JPH07117383B2 - Electronic component mounting inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an electronic component mounting inspection method.

(Prior Art) After mounting electronic components such as resistors and capacitors (mounting electronic components) on a printed circuit board, the following means have been proposed for inspecting the mounting state. That is, an image obtained by alternately irradiating oblique rays from two directions on a printed circuit board on which electronic components such as a capacitor are mounted is captured by a photoelectric conversion unit, for example, a television camera, and converted into an electric signal to be converted into an image by a computer. A means for detecting the position and shape of the mounted electronic component by processing has been developed (JP-A-55-155205).

According to the mounting detection means, the mounting state of the electronic component can be easily inspected and detected, but it is difficult to say that the mounting state is sufficiently satisfactory in terms of accuracy and reliability. That is, when a mounting inspection is performed on a printed circuit board on which a large number of electronic components are mounted, it takes a long time to inspect because the image obtained by alternately irradiating the oblique rays may be unclear. Also, there was a problem in terms of reliability.

(Problems to be Solved by the Invention) Therefore, the present invention provides an electronic component capable of highly reliable detection or inspection of an error in the mounting position of an electronic component mounted or an abnormality in the component shape by simple image processing. The purpose is to provide a mounting inspection method.

[Structure of Invention]

(Means for Solving Problems) The present invention provides a step of mounting a printed circuit board on which a ridgeline or a busbar of a mounted electronic component is arranged in a certain direction on a support base, and By irradiating the electronic component from directions opposite to each other through photoelectric conversion means for capturing an image of the electronic component from above, which is inclined with respect to the direction of the ridgeline or the generatrix, and by irradiating light from the light source. A step of capturing an image of the electronic component from above and converting it into an electric signal by the photoelectric conversion means; and a step of image-processing an output signal output by the photoelectric conversion means by an image processing device. This is an electronic component mounting inspection method.

(Operation) With the above configuration, the image or image displayed on the printed circuit board outputs a constant output signal by the light emitted from at least two directions. That is, since the mounted electronic components are always irradiated with light from the oblique direction with respect to the ridgeline or the generatrix thereof, all the electronic components show a predetermined image or image. Therefore, the output from the photoelectric conversion means is also uniform for all the mounted electronic components, so that the reliability of the inspection of the mounted components is improved. It is also possible to detect whether or not the electronic component has an abnormal shape by comparing the output with an electric signal (image processing) while moving a reference image of the electronic component stored in advance.

(Example) The present invention will be described below with reference to FIGS. 1 and 2 showing an example of the present invention. In FIG. 1, (1) is a support base,
(2) is a printed circuit board on which an electronic component (2a), which is an object to be inspected, is mounted, and is placed on the support base (1).
Therefore, the printed circuit board (2) includes electronic components (2a) such as resistors, capacitors, and semiconductor elements, for example, ridge lines or bus bars of the respective electronic components (2a) and the substrate (2).
It is arranged and mounted so that the side of b) is parallel or orthogonal to the side. Further, (3) and (4) are light sources, for example, lamps that alternately irradiate the printed circuit board (2) with light from different directions.
For (4), the one having substantially the same irradiation intensity on the surface to be irradiated of the printed circuit board (2) is selected. (5) is a photoelectric conversion means, for example, a television camera, which picks up an image when the printed circuit board (2) is alternately irradiated with the light sources (3) and (4) from the vertically upper side thereof and converts it into an electric signal. Further, (6) is a means for image-processing the output signal output from the photoelectric conversion means (5), and is configured as follows. That is, a signal output from the photoelectric conversion means (5), for example, a first signal storage device (7a) for storing an output signal when the light source (3) is irradiated and an output signal when the light source (4) is irradiated are A second signal storage device (7b) for storing and a subtraction device for reproducing the signals stored in the both signal storage devices (7a), (7b) in synchronization with each other to grasp the level difference or cancel the output signal. (8), a calculation device (9) for calculating a shape signal from the difference between the output signals or the absolute value of the output signal difference obtained by the subtraction device (8), and the calculation device (9). The shape signal is compared with a preset reference signal, and the judgment signal is output and displayed. In the present invention, however, the light sources (3) for alternately irradiating the object to be inspected from different directions,
Particular consideration is given to (4) and the arrangement of the photoelectric conversion means (5) for picking up the image of the irradiation surface from above vertically and converting it into an electric signal. That is, as shown in plan view in FIG. 2, an extension line (11a) of the line (illumination line) connecting the light source (3) and the photoelectric conversion means (5), the light source (4), and the photoelectric conversion means (5). The light sources (3), (4), and (4) so that the extension lines (11b) of the lines (illumination lines) connecting the lines intersect with the sides of the printed circuit board (2) that is the object to be inspected. The photoelectric conversion means (5) is especially arranged.

