JPH0375506A - Inspecting apparatus for mounting of printed board - Google Patents

Abstract

PURPOSE:To improve the ratio of automation by providing a rechecking and judging circuit and an area limiting circuit, limiting an inspecting area, and comparing a profile pattern with a reference pattern. CONSTITUTION:A rechecking and judging circuit 7 and an area limiting circuit 8 are provided in this apparatus. When collating with a reference pattern is performed highly accurately in a collation circuit 6, the data of a height and a position of a component are directly outputted from the circuit 7. When it is judged that the collation is impossible, a retry instruction is outputted from the circuit 7 to the circuit 8. When the retry instruction is received in the circuit 8, an area for rechecking for the upper surface of a board as an object is set. Then, a histogram is formed based on the rechecking area in a data analyzing circuit (high and low data) 4, and the height and the like of the component are computed. The peak on the side of the high level in the histogram is made clear. Thus, the adequate slice level is obtained. The profile pattern created in a binary-coding circuit 51 approaches the outer shape of the component, and highly accurate collation with a reference pattern can be performed.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an inspection device for a printed circuit board in which components are mounted on a board, particularly a printed circuit board mounting inspection device for inspecting the component mounting position and mounting height, and is capable of highly accurate alignment with a reference pattern. The aim is to provide a printed circuit board mounting inspection device that automatically re-inspects samples that cannot be verified and increases the automation rate. A signal processing circuit that forms height information from an imaging signal, an information analysis circuit that calculates the height of a component mounted on a specimen to be inspected from the height information, and a graphics circuit that creates a contour pattern of each component from the height information. The present invention is configured to include: a matching circuit that matches the contour pattern with a corresponding reference pattern; a reexamination discrimination circuit that limits the inspection area and compares the contour pattern and the reference pattern; and an area limiting circuit.

[Industrial application field]

The present invention relates to an inspection device for a printed circuit board in which components are mounted on a board, and particularly to a printed circuit board mounting inspection device for inspecting component mounting positions and mounting heights.

In recent high-density printed circuit boards, many chipped circuit components, such as resistance elements and capacitors, are mounted on the same board, but the mounting positions of these circuit components (hereinafter referred to as components) are Some of them may shift or come up during soldering and deviate from the predetermined mounting height.

In the conventional printed circuit board inspection process, the number and type of components mounted on the board were relatively small, so inspectors inspected the component mounting position and mounting height with the naked eye. In modern printed circuit boards where many components are mounted, it is extremely difficult to visually inspect the component mounting position and mounting height. Therefore, a printed board mounting inspection device that automatically performs such inspection has been developed.

[Conventional technology]

FIG. 3 is a block diagram showing a conventional inspection device, FIG. 4 is a schematic diagram showing an example of a measurement optical system, and FIG. 5 is a diagram explaining the operation of the conventional inspection device.

In Fig. 3, the conventional inspection device that inspects the component mounting position and mounting height includes a measurement optical system 2 that images the inspected sample 1 and outputs an image signal, and forms height information corresponding to the unevenness of the sample surface. A signal processing circuit 3, an information analysis circuit 4 that calculates the height of the component 11 mounted on the sample to be inspected 1, a graphics circuit 5 that creates a contour pattern of the component at an arbitrary slice level, and a contour pattern It is comprised of a matching circuit 6 that matches the corresponding reference pattern.

The sample to be inspected 1 is mounted on a stage 21 on which the sample to be inspected 1 is placed, as shown in FIG. , a light irradiation system 23 that irradiates the specimen 1 to be inspected with a laser beam 22 scanned in a direction perpendicular to the plane of the paper, and a light observation system 24 that observes the laser beam 22 reflected by the specimen 1 to be inspected from an oblique direction. The optical observation system 24 includes an imaging lens 25 and a light spot position detection sensor 26.

The signal processing circuit 3 forms height information corresponding to the unevenness of the sample surface and brightness information corresponding to the brightness based on the imaging signal output from the light spot position detection sensor 26. The signal processing circuit 3 includes a height information memo "J31" and a bright/dark information memory 32, and the height information is stored in the height information memory 31.
The brightness information is stored in the brightness information memo 1732, respectively.

