JPH0240502A - Method for checking mounted part - Google Patents

Abstract

PURPOSE:To make it possible to perform excellent mounting check for any kind of board by computing a contact area between a land image and an electrode image from computed electrode position data and corrected land position data. CONSTITUTION:A printed board 1 on which chip parts to be checked 10 are mounted is placed on a positioning device 2. The part mounting surface of the board is picked up with a color camera 3. The image data of the part mounting surface of the board which are converted in the camera 3 are once stored in a color image memory 5. The image is processed in a judging part 6. Said processing is performed at an image region unit in each checking window (a) in the part mounting surface of the board which is picked up with the camera. The position of a land image in the checking window (a) is computed from the image data. The land position data are corrected in correspondence with the result. Electrode position data which impart the electrode position of the electrode image of the part are computed from the image data. A contact area between the land image and the electrode image is computed from the electrode position data and the corrected land position data. The quality of the mounting of the part is judged from the contact area.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a mounted component inspection method for inspecting board mounting of electronic components.

<Conventional technology> The density of component mounting on printed circuit boards has become extremely high as electronic products have become smaller and more sophisticated in recent years.
BACKGROUND OF THE INVENTION Mounted component inspection apparatuses that inspect board mounting of electronic components such as chip components are becoming increasingly important.

The mounted component inspection device is configured such that the quality of the board mounting of the component is inspected by photographing the board component mounting surface with a CCD camera or the like and comparing this photographed image with a standard pattern image stored in advance. It becomes.

Next, a conventional mounted component inspection method employed in such a mounted component inspection apparatus will be described in detail.

Image data of the board component mounting surface converted by a CCD camera, etc. is captured into an image memory, and then sequentially read out and given to a microcomputer, where coordinate data in an absolute coordinate system is calculated based on reference points provided on the printed board. is converted to The image data converted to coordinate data is then compared with data related to the standard pattern image stored in another memory, and the difference between the photographed image and the standard pattern image is determined. It is designed to be judged as good or bad. Note that the reference point mentioned above is a reference hole provided on a printed circuit board, a patterned fiducial mark, or the like.

<Problems to be Solved by the Invention> However, according to the conventional method described above, it may not be possible to perform a good mounting inspection depending on the type of printed circuit board. In other words, if the printed circuit board is likely to expand, contract, or warp due to positioning errors, temperature, humidity, etc., even if the components are mounted normally, the photographed image and the standard pattern that should be used as a reference cannot be used. Since the images do not match, there is a drawback that it may be erroneously determined as a defective component mounting. This misjudgment also occurs due to dimensional errors in manufacturing the printed circuit board.

Moreover, this poses a particularly serious problem when inspecting flexible substrates, which have recently become popular.

By the way, the original purpose of mounting inspection is to check whether the land on the board and the electrode of the component are connected with a predetermined contact area, and whether the mounted component can perform its normal function. be. However, the conventional method described above does not take into account the contact area between the electrode and the land of each different component, and makes a uniform determination of pass/fail for all components, so the inspection accuracy is inherently low. This is low, and there is a risk of misjudgment in some cases.

Both of these drawbacks become very serious problems when the land and the mounted components become smaller as the component mounting density on the board increases.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide a method for inspecting mounted components that can perform mounting inspection on individual components and that can perform highly accurate mounting inspection on any type of board. shall be.

<Means for Solving the Problems> In the mounted component inspection method according to the present invention, land position data of a master board is prepared in advance, and based on the photographed image data of the board component mounting surface and the land position data. In a method of inspecting the mounting of a component in units of image areas of an inspection window, the position of a land image in the inspection window is calculated from the image data, the land position data is corrected according to the calculation result, and the position of the land image of the component is Calculating electrode position data giving the electrode position of the electrode image from the image data, calculating a contact area between the land image and the electrode image based on the calculated electrode position data and corrected land position data, Based on this calculation result, the quality of the mounting of the component is determined.

<Embodiment> An embodiment of the mounted component inspection method according to the present invention will be described above with reference to the drawings. Figure 1 is a schematic diagram of a four-installed component inspection device that employs the proposed component inspection method, Figure 2 is a front view of the board component mounting surface of the board to explain the inspection window, and Figure 3 is the inspection window. FIG. 4 is an explanatory diagram showing an image of the master board within the area of the inspection window, and FIG. 4 is an explanatory diagram showing the image of the printed circuit board within the area of the inspection window.

First, an outline of a mounted component inspection apparatus employing the mounted component inspection method according to the present invention will be explained with reference to FIG.

A printed circuit board 1 on which a chip component 10 to be inspected is mounted is placed on a positioning device 2, and in this state, a color camera 3 disposed above is configured to photograph the surface on which the circuit board component is mounted. . The image data of the board component mounting surface converted by the color camera 3 is once taken into the color image memory 5, read and written by the determination section 6, which is a microcomputer, and image processing is performed. This image processing is performed for each image area of the inspection window a shown in FIG. 2 among the photographed board component mounting surfaces. As a result of this image processing, the quality of the mounting inspection of the chip components 10 within the areas of two adjacent inspection windows a is performed. Incidentally, numeral 4 shown in FIG. 1 is a ring illumination disposed in front of the color camera 3, so that the board component mounting surface of the printed circuit board 1 is uniformly illuminated.

Next, a process for capturing land position data etc. necessary as pre-processing for mounting inspection will be described.

This land position data is the position information of the land 20'' patterned on the master board of the printed circuit board l, and is stored in a predetermined memory through the following processing.

