JPH09236487A - Method for inspecting cover tape of embossed tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily inspect the cover tape of an embossed tape in a short time by eliminating the difficulty of setting the threshold value of judging the quality or a problem point such as noise. SOLUTION: The method for inspecting the cover tape of an embossed tape comprises the steps of disposing a light source 5 sidewise or obliquely above of the flat surface of the cover tape 2 so as to reflect the emitting light of the source 5 by the tape 2 without emitting the light to a surface mounting component sealed in the embossed tape and to strengthen the contrast of the brightness on the uneven part of the flat surface of the tape 2, capturing the image of the embossed tape by a camera 4 disposed oppositely to the flat surface of the cover tape, forming the histogram of the lightness, deciding the threshold value from the distribution, forming the processed image converted to different one gradation on the region of the histogram divided by the threshold value, and examining whether there exists the pixel of the different gradation near the constituting part of the image or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the sealing state, scratches, tears, etc. of a cover tape after housing surface-mounted components in an embossed tape.

[0002]

2. Description of the Related Art Surface mounting is used as a means for mounting discrete components and ICs on a single substrate.
This is the work of inserting the lead terminals of each component into the conventional through holes and then soldering the electrical connection between each lead terminal and the board pattern on the back side of the component mounting surface of the board, solder printing, mounting of surface mount components. Instead of reflowing, the process is automated and high-density mounting is aimed at.

Among the series of surface mounting operations, there is mounting of surface mounting components. This is for mounting surface mounting type semiconductor devices such as SOP and chip capacitors which are continuously housed in embossed tape by a mounter device. This is a process in which surface-mounted components such as chip components are sequentially taken out and continuously mounted at predetermined positions on the substrate surface.

As shown in FIG. 7, the embossed tape 1 comprises a carrier tape 3 having an embossed 3a formed thereon and a semitransparent cover tape 2 which covers the opening of the embossed 3a.
Both are made of plastic. A surface mount component (not shown) is enclosed in a cavity surrounded by the emboss 3a and the cover tape 2. The cover tape 2 is attached (sealed) to the embossed opening side of the carrier tape 3 by thermocompression bonding. Depending on the sealing condition, surface mounting parts may become dirty or the mounter device may malfunction, so inspection after sealing is indispensable.

Conventionally, in the cover tape inspection method for embossed tape, light from a ring type illumination 9 is applied from above as shown in FIG. In each case, the brightness is recorded at about 64 to 256 gradations, then the embossed tape is pitch-fed, the images are sequentially captured by the camera 4, and the image signal is sent to the image processing device 7, and the same floor obtained thereby is obtained. The image to be inspected composed of pixels of the lightness of the tone was superposed and compared, and the state of the seal and the breakage of the cover tape 2 were judged based on the difference.

[0006]

In the inspection method as described above, there is some variation in the characteristic that the sealing is performed by thermocompression bonding, and it is difficult to set the threshold value for the determination, and in addition, the pixel having the multi-gradation brightness is selected. The processing became complicated and time-consuming. Also, since the cover tape is translucent,
The image of the surface-mounted component stored below it becomes noise in determining the scratches and tears of the cover tape itself, and it is difficult to determine pass / fail. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to easily and quickly perform a cover tape inspection of an embossed tape.

[0007]

In order to achieve the above object, the present invention provides a step of irradiating a sealed embossed tape with light from a light source, a step of sequentially capturing images of the embossed tape with a camera, and a step of using the camera. The recognized image is recorded in the image processing device for each pixel with multi-level brightness, a histogram of brightness and the number of pixels is created, and the threshold value for dividing the brightness corresponding to each component from the distribution of the histogram is determined. Forming a processed image in which each constituent part of the image is converted into lightness of one different gradation in each of the regions separated by the threshold value of the histogram so as to be represented by the lightness of one gradation excluding a defective portion, A cover tape inspection of an embossed tape, which comprises a step of checking, in each constituent part of the processed image, whether or not there is a pixel having a gradation brightness different from a gradation brightness corresponding to the constituent part. In the method, the light source does not illuminate the surface-mounted components enclosed in the embossed tape, the light of the light source is reflected by the cover tape, and the contrast of light and dark in the unevenness on the plane of the cover tape is enhanced. The camera is arranged laterally or obliquely above the plane of the cover tape, and the camera is arranged to face the plane of the cover tape.

Further, the seal width is checked by counting the number of pixels having the lightness of gradation corresponding to the seal portion of the cover tape in the processed image in the width direction of the seal portion of the cover tape, and the seal width is determined by the size of the seal width. It is characterized by making a pass / fail judgment.