The information analysis circuit 4 includes a distribution map creation circuit 41 that cuts out an inspection window and creates a height histogram, and a height determination circuit 42 that calculates the component height and slice level from the histogram.
has. FIG. 5(a) is an example of an inspection window cut out from the height information representing the whole sample to be inspected.
etc. are included.

5) is an example of a histogram created by the distribution map creation circuit 41, in which the horizontal axis represents the height level and the vertical axis represents the frequency at that level. In the figure, the peak on the low level side is the substrate, the high level The side peak is the upper surface of the component, and the area between the high level side peak and the low level side peak corresponds to the height of the component. Therefore, when creating a contour pattern for each component, if the slice level for binarizing the height information is set to 50% of the component height, the slice level will be the middle between the two peaks (indicated by the - dotted chain line).

The graphics circuit 5 includes a binarization circuit 51 that binarizes the height information at the slice level to create a contour pattern of the part to be inspected, and the created contour pattern is stored in a contour figure memory 52. .

FIG. 5(C) is an example of a contour pattern, and when the peak on the high level side of the histogram is clear, an appropriate slice level is obtained and a contour pattern 11a close to the outer shape of the part is created.

The matching circuit 6 includes a dictionary memory 61 that stores reference patterns llb, and the outline patterns lla of the parts to be inspected stored in the outline figure memory 52 are combined with the corresponding reference patterns 11b as shown in FIG. 5(A). It is compared with As a result, information related to the height of the component is output from the height determination circuit 42, and information related to the mounting position of the component is output from the verification circuit 6.

[Problem to be solved by the invention]

FIG. 6 is a diagram showing problems in the conventional inspection device.

As mentioned above, if the peak on the high level side of the histogram is clear, an appropriate slice level can be obtained and the contour pattern will be l
Since the outer shape is close to that of the la component, no error will occur when comparing with the corresponding reference pattern llb. However, if there is a lot of solder for mounting around the part to be inspected, the peak on the high level side of the histogram becomes unclear, as shown in Figures 6(a) and (c).
The slice level may be set to a high level as shown in FIG. 6(a), or may be set to a low level as shown in FIG. 6(b).

For example, when the slice level is set to a high level as shown in FIG. 6(a), the contour pattern lla of the created part to be inspected is small as shown in FIG. 6(C), and the slice level is set to a high level as shown in FIG. ), the created contour pattern lla of the part to be inspected is large as shown in FIG. 6(d), and the matching circuit cannot match it with the reference pattern llb with high precision. In extreme cases, there is a problem in that matching with the reference pattern becomes impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printed circuit board mounting inspection apparatus that automatically re-inspects a sample that cannot be highly accurately matched with a reference pattern, thereby increasing the automation rate.

[Means to solve the problem]

FIG. 1 is a block diagram showing an inspection apparatus according to the present invention. The same objects are represented by the same symbols throughout the figures.

The above-mentioned problems include a measurement optical system 2 that images the specimen 1 to be inspected and outputs an imaging signal, a signal processing circuit 3 that forms height information of the sample surface from the imaging signal, and a component 1 mounted on the specimen 1 to be inspected.
1, an information analysis circuit 4 that calculates the height of each part 11 from height information, a graphics circuit 5 that creates an outline pattern of each part 11 from the height information, and a matching circuit 6 that matches the outline pattern with a corresponding reference pattern. This is achieved by the +ffl mounting inspection apparatus of the present invention, which comprises a re-examination discrimination circuit 7 for limiting the inspection area and comparing the contour pattern and the reference pattern, and an area limiting circuit 8.

[For production]

In Figure 1, a re-examination discrimination circuit and an area-limiting circuit are installed in the printed board mounting inspection device, and by limiting the inspection area and comparing the outline pattern and the reference pattern, samples that cannot be accurately matched are automatically re-examined. Thus, it is possible to realize a printed board mounting inspection apparatus that enables the automation rate to be increased.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that FIG. 2 is a diagram for explaining the operation of the device according to the present invention.

