JPH0752158B2 - Mounted board inspection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting board inspection device for inspecting a mounting failure of soldering on a printed circuit board on which components are mounted.

2. Description of the Related Art Conventionally, the inspection of a solder portion soldered on a printed circuit board has relied on a visual inspection by a human. However, as the products are becoming smaller and lighter, the components on the printed circuit board are becoming smaller and the density is higher. Under such circumstances, human visual inspection has become difficult, and automation of inspection has been strongly desired.

As one of the methods, Japanese Patent Application No. 63-45206 proposes to judge the quality of the solder portion from the cumulative frequency distribution of luminance by using the luminance data with a two-dimensional camera.

FIG. 7 shows the cumulative frequency distribution of non-defective and defective solder when it is attached to the solder portion and illuminated from diagonally above, with the horizontal axis representing the luminance class and the vertical axis representing the cumulative luminance frequency. The non-defective solder portion has many high-luminance portions and thus exhibits a distribution characteristic like the cumulative frequency distribution 701 of the non-defective portion. Since the defective solder portion has many dark portions, the cumulative frequency distribution 702 of the defective portion
Shows distribution characteristics such as. As shown in FIG. 7, the distribution characteristics of the non-defective product and the defective product are different, so that they can be distinguished.

However, in the inspection method shown in the conventional example, the curve of the cumulative frequency distribution differs depending on the displacement of parts, the amount of solder, etc.,
It cannot be judged with sufficient reliability. In addition, there is a problem in that it is difficult to make a difference in the characteristics of pass / fail unless the illumination conditions are optimal. Further, there is a problem that it is necessary to divide an image in a minute area and image it in order to optimize the illumination unevenness depending on the position on the printed circuit board and the illumination conditions.

INDUSTRIAL APPLICABILITY The present invention binarizes a luminance signal with an arbitrary threshold value without depending on the positional deviation of components and the amount of solder, and judges pass / fail by an area ratio of 1 and 0 in a mask set on a land. Therefore, the characteristics of the soldering failure can be more clearly grasped by adding the luminance signals obtained from the two light amount detecting means, and the determination accuracy can be improved.

Means for Solving the Problems In order to achieve the above object, the technical solution of the present invention firstly illuminates a component arranged and soldered on a printed circuit board from a normal direction of the printed circuit board. Illuminating means, two light amount detecting means for detecting scattered light obtained by reflecting from the printed circuit board by illuminating with the illuminating means and outputting a luminance signal, and a luminance signal from the two light amount detecting means. Addition means for adding, binarization means for binarizing the output from the addition means with an arbitrary threshold value, and masking for the position of the soldering land provided on the printed circuit board. An area ratio of 1s and 0s in the mask is calculated by a mask storage unit that stores mask data of an arbitrary size, a binarized signal from the binarization unit, and mask data from the mask storage unit. However, a judgment processing means for judging the quality of soldering from the area ratio is provided.

Secondly, an illuminating means for illuminating the component arranged and soldered on the printed board from the normal direction of the printed board,
Two light amount detecting means for detecting scattered light obtained by reflecting from the printed circuit board by illuminating with the illuminating means and outputting a luminance signal, and a luminance signal from the two light amount detecting means at arbitrary threshold values. Two binarized each
A binarizing means for outputting a value signal, a synthesizing means for synthesizing the two binary signals, and a predetermined arbitrary size for masking the position of the soldering land provided on the printed circuit board. An area ratio of 1s and 0s in the mask is calculated by a mask storage unit that stores mask data, a signal from the synthesizing unit, and mask data from the mask storage unit, and whether the soldering is good or bad is determined from the area ratio. And a determination processing means.

Thirdly, in the first and second means, the illuminating means has a laser light source and a laser scanning means for scanning the laser light from the laser light source on the printed board by the polygon mirror and the fθ lens. The light amount detecting means is provided at a position symmetrical to the scanning surface of the laser light.

