JPH0332731B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the through-hole light shielding method, the present invention aims to eliminate the need for pre-treatment for through-hole light shielding of a printed board, and a printed board is provided on one side of the printed board. A light provided on the other side of the printed board in a predetermined positional relationship with the inspection light source is used to detect that the diffused light that diffuses inside the light-transmissive insulating substrate leaks into the through hole when illuminated by the inspection light source. In a through-hole inspection device that detects defects in through-holes by sensing them with a detector, a surface of a rotating body is pressed against one side of the printed board, and there is a gap between the printed board and the printed board. A rotating body mechanism is provided that causes the rotating body surface to move with relative movement, and the rotating body surface is tightly fitted into the through hole to shield the through hole from light.

[Industrial application field]

The present invention relates to a through-hole inspection device for printed circuit boards, and more particularly to an improvement in a light shielding method for through-holes.

Through-hole plating is widely used to connect front and back conductors of double-sided printed boards or to connect interlayer conductors of multilayer printed boards. In this through-hole plating method, holes are pre-drilled in an insulating substrate on which conductors are laminated, and a plating layer is chemically or electrically formed on the inner wall of the through-hole to electrically connect the conductors. However, since the plating layer has a thickness on the order of microns, the inner wall surface of the through hole is extremely uneven, and the diameter is small, defects such as pinholes and cuts often occur in the plating layer forming the through hole. If the defects in the plating layer are large, this leads to poor electrical continuity between the conductors, which poses a major problem in terms of the reliability of the printed board. Therefore, it is desired that defects in such through holes can be easily and reliably inspected.

[Conventional technology]

Conventionally, through-hole defect inspection involves attaching a mask that shields the through-hole from light to one side of the printed circuit board, which allows the light from the inspection light source that is directed toward the surface of the printed board that is in contact with the mask to enter the through-hole. I was trying to prevent it from entering.

[Problem to be solved by the invention]

However, such a through-hole light shielding method requires alignment of the mask with respect to the printed board, and therefore has the disadvantage that preparations for through-hole inspection are complicated and affect the efficiency of inspection work.

The present invention solves the above-mentioned conventional drawbacks, and eliminates the need for prior preparation for through-hole light shielding as in the prior art, and improves inspection speed and work efficiency. It is an object of the present invention to provide a through-hole inspection device for a printed board that can be used regardless of the circumstances.

[Means to solve the problem]

The present invention provides a method for detecting that when a printed board is illuminated by an inspection light source provided on one side of the printed board, diffused light diffused within a light-transmissive insulating substrate leaks into a through hole on the other side of the printed board. A rotating body mechanism is provided on one side of the printed board of the through-hole inspection device that detects defects in the through-hole by sensing with a photodetector provided in a predetermined positional relationship with the inspection light source, and detects defects on the rotating body surface. The through-hole is configured to be tightly fitted into the through-hole to shield the through-hole from light. The rotating body mechanism has a rotating body surface pressed against one side of the printed board, and is configured to cause relative movement between the rotating body surface and the printed board and movement of the rotating body surface.

[Effect]

When the rotating body surface of the rotating body mechanism is pressed against the surface of the printed board other than the through hole due to relative movement between the printed board and the rotating body mechanism, the light from the inspection light source that has passed through the through hole to be inspected is By detecting with a photodetector, the through-hole position detection signal can be obtained.

After that, when the relative movement progresses and the surface of the rotating body closely fits into the through hole to be inspected and blocks light, it is determined whether or not there is light from the inspection light source leaking into the through hole. Detected by the photodetector. At this time, the photodetector outputs a signal indicating its presence or absence.

Based on the signal representing the presence or absence of the through hole and the through hole position detection signal, a signal indicating whether or not there is a defect in the through hole to be inspected is output.

The present invention does not require the conventional pretreatment for through-hole light shielding in such through-hole defect inspection.

〔Example〕

1 and 2 show an embodiment of the through-hole inspection device according to the present invention, 1 is a printed board to be inspected, and the substrate material 2 constituting this printed board 1 is made of glass fiber, for example. The substrate material 2 is made of a light-transmitting material impregnated with epoxy resin, and a plating layer 3 is formed on the inner wall of the through hole 2a drilled in the substrate material 2, thereby forming a through hole 4 for electrically connecting the front and back conductors. It is set up.

