KR0164739B1 - Soldering test illumination apparatus & test method thereof for pcb - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting apparatus and inspection method for soldering inspection of a printed circuit board. In particular, an illumination apparatus having polarization illumination and indirect illumination in four directions is provided, and an ink image of a substrate using polarization illumination of the illumination apparatus is provided. Then, the raw images obtained by indirect lighting and binary operation are binary-operated to obtain lead images. The lead images and mask images are calculated to obtain an initial image, and then processed by morphological equations to examine the bridge.

In addition, the blowholes are examined by the raw image and the mask image.

Description

Lighting device and inspection method for soldering inspection of printed circuit board

1 is a perspective view of the lighting apparatus of the present invention.

(A) of FIG. 2 is a front sectional view of the lighting apparatus of the present invention, and (b) is a layout view of the polarized light of the lighting apparatus of the present invention.

3 is a raw image of a printed circuit board according to the present invention.

4 is a mask image of a printed circuit board according to the present invention.

(A) of FIG. 5 is an image of a printed circuit board when only polarized light of 0 degree position is irradiated, and (b) is an image of a printed circuit board when only polarized light of 180 degree position is irradiated. (C) is an image of a printed circuit board when only polarized light at 90 ° is irradiated, and (d) is an image of a printed circuit board when only polarized light at 270 ° is irradiated.

6 is an ink image according to the present invention.

7 is a lead image according to the present invention.

8 is an initial image during the bridge inspection according to the present invention.

9 is an intermediate image in which the initial image above is maximized.

FIG. 10 is a bridge image with the intermediate image cut to the maximum.

11 is a blowhole image according to the present invention.

12 is a block diagram showing the inspection process of the bridge according to the present invention.

13 is a block diagram showing the inspection process of the blowhole according to the present invention.

FIG. 14A is a partial cross-sectional view of a printed circuit board having blow holes, and FIG. 14B is a partial plan view of a printed circuit board having bridges.

* Explanation of symbols for main parts of the drawings

1 cover 10 perspective

11: test block 12; Rough Paint

2: indirect illumination 20: translucent filter

3: polarized light 30: polarized filter

4: image processing computer 40: camera

5: substrate 50: inspection area

6: part 7: lead

70: bridge 71: blowhole

8: ink

The present invention is to inspect the soldering failure in the PCB (Throvgh The Hole) type of printed circuit board, in particular irradiating a plurality of polarized light independently on the printed circuit board in the inspection area of the camera connected to the image processing computer. The present invention relates to a lighting device for soldering inspection of a printed circuit board, which enables the inspection and indirect illumination irradiation.

The present invention also separates the ink image engraved with figures or letters on the substrate using the polarized light and then processes it by morphology to examine the bridges between the solders separated from each other, and to check the indirect lighting. The present invention relates to a soldering inspection method of a printed circuit board which inspects blowholes of soldering by using the same.

In general, a completed insertion type printed circuit board (hereinafter, referred to as a substrate) is inspected for bridges and blowholes.

This is for detecting a solder failure, for example, in FIG. 14 (a), the lead 60 of the component 6 is not sufficiently in contact with the lead 7, and a lack is formed on the right side.

This is called a blowhole 71, which may be disconnected during use.

14 (b) shows that the bridge 70 is generated between the lead 7 separated from each other, which means a short between the two lead.

In order to check the soldering defect as described above, conventionally, the existence of the bridge between the two leads 7 is determined by using the window 9 shown as a virtual line in FIG.

However, there is a problem that identification is difficult when the bridge is generated by bypassing the window 9.

In addition, when inspecting blowholes by using an image processing computer, the lighting is directly irradiated to the inspection area of the substrate caught by the camera. Therefore, it takes a long time to identify the blowholes by being caught by the camera such as lead and ink images. There was this.

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and an object thereof is a printed circuit having polarized light irradiated independently from all directions in irradiating light to an inspection region of a substrate, and having an indirect light irradiated from all directions. The present invention provides an illumination device for solder inspection of a substrate.

Another object of the present invention is to separate the ink image from the substrate using the polarized light and then to process it by a morphological technique to inspect the bridge, and to examine the blowhole by irradiating the substrate with indirect illumination. The present invention provides a soldering inspection method.

In order to achieve the above object, the present invention provides a hemispherical cover formed with a test hole including a test area of a substrate in a lower part of the perforation for the camera at the upper part, and the inner surface of the cover is irradiated and then reflected into the test hole. A plurality of indirect illuminations disposed radially on the inner circumference of the cover, a semi-transparent filter covering the upper part of the indirect illumination, a plurality of polarization illuminations arranged at equal intervals inside the cover and directly irradiating the inspection tool, And a polarizing filter attached to each polarized light.

