JPS6326510A - Inspection device for packaging component - Google Patents

Abstract

PURPOSE:To accurately detect a part regardless of its reflection factor without any influence of blooming by not using the value of a blooming part as height data, but interpolating the value by its peripheral values. CONSTITUTION:A printed board P where a component is packaged is projected with a slit light beam from a light irradiating means (semiconductor laser 1, etc.). Then, a line sensor 7 detects a light cutting line L formed on the printed board P by the irradiation of the light beam successively in the height direction. Then, a peak detecting circuit detects the peak of the height-directional a light cutting image obtained by the detection of the line sensor 7 to obtain brightness data and height data at the peak. Then, a data interpolating circuit interpolates height data values corresponding to them with peripheral values of the height data when the brightness data value is larger than a blooming level. Then, the height data is converted into binary data according to whether or not the data is within a specific range, and a decision circuit compares the binarized data with normal data to decide the packaging state of the component.

Description

[Detailed Description of the Invention] [↑Already Required] The present invention is a mounted component inspection device that uses a light cutting method to inspect the mounting state of a mounted component, in which a line sensor detects strong reflected light from an object to be inspected. In order to eliminate the blooming effect caused by saturation and enable accurate component inspection, when the value of the brightness data at the brightness peak of the light section image is equal to or higher than the blooming level, the height data that is forgotten relative to it is The value is interpolated with surrounding values.

[Industrial application field]

The present invention relates to a mounted component inspection apparatus that automatically inspects the mounting state of electronic components (particularly chip components) mounted on a printed circuit board using the optical cutting LFR 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 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. In order to improve the reliability of printed circuit boards using chip components, automation of appearance and inspection is essential. Against this background, there has been a strong desire to automate the visual inspection of chip component mounting.

[Traditional technique]

Conventional mounted component inspection equipment using the optical cutting 1Jfr method irradiates a slit-shaped light beam (hereinafter referred to as slit beam) onto a printed circuit board from directly above, and the optical cutting line formed there is detected by a line sensor. Detect from diagonally above with , obtain the height data at the luminance peak in the height direction of the obtained light section image, binarize this height data to extract the part shape, and compare this with the standard Bakun. Inspections are conducted by:

[Problem that the invention seeks to solve]

Generally, on a printed board, the light reflectance varies depending on the type and material of the components. For example, copper electrodes have high reflectance (and black parts have low reflectance. The ratio is
There are about 1000.

However, the range of the amount of light that can be detected by the line sensor is limited, and for example, the usable range of a CCD line sensor is only about 1:100. Therefore, when such a line sensor is used, if the light intensity of the slit beam is large, the amount of reflected light from parts with high reflectivity (such as copper electrodes) exceeds the detection ability of the line sensor, resulting in blooming (blooming). (a phenomenon in which bright areas have a trail) occurs. And vice versa,
If the amount of light of the slit beam is reduced to such an extent that the blooming does not occur, the amount of light reflected from portions with low reflectance (for example, black components) becomes even smaller, and becomes buried in noise and cannot be detected. If blooming occurs in this way, or if the necessary reflected light from the parts cannot be obtained, the accurate part shape cannot be obtained when the height data is binarized, and therefore, when comparing with the normal pattern, This will cause an error.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a mounted component inspection apparatus that can eliminate the influence of blooming and accurately detect both high and low reflectance areas.

[Means for solving problems]

As a means for erasing the tail of blooming, the present invention provides height data corresponding to the luminance data when the value of the luminance data at the luminance peak of the light-cut image is equal to or higher than the blooming level (the lowest level at which blooming occurs). The present invention is characterized in that it includes data interpolation means for interpolating the value of by using surrounding values.

[For production]

The above blooming level is a constant value for each line sensor, so if the brightness data value is above this level,
The height data at this time is affected by blooming. Therefore, by interpolating this value with surrounding values without using the value of this blooming portion as height data, it is possible to eliminate the blooming tail from the obtained height data. By interpolating the height data in this way, it is possible to detect areas with high reflectance without the influence of blooming, and the light intensity of the slit beam can be maintained to a certain extent, so that reflections from areas with low reflectance can be detected. Light can also be scaled to a positive value without being buried in noise.

〔Example〕

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

FIG. 1 is a configuration diagram showing an optical system according to 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 a laser beam j21 outputted from a semiconductor laser 1 into parallel light 12 with a collimating lens 2, further converts it into a slit-shaped light beam (slit beam) β3 with a cylindrical lens 3, 13 is irradiated from directly above onto a printed board door 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. Ru.

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 COD line sensor, etc.) 7. This light detection means first guides the reflected light β4 obliquely upward from the light cutting line to the galvanomirror 6 via the imaging lens 5. Galvano mirror
6 is finely rotated back and forth (photographed) within two fixed angle ranges, so the reflected light 14 guided to the galvanometer mirror 6 is
It is shaken 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 β4 in the height direction,
By swinging the galvanometer mirror 6 once in one direction, the entire image of the light cutting line can be seen. The image obtained through this type of detection is called a ``light cut-off image.''

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

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

In order to properly obtain the above-mentioned light-cut images sequentially over the entire surface of +fflP, the stage 4, galvano mirror 6, and line sensor 7 are operated by the stage drive circuit 9 and galvano mirror 7, respectively, based on instructions from the signal processing circuit 8. Drive circuit 10, line sensor drive circuit 11
are driven in synchronization with each other.

Next, this embodiment is equipped with a peak detection circuit (not shown) as one of the image processing systems for the optically sectioned image. Figure 2 (
In the light section image shown in al., for each position in the X direction,
There is a maximum brightness point (peak) in the height direction (Z direction) as shown in the figure (bl).The peak detection circuit detects the peak and calculates the height data (Z address) at this peak. The height data and brightness data at the peak thus obtained correspond accurately to the height and brightness of the detection target surface.

Next, by moving stage 4, print slope P
By determining the above height data and brightness data for all light section images sequentially obtained for the entire surface of
Create a height image and a brightness image along the XY plane. Examples of these images are shown in Figure 3(a) and (bl), respectively.As is clear from the figure, areas with high light reflectance (
For example, blooming occurs due to saturation of the line sensor 7 at a position corresponding to a metal electric scratching part, etc., and leaves a trail.

Therefore, in this embodiment, a data interpolation circuit (not shown) is provided as a means for erasing the tail caused by the blooming. In this data interpolation circuit, first, a blooming level, which is the lowest level at which blooming occurs, is set in advance, and it is determined whether the value of each luminance data of the luminance image is equal to or higher than the blooming level.

For example, if the value of the luminance data in region B is equal to or higher than the blooming level as shown in FIG. 3(b) (that is, if there is a blooming tail in region B), In the image, areas A and C above and below area B
The value of the height data in area B is interpolated using the value obtained by adding together the values of height data in area B and dividing by 2 (i.e., the average value).Such calculation is performed by software. This can be done either by using , or by using hardware. In this way, by interpolating the height data for all areas where blooming has occurred, all blooming tails in the height image can be erased. be able to.

As a result, as shown in FIG. 3 (C1), a height image that accurately corresponds to the part shape can be obtained.

Note that the blooming tail that occurs in the luminance image can also be removed in the same manner as in the case of the height image.

Next, a binarization circuit (not shown) for accurately extracting the part shape from the height image obtained by the data interpolation circuit will be described. In this circuit, height data is binarized depending on whether the value of each height data in the height image is within a predetermined range. For example, when the height data is within the above-mentioned predetermined range, it is set as "component J (rlJ)", and otherwise, it is set as "substrate (background) J (rOJ)".

Note that the above-mentioned predetermined range is set, for example, as follows. First, an area including the part Q to be inspected is set as a window W for the height image as shown in FIG. 4 (al and tc in FIG. 3). Then, as shown in FIG. 4 [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 value hs obtained by adding, for example, 1/2 value h1 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 hS is set as the predetermined range.

With this setting, the parts and the board can be accurately distinguished without being affected by the warping of the board. Note that instead of the above value h1, the allowable height range of the component is set to the above board height h.
a, and the range may be set as the above-mentioned predetermined range.

Finally, a judgment circuit (not shown) compares the binarized pattern obtained as described above with a 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.).

According to this embodiment, since blooming is removed by the data interpolation circuit described above, an accurate component shape can be obtained by the binarization circuit, and therefore no error occurs when comparing with a normal pattern, making it possible to accurately determine defects. become.

In this embodiment, the above-described image processing is performed based on instructions from the CPL 113 using the memory 12 shown in FIG.

〔Effect of the invention〕

According to the present invention, even parts with high reflectance on a printed board can be detected without the appearance of blooming, and this allows the light of the slit beam to be maintained to a certain extent, so even parts with low reflectance can be detected. It is possible to accurately detect parts without being buried in noise. Therefore, highly accurate inspection with very few errors is possible.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a configuration diagram showing an optical system according to an embodiment of the present invention, Fig. 2(a) and (bl are examples of light section images obtained in the same embodiment, respectively); A diagram showing an example of the luminance distribution in the Z direction at the arbitrary position 4A and 4B are diagrams showing a window and histogram processing for setting a height range when binarizing a height image in the same embodiment, respectively. 1... Semiconductor laser, 2... Collimating lens, 3... Cylindrical lens, 6... Galvano mirror 1 7... Line sensor. Patent applicant Fujitsu Ltd. One talented person who scolds the bow ＼Figure 1

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).
), a 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; data interpolation means for interpolating the corresponding height data value with surrounding values of the height data when the value of the brightness data is equal to or higher than the blooming level; and height data obtained through the data interpolation means. A binarization means that binarizes the height data based on whether or not it is within a predetermined range, and a binarization means that compares the binarized data obtained by the binarization means with standard normal data, and uses the comparison result to A mounted component inspection apparatus characterized by comprising: determination means for determining the mounting state of the component based on the mounting state of the component. 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 data interpolation means interpolates the height data value when the luminance data value is equal to or higher than the blooming level using an average value of data above and below the height data. The mounted component inspection device according to any one of Items 1 to 3. 5) The mounted component inspection apparatus according to any one of claims 1 to 4, wherein the data interpolation means interpolates the luminance data as well as the height data. 6) The mounted component inspection apparatus according to any one of claims 1 to 5, wherein the line sensor is a CCD line sensor.