One side of the printer board 1 is irradiated with light 5 from a defect inspection light source (not shown), and the illumination side of the printed board 1 is provided with a rotating through-hole in the form of a roll for light shielding. The rotary body 6 has a length that simultaneously shields a plurality of through holes 4 from light as shown in FIG. 2, and both ends of its support shaft 7 are rotatably attached to a fixed part. The rotating body 6 is supported by an attached arm 8, and a tension spring 9 is stretched between the arm 8 and the fixed part, so that the rotary body 6 can be brought into pressure contact with the light-irradiated surface of the printed board 1. The printed board 1 is set on an X-Y stage (not shown), and when the X-Y stage is moved in the direction of arrow A, the printed board 1 is rotated so that it is tightly fitted into the through hole 4 of the printed board 1. The body 6 shields the through hole 4 from light so that the illumination light 5 does not enter the through hole 4.

Reference numeral 10 denotes a photodetector disposed on the other side of the printed board 1 facing the rotating body 6, and this photodetector 10 includes a CCD (Charge Coupled Device),
It is composed of a line sensor, etc., and is designed to simultaneously sense through holes 4 corresponding to the number of light shielded by the rotating body 6. Further, the photodetector 10
A lens 11 is disposed between the printed board 1 and the opposite printed board 1 for condensing transmitted light leaking into the through hole 4 onto a photodetector 10.

In this embodiment with the above configuration, X-
When the printed board 1 is moved one pitch in the direction of arrow A by the indexing operation of the Y stage, the printed board 1
The rotating body 6, which is pressed against the light irradiation surface of the rotor 6, is fitted into the through hole 4, thereby sealing the opening of the through hole 4 on the illumination light 5 side, and the illumination light 5 enters the through hole 4. to prevent

On the other hand, the light 5 that has entered the substrate material 2 of the printed board 1 from around the rotating body 6 is diffused inside the substrate material 2. At this time, if there is a defect 3a such as a pinhole in the through hole 4, the diffused light leaks into the through hole 4 through the defect 3a, causing the inside of the through hole to shine, and at the same time, the light is transmitted to the photodetector 10 by the lens 11. The light is focused, and the photodetector 10 detects the light, thereby determining that the through hole 4 is defective.

Furthermore, if there is no defect in the through-hole 4, the light diffused within the substrate material 2 will not leak into the through-hole 4, so the photodetector 10 will not operate.

In this embodiment as described above, the through hole 4 is shielded from light by the rotating body 6 which is pressed against the light irradiation surface of the printed board 1 and rotated as the printed board 1 is moved. This eliminates the need for alignment work between the mask and through-holes, which is required in the conventional method using a mask pattern, and accordingly, preparatory work for inspection is simplified, and inspection work efficiency can be improved. In addition, since the light shielding of the through hole 4 is a roll-shaped rotating body, the through hole 4 formed on the printed board
Even if the pitch and size of the image are changed, the required light shielding can be ensured, making it versatile, and also speeding up the inspection.

In the above embodiment, the rotating body 6 is shaped like a roll, but it may also be shaped like a ball.
The rotating body 6 may be moved instead of moving the printed board. In this case, the illumination light source and photodetector must be moved together with the rotating body.

〔Effect of the invention〕

As described above in detail, according to the present invention,
When the through-hole is pressed against the light-irradiated surface of the printed board and is moved and tightly fitted into the through-hole, the through-hole is shielded from light by the surface of the rotating body. Preparation for inspection is no longer required, which improves inspection work efficiency and speeds up inspection, as well as allowing the same rotating body to be used for printed boards with different through-hole pitches and diameters. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a perspective view showing an example of a rotating body used in the present invention. In Figures 1 and 2, 1 is a printed board;
2 is a substrate material, 4 is a through hole, 5 is an illumination light, 6
10 is a rotating body, 10 is a photodetector, and 11 is a lens.

Claims (1)

[Scope of Claims] 1. When a printed board is illuminated by an inspection light source provided on one side of the printed board, it is possible to detect that diffused light diffused within a light-transmissive insulating substrate leaks into a through hole of the printed board. In a through-hole inspection device that detects defects in through-holes by detecting them with a photodetector provided on the other side in a predetermined positional relationship with the inspection light source, the rotating body surface is printed on one side of the printed board. A rotating body mechanism is provided that is pressed against one side of the board and can cause the rotating body surface to move as well as relative movement with the printed board, and the rotating body surface is tightly fitted into the through hole. A through-hole inspection device for a printed circuit board, characterized in that the through-hole is shielded from light.