JPH10132754A - Device for inspecting appearance of lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspecting device with superior sensitivity in detecting defects which inspects the plating of a lead frame for its appearance defects. SOLUTION: This device comprises a transferring means 140 for samples to transfer samples at a constant speed in one direction, a linear area photographing means 110 to photograph the linear area of a sample surface in a predetermined location orthogonal to the direction of the transfer of samples, a linear illuminating means 130 to illuminate the linear area of the sample surface diagonally at such an angle that the specular reflection light of illumination does not directly enter the linear area photographing means 110. and image processing means 150 to extract the defect part of the sample through the use of the photographed image signal data obtained by photographing the linear area of the sample by the linear area photographing means 110. The image processing means 150 performs comparison processing for comparing the image signal of a sample at every location corresponding to each pixel of the linear area photographing means 110, on the basis of the photographed image signal data obtained by the linear area photographing means 110 with a predetermined set slice level, detects the sections of signals where the level of image signal at every location is out of a predetermined range, and judges the detected sections only within a range set in advance as defect parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting lead frame plating appearance defects using a linear area photographing means. In particular, the present invention relates to an inspection device that can detect plating leakage to a region other than a plating region.

[0002]

2. Description of the Related Art Conventionally, a general method for inspecting a plating appearance defect of a lead frame by performing image processing on image data obtained by photographing a sample includes the intensity of light reflected from a lead frame material surface and a plating surface. There is known a method using an inspection device 800 as shown in FIG. In the method using the inspection apparatus 800 shown in FIG. 8, the surface of the sample 820 is illuminated with illumination light 831 by the illumination means 830, the regular reflection light 835 from the sample surface is captured by the imaging means 810, and the obtained image signal is obtained. Based on the data, the image processing means 850 performs arithmetic processing and the like, and detects a defective portion. In FIG. 8, reference numeral 870 denotes a display unit for displaying a result or the like, and 860 denotes a control unit for controlling the whole. However, according to this method, the difference in intensity between the reflected light from the lead frame material surface and the reflected light from the plated surface is small, and the defect size that can be identified is limited. For this reason, with the increase in density and functionality of semiconductor devices,
This has been a problem because it has not been possible to cope with miniaturization of the inner lead pitch of the lead frame or mass production of the lead frame.

[0003]

As described above, in order to cope with the miniaturization of the lead pitch and the mass production of the lead frame, an inspection apparatus for inspecting the plating appearance defect of the lead frame is shown in FIG. There has been a demand for an inspection apparatus having a higher defect detection sensitivity than 800. The present invention is directed to provide a visual inspection apparatus for inspecting a plating frame for defective appearance of a lead frame, which has excellent defect detection sensitivity.

[0004]

SUMMARY OF THE INVENTION A lead frame appearance inspection apparatus according to the present invention uses a lead frame using image data obtained by photographing a linear region of a sample moving in one direction at a substantially constant speed. Appearance inspection device that detects defective plating of the frame. It is a means for transporting the sample in one direction at a substantially constant speed, and captures a linear area on the sample surface at a predetermined position orthogonal to the direction in which the sample is transported. Linear area photographing means, linearly illuminating means for obliquely illuminating the linear area on the sample surface at an angle such that specular reflected light does not directly enter the linear area photographing means, and linear area photographing means And image processing means for extracting a defective portion of the sample using photographed image signal data obtained by photographing a linear region of the sample by the image processing device. Photo taken Based on the signal data, a comparison process is performed to compare the image signal at each position of the sample corresponding to each pixel of the linear region imaging means with a set predetermined slice level, and the level of the image signal at each position is reduced. It is characterized in that a portion of the signal outside the predetermined range is detected, and only a detected portion within a predetermined region is determined as a defective portion. In the above, the optical axis of the lens system of the linear region photographing means is in a direction substantially orthogonal to the sample surface. When the angle between the optical axis and the sample surface is made variable and the side or edge of the sample is illuminated by the linear illumination means, the reflected light (scattered light) scattered from the side or edge of the sample is a line. The optical axis of the lens system of the linear area photographing means is set to be closer to the illumination light side of the linear illuminating means from a direction perpendicular to the sample surface so that the incident signal level incident on the linear area photographing means does not become larger than the set level. Is characterized by being inclined in the opposite direction. The comparison process is a binarization process for binarizing an image signal at each position of the sample at a predetermined slice level. Further, the image signal for each position in the above is photographed image signal data. Further, the image signal for each position described above is characterized in that it has been subjected to an enhancement process of performing a filter process such as a differential operation process based on the photographed image signal data.

The term "specularly reflected light" means reflected light in which light incident on a sample and light reflected from the sample are opposite to each other at the same angle with respect to a plane perpendicular to the sample surface. Also, image signal data directly obtained by shooting by the linear region shooting means is referred to as shot image signal data, and image data obtained by performing arithmetic processing on the shot image signal data or the shot image signal data is referred to as an image signal. Or image signal data.

[0006]

According to the lead frame appearance inspection apparatus of the present invention configured as described above, it is possible to provide an inspection apparatus for inspecting a lead frame plating appearance defect, which is excellent in defect detection sensitivity. Is what you do. More specifically, a sample transport unit that moves the sample in one direction at a substantially constant speed, a linear region imaging unit that captures a linear region on the sample surface at a predetermined position orthogonal to the sample transport direction, and illumination. Linear illumination means for obliquely illuminating the linear area on the sample surface at an angle such that the specularly reflected light does not directly enter the linear area imaging means, and the linear area of the sample is imaged by the linear area imaging means. And image processing means for extracting a defective portion of the sample using the captured image signal data obtained by the above, wherein the image processing means is based on the captured image signal data obtained by the linear region imaging means. And performing a comparison process of comparing an image signal at each position of the sample corresponding to each pixel of the linear region imaging means with a set predetermined slice level, so that the level of the image signal at each position is out of a predetermined range. Is detected,
This is achieved by judging only a portion within a preset area at the detected location as a defective portion. That is, imaging of the sample by the linear area imaging means
Unlike the conventional inspection method using the apparatus 800 shown in FIG. 8, the linear illumination means is dark field illumination without using regular reflection light, and the defect detection sensitivity is excellent.

More specifically, by setting the optical axis of the lens system of the linear area photographing means in a direction substantially perpendicular to the sample surface, the scattered reflected light (from the side or edge of the lead frame) is obtained. In the case where there is no influence of scattered light, for example, when a lead frame is manufactured by pressing or the like, it is possible to cope with defects of various shapes and to have a high defect detection rate. Further, the angle between the optical axis of the lens system of the linear region imaging means and the sample surface is variable, and when the side surface or the edge of the sample is illuminated by the linear illumination means,
The optical axis of the lens system of the linear area photographing means so that the level of the incident signal at which the reflected light (scattered light) scattered from the side or edge of the sample enters the linear area photographing means does not become larger than the set level. Is tilted from the direction perpendicular to the sample surface to the direction opposite to the illumination light side of the linear illumination means, so that the influence of the reflected light scattered from the side or edge of the lead frame is reduced. In some cases, for example, in the case of a lead frame manufactured by etching or the like and having a tapered side surface, the defect detection sensitivity is increased.

Since the comparison process is a binarization process for binarizing an image signal at each position of the sample at a predetermined slice level, the image signal at each position is converted into a photographed image signal data. Accordingly, the entire image processing, that is, the configuration of the image processing unit is simplified.

Further, since the image signal at each position is subjected to an enhancement process for performing a filter process such as a differential operation process based on the photographed image signal data, the detection sensitivity in the comparison process is increased, It is also possible to detect finer defects.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lead frame appearance inspection apparatus according to the present invention will be described with reference to the drawings. First, the first embodiment
An example is given below. FIG. 1A is a plan view schematically showing a configuration of a first example of an embodiment of a lead frame appearance inspection apparatus according to the present invention, and FIG. 1B is a perspective view of a main part. .
In FIG. 1, reference numeral 100 denotes a lead frame appearance inspection apparatus;
0 is a linear area photographing means, optical axes 111 and 120 are lead frames (samples), 125 is a linear area, 130 is a linear illuminating means, 131 is illuminating light, 135 is specular reflected light, 140 is a conveying means, 150 Is an image processing means, 160 is a control unit, 17
0 is a display unit. The first example uses image signal data obtained by photographing a linear region 125 of a sample (lead frame) 120 moving in one direction at a substantially constant speed by the linear region photographing means 110. And an inspection device for detecting a plating defect of a lead frame for inspecting the appearance of the sample 120. The surface of the sample (lead frame) 120 is dark-field illuminated by the linear illuminating means 130 so that the linear area photographing means 110 Then, based on the obtained image signal data, processing is performed by an image processing means to extract a defective portion. The first example is a case where the signal level of the scattered light on the side surface or the edge of the sample (lead frame) is negligibly smaller than the slice level for detecting a defect in the image processing means 150. Optical axis 111 of the lens system of the lens-shaped area photographing means 110
Is set to an intermediate position between the direction of the illumination light 131 from the linear illumination means 130 and the direction of the specular reflection light 135, that is, a direction orthogonal to the surface of the sample (lead frame) 120, so that defects of various shapes can be dealt with. It is assumed. As described above, the conventional device 80 shown in FIG.
It is assumed that the detection sensitivity is higher than that of the inspection method using 0, and smaller defects can be detected. In addition, this optical axis 1
The angle between 11 and the surface of the sample (lead frame) 120 need not be strictly 90 degrees, but an angle range of ± 15 degrees is preferable in order to cope with defects of various shapes.

In a first example, as shown in FIG. 1, at least a sample transfer means 140 for moving a sample 120 in one direction at a substantially constant speed, and a sample surface at a predetermined position orthogonal to the sample transfer direction. A linear region photographing means 110 for photographing the linear region 125, and a linear shape for illuminating the linear region 125 on the sample surface obliquely at an angle such that specular reflected light does not directly enter the linear region photographing means. Lighting means 130;
An image processing means 150 for extracting a defective portion of the sample by using photographed image signal data obtained by photographing a linear region of the sample by the linear region photographing means. The control unit 160 shown in FIG. 1 is for controlling the operation of each unit in association with each other, and the display unit 170 is for visually checking the inspection result and the like.

Next, extraction of a defective portion by the image processing means 150 will be briefly described below. FIG. 3 is a diagram for explaining the relationship between the inspection area of the sample 120 and the image signal data of each pixel of the linear area imaging means 110, and the like. In the first example, while moving the sample 120 at a substantially constant speed,
The linear region 125 of the sample 120 is captured by the linear region photographing unit 110.
The image signal data of the entire sample 120 is obtained by taking a plurality of images at predetermined time intervals, and, for example, as shown in FIG. An image signal data group corresponding to the entire area is obtained. In FIG. 3, the entire inspection area of the sample 120 is k
The inspection area of the sample 120 is represented by n × k pixels D11 to Dkn.
Note that Dij is a linear area photographing means 1 by the i-th photographing.
It means image signal data of the tenth j-th pixel. Further, the position (X, Y) of each pixel on the sample can be specified by the position of the pixel of the linear region imaging unit 110 and the number of times of imaging. Then, each of the image signal data Dij is compared at a predetermined slice level, and those out of a predetermined range are detected as defect candidates. For example, with respect to each image signal data Dij, one having a signal level higher than a predetermined slice level is binarized to 1 and the other signal levels are binarized to 0, and a portion corresponding to 1 is specified as a defect position candidate. I do.

[0013] Then, the location which is a candidate for the defect position is
Only when the inspection area is in an area that should not be plated, it is determined that the plating is excessively plated due to leakage or the like. For example, FIG.
(A) is a partially enlarged portion of the lead frame in which only the tip of the inner lead 412, a part of the tab suspension lead 411A, and the connecting portion 417 are to be silver-plated. Each of the image signal data corresponding to the inspection region of the obtained sample is binarized, the binarized 1 portion is defined as a white portion, and the 0 portion is defined as a black portion. 4B, since images are usually taken at a resolution lower than the pitch of the inner leads 412, the image is as shown in FIG. FIG. 4 (a) Plating portion 490 due to plating leakage
Is not an area to be plated.
A defect is displayed as 490A in (b). At the same time, the plated portion 490 is automatically determined as a defective portion. That is, the display section 170 shown in FIG. 1 can display such an image, and the presence / absence and position of the defect can be visually confirmed together with the automatic determination of the defect.

