JPS63128242A - Inspecting device for mounted parts - Google Patents

Abstract

PURPOSE:To improve instrumentation resolution by correcting two kinds of height data and luminance data based on an optical cut image obtained from two directions, based on a height histogram, and also, synthesizing the height data, based on magnitude of the luminance data. CONSTITUTION:Laser light l1 from a semiconductor laser 1 is converted to a slit-shaped light beam l2 by a cylindrical lens 2 and radiated onto a printed board P, and an optical cutting line L is formed on a substrate R and parts Q. The cutting line L is detected by line sensors 8, 9 through vibration mirrors 6, 7, etc., from two symmetrical directions of the beam l2, and two kinds of optical cut images obtained by the sensors 8, 9 are fetched as height data and luminance data by a sequential peak detecting circuit which is not shown in the figure. In these shape data, there is a height shift due to a difference of the measured height by the sensors 8, 9, therefore, a shift of the height data is corrected, based on a height histogram, and two kinds of height data which have been corrected are synthesized, based on the luminance data. By executing an inspection, based on this synthesized data, the instrumentation resolution is improved, and an influence by irregular noise is decreased.

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 photosection method, which uses two types of high-resolution images based on photosection images obtained from two directions. For the height data and brightness data, the mutual deviation of the height data is corrected based on the height histogram, and the two types of corrected height data are added to each other based on the size of the brightness data, or one of them is By doubling the data and performing inspection based on this combined data, we can eliminate the influence of shadows, increase measurement resolution, and reduce the influence of irregularity noise. This makes it possible to eliminate the influence of height deviation between images from two directions.

[Industrial Application Field] The present invention relates to a mounted component inspection device that automatically inspects electronic components (particularly chip 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.

[Traditional techniques]

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 component, and the mounting state is determined by comparing this with a standard pattern. There is a known method that performs the following tests.

However, when measuring the three-dimensional shape of a component from one direction as described above, there are places 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 combining the two types of data regarding height and brightness obtained from this, the undetectable area due to the shadows mentioned above can be eliminated. A device has been proposed that eliminates the 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 not affected by shadows) is selected from the two types of data, and the data is converted into one type of data.

[Problem that the invention seeks to solve]

The conventional device described above that detects from two directions only selects the one with higher brightness from among the two types of data to obtain composite data, so it is difficult to detect data from two directions while using two line sensors. However, the resolution was the same as when using one line sensor. Moreover, if irregular noise with high brightness occurs in one of the above two types of data, this noise will be incorporated into the above composite data as it is, resulting in the problem that the influence of the above noise will be significant. There was also.

Furthermore, if the heights measured by the two line sensors are offset from the surface to be inspected, the images that are offset from each other will be combined, resulting in an inappropriate shape of the combined image. There was also.

In view of the above problems, the present invention makes it possible to eliminate the influence of shadows, improve measurement resolution, reduce the influence of irregularity noise, and moreover, correctly synthesize images even if images from two directions are shifted. The purpose is to provide a mounted component inspection device that can perform the following tasks.

[Means for solving problems]

The present invention detects two types of light cut images from two directions using two line sensors, obtains two types of height data and brightness data based on this, and uses these data. The present invention is a mounted component inspection apparatus which obtains three-dimensional shape data using the following correction means and synthesis means as described below.

The correction means creates a height histogram within a limited area including the component for each of the two types of height data, and corrects the deviation between the two types of height data based on the position of the frequency peak. It is a means to do so.

The synthesizing means adds the two types of height data corrected by the correcting means to obtain synthetic height data when both of the two types of luminance data have a value equal to or higher than a predetermined specific value; When the value of at least one of the two types of luminance data is smaller than the specific value, the corrected height data corresponding to the larger luminance data is doubled to obtain composite height data. It is also a means for obtaining composite luminance data based on the two types of luminance data. The three-dimensional shape data described above is obtained based on the composite height data and composite luminance data obtained in this manner.

[For production]

Since the correction means corrects the deviation between the two types of height data, the synthesis means synthesizes the height data with no deviation from each other.

Therefore, even if the two types of height data are different from each other, a composite image with the correct shape can be obtained.