Next, details of the electronic component mounting inspection method of the present invention having the above configuration will be described. First, the printed circuit board (2) as an object to be inspected is placed on the support base (1), one light source (3) is turned on, and the printed circuit board (2) surface is irradiated. Next, the photoelectric conversion means (5) of this light irradiation surface, for example, a television camera, captures an image from vertically above, converts it into an electric signal, and stores it in the first signal storage device (7a). After that, the light source (3) is turned off while the other light source (4) is turned on, the same image of the light irradiation surface is picked up, and the photoelectric conversion means (5) converts the electric signal into an electric signal, which is the second signal storage device. Store it in (7b). By the way, in the present embodiment, the electronic components (2
a) is mounted so that the ridgelines or generatrix of these electronic components (2a) are parallel or orthogonal to the sides of the substrate (2b), and the light irradiation from the light sources (3) and (4) is
This is done from the direction inclined with respect to the ridgeline and the generatrix of the mounted electronic component (2a). Therefore, for example, a portion that was a shadow image (image) when illuminated by the light source (3) does not show the above image when illuminated by the light source (4),
Although it is thin even if it is presented, the portion which did not present an image when the light source (3) irradiates the light presents an image on the contrary. By calculating the difference between the value of the electric signal obtained by converting the image obtained by the light irradiation from the light source (3) and the value of the electric signal obtained by converting the image obtained by the light irradiation from the light source (4). , The electric signal values corresponding to the parts of the electronic component (2a) or the like whose output signals have the same level are canceled out, and only the electric signal values corresponding to the shadow portions formed separately by the respective irradiations remain. The shape of the electronic component (2a) can be known by further performing arithmetic processing based on the coordinate value of the boundary of the presence or absence of the electric signal. For example, when the extension lines (11a) and (11b) connecting the light sources (3) and (4) and the photoelectric conversion means (5) are inclined at 45 degrees with respect to the sides of the substrate (2b), respectively, The image (image) of the part (2a ') is a light source (3) as shown in FIG.
It is made from the image (12a) when illuminated by the light and the image (12b) when illuminated by the light source (4). It should be noted that almost no image appears in a portion such as a circuit pattern that does not protrude from the surface of the substrate (2b), and even if it appears, it is offset in the level difference grasping step described later. Image (image) of the electronic component (2a) of the printed circuit board (2)
Are converted vertically into electric signals by photoelectric conversion means (5) and stored in the first signal storage device (7a) and the second signal storage device (7b) respectively, and the next subtraction device (8). Are reproduced synchronously at and the difference (level difference) between both output signals is obtained. That is, the first and second signal storage devices (7
Each output signal stored in a) and (7b), for example, output signal f _A (x, y) when light is emitted from the light source (3) for the image shown in FIG. 3 and light is emitted from the light source (4) Output signal f _B (x, y) or the absolute value of the difference | f _A (x, y) −f
_B (x, y) | is calculated by the subtraction device (8). The level difference thus obtained is calculated as a shape or position signal by the following calculation device (9). For example, in FIG. 3, a line (1
Since the above | f _A (x, y) −f _B (x, y) | along 3) exhibits the signal intensity distribution as shown in FIG. 4, the position of the inner veri in the signal intensity distribution x ₁ , x _2, ie it is found position of the electronic component. Meanwhile the average value ₁ of the parallel lines (13) by sequentially translating each time seek x _1, x ₂ which x _1, x _{2, 2} to give, this x-axis coordinates of the electronic component (2a ') Becomes Similarly, for y, the position is known from y ₁ , y ₂ , and further ₁ ,
By obtaining ₂ (y-axis position coordinate), the shape of the mounted electronic component (2a) can be known. Thus, the shape signal or the position signal calculated by the calculation device (9) is compared and judged by the judgment device (10) in which the reference value (setting value) is stored beforehand and the judgment result is displayed. The reference image (setting value) stored in advance in the determination device (10), that is, the reference image of the electronic component (2a) that is the object of the mounting inspection, binarizes a contour image, a shadow image, or a shadow image of the corresponding electronic component. Images or parts of them, such as the contour image (1
It may be part of 4). In addition, in the comparison determination by the determination device (10), the inner velocities x ₁ and x ₂ and y ₁ and y ₂ of the signal intensity distribution are obtained and compared as described above, and the signal intensity distribution (image) is stored in advance. The position of the electronic component (2a) can be detected from the matching state by directly comparing with a certain reference image (in this case, the calculation by the calculation device (9) is unnecessary).

Further, in the comparison judgment in the judgment device (10), as shown in FIG. 6, the reference image (set value) stored in advance, that is, the outline image (14), the image, and the image of the reference electronic component are binarized. electronic components by calculating the image or coincidence degree between the inner Beri x _1, x ₂ and y _1, y ₂ of the operational shape signal to the position signal by the arithmetic unit while moving a portion thereof (9) The abnormal shape can be easily detected. That is, the greater the match between the inner verities in the reference image and the inner verities calculated by the mounted electronic parts, the higher the maximum matching value. Since the maximum value of is abnormally low, the shape abnormality can be easily detected. However, the shape abnormality is detected by calculating the signal intensity distribution using a reference image (reference electronic component without calculating the degree of coincidence of the shape signal or the position signal with the verities x ₁ , x ₂ and y ₁ , y _2). The contour abnormality can be determined from the degree of matching. For example, whether the intensity width of the signal intensity distribution of the mounted electronic component is wider or narrower than that of the reference contour image corresponds to whether the mounted electronic component is high or low in the height direction, and it can be determined that the shape is abnormal.