The present invention also provides a polarized light at 0 °, 90 °, 180 °, and 270 ° positions when inspecting an inspection area on an engine using an image processing computer that recognizes a bright part as 1 and a dark part as 0 in an image through a camera. Each of the lights individually to obtain I ₀ , I ₉₀ , I ₁₈₀ , I ₂₇₀ images, (I ₀ images AND I ₁₈₀ images) OR (I ₉₀ images AND I ₂₇₀ images) = obtaining images And irradiating only the indirect illumination to the inspection area of the substrate to obtain a raw image, (ink image NOT) AND (raw image) = obtaining a lead image, and mask image which is a standard position of lead in the inspection area of the substrate. There is another feature that consists of setting and obtaining (lead image) OR (mask image) = initial image.

In another aspect, the present invention is to repeat the diglation of the morphological method to the initial image dozens of times to obtain an intermediate image until the mask becomes a lead-like shape, and the morphological recognition method of the intermediate image Another feature consists of obtaining a bridge image by repeating the erosion a few dozen times.

The present invention also has another feature of NOT operation of the raw image, and AND operation of the operation value and the mask image to obtain a blowhole image.

The present invention also has another feature of NOT operation of the raw image, and AND operation of the operation value and the mask image to obtain a blowhole image.

According to the present invention having the above characteristics, when the inspection of the bridge to obtain an ink image by using each polarized light of the illumination device, and then obtained a lead image by binary operation with the raw image obtained by indirect illumination.

The lead image thus obtained is binarized with the mask image to obtain an initial image.

In addition, the initial image is finally obtained through the coating and mowing operation of the morphological method.

In addition, when the blowhole is inspected, the raw image obtained by the indirect lighting is binaryly calculated, and then binaryly computed again with the mask image to obtain the blowhole image.

In the above process, each image represents a binary image of an image processing computer which recognizes that a light portion is 1 and a dark portion is 0 among images obtained through a camera.

In addition, morphology in the above process refers to a method of finding a feature from the change while processing a digitally captured image image.

Representative shape processing operations include erosion and dialation.

In this case, clipping refers to making a pixel 0, which was 1 of the outer body of an object composed of several pixels in a binary image of an object 1 and a background 0.

If you cut it once or twice, you don't feel the difference, but if you repeat it several times, only one pixel, which is the center of the object, remains, so you can find the center of the object.

In addition, coating refers to making a pixel, which was 0 of the outer surface of the object, as opposed to mowing.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of the lighting apparatus of the present invention.

The device according to the present invention has a hemispherical cover (1) having a test hole (11) including a test area (50) of a substrate (5) formed in the upper center and a through hole (10) for the camera (40). It is also provided with a plurality of indirect illumination (2) radially on the inner periphery of the cover so that the inner surface of the cover (1) is irradiated and then reflected by the inspection port (11).

And the polarizing light 3 which irradiates the inspection opening 11 directly to the inner surface of the substantially center position of a cover is provided.

The polarized light 3 is located in four places at 90 ° intervals as shown in FIG.

In addition, a semi-transparent filter 20 is provided to cover the upper portion of the indirect illumination 2 so that light is dispersed, and a polarization filter 30 is provided in each polarization light 3.

And rough paint 12 was applied to the inner surface of the cover 1 in order to diffuse the reflection of the indirect illumination (2).

The device of the present invention configured as described above, the indirect illumination (2) and the polarization inside the hemispherical cover (1) in order to process the image of the substrate through the camera 40 as a binary image to the image processing computer (4) The lighting (3) was provided.

The indirect illumination (2) is irradiated through the translucent filter 20 to the inner surface of the cover 1 in a light spread state, in which the diffuse reflection caused by the rough paint 12 of the inner surface inspection ( 11).

Therefore, the inspection area 50 of the substrate can be irradiated evenly in all directions, allowing the image processing computer 4 to recognize the raw image to be described later.

In addition, the polarized light (3) is irradiated through the polarization filter 30 to the inspection area 50 of the inspection sphere only in a certain direction, the specific direction is the inspection area in the 90 ° intervals where the polarization illumination is installed To be surveyed towards

This allows the image processing computer 4 to recognize I ₀ , I ₉₀ , I ₁₈₀ , and I ₂₇₀ images which will be described later.

In addition, a method of inspecting the inspection area 50 on the substrate 5 by the image processing computer 4 using the above lighting apparatus will be described below.

In the inspection area of the substrate using the binary image of the image processing computer 4 which recognizes the bright part 1 and the dark part 0 in the image through the camera 40, the 0 ° position with all the lights turned off. Only the polarized light 3 of is irradiated to the inspection region of the substrate to obtain an I ₀ image as shown in FIG.

At this time, the ink image of the letters R, C, and resistors appear bright due to their characteristics, whereas the lead angles are different from each other depending on the angle of polarization, so that only the right side of the lead appears bright when irradiated with 0 ° position.

In the figure, the bright part is 1 and the dark part is 0.

Here, when looking at the characteristics of the substrate, when the polarized light (3) of the right side is irradiated as shown in Fig. 2 (a), the total surface reflection of the ink (8) while the surface of the lead (7) according to the angle of incidence It can be seen that reflection occurs.

Therefore, the lead image appears differently depending on the irradiation position of the polarized light, while the ink image appears the same.