As shown in FIG. 1, the device according to the present invention is equipped with a retest discrimination circuit 7 and an area limiting circuit 8, and is capable of limiting the area for samples that cannot be compared with a reference pattern or samples with low accuracy during matching. It differs from conventional equipment in that it performs a re-inspection. That is, when the matching circuit 6 performs matching with the reference pattern with high accuracy, the height information and position information of the part are output as they are from the retesting determination circuit 7, but it is determined that matching with the reference pattern is impossible. If there is a need to further improve accuracy, the retest determination circuit 7 outputs a retry command to the area limiting circuit 8.

The area limiting circuit 8 includes an area setting circuit 81 and a re-examination area mask 82.
When a retry command is input, a re-inspection area is set that targets only the top surface of the board 12 and parts 11, as shown by diagonal lines in FIGS. 2(a) and 2(b). . The information analysis circuit 4 creates a histogram based on the re-inspection area, and calculates the component height and slice level in the same way as in the first inspection.

In the re-examination area, areas forming irregular irregularities such as band 13 are excluded, and the histogram created by the distribution map creation circuit 41 has a clear peak on the high level side, as shown in FIG. 2(C). This will give you a suitable slice level. In addition, the contour pattern created in the binarization circuit 51 becomes close to the outer shape of the component, as shown in FIG. 2(d), so that highly accurate matching with the reference pattern is possible.

In this way, by installing the re-examination discrimination circuit and the area-limiting circuit in the printed circuit board mounting inspection equipment, limiting the inspection area and comparing the outline pattern with the reference pattern, it is possible to automatically re-inspect parts that cannot be verified with high accuracy. It is possible to realize a printed board mounting inspection device that enables inspection and increases the automation rate. Note that the re-setting of the horizontal area is performed based on the position information previously output from the collation circuit, and there is no need to input the information again, so the inspection time for the printed board does not increase significantly.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a printed circuit board mounting inspection apparatus that automatically re-inspects a sample that cannot be highly accurately matched with a reference pattern, thereby further increasing the automation rate.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an inspection device according to the present invention, Fig. 2 is a diagram explaining the operation of the device according to the present invention, Fig. 3 is a block diagram showing a conventional inspection device, and Fig. 4 is a measurement optical system. FIG. 5 is a schematic diagram showing an example of the system, FIG. 5 is a diagram explaining the operation of a conventional inspection device, and FIG. 6 is a diagram showing problems in the conventional inspection device. In the figure, 1 is a sample to be inspected, 3 is a signal processing circuit, 5 is a graphic circuit, 7 is a retest discrimination circuit, 11 is a component, 13 is solder, 32 is a brightness information memory, 42 is a height judgment circuit, and 52 is a height judgment circuit. 81 represents a contour figure memory; and 81 represents an area setting circuit. 2 is a measuring optical system, 4 is an information analysis circuit, 6 is a collation circuit, 8 is an area limiting circuit, I2 is a board, 31 is a height information memory, 41 is a distribution map creation circuit, 51 is a binarization circuit, 61 is a dictionary Memory, 82 is a re-examination area mask, (0) (1)) (C) (cl) Figure 1 is a block diagram showing the inspection device according to the present invention; 2
A block diagram showing the equipment for testing wear and tear (Figure (α) ())) Height (d) Figure (α) (b) Millet diagram showing "The battle of measurement L# system" (Q) (1)) Island level (e) (Self) One net 01 folds and 2 Figure 1 shows the problem layer to be solved.

Claims (1)

[Claims] A measurement optical system (2) that images the sample to be inspected (1) and outputs an image signal; a signal processing circuit (3) that forms height information of the sample surface from the image signal; an information analysis circuit (4) that calculates the height of the mounted component (11) from the height information; a graphic circuit (5) that creates a contour pattern of each component (11) from the height information; A matching circuit (6) that matches the contour pattern with the corresponding reference pattern
), a reexamination discrimination circuit (7) for limiting the inspection area and comparing the outline pattern and the reference pattern, and an area limiting circuit (
8) A printed board mounting inspection device comprising: