JPH01320416A - Inspection instrument for packaged printed wiring board - Google Patents

Abstract

PURPOSE:To perform data fetching inspection at once on a packaged printed wiring board by storing the height information of each point obtained by scanning the surface of the circuit board circular-arcuately in a RAM after transforming the information into an orthogonal coordinate system. CONSTITUTION:An encoder 36 is provided to a rotary disk 12 and the rotational angle information of the disk 12 is obtained by means of a counter 37. When a mounted printed wiring board 10 comes to a specific position, a counter 35 for counting drive pulses impressed upon a pulse motor 31 is reset by a sensor 33 and the moving distance information of the substrate 10 is obtained. Each information of the height and luminance of an inspecting point on the substrate 10 in polar coordinates are obtained from the rotational angle information and moving distance information. The address of an orthogonal coordinate system corresponding to the polar coordinates is stored in a ROM 38 and the output of the ROM 38 is made to correspond to the address of a RAM 25 for storing height and luminance information and detecting information corresponding to the address of the RAM 25 is successively stored in the RAM 2. Therefore, when a CPU 26 performs comparing processing on the detecting information of the RAM 25 and teaching data stored in a RAM 39, inspection of the substrate 10 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an inspection device for mounted printed circuit boards, and in particular uses a focused beam spot to detect misalignment of mounted components, solder defects, and solder bridges. The purpose of this test is to examine the following:

Conventional technology Conventionally, misalignment of components on a mounted printed circuit board.

There is a method using a multi-slit light and a camera as a device to automatically inspect for missing parts, solder defects, solder bridges, etc.

This will be explained below with reference to the drawings. In Figure 6,
65 and 56 are irradiation devices that irradiate slit light, 64 is a camera, and 57 is a mounted printed circuit board. By irradiating two slit lights onto the mounted printed circuit board 67 obliquely from above so that their optical axes are perpendicular to each other and observing it with the camera 64 from above, the height of the mounted component can be measured based on the principle of the triangular If4IJ amount. Furthermore, by alternately irradiating the parts with the multi-slit irradiation devices 55 and 56 at this time, the component position in the +7 direction (see FIG. 6) can be determined.

Problems to be Solved by the Invention However, as mentioned above, the inspection device using a camera has the following problems:
Inevitably, there is a limit to the observation field of view of a camera, and it is necessary to inspect one printed circuit board by dividing it into a plurality of observation fields. For this reason, in the case of a large printed circuit board, the number of divisions increases, and due to the arrangement of components, it takes time to consider a division method for efficient inspection. Additionally, large parts cannot be seen in the camera's field of view, making it necessary to separate the parts themselves. Therefore, the inspection accuracy decreases due to division and the inspection means becomes complicated.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an apparatus that takes in inspection data of a mounted printed circuit board every time and performs an inspection satisfactorily.

Means for Solving the Problems The inspection apparatus for a mounted printed circuit board of the present invention includes a feeding means for driving a printed circuit board to be inspected by a predetermined distance in response to the application of a drive on/off signal, and a rotationally driven an inspection means disposed on a rotating body, scanning the printed circuit board in an arc shape with a beam spot as the rotating body rotates, and obtaining detection information according to the height of the printed circuit board surface using the reflected light; a counter for counting driving pulses applied to the feeding means; a means for detecting that the printed circuit board has been fed to a predetermined position and resetting the counter; and a counter for counting the driving pulses applied to the feeding means; rotation angle detection means for outputting a numerical value; means for outputting a predetermined address determined by the count value of the counter and the value of the angle detection means; and means for outputting the detected information sequentially according to the address. The present invention is characterized by comprising a storage means for storing the information, and a comparison means for comparing the detected information read out from the storage means with reference information stored in advance.

Operation According to the above configuration, the inspection means for detecting the height of the printed circuit board surface is configured to scan the printed circuit board surface as the rotating body rotates, so even relatively large printed circuit boards can be continuously scanned. Sequential inspection is possible, and the height information of each point obtained by scanning the printed circuit board surface in an arc shape is converted to an orthogonal coordinate system and then stored in the RAM. Since the observation data is placed in the same coordinate system that humans observe, it is more convenient for subsequent data processing than when the data is placed in the polar coordinate system.

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. 2 is a perspective view of a unit inspection device in which a beam spot projecting optical system and a light receiving optical system group are integrated.

1 is an optical system for projecting a beam spot using, for example, a laser; 2, 4, and 6.8 are systems for receiving reflected light from a reflecting surface of the beam spot and obtaining information on the height and brightness of the reflecting surface; This is a photoelectric conversion element such as a semiconductor device detection element (hereinafter referred to as PSD). This PSD has a certain predetermined length, and the output of a plurality of output terminals changes relatively depending on the irradiation position of the beam spot.
It is also possible to use an OD line sensor or the like. 3,
5, 7.9, in order to perform triangulation, the reflected beam spot from the mounted printed circuit board is connected to the photoelectric conversion elements 2, 4.
, 6.8, respectively. These photoelectric conversion elements and lenses are
They are arranged around the optical axis of the beam spot, and in this example, 4
The sets are arranged at equal intervals on the same circumference centered on the beam spot. 10 is a mounted printed circuit board, and 11 is a beam spot, which is irradiated almost perpendicularly to 1° of the mounted printed circuit board.

FIG. 3 is a perspective view of the entire inspection device. 13°14.
Reference numerals 15 and 16 are one unit inspection device in which the optical system group shown in FIG. 2 is integrated. 12 is a drive source such as a motor (
This is a rotating disk that is rotated at a substantially constant speed by a motor (not shown). The unit inspection devices 13, 14, 15, and 16 sequentially scan the experimental method printed circuit board 10 with 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. It is arranged like this.

Therefore, the experimental printed circuit board 10 is shown in FIG.
7 + "By sequentially moving in the y direction of the coordinate system, it becomes possible to scan the entire experimental printed circuit board 1o with the beam spot. 17 is currently the unit inspection device 1.
4 indicates the trajectory being scanned, and 18 indicates the trajectory scanned by the unit inspection device 15 immediately before. In FIG. 3, when the unit inspection device 14 completes scanning, the experimental printed circuit board 10 moves in the y-axis direction, and the movement ends before the next unit inspection device 13 starts scanning.
There is no wasted time and the inspection can be completed in the minimum amount of time.

FIG. 4 shows an electric circuit of the present device for obtaining height information and brightness information by calculating two current outputs whose values change relatively depending on the irradiation position from the photoelectric conversion element. 1
9 is a height and brightness information detection circuit that obtains height information from the two current outputs of the photoelectric conversion element 2 through a divider 62, and also obtains brightness information from the sum of the two current outputs through an operational amplifier 53. It is. 20, 21.22 are also similar to the height and brightness information detection circuit 19, and are connected to the photoelectric conversion elements 4, 6.8. In this case, since four photoelectric conversion elements are used, four pieces of height and brightness information are output for one light spot. 23 is a height information selection circuit that obtains one piece of height information from four pieces of height information, and the selection method is, for example, a method of removing the maximum level and minimum V-pel among the four pieces of information and taking the average of the remaining two pieces. There is. Similarly to 23, 24 is a brightness information selection circuit which obtains one brightness information from four pieces of brightness information, and the selection method includes, for example, a method of selecting the maximum level among the four pieces of brightness information. In this way, the two height and brightness information selection circuits 23 and 24 are provided for the purpose of saving the RAM 25 and reducing the load on the CPU 26 by performing preprocessing.

The outputs of the two height and brightness information selection circuits 23 and 24 are sent to the RAM 2B connected to the bus of the CPU 26. The CPU 26 compares the height and brightness information read out from the RAM 26 with the height information and brightness information stored in advance and obtained from the reference experimental printed circuit board, and compares the height and brightness information read from the RAM 26 with the height information and brightness information stored in advance from the experimental printed circuit board to be inspected. Determine the quality of the board.

FIG. 1 is a configuration diagram of an experimental printed circuit board feeding device and a sensor rotating section. The unit inspection device 15 is a rotating disk 1
2, and scans in an arc. The rotary disk 12 is provided with an encoder 36 for obtaining rotation angle information, and a counter 37 that measures output pulses from the encoder 36 obtains the rotation angle information. 31 is a pulse motor for feeding printed circuit boards;
In synchronization with the rotation of the rotating disk 12, the experimental printed circuit board 10 is sent in the direction indicated by the arrow. A pulse counting counter 36 (driving that counts the driving pulses applied to the I-less motor 31) is provided, and when the experimental printed circuit board 1o moves to a predetermined position, the sensor 33 activates the driving pulse. The L/S counting counter 36 is reset. Information on the moving distance of the experimental printed circuit board can be obtained from the count value of the drive pulse counting counter 35. Based on the rotation angle information and the movement distance information, height information and brightness information of the inspection point on the experimental printed circuit board 1o in the polar coordinate system are obtained. Here, when storing the height and brightness information in the polar coordinate system directly on the iRAM, unlike the world normally observed by humans, the information is stored according to the position on the printed circuit board where the component is mounted. Since the shape of the same part changes, a problem arises in that the same inspection algorithm cannot be used to inspect the same part, resulting in a significant drop in data processing efficiency. Therefore, it is more efficient to perform information processing by converting from a polar coordinate system to a rectangular coordinate system.

In this embodiment, a ROM 38 is used as the converting section, in which addresses of orthogonal coordinate systems corresponding to the respective polar coordinate systems are stored in advance. The ROM converted to a Cartesian coordinate system
The output of 38 is made to correspond to the address of the RAM 25 for storing the height and brightness information, and the detection information corresponding to the address is sequentially stored. The CPU 26 compares the detected information stored in the RAM 25 with teaching data stored in the RAM 39 in advance, and the printed circuit board 1o is inspected.

Two sets of RAMs 25 for storing the detection information are provided, one RAM stores the detection information of the mounting method printed circuit board currently being inspected, and the other RAM stores the detection information of the mounting method printed circuit board currently being inspected. The detection information stored in the printed circuit board is read out, compared with the teaching data, and processed. Each time the printed circuit board is replaced, 2
The functions of the memory RAMs in each set are switched to alternately perform the above processing, thereby achieving high efficiency through parallel processing.

In addition, in this embodiment, in order to inspect the printed circuit board with high precision, the output of the encoder 36 is used to move the printed circuit board by a predetermined distance with respect to 1/4 rotation of the rotating disk 12. The drive pulse generator 34 is controlled to synchronize the rotation of the pulse motor 31 with the movement of the printed circuit board. However, if the inspection accuracy of the printed circuit board to be inspected is not required, the pulse motor 3
1 and the rotation of the rotating disk 12 do not need to be precisely synchronized.

As described above, in this embodiment, a beam spot is irradiated perpendicularly to the mounted printed circuit board to be inspected, and each point on the mounted printed circuit board is Since this method measures changes in the height and brightness of the printed circuit board, each point on the printed circuit board is measured under the same conditions, and good inspection can be expected.

In addition, since the configuration is such that the reflected light from the mounted printed circuit board is received by multiple photoelectric conversion elements arranged around the beam spot, the reflected light from the mounted printed circuit board has various diffusion characteristics. Even if this happens, the fluctuations in test results caused by this can be reduced. In the embodiment, the mounting method is configured to detect both the height and the brightness on the printed circuit board, but if it is acceptable even if the inspection accuracy is low, the configuration may be configured to inspect only one of them. It is something.

Effects of the Invention As described above, according to the present invention, the height and height of the mounting printed circuit board that is sequentially scanned in an arc shape by the rotary body in which the beam spot projection/reception optical system is arranged and the inspected printed circuit board feeding means is After converting the luminance data to Cartesian coordinates, RA
Since the configuration is such that the data is stored in M, it is more convenient for subsequent data processing than when the data is arranged in the polar coordinate system.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a printed circuit board feeding device and a sensor rotating section in an embodiment of the mounting method printed circuit board inspection device of the present invention, and Fig. 2 shows a beam spot projecting optical system and a light receiving optical system group integrated. A perspective view of one unit of inspection equipment,
FIG. 3 is a perspective view showing the main parts of the same embodiment, FIG. 4 is a block diagram of an electric circuit of the same inspection device, and FIG. 5 is a perspective view of a conventional printed circuit board inspection device. 1... Optical system for beam spot projection, -2, 4
. 6.8...Photoelectric conversion element, 3,5,7.9...
... Lens, 1o ... Printed circuit board, 11
...Beam spot, 12...Rotating disk, 13. j4, 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...RA
M, 26... CPU, 31... Printed circuit board drive pulse motor, 33... Counter reset sensor, 34... Drive pulse generator, 35... ... Drive pulse counting counter, 3
6... Own encoder, 37... Counter, 38... ROM for coordinate conversion, 39...
...RAM for storing teaching data. Name of agent: Patent attorney Toshio Nakao and one other person
RAM 26-CP (J 3/--Buson yxu, U-motion pulse motor-33-11 counter t=ytosenzu 3z--Enboo goo 39'--Teaching data) f4RAM collection Figure 2 ＼ Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A feeding means for driving a printed circuit board to be inspected by a predetermined distance in response to the application of a driving pulse; and a feeding means arranged on a rotating body that is driven to rotate, and moving the printed circuit board to a beam spot as the rotating body rotates. an inspection means that scans in an arc shape with the printed circuit board and uses the reflected light to obtain detection information according to the height of the printed circuit board surface; a counter that counts driving pulses applied to the feeding means; means for detecting that the inspection means has been sent to the specified position and resetting the counter; rotation angle detection means for outputting a counted value according to the rotational angle of the inspection means; means for outputting a predetermined address determined by a value; a storage means for sequentially storing the detection information according to the address; An inspection device for a mounted printed circuit board, comprising comparison means for comparing the information with reference information.