Subsequently, the polarized light 3 at 180 ° is irradiated with all the lights turned off to obtain the I ₁₈₀ image as shown in FIG. 5 (b).

At this time, only the lead side parts of the left side appear bright.

In addition, the polarized light 3 at the 90 ° position is irradiated with all the lights turned off to obtain the I ₉₀ image as shown in FIG.

At this time, only the upper sides are bright.

Also, the letters R, C and resistors, which are ink images, naturally appear bright.

Then, with all the lights off, the polarized light 3 at 270 ° is irradiated to obtain an I ₂₇₀ image as shown in FIG. 5 (d).

At this time, only the lower sides are bright.

In addition, each of the above images is binarized.

(I ₀ image AND I ₁₈₀ image) OR (I ₉₀ image AND I ₂₇₀ image)

By performing the calculation as described above, an ink image as shown in FIG. 6 can be obtained.

In addition, only the indirect illumination 2 is irradiated to the inspection area of the substrate while all the lights are turned off to obtain a raw image as shown in FIG.

This original image shows that the ink and lead are all shining brightly.

Further, the NOT image of the ink image is ANDed, and then the AND and the raw image are ANDed to obtain a pure lead image as shown in FIG.

In addition, a mask image, which is a standard position of the leads in the inspection region of the substrate, is set as shown in FIG.

In addition, an OR operation of the mask image and the lead image is performed to obtain an initial image of removing blow holes that may be formed in the lead.

The initial image is shown in FIG.

In addition, the mask image is embedded in the lead image by repeating the operation of applying the morphological formula to the initial image several times.

In this way, the mask image is shaped like a lead image to obtain an intermediate image as shown in FIG.

In addition, the intermediate image is clipped by the morphological technique.

Dozens of repetitions result in bridges that were connected between the two clumps of lead, resulting in a bridge image as shown in FIG.

The series of steps is well illustrated in the block diagram of FIG.

In addition, by performing NOT operation on the raw image of FIG. 3 and ANDing the operation value and the mask image of FIG. 4, a blowhole image as shown in FIG. 11 can be obtained.

The process of obtaining the blowhole image is shown in FIG.

As described above, according to the present invention, a polarized light is used to separate an ink image from an inspection area of a substrate, and a binary image of the raw image obtained by using indirect illumination and the ink image is obtained to obtain a lead image. After calculating the mask image to obtain the initial image, the initial image is computed by the morphological method to inspect the bridge of the substrate.

In addition, the binary inspection of the raw image and the mask image finds the blowhole, and therefore, the soldering inspection is more precise, thereby providing the advantage of improved reliability.

Claims (6)

In irradiating light to the soldering inspection area of the printed circuit board, a hemispherical cover having a test hole including an inspection area of the printed circuit board is formed in the upper part of the perforation hole for the camera, and the inner surface of the cover A plurality of indirect lights radially disposed on the inner circumference of the cover so as to be reflected back to the inspection port, a semi-transparent filter covering the upper part of the indirect light, and arranged at equal intervals inside the cover to directly irradiate the inspection port. And a plurality of polarization lights and a polarization filter attached to each of said polarization lights. 2. The lighting apparatus for soldering inspection of a printed circuit board according to claim 1, wherein a rough paint for diffusely reflecting indirect illumination is applied to the inner surface of the cover. 2. The lighting apparatus for soldering inspection of a printed circuit board according to claim 1, wherein the polarized light is arranged at equal intervals on all sides of the inner side of the cover. When inspecting the inspection area on the substrate by using an image processing computer that recognizes the bright part as 1 and the dark part as 0 in the image through the camera, only the 0 ° polarized light is irradiated to the inspection area of the substrate to detect the I ₀ image. Obtaining the I ₁₈₀ image by irradiating only the 180 ° position of the polarized light to the inspection area of the substrate, obtaining only the 90 ° of the polarized light position of the inspection area of the substrate to obtain the I ₉₀ image, and 270 ° Irradiating only the polarized light of the position to the inspection area of the substrate to obtain an I ₂₇₀ image, ANDing the I ₀ image and the I ₁₈₀ image, ANDing the I ₉₀ image and the I ₂₇₀ image, and then calculating the two operation values. OR operation to obtain an ink image, irradiating only the indirect illumination to the inspection area of the substrate to obtain a raw image, and NOT computing the ink image, and then ANDing the operation value and the raw image. Obtaining a lead image, setting a mask image which is a standard position of lead in the inspection area of the substrate, and ORing the lead image and the mask image to obtain an initial image from which blow holes are removed. Soldering test method for a printed circuit board, characterized in that. The method of claim 4, further comprising repeating a coating operation of the morphological technique on the initial image several times and obtaining an intermediate image until the mask becomes large like a lead, and cutting the morphological technique on the intermediate image. A soldering inspection method for a printed circuit board, comprising the steps of obtaining a bridge image by repeating the operation several times. 5. The soldering inspection method of claim 4, wherein the operation comprises performing an NOT operation on the raw image, and performing an AND operation on the operation value and the mask image to obtain a blowhole image. 6.