JPS6318206A - Apparatus for inspecting mounting of electronic part - Google Patents

Abstract

PURPOSE:To detect the mount position error of a mounting part with high reliability, by arranging a light source so that an illumination line is inclined in a part arranging direction with respect to a substrate having the ridgeline or bus bar of each electronic part arranged thereto in a definite direction. CONSTITUTION:The electronic parts 2a of a printed circuit board 2 are mounted so that the ridgeline or bus bar or each of said parts is parallel to the side 2b of the board 2 or crosses said side 2b at a right angle and the extending lines respectively connecting light sources 3, 4 and a photoelectric converter means 5 are respectively arranged so as to be inclined, for example, at an angle of 45 deg. with respect to the side 2b. When each part 2a is alternately irradiated with lights from the light sources 3, 4, the picked-up image on the irradiated surface is converted to an electric signal by the photoelectric converter means 5 to be respectively stored in first and second signal memory devices 7a, 7b and synchronously regenerated by the next subtraction apparatus 8 to calculate the difference between both output signals. This level difference is operated by an operation apparatus 9 to obtain shape and position signals. These signals are compared and judged by a judge apparatus 10 having a reference value preliminarily stored therein and the positional error of each part 2a or the abnormality of the shape thereof is detected. By this method, the mounting state of the electronic parts 2a can be certainly examined with high accuracy by a simple image processing.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an electronic component mounting inspection apparatus.

(Prior art) After mounting electronic components, such as resistors and capacitors, on a printed circuit board (electronic component mounting).

The following methods have been proposed to inspect the implementation status. That is, a printed circuit board on which electronic components such as capacitors are mounted is irradiated with oblique light alternately from two directions, and an image obtained is converted to photoelectric conversion means.

For example, a means has been developed to detect the position and shape of mounted electronic components by capturing images with a television camera and converting them into electrical signals and processing the images with a XX machine (Japanese Patent Laid-Open No. 55-15
5205 Publication).

Although the above-mentioned mounting detection means can easily inspect and detect the mounting state of electronic components, it is difficult to say that it is fully satisfactory in terms of accuracy and reliability. In other words, when performing a mounting inspection on a printed circuit board on which a large number of electronic components are mounted, the image obtained by alternately irradiating the oblique light beams may be slightly unclear, and the inspection may take a long time. There were also problems with reliability.

(Problems to be Solved by the Invention) Therefore, the present invention uses simple image processing to reliably detect and inspect errors in the mounting position of mounted electronic components and abnormalities in the shape of the components. The purpose is to provide a mounting inspection device.

[Structure of the invention]

(Means for Solving the Problems) According to the present invention, a printed circuit in which electronic components are arranged such that the ridge lines or generatrix lines of the electronic components are arranged in a certain direction, for example, parallel to or perpendicular to the sides of the board. m (illumination line) connecting a light source that irradiates light to the substrate from at least two directions and a photoelectric conversion means that captures an image (image) obtained by irradiating light from this light source and converts it into an electrical signal.
The main point is to arrange the light α and the photoelectric conversion means so that the extension line thereof is inclined with respect to the arrangement direction of the electronic component.

(Function) With the above configuration, the image or image appearing on the printed circuit board outputs a constant output signal by light irradiated from at least two directions. That is, since the mounted electronic components are always irradiated with light from an oblique direction with respect to their ridges or generatrix lines, all electronic components exhibit a predetermined image or image. Therefore, the output from the photoelectric conversion means is uniform for the mounted electronic part convex metal, thereby improving the reliability of inspection of the mounted parts. Further, by comparing the output with an electrical signal (image processing) while moving a pre-stored reference image of the electronic component, it is also possible to detect whether the electronic component has an abnormal shape.

(Example) The present invention will be described below with reference to FIGS. 1 and 2 showing examples of the present invention. In Fig. 1, (1) is a support stand;
(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 table (1). However, the printed circuit board (2) is...

For example, electronic components (2a) such as resistors, capacitors, semiconductor elements, etc. are arranged and mounted such that the crests or busbars of each electronic component (2a) and the sides of the substrate (2b) are parallel or perpendicular to each other. It is something. Also (3),
(4) is a light source, such as a lamp, that alternately irradiates light from different directions to the printed circuit board (2), and these light sources (3) and (4) are
The irradiation intensity on the irradiated surface is approximately the same. (5) connects the printed circuit board (2) to the light source (3), (
4) The photoelectric conversion means 1 is, for example, a television camera, which captures images obtained by alternately irradiating the light and converts them into electrical signals. Furthermore, (6) is a means for image processing the output signal outputted from the photoelectric conversion means (5), and is constructed as follows. That is, the signal 1 outputted by the photoelectric conversion means (5), for example, the first signal storage device (7a) that stores the output signal when the light source (3) is irradiated, and the output signal when the light source (4) is irradiated. a second signal storage device (7b) for storing;
and a subtraction device R (8) which synchronizes and reproduces the signals stored in both signal storage devices (71) and (7b) to grasp the level difference or cancel out the output signals.

and a determination device (1G) that compares the shape signal calculated by the calculation device 1 (9) with a preset reference signal and outputs and displays a determination signal. Particular consideration has been given to the arrangement of the light source (33, (4)) that alternately irradiates the object to be inspected from different directions and the photoelectric conversion means (5) that captures an image of the irradiated surface and converts it into an electrical signal. That is, as shown in plan in FIG. ) Extension line (llb) of the line (illumination line) connecting
the light sources (3), so that the light sources (3) cross each other at an angle with respect to the side of the printed circuit board (2) which is the object to be inspected;
(4) and photoelectric conversion means (5) are particularly provided.

Next, the operation of the electronic component mounting inspection apparatus having the above configuration will be explained. First, a printed circuit board (2) as an object to be inspected is placed on a support stand (1), and one light source (3) is turned on to illuminate the surface of the printed circuit board (2). Next, an image of this light irradiated surface is captured by a photoelectric conversion means (5), for example, a television camera,
It is converted into an electrical signal and stored 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, and an image of the light irradiation surface is similarly captured and converted into an electrical signal by the photoelectric conversion means (5), which is then stored in the second signal storage device. (7b). By the way, in this embodiment, the electronic components (2a) of the printed circuit board (2) are mounted such that the crests or busbars of the electronic components (2a) are parallel or perpendicular to the sides of the board (2b). , and the respective light irradiation from light sources (+3) and (4) will be performed from a direction inclined to the ridge lines and generatrix lines of the mounted electronic components (2).Therefore, for example, light source (3) The part that was a shadow (image) when irradiated with light source (4) did not exhibit the above-mentioned image, or even if it did, it was faint, whereas it did not exhibit a shadow image when irradiated with light from light source (3). For example, if the extension lines (11a) and (ob) connecting the light sources (3) and (4) and the photoelectric conversion means (5), respectively, are connected to the substrate (
If each side is inclined at 45 degrees with respect to the sides of 2b),
As shown schematically in Figure 3, the image (image) of the electronic component (2a) is an image (12b) when irradiated with light source (3) and an image (12b) when irradiated with light source (4). It will be made from.

Note that for parts such as circuit patterns that hardly protrude from the surface of the board (2b), almost no image is produced, but even if it appears, it will be canceled out at the stage of understanding the level difference, which will be described later. The images of the electronic components (2a) of the printed circuit board (2) are each converted into electrical signals by a photoelectric conversion means (5), and are transferred to a first signal storage device t (7a).

The signals are respectively stored in the second signal storage device (7b) and synchronously reproduced in the next subtraction device (8) to determine the difference (level) between the two output signals. That is, each output signal stored in the first and second signal storage devices e (7a) and (7b), for example, the output signal fA ( x, y) and the output signal fn(x, y) when irradiated with light by the light source (4) or the absolute value of the difference l f person(x, y) - fn(x, y
) Find l using the subtraction device (8). The level difference thus obtained is calculated into a shape or position signal by the next calculation device (9). For example, in Figure 3, the above 1f people (x, y) - fn (x, y) I along the line αJ parallel to the X axis
exhibits a signal strength distribution as shown in FIG.
c! In other words, the position of the electronic component can be found. - direction The parallel lines 03 are sequentially translated and x1+X is obtained each time, and the average value of xl t xt is obtained, which becomes the X-axis position coordinate of the electronic component (2a). Do the same for y)'l r yt to find the position, and then Y1
By obtaining +Yz (y-axis position coordinate), the shape of the mounted electronic component (2a) can be found. The shape signal or position signal thus calculated by the calculation device (9) is compared and determined by the determination device Ql which stores reference values (setting values) in advance, and the determination results are displayed. Note that the reference image (set value) stored in advance in this judgment device o(ll),
That is, the reference image of the electronic component (2a) to be inspected for mounting is a contour image, an image, a binarized image of the corresponding electronic component, or a part thereof, for example, one of the contour images αa as shown in FIG. It can also be a department. In addition, in the comparison judgment by the judgment device 0C, the inner deviation of the signal strength distribution xI +
It is also possible to detect the position of the electronic component (2a) from the matching situation by directly comparing the signal intensity distribution (image) with a reference image stored in advance, without determining and comparing Xt and )'1 + Yt ( In this case, the calculation by the calculation device (9) becomes unnecessary).

Furthermore, in the comparison judgment in the judgment device OQ, the sixth
As shown in the figure, the reference image (setting value) is stored in advance.
In other words, while moving the outline image (14° image, binarized image, or a part thereof) of the electronic component that serves as a reference, l + X2 and 'h, Yx
Abnormalities in the shape of electronic components can also be easily detected by calculating the degree of matching. In other words, the more the inner periphery in the reference image matches the inner periphery calculated for the mounted electronic component, the higher the maximum value of the 1 degree of coincidence will be. However, if the mounted electronic component is damaged or has an abnormal shape, the above coincidence degree will increase. Since the maximum value of is abnormally low, shape abnormalities can be easily detected.

