JPH02187616A - Inspection device for mounted printed board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a device for inspecting mounted printed circuit boards, and in particular uses a narrow beam spot to detect misalignment of mounted components, solder defects, and solder defects. It is intended to inspect bridges, etc.

Conventional technology Conventionally, misalignment of components on mounted printed circuit boards, missing parts, etc.
There is a method that uses a multi-slit light and a camera as a device for automatically inspecting defects such as defects and defects.

This will be explained below with reference to the drawings. In Figure 5,
55 and 56 are irradiation devices that irradiate the slide light, 54 is a camera, and 67 is a mounted printed circuit board. By irradiating the mounted printed circuit board 57 with two slit lights obliquely from above so that their optical axes are perpendicular to each other and observing it from above with the camera 54, the height of the mounted component can be measured using the principle of triangulation. At this time, by alternately irradiating with the multi-slit irradiation device 55 and 56,
”+V force direction (see Figure 5)) can be found.

Problems to be Solved by the Invention However, with the above configuration, although it is possible to measure the position of the mounted components before soldering, it is difficult to accurately inspect the soldering process after the soldering process. This is because the solder surface is close to a mirror surface, so depending on the orientation of the solder surface and the position of the camera, the reflected light may be too strong and saturate the camera, or conversely, the reflected light may be too weak to be detected. This is because

Means for Solving the Problems The installed printed circuit board inspection apparatus of the present invention comprises a rotating body that is rotationally driven, a means for moving the printed circuit board to be inspected relative to the rotating body, and a means for moving the printed circuit board to be inspected relative to the rotating body. The beam spots are located on substantially the same circumference centered on the rotation center of the body, and each beam spot is irradiated from a direction substantially perpendicular to the printed circuit board, and the beam spot sequentially scans the printed circuit board as the rotating body rotates. a plurality of beam spot generating means disposed on the rotary body so as to condense the reflected light from the printed circuit board near the central axis of each beam spot; , a plurality of photoelectric conversion means arranged near the central axis of the beam spot so as to be parallel to each other and the central axis thereof to receive the light focused by the concave mirror;
It is characterized by the use of a photoelectric conversion means that outputs either or both of an output according to the light receiving position and an output according to the received light energy as the photoelectric conversion means.

Effect: According to the above configuration, beam spots and/) reflected light in all directions and all inclinations can be focused near the photoelectric conversion means, so no matter how the direction or inclination of the solder surface changes, the trench is However, no matter how the diffusion characteristics of the reflected light change, it is possible to reduce the fluctuations in the inspection results, and to perform a good inspection by comparing with the correct unevenness information of the printed circuit board that is known in advance. I can do it.

Embodiment Hereinafter, an inspection apparatus for a mounted printed circuit board according to an embodiment of the present invention will be explained with reference to the drawings. FIG. 2 is a sectional view taken along the line j)--input in FIG. 1. 1 is v
For example, an optical system for projecting a beam spot using a laser,
Reference numeral 2 denotes a concave mirror made of a paraboloid or the like for condensing the reflected light from the reflecting surface of the beam spot near the optical axis of the beam spot, and the optical axis of the beam spot and the central axis of the concave mirror 2 almost coincide with each other. It is arranged like this. 3, 4, 5.6 are photoelectric conversion elements such as semiconductor device detection elements for receiving the reflected light from the concave mirror and obtaining information on the receiving position and brightness of the reflected light. This photoelectric conversion element 3.4
, 15 and 6 have a certain predetermined length, are arranged close to the optical axis of the beam spot and parallel to the optical axis, and have their longitudinal centers aligned with the concave mirror 2.
The outputs of the plurality of output terminals change relatively depending on the irradiation position of the beam spot in the longitudinal direction of the photoelectric conversion element. It is also possible to use a COD line sensor or the like.

FIG. 3 is a perspective view of the entire inspection device. 13°14.1
Reference numerals t5 and 16 are unit inspection devices that form the optical system group shown in FIG. Reference numeral 12 denotes a rotating disk that is driven to rotate at a substantially constant speed by a drive source (not shown) such as a motor. The unit inspection devices 13, 14, 15, 16 inspect the rotating disk 1 at equal intervals on the same circumference with respect to the center of the rotating disk 12.
The beam spot is arranged so as to sequentially scan the mounted printed circuit board 10 with 20 rotations.

With these configurations, the four mounted printed circuit boards 10 can be arranged as shown in FIG. By sequentially moving in the y direction of the Z coordinate system, it becomes possible to scan the entire mounted printed circuit board 10 with the beam spot. Reference numeral 17 indicates a trajectory currently being scanned by the unit inspection device 15, and 18 indicates a trajectory scanned by the unit inspection device 14 immediately before. Therefore, there is no wasted time and the inspection can be completed in the minimum amount of time.

FIG. 4 shows an electric circuit of this device for obtaining height and brightness information by calculating two current outputs whose values change relatively depending on the irradiation position from the photoelectric conversion elements 3, 4, and 5.6. It shows. 69 is a height and brightness information detection circuit which obtains height information from the two current outputs of the photoelectric conversion element 3 through a divider 67, and also obtains brightness information from the two current outputs through an operational amplifier 68. Ru. 60,6
1.degree. 62 is also a detection circuit similar to the front height and brightness information detection circuit 59, and is connected to the photoelectric conversion elements 4, 6, and 6. In this case, since four photoelectric conversion elements are used, four pieces of height and brightness information are output for one light spot. 63 is a height information selection circuit that obtains one piece of height information from four pieces of height information, and as a selection method, for example, the maximum level and the minimum level of the four pieces are excluded and the average of the remaining two is filled. There is a way. Reference numeral 64 denotes a brightness information selection circuit that obtains one piece of brightness information from four pieces of brightness information, and a selection method thereof includes, for example, a method of selecting the maximum level among the four pieces of brightness information. In this way, the selection circuits 63 and 64 are provided for the purpose of: saving the RAM 65 and reducing the load on the CPUE by adding preprocessing. The outputs of the two selection circuits 63, 64 are sent to the flAM 65, which is connected to the bus of cp'oee. In the CPUee,
The height and brightness information read from the RA'btr e 5 is compared with the height and brightness information obtained from the standard mounted printed circuit board and stored in advance, and the mounted printed circuit board to be inspected is determined. Determine the quality of the board.

As described above, in this embodiment, the mounted printed circuit board to be inspected is irradiated with a beam spot perpendicularly, and the beam spot is moved together with the photoelectric conversion elements arranged around the mounted printed circuit board. Since this method measures changes in height and brightness at each point, each point on the mounted printed circuit board is measured under the same conditions, and good inspection can be expected. However, since the reflected light from the mounted printed circuit board is condensed by the concave mirror onto the photoelectric conversion element placed near the optical axis of the beam spot, the direction and inclination of the solder surface changes. Therefore, even if the reflected light from the mounted printed circuit board has various diffusion characteristics, it is possible to reduce the variation in the inspection results caused by this.

Effects of the Invention As described above, according to the present invention, a beam spot is irradiated almost perpendicularly to a mounted printed circuit board, a plurality of concave mirrors and photoelectric conversion elements are arranged in place of the optical axis, and the irradiation and light receiving optical system By working together to measure and scan the mounted printed circuit board, it is now possible to successfully inspect the solder surface, which was difficult to do with conventional inspection machines.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a unit inspection device in which a beam spot projecting optical system and a light receiving optical system are integrated in one embodiment of the mounted printed circuit board inspection device of the present invention, and FIG.
Figure 3 is a perspective view showing the main parts of the same embodiment, Figure 4 is a block diagram of the electric circuit of the same embodiment, and Figure 5 is a conventional printed circuit board inspection device. FIG. 1... Optical system for beam spot projection, 2...
...Concave mirror, 3,4...Photoelectric conversion element, 1o.
... Test tube printed circuit board, 11 ... Beam spot, 12 ... Rotating disk, 13, 14,
15.16...mark/unit inspection device, 54...
Camera, 56.66... Slit light projection irradiation device, 59, 60, 61.62... Height and brightness detection circuit, 63... Height information selection circuit, 64
...Brightness information selection circuit, 65...RA
M, 66...CPU

Claims (1)

[Claims] A rotary body that is rotationally driven, a means for moving a printed circuit board to be inspected relative to the rotary body, and a means for moving a printed circuit board to be inspected relative to the rotary body; a plurality of beam spot generating means disposed on the rotating body so as to irradiate beam spots from a direction substantially perpendicular to the rotating body so that the beam spots sequentially scan the printed circuit board as the rotating body rotates; a concave mirror disposed on the printed circuit board for condensing the reflected light from the printed circuit board near the center axis of each beam spot; and a concave mirror disposed near the center axis of the beam spot for receiving the light focused by the concave mirror. The photoelectric conversion means includes a plurality of photoelectric conversion means arranged parallel to each other and the central axis, and the photoelectric conversion means has an output according to a light receiving position;
An inspection device for a mounted printed circuit board, characterized in that it uses a photoelectric conversion means that outputs either or both of outputs according to received light energy.