JPH1183754A - Lead frame inspection equipment - Google Patents

Abstract

(57) [Problem] To provide a lead frame inspection device capable of improving the inspection speed while maintaining the inspection accuracy. A one-dimensional sensor is scanned while a lead frame to be inspected is moved by a motor, and the result is output to a control unit.
The position of each diver (5) is previously stored in the control unit (22) as the distance (a, b, c, d) from the end surface of the lead frame, and the control unit (22) moves the lead frame. The distance is compared with the distances (a, b, c, d), and if the moved distance matches the distances (a, b, c, d), the motor drive unit (23) is controlled. To change the rotation speed of the motor (24). As a result, the lead frame moves at a low speed while the one-dimensional sensor (21) scans the inner lead forming region of the lead frame, and moves at a high speed while scanning the other regions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame inspection apparatus, and more particularly, to improving an inspection speed while preventing a decrease in inspection accuracy by changing an imaging resolution in accordance with an area of a lead frame to be inspected. The present invention relates to a lead frame inspection device that can be operated.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a lead frame used for mounting a chip and performing resin molding is generally made of a thin metal plate. In particular, a change in shape such as bending or warping is likely to occur.

[0003] Such a shape change causes chip bonding failure or the like and hinders the manufacture of a semiconductor device. Therefore, conventionally, the shape inspection is performed by an optical method or a method visually inspected by an inspector. .

[0004] Of the above-mentioned inspection methods, the visual inspection method is inefficient in terms of inspection accuracy and inspection speed.
Conventionally, an optical inspection method of imaging the appearance of a lead frame using an imaging device such as a one-dimensional sensor or a two-dimensional sensor and inspecting the shape of the lead frame by pattern matching or feature extraction by a microcomputer is generally used. in use.

In the above-described imaging, the imaging device is scanned at a constant interval while moving the lead frame at a constant speed.
A process of capturing the entire surface of the lead frame as an image is performed.

[0006]

However, in the above-described conventional optical inspection method, if the resolution of imaging is increased to increase the inspection accuracy, the inspection speed is correspondingly reduced. On the other hand, if the inspection speed is increased, the imaging resolution is necessarily lowered, and it has been difficult to improve the inspection accuracy and / or inspection speed without deteriorating one or both of them.

Accordingly, an object of the present invention is to provide a lead frame inspection apparatus capable of improving the inspection speed while maintaining the inspection accuracy.

[0008]

In order to achieve the above object, according to the present invention, an image pickup means for picking up an image of a lead frame and an inspection means for checking the lead frame based on an output of the image pickup means are provided. In the lead frame inspection apparatus provided, a moving unit for moving an imaging position of the imaging unit on the lead frame, a detection unit for detecting an imaging position of the imaging unit, and a detection unit corresponding to the imaging position detected by the detection unit And a resolution control means for changing the resolution of the imaging means at a desired position on the lead frame to a high resolution.

According to a second aspect of the present invention, in the first aspect of the present invention, the resolution control means includes a speed control means for controlling a moving speed of the moving means.

According to a third aspect of the present invention, in the first aspect of the invention, the resolution control means includes an imaging interval control means for controlling an imaging interval of the imaging means.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the inspection means processes the image of the lead frame imaged at a high resolution by the imaging means. Means, comparing means for comparing the image of the lead frame processed by the image processing means with an image of a normal lead frame, and determining means for determining a defect of the lead frame based on a comparison result by the comparing means And characterized in that:

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the lead frame inspection apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

First, an outline of the present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram showing a schematic configuration of a lead frame inspection device according to the present invention. FIG. 1 shows the structure of a lead frame inspection apparatus according to the present invention, the structure of a lead frame to be inspected, and the relationship between these components.

A lead frame inspection apparatus according to the present invention comprises:
As shown in FIG. 1, the one-dimensional sensor 21 performs scanning while moving the lead frame to be inspected by the motor 24, and outputs the result to the control unit 22. Control unit 2
2, the position of each diver 5 is stored in advance as the distance (a, b, c, d) from the end surface of the lead frame, and the control unit 22 determines the distance that the lead frame has moved and the distance (a, b). , C, d), and if the moved distance matches the distance (a, b, c, d), the motor driving unit 23 is controlled to change the rotation speed of the motor 24. As a result, the lead frame is
1 moves at a low speed while scanning the inner lead forming area of the lead frame, and moves at a high speed while scanning the other areas.

The structure of the lead frame shown in FIG. 1 will be further described. The lead frame includes a die pad 1 which is a flat portion for bonding a semiconductor chip, a suspension pin 2 for holding the die pad, and a surface electrode of the semiconductor chip. Inner leads 3 that are directly connected to the device, and outer leads 4 that are connected to electrodes on the package or printed circuit board.
A diver 5 formed at the boundary between the inner lead and the outer lead to hold each lead; a jig hole 6 for inserting a guide pin of a mold for positioning the lead frame in the mold; It is composed of a slit 7 serving as a boundary when dividing the frame, and a frame outer frame 8 serving as an outer frame of the lead frame.

