JPS6262253A - Through hole inspector - Google Patents

Abstract

PURPOSE:To enable a high-speed inspection of through-holes moving continuously, by combining a detector for detecting positions of through-holes formed in a light transmitting substrate and an image sensor for picking up images of the through-holes to control the timing of picking up images of through-holes on the basis of information from the detector. CONSTITUTION:A circuit board 11 in which several trains 13a-13c of through holes 13 are formed passes under a detector 14 and then under an image sensor 15. The detector 14 detects the through-holes 13 under it and inputs the resulting information into a control circuit 20. The control circuit 20 calculates the time at which the through-hole 13 arrives under the image sensor 15 from the moving speed or movement of a table 27 moving at a fixed speed and makes the image sensor 15 ready for picking up images at the time. Utilizing light form a light source 16, the element 15 picks up images to check the through-holes 13 for defects.

Description

[Detailed Description of the Invention] [Summary] A defect inspection device for through holes formed in a translucent circuit board is equipped with a detector that detects the position of the through hole and an image sensor that takes an image of the through hole, By controlling the timing of the imaging based on information from the detector, we were able to inspect continuously moving through-holes.

[Industrial application field]

The present invention relates to an improvement in an apparatus for inspecting defects occurring on the inner wall of a through hole formed in a light-transmitting circuit board.

In conductor patterns of double-sided printed wiring boards and multilayer printed wiring boards, and circuit boards with through holes that connect the conductor patterns between the eyebrows, through holes can cause defects such as cuts and pinholes on the plated inner wall. There is.

Since such defects impede the connection and reduce the reliability of the circuit board, it is necessary to inspect them before mounting circuit elements on the circuit board. Various inspection devices have been developed, but these There are difficulties in testing. Therefore, on December 28, 1982, the applicant proposed a device that solved this difficulty by utilizing the translucency of the insulating material used for circuit boards.
The method based on the through-hole inspection method of Japanese Patent Application No. 57-228672, filed on
It has excellent advantages such as making automation possible.

[Conventional technology]

FIG. 6 is a diagram for explaining an embodiment of the through-hole inspection method, in which 1 is a circuit board in which through-holes 4 are formed on a transparent substrate 2, and 3 is a conductor layer adhered to the inner wall of the through-hole 4. , 5 is a mask that covers the illumination side opening of the through hole 4;
7 is a lens constituting the optical system, 8 is a photodetector,
The mask 5 is located on the illumination side of the circuit board 1 and separated from the circuit board 1 by a predetermined distance.

The device configured as above detects the position of the through hole 4 before it is shielded by the mask 5, and then moves the circuit board 1 so that the illumination light 6 illuminates the area including the through hole 4 that is shielded by the mask 5. do. Therefore, if there is a defect 9 in the conductor layer 3, the light that enters the substrate 2 and is dispersed leaks from the defect 9 into the through hole 4, so that the leaked light in the through hole 4 reaches the detection position of the through hole 4. By detecting this with the photodetector 8 through the lens 7, the presence or absence of the defect 9 can be known.

[Problem that the invention seeks to solve]

In the conventional through-hole inspection device, the photodetector 8
The circuit board 1 is configured to move in order to sequentially inspect a plurality of through holes 4 using a one-dimensional sensor such as COD. However, while using a one-dimensional imaging device such as COD allows inspection while continuously moving, it does not have sufficient sensitivity, and if a high-sensitivity TV camera that can take images in low illuminance is used, it is difficult to continuously move the circuit board 1. There is a problem that it cannot be done (image blur occurs), and a countermeasure has been requested.

[Means for solving problems]

FIG. 1 is a diagram showing an outline of a device that is the basic configuration of the present invention.

In FIG. 1, 11 is a circuit board in which a plurality of through holes 13 are formed on a transparent substrate 12, 14 is a detector for detecting the through holes, 15 is an image pickup element for taking images of the through holes 14, and 16 is an image pickup device. a light source 17 facing the element 15;
18 is a projection means for imaging light; 19 is a means for moving the circuit board 11; 20 is a control circuit for the image sensor 15 and the like; and 21 is an imaging inspection circuit.

As shown in FIG.
This is an apparatus for inspecting conductive layer defects on the inner wall of circuit board 11, and includes a light source 16 disposed opposite to one surface of circuit board 11, and a through hole 13 disposed opposite to the other surface of circuit board 11.
a detector 14 for detecting the through hole 13; a means 18 for projecting the imaging light of the through hole 13 onto the image sensor 15 for a short time; a light source 16, the detector 14, and the image sensor 15 or the circuit. Board 1
1 in a direction parallel to the surface of the circuit board 11; and a control circuit 2o that operates the image pickup device 15 and the imaging light projection means 18 based on the detection information of the detector 14. Further, the imaging light projection means 18 is a shutter disposed between the circuit board 11 and the imaging element 15, the imaging light projection means 18 is instantaneous lighting of the light source 16, and the moving means 19 is , image sensor 15 and imaging light projection means 1
The present invention is solved by a through-hole inspection device characterized in that it is configured to be speed-controlled in synchronization with the operation of No. 8.

[Effect]

A plurality of through holes 13 (four in the figure) are arranged in the front-rear direction, and the plurality of through holes 13 (three in the figure) 13a, 13b, 13
The circuit board 11 on which C is formed in the left and right direction is the detector 14
After passing under the image sensor 15, the image pickup device 15 moves to pass under the image sensor 15.

Then, the detector 14 detects, for example, that the through-hole row 13a has passed below it, and the control circuit 20, to which the detection information is input, detects that the through-hole row 13a has passed below the image sensor 15 based on the detection information. When positioned, the imaging device 15 and imaging light projection means 18 are operated.

Then, the through-hole rows 13a that are momentarily irradiated with the illumination light from the light source 17 are imaged by the imaging device 18, and from the image, it is possible to determine whether or not there are defective through-holes 13, that is, through-holes 13 whose interiors are brightly imaged due to defects. The inspection circuit 21 determines the presence or absence.

Therefore, in the present invention, a secondary element such as a TV camera can be used as the image sensor 18, and the image can be taken while the circuit board 11 is moving.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A through-hole inspection apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing an outline of a through-hole inspection device according to a first embodiment of the present invention, FIG. 3 is an example of an image taken by the device, and FIG. 4 is a diagram showing an outline of a through-hole inspection device according to a second embodiment of the present invention. FIG. 5 is a diagram schematically showing a through-hole inspection apparatus according to a third embodiment of the present invention.

In FIG. 2, in which the same reference numerals are used for parts common to those in FIG.
4, a light source facing 4; 23 and 24 a lens system constituting an optical system; 25, a shutter which corresponds to the means 18 in FIG. 1 and is electronically driven using, for example, a liquid crystal panel; 26, a rotary encoder; This is a moving table that is moved by an encoder 26, and the moving table 27 on which the rotary encoder 26 and the circuit board 11 are mounted corresponds to the moving means 19 in FIG.

In the device configured in this way, when the table 27 on which the circuit board 11 is mounted and fixed moves continuously from the left to the right in the figure, the through hole rows 13a, 13b,
13c passes below the detector 14 and then passes below the image sensor 15.

Therefore, the detector 14 detects the through hole 13 passing under it and inputs the information to the control circuit 20. Then! The 1lff1 circuit 20 instantaneously opens and closes the shutter 25 when the through hole 13 that has passed below the detector 14 is located below the image sensor 15 based on the moving speed or amount of movement of the table 27 that moves at a constant speed. ,
The image sensor 15 is brought into an imaging state.

As a result, the image sensor 15 is located below the mask 17.
captures an image of the area including the through hole 13 that covers the illumination side opening using the projection light of the light source 16 that is always on;
If there is a defect in the conductor layer on the inner wall of the through hole 13,
Since the light that enters the substrate 12 and is dispersed leaks from the defect into the through hole 13, the leaked light is detected by the inspection circuit 21 via the lens 24 and the image sensor 15, thereby determining whether or not there is a through hole defect. You can know.

FIG. 3 is an example in which images of four through holes 13 provided in the same row are simultaneously captured by the image sensor 15. In contrast to the defect-free through holes 13, the dark field is inside the circular outline.
The defective through hole 13' becomes visible as a bright circular outline inside.

In FIG. 4, where the same reference numerals are used for parts common to those in FIG. 2, 28 is a strobe device that momentarily lights up the light source 16. This corresponds to the means 18 in Figure 1, and the second
It is operated at the same timing as the shutter 25 shown in the figure is operated.

Therefore, the device of FIG. 4 operates similarly to the device of FIG.
A defect in the through hole 13 can be detected by the inspection circuit 21.

In FIG. 5, in which the same reference numerals are used for parts common to those in FIG.

Therefore, the image sensor 15 and the shutter 25 are configured to operate after a certain period of time has elapsed after the detector 14 detects the through hole 13, and the encoder 26 operates when the through hole 13 is detected. The rotation speed is controlled by the control circuit 20 so that the image sensor 15 is positioned at an imaging position facing the image sensor 15.

Therefore, the apparatus shown in FIG. 5 is capable of rapid forwarding during inspection, and is effective, for example, for inspecting circuit boards with widely spaced through-hole rows.

〔Effect of the invention〕

As explained above, according to the present invention, a two-dimensional sensor with higher sensitivity than a -dimensional sensor is used as an image sensor, and it becomes possible to inspect the inner wall conductor layer of a through-hole in a continuously moving translucent circuit board. , the effect of speeding up the inspection is remarkable.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an outline of a device which is the basic configuration of the present invention, Fig. 2 is a diagram showing an outline of a through-hole inspection device which is a first embodiment of the invention, and Fig. 3 is a diagram showing an outline of a through-hole inspection device which is a first embodiment of the invention. 4 shows an overview of a through-hole inspection device according to a second embodiment of the present invention, and FIG. 5 shows an overview of a through-hole inspection device according to a third embodiment of the present invention. FIG. 6 is a diagram for explaining a conventional through-hole inspection method. In the figure, 11 is a translucent circuit board, 13 is a through hole, 14 is a detector, 15 is an image sensor, 16 is a light source, 1 is a means for projecting imaging light for a short time, and 19 is a circuit board 11 etc. A moving means, 20 a control circuit, 25 a shutter, and 28 a strobe device are shown. 2θ A certain diagram of the basic configuration of the present invention

Claims (4)

[Claims] (1) A device for inspecting defects in the conductive layer on the inner wall of a through hole (13) formed in a light-transmitting circuit board (11), which is disposed opposite to one surface of the circuit board (11). light source(
16), a detector (14) arranged to face the other surface of the circuit board (11) to detect the through hole (13), and an image sensor (15) to image the through hole (13); means (18) for projecting the imaging light of the through hole (13) onto the imaging device (15) for a short time; the light source (16), the detector (14), and the imaging device (15);
) or one of the circuit boards (11).
); and means (19) for moving the image sensor (15) in a direction parallel to the plane of the image sensor (15) based on the detection information of the detector (14).
and a control circuit (20) for operating the imaging light projection means (18). (2) The imaging light projection means (18) may be arranged so that the circuit board (
11) and the image pickup element (15). (3) The imaging light projection means (18) may include the light source (16).
2. The through-hole inspection device according to claim 1, wherein the through-hole inspection device is characterized by instantaneous lighting. (4) The moving means (19) includes the image sensor (15)
The through-hole inspection apparatus according to claim 1, characterized in that the through-hole inspection apparatus is configured to be speed-controlled in synchronization with the operation of the imaging light projection means (18).