JPS6326508A - Inspection device for packaging component - Google Patents

Abstract

PURPOSE:To obtain the correct shape of component which is not affected by a shadow regardless of the kind of the component by converting height data at the brightness peak of a light cutting image into a binarization data. CONSTITUTION:Laser light l1 from a semiconductor laser 1 is converted by a collimator lens 2 into parallel light l2, which is further converted by a cylindrical lens 3 into a slit beam l3. Then, a printed circuit board P is irradiated with the beam l3 from right above. Various components Q are mounted on the printed circuit board P and a light cutting line L is formed on a substrate R and the components Q by the irradiation of the beam l3. Then, upward slanting reflected light l4 from the light cutting line L is guided to a galvanomirror 6 and deflected up and down according to the vibration of the mirror 6. Then a line sensor 7 detects the deflected light l4 successively and the whole image of the light cutting line L can be seen by one swing of the mirror 6 in one direction, thereby obtaining the correct shape of component which is not affected by a shadow.

Description

[Detailed Description of the Invention] [4 Summary] The present invention provides a method for binarizing height data at the brightness peak of a light section image in a mounted component inspection device that inspects the mounting state of a mounted component using a light section method. By doing so, when extracting the part shape, the above 2.
By performing value conversion, it is possible to extract the correct part shape that is not affected by shadows, regardless of the type of part.

[Industrial Field of Application] The present invention relates to a mounted component inspection apparatus G that automatically inspects the mounting state of electronic components (particularly chip portions) mounted on a printing board using an optical cutting method.

In recent years, surface-mounted components (chip components) have come into widespread use in order to miniaturize electronic devices. In the manufacturing process of printed circuit boards using 6-chip and 7-chip parts, the number of which is expected to rapidly increase as the number of chip components increases, mounting is carried out 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 a slit-shaped light beam (hereinafter referred to as slit beam) onto a printed board from directly above, and a light cut 1 [M
The part shape is detected from diagonally above with a line sensor, the part shape is extracted from the obtained light-cut image, and inspection is performed by comparing this with a reference pattern.

One way to extract the shape of the part is to first find the peak of brightness in the height direction of the light-cut image, obtain height data at this peak, and then obtain the height data above a certain value. (or within a certain range), it is set as "part", and at other times, it is binarized as "background" to extract the two-part shape.

Another method is to set the height data and brightness data at the peak value to j8 in the same way as above, and then set the first and second brightness data to be above a fixed specific value, and the quotient data to be above a certain value ( or within a certain range) as a "part",
At other times, Riko's ``background'' is 2 (something that becomes direct).

[Problem that the invention seeks to solve]

Generally, in a mounted component inspection device using the optical cutting method, the sixth
As shown in the figure, when a slit beam p is irradiated onto a substrate R near a component Q, the slit beam 2 becomes a floor of the component Q for the line sensor LS, and cannot be detected.

Therefore, when the former method described above is used to extract the part shape, when the peak value of brightness is determined and the height data is obtained as described above, in the shaded part, the However, due to the influence of diffused light, etc., the height of the peak varies randomly, and only an incorrect height of 6'ω can be obtained. Therefore, if height data is simply binarized using a certain height as a reference, there is a drawback that only an inaccurate part shape can be obtained in the shaded areas.

In addition, devices that use the latter method to extract the part shape take into consideration the color, in which the luminance in the shaded area is smaller than the shaded area, and a fixed area with luminance data is taken into consideration. When it is smaller than .about..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times..times.. However, in general, parts are either black or white depending on their type, and their light reflectances vary greatly. Therefore, the optimal value of the brightness level required to remove the shaded part as an undetectable part (hereinafter referred to as the "required brightness level") differs depending on the type of component. Therefore,
If the required brightness level is fixed as described above, for example, if the required brightness level is too high for a black part, the part itself will be detected as missing, and the required brightness level for a white part will be too high. If the level is too small, there is a problem in that even shadow parts are treated as parts.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a mounted component inspection apparatus that can obtain a correct component shape regardless of the type of component.

[Means for solving problems]

As a means for extracting the shape of a part, the present invention detects the brightness peak in the height direction of a light section image obtained by sequentially detecting a slit beam with a line sensor, and obtains the brightness data and height data. The detection means and the above luminance data are predetermined in accordance with the type of parts.
The present invention is characterized by comprising a binarization means for binarizing the height data depending on whether the volatility level is higher than the level and the height data is within a predetermined range.

[For production]

As mentioned above, if the optimal required brightness level corresponding to the type of component is set in advance, the optimal required brightness level can be used when comparing with the brightness data obtained by the peak detection means. can. Therefore, regardless of the type of part, it is possible to extract a correct part shape that is not affected by shadows.

〔Example〕

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

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

In the figure, the present embodiment first includes a light irradiation means consisting of a semiconductor laser 1, a collimating lens 2, and a cylindrical lens 3. This light irradiation means converts laser light 11 output from a semiconductor laser 1 into parallel light 12 with a collimating lens 2, and further converts the laser light 11 outputted from a semiconductor laser 1 into parallel light 12 with a cylindrical lens 3.
is converted into a slit-shaped light beam (slit beam) 13, and this slit beam β is irradiated from directly above onto a printed board P placed on a stage 4 movable in the X and Y directions. The printed board P has various components (particularly chip components) Q mounted on the substrate R, and a light cutting line is formed on the substrate R and the components Q by the irradiation of the slit beam 13. ing.

Furthermore, it is provided with a light detection means consisting of an imaging lens 5, a galvanometer mirror 6, and a line sensor (for example, a CCD line sensor, etc.) 7. This light detection means first guides the diagonally upward reflected light 24 from the light cutting line to the galvano mirror 6 via the imaging lens 5 (the galvano mirror 6 is configured to Since it is finely reciprocated (vibrated), the reflected light 14 guided to the galvanometer mirror 6
is swung up and down along with the above vibration. A line sensor 7 sequentially detects this reflected light. Then, the line sensor 7 sequentially detects the reflected light 1.4 in the height direction, and by swinging the galvanometer mirror 6 once in one direction, the entire image of the light cutting line B can be seen. Hereinafter, this image will be referred to as a "light-section image."

As shown in FIG. 2, this light-cutting image is a substantially slit-shaped image (m, , m2 .m3), and these become multi-gradation gradation images corresponding to the luminance of the object. In the figure, images m, , m
2 and m3 correspond to the high component, low component, and board, respectively.

Such a light cut image can be expressed by an X address and an X address, where the X address corresponds to the line direction of the line sensor 7, and the X address corresponds to the height.

In addition, in order to properly obtain the above-mentioned light cut images on the entire surface of the printed board P, the stage 4, the galvano mirror 6,
The line sensor 7 is operated by a stage drive circuit 9, a galvano mirror drive circuit 10, and a line sensor drive circuit 11, respectively, based on instructions from a signal processing circuit 8.
They are driven in synchronization with each other.

Next, this embodiment includes a peak detection circuit (not shown) as one of the image processing systems for the optically sectioned image. In the light section image shown in FIG. 2, the highest brightness point (peak) in the height direction (Z direction) exists for each position in the X direction. The peak detection circuit detects the peak and obtains height data (Z address) and brightness data (for example, 8-bit gradation data) at this peak. The height data and brightness data at the peak obtained in this manner accurately correspond to the height and brightness of the detection target surface, except for the shaded portions described above.

The peak detection circuit further creates a height image and a brightness image along the XY plane by determining the height data and brightness data for all the light cut images sequentially grooved on the entire surface of the printed board P. An example of each of these images is shown in FIG. 3(a).

(shown in bl. In the same figure (al, images m+, , m, □
corresponds to the part, and in the Y direction there is an image (hatched area) corresponding to the shaded part of the part. In the same figure (11), the images ml, , m, g correspond to the component body, and the images ml,
,.

m1□, corresponds to the component electrode, and the image m21. mz□, m
z3゜mz4 corresponds to the substrate electrode, and as in the same figure (al), an image (shaded area) corresponding to the shaded part of the component is created in the Y direction.The height image and brightness image are , all of them have multiple gradations.In order to make it easier to understand these images, the brightness and height obtained by sequentially detecting the object in the Y direction as shown in Figure 4(a) are shown below. Changes in the height are shown in FIGS.

Then, in the shaded part B, the brightness level becomes lower than other parts as shown in the same figure (bl), and furthermore, in the same figure (C)
As is clear from the figure, the height appears randomly due to the influence of diffused light. The hatched areas shown in FIG. 3(a) and (bl) also show similar changes.

Therefore, next, we will use a binarization circuit (not shown) to accurately extract the part shape without being affected by shadows from the height image.
I will explain about it. In this circuit, the height image is binarized based on whether the values of each pixel of the luminance image and the height image satisfy the following two conditions.

The first condition is that the value of the brightness image (pixel) is equal to or higher than the required brightness level. Note that this required brightness level is the brightness level necessary to distinguish and remove the shaded part from other parts, and is set to the optimal value according to the type of part, and is preset in the system memory ( Memory 12) in Figure 1
The parts are stored in and taken out depending on the type of parts. A specific value is set, for example, to a level lower than the brightness level of FIG. 4 (portion A of the component body, as shown in bl) and higher than the brightness level of the shadow (portion B). In this way, the required luminance level will generally be a small value for black parts and a large value for white parts.