Here, the lead frame to be inspected by the lead frame inspection apparatus according to the present invention has a lead width,
Since the shape change of the inner lead, which is minute in both pitch and pitch, is most likely to occur, at the time of inspection, the area of the lead frame on which the inner lead 3 is formed (hereinafter, referred to as “inner lead formation area”) is particularly focused. preferable.

Therefore, in the present invention, as shown in FIG.
In order to adjust the inspection accuracy based on the diver 5 formed at the boundary between the inner lead 3 and the outer lead 4, the position of each diver 5 is stored as a distance (a, b, c, d) from the end surface of the lead frame. Keep it.

For the distances (a, b, c, d), design dimensions defined at the time of pattern design may be used.
The position of the diver of the actually manufactured lead frame may be measured, and the result may be used. Although only four distances a, b, c, and d are shown in FIG. 1, the values to be stored increase according to the number of divers 5.

The value to be stored is not limited to the position of the diver 5, but can be changed as appropriate depending on the location to be inspected. For example, since the shape of the tip of the inner lead is more likely to change, the position of the tip may be stored.

In the lead frame inspection device according to the present invention, as the adjustment of the inspection accuracy, a means for changing the resolution of the image pickup by the one-dimensional sensor 21 is used, and the inspection device corresponds to the stored position of the diver 5. To switch the imaging resolution. By switching the imaging resolution,
The lead frame to be inspected has a low-resolution imaging area 10
Thus, a high-resolution imaging region 11 is formed.

The structure of the lead frame inspection device that operates as described above will be further described. The inspection device includes a one-dimensional sensor 21 in which photoelectric conversion elements are arranged in an array, and a resolution switching device that stores a position at which the imaging resolution is switched. A position storage unit 20, a motor 24 for transporting the lead frame,
A motor drive unit 23 that drives a motor 24 and a control unit 22 that controls the above-described functional units and performs pattern inspection of a lead frame are configured.

Here, the one-dimensional sensor 21 is installed on the upper surface of the lead frame, and is arranged at a position where the entire pattern formed on the lead frame can be imaged.

As described above, the distances (a, b, c, d) shown in FIG. 1 are stored in the resolution switching position storage section 20 in advance.

Hereinafter, the configuration of the control unit 22 will be described in more detail. FIG. 2 is a block diagram showing a functional configuration of the control unit shown in FIG. As shown in the figure, the control unit 22 includes a sensor driving circuit 51 that outputs a scanning instruction to the one-dimensional sensor 21 at predetermined intervals, and an A / D converter that converts a scanning signal from the one-dimensional sensor 21 into a digital signal. Vessel 52 and A / D
An image memory 53 for storing a digital signal output from the converter 52, a pattern memory 54 for storing a normal lead frame shape pattern as a digital signal, and a digital signal stored in the image memory 53 and stored in the pattern memory 54. An AND operation unit 55 that performs an AND operation with the digital signal obtained from the control unit 22, a microcomputer 50 serving as a function center of the control unit 22, and a monitor 56 that displays an inspection result and the like.

Next, the control unit 22 configured as described above
Will be described.

When the control unit 22 moves the lead frame to be inspected, the microcomputer 50 outputs a control signal to the motor driving unit 23 to drive the motor 24 at a predetermined rotation speed. As a result, the rotation speed of the rotated motor 24 is fed back to the microcomputer 50.

The microcomputer calculates the rotation speed of the motor 24 from the fed-back rotation speed, and controls the motor drive unit 23 to increase the rotation speed of the motor 24 when the rotation speed has not reached the predetermined rotation speed.

When the control unit 22 causes the one-dimensional sensor 21 to perform scanning, the microcomputer 50 outputs a control signal to the sensor drive circuit 51, and the sensor drive circuit 51 receiving the signal outputs the control signal to the primary at predetermined intervals. The original sensor 21 performs scanning.

Next, the operation for taking in an image signal will be described with reference to FIG.

FIG. 3 is a flowchart showing an execution procedure of an image signal fetching process executed by the control unit shown in FIG. When the lead frame inspection apparatus according to the present invention captures an image of a lead frame, first, the microcomputer 50 outputs a control signal to the motor driving unit 23 to drive the motor 24 as described above, and Move at the speed of

Next, the microcomputer 50 converts the number of rotations fed back from the motor 24 into a moving distance of the lead frame, and executes integration of the moving distance (step 100).

Then, the result of the integration is compared with the position of the diver stored in the resolution switching position storage section 20 (step 101). Control is performed to change the rotation speed of the motor 24 (step 102). Here, the motor drive unit 23 can control the motor 24 at two types of rotation speeds, low speed and high speed. In step 102, if the motor 24 is rotating at low speed,
If the motor is rotating at a high speed, the speed is switched to a low speed.

The speed at which the lead frame is moved is controlled so that the inner lead forming area is not scanned at the start of the inspection, so that the lead frame moves at a low speed. If you move to the next diver's position, it will switch to low speed. As a result, when the one-dimensional sensor 21 scans the inner lead formation region, the one-dimensional sensor 21 operates at a low speed, and when scanning the other regions, the one-dimensional sensor 21 operates at a high speed.
If the integration result does not coincide with the resolution switching position in step 101, the process proceeds to step 103 without switching the motor speed.

Next, the microcomputer 50 controls the sensor drive circuit 51 while moving the lead frame at the speed set as described above to control the one-dimensional sensor 21.
Perform scanning (step 103).

The one-dimensional sensor 21 outputs the scanning result, that is, an electric signal corresponding to the shape of the scanning portion of the lead frame to the A / D converter 52. The A / D converter 52 converts this electric signal into a digital signal (step 10).
4) Output to the image memory 53.

Digital signals are stored in the image memory 53 in the order of input (step 105).

The microcomputer 50 can form an image using the data stored in the image memory as described above, and this image is as shown in FIG.

FIG. 4 is a diagram showing an image when an image is formed from the data accumulated by the image signal capturing process shown in FIG. As shown in the figure, the image is an image corresponding to the actual lead frame in the inner lead forming area, but the other area is an image compressed in the horizontal direction. That is, a high-resolution part 13 and a low-resolution part 12 are formed in the image.

The lead frame inspection apparatus according to the present invention performs a shape inspection by pattern matching the image shown in FIG. 4 with the image of a normal lead frame.

In this pattern matching, only the high resolution section 13 is compared, and the low resolution section 12 is not compared.

In this case, the center of the high resolution section 13 is determined from the actual dimensions of the lead frame, and the center of the high resolution section 13 is compared with a normal lead frame. Here, the center is determined, for example, as follows.

First, the microcomputer 50 is configured as shown in FIG.
Are obtained from the image shown in FIG. Next, the dimensions from the side surface to the center of the actual die pad, which are obtained in advance, are converted into pixel values, and the pixel values are added to the coordinates. The coordinates obtained as a result are set as the center coordinates of the high resolution unit 13.

The pattern matching as described above is executed for all the high resolution units 13.

Next, an example of pattern matching different from the above will be described with reference to FIG.

FIG. 5 is a diagram showing an image when only the inner lead forming area is fetched by the image signal fetching process shown in FIG. 3 to form an image.

The image shown in the figure is obtained by scanning only the inner lead forming area and not scanning the other areas. Such a scanning control is performed by stopping the one-dimensional sensor when the lead frame moves at high speed. For example, the method of performing the scanning and the scanning result at the time of high-speed movement may not be stored in the image memory, and may be executed by any means.

Since the image obtained in this way is composed only of the high-resolution section 13, the pattern matching can be executed in the order in which the data is stored, without finding the center of the image as described above.

In the inspection of the shape of the lead frame, in addition to the above-described pattern matching, data stored in the image memory may be compared bit by bit.

FIG. 6 is a flowchart showing an execution procedure of the pattern inspection processing executed by the control unit shown in FIG.
In the pattern inspection process shown in FIG. 3, an image stored in an image memory is processed in frame units (for example, a pattern for one semiconductor device), and pattern matching is performed.

In this pattern inspection process, as shown in FIG. 2, the data stored in the image memory 53 and the data stored in the pattern memory 54 are output to an AND calculator 55, and the calculation result is output to the microcomputer 50. Is to be processed.

Here, the pattern memory 54 stores image data corresponding to a normal shape of the lead frame. The accumulation of the normal-shaped image data is performed by scanning a lead frame inspection apparatus according to the present invention in which a normal-shaped lead frame is formed, and performing A / D conversion in the image signal capturing process shown in FIG. This is performed by storing the output of the converter 52 in the pattern memory 54.

The frame period for executing the AND operation is performed by counting the read signals output to the image memory 53 and the pattern memory 54 by the macro computer.

Hereinafter, an execution procedure of the pattern inspection process shown in FIG. 6 will be described.

First, the microcomputer 50 determines whether or not the processing of one frame is completed by counting a predetermined frame period (step 20).
0). Naturally, the process has just started at first, so the result in step 200 is No.

Next, the microcomputer 50 outputs a read signal to the image memory 53 and the pattern memory 54, and outputs the data stored in each memory to the AND calculator 55 (Step 201).

Here, the AND operator 55 determines whether or not the data output from the pattern memory 54 is "1" before executing the AND operation (step 20).
2) If not "1", the AND operation is not performed and the process returns to step 200.

If the data output from the pattern memory 54 is "1", an AND operation is executed (step 203), and it is determined whether the result is "1" (step 204). When the result of the AND operation is "1", it means that the data output from the image memory 53 and the data output from the pattern memory 54 are the same.

If the result of the operation is "1" in step 204, the flow returns to step 200 to determine whether or not the processing of one frame has been completed, and repeats the above processing until the processing of one frame has been completed.

If the operation result is not "1" in step 204, the microcomputer 50 outputs an error to the monitor 56 (step 205), and displays a message indicating that there is an abnormality in the shape of the lead frame under inspection. .

As described above, according to the present invention, the movement of the lead frame at the time of imaging is performed at a low speed in the inner lead forming region and at a high speed in the other regions. The imaging resolution is increased, and the other parts are reduced in imaging resolution, so that desired inspection accuracy and inspection speed can be obtained as a whole.

In the above-described embodiment, the inspection accuracy and the inspection speed are improved by controlling the moving speed of the lead frame to be inspected.
Instead of controlling the moving speed, the scanning timing of the one-dimensional sensor may be controlled.

In this case, the microcomputer 50
Controls the sensor drive circuit 51 and detects the position of the diver so that the scanning interval of the one-dimensional sensor 21 is switched, that is, in step 102 shown in FIG.
The switching of the scanning interval is executed instead of the motor rotation speed switching.

As a result, the scanning interval is short in the inner lead forming area, and the scanning interval is long in the other areas. As a result, the imaging resolution in the inner lead forming area is increased.

As described above, by controlling the interval for scanning the lead frame to be shorter in the inner lead forming area and longer in the other areas, the amount of data stored in the image memory is reduced. Time can be shortened.

In the above embodiment, the imaging is sequentially performed by moving the lead frame to be inspected. However, the one-dimensional sensor 21 may be moved instead.

[0066]

As described above, according to the present invention,
By moving the lead frame during imaging at a low speed in the inner lead formation area and at a high speed in other areas, the imaging resolution of the inner lead, which is likely to cause shape defects, is increased, and the other parts are imaging resolution. And the desired inspection accuracy and inspection speed can be obtained as a whole.

By controlling the interval for scanning the lead frame to be short in the inner lead forming area and long in other areas, the data stored in the image memory is reduced. The time can be shortened.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a schematic configuration of a lead frame inspection device according to the present invention.

FIG. 2 is a block diagram showing a functional configuration of a control unit shown in FIG. 1;

FIG. 3 is a flowchart showing an execution procedure of an image signal capturing process executed by a control unit shown in FIG. 1;

FIG. 4 is a diagram illustrating an image when an image is formed from data accumulated by the image signal capturing process illustrated in FIG. 3;

FIG. 5 is a diagram showing an image when only an inner lead formation area is fetched and an image is formed by the image signal fetching process shown in FIG. 3;

FIG. 6 is a flowchart showing an execution procedure of a pattern inspection process executed by the control unit shown in FIG. 1;

[Explanation of symbols]

1 ... die pad, 2 ... hanging pin, 3 ... inner lead,
4 ... Outer lead, 5 ... Diver, 6 ... Jig hole, 7 ...
Slit, 8: frame outer frame, 10: low-resolution imaging area, 11: high-resolution imaging area, 12: low-resolution section, 13
... High resolution part, 20 ... Resolution switching position storage part, 21 ... One-dimensional sensor, 22 ... Control part, 23 ... Motor drive part, 24
... Motor, 50 ... Microcomputer, 51 ... Sensor drive circuit, 52 ... A / D converter, 53 ... Image memory, 5
4. Pattern memory, 55 AND operator, 56 monitor.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Zenichi Ishikawa 2-10-1 Komine, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Mitsui High-Tech Co., Ltd.

Claims (4)

[Claims] An imaging means for imaging a lead frame;
A lead frame inspection apparatus comprising: an inspection unit that inspects the lead frame based on an output of the imaging unit; a moving unit that moves an imaging position of the imaging unit on the lead frame; Detection means for detecting, and resolution control means for changing the resolution of the imaging means at a desired position on the lead frame to a high resolution in accordance with the imaging position detected by the detection means. Lead frame inspection equipment. 2. The lead frame inspection apparatus according to claim 1, wherein said resolution control means includes a speed control means for controlling a moving speed of said moving means. 3. The lead frame inspection apparatus according to claim 1, wherein the resolution control unit includes an imaging interval control unit that controls an imaging interval of the imaging unit. 4. An image processing means for processing an image of the lead frame imaged at a high resolution by the imaging means, an image of the lead frame processed by the image processing means, 4. The lead frame according to claim 1, further comprising: comparing means for comparing the image of the lead frame with the image of the lead frame; and determining means for determining a defect of the lead frame based on a result of the comparison by the comparing means. Inspection equipment.