When the photographed image signal data is used as it is as the image signal in the image processing, the processing is simple. Further, as an image signal in the image processing, a signal which has been subjected to an enhancement process of performing a filter process such as a differential operation process based on the captured image signal data may be used.
In some cases, the accuracy of detection can be increased.

Next, a second example of the embodiment will be described.
FIG. 2A is a schematic configuration diagram schematically showing the configuration of a second example of the embodiment of the lead frame appearance inspection apparatus of the present invention, and FIG. 2B is a side view of the lead frame. It is the elements on larger scale at the time of lighting. In the second example, as shown in FIG.
2, when the signal level of reflected light (scattered light) from the illumination light is compared with the signal level of the reflected light (scattered light) in the image processing unit of the first example. Fig. 2
As shown in (b), the optical axis 111 of the lens system of the linear area photographing means 110 is directed in a direction in which this effect is not present. The optical axis 111 is illuminated from a direction perpendicular to the surface of the sample 120. It is provided in a direction shifted by an angle θ in a direction other than the light side. The other device configuration, image processing, and the like are the same as those in the first example.

[0016]

The present invention will be described in more detail with reference to examples. FIG. 5 is a schematic configuration diagram of the inspection device of the embodiment. The inspection apparatus of the embodiment is obtained by processing a plurality of lead frames 710 as shown in FIG. 7B into a single unit as shown in FIG. 7A by etching or the like. Is a device for detecting plating failure after silver plating is performed on a wire bonding region or a die pad portion. 5, reference numeral 500 denotes a visual inspection device, 510 denotes a CCD line sensor camera, 520 denotes a lead frame (sample), 520A denotes an uninspected lead frame, 520
B: inspected good lead frame; 520C: inspected defective lead frame; 530: optical fiber guide;
32 is a halogen light source, 534 optical fiber cable, 5
40 is a transport unit, 541 is a roll, 542 is an optical sensor,
Reference numeral 550 denotes an image processing unit (also serving as a control unit), and 570 denotes a monitor. Although not shown in FIG. 5, the inspection apparatus of the embodiment supports the optical fiber guide 530 and adjusts the direction of the illumination light from the optical fiber guide 530, and a CCD line sensor camera. There is a direction adjustment unit that supports the 510 and can adjust the direction of the optical axis of the lens system of the CCD line sensor camera 510.

The appearance inspection apparatus of the embodiment shown in FIG. 5 corresponds to the first example of the embodiment, and a continuous lead frame (sample) 520 is sandwiched at both ends on the short side. While the position is controlled as described above, the transfer unit 540 is moved on the roll 541 at a constant speed in the direction of the arrow. The position of the continuous lead frame (sample) 520 in the transport section 540 is sensed by the optical sensor 542, and based on a command from the optical sensor 542, the CCD line sensor camera 510 moves the sample 520 on the surface of the sample 520. The imaging of the linear region in the direction orthogonal to the direction is performed. Detection of the end of imaging of the continuous lead frame (sample) 520 is also performed by another optical sensor 542A (not shown). The illumination of the linear region of the sample 520 photographed by the CCD line sensor camera 510 is performed by the halogen light source 53.
2 is transmitted by an optical fiber cable 534 and is radiated by a line-type optical fiber guide 530. The specular reflection light is transmitted by a CCD line sensor camera 510.
It is performed with dark-field illumination so as not to enter. FIG. 6 is a diagram showing the direction of the illumination light and the direction of the optical axis of the lens system of the CCD line sensor camera as the photographing means. The optical axis of the lens system of the CCD line sensor camera 510 is a lead frame (sample). From the direction perpendicular to the surface of 520, it is slightly shifted to the side opposite to the illumination light side.

The image signal data captured by the CCD line sensor camera 510 is sequentially sent to the image processing unit 550 to extract a defective portion as described above and display the result on the monitor 570. In the present embodiment, an image processing unit that performs image processing and a control unit that controls each functional unit in association with each other are integrated.

Although not shown here, those inspected and determined to be non-defective are classified into non-defective products while being transported, and those determined to be defective are transported to defective products while being transported. Is classified as In FIG. 5, 520
A, 520B, and 520C are an uninspected lead frame, an inspected good lead frame, and an inspected defective lead frame, respectively.

