JPH0718691B2 - 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 apparatus for a mounted printed circuit board, and in particular, misalignment of parts mounted by using a narrowed beam spot, defective solder, solder bridge, etc. Is to be inspected.

2. Description of the Related Art Conventionally, there is a method using a multi-slit light and a camera as an apparatus for automatically inspecting a positional deviation, a missing item, a solder defect, a solder bridge, etc. of a mounted printed circuit board component.

Hereinafter, description will be given with reference to the drawings. In FIG.
55 and 56 are irradiation devices that respectively irradiate slit light, 54 is a camera, and 57 is a mounted printed circuit board. The two slit lights are radiated onto the mounted printed circuit board 57 obliquely from above so that their optical axes are orthogonal to each other, and when observed by the camera 54 from above, the height of the mounted component can be measured by the principle of triangulation. At this time, the multi-slit irradiation device 55,5
By irradiating 6 alternately, x and y directions (see Fig. 4)
You can know the parts position of.

However, in the above-mentioned configuration, in the case of solder surface inspection, the reflection / diffusion characteristic is close to a mirror surface. Therefore, depending on the orientation of the solder surface and the positional relationship of the camera, the reflected light may be too strong. There is a defect that it may be saturated, or the reflected light may be too weak to be detected. In addition, there is a limit to the observation field of view by the camera, and in some cases, only a part of the inspection target part can be captured within the camera field of view. In such a case, there is a problem that the inspection software becomes complicated because it is necessary to inspect one component with image information of a plurality of fields of view.

Means for Solving the Problems An inspection device for a mounted printed circuit board according to the present invention is provided with a generator for generating a narrowed beam spot on a rotating body,
By rotating the rotator while irradiating the beam spot on the mounted printed circuit board substantially perpendicularly,
The surface of the mounted printed circuit board is scanned with the beam spot, and a change in at least one of the reflection angle and the reflection intensity of the reflected light is sequentially detected by the photoelectric conversion element provided on the rotating body, and the mounted printed substrate The mounted printed circuit board is inspected by measuring at least one of the height of the light spot which is the intersection of the beam spot and the brightness information of the light spot.

Effect According to the above configuration, since the mounted printed board is scanned by the beam spot irradiated from the direction perpendicular to the mounted printed board to be inspected, each point on the mounted printed board is measured under the same condition. As a result, good inspection can be performed. In addition, because multiple photoelectric conversion elements that receive the reflected light of the beam spot are arranged around the beam spot, even if the diffusion characteristics of the reflected light from the mounted printed circuit board change, the inspection result will not change. It can be made small. Also, if the height and brightness information of the mounted printed circuit board is taken into the memory and inspected, the same parts can be handled by the same inspection software, and the inspection software can be easily created.

Embodiment Hereinafter, a mounted printed circuit board automatic 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 an optical system for projecting a beam spot and an optical system group for receiving light are integrated.

1 is an optical system for projecting a beam spot using, for example, a laser, and 2, 4, 6, 8 are for receiving the reflected light from the reflecting surface of the beam spot and for obtaining the height and brightness information of the reflecting surface. It is a photoelectric conversion element such as a semiconductor position detection element (hereinafter referred to as PSD). This PSD has a certain predetermined length, and the outputs of a plurality of output terminals relatively change according to the irradiation position of the beam spot, and it is possible to use a CCD line sensor or the like for this. . 3,5,7,9 are lenses or lens groups for respectively imaging the reflected beam spots from the mounted printed circuit board on the photoelectric conversion elements 2, 4, 6, 8 for performing triangulation. . These photoelectric conversion elements and lenses are arranged around the optical axis of the beam spot 11, and in this embodiment, four sets are arranged at equal intervals on the same circumference centered on the beam spot. The angle θ between the beam spot optical axis and the optical axis of the lens arranged in front of the photoelectric conversion element is preferably 20 to 30 degrees. The reason is that the solder attached to the chip components mounted on the printed circuit board has an inclination of about 45 degrees, and when the angle is larger than 30 degrees, the reflected beam spot light becomes too strong and the photoelectric conversion element saturates. Causes the problem. Also, the angle
If the angle is smaller than 20 degrees, the accuracy is lowered because the height is measured using the principle of triangulation. Further, the smaller the beam spot light, the more accurately the fine irregularities on the surface can be measured. Therefore, in the printed circuit board, most of the measuring objects such as parts are 2 m high.
Since it is within m, it is the intermediate height of the printed circuit board 10.
By setting the minimum point of the beam spot at 1 mm from the surface of, the average accuracy will be maximized. 10 is a mounted printed circuit board, and 11 is a beam spot, which is irradiated almost perpendicularly to the mounted printed circuit board 10.

FIG. 2 is a perspective view of the entire inspection device. 13,14,15,16
Is a unit inspection device in which the optical system groups shown in FIG. 1 are integrated. Reference numeral 12 is a rotary disk that is rotationally driven at a substantially constant speed by a drive source (not shown) such as a motor. The unit inspecting devices 13, 14, 15, 16 scan the mounted printed circuit board 10 sequentially by the beam spots as the rotating disk 12 rotates at equal intervals on the same circumference with respect to the center of the rotating disk 12. Is arranged. Therefore, the mounted printed circuit board 10
By sequentially moving in the y direction of the x, y, z coordinate system shown in FIG. 2, it becomes possible to scan the entire mounted printed circuit board 10 with the beam spot. Reference numeral 17 indicates a locus which is currently scanned by the unit inspection device 14, and 18 indicates a locus scanned by the unit inspection device 15 immediately before. In FIG. 2, when the unit inspection device 14 completes scanning, the mounted printed circuit board 10 moves in the y-axis direction, and the movement ends before the next unit inspection device 13 starts scanning, which is a waste. The inspection can be completed in the minimum time without any time.

