JPS63153412A - Packaging component inspecting instrument - Google Patents

Abstract

PURPOSE:To exactly detect the shape of component whose reflection factors are different, by obtaining a height data, based on two kinds of luminance data based on optical cut images obtained from two directions and two large and small reference levels, at the time of inspecting the packaging state of packaging component by using an optical cutting method. CONSTITUTION:By two line sensors 8, 9, two kinds of optical cut images are detected from two directions, two kinds of (first and second) height data and luminance data based thereon are obtained, and by using these data, a three- dimensional shape data is obtained. In such a packaging component inspecting instrument, when one of first and second luminance data is above a first reference level (corresponding to the level of noise) SL1, and also, the other is above a second reference level (corresponding to a saturation level of the line sensor (SL2, a height data corresponding to a smaller luminance data is selected, and in other case, a height data corresponding to a larger luminance data is selected.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a mounted component inspection device that inspects the mounting state of a mounted component using a light cutting method, which uses two types of brightness based on light cut images obtained from two directions. By determining the size of the data based on two reference levels and obtaining appropriate height data according to the determination result, it is possible to detect highly reflective metal parts or metal parts on the object to be inspected. Even in cases where low-profile black parts are included, the shape of these parts can be detected accurately.

[Industrial application field]

The present invention relates to a mounted component inspection device that automatically inspects the mounting state of electronic components (particularly dip-type components) mounted on, for example, a printed circuit board or a hybrid IC using an optical cutting method.

In recent years, surface-mounted components (chip components) have come into widespread use in order to miniaturize electronic devices. It is predicted that the use of chip components will continue to advance and the number of chips will increase rapidly in the future. In the manufacturing process of printed circuit boards using chip components, mounting is performed by automatic machines. However, automation of the external appearance inspection of the mounted state has been delayed and currently relies on human visual inspection. Automation of visual inspection is essential to improve the reliability of printed circuit boards using chip components. Against this background, there has been a strong desire to automate the visual inspection of chip component mounting.

[Conventional technology]

Conventional mounted component inspection equipment using the optical cutting method irradiates the object to be inspected with a slit-shaped light beam from directly above.
The reflected light is detected diagonally from above with a single line sensor, the resulting two-dimensional light-cut images are combined to obtain the three-dimensional shape of the part, and this is compared with the base pattern (1B). A device is known in which the mounting state is inspected from this point of view.

However, when measuring the three-dimensional shape of a component from one direction as described above, there are locations that are in the shadow of the component Q and cannot be detected by the line sensor S, as shown in FIG.

Therefore, by using two line sensors and performing detection from two symmetrical directions with respect to the beam plane, and by combining the two types of data regarding height and brightness obtained from this, the undetectable area due to the shadow mentioned above can be eliminated. A device has been proposed that eliminates this problem (see Japanese Patent Application No. 142947/1983). As a means for the above-mentioned synthesis, the data with higher luminance (that is, the data that is assumed to be unaffected by shadows) is selected from the two types of data, and the data is converted into one type of data. It is something.

[Problem that the invention seeks to solve]

The conventional device described above, which detects from two directions, simply selects the one with higher brightness from two types of data to obtain composite data, so it is difficult to avoid the influence of shadows. However, new problems arise, such as the following: In other words, as shown in Figure 7, when a light beam hits a metal edge or a slope of solder on component Q, one line sensor SI detects extremely strong reflected light that exceeds its saturation level. As a result, accurate detection signals cannot be obtained. On the other hand, if the intensity of the light beam is shifted to a small value in consideration of these problems, the saturation of the line sensor will be eliminated, but it will not be possible to detect parts that only receive a small amount of reflected light, such as black parts. I end up.

In view of the above-mentioned problems, the present invention provides a mounted component inspection device that can eliminate the influence of shadows and can accurately detect components having metal parts with high reflectance, black components with low reflectance, etc. The purpose is to

[Means for solving problems]

The present invention detects two types of light cut images from two directions using two line sensors, and based on these, two types of (first
．． (2) A mounted component inspection apparatus that obtains height data and brightness data and uses these data to obtain three-dimensional shape data. A synthesis means is provided for selecting a more appropriate one from among the second height data to obtain synthetic height data. This synthesis means is configured such that one of the first and second luminance data is equal to or higher than a first reference level (corresponding to a noise level), and the other one is equal to or higher than a second reference level (saturation level of a line sensor). (equivalent to) or above, the height data corresponding to the smaller luminance data is selected, and at other times, the height data corresponding to the larger luminance data is selected.

[Function] In the above combining means, one of the two luminance data is equal to or higher than the first reference level, and the other is equal to or higher than the second luminance data.
When it is above the reference level, one line sensor detects strong reflected light that is above the saturation level, and the other line sensor detects appropriate reflected light that is above the noise level.
Or when strong reflected light exceeding the saturation level is detected.