With the above-described structure, the present invention takes an image of the printed circuit board illuminated from the normal direction of the printed circuit board from the same normal direction, binarizes the luminance signal from the imaging means, and uses the binarized signal in the mask. The area ratio of 1 and 0 is calculated, and whether the soldering is good or bad is determined based on the area ratio. Two light amount detecting means are provided at positions symmetrical to the scanning plane of the laser light and obtained from the respective light amount detecting means. The characteristics of the soldering failure can be more clearly understood by obtaining the binarized signal by integrating the luminance signals by the synthesizing means or the adding means.

Example Hereinafter, the operation principle of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram showing the operating principle of the mounting board inspection apparatus of the present invention. In FIG. 1, 101 is a printed board, 102 is a component mounted on the printed board 101, 103 is an illuminating means for illuminating the printed board 101, and 104 is an imaging means such as a CCD camera for picking up the image of the printed board 101. Reference numeral 106 is a binarizing means for binarizing the luminance signal 105 from the image pickup means 104, and 107 is a mask storage means for storing in advance a mask for mask processing. Reference numeral 108 denotes a judgment processing means for judging the quality of soldering, and the respective constituent elements are as follows. 109 is a total counter that calculates the total area in the mask, 110
Is a 0 counter that calculates the area of 0 in the mask in the binarized signal, 111 is a divider that calculates the area ratio of 1 and 0 in the mask, and 112 is a threshold value for determining the quality of soldering. Threshold storage means for storing, 113 is a comparator for comparing the result of the divider 111 and the threshold from the threshold storage means 112, and 114 is a binarized signal.

The operation will be described below.

The printed circuit board 101 on which the component 102 is mounted is illuminated from the normal direction of the printed circuit board 101 by an illumination means 103 such as a ring illumination, and the printed circuit board 1 is also imaged by an imaging means such as a CCD camera.
An image is taken from the normal direction of 01 to obtain a luminance signal 105. The binarization means 106 compares the luminance signal 105 with an arbitrary threshold value and outputs a binarized signal 114. In the judgment processing means 108, the printed circuit board
Mask data of a predetermined size for masking the position of the land for soldering provided on 101 is input from the mask storage means 107, and the mask data and the binary value from the binarization means 106 are input. The conversion signal 114 is used to calculate the area ratio of 1s and 0s in the mask, and the quality of soldering is determined from the area ratio. That is, the mask storage means 107
According to the mask data from, all counter 109 counts all the binary signals in the mask, and 0 counter 110
In the case of the binary signal in the mask, only the signal of 0 is counted. In the divider 111, the output of all counters 109 and 0
The ratio of the output of the counter 110 is calculated, and the comparator 113 compares the area ratio value from the divider 111 and the value from the threshold value storage means 112 storing the quality judgment threshold value of the solder portion, and soldering is performed. The quality of a part is determined.

Regarding the method of judging the quality of this soldered portion, FIG. 2 and FIG.
A more detailed description will be given with reference to the drawings.

2 (a) and 2 (b) show elements on the side surface and the flat surface of the printed circuit board 201 to which the component 202 is soldered. The irradiation light 203 (, ...) Irradiated on the printed circuit board 201 by a light certifying means such as a ring certifying member is a component 202.
The reflected light 204 from the upper surface or the solder surface is condensed on the optical transmission conversion element of the CCD camera installed in the normal direction of the printed circuit board 201 (upper direction in the figure) and converted into a luminance signal.

In particular, the solder part 205 and the electrode part 206 are characterized by forming a mirror surface and being specularly reflected. In FIG. 2 (a), irradiation light 203
(,, ...) are on the land 207 and the electrode portion 206, respectively.
The reflected light 204 (′, ′, ... ′) is irradiated onto the solder fillet 205 and above, and is reflected. At this time, in the flat electrode portion 206 and a part of the land 207, ′ and ′ of the reflected light 204 are reflected to the photoelectric conversion element side and converted into a high brightness signal as a brightness level. The irradiation light 203 irradiated onto the non-planar solder fillet 205 has a characteristic that it is specularly reflected by the solder fillet 205 and does not return to the photoelectric conversion element side as'of the reflected light 204. Looking at this as a luminance signal, as shown in FIG. 2B, the flat electrode portion 206 and a part of the land 207 become a bright bright portion 208, and the angled portion such as the solder fillet 205 becomes dark. Dark part 209
Becomes

With respect to the characteristics of the luminance signal around the soldered portion under such epi-illumination, a mask A210 (shown by a broken line) as shown in FIG. 2B is set on the land 207 in an arbitrary size. In this mask A210, 1 (bright portion 209) and 0 (dark portion 21) of the binarized signal generated by binarizing the luminance signal at an arbitrary luminance level are generated.
0) is compared to determine the quality of the soldered portion.

For example, as shown in FIG. 3, when determining the quality of the soldered portion based on the area ratio of the binary signal 0 (dark portion) to the entire mask, it is determined whether the dark portion area ratio is larger or smaller than the threshold value A301. Can be separated. That is, in the case of no solder (a) 302 and the solder shortage (b) 303, the area ratio of the dark portion in the mask becomes small because the solder fillet is less formed. In addition, when determining the case of excessive solder (d) 305 in which the area ratio of the dark part becomes too large compared to the good product (c) 304,
By providing the threshold value B306, it can be distinguished from a non-defective product.

As described above, in the present embodiment, the luminance signals of the lighting unit, the image pickup unit, the mask and the soldering unit that accurately capture the characteristics of the light reflection of the soldering unit are binarized, and the area ratio of the luminance signals of the soldering unit is used. By the binarization and determination processing means for determining pass / fail, it is not necessary to set delicate illumination conditions, and a mask is set on the land to be soldered, and the relative area of the binarized signal in the mask is set. Since the ratios are compared, it does not depend on the amount of solder, shape, size of parts, etc.
Very reliable decisions can be made.

Next, the basic configuration of the present invention will be described with reference to FIG.

FIG. 4 is a block diagram showing the basic configuration of the mounting board inspection apparatus of the present invention. In the basic configuration, instead of the illumination means and the imaging means for obtaining the luminance signal in the first embodiment, another means using laser light is used, and a luminance signal similar to the operating principle can be obtained. .

In FIG. 4, 401 is a printed circuit board, 402 is a component mounted on the printed circuit board 401, and 403 is a printed circuit board 401.
404 is an arrow indicating the moving direction of the carrying means for moving. As a laser beam scanning means, 405 is a laser light source, 4
Reference numeral 06 is a laser beam from the laser light source 405, 407 is a polygon mirror, 408 is a mirror for guiding the laser beam 406 to the polygon mirror 407, and 409 is an fθ lens. Further, as a light amount detecting means, 410 is a condenser lens and 411 is a light detecting element. In addition,
105 is a luminance signal from the photodetector 411, 106 is a binarization unit, 107 is a mask storage unit, 108 is a determination processing unit,
Since these are the same as the operation principle of the present invention, the same reference numerals are given and detailed description will be omitted.

The operation will be described below.

The printed circuit board 401 on which the component 402 is mounted is used as the transfer means 40.
While moving in the direction of arrow 404 by 3, laser light source 405
Using the three mirrors 408 for the laser source 406 from, the polygon mirror 407 is guided to the rotating polygon mirror 407.
And the laser light 406 by the fθ lens 409 to the printed board 401
Irradiate vertically on top. As a result, the laser light 406 is two-dimensionally scanned over the printed circuit board 401.

Scattered light reflected from the printed board 401 by scanning with the laser light 406 is condensed on the photodetection element 411 which is a photoelectric conversion element through the fθ lens 409 and the polygon mirror 407, and further through the condenser lens 410, The brightness signal 105 is output.

Since the operation after this is the same as the operation principle, it will be briefly described. However, the luminance signal 105 is binarized by the binarizing means 106, and the binarized signal and the mask data from the mask storage means 107 are used. The determination processing means 108 has 1 and 0 in the mask.
Area ratio is calculated, and the quality of soldering is determined from the area ratio.

