KR20050043258A - Wire boding machine - Google Patents

Abstract

The wire bonding device according to the present invention comprises: a bonding monitor unit for converting whether a wire is attached to a bonding surface into an electrical signal and outputting it as a non-stick signal; A logic controller configured to generate a wire clamp containment / opening signal in response to the non-stick signal; And a wire clamp control unit for controlling the wire clamp in response to the wire clamp close / open signal. According to the wire bonding apparatus which concerns on this invention, there exist the following effects. First, it is possible to prevent the wire from leaving after bonding. Therefore, the work convenience and production efficiency (UPH, unit per hour) are improved in the wire bonding process. Second, by checking whether the wire tail of the proper length is formed, it is possible to predict whether the proper ball can be formed.

Description

Wire bonding machine {Wire boding machine}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wire bonding devices, and more particularly to wire bonding devices for preventing wire detachment.

The wire bonding process is a process of joining and connecting a conductive medium such as high purity gold wire with ultrasonic waves and heat by a capillary between a pad provided on an upper surface of a die and a lead of a lead frame.

1A to 1H are sequential schematic diagrams of a wire bonding process.

Referring to FIG. 1A, after the capillary 100 is mounted to the bonder, the capillary 100 is placed directly on the chip pad 108. When the clamp 104 is opened, the capillary 100 moves downward. When a free air ball (FAB) 106 is formed on a wire tail of an elector flame off (EFO) located next to the capillary 100, the FAB ball 106 is formed by a chamfer discharge. Such ball shape is maintained.

Referring to FIG. 1B, the FAB 106 in the chamfer performs primary bonding on the chip pad 108, which is the first bonding surface, by the heat, ultrasonic wave, and proper bonding force of the capillary 100.

Referring to FIG. 1C, after primary bonding, the capillary 100 moves up to a position forming a loop, wherein the wire is capillary 100 to provide a length sufficient to form the loop. Move along.

Referring to FIG. 1D, when the capillary 100 moves to the secondary bonding position, the wire forms a loop in this process.

Referring to FIG. 1E, the capillary 100 performs the second bonding while closely attaching the wire to the lead 110, which is the second bonding surface, by heat, ultrasonic waves, and proper bonding force. The second bonding performs stitch bonding on the one hand and tail bonding on the other hand.

Referring to FIG. 1F, as the capillary 100 rises up from the second bonding surface 110 after the second bonding, a wire tail 112 of a predetermined length is exposed under the capillary 100.

Referring to FIG. 1G, when the wire clamp 104 is closed after the capillary 100 rises for a predetermined period of time, the wire tail 112 of the predetermined length is separated from the second bonding surface 110.

Referring to FIG. 1H, wire tail 112 is melted by an electrical spark to form FAB 106 for subsequent bonding.

In this wire bonding process, the wire breakout is XY homing during EFO (Electro Flame-Off) discharge, before the wire clamp 104 is closed after the second bonding, i.e., in the period between FIGS. 1F and 1G. It is caused by various factors such as poems. This occurs when the wire tension and the air guide is operating when the wire is separated so that the wire exits the capillary 100.

If the wire exits the capillary, it may be necessary to reseat the wire into the capillary to create a ball. As a result, in the wire bonding process, work convenience and production efficiency (UPH, unit per hour) are reduced.

In addition, in steps 1G and 1H, if the length of the wire tail 112 is too short or long, an appropriate ball 106 is not formed, resulting in an error in the next bonding process. Therefore, in order to form the appropriate FAB 106, the wire tail 112 of the proper length should be formed after the second bonding.

Accordingly, an aspect of the present invention is to provide a wire bonding device that performs a wire departure prevention function.

In addition, another technical problem to be achieved by the present invention is to provide a wire bonding device for forming a wire tail of an appropriate length, in order to form an appropriate ball.

According to an aspect of the present invention, there is provided a wire bonding device including: a bonding monitor unit configured to convert an electrical signal from a wire to a bonding surface, and output the electrical signal as a non-stick signal; A logic controller configured to generate a wire clamp containment / opening signal in response to the nonstick signal; And a wire clamp control unit for controlling the wire clamp in response to the wire clamp closing / opening signal.

