JPH01100409A - Apparatus for inspecting positional shift of chip component - Google Patents

Abstract

PURPOSE:To always stably inspect positional shift, by performing imaging so that the light cutting line projected on a substrate and a mounting chip component becomes horizontal in an image and analyzing the shape of the light cutting line in the image to detect the positional shift of the chip component. CONSTITUTION:A printed circuit board having a chip component being an object to be inspected mounted thereon is mounted on an XY stage 5 and two slit light projectors 3 are arranged so that the light cutting lines allowed to irradiate the printed circuit board cross each other at a right angle. Further, the galvano mirror 4 controlled by an image processing control apparatus 8 is provided in order to control the irradiation positions of the projected slit light beams by reflecting said light. Then, two light cutting lines allowed to irradiate the printed circuit board are imaged in the horizontal direction within an image by two television cameras 1 and a half mirror 2. The shapes of the light cutting lines in the image are analyzed by the image processing control apparatus 8 to detect the positional shift of the chip component.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic component mounting board inspection device, and particularly to a compact and compact electronic component mounting board inspection device.
The present invention relates to a chip component misalignment inspection device having a detection optical system suitable for automatic misalignment inspection after surface-mounted chip components are mounted on a printed circuit board.

[Conventional technology]

A conventional chip component misalignment inspection device for a printed circuit board on which chip components are mounted is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-294502.
As described in the issue, the target part is illuminated using multiple lights, an image with good contrast and an image that emphasizes only a specific target are input, and this input image is binarized to detect the positional deviation of the part. A method of testing was taken.

Furthermore, as described in JP-A No. 58-135941, a method of determining the external shape and position of a chip component by irradiating the target with parallel illumination to form a shadow of the target component on the substrate, and inputting the shadow as an image. was taking.

[Problem that the invention seeks to solve]

The method disclosed in Japanese Patent Application Laid-Open No. 61-294502 does not take into account the case where it is difficult to obtain contrast due to the combination of target component color and board color, and there are limitations on the objects that can be inspected.

Furthermore, the device disclosed in JP-A No. 58-155941 did not take into consideration parts with more complex shapes such as cylindrical parts and other irregularly shaped parts, and as mentioned above, there were limitations on the objects that could be inspected. .

Furthermore, although both of the above conventional technologies actively project light, problems such as pluming and smearing on the image sensor that occur especially when using a solid-state image sensor due to high-intensity reflected light from the solder surface etc. Due to lack of consideration, there was a problem in that soldering made later inspection difficult.

An object of the present invention is to provide a chip component misalignment inspection device that can always and stably inspect the misalignment of chip components after soldering to a printed circuit board without being affected by the color and shape of the chip components or the color of the printed circuit board. There is something to do.

[Means for solving problems]

The above purpose is to reflect the slit light from the slit light projector with a galvanometer mirror and then project it onto the board from an oblique direction to project a light cutting line onto the board and the mounted chip components.
This optical cutting line is imaged from above the board using a television camera so that the optical cutting line is horizontal in the image, and the shape of the optical cutting line in the image is analyzed by an image processing control device to detect the positional shift of the chip components. This is achieved by a chip component misalignment inspection device.

[Effect]

In the above-mentioned chip component misalignment inspection device, a slit light is irradiated onto the board from an oblique direction [By capturing the image from directly above, the position of the light cutting line in the image changes depending on the height of the irradiated surface. Therefore, by analyzing the shape of the optical cutting line, the height of the object can be determined.1 From this, the position of the chip component mounted on the board can be detected from the unevenness of the board surface, and the negative shape of the chip and the board is not affected by the color of At this time, by irradiating the target with the optical cutting line in a cross pattern, horizontal and vertical displacements of the target chip can be detected.

In addition, the galvanometer mirror can reflect the slit light projected from the slit light projector and irradiate the target with a light cutting line at any angle. Can irradiate cutting lines. Furthermore, by imaging the light cutting line irradiated on the target so that it is horizontal in the image, if the slit light or general irradiation directly hits the metal surface such as solder and returns high-intensity reflected light. In particular, bright vertical lines called smear or blooming, which occur when solid-state imaging devices are used, and light cutting lines can be distinguished as the direction of the bright line in the image.
Erroneous detection can be prevented when detecting photo-cleaved fat.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 10.

