]

FIG. 1 is a block diagram showing a short-circuit detecting device according to the present invention. The same object is denoted by the same symbol throughout the drawings.

An object of the present invention is to detect a short circuit between a bonding wire and another conductor pattern on a substrate of a component to be inspected in which an electrode on a chip and an electrode on a substrate are connected by a bonding wire. A voltage application circuit that applies a test voltage between the bonding wire and the conductor pattern of the device under test, a conversion circuit that converts at least a change in current flowing through the bonding wire and the conductor pattern into a voltage change, and an output voltage of the conversion circuit. a comparator configured to output signal level exceeds the reference voltage value is inverted, and a holding circuit configured to store an output signal level of the comparator until a reset signal is input comprises a reference
The voltage value indicates that the bonding wire and the conductor pattern are short-circuited
If not, apply a capacitive load immediately after applying the test voltage.
Between the bonding wire and the conductor pattern to
Is higher than the value obtained by converting the current flowing through
And the bonding wire and the conductor pattern are instantaneous
Bonding wire and conductor pattern in case of short circuit
Is lower than the value obtained by converting the current flowing between
Is set to a value, when inspection of the inspected part, the holding circuit
The stored comparator output signal level is
When the output level is inverted by the
Momentary or permanent gap between wire and conductor pattern
It is attained by a bonding wire short-circuit detecting device, characterized in that it is determined that a short-circuit has occurred .

[0022]

The change of the current indicated by the solid line in FIG. 4B is similar to the pattern of the change of the current indicated by the alternate long and short dash line, but the peak of the current is different. Therefore, as shown in FIG. 1, a voltage application circuit for applying a test voltage between a bonding wire and a conductor pattern of a component to be inspected, and a conversion circuit for converting at least a change in current flowing through the bonding wire and the conductor pattern into a voltage change. A comparator configured to invert an output signal level when an output voltage of the conversion circuit exceeds a reference voltage value, and a holding circuit configured to store the output signal level of the comparator until a reset signal is input. The reference voltage value is determined by the bonding wire and conductor pattern.
Capacitor immediately after the test voltage is applied if the
Wire and conductor pattern to charge the load
The value of the current flowing between the
High value, bonding wire and conductor pattern
Connection with the bonding wire when the
The value obtained by converting the current flowing between the body pattern and the body to a voltage
Is set to a value lower than, when inspection of the inspected part,
If the output signal level of the comparator stored in the holding circuit is
When the output level is inverted by the comparator,
The gap between the bonding wire and the conductor pattern is instantaneous or
Or it is determined that there is a permanent short circuit. That is, it is possible to realize a bonding wire short-circuit detecting device capable of detecting a short circuit from a momentary short circuit to a permanent short circuit.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a block diagram showing one embodiment of the short-circuit detection device according to the present invention.

As shown in FIG. 1, the short-circuit detecting device according to the present invention comprises a voltage application circuit 3 connected to the component 1 to be inspected at the time of inspection. When a switch 32 is turned on, a test power supply 31 is connected and the bonding wire 15 is connected. Or conductor pattern 16
Is applied with a predetermined voltage.

If there is no short circuit between the wire 15 and the conductor pattern 16, when the test power supply 31 is connected, as in the case of the conventional apparatus, as shown in FIG.
As shown by the solid line, a current for charging a capacitive load initially flows, and then rapidly attenuates to an extremely weak current value flowing through an insulation resistance or the like.

If an instantaneous or permanent short circuit occurs between the wire 15 and the conductor pattern 16, the test power supply 31
Is connected, a large current flows into the circuit of the detecting device via the wire 15 and the conductor pattern 16 as shown by a broken line or a dashed line in FIG.

The short-circuit detecting device also includes a conversion circuit 4 connected to the bonding wire 15 or the conductor pattern 16 of the component 1 to be inspected. At 4 it is converted to a change in voltage.

As shown in FIG. 4 (b), the current change when there is no short circuit and the current change when there is a short circuit have different peak values, and the peak value of each current change is the middle of both peak values. By comparing with a reference value corresponding to the level, it is possible to determine the presence or absence of a short circuit.

Therefore, a reference power supply 51 for inputting a reference voltage for judging the presence or absence of a short circuit and the conversion circuit 4 are connected to the input side of the comparator 5, and when the output voltage of the conversion circuit 4 exceeds the reference voltage value, the conversion of the comparator 5 is started. The output signal level is configured to be inverted.

The comparator 5 has a holding circuit 6 for storing and holding the output signal level of the comparator 5 until reset.
For example, when the test power supply 31 is connected as in the case of an instantaneous short circuit, it is also possible to detect a current that flows instantaneously and then shuts off.

Referring to FIG. 2, in one embodiment of the present invention, the voltage application circuit 3 has a filter 33 and an electromagnetic relay 34 in addition to the test power supply 31 and the switch 32. When the switch 32 is turned on, the contact 35 of the electromagnetic relay 34 is turned on. The test power supply 31 is closed and the test power supply 31 is connected to the component under test 1 via the protection resistor 36.

In such a detection device, the chattering of the switch 32 is filtered out because chattering is
Absorption by 33 and chattering at the contact 35 are prevented by using, for example, a Mercury relay as the electromagnetic relay 34.

As a means for preventing noise from being superimposed on the signal, the conversion circuit 4 connected to the component under test 1 via the shield line 7 is an amplifying circuit for amplifying the current input through the protection resistor 41. 42 and a resistor 43 for converting a change in current into a change in voltage.