However, detection of abnormalities in the shape of the lever is possible only within the above shape signal or position signal! J xl + Vine. For example, whether the intensity width of the signal intensity distribution of a mounted electronic component is wider or narrower than the reference contour image depends on whether the mounted electronic component is taller or lower in the height direction.

It is determined that the shape is abnormal.

In the above embodiment, the printed circuit board (2) which is the object to be inspected is They were mounted and arranged so that they were perpendicular or parallel to the sides of the board (2b), but the light source was one, and for example, a rotating mirror was used to switch and emit light from two directions. Alternatively, light irradiation may be performed not only from two directions but from many directions such as three or four directions. In this case 1. For example, when light is irradiated from three directions ((, the signal output difference is 2f people (x, y) - fn (x,
y) −fo(x, y). The above-mentioned light irradiation is not limited to turning on and off the light source using a switch, but may also be performed selectively using an optical shutter or an electric shutter using polarized light, or by varying the intensity of the irradiated light. Also, a means (5) for capturing an image of the light-irradiated surface of the printed circuit board (2) and photoelectrically converting it.
is not limited to a television camera, but may also be a semiconductor photoelectric conversion element or the like.

Although it is preferable that the light source emitting light from at least two directions is arranged symmetrically with respect to the photoelectric conversion means (5), the present invention is not limited thereto. photoelectric conversion means (5) and light source (3),
The arrangement with (4) is also an extension line that connects them to each other.
(llb) is preferably inclined at about 45 degrees with respect to the electronic component (2a) disposed on the side of the substrate (2b), that is, in a certain direction, but is not necessarily limited to this. Furthermore, a support stand (1) on which a printed circuit board (2), which is the object to be inspected, is placed.
is a table movable in the XY-axis directions, and the position of the printed circuit board (2) is appropriately changed during inspection to perform the required mounting inspection.

〔Effect of the invention〕

As described above, according to the present invention, the illumination a (the line connecting the light source and the photoelectric conversion means) is connected to the printed circuit board on which the ridge line or bus line of the child component is oriented in a certain direction and the electronic component is mounted. The light source is arranged at an angle with respect to the direction in which the electronic components are arranged. Therefore, it is possible to easily obtain clearly visible images of each electronic component without changing the illumination line for each convex side of the electronic component to be inspected for mounting. Therefore, the inner edge value is calculated by calculating the image (image) of the electronic component detected while moving the reference image (setting value) such as the outline image of each electronic component, which is stored in advance in the output signal from the photoelectric conversion means. xl *”! r
It is also possible to detect an abnormal shape of a mounted electronic component (for example, an incorrect type of one with a breakage defect) based on the degree of coincidence with Yl + Yt. Thus, according to the electronic component mounting inspection apparatus according to the present invention, the mounting state of electronic components can be inspected reliably and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the electronic component mounting inspection apparatus of the present invention, FIG. 2 is a plan view showing the arrangement relationship of the light source and photoelectric conversion means with respect to the printed circuit board in FIG. 1,
Fig. 3 is a reproduction diagram showing the image of the electronic component obtained with the apparatus shown in Fig. 1, Fig. 4 is a characteristic diagram showing the signal strength in the X@ direction in the image of Fig. 3, and Fig. 5 is the diagram shown in Fig. FIG. 6 is an explanatory diagram showing an example of the operation of the apparatus shown in FIG. 1. FIG. (1) Two support stands, (2): Printed circuit board, (2a): Electronic components. (2b): Substrate, (3), (4): Light source, (5)
: Photoelectric conversion means. (6) Dual image processing device. (lli, (llb): An extension line connecting the light source and the photoelectric conversion means. Agent Patent attorney Nori Chika Ken Yudo Kikuo Takehana 1fi'@4 Figure 2d Figure 5 Figure 6

Claims (2)

[Claims] (1) A support stand on which a printed circuit board is placed, on which the ridge lines or bus bars of the mounted electronic components are arranged in a certain direction;
a light source that irradiates the printed circuit board with light from at least two directions; a photoelectric conversion unit that captures an image of the electronic component caused by the light irradiation from the light source and converts it into an electrical signal; and an output output by the photoelectric conversion unit. an image processing device that performs image processing on a signal, and the light source and the photoelectric conversion means are arranged such that an extension line connecting the light source and the photoelectric conversion means is inclined with respect to a direction in which the electronic component is arranged. An electronic component mounting inspection device characterized by comprising: (2) The image processing device performs image processing on the output signals alternately outputted by the photoelectric conversion means, and compares the degree of matching with the output image while moving a pre-stored reference image of the mounted electronic component or a part thereof. An electronic component mounting inspection apparatus according to claim 1, characterized in that the electronic component mounting inspection apparatus includes means for performing.