In addition, in the above synthesis means, the combined height data is obtained by adding two types of height data to each other (or doubling only one of them) based on the magnitude of the luminance data, so the measurement resolution is improved. , that is, it is smaller than the conventional value of 2. At the same time, even if high-intensity irregular noise occurs in one of the two types of data, it will be added to the other to create composite data, so overall, the influence of noise will be reduced compared to the conventional 2 types of data. becomes smaller.

Of course, since the two line sensors detect from two directions, the influence of shadows is also eliminated.

〔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, a laser beam 11 output from a semiconductor laser 1 is passed through a cylindrical lens 2 into a slit-shaped light beam I! Converted to 2. This light beam 12 is vertically irradiated onto a printed board door placed on a stage 3 moving in the direction of arrow A.

That is, the printed board P is scanned by the light beam I22 in the direction indicated by the arrow. 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 12.

The light cutting line is detected by two line sensors 8.9 from two symmetrical directions with respect to the beam plane of the light beam 12 via an imaging lens 4.5 and a vibrating mirror 6.7. . 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 light β3.14 from the light cutting vAL changes to the line sensor due to the vibration. It moves back and forth on the light receiving surface of 8.9. Therefore, the line sensor 8.9 is the vibrating mirror 6.
．． With one swing of 7 in one direction, the entire image of the light cutting line,
In other words, a two-dimensional light section image can be detected at high speed.

The above-mentioned photocutting image is, for example, as shown in FIG.
The light cutting line is obtained as a substantially band-shaped image with a shift according to the height of the object (component Q, substrate R) on which the line is formed, and these are multilevel images with brightness according to the reflectance of the object. It is a tone-toned image. The stage 3, the vibrating mirror 6.7, and the line sensor 8.9 are properly synchronized with each other, so that two types of light-cut images can be sequentially obtained over the entire surface of the printed board P. Two types of light cut images obtained from the line sensor 8.9 are sequentially sent to a peak detection circuit (not shown). In the light section image shown in FIG. 2(a), a brightness peak K as shown in FIG. 2(a) 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.

By sequentially importing these two types of height data (Hl, H2) and brightness data (11, I2), two types of three-dimensional shape data will be obtained corresponding to the detection direction. . However, as described above, these shape data may have height deviations from each other due to, for example, differences in the measured heights by the line sensors 8.9. Therefore, in this embodiment, a correction circuit is provided next to the peak detection circuit as a means for correcting this height deviation. This correction circuit consists of a deviation amount detection section and a subtraction section, which will be described below.

In the deviation amount detection unit, for each of the two types of height data obtained by the peak detection circuit, the deviation amount detection unit calculates the height data as shown in FIG. 3 (al, (
Cut out a limited area M including arbitrary parts like bl,
A height histogram is created for each of the height data (Fig. 3, tc+, (d)). Looking at this height histogram, the substrate height can be determined from the position of the frequency peak. If the height measured by the line sensor 8.9 is different, the substrate height obtained from the two height histograms will also be different.

Therefore, using the substrate height of the height histogram corresponding to the line sensor 9 as a reference, the height deviation measured up to the substrate height of the height histogram corresponding to the line sensor 8 is detected,
This height deviation amount is sent to the subtraction unit 10 at the next stage (Fig. 3(e)
)).

The subtraction unit 10 is equipped with one subtraction circuit 11 as shown in FIG. Height data H, (height data corresponding to the line sensor 8, which is not used as a reference when detecting the amount of height deviation) is input. The subtraction circuit 11 subtracts the height deviation amount from the height data H1 and outputs the subtracted value as new height data H1'.

The height data H8' obtained in this way corresponds to the other height data H2 corresponding to the line sensor 9 (that is, the one used as a reference when detecting the height deviation amount). The height difference is gone. In other words, the height deviation between the two types of height data H+ obtained by the peak detection circuit and Hz is corrected, and the height data H+ with no deviation from each other is created.
', H2 is obtained.

Next, a synthesis circuit 20 is a means for synthesizing the above-mentioned two types of height data H1'', H2, luminance data ■., and 1g with each other to create composite height data H0 and composite luminance data ■. I will explain about it.