In such cases, the smaller (i.e. appropriate size)
Since the height data corresponding to the brightness data of 1 or 2 (or the one closer to the appropriate level) is selected, more appropriate combined height data can be obtained.

= On the other hand, cases other than the above are when one line sensor detects strong reflected light that is higher than its saturation level and the other line sensor detects weak reflected light from the noise rail, or when both This is when a suitable or weak reflected light is detected that is less than the line sensor's saturation level. In such a case, the height data corresponding to the larger luminance data (that is, the appropriate level or the one closer to the appropriate level) is selected, so that more appropriate combined height data can be obtained.

From these facts, no matter what kind of rail foul light is detected by the two line sensors, the more appropriate height data will be selected as the composite height data. Accurate detection is also possible for parts having an anti-U=1 ratio.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an optical system (light irradiation means and light detection means) according to an embodiment of the present invention.

In the figure, laser light AI output from a semiconductor laser 1 is converted into a slit-shaped light beam p2 by a cylindrical lens 2. This light beam 12 is vertically irradiated onto a printed board P placed on a stage 3 moving in the direction of arrow A.

That is, the printed board P is scanned in the direction of arrow A by the light beam 12. The printed board P is
Various components (particularly chip components) Q are mounted on the substrate R, and optical cutting lines are formed on the substrate R and the components Q by irradiation with the light beam β2.

The above-mentioned light cutting line is cut from two symmetrical directions with respect to the beam planes of the light beams J-1 and J-2, and the two line sensors 8 and 9 are connected to each other via an imaging lens 4.5 and a vibrating mirror 6.7. Detected. Since the vibrating mirror 6.7 is vibrated at high speed within a certain angular range (for example, 190 reciprocations per second), the imaging plane of the reflected lights R3 and n4 from the light cutting line becomes a line due to the vibration. It moves back and forth on the light receiving surface of the sensor 8.9.

Therefore, the line sensors 8, 9 can obtain the entire image of the light cutting line by one swing of the vibrating mirror 6.7 in one direction.
Dimensional optical section images can be detected at high speed.

The above-mentioned photocutting image is, for example, as shown in FIG.
Symmetry of formation of optical cutting line ■ (part 01 board R)
The images are obtained as substantially band-shaped images with a shift according to the height of the object, and these are multi-gradation grayscale images with brightness according to the reflectance of the object. In addition, the stage 3, the vibrating mirror 6.7, and the line sensors 8, 9 are properly synchronized with each other so that two types of light cut images corresponding to the two detection directions can be sequentially obtained over the entire surface of the printed board P. It has become.

The two types of light cut images obtained from the two line sensors 8.9 are sequentially sent to a peak detection circuit (not shown). In the light section image shown in FIG. 2 (al), a brightness peak K as shown in FIG. 2 (bl) exists along the height direction (X direction) at each position in the X direction.

The peak detection circuit determines the height and brightness at a brightness peak K that exceeds a predetermined required level for each of the two types of light-cut images, and extracts these as height data and brightness data, respectively.

The height data and brightness data obtained in this manner accurately correspond to the height and reflectance of the detection target surface, except for the shadowed portion described above.

Next, which two types of (first and second) height data (H
1, H2) and brightness data (11°I2)
are sequentially taken in, and a synthesis process is performed to obtain one type of data without the influence of shadows as shown in FIG. The synthesis means for this purpose will be explained below.

As shown in FIG. 3, the above synthesis process first sets the luminance data obtained by the peak detection circuit to a first reference level SLI corresponding to the noise level and the saturation level of the line sensors 8 and 9. A corresponding second reference level SL2 is set. Second reference level SLI.

The brightness data level is set to A and B based on SL2.

Divide into three ranges of C. rAJ is a state in which the luminance is lower than the first reference level SLI, and is within the noise level range. rBJ, the luminance is the first reference ray, le S
This is a state where L is greater than or equal to 1 and is smaller than the second reference level SL2, which is within the appropriate level range. "C" is a state in which the luminance is equal to or higher than the second reference level SL2, and is within the saturation level range of the line sensor.

Next, the first. The second luminance data is A and B, respectively.
, C is determined. and,
(i) If one luminance data is in the range "C" and the other luminance data is in the range rBJ or rCJ, select the height data corresponding to the smaller luminance data. In addition, (ii) - If the case is other than the above, height data corresponding to the larger luminance data is selected. The height data selected here is output as composite height data Ha.

