JPH03245548A - Soldering inspecting device - Google Patents

Abstract

PURPOSE:To inspect correctly a soldered state without being affected by the installation positions of mounting components by a method wherein the installation positions of the electronic components are detected from the discontinuous parts of slit patterns, which are irradiated by a slit light source, on a printed board and the position of an inspection window is corrected. CONSTITUTION:A pair of slit light sources 6 are controlled by a slit light source controller 8 to emit light in an installation position inspecting mode, and slit patterns 13x and 13y in X and Y axial directions are formed on a printed board 1. These patterns seen from directly over the patterns are discontinuous. A CPU 10 reads out image data stored in an image memory 11, detects discontinuous parts of the patterns 13x and 13y in respect to the X and Y axial directions, finds the forms of the outer contours of electronic components 2 from the result of the detection and detects the installation positions of the components 2 from the central positions of the forms. The CPU reads out data on the installation positions, which is used as a reference on the components 2, from a CAD database 12 and compares the data with reference data. The CPU corrects the positions of the components 2 on the basis of information on the positional deviation of the components 2 and a soldered state is inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a soldering inspection device for inspecting the soldering condition of electronic components mounted on a printed circuit board.

<Prior Art> When electronic components such as ICs, capacitors, and resistors are incorporated into various electronic devices, the incorporation is usually performed by mounting the electronic components on a printed circuit board provided with wiring. It goes without saying that in order for an electronic device with built-in electronic components to operate properly, the electronic components built into the electronic device must be of good quality, but even if each electronic component is of good quality, It is necessary that the solder is correctly mounted on the printed circuit board at a predetermined position, and that the solder is attached to the proper location after soldering. Therefore, electronic components mounted on printed circuit boards are inspected for their mounting positions and soldering conditions.

Conventionally, two methods have been used to inspect the mounting position and soldering condition of electronic components mounted on a printed circuit board: visual inspection by an inspector and automatic inspection using an inspection device. However, during visual inspection by inspectors,
Not only can oversights and inspection errors occur due to fatigue, but
The basic problem is that variations in inspection accuracy due to individual differences are unavoidable, and above all, it is inefficient work that places a heavy burden on inspectors. Therefore, the introduction of automatic inspection using inspection equipment has recently been actively promoted, and the inspection equipment can set inspection windows for electronic components on printed circuit boards and their solder joints. It has become.

<Problems to be Solved by the Invention> However, conventional automatic inspection devices are divided into a component position inspection device that inspects the mounting position of electronic components, and a soldering inspection device that inspects the soldering condition. For soldering, inspection equipment does not have a function to inspect the mounting position of electronic components. Further, even in a device in which both are combined, component position inspection and soldering inspection are carried out in separate processes.

Therefore, when inspecting the state of soldering with conventional automatic inspection equipment, if the electronic component to be inspected is mounted in the correct position on the printed circuit board, the inspection window will be correctly placed over the solder joint of the electronic component. There is no problem with the judgment. However, if there is a positional shift in the electronic component to be inspected, there is a problem in that the inspection window does not fit into the solder joint accurately, making it impossible to accurately determine the soldering condition. Particularly in recent years, electronic components have become smaller, their packaging has become more dense, and QFPs have become finer pitched, making it difficult for conventional automatic inspection equipment to cope with the trend.

The present invention was created in view of such circumstances,
The purpose is to provide a soldering inspection device that can accurately inspect the soldering condition without being affected by the mounting position of the mounted component on the printed circuit board.

<Means for Solving the Problems> A soldering inspection apparatus according to the present invention sets an inspection window at a solder joint of an electronic component mounted on a printed circuit board to inspect the soldering condition. The condition inspection device includes a slit light source that irradiates a printed circuit board with slit light from diagonally above, an epi-illumination light source that illuminates the printed circuit board from directly above, and a pattern image of the printed circuit board that is illuminated by these light sources. Processes the image signal of the image pickup means to take an image and the pattern image outputted by the image pickup means, and positions the inspection window based on the mounting position data of the mounted component on the printed circuit board detected from the pattern image when the slit light source is driven. The inspection window whose position has been corrected is equipped with image processing means for detecting the state of soldering from the brightness and darkness of the pattern image when the epi-illumination light source is driven.

<Operation> By driving the slit light source, slit light is projected onto the printed circuit board from diagonally above, thereby forming a slit pattern on the printed circuit board. Since the electronic component has a three-dimensional shape on the printed circuit board, the slit pattern image captured by the imaging means becomes discontinuous at the boundary between the electronic component and the printed circuit board.

Therefore, the mounting position of the electronic component is detected from the discontinuity of the slit pattern on the printed circuit board illuminated by the slit light source. Data regarding the mounting position of the electronic component is used to correct the position of the inspection window.

When the epi-illumination light source is driven, the printed circuit board is illuminated by a vertically downward light beam. On the surface of electronic components and on the surface of printed circuit boards, the light flux is reflected back to its original direction, whereas at the solder joints of electronic components, the surface of the solder layer is inclined, so the light flux is reflected back to its original direction. reflected in other directions. Therefore, the pattern image of the solder joint portion imaged by the imaging means becomes dark, and becomes bright if there is no solder in that portion. Therefore, the presence or absence of solder can be detected from the brightness and darkness of the pattern image.

<Embodiment> Hereinafter, an embodiment of the soldering inspection apparatus according to the present invention will be described with reference to the drawings. Figure 1 is a schematic configuration diagram of the soldering inspection equipment, Figure 2 is a plan view showing the projection state of the slit light on the printed circuit board, and Figures 3 and 4 are the settings of the inspection window on the printed circuit board. The plan view and FIGS. 5 and 6 are side views for explaining the principle of inspecting soldering using epi-illumination.

As shown in FIG. 1, the soldering inspection apparatus is equipped with a CCD camera 3 serving as an image capturing means for capturing a pattern image of a printed circuit board 1. The CCD camera 3 is configured to image the printed circuit board 1 placed on the XY stage 4 from directly above. The XY stage 4 is controlled through the stage controller 5 according to instructions from the CPU10. A large number of electronic components 2 are mounted on the printed circuit board 1, and their mounting positions and soldering conditions are subject to inspection.

A pair of slit light sources 6 and 6 are arranged around the CCD camera 3. Further, an annular epi-illumination light source 7 is arranged around the lens portion of the CCD camera 3.

The slit light sources 6 and 6 are controlled by the slit light source controller 8 according to instructions from CPtJlo, and project a plurality of parallel slit lights in the X-axis direction and the Y-axis direction onto the printed circuit board 1 from diagonally above. The epi-illumination light source 8 is controlled by the epi-illumination light source controller 9 according to instructions from the cpuio, and is configured to epi-illuminate the printed circuit board 1 with a vertically downward beam of light from directly above. The CCD camera 3 captures a pattern image formed on the printed circuit board 1 by driving these light sources.

The pattern image of the printed circuit board l captured by the CCD camera 3 is temporarily stored in the image memo January 1. CPU10 is
In addition to performing the above-mentioned light source control, it constitutes an image processing means, and here, based on the image data held in the image memory 11 and the data stored in the CAD database 12, the The mounting position of the electronic component 2 and the presence or absence of soldering are detected and determined. The data stored in the CAD database 12 is design data of the printed circuit board 1 that serves as a standard for inspection, that is, data regarding the mounting position of the electronic component 2, the soldering position, etc.

The soldering inspection device inspects the mounting position of the electronic component 2 mounted on the printed circuit board 1, adjusts the position of the inspection window appropriately based on the inspection result, and then inspects the soldering condition. Execute. The procedure will be explained below.

(1) Mounting position inspection When the mounting position inspection mode is selected on a console outside the diagram, the slit light sources 6 and 6 emit light under the control of the slit light source controller 8, and the second
As shown in the figure, slit patterns 13x and 13y in the X-axis direction and the Y-axis direction are formed. The electronic component 2 mounted on the printed circuit board 1 has a three-dimensional shape, and a line-shaped slit light is projected onto the printed circuit board l from an oblique direction. Therefore, at the boundary between the electronic component 2 and the printed circuit board 1 in the outer part of the electronic component 2, the slit patterns 13x and 13y become discontinuous when viewed from directly above. CPU10 reads out the image data stored in the image memory 11 and creates slit patterns 13x and 1.
3y discontinuous portions are detected in the X-axis direction and the Y-axis direction, the outer shape of the electronic component 2 is determined from the results, and the mounting position of the electronic component 2 is detected from the center position.

When the mounting position of the electronic component 2 is detected by the above method, the CPU 10 reads the standard mounting position data for the electronic component 2 from the CAD data base 12, and compares the standard data with the detected data. . When the electronic component 2 is installed in the correct position, as shown in FIG. . Therefore, the inspection window W remains in this position in preparation for inspection of the soldering condition.

If the electronic component 2 is not installed in the correct position,
As shown in FIG. 4, the inspection window W does not fit into the solder joint of the electronic component 2 accurately.

Therefore, based on the positional deviation information from the standard position of the electronic component 2 that is not installed in the normal position, the CPU10
The position of the inspection window W is corrected so that it accurately covers the solder joint of the electronic component 2, and the soldering state is prepared for inspection.

(2) Soldering Status Inspection When the soldering status inspection mode is selected on the console outside the diagram, the epi-illumination light source 8 is activated under the control of the epi-illumination light source controller 9 based on instructions from the CPU10.

As a result, the printed circuit board 1 is illuminated by a vertically downward light beam. When the printed circuit board 1 is epi-illuminated, if the electronic components 2 on the printed circuit board l are properly soldered, the surface of the solder joint 2a will be inclined, as shown in FIG. In other words, the light is not reflected back to its original direction. Therefore, the solder joint 2a imaged by the CCD camera 3
The pattern image viewed from directly above becomes dark.

If there is no solder in the area where solder should be attached, the light will be reflected back to the original direction at that area, as shown in FIG. Therefore, the pattern image taken by the CCD camera 3 from directly above that portion becomes brighter.

CPUl0 measures the brightness of each inspection window W, and if the measured brightness is below a predetermined value, it is determined as "solder present (good)", otherwise it is determined as "defective without solder".
”.

The above procedure enables automatic inspection of the mounting position and soldering condition of electronic components mounted on a printed circuit board. Moreover, soldering corrects the position of the inspection window during condition inspection based on the mounting position information of the electronic components obtained from the mounting position inspection. Even in today's world where the number of pitches is increasing, highly reliable inspections can be performed at high speed.

<Effects of the Invention> As described above, when the soldering inspection apparatus according to the present invention is used, the condition of the soldering of electronic components mounted on a printed circuit board can be inspected automatically and at high speed. Moreover,
During the inspection, the position of the inspection window is corrected based on the mounting position information of the electronic components obtained from the mounting position inspection using slit light. Even in these days when pitching is becoming more common, we are able to conduct highly reliable inspections.

Furthermore, since general lighting can be used as both the slit light source and the epi-illumination light source, the equipment price is low despite its high precision, and its wide irradiation range makes it possible to use multiple inspection windows within the same field of view. This aspect also helps speed up the inspection.

[Brief explanation of drawings]

1 to 6 are drawings for explaining an embodiment of the soldering inspection device according to the present invention, and FIG. 1 is a schematic diagram of the soldering inspection device, and FIG. 2 is a printout. A plan view showing the projection state of the slit light on the board, Figures 3 and 4 are plan views showing the setting state of the inspection window on the printed circuit board, and Figures 5 and 6 show the inspection of soldering using epi-illumination. FIG. 3 is a side view for explaining the principle. ...Printed circuit board, electronic component, solder joint, imaging means, slit light source, epi-illumination light source No. 11! l Figure 2 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] (1) A soldering condition inspection device that inspects the soldering condition by setting an inspection window on the soldered joints of electronic components mounted on a printed circuit board, with a slit that irradiates the printed circuit board with slit light from diagonally above. a light source, an epi-illumination light source that epi-illuminates the printed circuit board from directly above, an imaging means for capturing a pattern image of the printed circuit board illuminated by these light sources, and an image signal regarding the pattern image output by the imaging means. The position of the inspection window is corrected based on the mounting position data of the mounted components on the printed circuit board detected from the pattern image when the slit light source is activated. 1. A soldering inspection device comprising: an image processing means for detecting a soldering state from brightness and darkness of the soldering inspection device.