As shown in FIG. 4, the synthesis circuit 20 includes three comparison circuits 21a, 21b, 21c, one addition circuit 22, two multiplication circuits 23a, 23b, and three selection circuits 24a, 24.
b, 24C1 and one AND circuit 25. Comparing circuits 21a to 21C are circuits that compare input A and input B, and set output C to "1" if A2B, and set output C to "0" if A<B. The adder circuit 22 adds input A and input B to each other, and obtains this added value (A+B
) is the output C. Multiplication circuits 23a, 23b
is a circuit that doubles the input A and outputs the multiplied value (AX2) as the output B. The selection circuits 24a to 24c select the input A to output C if the input S is "1", and the selection circuits 24a to 24c select the input A as the output C if the input S is "1".
0'', the circuit selects input B and outputs C.

The synthesis circuit 20 receives the above-mentioned corrected height data H+'
, H2, brightness data I+, Iz, and minimum brightness (a predetermined specific value, the lowest brightness level necessary to distinguish the shaded area) IMIN are input.

In the synthesis circuit 20, when the luminance data (1) and (2) are both equal to or higher than the minimum luminance (1N), the comparison circuits 21a, 21
Since "1" is output from b, AND circuit 2
The output of 5 is also "1". Then, since the input S of the selection circuit 24b becomes "1", the output value of the addition circuit 22, that is, the sum of the height data Hr' and H2 is selected, and this is output as the composite height data H0.

On the other hand, when the value of at least one of the brightness data II and I2 is smaller than the minimum brightness INIM, the comparison circuit 21a,
Since "0" is output from at least one of 21b,
The output of the AND circuit 25 also becomes "0", and the selection circuit 24b
Then, the output value of the other selection circuit 24a is selected.

At this time, brightness data 1. If the value of the luminance data is 17 or more, the output of the comparator circuit 2IC becomes "1", so the value obtained by doubling the height data HI' by the multiplier circuit 23a becomes the output value of the selection circuit 24a, and on the other hand, If the value of the luminance data 2 is larger than the luminance data I, the output of the Hisaki circuit 21c becomes "0", so the height data H2 is added to the multiplication circuit 23.
The value doubled by b becomes the output value of the selection circuit 24a. In other words, the value obtained by doubling the height data H+' or H2 corresponding to the larger luminance data 11 or ■2 is
It is output as composite height data H0.

Also, composite brightness data■. Finally, the brightness data It,
The comparison circuit 21C compares the magnitude of Tz, and the selection circuit 24C selects the larger luminance data 1 or I2.

Therefore, in areas without shadows, there are two types of height data H3',
The value obtained by adding H2 becomes the composite height Ho, and in the shaded area, the value obtained by doubling the height data of the non-shaded side (the one with greater brightness) becomes the composite height data H6, so the composite height data H8
Not only is there no influence from shadows, but the measurement resolution is improved, as shown in Figure 5 fQl, (f) compared to the conventional example (which simply selects the height data with greater brightness). The resolution becomes smaller than 2. Also, for example, the fifth
As shown in Figures (al, (b)), high-intensity irregular noise occurs in one of the two types of light section images obtained from the line sensor 8.9, and the peak detection circuit (C1,
Even if the position of the above noise is detected as height data as in (d), the combined height data H6 obtained by adding the other height data that is not affected by the noise. In this case, the influence of the noise is reduced, that is, the influence of noise is reduced to 2 compared to the conventional example, as shown in FIGS.

Thereafter, by sequentially importing these composite height data H8 and composite luminance data Io as the printed board P moves, three-dimensional shape data is obtained by known means, and the component Q is determined based on this shape data. Check the implementation status.

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.

In addition, the two line sensors used in the light detection means are:
Although any configuration in which some photoelectric conversion elements are arranged in a line may be used, it is preferable to use a CCD line sensor in order to achieve high detection accuracy and high speed.

Furthermore, the correction means is not limited to the correction circuit described in the above embodiment, but may be any device that can correct the deviation between two types of height data based on the frequency peak position of the height histogram. , it can be anything. Similarly, the composition means is not limited to the configuration of the above embodiment.

