JP3104152B2 - Soldering condition inspection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting the condition of a soldered portion of an electronic component or a discrete component mounted on a printed circuit board to be inspected. The present invention relates to a soldering state inspection method and apparatus capable of extracting an inspection image of only a soldering portion of a component and easily and quickly inspecting the quality of the soldering state.

[0002]

2. Description of the Related Art A conventional soldering state inspection method of this type is:
For example, as described in JP-A-61-293657, illumination is performed by a plurality of ring-shaped illuminating means arranged in a dome shape above the inspection object, and an image is taken by a television camera from above the dome. There has been proposed a method in which image processing is performed, the above-mentioned ring-shaped illuminating means of a plurality of stages are sequentially turned on to switch the illuminating angle, and the quality of the soldering state is judged comprehensively from the image characteristics obtained each time. Then, the plurality of ring-shaped illumination units perform, for example, vertical epi-illumination, oblique illumination, and horizontal illumination, respectively, and perform inspection images under each illumination condition with a television camera. To determine the quality of soldering. In this case, a threshold is determined at a certain level for each of the inspection images under each illumination condition, and the image is binarized.
For example, the quality of the soldering state is determined by comprehensively determining changes in the shape and area of a brightly lit portion of each of the binary images.

[0003]

However, in such a conventional soldering state inspection method, a threshold value is determined for each inspection image photographed by appropriately changing the illumination angle of a plurality of illumination means. In order to judge the quality of the soldering state by comprehensively judging the image characteristics of each binarized image, first, a certain level of binarization for each inspection image was performed. It was difficult to determine the threshold. That is, it is difficult to determine a threshold value for extracting an image of only a necessary soldered portion in a state where an image of a component other than the soldered portion or a background portion is photographed. Therefore, depending on how to determine the threshold value at a certain level, an unnecessary image other than the soldered portion is also extracted, and a binarized image in which only the actually required soldered portion is extracted may not be obtained. . For this reason, it was difficult to judge the quality by comprehensively judging the image characteristics of the binarized image obtained at each illumination angle, and it required skill and time was required for the inspection.

Accordingly, the present invention addresses such a problem and extracts an inspection image of only a soldered portion of an electronic component mounted on a printed circuit board to easily and quickly determine whether or not the soldered state is good. It is an object of the present invention to provide a method and an apparatus for inspecting a soldering state which can be inspected.

[0005]

In order to achieve the above object, a soldering state inspection method according to the present invention is directed to an upper illumination for illuminating an electronic component mounted on a printed circuit board to be inspected from substantially vertically above. Alternatively, the oblique illumination to be illuminated from obliquely above is performed by switching, and an image captured by the upper illumination and an oblique illumination of the target component are respectively captured by an imaging device positioned substantially vertically above the target component, and a signal of the upper illumination image is obtained. When
A sum image is created by adding the signal of the oblique illumination image, and
By extracting the inspection image of only the perforated part of the soldered part,
The quality of the soldering condition of the target component is determined based on the inspection image .

Further, the soldering state inspection apparatus used for carrying out the inspection method described above includes an upper illumination section for illuminating an electronic component mounted on a printed circuit board to be inspected from substantially vertically above and an illumination from obliquely above. An illumination device having an oblique illumination portion to be switched and capable of lighting each of the illumination portions; and an imaging device which is located above the illumination device and captures an upper illumination image and an oblique illumination image of the target component from substantially vertically above the target component. Device, a plurality of storage devices for respectively storing the upper illumination image and the oblique illumination image output from the imaging device, and a signal of the upper illumination image and a signal of the oblique illumination image read from these storage devices.
Addition to create a sum image, which is used to make a hole in the soldered part
An image calculation unit that extracts only the inspection image, an image display that displays a calculation image obtained as a result of calculation by the image calculation unit,
And a control circuit for controlling the operation of each of the above components.

[0007]

The soldering state inspection apparatus thus configured is:
An illumination device that has an upper illumination unit and an oblique illumination unit and that can switch on and off each of the illumination units enables illumination of an electronic component mounted on a printed circuit board to be inspected from approximately vertically above or obliquely from above. An illumination is performed, an upper illumination image and an oblique illumination image of the target component are respectively taken from substantially vertically above the target component by an imaging device located above the illumination device, and the upper illumination output from the imaging device by a plurality of storage devices. The image and the oblique illumination image are stored, respectively, and the signal of the upper illumination image and the signal of the oblique illumination image read out from the storage device by the image calculation unit.
Is added to create a Japanese image, which is
The operation is performed so as to extract the inspection image of only the part, and display the operation image of the result calculated by the image operation part by the image display. Then, the inspection image of only the soldered portion of the target component is extracted and displayed on the basis of the operation image, and the quality of the soldered state can be easily and quickly inspected.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing an embodiment of a soldering state inspection method according to the present invention. This soldering state inspection method is for inspecting the quality of a soldered portion such as an electronic component or a discrete component mounted on a printed circuit board to be inspected. The illuminating device 3 illuminates the electronic component 2 that has been used. At this time, the illumination performed by the illumination device 3 is performed by switching between an upper illumination 4 that illuminates the electronic component 2 substantially vertically above and an oblique illumination 5 that illuminates the electronic component 2 obliquely from above.