FIG. 1 is a schematic diagram showing an embodiment of a chip component positional deviation inspection device according to the present invention. In Fig. 1, 1 is a television camera that images the inspection object, and 2 is a half mirror that optically connects the two television cameras 1, so that the two television cameras 1 are able to capture the same location at angles shifted by 9 QO. It is possible to take images. 3 is a slit light projector (
4 is a mirror, such as a galvano mirror, for reflecting the slit light projected from the slit light projector 3 and controlling the irradiation position of the light cutting line on the substrate.
It is. Reference numeral 5 denotes an XY stage that holds a printed circuit board on which chip components to be inspected are mounted, and is driven by an xy table that is movable in a plane. 6 is a control circuit that controls the lighting of the slit light projector 30 and the operation of the galvano mirror 4 and the XY stage (xY table) 5;
Reference numeral 8 indicates an image processing circuit that processes image data input from the television camera 1, and 8 an image processing control device comprising a control circuit 6 and an image processing circuit 7.

The apparatus shown in FIG. 1 includes a television camera 1, a slit light projector 5, an xY stage (XY7''-pull) 5 on which a printed circuit board on which chip components to be inspected are mounted, and an image input from the television camera 1. The electronic component mounting board inspection apparatus is comprised of an image processing control device 8 that processes data and controls the system. A galvanometer mirror 4 controlled by an image processing control device 8 is provided to reflect the projected slit light and control the irradiation position of each slit light. By providing two television cameras 1 and a half mirror 2 so that the cutting line can be imaged in the horizontal direction, the shape of the optical cutting line in the image obtained by the television camera 1 is analyzed by the image processing control device 8. This is a chip component misalignment inspection device that detects misalignment of a chip component.

FIG. 2 is a partial explanatory diagram of the detection optical system of FIG. 1. 1st
The optical system shown in the figure consists of a television camera 1, a slit light projector 3, and a galvano mirror 4, and only two sets are prepared. Figure 2 shows one of the sets seen from the side. The figure shows. In FIG. 2, the same reference numerals indicate the same or corresponding parts throughout the drawings, 9 is the chip component to be inspected, 10 is the printed circuit board on which the chip component 9 is mounted, and the xY stage 5 (FIG. 1)
will be installed on the S11 is an input image obtained by capturing and inputting an image by the television camera 1 when the chip component 9 to be inspected is irradiated with a light cutting line by the slit light projector 6 via the galvanometer mirror 4.

The television camera 1 shown in FIG. 2 is installed perpendicularly to the substrate 10, and the light cutting line from the slit light projector 5 is reflected by the galvanometer mirror 4 and is irradiated onto the substrate 10 from an oblique direction. As a result, the light cutting line irradiated onto the chip component 9 at a position higher than the surface of the substrate 10 moves upward on the image 11 from the light cutting line irradiated onto the substrate surface. As described above, since the position of the optical cutting line on the image 11 changes depending on the unevenness of the target chip component 9, it is possible to detect the position of the target chip component 9 from the shape of the optical cutting line on the image 11. In the figure, positional deviation of the chip component 9 in the X direction can be detected. Since the height of the chip component 9 to be inspected differs depending on the type of the chip component 9, the galvanometer mirror 4 is used to irradiate the slit light so that the light cutting line is irradiated on the top surface according to the chip component 9 to be inspected. The slit light from the projector 5 is reflected to control the irradiation position. This method of controlling the galvano mirror 4 by the control circuit 6 (FIG. 1) is performed by controlling the angle of the galvano mirror 4 using data indicating the height of the chip component 9. Note that in order to detect the displacement of the chip component 9 in the Y direction as shown in the image 11 in FIG. 2, only one set of the optical system shown in FIG. 2 is separately prepared. For this purpose, two television cameras 1, a slit light projector 5, and a galvano mirror 4 shown in FIG.
The slit light projector 5 and the galvanometer mirror 3 are arranged so as to be perpendicular to each other as shown in FIG.

FIG. 5 is an explanatory diagram of the imaging method shown in FIG. 1. As for the television camera 1 shown in FIG. 1, as shown in FIG. Take an image with At this time, two TV cameras 1
Images a and 1h capture the same object in their images, but the image 11 input from the two television cameras 1α and 1b
is the input image 11α.

11A, they are orthogonal to each other. As a result, each X of the chip component 9 to be inspected is determined from the shape of the optical cutting line on the image as shown in images 11g and 11b in FIG.

It is possible to detect positional deviation in the Y direction.

FIGS. 4 and 5 are explanatory diagrams of 11 examples of each input image shown in FIGS. 2 and 6. FIG. In Figures 4 and 5,
12 is a high brightness point, and 15 is a high brightness vertical line.