With this structure, of the light incident on the camera, the light from the surface-mounted components enclosed in the embossed tape is significantly reduced. In addition, since the contrast of light and darkness in the defective portion, that is, the uneven portion such as scratches and tears of the cover tape is emphasized, by capturing this image with the camera facing the plane of the cover tape, only the unevenness portion has the brightness of the gradation in the vicinity It is recorded with a gradation of lightness with a marked separation.

Further, the seal portion of the cover tape can be clearly distinguished from other image constituent portions (for example, the unsealed portion of the cover tape), and each constituent portion has the same level of gradation lightness except for the defective portion. Therefore, the size of the seal portion can be clarified. Further, the seal width can be measured by counting the number of pixels, and the quality of the seal width can be determined by the magnitude of the measured value.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals may be used in a plurality of drawings, but these indicate the same or corresponding ones.

FIG. 1 is a diagram showing an embodiment of the present invention, in which 5 is a line type illumination and 6 is a tape guide. In the embodiment shown in this figure, the sealed embossed tape is set on the tape guide 6, and two line type illuminations 5 are arranged on both sides of the tape guide 6, and the light is projected on the plane of the cover tape 2 of the embossed tape. Irradiated uniformly. The image of the cover tape 2 and its vicinity is converted into an image signal by the camera 4, and the image signal is sent to the image processing device 7 and subjected to image processing. The image signal is processed by this image processing so that the defective portion can be easily identified.

An embossed tape carrier tape,
The cover tape and the tape guide are made to have different light reflectances by changing the surface condition such as surface roughness and changing the material and the color. If this is not done, it may not be possible to determine where each part extends from. Further, in this way, a plurality of peaks corresponding to each part can be made to appear separately on the histogram, and the threshold value described later can be easily determined. For example, the tape guide 6 is made of metal and has a relatively rough surface so that light is diffusely reflected, the cover tape 2 is a semitransparent plastic film, and the carrier tape 3 is a black plastic molded product. Further, although the seal portion of the cover tape is a part of the cover tape, it is adhered to the carrier tape 3 by thermocompression bonding,
The light reflectance is different. As a result, the brightest part is the background tape guide 6, then the unsealed part of the cover tape 2, the sealed part, and the carrier tape 3 in this order.
Each of the mountains appearing on the histogram shown in (a) corresponds to each part.

Image processing is performed as follows. First, apply the sealed embossed tape to the device in Figure 1,
The image is captured by the camera 4 and the image signal is sent to the image processing device 7. The image signal is analyzed by the image processing device 7 to obtain a histogram as shown in FIG. This figure shows the histogram of an ideal sealed embossed tape, where the horizontal axis is the brightness and the vertical axis is the number of pixels. The camera 4 is a CCD camera having a resolution of 300 × 250 pixels, and the RAM of the image processing device is 8 bits. In other words, the brightness can be recorded with 256 gradations per pixel, in other words, the minimum unit that constitutes an image can take any of 256 levels of brightness. As shown in the figure, four peaks appear in the histogram. As described above, the light reflectance of the parts that make up the embossed tape and the tape guide are different, so the peak at the position with the highest gradation of lightness. Is the background tape guide 6, and the next highest mountain is the unsealed portion 2a of the cover tape 2, followed by the sealed portion 2.
b, the carrier tape 3 in this order. If there are many noise components and it is difficult to obtain peaks, the image is filtered. After the above work, the value of the lightness of the portion where the number of pixels in the drawing is the smallest as compared with the number of pixels in the vicinity thereof is determined as a threshold value, and divided into areas indicated by A, B, C, and D. Therefore, A corresponds to the carrier tape 3, B corresponds to the sealed portion 2b, C corresponds to the unsealed portion 2b, and D corresponds to the tape guide 6.

In the image processing apparatus 7, for the areas thus divided, all the pixels having the lightness existing in the area A, for example, are 20, and B, C, and D are 70, 200, and 25, respectively.
Convert to 0 and combine into 4 gradations of brightness (4 values)
Then, the histogram becomes as shown in FIG. Along with this, the image shows the tape guide 6 and the unsealed portion 2 as shown in FIG.
a, the seal portion 2b, and the carrier tape 3 each have a constant gradation of lightness to form a patterned processed image,
The image is displayed on a monitor (not shown) connected to the image processing device 7. However, since the ideal embossed tape is used in FIG. 3, there is no defect. If there is a defect, the image will be as shown in FIG. 4, which will be described later. In other words, by converting the pixels in the area delimited by the threshold value on the histogram (FIG. 2A) into one different gradation lightness (FIG. 2B), the image structure corresponding to that area is formed. The part is represented by the brightness of one gradation except for the defective part (FIGS. 3 and 4). It should be noted that this quaternarization can be easily realized by a simple circuit using a comparator or arithmetic processing by a microcomputer or the like. Further, the setting of the threshold value is automatically executed by a program set in advance in the image processing apparatus 7, and the quaternarization, the image storage, the pattern matching between the images, and the quality judgment are also automatically executed.