In the above-mentioned embodiment, the electronic component is mounted on the printed circuit board (2) which is the object to be inspected so that the ridge line or the generatrix of the electronic component is orthogonal or parallel to the side of the substrate (2b),
Although they are arranged, the point is that the ridgelines or busbars of the mounted electronic components are aligned in a certain direction. Further, although two light rays are applied to the printed circuit board (2), one light source may be used and the light may be emitted from two directions by switching with a rotating mirror, for example. The present invention is not limited to this, and may be performed from multiple directions such as three directions or four directions. In this case, for example, the signal output difference when light illuminated from three directions is _{2f A (x, y) -f} B (x, y) -f C (x, y) is calculated in the form of. However, the light irradiation is not limited to turning on and off the light source by a switch, and may be performed by a selective light-shielding method using an optical shutter or an electric shutter using polarized light, or by providing a difference in intensity of irradiation light. The means (5) for picking up and photoelectrically converting the image (image) of the light irradiation surface of the printed circuit board (2) is not limited to the television camera but may be a semiconductor photoelectric conversion element or the like. Therefore, the light sources for radiating from at least two directions are symmetrically arranged with respect to the photoelectric conversion means (5). In addition, the photoelectric conversion means (5) and the light source (3),
The arrangement with (4) is also an extension line (11a) connecting them,
The angle (11b) is preferably about 45 degrees with respect to the side of the substrate (2b), that is, the electronic component (2a) arranged in a certain direction, but is not necessarily limited to this. Further, the support base (1) on which the printed circuit board (2) to be inspected is placed is a table movable in the XY axis directions, and the printed circuit board (2) is used for inspection.
The required mounting inspection can be performed by appropriately changing the position of.

〔The invention's effect〕

As described above, according to the present invention, the illumination line (the line connecting the light source and the photoelectric conversion means) is provided on the printed circuit board on which the electronic component is mounted with the ridgeline or the generatrix of the electronic component oriented in a certain direction. The light source is arranged so as to be inclined with respect to the arrangement direction. Therefore, a recognizable image (image) can be easily obtained with certainty for each electronic component without changing the illumination line for each electronic component to be mounted and inspected. Therefore, the positions of the electronic components can be easily detected only by obtaining the in-verify positions ₁ , ₂ , ₁ , _2, etc. of the images of the electronic components calculated in the subsequent image processing on the output signal by the photoelectric conversion means. In addition, the internal verification values x ₁ , x ₂ , y ₁ are calculated by calculating the image (image) of the electronic component detected while moving the reference image (set value) such as the outline image of each electronic component stored and stored in advance. , y ₂ and the like, it is possible to detect an abnormal shape of the mounted electronic component (for example, one having a damage defect, an error in the product type). Thus, according to the electronic component mounting inspection method of the present invention, the mounting state of electronic components can be inspected reliably and highly accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an electronic component mounting inspection method of the present invention, and FIG. 2 is a plan view showing an arrangement relationship of a light source and photoelectric conversion means with respect to a printed circuit board in FIG.
FIG. 3 is a copy diagram showing an image of an electronic component obtained in the apparatus of FIG. 1, FIG. 4 is a characteristic diagram showing signal intensity in the x-axis direction in the image of FIG. 3, and FIG. 5 is FIG. 6 is an imitation diagram showing an example of reference values (images) stored and stored in advance in the apparatus of FIG. 6, and FIG. 6 is an explanatory diagram showing an example of operation in the apparatus of FIG. (1): support, (2): printed circuit board, (2a): electronic component, (2b): substrate, (3), (4): light source, (5):
Photoelectric conversion means, (6): image processing device, (11a), (11b): extended line connecting the light source and the photoelectric conversion means.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-60-140107 (JP, A) JP-A-52-63753 (JP, A) JP-A-55-155205 (JP, A) JP-A-59- 107202 (JP, A)

Claims (1)

[Claims] 1. A step of placing a printed circuit board on which a ridgeline or a generatrix of a mounted electronic component is arranged in a fixed direction on a support base, and light from a light source with respect to the direction of the ridgeline or the generatrix. A step of irradiating the electronic component from a direction opposite to each other through a photoelectric conversion means for inclining and imaging the image of the electronic component from above, and a shadow image of the electronic component due to light irradiation from the light source from above An electronic component mounting inspection method comprising: a step of capturing an image and converting it into an electric signal by the photoelectric conversion means; and a step of image-processing an output signal output by the photoelectric conversion means by an image processing device.