That is, the board component mounting surface of the master board (not shown) is photographed with a color camera 3, and land 20゜ is selected from this photographed image.
Only pixels having the same color component are extracted, and the coordinate values of the extracted pixels are stored in the memory of the determination unit 6 as land position data.

By the way, inside the inspection window a, as shown in FIG. 3, a total of three position correction windows bx and by are provided. The position correction window bx and the position correction window bV are arranged perpendicularly to each other, and the distances on the image from the edge of the inspection window a to the land 20° are respectively determined and stored in memory as land position parameters. It is stored in. In other words, the position of the image of the land 20' (or the land 20) in the inspection window is determined by the position correction window bx and the position correction window bv. Note that these position correction windows bX, bY are as follows:
It may be provided at any number of locations as long as it can reach the land 20'' from the end of the inspection window a, and in this case there is an advantage that it will be resistant to noise if the output is averaged.

Hereinafter, the process by which the determining section 6 performs a mounting inspection of the chip component a based on the image data stored in the image memory 5 will be described with reference to FIG.

First, as shown in FIG. 4, all pixels having the same color component as the land 20 are extracted from the image area of the inspection window a, and the coordinate values of the extracted pixels are stored in the memory as photographing land position data. put.

Then, using the position correction windows bX, b, the distances on the image from the end of the inspection window a to the end of the land 20 on the printed circuit board 1 are respectively determined and stored in the memory as photographing land position parameters.

After that, the photographing land position data, photographing land position parameters and land position data respectively read out from the memory,
By comparing the land position parameters, the amount of positional deviation between the land 20' on the master board and the land 20 on the printed circuit board l is calculated, and the land position data is corrected according to this amount of deviation. The corrected land position data is then stored in the memory as new corrected land position data.

In addition, the chip component IO is inspected from within the image area of inspection window a.
Extract all pixels having the same color component as the electrode 11,
The coordinate values of the extracted pixels are stored in the memory as electrode position data. Then, the corrected land position data is read out from the memory along with the electrode position data, and based on this, the number of pixels having common coordinate values is calculated. Then, by multiplying the calculated number of pixels by a preset area value for one pixel, the contact area of the image portion of the contact portion 111 between the electrode 11 and the land 20 is calculated.

The contact area calculated in this way is compared with a preset allowable area value of the contact portion 111, and if the contact area exceeds the allowable area value, it is determined that the chip component 10 is well mounted. On the other hand, if the contact area does not exceed the allowable area value, it is determined that the chip component 10 is defectively mounted. Note that the above-mentioned allowable area value is a value that differs depending on the type of component to be inspected.

Therefore, in the case of this embodiment, the printed circuit board 1 may expand or contract or warp due to positioning errors of the printed circuit board 1 by the positioning device or external factors such as temperature and humidity, or the printed circuit board 1 may have irregular dimensions during processing. Even if there is an error, the land position data that should serve as the inspection standard is corrected, eliminating erroneous judgments in mounting inspection. Therefore,
All kinds of printed circuit boards can be inspected.

In addition, individual chip components 1 mounted on the printed circuit board 1
0, and the contact area between the electrode 11 of the chip component 10 and the land 20 is taken into consideration in the determination of the mounting inspection, so the accuracy of the mounting inspection of the chip component 10 is significantly improved. I will do it. Therefore, it is of great significance especially in a situation where the lands 20 of the printed circuit board 1 and the chip components 10 are becoming smaller.

Note that the mounted component inspection method according to the present invention can be used, for example, if the difference in brightness between the land and the electrode of the component can be sufficiently identified.
Of course, the present invention can be applied to a mounted component inspection apparatus using a black and white camera, and can also be applied even if the number of electrodes of the component is two or more.

<Effects of the Invention> Hereinafter, in the case of the present mounted component inspection method, even if the board has expansion/contraction, warpage, or dimensional errors due to processing, the land position data of the master board, which is the reference for inspection, is corrected. Therefore, there are no erroneous judgments during mounting inspection, and good mounting inspection can be performed on any type of board. Moreover, in addition to being able to perform mounting inspection on individual parts, it is also possible to judge the quality of mounting inspection.
Since the contact area between the electrode and the land is taken into account, inspection accuracy is significantly improved. Therefore, it is of great significance in a situation where the mounting density of components on boards increases and the lands, components, etc. become smaller.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining an embodiment of the mounted component inspection method according to the present invention, and FIG. 1 is a schematic diagram of a mounted component inspection apparatus that employs the mounted component inspection method of the present invention. , FIG. 2 is a front view showing the board component mounting surface of the board for explaining the inspection window, FIG. 3 is an explanatory diagram showing an image of the master board within the area of the inspection window, and FIG.
The figure is an explanatory diagram showing an image of a printed circuit board within the area of the inspection window. l...Printed circuit board 10...chip component 11...electrode 20...land a...inspection window patent applicant Sharp Corporation

Claims (1)

[Claims] (1) Land position data of the master board is prepared in advance, and mounting components are inspected for each image area of the inspection window based on the photographed image data of the board component mounting surface and the land position data. In the inspection method, the position of a land image in the inspection window is calculated from the image data, the land position data is corrected according to the calculation result, and the electrode position data giving the electrode position of the electrode image of the part is added to the image. The contact area between the land image and the electrode image is calculated based on the calculated electrode position data and the corrected land position data, and the quality of the mounting of the component is determined according to the calculation result. A mounted component inspection method characterized by determining.