The input side of the comparator 5 is connected to a reference power supply 51 which can arbitrarily set a reference voltage for judging the presence or absence of a short circuit and the conversion circuit 4. When the output voltage value of the conversion circuit 4 exceeds the reference voltage value, the comparator 5 Is configured to invert the output signal level of.

The holding circuit 6 is composed of an FF circuit which outputs a signal when the output signal level of the comparator 5 is inverted and rises. When the switch 32 of the voltage applying circuit 3 is turned on at the time of inspection, the electromagnetic relay 34 operates. It is reset before the contact 35 is closed.

That is, when the switch 32 is turned on, a pulse is generated by the differentiating circuit composed of the resistor 61 and the capacitor 62 and the two inverters 63, and the pulse of the comparator 5 previously stored and retained in the retaining circuit 6 composed of the FF circuit is obtained. The output signal level is reset.

When the switch 32 is turned on, the electromagnetic relay 34 operates and the contact 35 is closed, but there is a time lag between the operation of the holding circuit 6 and the next time before the output signal level of the previous comparator 5 is reset. The output signal level is not input to the holding circuit 6.

As a means for preventing noise from being superimposed on the signal, the conversion circuit 4 is connected to the component 1 to be inspected via the shield wire 7, but the shield wire 7 composed of the core wire 71 and the shield 72 has a capacitance component. Then, the pulse signal generated in the component under test 1 is absorbed by the capacitance component.

Therefore, a compensating circuit 8 for equalizing the potentials of the core wire 71 and the shield 72 and canceling out the capacitance component of the shielded wire 7 is added to the conversion circuit 4. It has resistors 82 and 83 equal to resistors 41 and 43.

[0040] and converting circuit for converting a voltage application circuit for applying a test voltage between the bonding wire and the conductor pattern of the thus parts for inspection, a change in the current flowing through the at least bonding wires and the conductor pattern to the change in voltage,
A comparator configured to invert an output signal level when an output voltage of the conversion circuit exceeds a reference voltage value, and a holding circuit configured to store the output signal level of the comparator until a reset signal is input, Reference voltage
The value indicates that the bonding wire and the conductor pattern
If not, charge the capacitive load immediately after applying the test voltage.
Flow between the bonding wire and the conductor pattern
Is higher than the value obtained by converting the current value
And the bonding wire and conductor pattern are instantaneous
Bonding wire and conductor pattern
Value that is lower than the value obtained by converting the current flowing between
Is set in the holding circuit when inspecting the part to be inspected.
The output signal level of the comparator
When the output level is inverted by
Momentary or permanent gap between wire and conductor pattern
It is determined that a short circuit has occurred. That is, it is possible to realize a bonding wire short-circuit detecting device capable of detecting a short circuit from a momentary short circuit to a permanent short circuit.

[0041]

As described above, according to the present invention, it is possible to provide a bonding wire short-circuit detecting device capable of detecting an instantaneous short-circuit to a permanent short-circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a short-circuit detection device according to the present invention.

FIG. 2 is a block diagram showing one embodiment of a short-circuit detection device according to the present invention.

FIG. 3 is a perspective view showing an appearance of a target surface acoustic wave device.

FIG. 4 is a principle view showing a conventional bonding wire short-circuit detection method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Component to be inspected 3 Voltage application circuit 4 Conversion circuit 5 Comparator 6 Holding circuit 7 Shield wire 8 Compensation circuit 11 Board 12 Chip 13, 14 Electrode 15 Bonding wire 16 Conductor pattern 31 Test power supply 32 Switch 33 Filter 34 Electromagnetic relay 35 Contact 36, 41 Protection resistor 42 Amplification circuit 43, 61, 82, 83 Resistance, 51 Reference power supply 62 Capacitor 63 Inverter 71 Core wire 72 Shield 81 Amplification circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/66 H01L 21/60 321

Claims (2)

(57) [Claims] An electrode (13) on a chip (12) and an electrode (14) on a substrate (11) are connected to a bonding wire (1).
5) A device for detecting a short circuit between the bonding wire (15) and another conductor pattern (16) on the substrate (11) of the component under test (1) connected by 5), a voltage applying circuit for applying a test voltage between said bonding wires (15) and <br/> conductor pattern of the inspection part (1) (16) (3), at least said bonding wire (15) and the conductor A conversion circuit (4) for converting a change in current flowing through the pattern (16) into a voltage change, and a comparator (4) configured to invert the output signal level when the output voltage of the conversion circuit (4) exceeds a reference voltage value. 5); and a holding circuit (6) configured to store the output signal level of the comparator (5) until a reset signal is input, wherein the reference voltage value is determined by the bonding wire (15) and the bonding wire (15). Guidance
Test voltage when body pattern (16) is not short-circuited
The bond is used to charge a capacitive load immediately after application.
Between the wire (15) and the conductor pattern (16).
Is higher than the value obtained by converting the current value
And the bonding wire (15) and the conductor pattern
Bonding (16) is short-circuited momentarily
Flow between the wire (15) and the conductor pattern (16)
Current value is set to a value lower than the converted value.
In the inspection of the part (1) to be inspected, it is stored in the holding circuit.
The output signal level of the comparator
When the output level is inverted by (5),
Between the wiring wire (15) and the conductor pattern (16).
Is determined to be short-circuited momentarily or permanently . 2. A component (1) to be inspected and a conversion circuit (4) are connected by a shield wire (7) comprising a core wire (71) and a shield (72), and the core wire (71) and the shield (72) are connected. 2. The bonding wire short-circuit detecting device according to claim 1, further comprising a compensating circuit for equalizing the potential of the shield wire and canceling out the capacitance component of the shield wire, thereby preventing the extinction of the minute current pulse due to the capacitance component.