Next, an image by the upper illumination 4 and an image by the oblique illumination 5 of the electronic component 2 are respectively photographed by the imaging device 6 located substantially vertically above the electronic component 2 as the target component. This is because the illumination by the illumination device 3 is switched, the upper illumination 4 alone is used to illuminate the electronic component 2, and the electronic component 2 is photographed to detect the upper illumination image 7, and the oblique illumination 5 is used to illuminate the electronic component 2 only. The oblique illumination image 8 is photographed and detected.

Next, these upper illumination image 7 and oblique illumination image 8
Are taken into an image calculation unit 9, and the image calculation unit 9 calculates a signal 10 of the upper illumination image 7 and a signal of the oblique illumination image 8 to generate a calculation image 10. As the operation image 10
Is a sum image obtained by adding the signal of the upper illumination image 7 and the signal of the oblique illumination image 8. In this sum image , the soldering portion 1 of the electronic component 2 is determined due to the difference in light irradiation between the upper illumination 4 and the oblique illumination 5.
Since the luminances of the reflected light from the first and other portions are different from each other, an image in which the components other than the soldered portion 11 and the background portion have disappeared can be obtained by the calculation.

[0011] Then, by using the operation image 10, to determine the quality of the soldering state of the electronic component 2 by the inspection image extracted from the soldering section 11 (12).

[0012] Here, a description will be given to the determination of the quality of detection and soldering state of the inspection image. Here , FIG. 2 (a) to FIG. 2 (a) show a state in which a perforated portion generated in a soldered portion is inspected using a sum image in soldering of a lead wire .
This will be described with reference to FIG. FIG. 2A shows an inspection target in this case, in which a lead wire 15 projects upward and is soldered to the printed circuit board 1, and a vertical hole 16 is formed in the soldered portion 11. Suppose you are. In this state, if the image is shot by irradiating only the upper illumination 4 in FIG. 1, an upper illumination image as shown in FIG. 2B is obtained. In this upper illumination image, the illumination light is reflected laterally at the soldered portion 11 whose surface is inclined, no reflected light is generated from the perforated portion 16, and the soldered portion 11 and the perforated portion 16 Illumination light is reflected upward on the upper surface of the lead wire 15 which looks dark (low brightness) as shown by hatching in the figure and has a substantially flat surface, and the portion of the lead wire 15 is outlined in the figure. It looks bright (high brightness) as shown.

Next, when photographing is performed by irradiating only the oblique illumination 5 in FIG. 1, an oblique illumination image as shown in FIG. 2C is obtained. In this oblique illumination image, the illuminating light is reflected upward by the soldered portion 11 whose surface is inclined, and the soldered portion 11 looks bright (high brightness) as shown by a white outline in FIG. The illumination light is reflected laterally on the upper surface of the lead wire 15 which becomes flat, and no reflected light is generated from the perforated portion 16. The portion of the lead wire 15 and the perforated portion 16 are hatched in the figure. Appears dark (low brightness) as shown.

Next, the image calculation unit 9 shown in FIG.FIG.
The signal of the upper illumination image shown in (b) and the oblique illumination shown in FIG.
Add the signal of the bright imageFIG.Sum as shown in (d)
Get an image. In this Japanese image, the soldered portion 11 and the lead
In the area of the line 15, the calculation results are each a large positive value.
It looks bright as shown in the white outline in the figure,
In the area of No. 16, the calculation result is a very small value and
It looks dark as shown with diagonal lines crossing in two directions.
At this time, the calculation result is also plotted for the surrounding background image.
Large values, and all looks bright. As a result,
FIG.Perforated portion 1 generated in soldering portion 11 shown in FIG.
Only six inspection images are extracted. This allows the solder
At a glance, it is clear that a perforated portion 16 has occurred in the attachment portion 11.
NaturallyUnderstands whether the soldering condition is good or bad.

FIG . 3 is a block diagram of an overall configuration showing an embodiment of an inspection apparatus used for performing the above-mentioned soldering state inspection method. As shown in FIG. 3 , the soldering state inspection apparatus includes an illumination device 3, an imaging device 6, an A / D converter 17
And two image memories 18a and 18b, and an image operation unit 9
, An image display 19, a control circuit unit 20, an operation determination unit 21, a reference value memory 22, and an output device 2.
3 is provided.

