JPH0672776B2 - Inspection device for mounted printed circuit boards - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device for a mounted printed circuit board, and in particular, it detects a positional deviation of a mounted component using a narrowed beam spot, a solder defect, a solder bridge, etc. It is an inspection.

2. Description of the Related Art Conventionally, there is a method using a multi-slit light and a camera as an apparatus for inspecting a component position shift, a defective product, a solder defect, a solder bridge, etc. of a mounted printed circuit board.

Hereinafter, description will be given with reference to the drawings. 5 in FIG.
Reference numerals 5 and 56 denote irradiation devices for irradiating slit light, 54 denotes a camera, and 57 denotes a mounted printed circuit board. The two slit lights are radiated onto the mounted printed circuit board 57 from diagonally above so that their optical axes are orthogonal to each other.
Observing with, you can measure the height of the mounted components by the principle of triangulation. At this time, by alternately irradiating the multi-slit irradiation devices 55 and 56, it is possible to know the component position in the X and Y directions (see FIG. 6).

SUMMARY OF THE INVENTION However, with the above-mentioned configuration, although it is possible to measure the position of the mounted component before soldering, it is difficult to accurately inspect the solder surface after the soldering process. Because the solder surface is close to the mirror surface, the reflected light may be too strong and the camera may be saturated, or the reflected light may be too weak to detect depending on the positional relationship between the solder surface and the camera. Because.

Means for Solving the Problems An inspection device for a printed circuit board already mounted in the present description includes a rotating body driven to rotate, a means for moving a printed circuit board to be inspected relative to the rotating body, and the rotating body. Are located on substantially the same circumference centered on the center of rotation of the printed circuit board, and each of the printed circuit boards is irradiated with a beam spot in a direction substantially perpendicular to the printed circuit board. A plurality of beam spot generating means arranged on the rotating body so as to scan, and a plurality of first spots radially arranged on the rotating body around each of the beam spots and receiving reflected light from the printed circuit board. And a second photoelectric conversion means for measuring the energy of reflected light along the optical axis of the beam spot.

Action According to the above configuration, since the plurality of first photoelectric conversion means for receiving the reflected light of the beam spot are arranged around the beam spot, even if the reflected light changes depending on the orientation of the solder surface, it is possible to cope with it. Since the reflected light can be received by the reflected light, the height and brightness of the solder surface can be measured, and the quality of the mounted printed circuit board can be judged by comparing with the correct solder shape registered in advance. it can. However, since the solder surface has various shapes, the shape may not be properly taken depending on the inclination of the solder surface. Because, in the first photoelectric conversion means,
As shown in the figure, the semiconductor position detection element (PS
D), that is, having a certain predetermined length, the outputs of a plurality of (two) output terminals relatively change according to the position of the light receiving point, and the position of the light spot with the ratio of each output, In other words, when using a device that can measure the distance and measure the brightness with the sum of each output, the amount of light entering the first photoelectric conversion means becomes small when the inclination of the solder surface is steep, and the PSD
If it falls below the allowable range of, the correct height may not be obtained even if the PSD output ratio is measured. In such a case, in this case, the solder surface can be measured by using the second photoelectric conversion means. That is, the second photoelectric conversion means,
Since the amount of reflected light is in the direction along the irradiation beam, the amount of reflected light from the surface perpendicular to the irradiation beam spot is very large, but the amount of reflected light from the surface oblique to the irradiation beam is small. In the mounted printed circuit board, if there is solder at the place where solder should be attached, the output from the second photoelectric conversion means is small because the general solder surface is inclined, but if solder is not attached, the second The output from the photoelectric conversion means becomes large. Thereby, even if the shape of the solder surface is not clear by the first photoelectric conversion means, the inclination of the solder surface can be predicted to some extent by the second photoelectric conversion means. Furthermore, when there is no solder, and when the inclination of the solder is extremely gentle, that is,
Even when the solder portion is defective, it can be extracted by the second photoelectric conversion means.

Embodiment Hereinafter, a mounted printed circuit board inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a unit inspection device in which a beam spot projecting optical system and a light receiving optical system group, that is, a first photoelectric conversion element group and a second photoelectric conversion element are integrated. 1 is
For example, an optical system for projecting a beam spot using a laser beam, 2, 4, 6, 8 receives reflected light from the reflecting surface of the beam spot, and obtains the height and brightness information of the reflecting surface. A first photoelectric conversion element group such as a semiconductor position detection element (hereinafter referred to as PSD) arranged around the spot. This PSD has a predetermined length, and the output of multiple output terminals changes relative to the position of the light spot on the PSD.A CCD line sensor or the like can also be used for this. is there.

As shown in FIG. 5, 3,5,7,9 are lenses or lenses for forming the reflected beams from the mounted printed circuit board on the PSDs 2, 4, 6, 8 for triangulation, respectively. It is a group.

Reference numeral 10 denotes a half mirror, which guides the reflected light along the optical axis of the beam spot to the second photoelectric conversion means 11 via a lens or a lens group.

FIG. 2 shows another unit inspection device in which the first photoelectric conversion element group and the second photoelectric conversion element, which are the optical system for projecting a beam spot and the optical system for receiving light, are integrated as in FIG. 3 is a perspective view of the embodiment of FIG. However, as a means for guiding the reflected light along the beam spot to the second photoelectric conversion means 11, a perforated mirror 12 is used instead of the half mirror 10 in FIG.