The synthesis process is performed in this way, and a specific synthesis circuit for this purpose is shown in FIG. This synthesis circuit consists of the first to
It is composed of six sixth comparator circuits (COMP) 11a to Ilf, an adder circuit (ADD) 12 of 111&, and three first to third selection circuits (SEL) 13a to 13c. Comparison circuits 11a to llf have input A and input B.
If A2B, output C is set to "1", and A<B
Then, it is a circuit that sets the output C to 0.J.Addition circuit 1
2 adds input A and input B to each other, and this added value (A
→-B) is a circuit that outputs C. Selection circuit 13a~
13c selects input A and outputs it if input S is 11''.
This circuit selects input B and outputs C if input S is "0".

In the above synthesis circuit group, first. Comparing circuits 11a respectively compare the second luminance data II and I2.

The comparison circuit 11b compares it with the second reference level S L 2, and the comparison circuits 11c and 11d compare it with the first reference level SLI. Then, depending on the results of these comparisons, the levels of the luminance data II and I2 are coded into 2-bit values. For example, regarding luminance data ■1, the comparison circuit 11
If both the outputs of a and Ilc are "1" (that is, the state of "c" in Fig. 3), the code is rBJ,
If the output of the comparison circuit 11a is "0" and the output of the comparison circuit 11c is "1" (that is, the state of rBJ in FIG. 3), the code is set to "1", and the comparison circuit 11a.

If any output of 11C is "0" (that is, the state of rAJ in FIG. 3), the code is set to "0". Regarding the other luminance data 12, the comparison circuits 11b and 1
The output of 1d is similarly encoded.

Next, as mentioned above, the first. The coded values of the second luminance data (rOJ, rlJ, r3j) are mutually added together in an adding circuit 12. In this adder circuit 12, as shown in FIG. 5, two input values A and B (=rO
6i11 according to the combination of J, Ill or "3")
i's added value C(-rOJ.

rlJ, r2J, rBJ, rAJ or "6") are obtained. Therefore, next, the above added value is converted to 1 by the comparison circuit If.
rlJ, rO depending on whether it is ``4'' or higher.
Output J. Here, when the above-mentioned addition value C is 4 or more, there are three ways in Fig. 5 ((f), (hL (i)
), but all input values are A.

One of B is "3" (state of rcJ in Figure 3),
and the other is “1” or “3” (rB in Figure 3)
J or "C" state).

On the other hand, the first. The comparison circuit 1 compares the second luminance data II and I2.
Compare with each other in 1e. Based on this comparison result, the circuit 13 selects height data I11 or I(2) corresponding to the larger (brighter) luminance data 11 or I2.
Height data H2 or H corresponding to the smaller (nlf) brightness data ■2 or I1 selected with a.
1 is selected by the selection circuit 13b. Then, based on the comparison result of the comparison circuit 11f, the selection circuits 13a, 1
The selection circuit 13c selects either the larger or smaller luminance data obtained in step 3b. That is, as shown in FIG. 5, (i) addition circuit 12
When the added value of is "4" or more (1st 17 = 5 Figures (f), Ih), (i)), the height data corresponding to the smaller luminance data is selected, while ( ii) When the above added value is smaller than "4" (Fig. 5) (al~(++l, (gI>), the height data corresponding to the larger luminance data is selected. In this way, The above-mentioned compositing process is specifically executed,
The finally selected height data becomes the composite height data Ho.

According to the above-mentioned synthesis process, one line sensor detects strong reflected light that is above its saturation level, and the other line sensor detects appropriate reflected light that is above the noise rail or detects a strong reflected light that is above the saturation level. When strong reflected light is detected (Fig. 5 (f1, (hl or turn (1)),
By selecting a smaller level closer to the JIJ level, more appropriate composite height data is obtained.

Also, when one line sensor detects reflected light that is stronger than the saturation rail, and the other line sensor detects reflected light that is weaker than the noise rail (see Figure 5),
c), (IT)), or when proper or weak foul light is detected by both line sensors below their saturation level (Fig. 5, 18), Tb), (d1,
In (e)), more appropriate composite height data can be obtained by selecting a larger level that is closer to the appropriate level. From these facts, it is possible not only to eliminate the influence of shadows as shown in Figure 6, but also to reduce the amount of reflected light detected by the two line sensors (
For example, even if the light is strongly reflected from an edge as shown in Figure 7), the more appropriate height data will be selected as the composite height data, and therefore, what kind of reflectance will it have? Accurate detection of parts is also possible.

From now on, the appropriate composite height data Ho obtained by the composite circuit will be used.
By sequentially capturing the images as the printed board P moves, three-dimensional shape data is obtained by a known means, and the mounting state of the component Q is inspected based on this shape data.

Note that the light irradiation means in the present invention is not limited to the configuration consisting of the semiconductor laser 1 and the cylindrical lens 2 shown in FIG. Any configuration may be used. However, if a semiconductor laser is used as a light source, the entire device can be made smaller.