The illuminating device 3 illuminates the electronic component 2 mounted on the printed circuit board 1 to be inspected from substantially vertically above (4) the upper illuminating section and obliquely from above (5).
It has an oblique illumination section and switches each of the illumination sections so that it can be turned on. The specific structure is as shown in FIG . That is, a disk-shaped cap member 25 having a photographing hole 24 for visual inspection of the electronic components 2 and the like mounted on the printed circuit board 1 to be inspected at the center, and the same lower surface side of the cap member 25 A plurality of luminous bodies (LEDs 26a) of a first group A which are arranged in a plurality of concentric circles in an area near the center with the photographing hole 24 as the center in the plane and illuminate the target component from substantially vertically above; A large number of light-emitting bodies (LEDs 26b) of a second group B which are arranged concentrically in a region near the outer periphery with the shooting hole 24 as a center and illuminate the target component from obliquely above; 2
4 and a light-diffusing smoke plate 28 attached to the lower central portion of the cap member 25.
A diffuse reflection plate 29 protruding inward and obliquely downward at the entire periphery of the periphery of the cap member 25; and an upper illumination power supply 30 for supplying power to the large number of LEDs 26a of the first group A. And an oblique illumination power supply 31 for supplying power to a large number of the LEDs 26b of the second group B. The upper illumination section is formed by the LEDs 26a of the first group A, and the oblique illumination section is formed by the LEDs 26b of the second group B. Note that, in FIG.
Indicates a mounting bracket for suspending the smoke plate 28 below the cap member 25. The upper illumination power supply 30 and the oblique illumination power supply 31 are connected to a control circuit unit 20, as shown in FIG. 3 , and the control circuit unit 20 controls the power on / off operation. ing.

The image pickup device 6 captures an upper illumination image of the electronic component 2 illuminated by the upper illumination 4 and an oblique illumination image illuminated by the oblique illumination 5 from substantially vertically above the electronic component 2. It is located above the central part of the lighting device 3 and comprises, for example, a television camera or a CCD camera. And
The A / D converter 17 inputs an image signal photographed and output by the imaging device 6 and converts the image signal into a digital signal. The switching of the shooting of the upper illumination image or the oblique illumination image by the imaging device 6 is performed by controlling the ON operation of the upper illumination power supply 30 and the oblique illumination power supply 31 under the control of the control circuit unit 20, and switching the upper illumination 4 and the oblique illumination 5 Is performed by switching between.

The first image memory 18a serves as a storage device for storing the data of the upper illumination image output from the A / D converter 17, and the second image memory 18b stores the data of the A / D converter. The storage device stores the data of the oblique illumination image output from the container 17. The switching between the image memories 18a and 18b is switched in synchronization with the switching of the ON operation between the upper illumination power supply 30 and the oblique illumination power supply 31 under the control of the control circuit unit 20.

The image calculation section 9 inputs the data of the upper illumination image and the data of the oblique illumination image read from the first and second image memories 18a and 18b, and calculates and calculates the image data. It intended to create an image, UeTeru
Adds bright image data and oblique illumination image data to create a Japanese image
An image is created and this allows inspection of only the perforated part of the soldered part.
An image is to be extracted . At this time, in the calculation operation of the image calculation unit 9, the control is performed by the address control from the control circuit unit 20 so that the calculation is performed between the data of the same pixels in the upper illumination image and the oblique illumination image. .

The image display 19 displays an operation image obtained as a result of the operation by the image operation section 9, that is, a sum image, and comprises, for example, a television monitor. And the operator
By observing the sum image displayed on the image display 19, the quality of the soldering state or the presence or absence of a perforated portion of the solder is determined based on the image.

The control circuit section 20 controls the operation of each of the above-described components as described above.
(Central processing unit).

Further, on the output side of the image calculation unit 9,
An operation determination unit 21 is provided. This operation determination unit 21
Calculates the areas of the bright and dark areas for the computed image obtained by the image computing unit 9 and compares the calculation result with a reference value of the area of the bright and dark areas prepared in advance to determine the soldering state of the target component. Is determined. The reference value memory 22 stores the reference value of the area of the light and dark area of the image to be compared by the calculation judgment unit 21 and sends it out to the calculation judgment unit 21. (Write / read memory as needed). And the output device 23
Automatically outputs the result of the soldering state of each target component determined by the calculation determining unit 21.
For example, it comprises a television monitor or a printer. In the case where the calculation determination unit 21, the reference value memory 22, and the output device 23 are provided, the operator observes the calculation image displayed on the image display 19 and does not judge each of the calculation images. The judgment result can be output automatically.