FIG. 3 shows an electric circuit of this device for calculating height information and luminance information by calculating two current outputs whose values relatively change depending on the irradiation position from the photoelectric conversion element. 19
Is a height and brightness information detection circuit that obtains height information from two current outputs of the photoelectric conversion element 2 through a divider 52 and brightness information through an operational amplifier 53 from the sum of the two current outputs. . 20,21,22 is also a detection circuit similar to the height and luminance information detection circuit 19, photoelectric conversion elements 4,6,8
It is connected to the. In this case, since four photoelectric conversion elements are used, the height and brightness information is 4 for one light spot.
Are output individually. Reference numeral 23 is a height information selection circuit that obtains one height information from four height information. As a selection method, for example, the method of taking the average of the remaining two excluding the maximum level and the minimum level of the four is there. Like 23, 24 is a brightness information selection circuit that obtains one brightness information from four brightness information, and as a selection method, there is a method of taking the maximum level of four, for example. As described above, the selection circuits 23 and 24 are provided for the purpose of saving the RAM 25 and reducing the load on the CPU 26 by adding the preprocessing. The outputs of the two selection circuits 23 and 24 are sent to the RAM 25 connected to the bus of the CPU 26. In the CPU 26, the height and luminance information read from the RAM 25 is compared with the height information and the luminance information which are obtained from the pre-mounted printed circuit board and are stored in advance, and are mounted for inspection. Determines the quality of the printed circuit board.

As described above, in the present embodiment, the mounted printed circuit board to be inspected is irradiated with a beam spot vertically, and the beam spot is moved together with the photoelectric conversion elements arranged around it so that each point of the mounted printed circuit board Since the changes in height and brightness are measured, each point of the mounted printed circuit board is measured under the same conditions, and good inspection can be expected.

Further, since the reflected light from the mounted printed circuit board is configured to be received by the plurality of photoelectric conversion elements arranged around the beam spot, the reflected light from the mounted printed circuit board has various diffusion characteristics. Even so, it is possible to reduce the fluctuation of the inspection result accompanying it. In the embodiment, both the height and the brightness on the mounted printed circuit board are detected, but when the detection accuracy may be low, only one of them may be inspected. It is a thing.

EFFECTS OF THE INVENTION As described above, according to the present invention, a mounted printed circuit board is irradiated with a beam spot substantially vertically, and a plurality of light receiving optical systems are arranged around the optical axis, and the irradiation and light receiving optical systems are integrated. By measuring and scanning the mounted printed circuit board, it became possible to satisfactorily perform the inspection of the solder surface, which was difficult with the conventional inspection machine.

[Brief description of drawings]

FIG. 1 is a perspective view of a unit of an inspection device in which an optical system for projecting a beam spot and an optical system group for receiving light are integrated in one embodiment of the mounted printed circuit board inspection device of the present invention, and FIG. 2 is the same. FIG. 3 is a perspective view showing a main part of the embodiment, FIG. 3 is a block diagram of an electric circuit of the inspection apparatus, and FIG. 4 is a perspective view of a conventional printed circuit board inspection apparatus. 1 …… Optical system for projecting beam spot, 2,4,6,8 …… Photoelectric conversion element, 3,5,7,9 …… Lens, 10 …… Printed circuit board, 1
1 …… Beam spot, 12 …… Rotating disk, 13,14,15,16…
… Unit inspection device, 19,20,21,22 …… Height and brightness information detection circuit, 23 …… Height information selection circuit, 24 …… Brightness information selection circuit, 25 …… RAM, 26 …… CPU.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-320417 (JP, A) JP-A2-187619 (JP, A) JP-A-2-187615 (JP, A)

Claims (4)

[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. Then, a plurality of beam spots are arranged on the rotating body so that each of the printed board is irradiated with a beam spot in a direction substantially vertical, and the beam spot sequentially scans the printed board as the rotating body rotates. Means and radially arranged around each of the beam spots on the rotating body, receives the reflected light of the beam spot from the printed circuit board, and generates a detection output according to the receiving position of the reflected light. And a plurality of photoelectric conversion means for obtaining the output according to the unevenness on the surface of the printed board as the detection output. . 2. A rotating body that is rotationally driven, a means for moving a printed circuit board to be inspected relative to the rotating body, and a position on substantially the same circumference around the rotation center of the rotating body. Then, a plurality of beam spots are arranged on the rotating body so that each of the printed board is irradiated with a beam spot in a direction substantially vertical, and the beam spot sequentially scans the printed board as the rotating body rotates. Means for radiating the beam spots on the rotator around the respective beam spots, and receives the reflected light of the beam spots from the printed circuit board, and performs a first detection according to the light receiving position of the reflected light. A plurality of photoelectric conversion means for generating an output and a second detection output according to the brightness, and an output according to the unevenness on the printed circuit board is obtained by the first detection output, Second detection output by the inspection apparatus of the populated printed circuit board, characterized in that to obtain an output corresponding to the luminance of each position on the printed circuit board surface. 3. A photoelectric conversion element is arranged within a range of 20 to 30 degrees from the irradiation position of the beam spot on the printed circuit board, and the photoelectric conversion element is arranged in the range of 1 or 2. Inspection device for mounted printed circuit boards. 4. The mounted printed circuit board according to claim 1 or 2, wherein the beam spot is narrowed so as to converge approximately 1 mm above a standard position on the surface of the printed circuit board. Inspection device.