JPH0210251A - Board checking apparatus - Google Patents

Abstract

PURPOSE:To detect poor soldered parts positively at a high speed with a simple apparatus by illuminating the soldered part, photographing the image of said part, counting the number of bright regions, and judging the quality thereof. CONSTITUTION:A ring shaped lighting device 3 is provided so that an electronic part 2 is uniformly illuminated. The image of a printed board 1 on which the electronic part 2 is mounted is picked up with a video camera 4. The obtained image signal undergoes A/D conversion in an image binary coding circuit 5. The signal is further binary-coded with a luminance value. The binary coded image signals are processed as follows: the picture elements in the bright area are collected so that the picture elements at the upper and lower parts and right and left parts are gathered together with an area extracting circuit 6; and the number of bright regions 9 which cannot be collected in the same area at the final stage is counted. Thus the number of the regions 9 is inputted into a judging circuit 7. The number is compared with the number of the regions 9 in a good soldered part 8 which is picked up beforehand and used as a stored reference. When the number of the regions 9 obtained in the circuit 6 is larger than the reference number of the regions 9, the product is judged as a defective product. When the number is small, the product is judged as a good product.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a board inspection device for inspecting the condition of soldered parts on a printed circuit board.

BACKGROUND OF THE INVENTION Conventional board inspection apparatuses have been used to inspect objects for misalignment, missing parts, etc. by illuminating the object, but none have been able to inspect the condition of soldering parts. Therefore, inspection of the soldered portions of electronic components and the like on the board has been performed by visual inspection by an operator.

Problems to be Solved by the Invention However, in today's world, where components on printed circuit boards are becoming smaller and more densely packaged, it is difficult for workers to continue inspecting very fine soldered parts for long periods of time. In addition to being extremely difficult, there was a problem in that the test results varied greatly depending on the skill level and fatigue level of the operator.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a board inspection device that can inspect soldering parts without relying on an operator.

Means for Solving the Problems In order to solve the above problems, the present invention provides an illumination means for illuminating a printed circuit board, a video camera for capturing an image of the printed circuit board, and converting an image signal imaged by the video camera into a binary image signal. an area extraction circuit that counts the number of areas in the part corresponding to the soldering area using the image signal converted into a digital image signal by the image binarization circuit; The apparatus includes a determination circuit that compares the number of areas obtained by the area extraction circuit with a reference number of areas to determine whether the soldering part is good or bad.

Effect of the Invention With the above configuration, the present invention enables defective soldering parts to be detected quickly and reliably using a simple device. Furthermore, the visual inspection of soldering parts, which conventionally required a great deal of labor, can be automated, and inspection efficiency can be greatly improved.

Furthermore, only one imaging system is required to realize the present invention, and the apparatus can be made compact.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a board inspection apparatus according to an embodiment of the present invention. A ring-shaped illumination device 3 and a video camera 4 are arranged directly above a printed circuit board 1 on which an electronic component 2 is mounted so that their axes are the same. Then, the output of the video camera 4 is connected to an image binarization circuit 5, the output of the image binarization circuit 5 is connected to a region extraction circuit 6, and the output of the region extraction circuit 6 is further connected to a determination circuit 7. There is.

Before explaining the operation of the above configuration, the principle used in the present invention will be explained.

FIG. 2 shows the situation when the parts with good soldering and the parts with bad soldering are illuminated and imaged with the video camera 4 from directly above. Here, FIG. 2(a) shows the case of good soldering, and FIG. 2(b) shows the case of bad soldering. Also,
FIG. 3 shows a cross-section of a section with good soldering and a section with poor soldering.

Here, FIG. 3(a) shows the case of good soldering in parts, and FIG. 3(b) shows the case of bad soldering in parts.

The surface of a good soldered part is smooth and shiny, as shown in Figure 3(a). Therefore, when an image is captured by a video camera, a small number of large and bright areas 9 are captured in the soldering area 8 as shown in FIG. 2(a). However, in the case of defective soldering, the surface has many irregularities and does not have a mirror surface, as shown in FIG. 3(b). Therefore, when the video camera 4 captures an image, a large number of small and complicated areas 9 are captured in the soldering area 8 as shown in FIG. 2(b).