By the operation of the soldering state inspection apparatus thus configured, the soldering state inspection method described with reference to FIG. 1 is performed, and a sum image as shown in FIG. It is possible to determine the presence or absence of the perforated portion 16 generated in the soldered portion 11 in the soldering of the wire 15.
It is necessary to calibrate the brightness of the upper illumination 4 and the oblique illumination 5 by the illumination of the illumination device 3 before inspecting using the soldering state inspection device. That is, in FIG. 3 , for example, a white diffuse reflector is set horizontally below the illuminating device 3 instead of the printed circuit board 1, and the diffuse reflector is illuminated by switching between the upper illumination 4 and the oblique illumination 5. .
Then, in this state, the diffuser reflector is photographed by the imaging device 6, and the upper illumination is performed so that the luminance of the captured image irradiated by the upper illumination 4 and the luminance of the captured image irradiated by the oblique illumination 5 have a fixed relationship. 4 and the brightness of the oblique illumination 5 are adjusted. The above predetermined relationship constant, or the luminance B ₂ of the photographic image of the luminance B ₁ and oblique illumination 5 photographed image above illumination 4 is made to be the same, in both as B ₁ = B ₂ + ΔB And the brightness difference ΔB is made variable. Especially like the latter, B
_{When a} constant brightness difference ΔB is provided between ₁ and B ₂ , in the actual inspection of the printed circuit board 1, the inspection can be performed without accurately determining the level of the printed circuit board 1.

[0024]

The present invention has been configured as described above.
Perform oblique illumination for illuminating the illumination or oblique upward on to illuminate the substantially vertically above the electronic components mounted on the test object on the printed board by switching respectively, in an imaging device located substantially vertically above the target component An image of the target component by the upper illumination and an image by the oblique illumination are respectively taken, and an addition operation is performed between the signal of the upper illumination image and the signal of the oblique illumination image.
A calculation image is created by the calculation, and the quality of the soldering state of the target component can be determined using the calculation image. At this time, the hole in the soldered part of the target component is
It is possible to extract and display the inspection image of only the welded portion and easily and quickly inspect the quality of the soldered state. Therefore, it is not necessary to determine a threshold value for each inspection image at each illumination angle and to binarize the inspection image as in the related art, and to extract unnecessary images other than the soldered portion, without skill, and without any skill. In addition, the inspection of the soldering state can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a soldering state inspection method according to the present invention.

FIG. 2 is generated in a soldered portion when soldering a lead wire
Showing the inspection status of the perforated part using a Japanese image
FIG.

FIG. 3 shows an inspection used to carry out the above-mentioned soldering state inspection method.
It is a block diagram of the whole composition which shows an example of an inspection device.

FIG. 4 is an explanatory cross-sectional view showing a specific structure of the lighting device.
You.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Printed circuit board 2 ... Electronic component 3 ... Illumination device 4 ... Top illumination 5 ... Oblique illumination 6 ... Imaging device 9 ... Image calculation part 11 ... Soldering part 16 ... Perforated part 17 ... A / D converter 18a, 18b ... Image memory 19 ... Image display 20 ... Control circuit unit 21 ... Calculation judgment unit 22 ... Reference value memory 23 ... Output device 30 ... Top illumination power supply 31 ... Oblique illumination power supply

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 21/84-21/958

Claims (2)

(57) [Claims] 1. An electronic component mounted on a printed circuit board to be inspected is switched between an upper illumination for illuminating substantially vertically above and an oblique illumination for illuminating obliquely above, so that the electronic component is mounted substantially vertically above the target component. The image of the target component is photographed with the upper illumination and the oblique illumination with the imaging device located, and the signal of the upper illumination image and the signal of the oblique illumination image are added.
To create a Japanese image.
A method for inspecting a soldering state , comprising extracting an inspection image of the target component and determining whether the soldering state of the target component is good or not based on the inspection image . 2. An upper illumination section for illuminating an electronic component mounted on a printed circuit board to be inspected from substantially vertically above and an oblique illumination section for illuminating obliquely from above, and each of the illumination sections can be switched and turned on. An illuminating device, an imaging device positioned above the illuminating device and capturing an upper illumination image and an oblique illumination image of the target component from substantially vertically above, respectively, an upper illumination image and an oblique illumination output from the imaging device A plurality of storage devices each storing an image, and a signal of an upper illumination image and a signal of an oblique illumination image read from these storage devices are added.
To create a Japanese image, which allows only the perforated part of the soldered part
An image calculation unit for extracting an inspection image, an image display for displaying a calculation image obtained as a result of the calculation performed by the image calculation unit, and a control circuit unit for controlling the operation of each of the components. Soldering condition inspection device.