14 is a high-brightness vertical line formed by a light cutting line, and 15 is a high-brightness vertical line formed by reflected light. The optical cutting lines in FIGS. 2 and 3 above are the input image 11 in FIG. 2 and the image 11g in FIG.
As shown in 11A, the television camera 1 is set so as to be horizontal in the image, and the image is captured. In this way, as shown in image 11 in FIG. 4, when the light cutting line irradiated onto the soldered board 10 of the target chip component 9 is reflected by the solder or metallic glossy surface on the board 10, This is imaged as a high-intensity point 12 in the image 11 of the television camera 1, and this generates a high-intensity vertical line 15, which can be easily distinguished from the light cutting line in terms of direction. On the other hand, if the image is captured so that the light section line is in the vertical direction in the image as shown in image 11 in FIG. Point 1
This is not preferable because it becomes difficult to distinguish it from the high brightness vertical 1i15 of 2. Next, a circuit configuration and an extraction method for stably extracting a light section line from an image when an image is captured by the television camera 1 so that the light section line is in the horizontal direction in the image will be described.

FIG. 6 is a schematic configuration diagram of the image processing circuit 7 including the optical section line extraction circuit shown in FIG. In FIG. 6, 16 is an A/B converter, 17 is an image memory, 18 is a light cutting line extraction circuit, 19 is a position storage memory, and 20 is a CPU.

21 is a memory, and 22 is a bus. The image signal input from the television camera 1 in FIG.
The signal is converted from analog to digital by the converter 16 and can be input to the image memory 17 or the optical cutting line extraction circuit 1B.

The optical cutting line extraction circuit 18 inputs image data from the A/D converter 16, performs optical cutting line extraction calculation, and outputs the calculation result to the position storage memory 19. The control circuit 6 is C
Controlled by PU 20, slit light projector 5
and galvano mirror 4 and XY stage (XY table) 5
control.

FIG. 7 is an explanatory diagram of the optical cutting line extraction method shown in FIG. 6. In FIG. 7, 11A is an image irradiated with a light cutting line;
B is an image not irradiated with a light cutting line, and 11C is a difference image. The optical cutting line extraction circuit 18 in FIG. 6 is the A/D converter 1.
Based on the image data from 6, subtraction is performed between the two images 11j and 11B using the image 11j shown in FIG. As a result, the only part that changes between the two images 11 and 4.11A is the irradiated part of the light cutting line, so only the light cutting line is separated from the background and a difference image 11C is created. The effects of reflected light can be removed. Furthermore, the coordinate I.

J are coordinates corresponding to the horizontal and vertical directions of the image, respectively.

FIG. 8 is an explanatory diagram of the brightness distribution of the difference image 11 (1') in FIG. 7. When the brightness distribution of the difference image 11 in FIG. As shown in the figure, the brightness value F (1) shows only a very small brightness level due to the influence of noise components, as the area other than the irradiated part of the optical cutting line by the slit light is canceled out. Therefore, a certain threshold value TH is set. By setting, it is possible to leave only the part of the light cutting line by the slit light.The change in brightness of the light cutting line part by this slit light shows a normal distribution change as shown in Fig. 8. Since the position on the image 11C of the light section line by this slit light is considered to be the center of this brightness distribution, the center value h at the coordinate I is calculated by the weighted average processing using the following formula.
(z) is calculated. Coordinate I here.

J is the coordinate corresponding to the horizontal and vertical directions of the image, respectively, as shown in FIG.

ΣF(J) screen 1 11° h(I) = (1) J.

Σp(t) j-j.

However, p (1) is the brightness value at coordinate J, J, *J
1 is the brightness value F (1) shown in Figure 8, and the threshold value TH
This is the coordinate value of the coordinate J when exceeding . By performing calculations using this equation (1) for each coordinate I, a light section line is extracted as the following point sequence.

(1, ff1(I) ) 7=0.1. ..., N
(2) However, N is the number of horizontal pixels of the image 11C.

FIG. 9 is an explanatory diagram of the brightness distribution of the difference image 11C of FIG. 7 in which there is a high-intensity vertical line 15 due to reflected light. Image 1 generated when a high-intensity point 12 is imaged by high-intensity reflected light during imaging by light cutting line irradiation as shown in Fig. 4 above.
There is a high brightness vertical line 15 above 1. In this case, the brightness value p (1
) exceeds the threshold value TH over the entire coordinate I, so the area to which equation (1) is applied covers a wide range. Therefore, W=7. -70 (3
) is a certain threshold value 11'T for the range W.
When H is exceeded (the calculation result using formula 13 is cleared for only the 15 minutes of the vertical line). This makes it possible to eliminate the influence of high-intensity reflected light when extracting the light cutting line of the high-intensity vertical line 15. According to the above algorithm The circuit configuration and operation of the optical cutting line extraction circuit 18 that performs the optical cutting line extraction process will be described next.

FIG. 10 is a block diagram of the circuit configuration of the optical cutting line extraction circuit 18 of FIG. 6. In FIG. 10, 25.24 is an image memory, 25 is an address generator, 26 is a clock generator, 27 is a differencer, 28 is an adder, 29 is a comparator 60 is a differencer, 61 is a multiplier, 52. 55 is an adder, 54°55
is a latch, 56 is a divider, 57 is a latch, and 38 is a gate.