[0020]

As described above, the present invention makes it possible to provide an appearance inspection apparatus for inspecting a plating appearance defect of a lead frame, which has excellent defect detection sensitivity. As a result, it is possible to cope with the miniaturization of the inner lead pitch of the lead frame and the mass production of the lead frame accompanying the increase in the density and the function of the semiconductor device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first example of an embodiment of the present embodiment.

FIG. 2 is a schematic configuration diagram of a second example of the embodiment of the present embodiment.

FIG. 3 is a diagram for explaining a relationship between an inspection area and image signal data.

FIG. 4 is a diagram for explaining image display of a detection result;

FIG. 5 is a schematic configuration diagram of an embodiment.

FIG. 6 is a diagram showing a direction of illumination light and a direction of an optical axis of a lens system of a CCD line sensor camera.

FIG. 7 is a view for explaining a continuous lead frame;

FIG. 8 is a view showing a conventional lead frame plating appearance inspection apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 appearance inspection apparatus for lead frame 110 linear area photographing means 111 optical axis 120 lead frame (sample) 121 side surface 122 edge 125 linear area 130 linear lighting means 131 illumination light 135 regular reflection light 140 transport means 150 image processing means 160 Control part 170 Display part 411 Die pad 411A Tab suspension lead 412 Inner lead 417 Connection part 480 Plating part 490 Plating adhesion part 490A Defect 500 Visual inspection device 510 CCD line sensor camera 511 Optical axis 520 Lead frame (sample) 520A Untested lead frame 520B Tested good lead frame 520C Tested defective lead frame 520S Sample surface 530 Optical fiber guide 530A Illumination light 530B Reflection light 532 Halogen light source 534 Light Fiber cable 540 Transport unit 541 Roll 542 Optical sensor 550 Image processing unit (also serving as control unit) 570 Monitor 700 Continuous lead frame 701 Frame unit (frame unit) 710 Lead frame 711 Die pad 712 Inner lead 713 Outer lead 714 Dam bar 715 Frame Department

Claims (6)

[Claims] 1. An appearance inspection apparatus for detecting plating failure of a lead frame using image data obtained by photographing a linear region of a sample moving in one direction at a substantially constant speed, comprising: Means for transporting the sample in one direction at a substantially constant speed, a linear area photographing means for photographing a linear area on the surface of the sample at a predetermined position orthogonal to the direction of transport of the sample, Linear illuminating means for obliquely illuminating the linear area on the sample surface at an angle such that it does not directly enter the linear area photographing means; and a photographed image obtained by photographing the linear area of the sample by the linear area photographing means. Image processing means for extracting a defective portion of the sample using the signal data, wherein the image processing means comprises a linear area photographing means based on the photographed image signal data obtained by the linear area photographing means. Corresponding to each pixel A comparison process is performed to compare the image signal of each position of the sample with a set predetermined slice level to detect a signal position where the level of the image signal at each position is outside a predetermined range. An appearance inspection apparatus for a lead frame, wherein only an area within a predetermined area is determined as a defective portion. 2. The lead frame appearance inspection apparatus according to claim 1, wherein the optical axis of the lens system of the linear area photographing means is in a direction substantially orthogonal to the sample surface. 3. The method according to claim 1, wherein the angle formed between the optical axis of the lens system of the linear region photographing means and the sample surface is variable, and the side surface or the edge of the sample is illuminated by the linear illuminating means. The optical axis of the lens system of the linear area photographing means so that the level of the incident signal at which the reflected light (scattered light) scattered from the side or edge of the sample enters the linear area photographing means does not become larger than the set level. Is tilted from a direction orthogonal to the sample surface to a direction opposite to the illumination light side of the linear illumination means. 4. The comparing process according to claim 1, wherein
The image signal at each position of the sample is converted into two at a predetermined slice level.
An appearance inspection device for a lead frame, which is a binarization process for binarizing. 5. The lead frame appearance inspection device according to claim 1, wherein the image signal at each position is photographed image signal data. 6. An image signal at each position according to claim 1, wherein the image signal is subjected to an enhancement process for performing a filter process such as a differential operation process based on the photographed image signal data. Visual inspection device for lead frames.