From the above facts, it is possible to determine whether a soldering part is good or bad by comparing the number of bright areas with the number of standard bright areas.

The present invention focuses on the above principle and optically inspects the quality of solder. The operation will be explained below.

In FIG. 1, a ring-shaped illumination device 3 is placed so as to illuminate the electronic component 2 uniformly. And a ring-shaped lighting device 3
The printed circuit board 1 on which the electronic component 2 is mounted is imaged by the video camera 4 while being illuminated by the video camera 4.

Then, the obtained captured image signal is input to the image binarization circuit 5. This image binarization circuit 5 performs analog/digital conversion on the image signal in order to easily divide the image signal into regions, and further binarizes the image signal using luminance values.

Next, the binarized image signal is input to the area extraction circuit 6. This region extracting circuit 6 collects pixels corresponding to the bright portions of the binarized image signal into the same region, including pixels located vertically and horizontally.

Then, the number of bright areas that cannot be grouped together as the same area is counted. FIG. 4 schematically shows a binary image signal. For example, in Figure 4, 10.11
．． Each of the 12 areas is an independent area, and the number of areas among these is 3.

Then, the number of bright areas that cannot be grouped together as the same area is input to the determination circuit 7. This determination circuit 7 compares the number of bright areas obtained from the area extracting circuit 6 with the number of bright areas with good soldering, which serves as a reference sampled and stored in advance. When the number of bright areas obtained by the area extraction circuit 6 is larger than the number of reference bright areas, it is determined to be defective, and when it is smaller, it is determined to be good.

As described above, with a simple device and simple calculations, inspection of soldering parts, which until now had to be done visually, can be performed automatically and at high speed.

In the above embodiment, the ring-shaped illumination device 3 is used as the illumination means, but any other illumination device may be used as long as it has a sufficient amount of light for the video camera 4 to capture an image.

Further, although the image binarization circuit 5 performs analog/digital conversion and then binarizes the image, it is also possible to binarize the image by determining a certain level while keeping the analog quantity.

In addition, when the bright area pixels are grouped together as a region in the region extraction circuit 6, the four neighboring pixels on the top, bottom, left and right sides are grouped together as the same region, but the eight neighboring pixels including the top left, top right, bottom left, and bottom right are also considered as the same region. You can also put them together. In this case, for example in Figure 4, 10.11 are the same area, and the number of areas is 2.
becomes.

Detailed Description of the Invention As described in the present invention, the soldering part is illuminated and imaged, and the number of bright areas formed in the soldering part is counted to judge whether it is good or bad. It is possible to easily inspect whether parts are good or bad. Furthermore, since the configuration of the device is simple and determination of pass/fail requires simple calculations, it can be easily introduced. According to the present invention, the inspection of soldering parts, which has hitherto relied on visual inspection by an operator, can be automated at high speed and reliably.

[Brief explanation of the drawing]

Fig. 1 is a block wiring diagram of a board inspection device according to an embodiment of the present invention, Fig. 2 is a schematic diagram of a part with good soldering and a part with bad soldering, taken from directly above. FIG. 4 is a schematic diagram of a cross-section of a section showing good soldering and a section showing poor soldering, and FIG. 4 is a schematic diagram of binary image data. DESCRIPTION OF SYMBOLS 1... Printed circuit board, 2... Electronic component, 3... Ring-shaped lighting device, 4... Video camera, 5... Image binarization circuit, 6... Area extraction circuit, 7... ... Judgment circuit, 8... Soldering part, 9... Bright area, 10.11
．． 12... area. Name of agent: Patent attorney Satoshi Nakao and one other person Figure 3 (b) Figure 2 (o)

Claims (1)

[Claims] An illumination means for illuminating a printed circuit board to which electronic components or the like are soldered; a video camera for capturing an image of the printed circuit board; and an image binarization circuit for converting an image signal captured by the video camera into a binary image signal. , an area extraction circuit that counts the number of bright areas in a portion corresponding to the soldering part using the image signal binarized by the image binarization circuit; and an area extraction circuit that counts the number of areas obtained by the area extraction circuit. A board inspection device comprising a determination circuit that determines whether a soldered part is good or bad by comparing it with a reference number of areas.