Also, two line sensors 8. used as the light detection means.
9 may have a configuration in which some photoelectric conversion elements are arranged in a line, but in order to achieve high detection accuracy and high speed, it is desirable to use a CCD line sensor.

Further, the synthesis circuit shown in FIG. 4 is only one example of the synthesis means according to the present invention, and the present invention is not limited thereto.

Furthermore, although the above embodiment shows the case where a printed board P is used as the object to be inspected, the present invention can be applied to any object on which electronic components are mounted, such as a hybrid IC. applicable.

〔Effect of the invention〕

According to the mounted component inspection device of the present invention, not only can the influence of shadows be eliminated by detecting in two directions, but also it is possible to detect any type of component, including components with metal parts with high reflectance, black components with low reflectance, etc. Appropriate composite height data can be obtained even from parts with a low reflectance, thus enabling accurate part detection.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an optical system according to an embodiment of the present invention, and 2rgJ(0) and (b) are examples of light section images obtained by the line sensor 8.9 in FIG. 1, respectively. , a diagram showing an example of the luminance distribution in the y direction at an arbitrary position x1, and FIG. 3 shows the luminance level and the first . A diagram for explaining the relationship with the second reference level, FIG. 4 is a circuit diagram showing the synthesis circuit according to the above embodiment, and FIG. 5 explains the processing of the addition circuit 12 and selection circuit 13G in the synthesis circuit. Figure 6 shows the problem with conventional one-way detection (existence of parts that cannot be detected due to shadows), and Figure 7 shows the problem with conventional two-way detection (strong reflected light from the edge of the part). ). DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Cylindrical lens, 6.7... Oscillating mirror, 8.9... Line sensor, 112-llf... Comparison circuit, 12... Addition circuit, 132- 13C...Selection circuit.

Claims (1)

[Scope of Claims] 1) Light irradiation means (1, 2, 3) that vertically irradiates and scans a slit-shaped light beam (l_2) on an object to be inspected on which components are mounted; The reflected light (l_3, l_4) obtained from the object to be inspected by irradiation is reflected from two directions symmetrical with respect to the beam plane of the light beam by vibrating mirrors (6, 7).
For each of the two types of light-cutting images obtained from the two directions, a light detection means (4 to 9) detects each as a two-dimensional light-cutting image with two line sensors (8, 9) through the two line sensors (8, 9). and a peak detection means for detecting height data and brightness data of brightness peaks existing along the height direction, and three-dimensional shape data obtained by capturing the height data and brightness data along with the scanning. In the mounted component inspection apparatus that inspects the mounting state of the component on the object to be inspected based on the first and second luminance data (I_1, I_2
), a first reference level (SL1) corresponding to the noise level and a second reference level (SL2) corresponding to the saturation level of the line sensor are set. When one of the two luminance data is equal to or higher than the first reference level and the other is equal to or higher than the second reference level, the luminance data corresponding to the smaller luminance data (I_1 or I_2) Data (
H_1 or H_2) and select the composite height data (H_1 or H_2).
_0), and at other times height data (H_
1 or H_2) and select the composite height data (H_0
), and obtains the shape data based on the combined height data obtained by the combining means. 2) The synthesizing means combines the first and second luminance data (I
first and second comparison means (11a, 11b, respectively) for comparing _1, I_2) with the second reference level (SL2);
) and the first and second luminance data (I_1, I_2)
third and fourth comparing means (11c, 11d), respectively, for comparing the first reference level (SL1) with the first reference level (SL1);
, a fifth comparison means for comparing the second luminance data with each other (
11e), the level of the first luminance data is encoded according to the comparison results of the first and third comparison means, and the level of the second luminance data is encoded according to the comparison results of the second and fourth comparison means.
encoding means for encoding the level of the luminance data of;
the first and second encoded by the encoding means;
an addition means (12) for adding together the luminance data of the above, a sixth comparison means (11f) for comparing the addition result of the addition means with a predetermined value, and a larger one based on the comparison result of the fifth comparison means. First and second selection means (1) respectively select the height data (H_1 or H_2) corresponding to the smaller luminance data (I_1 or I_2).
3a, 13b) and third selection means (13c) for selecting one of the selected values of the first and second selection means based on the comparison result of the sixth comparison means, The mounted component inspection apparatus according to claim 1, wherein the height data obtained by the third selection means is used as the composite height data (H_0). 3) The light irradiation means obtains the slit-shaped light beam (l_2) by passing the laser light output from the semiconductor laser (1) through a cylindrical lens (2). The mounted component inspection device according to item 1 or 2. 4) The scanning by the light irradiation means is performed by moving the object to be inspected in a direction perpendicular to the slit-shaped light beam. The mounted component inspection device according to any one of the above. 5) The mounted component inspection apparatus according to any one of claims 1 to 4, wherein the line sensor is a CCD line sensor.