As described above, in the basic configuration, the laser beam and the polygon mirror,
By using the fθ lens, the condenser lens and the photodetector, it is possible to obtain a similar luminance signal of the printed circuit board by means different from the first operation principle, and by irradiating the laser beam perpendicularly to the printed circuit board. It is possible to eliminate the adverse effect of uneven illumination due to the position on the printed circuit board. Also, by selecting the number of revolutions of the polygon mirror, the spot diameter of the laser beam, and the moving speed of the conveying means, it is possible to increase the resolution of the luminance signal on the printed circuit board much more easily than when using a CCD camera or the like. Therefore, the soldered portion can be inspected with higher accuracy.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 5 is a block diagram showing an embodiment of the mounting board inspection apparatus of the present invention. In FIG. 5, a condenser lens 501 and a light detecting element 502, which are light quantity detecting means, are provided one by one at positions symmetrical to the scanning plane of the laser light, and an adding means 504 is used to detect the light from these two light detecting elements. 4 except that the luminance signals (105 and 503) are added and output to the binarizing means 106, the configuration is the same as that of FIG. 4 shown in the basic configuration of the mounting board inspection apparatus of the present invention. The same reference numerals are given and their explanations are omitted.

The operation will be described below.

Printed circuit board 4 with component 402 mounted, similar to the basic configuration
The laser beam 406 is guided to the polygon mirror 407 and is vertically irradiated onto the printed circuit board 401 through the fθ lens 409 while moving 01 by the transporting means 403.

The scattered light reflected from the printed board 401 by the scanning of the laser beam 406 is provided, via the fθ lens 409 and the polygon mirror 407, to the condenser lenses 410 and 501 and the photodetector which are provided at positions symmetrical to the scanning plane of the laser beam. It leads to 411,502. Then, the luminance signals 105 and 503 are output from the photodetecting elements 411 and 502, the both luminance signals are added by the adding means 504, and then binarized by the binarizing means 106. Using the binarized signal and the mask data from the mask storage means 107, the determination processing means 1
At 08, the area ratio of 1 and 0 in the mask is calculated, and the quality of soldering is judged from the area ratio.

Among the above operations, the operation of providing two light amount detecting means and adding the two obtained brightness signals will be described with reference to FIG.

FIG. 6 shows a state of solder failure caused by a positional deviation of components soldered on a printed circuit board. 60
1 is a printed circuit board, 602 is a component soldered to the printed circuit board 601, 603 is an electrode part of the component 602, 604 is a land, 6
Reference numeral 05 is a defective soldering portion, 606 is laser irradiation light, and 607 is reflected light. In the defective soldering state as shown in FIG. 6 (a), the irradiation light 606 and the reflected light 607 are ′ and ′, respectively.
As reflected in different directions. Looking at this as a luminance signal, as shown in FIG. 6B, in the luminance signal from one photodetector, the bright portion is the bright portion A608 and the bright portion B609, and the dark portion is the dark portion 611. On the other hand, in the luminance signal from the other photodetector, the bright portion is the bright portion A608 and the bright portion C (inside the broken line portion) 610, and the dark portion is the dark portion 611. That is, in the case of a solder defect as shown in FIG. 6 (a), the area of the bright portion, which appears as a characteristic of the defect, can be grasped larger by providing two photodetecting means and adding both luminance signals. You can do it.

As described above, in the present embodiment, the characteristics of the soldering defect are further clarified by providing the light detecting means at a position symmetrical to the scanning surface of the laser light and adding the luminance signals from both the light detecting means by the adding means. Therefore, the accuracy of determining the quality of the soldered portion can be improved.

In this embodiment, the luminance signals from both light detecting means are added by the adding means and then binarized by the binarizing means. However, both luminance signals are first binarized by the binarizing means, and then both of them are binarized. Even if the binarized signal is combined by a combining means such as a logical OR circuit, the same effect as in the present embodiment can be obtained, and the order of combining the binarized signal and both luminance signals does not limit the present invention. Not something to do.