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 the measurement resolution can be improved (conventional resolution of 2) and the influence of irregularity noise can be reduced by means of synthesis. (reduced to 2 compared to the conventional method), and even if images from two directions have a height deviation from each other, it is possible to obtain an appropriate image without the influence of the deviation by the correction means.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an optical system according to an embodiment of the present invention, and FIG. , a diagram showing an example of the luminance distribution in the y direction at the arbitrary position x1, FIG. A circuit diagram showing a part of the correction circuit (subtraction unit) and a synthesis circuit according to the above embodiment, Fig. 5+al~(fl is a diagram for explaining the main effects of the above embodiment, Fig. 6 is a diagram showing the conventional It is a diagram showing a problem in one-way detection (existence of undetectable portion due to shadow). ■... Semiconductor laser, 2... Cylindrical lens, 6.7... Oscillating mirror, =22-8.9 ... line sensor, 10 ... subtraction unit (part of correction circuit), 11 ... subtraction circuit, 20 ... synthesis circuit, 21a, 21b, 21c -- comparison circuit, 22 ... addition Circuit, 23a, 23b...=multiplication circuit, 24a, 24b, 24c...-selection circuit, 25...AND circuit, p2...Slit-shaped light beam, β3.14...Reflected light, H+, HI', H2...Height data, 1+, 12
... Brightness data, I, 41N ... Minimum brightness, Ho ... Composite height data, ■. ...Synthetic luminance data, M...Limited area.

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
For each of the types of height data (H_1, H_2), a height histogram is created within the limited area (M) including the part, and the distance between the two types of height data is calculated based on the frequency peak position of the height histogram. and two types of luminance data (I_1, I
_2) both have a value equal to or greater than a predetermined specific value (I_M_I_N), the two types of height data (H
_1', H_2) to create composite height data (H_0)
On the other hand, the two types of luminance data (I_1, I_2
) is the specific value (I_M_I_N
), the corrected height data corresponding to the larger luminance data is doubled to obtain composite height data (H_0), and composite luminance data (I_0) is calculated based on the two types of luminance data. ) for obtaining the shape data based on the composite height data and the composite luminance data obtained by the composite means. 2) The synthesizing means combines the two types of luminance data (I_1
, I_2) as the specific value (I_M_I_
first and second comparing means (21a, 21b)
), a third comparing means (21c) for comparing the values of the two types of luminance data with each other, and an adding means (22) for adding together the two types of height data (H_1', H_2) after the correction. and first and second multiplication means (23a, 23b) that double the two types of height data after the correction, respectively, and the first and second multiplication means (23a, 23b) that double the two types of height data after the correction, and the first and second a first selection means (24a) for selecting one of the multiplied values by the multiplication means; and a first selection means (24a) for selecting one of the multiplied values by the multiplication means; a second selection means (24a) for selecting one of the multiplication values selected by the first selection means (24a);
2. The mounted component inspection apparatus according to claim 1, further comprising: b), wherein the value obtained by the second selection means is used as the composite height data (H_0). 3) The synthesizing means combines the two types of luminance data (I_1
, I_2), and a selection means (24c) for selecting the larger luminance data determined by the comparing means from among the two types of luminance data. 3. The mounted component inspection apparatus according to claim 1, wherein the luminance data obtained by the selection means is used as the composite luminance data (I_0). 4) The correction means includes a deviation amount detection means for detecting a mutual deviation amount of frequency peak positions of the height histograms obtained corresponding to the two directions, using one of the frequency peak positions as a reference; Subtraction means (11) for subtracting the amount of deviation from the height data (H_1) that is not used as the reference among the two types of height data (H_1, H_2);
Claim 1, characterized in that the subtracted value (H_1') by the subtracting means and the reference height data (H_2) are used as the corrected height data. The mounted component inspection device according to any one of items 1 to 3. 5) Claims characterized in that 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 any one of Items 1 to 4. 6) 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. 7) The mounted component inspection apparatus according to any one of claims 1 to 6, wherein the line sensor is a CCD line sensor.