FIG. 3 is a perspective view of the entire inspection device. 17,18,19,20
Is a unit inspection device in which the optical system groups shown in FIG. 1 or 2 are integrated. Reference numeral 16 is a rotary disk that is rotationally driven at a substantially constant speed by a drive source (not shown) such as a motor. 17,18,19,20 are arranged at substantially equal intervals on the same circumference with respect to the center of the rotating disk 16, and as the rotating disk 16 rotates, the beam spots sequentially scan the mounted printed circuit board 14. Is configured. Therefore, by sequentially moving the mounted printed circuit board 14 in the y direction of the x, y, z coordinate system shown in FIG. 3, the entire mounted printed circuit board 14 can be scanned by the beam spot. Reference numeral 21 indicates the trajectory currently scanned by the unit inspection device 18, and 22
Indicates the locus scanned by the unit inspection device 19 immediately before.
In FIG. 3, when the unit inspection device 18 has completed scanning, the mounted printed circuit board 14 moves in the y-axis direction by a certain amount, and the movement is completed before the next unit inspection device 17 starts scanning. The inspection can be completed in the minimum time without wasting time.

FIG. 4 shows an electric circuit of this device for obtaining height information, luminance information, etc. by the reflected light from the first photoelectric conversion means and the second photoelectric conversion means. A circuit 23 obtains height information from two current outputs of the first photoelectric conversion element 2 through a divider 52 and obtains brightness information through an operational amplifier 53 from the sum of the two current outputs. 24,25,26 is a detection circuit similar to 23, the first photoelectric conversion element group 4,6,
Connected to 8. In the case of this embodiment, four pieces are used as the first photoelectric conversion element group, and therefore four pieces of height and luminance information are also output for one light spot on which the beam spot hits. Reference numeral 27 is a height information selection circuit for obtaining one height information from four pieces of height information. As a selection method, for example, there is a method of taking four averages. 28, like 27, is a brightness selection circuit for obtaining one brightness information from four brightness information. As a selection method, there is a method of taking the maximum level, for example. Reference numeral 31 is a brightness generation circuit which is connected to the second photoelectric conversion means 11 to obtain brightness information and A / D convert the output.
The outputs of the two selection circuits 27 and 28 and the luminance generation circuit 31 are sent to the RAM 29 connected to the bus of the CPU 30. The CPU 30 compares the height and luminance information read from the RAM 29 with the height information and the luminance information of the reference mounted printed circuit board, which is a reference stored in advance, to determine the printed circuit board of the tested mounted circuit board. Determine pass / fail. At this time,
By using the output information of the second photoelectric conversion means stored in the RAM 29, it is possible to more accurately determine whether the surface shape is expected in advance. The output information of the second photoelectric conversion means, especially in the shape of the solder surface, the amount of reflected light becomes very small, or becomes very large, and the dynamic range of the PSD used in the first photoelectric conversion means. When it exceeds, the height is not recognized correctly, which is very effective.

EFFECTS OF THE INVENTION As described above, according to the present invention, the mounted printing substrate is irradiated with the beam spot substantially vertically, and the first and second photoelectric conversion element groups that are the light receiving system are arranged around the optical axis. By integrally scanning the irradiation and light receiving optical system groups, it has become possible to satisfactorily perform the inspection of the solder surface, which was difficult with the conventional inspection machine.

[Brief description of drawings]

1 and 2 are perspective views of a unit of an inspection apparatus in which a beam spot projecting optical system and a light receiving optical system are integrated in an embodiment of the printed circuit board inspecting method of the present invention.
FIG. 4 is a perspective view showing a main part of the embodiment, FIG. 4 is a block diagram of an electric circuit of the inspection machine, and FIG. 5 is a view showing a principle of triangulation used in the first photoelectric conversion means. FIG. 6 is a perspective view of a conventional printed circuit board inspection device. 1 …… beam spot irradiation optical system, 2,4,6,8 …… first photoelectric conversion element, 3,5,7,9,13 …… lens, 10 …… half mirror, 11 …… second Photoelectric conversion element group, 12 …… Perforated mirror, 14 …… Inspected substrate, 16 …… Rotating disk, 17,18,19,2
0 …… One unit inspection device with integrated optical system group, 23,
24,25,26 …… Height / luminance calculation circuit, 27 …… Height information selection circuit, 28 …… Brightness information selection circuit, 31 …… Brightness generation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eiji Okuda 2-10 No. 2 Kotobukicho, Takamatsu-shi, Kagawa Matsushita Electronics Industry Co., Ltd. (72) Hideyuki Ueoka 2-2 Kotobukicho, Takamatsu-shi, Kagawa No. 10 within Matsushita Electronics Industry Co., Ltd. (56) Reference JP-A 1-320417 (JP, A) JP-A 2-187615 (JP, A) JP-A 62-235511 (JP, A) JP-A 56-67815 (JP, A) JP 62-2114 (JP, A)

Claims (1)

[Claims] 1. A rotary body which is rotationally driven, a means for moving a printed circuit board to be inspected relative to the rotary body, and a position on substantially the same circumference around a rotation center of the rotary body. A plurality of beams arranged on the rotator so as to irradiate beam spots on the printed circuit board in a direction substantially perpendicular to the printed circuit board, and the beam spots sequentially scan the printed circuit board as the rotator rotates. Spot generating means, a plurality of first photoelectric conversion means radially arranged around each of the beam spots on the rotating body and receiving reflected light from the printed circuit board, and along the optical axis of the beam spots. And a second photoelectric conversion means for measuring the energy of reflected light.