As described above, as an effect of the present invention, the luminance signal is binarized by an arbitrary threshold value, and the area ratio of 1 and 0 in the mask is calculated by the binarized signal and the mask data.
By determining the quality of soldering from the area ratio, the amount of solder can also be determined without being affected by the positional deviation, and the two light amount detecting means are placed at positions symmetrical to the scanning plane of the laser light. By providing the two brightness signals obtained from both light amount detecting means and adding them together, the characteristics of the solder failure can be more clearly grasped and the judgment accuracy can be improved, so that a great effect of automating the inspection and improving work efficiency. Can be obtained.

[Brief description of drawings]

FIG. 1 is a block connection diagram of a mounting board inspecting apparatus according to the first operation principle of the present invention, FIG. 2 is an explanatory view of a soldering part quality judgment method by the apparatus, and FIG. FIG. 4 is a block connection diagram of the mounting board inspection apparatus in the basic configuration example of the present invention, FIG.
FIG. 5 is a block connection diagram of a mounting board inspection apparatus according to an embodiment of the present invention, FIG. 6 is a state diagram of a solder defect caused by misalignment, and FIG. 7 is a cumulative frequency distribution of a conventional soldering portion inspection. FIG. 101 ... Printed circuit board, 102 ... Parts, 103 ... Illumination means, 104 ... Imaging means, 106 ... Binarization means, 107 ... Mask storage means, 108 ... Judgment processing means, 405 ... Laser light source , 407 …… Polygon mirror, 409 …… fθ lens, 410
...... Condensing lens, 411 …… Photodetector.

Front page continuation (72) Inventor Yufumi Tsuda 3-10-1, Higashisanda, Tama-ku, Kawasaki, Kanagawa Matsushita Giken Co., Ltd. (72) Hiromon Toba 4-3, Tsunashima-east, Kohoku-ku, Yokohama No. 1 in Matsushita Communication Industrial Co., Ltd. (56) Reference JP-A 64-13442 (JP, A) JP-A 59-69728 (JP, A)

Claims (3)

[Claims] 1. A lighting unit for illuminating a component arranged and soldered on a printed circuit board from a direction normal to the printed circuit board, and scattered light obtained by being reflected by the printed circuit board by being illuminated by the lighting system. Of the two light amount detecting means for detecting the luminance signal and outputting the luminance signal, an adding means for adding the luminance signals from the two light amount detecting means, and a binary value for binarizing the output from the adding means with an arbitrary threshold value. Conversion means, mask storage means for storing mask data of a predetermined arbitrary size for performing mask processing on the position of the land for soldering provided on the printed circuit board, and binarization from the binarization means. A mounting board comprising a judgment processing means for calculating the area ratio of 1 and 0 in the mask based on the signal and the mask data from the mask storage means, and judging the quality of soldering from the area ratio.査 apparatus. 2. Illumination means for illuminating a component arranged and soldered on a printed board from a direction normal to the printed board, and scattered light obtained by illuminating with the illumination means and reflected from the printed board. And two light amount detecting means for detecting the luminance signal and outputting a luminance signal, and a binarizing means for binarizing the luminance signals from the two light amount detecting means respectively with arbitrary threshold values and outputting two binary signals. A synthesizing means for synthesizing the two binary signals; a mask storing means for storing mask data of a predetermined arbitrary size for masking at a position of a soldering land provided on the printed circuit board; Judgment processing means for calculating the area ratio of 1 and 0 in the mask based on the signal from the synthesizing means and the mask data from the mask storage means, and judging whether the soldering is good or bad from the area ratio. Comprising a mounting board inspection apparatus. 3. The illuminating means includes a laser light source, and laser scanning means for scanning the laser light from the laser light source on a printed circuit board by a polygon mirror and an fθ lens. The mounting board inspection apparatus according to claim 1, wherein the mounting board inspection apparatus is provided at a position symmetrical with respect to the scanning surface.