The second condition is that the value of the height image (pixel) is within a predetermined range. This range is set, for example, as follows. First, as shown in FIG. 5+a), an area including the part Q to be inspected is set as a window W in the height image. Then, as shown in FIG. 5(b), a histogram of heights within the window W is created.

Pay attention to this histogram in order from the lowest height to the highest height, find the height at which the frequency has a peak at a predetermined specific value a or more, and set this height ho as the substrate height. Next, a height h5 obtained by adding, for example, 1/2 of the general height of the component to the substrate height ho is set as a height slice level, and a range equal to or higher than this slice level h8 is set as the predetermined range.

With this setting, the parts and the board can be accurately distinguished without being affected by the warpage of the board. In addition, instead of the above value, the allowable height range of the component is expressed as the above board height ho.
, and the range may be set as the above-mentioned predetermined range.

In the binarization circuit, the above-mentioned 1. The height image is binarized as a "component" when both of the second conditions are satisfied, and as a "substrate (background)" otherwise. Due to this,
For example, since the shaded area (shaded area) is removed from the height image shown in FIG. 3(a), it is possible to extract the correct part shape that is not affected by the shade. To explain this with reference to Fig. 4, the luminance shown in Fig. 4Cb) is lower than the required luminance level in the shaded area, so the corresponding part in Fig. 4C is removed as the background. A binarized pattern having an accurate component shape as shown in FIG. 2(d) can be obtained. In other words, the required luminance level is too high and the main body of the component is chipped and removed, and the required luminance level is too low and the shaded part is not extracted as a component.

Finally, a judgment circuit (not shown) compares the binarized pattern obtained as described above with the standard normal pattern, and determines the mounting state of the component (for example, the " Determine whether there are defects such as "missing", "misalignment", "defective height", etc.).

As described above, according to this embodiment, a correct part shape that is not affected by shadows can be obtained regardless of the type of part.

In this embodiment, the above-described image processing is performed based on instructions from the CPU 13 shown in FIG.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an accurate part shape that is not affected by shadows, regardless of the type of the part, and therefore it is possible to significantly improve inspection performance (defect detection rate).

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing an example of a light section image obtained by the same embodiment, and Fig. 3 is a diagram showing an example of a light section image obtained by the same embodiment. Figure 4 Ta) to Figure 4 (d) are reference diagrams for explaining the effects of the same example, and Figures 5 (a) and (b) are diagrams showing examples of brightness images and brightness images, respectively. FIG. 6 is a diagram showing a window and histogram processing for setting a height range when binarizing a height image, and FIG. 6 is a diagram showing undetectable areas due to shadows. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Collimating lens, 3... Cylindrical lens, 6... Galvano mirror-1 7... Line sensor. Patent Applicant: Fujitsu Ltd. Configuration of an Embodiment of the Invention 1st Figure Fumi Dotto vt'l'+% Ibuki's first row 2nd ref (b) Rain & Statue and υ degree wii Ichita・'' Figure 3 ■4 Figure Wind Tsu (o) Himatatgerumsho (b) Height Mountain Ifuno 2su/Iz Haku 5 Figure

Claims (1)

[Scope of Claims] 1) Light irradiation means (1, 2, 3) for irradiating a slit-shaped light beam onto a printed circuit board on which components are mounted; A light detection means (5, 6, 7) sequentially detects the light cutting line formed on the board in the height direction using a line sensor (7).
); peak detection means for detecting a peak in brightness in the height direction of the light-cut image obtained by the detection by the light detection means, and obtaining brightness data and height data at the peak; and the brightness data indicates the type of part. binarization means for binarizing the height data depending on whether or not the luminance is equal to or higher than an optimum necessary brightness level predetermined corresponding to the above, and whether or not the height data is within a predetermined range. and a determination means for comparing the binarized data obtained by the binarization means with reference normal data and determining the mounting state of the component based on the comparison result. Parts inspection equipment. 2) The light irradiation means includes a semiconductor laser (1) that outputs a laser beam, a collimating lens (2) that converts the laser beam obtained by the semiconductor laser into parallel light, and a collimating lens (2) that converts the laser beam obtained by the semiconductor laser into parallel light. The mounted component inspection apparatus according to claim 1, further comprising a cylindrical lens (3) that converts light into the slit-shaped light beam. 3) The light detection means is characterized in that the reflected light from the light cutting line is swung in the height direction by a galvanometer mirror (6), and the swayed reflected light is sequentially detected by the line sensor (7). A mounted component inspection device according to claim 1 or 2. 4) The binarization means binarizes it as a "component" when the luminance data is equal to or higher than the required luminance level and the height data is within the predetermined range, and otherwise binarizes it as a "background". A mounted component inspection device according to any one of claims 1 to 3, characterized in that: 5) The mounted component inspection apparatus according to any one of claims 1 to 4, wherein the line sensor is a CCD line sensor.