The image signal input by the television camera 1 of FIG. 10 is digitized by the A/D converter 16 and stored in the image memory 25.24. At this time, the image 11A (FIG. 7) irradiated with the light cutting line is stored in the image memory 25, and the image 11B not irradiated with the light cutting line is stored in the image memory 24.
are stored sequentially. The clock generator 26 generates an address from the address generator 25 in the image memory 25.2 so that the image memory 25.24 can be accessed in the direction perpendicular to the scanning line.
Send to 4. A difference image 11 is obtained by subtracting the difference between the image 11J data of the image memory 23 irradiated with the light section line and the image 11B data of the image memory 24 that is not irradiated with the light section line by the subtractor 27.
8 and 9 by the subtractor 50.
The brightness value p(t) of the difference image 11C data shown in the figure
and a threshold value TH, and only data that is equal to or greater than the threshold value TH is processed by the next multiplier 51 and adder 62. That is, the multiplier 61 is the address generator 25
The product of the coordinate value J of the address generated by the subtractor 27 and the difference image 11C data F(J) via the subtractor 60 is calculated, and the adder accumulates this product F (1) + 1.
(1) Execute calculation of the numerator of formula. Further, the adder 62 outputs the difference image 11C data F from the subtractor 27 via the subtractor 50.
Accumulate C1) and calculate the denominator of formula 13.6
The results of each calculation are held in the latches 54 and 55, respectively, and the result of division M(1) by the divider 56 is latched in the latch 57 by the end command generated from the address generator 25 after vertical line scanning.
The center value X(Z) data based on equation (1) is output and stored in the position storage memory 19. The adder 28 uses the clock output from the clock generator 26 unless a carry occurs from the subtractor 60, that is, the arithmetic units 51 and 5.
2. As long as the calculation is executed in 55, cumulative addition is performed.

This cumulative result is always compared with the threshold value 11'TH of equation (3) by the comparator 29, and when the cumulative result becomes larger than the threshold value WTH, the latch 57 that holds the calculation result M(I)
At the same time, the address generator 25 is reset and updated to generate the next vertical address. Due to the action of this comparator 29, image data M(
I) can be cleared.

According to this embodiment, it is possible to detect the positional deviation of a small surface-mounted chip component mounted on a printed circuit board without being limited by the color and shape of the chip and the color of the printed circuit board. It is possible to eliminate the influence of vertical bright lines on the image sensor caused by high-intensity reflected light from metal surfaces such as solder on the substrate.

〔Effect of the invention〕

According to the present invention, it is possible to detect the positional deviation of a chip component without being limited by the color and shape of the chip component and the color of the printed circuit board, and it is also possible to eliminate the influence of reflected light from solder, etc. This has the effect of allowing highly reliable visual inspection of the mounted chip later.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the chip component positional deviation inspection device according to the present invention, FIG. 2 is a partial explanatory diagram of the detection optical system of FIG. 1, and FIG. Explanatory diagrams, Figures 4 and 5 are side views of each input image in Figures 2 and 3, and Figure 6
The diagrams are a schematic configuration diagram of the image processing circuit in Figure 1, Figures 7 and 8.
9 is an explanatory diagram of each optical section line extraction method shown in FIG. 6, and FIG. 10 is a block diagram of the optical section line extraction circuit shown in FIG. 6. 1・・・・・・・・・−・TV camera 2・・・・・・
...Half mirror 51001, -3910, slit light glow projector 4 ...... Galvano mirror 5 ...... XY stage 6 ...
......Control circuit 7... Image processing circuit 8...
・・・-・Control device

Claims (3)

[Claims] 1. Electronic component mounting board inspection equipment consisting of a slit light projector, a television camera, a table on which the printed circuit board to be inspected is mounted, and an image processing control device that processes image data input from the television camera and controls the system. In this method, two slit light projectors are arranged so that the light cutting lines irradiated onto the board on which the chip components are mounted are perpendicular to each other, and the projected slit light is reflected so that each slit light What is claimed is: 1. A chip component misalignment inspection device, characterized in that it is configured to detect misalignment of a chip component by providing a mirror whose irradiation position can be controlled. 2. The chip according to claim 1, characterized in that two television cameras are arranged so that each of the two light cutting lines irradiated onto the substrate can be imaged in a horizontal direction. Component misalignment inspection device. 3. A circuit that has a memory for storing each of an image irradiated with the light cutting line and an image not irradiated with the light cutting line, reads out the same position of each of these two images in a direction perpendicular to the scanning line, and calculates the difference between them. A chip component positional deviation inspection device according to claim 1, characterized in that the chip component positional deviation inspection device is provided with: