JPH03183141A - Wire bonding apparatus - Google Patents

Abstract

PURPOSE:To automatically form a ball again without stopping the operation of an apparatus when a ball formation operation has failed and to execute a bonding operation by a method wherein, when a detector detects the abnormality of the ball formation operation, the relative position between the tip of a wire and a wire heating source is made closer and the relative position is set again in order to execute the ball formation operation again. CONSTITUTION:A ball diameter becomes too small, the amount of eccentricity of the ball center line becomes too large and so on by a bad influence such as a bend, an irregularity in a length or the like of a wire 32. When a detector detects this abnormality, a control apparatus 19 brings the relative position between the tip of the wire 32 and a wire heating source close to the relative position for a ball formation operation at this time. In a reset state to execute the ball formation operation again, a torch electrode 25 heats an abnormal ball again. At this reheating operation, the relative position between the tip of the wire 32 and the torch electrode 25 is made closer as compared with an initial heating operation; as a result, an optimum ball in which the ball diameter and the amount of eccentricity of the ball center line have been improved can be formed again by the reheating operation. Thereby, a bonding operation whose reliability is high can be executed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a wire bonding device.

[Prior Art] As shown in FIG. 6, in a wire bonding apparatus, the tip of a wire 2 protruding from a capillary 1 and a torch electrode 3 are set at relative positions for forming a ball, and an electric torch is used. A torch electrode 3 controlled by a unit 4 discharges and heats the tip of the wire 2 to form a ball at the tip of the wire 2. Then, using the ball of the wire 2, the wire is joined to the part to be joined (the electrode of the IC pellet and the lead of the lead frame).

The above-mentioned ball is used to suitably join the wire 2, but the premise is that the diameter of the ball is appropriate for the wire diameter of the wire 2, and that the eccentricity of the ball center line with respect to the ring line of the wire 2 is appropriate. There is a need to. Thereby, the wire 2 can be joined to the electrode of the part to be joined with high reliability.

[Problems to be Solved by the Invention] However, when forming the above-mentioned ball, the wire 2 protruding from the capillary 1 is bent, the length is uneven, and other negative effects occur, making it difficult to determine the appropriate diameter of the ball and the center line of the ball. If the eccentricity of the ball is not correct, the ball may not be formed properly and the ball may fail.

If ball formation fails, stop the operation of the device, have the operator correct the wire 2 to the proper straightness, and discharge around the abnormal ball again, or discard the abnormal ball by manual operation of the operator. Complicated operations are required to recover from abnormalities, such as performing new bonding after bonding.

Furthermore, as described in Japanese Patent Publication No. 61-11464, it is also conceivable that when an abnormal ball is formed, the electric discharge is automatically re-discharged around the abnormal ball. However, since the relative position between the tip of the wire and the torch electrode is the same during the initial discharge and during the re-discharge, the re-discharge does not necessarily result in normal ball formation.

An object of the present invention is to automatically re-form the ball without stopping the operation of the device when a ball formation fails, to always obtain a proper ball and to perform highly reliable bonding.

[Means for Solving the Problems] The present invention sets the tip of a wire and a heating source of the wire at relative positions for forming a ball, heats the tip of the wire with the wire heating source, and heats the tip of the wire. A wire bonding device that forms a ball at the tip is equipped with a detector that detects the state of ball formation due to the wire heating source, and if the detector detects an abnormality in the current ball formation, the wire bonding device The relative position with respect to the source is reset to a relative position for re-forming the ball that is closer than the relative position for forming the ball this time, and the tip of the wire is reheated by the wire heating source to re-form the ball. The system is equipped with a control device that allows the test to be carried out.

[Operation] In the present invention, during normal bonding work, the tip of the wire and the wire heating source are set at relative positions for forming a ball, the ball is formed, and the bonding work is continued.

On the other hand, on the condition that due to adverse effects such as bending of the wire or variations in length, the ball diameter is too small or the eccentricity of the ball center line is too large due to the current ball formation, and the detector detects this abnormality, The control device brings the relative position between the tip of the wire and the wire heating source closer than the relative position for forming the current ball. Then, under this reset state for ball reformation, the wire heating source reheats the abnormal ball. During this reheating, the relative position between the tip of the wire and the wire heating source is brought closer than during the initial heating, so reheating regenerates a proper ball with improved ball diameter and eccentricity of the ball center line. It will be possible. Thereby, highly reliable bonding can be performed.

That is, according to the present invention, when ball formation fails, the ball is automatically re-formed without stopping the operation of the apparatus, and it is possible to always obtain a proper ball and perform highly reliable bonding.

[Example] Fig. 1 is a schematic diagram showing a wire bonding device according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing the main part of Fig. 1,
Figure 3 is a schematic diagram showing the capillary drive section in Figure 2;
The figure is a schematic diagram showing the torch drive unit in Figure 2, and Figure 5 is a schematic diagram showing the torch drive unit in Figure 2.
It is a sectional view along the vV line of a figure.

As shown in FIG. 2, the bonding apparatus 10 includes a bonding head 12 installed on an XY table 11, an arm 13 swingably attached to the bonding head 12, and a capillary 14 detachably attached to the tip of the arm 13. are doing.

At the base end of the arm 13, as shown in FIG.
A pair of parallel plates 15 are provided, and a pin 18 protruding from a rotary plate 17 rotated by the drive of a motor 16 is positioned between the parallel plates 15. This allows motor 1
By controlling the amount and direction of rotation of arm 13 and capillary 14 with a control device F19, which will be described later, the amount of movement of arm 13 and capillary 14 can be digitally set.

Bonding equipment? In frame 21 of &10, Fig. 4,
As shown in FIG. 5, the seeding lever 23 is
A support shaft 23A is rotatably supported, and a torch rod 24 is fixed to the tip of the swing lever 23. torch stick 2
A torch electrode 25 is provided at the tip of 4.

A solenoid 26 and a tension spring 27 are arranged on both sides of the swing lever 23 across the support shaft 23A, which are interposed between the frame 21 and the swing lever 23, respectively.

The control device 19, as shown in FIG.
A discharge is generated between the tip of the torch electrode 25 and the torch electrode 25.

Further, as shown in FIG. 1, the control device 19 drives and controls the aforementioned motor 16 via the motor drive circuit 33, and digitally sets the movement amount of the arm 13 and capillary 14 as described above.

Further, as shown in FIG. 1, the control device 19 drives and controls the aforementioned solenoid 26 via the solenoid drive circuit 34, and controls the set position of the torch electrode 25 with respect to the capillary 14 as shown in (1) and (2) below. do.

(1) That is, the torch electrode 25 is held by the tensile force of the tension spring 27 at a ball forming position set, for example, outside the movement trajectory of the capillary 14. As a result, the control device 19
The tip of the wire 32 and the torch electrode 25 are set at relative positions for forming a ball.

(2) Also, the torch electrode 25 is swung from the ball forming position under the excitation state of the solenoid 26, and the capillary 1
For example, the ball re-forming position is set to the ball re-forming position determined on the movement trajectory of No. 4. As a result, the relative position between the tip of the wire 32 and the torch electrode 25 is reset to a relative position for re-forming the ball, which is closer than the relative position for forming the current ball according to (1) above.

However, in the IIIm device 19, the torch electrode 25 is
1), the electric torch unit 31 is controlled to generate electric discharge between the torch electrode 25 and the tip of the wire 32 to heat the tip of the wire 32, and the tip of the wire 32 is heated. form a ball.

At this time, as shown in FIG.
1. The control device 19 obtains the above-mentioned detection result of the detector 41 every time a ball is formed as described above under the condition that the torch electrode 25 is set at the ball-forming position of (1) above. Then, on the condition that the detector 41 detects an abnormality in the current ball formation, the control device 19 changes the setting of the torch electrode 25 from the ball formation position (1) above to the ball reformation position (2) above. However, the torch unit 31 is further controlled again, and a re-discharge is generated between the torch electrode 25 and the tip of the wire 32 to reheat the tip of the wire 32 and re-form a ball at the tip of the wire 32.

Note that the detector 41 is connected to the torch current f with the capillary 14 in between.
It is placed at a position opposite to the li 25 and detects the outer diameter and eccentricity of the ball. In addition, to detect the outer diameter and eccentricity of the ball diameter, for example, the detection technique described in Japanese Patent Publication No. 61-11464 mentioned above can be used as is.
Detailed explanation will be omitted.

Next, the operation of the bonding apparatus 10 will be explained.

(2) During normal bonding, the control device y119 de-energizes the solenoid 26 and sets the torch electrode 25 to the ball forming position of (1) above, which is outside the movement trajectory of the capillary 14. The control device 19 controls the wire 3 protruding from the capillary 14 by controlling the motor 16.
2 and the torch electrode 25 are set at relative positions for forming a ball.

■The control device 19 controls the electric torch unit 31,
A discharge is generated between the tip of the wire 32 and the torch electrode 25, and a ball is formed at the tip of the wire 32 by this discharge.

(2) The control device 19 obtains the detection results of the detector 41. When this detection result is a ball normal signal, the control device 19:
The xY table 11 and the motor 16 are controlled, and the capillary 14, which moves the wire 32 together with the arm 13, uses the normal ball to connect the part to be joined (IC pellet 5).
1 electrode and the lead of the lead frame 52).

(When the detection result of the al detector 41 is a ball abnormality signal, the control device 19 excites the solenoid 26 and sets the torch electrode 25 on the movement trajectory of the capillary 14.
2) Set the ball to the re-forming position.

(b) The control device 19 re-controls the electric torch unit 31 to re-discharge between the tip of the wire 32 and the torch electrode 25, and this re-discharge re-forms the ball at the tip of the wire 32.

(c) Then, the control device 19 de-energizes the solenoid 26 and changes the setting of the torch electrode 25 to a position outside the movement trajectory of the capillary 14, which is the ball forming position in (1), and also controls the XY table 11 and the motor. control 16;
Using the re-formed ball, the wire 32 is joined to the part to be joined by the capillary 14 which is moved together with the arm 13.

In addition, the control bag "1119 can be used in the above-mentioned (1) on the condition that after the ball is re-formed in (b) above, the detection result of the detector 41 has been obtained and this detection result has been confirmed to be a ball normal signal. (c) may be performed. At this time, if the detection result of the detector 41 is an abnormal signal, the above-mentioned
After repeating the re-discharge and re-forming of the ball in (b), the above
The joining operation (c) can be performed.

Next, the operation of the above embodiment will be explained.

In the above embodiment, during normal bonding work,
The tip of the wire 32 and the electric torch ti25 are set at relative positions for forming a ball, forming a ball, and continuing the bonding work.

On the other hand, due to the bending of the wire 32, variations in length, etc., the ball diameter may be too small or the eccentricity of the ball center line may be too large due to the current ball formation, and this abnormality may be detected by the detector 4.
1 has been detected, the control device 19 controls the wire 3
The relative position between the tip of No. 2 and the wire heating source is made closer than the relative position for forming the ball this time. Then, under this reset state for re-forming the ball, the torch electrode 25 reheats the abnormal ball. During this reheating, the relative position between the tip of the wire 32 and the torch electrode 25 compared to the initial heating is as follows:
Since they are brought close to each other, it is possible to re-form a proper ball with improved ball diameter and eccentricity of the ball center line by reheating. Thereby, highly reliable bonding can be performed.

That is, according to the above embodiment, when the ball formation fails, the It is possible to automatically re-form the ball without stopping the operation of the 1tlO, always obtain a proper ball, and perform highly reliable bonding.

In the above embodiment, the torch electrode 25 is controlled in two positions, the ball forming position and the ball re-forming position. 3, gradually approaching the tip of the wire 32.
It may be possible to control multiple positions.

Furthermore, in implementing the present invention, the abnormal state of the ball detected by the detector is classified into levels, and the amount of change in the relative position between the tip of the wire and the wire heating source is determined according to the degree of the abnormality level classified into the above levels. It may be set analog or digitally.

In addition, in carrying out the present invention, the initial ball formation is performed with the wire heating device disposed on the movement trajectory of the capillary, and on the condition that the detector detects an abnormality in the current ball formation, the tip of the wire is The ball may be re-formed by causing discharge again with the relative positions of the wire heating device and the wire heating device being closer to each other than the current relative position for forming the ball.

Furthermore, in carrying out the present invention, when resetting the relative position for ball formation, either the wire position or the wire heating source position may be set, and both may be set. It's okay.

Further, in carrying out the present invention, the wire heating source is not limited to a torch electrode, but a gas torch or the like can also be used.

[Effects of the Invention] As described above, according to the present invention, when ball formation fails,
It is possible to automatically re-form the ball without stopping the operation of the device, always obtain a proper ball, and perform highly reliable bonding.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a wire bonding apparatus according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the main parts of FIG. 1,
Figure 3 is a schematic diagram showing the capillary drive section in Figure 2;
The figure is a schematic diagram showing the torch drive unit in Figure 2, and Figure 5 is a schematic diagram showing the torch drive unit in Figure 2.
FIG. 6, which is a sectional view taken along the line V-■ in the figure, is a schematic diagram showing a conventional example. DESCRIPTION OF SYMBOLS 10... Bonding device, 14... Capillary, 19... Control device, 25... Torch electrode, 26... Solenoid, 1... Detector.

Claims (1)

[Claims] (1) In a wire bonding apparatus in which the tip of the wire and the heating source of the wire are set at relative positions for forming a ball, the tip of the wire is heated by the wire heating source, and a ball is formed at the tip of the wire. , is equipped with a detector that detects the state of ball formation due to the wire heating source, and on the condition that the detector detects an abnormality in the current ball formation, the relative position between the tip of the wire and the wire heating source is It is characterized by comprising a control device that resets the relative position for re-forming the ball to a position closer to the relative position for re-forming the ball, reheats the tip of the wire by the wire heating source, and attempts to re-form the ball. wire bonding equipment.