JP2001007147A - Method and device for detecting adjustment of frame press, and wire bonding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To get a certain adjustment result in a short time concerning the quantity of floating of frame press. SOLUTION: This device is equipped with the first memory 34 which stores the level position of a tool at the time of the tool 10 contacting with a lead and stopping there by applying the first load weaker than the spring force of the lead in condition that the lead is clamped, the second memory 35 which stores the level position of the tool at the time of the tool 10 contacting with the lead and stopping there by applying the second load weaker than the spring force of the lead, and an operating part 32 which computes the quantity 36 of the floating of the lead by operating the difference between the level positions of the tool stored in the first and second memories 34 and 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting adjustment of frame holding and a wire bonding apparatus.

[0002]

2. Description of the Related Art In a wire bonding step in an assembling step of a semiconductor device, there is a step of clamping a lead of a lead frame placed on an upper surface of a heat block or a heat block fixed to the heat block by a frame holder. In addition, as this kind of wire bonding equipment,
For example, JP-A-4-262545, Japanese Patent No. 2817
No. 080 and the like.

With the recent miniaturization of semiconductor devices, high precision is required for processing lead frames. In order to cope with such a lead frame, the frame holder and the heat block or the heat block are processed with a precision of the order of μm in accordance with the shape of the lead frame. Therefore, it is necessary to assemble the frame retainer with respect to the heat block or the heat block with high accuracy in the wire bonding apparatus. For this purpose, the leads of the lead frame must be uniformly pressed all around. If the assembly adjustment of the frame retainer is insufficient, a state in which a part of the lead is lifted by the spring force of the lead at the time of clamping occurs. If wire bonding is performed in this state, the bonding force for bonding the wire to the lead becomes insufficient,
Connection failure occurs.

[0004]

The mounting adjustment of the frame retainer is performed by, after assembling the frame retainer, positioning and mounting the lead frame on a horizontally adjusted heat block or heat block, and connecting the lead of the lead frame with the frame retainer. It is pressed against the heat block or heat block and clamped to adjust the flatness of the frame holder. In the adjustment of the flatness, the worker presses the lead with tweezers or the like and visually confirms that the lead does not float. Therefore, the adjustment operation has to rely on the intuition and experience of the worker. Further, even if it is found that the flatness (clamp) is insufficient, it is not possible to quantitatively grasp the details of adjustment (inclination direction, height difference, etc.), and the adjustment is performed by trial and error. Also, the results of assembly adjustment differed for each worker, and quantitative observation was not possible in quality control.

SUMMARY OF THE INVENTION An object of the present invention is to provide a frame holding adjustment detecting method and apparatus and a wire bonding apparatus capable of obtaining a fixed adjustment result in a short time.

[0006]

According to the present invention, there is provided a wire bonding apparatus for clamping a lead of a lead frame mounted on an upper surface of a frame mounting table with the frame holder. Applying a first load weaker than the spring force of the lead to the tool while the lead is clamped to memorize the tool height position when the tool comes into contact with the lead and stops; and Applying a strong second load to the tool to store the tool height position when the tool comes into contact with the lead and stops, and calculating the difference between the two stored tool height positions to lift the lead. Detecting the amount.

In order to solve the above-mentioned problems, a frame holding adjustment detecting device according to the present invention is characterized in that a lead of a lead frame mounted on an upper surface of a frame mounting table is clamped by a frame holding device. In this state, a first load that is weaker than the spring force of the lead is applied to the tool to store the tool height position when the tool comes into contact with the lead and stops, and a second load that is stronger than the spring force of the lead. Is applied to the tool to calculate the difference between the tool height position stored in the first memory and the second memory that stores the tool height position when the tool comes into contact with the lead and stops when the tool stops. And a calculation unit for calculating the amount of lift of the lead.

According to another aspect of the present invention, there is provided a wire bonding apparatus including the frame holding adjustment detecting device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a heat block 3 is provided between guide rails 2 for guiding a lead frame 1. Above the heat block 3 in the bonding station, a frame retainer 4 for pressing the lead frame 1 against the heat block 3 is provided.
Are arranged. The frame retainer 4 is provided with a vertical movement block 5 which is vertically driven by a vertical driving means (not shown).
It is fixed at. The heat block 3 is also driven up and down by vertical drive means (not shown).

A bonding arm 11 having a tool 10 at one end is disposed above the heat block 3, and the bonding arm 11 is fixed to one end of a support frame 12. The support frame 12 is attached to a moving table 14 via a leaf spring 13 assembled in a cross shape so as to be vertically swingable.
It is mounted on the Y table 15. A coil 17 of a linear motor 16 is fixed to the other end of the support frame 12,
The magnet 18 of the linear motor 16 is fixed to the moving table 14. At the rear end of the support frame 12, a linear scale 19 is fixed.
9, a position sensor 2 of a position detector 22 including a position sensor 20 and an encoder 21
0 is fixed.

Accordingly, the support frame 12 and the bonding arm 11 swing about the leaf spring 13 by the driving of the linear motor 16, and the tool 10 moves up and down.
The moving table 1 is driven by driving the XY table 15.
4. The support frame 12, the bonding arm 11, and the tool 10 move in the XY directions. By combining the vertical movement of the tool 10 and the movement in the XY directions, a wire (not shown) inserted into the tool 10 is connected between a pad of a semiconductor pellet (not shown) fixed to the lead frame 1 and a lead of the lead frame 1. Here, the ball formed at the tip of the wire is bonded to the pad which is the first bond point, and the other end of the wire is bonded to the lead which is the second bond point. When bonding a ball to the first bond point and a wire to the second bond point,
A bonding load is applied from the linear motor 16 to press and connect the ball or wire to the first and second bond points by the tool 10.

The linear motor 16 is controlled by a computer 30. The computer 30 has a control unit 31, a calculation unit 32, and a memory unit 33. A current is applied to the linear motor 16 from the control unit 31 and the tool 10
Is generated, that is, a load is generated. FIG. 2 shows the tool height at the time of detecting the floating of the lead of the lead frame 1. The first load applied when the tool reaches the search level 52 is a load weaker than the spring force of the lead 1a shown in FIG. 3, and the second load 41 applied thereafter is the lead 1a.
The load is set to be stronger than the spring force.

The output of the encoder 21 is input to the control unit 31, and the actual height position of the tool 10 is obtained by the calculation unit 32. That is, since the ratio of the vertical movement amount of the tool 10 to the vertical movement amount of the linear scale 19 is given to the calculation unit 32 in advance, the output value of the encoder 21 is calculated based on the ratio. By performing the calculation at 32, the actual height position of the tool 10 is obtained.

The memory unit 33 includes two memories 34 and 35
Having. The memory 34 stores the height position of the tool 10 when the first load 40 is applied, and the memory 35 stores the height position of the tool 10 when the second load is applied. The difference between the height positions of the tool 10 stored in the memories 34 and 35, that is, the lead floating amount 36 is calculated by the calculation unit 32 and displayed on the monitor 37 in a graph, for example.
In the memory unit 33 and the monitor 37, A, B, C, D
Indicates the position of the lead to be detected. The inclination direction of the frame retainer 4 can be determined by measuring the floating amounts of the leads at the four corners. A, B, C, and D indicate the positions of the leads at the four corners.

Next, the operation will be described. 2A shows a normal state (when there is no floating), FIG. 2B shows a case where the lead 1a has floating, and FIG.
1) to (a3) show normal cases, and (b1) to (b3) show cases where the lead 1a is floating. When the lead frame 1 is clamped by the frame holder 4, the position of the lead 1a of the lead frame 1 for detection by a camera (not shown) is detected. The position of the lead 1a for detection is calculated by calculating an image detected by the camera and information previously taught to the computer 30, and the XY table 15 is driven to position the tool 10 above the lead 1a. . In this state, the tool 10 is lowered and raised as shown in FIG.

In FIG. 2, the tool 10 is lowered 51 at a higher speed than the origin 50 position. When the tool 10 reaches the search level 52, the load of the linear motor 16 is changed to the first load 4
0, and the speed of the tool 10 is reduced to a low speed 53. 3 (a1) and (b1) show a state in which the tool 10 is at the search level 52. The first load 40
Is set to a value that does not depress the lead 1a, for example, 10 g or less. This small first load 40 causes the tool 10
Descends until it contacts the lead 1a. The current height position of the tool 10 at which the descent stops due to the contact of the tool 10 with the lead 1 a is determined by reading the linear scale 19 by the position sensor 20, the encoder 3
4 is stored.

When the lead 1a is not lifted as shown in FIG. 3 (a1), the tool 10 is used as shown in FIG. 3 (a2) and FIG.
As shown in (a), it descends to the original position of the surface of the lead 1a. However, if the lead 1a floats from the heat block 3 due to the spring force as shown in FIG.
1) and as shown in FIG. 2 (b), it comes into contact with the floating lead 1a and stops.

Next, the second necessary for pushing down the lead 1a
A load 41, for example, 100 g, is generated on the linear motor 16. After the application of the second load 41, the height position of the tool 10 is stored in the memory 35 through the encoder 21 and the control unit 31 by reading the linear scale 19 by the position sensor 20. When the lead 1a has no lift, even if the second load 41 is applied, FIG. 3A3 is the same as FIG. 3A2, and the values stored in the memory 34 and the memory 35 are the same. . However, when the lead 1a is floating, when the second load 41 is applied, the tool 10 descends 54 until the lead 1a contacts the heat block 3 as shown in FIG. 3 (b2) from FIG. 3 (b2). . That is, the memory 34 and the memory 3
There is a difference between the values stored in 5. Therefore, the calculation unit 32 obtains the difference between the height positions of the tool 10 stored in the memory 34 and the memory 35. If this difference, that is, the lead floating amount 36 is within the allowable range, there is no floating in the lead 1a, indicating that there is no problem.

After the application of the second load 41 to detect whether or not the lead lifting amount 36 of the lead 1a is within the allowable range, the tool 10 is raised 55 to the origin 50. This gives 1
The detection of the lead floating amount 36 for one lead 1a ends. By the way, the inclination direction of the frame retainer 4 can be determined by measuring the leads 1a at the four corners. this is,
This can be achieved by detecting the leads 1a at the four corner positions A, B, C, and D by the above-described method. The memory unit 33 shows an example of the detection results of the leads 1a at the four corner positions A, B, C, and D. The lead floating amount 36 is 0 at the A position, 5 at the B position, 9 at the C position, and 5 at the D position. The result is displayed on the monitor 37 in a bar graph or the like that is easily visually determined. From the monitor 37, the frame holder 4 is moved from the C position to the A position.
It can be seen that it is inclined downward in the direction of the position. Based on this result, the inclination of the frame holder 4 is adjusted.

In the above embodiment, the case where a heat block or a heat block is used as the frame mounting table has been described, but it goes without saying that a frame mounting table without a heater may be used. Also, the first load 40
To detect the height position of the tool 10, and then apply the second load 41 to detect the height position of the tool 10.
Conversely, the height position of the tool 10 may be detected by applying the second load 41, and then the height position of the tool 10 may be detected by applying the first load 40.

[0021]

According to the present invention, there is provided a step of applying a first load weaker than the spring force of a lead in a state where the lead is clamped and storing a tool height position when the tool comes into contact with the lead and stops. Applying a second load stronger than the spring force of the lead to store the tool height position when the tool comes into contact with the lead and stops, and calculating the difference between the two stored tool height positions. And the step of detecting the floating amount of the tool, a constant adjustment result can be obtained in a short time.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a wire bonding apparatus of the present invention.

FIGS. 2A and 2B show the height of a tool, wherein FIG. 2A is a relationship diagram in a normal state, and FIG. 2B is a relationship diagram in a case where a lead floats.

3A and 3B show a lowered state of a tool when a load is changed, wherein FIG. 3A is an explanatory diagram in a normal state, and FIG. 3B is an explanatory diagram in a case where a lead floats.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 1a Lead 3 Heater block 4 Frame holder 10 Tool 11 Bonding arm 16 Linear motor 19 Linear scale 20 Position sensor 30 Computer 31 Control unit 32 Operation unit 33 Memory unit 34, 35 Memory 36 Lead floating amount

Claims (3)

[Claims] In a wire bonding apparatus for clamping a lead of a lead frame mounted on an upper surface of a frame mounting table with a frame press, a first load weaker than a spring force of the lead is applied to a tool while the lead is clamped. A step of storing the tool height position when the tool comes into contact with the lead and stops when the tool comes into contact with the lead; and a step of applying a second load stronger than the spring force of the lead to the tool and stopping the tool when the tool comes into contact with the lead and stops. A method for detecting a frame holding adjustment, comprising: a step of storing a tool height position; and a step of calculating a difference between the two stored tool height positions to detect a floating amount of a lead. 2. A wire bonding apparatus for clamping a lead of a lead frame mounted on an upper surface of a frame mounting table with a frame press, wherein a first load weaker than a spring force of the lead is applied to the tool while the lead is clamped. A first memory for storing the tool height position when the tool comes into contact with the lead and stops when the tool comes into contact with the lead, and a second load stronger than the spring force of the lead is applied to the tool and the tool comes into contact with the lead and stops. A second memory for storing the tool height position at the time, and a calculation unit for calculating the difference between the tool height positions stored in the first memory and the second memory to calculate the floating amount of the lead. A frame holding adjustment detecting device characterized by the above-mentioned. 3. A wire bonding apparatus comprising the frame holding adjustment detecting device according to claim 2.