A problem when performing image processing (data compression) such as the above-mentioned four-valued conversion is that there is always a noise component in the image pickup system and it may be difficult to determine whether it is a defective portion or noise. That is, even a defective portion has the same brightness as that of a normal portion. In the embodiment of the present invention shown in FIG. 1, since the light sources are on both sides of the embossed tape,
When there is a defect in the embossed tape, in the case of a convex defect, the light from the light source hits the convex portion and is reflected to the camera side to increase the brightness. Further, when there is a concave defect, the light from the light source does not reach the concave portion, so that the brightness decreases. In this way, the contrast of lightness and darkness is emphasized, and the lightness of the defective portion changes significantly. Therefore, when there is a defective portion, the pixel corresponding to the defective portion is subjected to image processing such as quaternarization, and the brightness of the gradation corresponding to each constituent portion of the processed image (the level of the pixel in the area divided by the threshold is The lightness of the tones is converted into the lightness of one gradation, and the lightness of the converted gradation is included as the lightness of a different gradation. For example, the pixel of the portion corresponding to the unsealed portion 2a of the cover tape falls into the area C on the histogram of FIG. 2A, but if there is a tear, the pixel of that portion surely falls into the area A, and is processed. On that image, only that part is clearly displayed as the brightness of the gradation different from that of the neighborhood.

FIG. 4 shows an example of a processed image when the image of the sealed embossed tape when there is a defect is quaternized. In this figure, 2c is a tear portion of the cover tape, 2d is a peeled portion of the cover tape, Reference numeral 2e denotes an incompletely sealed portion of the cover tape, and 2f denotes a seal shift portion of the cover tape in which a part of the carrier tape 3 is exposed at a portion to be sealed. As shown in the figure, the tear portion 2c does not reflect the light from the light source, and therefore has the same gradation as the carrier tape 3 having the lowest brightness, and the peeling portion 2d and the incomplete seal portion 2e are in close contact with the carrier tape. Since there is no lightness, the lightness is the same as that of the unsealed portion 2a, and the unsealed portion 2f has the same lightness as the carrier tape 3 because the underlying carrier tape 3 is exposed. Therefore, if the processed image shown in FIG. 3 is used as a standard and the processed image of the sealed embossed tape having a defect shown in FIG. 4 is overlaid and compared by the pattern matching method, the defective portion is detected and it is determined as a defective product. To be done.

Further, the presence or absence of a defect can be determined by judging whether or not there is a pixel having a lightness of a tone different from that of a tone corresponding to each part, and therefore an inspection can be performed without performing pattern matching with a standard image. It is also possible to do so. For example, when inspecting for defects in the seal portion of the cover tape, a pitch of several pixels is set in the longitudinal direction of the seal portion, and the seal portion is set in the width direction of the seal portion at each pitch in the seal portion set at the time of the above four-value quantization The number of pixels having the brightness of the corresponding gradation is counted. By doing so, it is possible to measure the width of the seal portion, and it is possible to determine whether the measured width is good or not depending on whether or not the experimentally obtained predetermined range indicating a good product is satisfied. Similarly, the quality of other parts can be determined from the measured value.

As described above, the embodiment in which the quality judgment is performed based on the measured value is very effective for the quality judgment of the seal portion. This is because the seal width has only to satisfy the minimum required width, and variations due to non-uniformity of thermocompression bonding in a range exceeding this are not related to the quality of the product. In other words, it is possible to make a pass / fail judgment in accordance with the actual situation, as compared with the pattern matching method in which the standard image is absolutely used.

FIG. 5 shows an embodiment using a line type illumination 5 and a total reflection mirror 8 instead of the pair of light sources, and FIG. 6 shows an embodiment using a ring type illumination 9. In both cases, the contrast of light and dark is emphasized in the defect portion, so that
The effect similar to that of the embodiment shown in FIG.

Although the embodiment has been described above, the present invention is not limited to this, and various modifications can be made. For example, the line-type and ring-type light sources were used in the above-described embodiments, but the light source is not limited to this and may be any light source that emits light from both sides of the embossed tape or from the surroundings. However,
The surface mount device enclosed in the embossed tape is positioned laterally or obliquely above the plane of the cover tape so as not to be directly irradiated with light. Ideally, the light source irradiates toward the center of the cover tape from a position which is about 50 mm above the center of the cover tape and about 10 mm above the plane of the cover tape. It should be noted that a cover or the like should be provided so that the irradiation light of the light source is not directly irradiated to the camera side, or a light source having a gentle directivity should be used.
In the above embodiment, the RA built in the image processing apparatus is used.
Although M is set to 8 bits, the number is not limited to this and may be any number as long as a clear threshold value can be obtained and the efficiency of image processing is not reduced.
However, if four-valued data is to be formed as in the above-described embodiment, four peaks must be formed on the histogram, so the number of bits is inevitably 2 bits or more, but the noise width of the imaging system must be taken into consideration. It is important that the number of bits is sufficient.

[0022]

As described above, the defective portion, that is, the uneven portion such as scratches or tears of the cover tape, is emphasized in the contrast of light and dark by the light source arranged laterally or obliquely above the plane of the cover tape. By capturing this image with a camera facing the plane of the cover tape, only the uneven portion is recorded with the lightness having a distinct gap from the lightness in the vicinity, so that a clear threshold value not influenced by noise can be set. In addition, the light from the light source does not directly reach the surface-mounted components inside the emboss, and most of the light that is incident on the camera is scattered light generated on the cover tape surface. There is no perceived image of surface-mounted components, and noise due to the presence of surface-mounted components is significantly reduced.

Further, as described above, since the brightness of the defective portion has a value different from that of the vicinity, the defect is checked by checking whether or not each portion has a value different from the brightness corresponding to the portion. You can see if Furthermore, the threshold value is obtained from the histogram by the image processing device, the multi-level lightness is converted to several levels of lightness by this, and when a processed image is created, the seal part of the cover tape has the same level except for the defective part. Since the brightness becomes gradation, the seal width can be easily measured, and the size and continuity of the width itself can be determined in a short time instead of the relative inspection by comparison with the standard image.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing histograms of a captured image and a processed image.

FIG. 3 is a diagram showing an example of an ideal processed image of a sealed embossed tape.

FIG. 4 is a diagram showing an example of a processed image of a sealed embossed tape having a defect.

FIG. 5 is a diagram showing an embodiment in which a line type illumination and a mirror are used.

FIG. 6 is a diagram showing an embodiment when a ring type illumination is used.

FIG. 7 is a perspective view showing an outline of an embossed tape.

FIG. 8 is a configuration diagram of a conventional embossed tape inspection device.

[Explanation of symbols]

 1 Embossed tape 2 Cover tape 2a Unsealed part 2b Sealed part 3 Carrier tape 3a Embossed 4 Camera 5 Line type illumination 6 Tape guide 7 Image processing device 8 Total reflection mirror 9 Ring type illumination

Claims (2)

[Claims] 1. A step of irradiating a light from a light source to a sealed embossed tape, a step of sequentially capturing images of the embossed tape with a camera, and an image recognized by the camera, each pixel being multi-layered by an image processing device. The brightness is recorded as a gradation, a histogram of the brightness and the number of pixels is created, and a threshold for dividing the brightness corresponding to each constituent part is determined from the distribution of the histogram, and each constituent part of the image is one floor except for the defective part. A processed image is formed by converting the areas delimited by the threshold value of the histogram into one different gradation of lightness as represented by the lightness of the gradation, and forming a processed image in each constituent part of the processed image corresponding to the constituent part. A method of inspecting a cover tape for an embossed tape, the method comprising: checking for the presence of a pixel having a brightness different from that of the gradation, wherein the light source is enclosed in the embossed tape. The surface mounted components that are exposed to light are
The light of the light source is reflected by the cover tape, and the contrast of light and dark in the unevenness on the plane of the cover tape is enhanced,
A cover tape inspection method for an embossed tape, wherein the camera is arranged laterally or obliquely above the plane of the cover tape, and the camera is arranged opposite to the plane of the cover tape. 2. The seal width is checked by counting the number of pixels of the brightness of gradation corresponding to the seal portion of the cover tape in the processed image in the width direction of the seal portion of the cover tape,
The cover tape inspection method for an embossed tape according to claim 1, wherein the quality of the seal width is determined based on the size of the seal width.