According to another aspect of the present invention, there is provided a wire bonding device, which converts whether a wire is attached to a bonding surface into an electrical monitor signal, and outputs the electrical monitor signal, and generates a count start signal when the capillary falls from the bonding surface. Bonding monitor unit; A logic controller for outputting, as a non-stick signal, whether or not a wire is attached to a bonding surface in response to the electrical monitor signal; A counter enabled for the count start signal and disabled for the non-stick signal to perform a count operation and output a result; And a central processing unit that calculates a wire tail length by reading the count result after generating the non-stick signal.

Hereinafter, with reference to the accompanying drawings the configuration and operation of the wire bonding device according to a preferred embodiment of the present invention will be described in detail as follows. Like reference numerals in the drawings denote components that perform the same function.

The basic concept of the wire bonding method according to the present invention is, firstly, if an error signal for predicting wire breakout occurs, a command is generated by the hardware to hold the wire clamp, so that the wire clamp closes the clamp before the wire breaks off. .

The basic concept of the wire bonding method according to the present invention is to determine whether the FAB can be normally formed by measuring the length of the tail formed after the second wire bonding.

2 is a capillary position (Z) graph according to time after the second bonding, for explaining the wire clamp control operation.

3 is a schematic block diagram of a conventional wire bonding device for the wire clamp control operation of FIG.

In FIG. 3, the NSOL determination unit 300 converts the non-stick on lead from the wire tail 112 to the bonding surface 110 into an electrical signal by a load or a conduction current.

The VME (Versa Modulo Euto) dedicated processing unit 302 periodically checks the NSOL determination circuit 300 by the interrupt 304 to detect a non-stick signal 306. . The non-stick signal 306 is a signal detected when the second bonding wire 112 is separated from the second bonding surface 110.

Referring to Fig. 2, conventionally, the wire clamp 104 is closed after the time point t4 detected by the interrupt 304, regardless of the time point at which the non-stick actually occurred. In this case, when the interrupt period Δt is large or the interrupt rank is delayed by another CPU process, the time t4 at which the non-stick signal is detected is further delayed. Because of this, there is a high risk that the wire will escape from the capillary before the wire clamp is closed after the actual non-stick has occurred.

4 is a block diagram illustrating a wire bonding device according to an embodiment of the present invention. 5 is a timing diagram of a control signal for wire clamp control by the apparatus of FIG.

In the embodiment of Fig. 4, when an error signal detecting a wire break occurs, a command is generated by the hardware to hold the wire clamp, and immediately the wire clamp closes the clamp before the wire breaks off.

At the time t1 during the second bonding, the wire break prevention signal is started internally by the wire clamp control unit 408. Here, since the wire departure prevention signal illustrated in FIG. 5 corresponds to a signal inside the CPU, it may not be exposed to the outside during the actual implementation.

The bonding monitor 400 monitors a contact state between the second bonding wire 112 and the second bonding surface 110, converts the electrical signal into an electrical signal, and outputs the non-stick signal 402.

After the time point t2, when the second bonding ends and the capillary rises, if the non-stick signal 402 is detected by the logic controller 404 at time t3, the wire clamp close signal 406 is generated at time t4. At time t5 after the time t4, the wire break signal is cleared.

After the wire tail break is detected at time t6, a wire clamp open signal 406 is generated at time t7. The wire clamp close / open signal 406 may be directly connected to the wire clamp amplifier 414 by passing the CPU 408 shown in the figure. The wire clamp close / open signal 406 may also serve as a command to generate the wire clamp signal 410 first and foremost to the wire clamp control unit 408.

Here, the wire clamp controller 408 may be configured as a chip separate from the logic controller 404 when implemented in an actual circuit. However, the wire clamp control unit 408 may be implemented to be integrated into the logic control unit 404 in its function.

As a result, when the capillary rises to the wire tail disconnected position, if a wire deviation occurs, a non-stick signal is immediately generated, thereby immediately generating a wire clamp clamp signal, so that the wire tensioner and the air guide The wire does not break out of the capillary even if it is in operation.

Hereinafter, in order to form an appropriate FAB, a wire bonding method for forming a wire tail of an appropriate length and a wire bonding apparatus to which the same is described will be described with reference to the drawings.

Conventionally, in order to determine whether the length of the formed wire tail 112 can form an appropriate FAB 106, a nonstick signal is measured several times in a period between FIGS. 1E to 1G to indirectly connect the wire. The method of estimating the length of the tail was used. However, this indirect wire tail measurement method may be inaccurate due to the following factors.

The first cause of inaccurate measurements is the incorrect timing of reading the nonstick signal. In general, the non-stick signal measuring unit is composed of a separate module from the Z-axis controller in the capillary rising and falling directions, and periodically monitors the non-stick signal by an interrupt. Therefore, it is difficult to synchronize the capillary Z-axis position with the non-stick signal measurement time point, and an error of the maximum interrupt period may occur.

A second factor of inaccurate measurement is that the wire is pulled upward by the wire tensioner and the wire guide so that it is forced up at the moment the wire tail breaks. However, the wire clamp 104 is closed at a time point T7 after the time point T6 at which the wire tail is broken. Therefore, the amount of the wire rising from the time point T6 at which the wire tail is broken to the time point T7 at which the wire clamp 104 is closed remains unknown.

Therefore, in order to accurately measure the wire tail length, the following two things must be satisfied.

First, the nonstick signal must be measured accurately.

Secondly, the wire is prevented from being pulled up after the wire tail is broken to maintain the tail length at the moment T6 when the wire tail is broken.

6 is a block diagram illustrating an embodiment of a wire bonding device according to another embodiment of the present invention.

FIG. 7 is a timing diagram and capillary Z-axis and time of signals of the apparatus shown in FIG. 6.

Referring to FIG. 6, first, a separate timer or counter 620 is provided for accurate non-stick signal measurement.

6 and 7, the bonding monitor unit 600 converts the wires to the second bonding surface 110 and outputs the non-stick signals 602. The bonding monitor 600 determines whether the wire tail 112 is broken by converting a load applied to the second bonding surface 110 into an electrical signal or measuring a current of the second bonding surface 110. Convert to an electrical signal. In addition, the bonding monitor unit 600 also generates a start signal 622 of the counter 620 at the time t1 of the capillary 100 rising after the second bonding.

The counter 620 is enabled by the counter start signal 622 and is disabled by the nonstick signal 602 to perform a count operation from the start time t1 to the time point t2 at which the nonstick signal 602 is generated. .

Thereafter, after the time t3 at which the wire tail 112 is broken (t4), the wire clamp control unit 608 generates a counter 620 read signal 626 to read the count data 624 from the counter 620. come. Using the count data 624 read, the wire clamp control unit 608 calculates the wire tail length with respect to the capillary 100 rising speed.

The wire clamp control unit 608 also generates a wire clamp close signal 610 immediately after the non-stick signal 602 is generated. The wire clamp amplifier 614 closes the wire clamp 104 in response to the close signal 610.

As a result, since the wire tail 112 is disconnected and the non-stick signal 602 is generated, and the non-stick signal 602 is generated and the wire clamp is closed, there is no change in the wire tail length.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the wire bonding device according to the present invention has the following effects.

First, it is possible to prevent the wire from leaving after bonding. Therefore, the work convenience and production efficiency (UPH, unit per hour) are improved in the wire bonding process.

Second, by checking whether the wire tail of the proper length is formed, it is possible to predict whether the proper ball can be formed.

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

1A to 1H are sequential schematic diagrams of a wire bonding process.

2 is a capillary position (Z) graph according to time after the second bonding, for explaining the wire clamp control operation.

3 is a schematic block diagram of a conventional wire bonding device for the wire clamp control operation of FIG.

4 is a block diagram illustrating a wire bonding device according to an embodiment of the present invention.

5 is a timing diagram of a control signal for wire clamp control by the apparatus of FIG.

6 is a block diagram illustrating an embodiment of a wire bonding device according to another embodiment of the present invention.

FIG. 7 is a graph of the timing and capillary Z-axis and time of the signals of the device shown in FIG. 6.

Claims (2)

A bonding monitor unit converting whether or not the wire is attached to the bonding surface into an electrical signal and outputting the non-stick signal; A logic controller configured to generate a wire clamp containment / opening signal in response to the nonstick signal; And And a wire clamp control unit for controlling the wire clamp in response to the wire clamp close / open signal. A bonding monitor unit converting whether the wire is attached to the bonding surface and outputting the electrical signal as a non-stick signal, and generating a count start signal when the capillary falls from the bonding surface; A counter enabled for the count start signal and disabled for the non-stick signal to perform a count operation and output a result; And And a wire clamp control unit for calculating a wire tail length by reading the count result after generating the non-stick signal.