JPH0332732B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a through-hole detection device for inspecting voids or defects in through-holes formed on a printed circuit board.

(b) Background of the technology In order to electrically connect the conductive parts on the front and back sides of a printed board, a through hole is provided in the printed board and the inner surface of the through hole is covered with a conductive layer such as copper. Then, through-hole processing is performed. From the viewpoint of reliability, voids or defects must be absolutely avoided in the through-holes processed in this manner.

(c) Prior Art and Problems Conventionally, a through hole has a width or diameter of about 1 mm and a thickness of about 1 mm, so a visual inspection was performed to inspect the inner wall of the through hole for voids, etc. However, as technology improves the degree of integration of semiconductor devices, the width or diameter of the through hole has been gradually reduced to about 0.2 mm. On the other hand, the thickness of the through hole was increased to about 3 mm, and the shape of the through hole became elongated, making visual inspection virtually impossible. Therefore, a method of optically detecting light leakage using a device as shown in FIG. 1 has come into use. As shown in FIG. 1, a printed circuit board 1 is provided with a through hole 2, and the inner wall of the through hole 2 is coated with a conductive layer 3. Through-hole voids or defects 4 are formed in the conductive layer 3 . Light 5 emitted from a light source (not shown) passes through a portion other than the light-shielding mask 6 provided at the through-hole opening and enters the printed board. At this time, a part of the light 7 leaks through the through hole void or defect 4 into the through hole and passes through the lens 8 to the CCD.
It is detected by a detector 9 such as. Photodetector 9
What is detected by this is circular light 7a (light leakage) within the conductive layer 3, as shown in FIG. Since the through-hole void inspection apparatus shown in FIG. 1 has a light source and a light-shielding mask separated, a holder is required for each of the light source and the mask, and it is also necessary to adjust their positions. Furthermore, the conventional device required optical systems on both sides of the printed board, which was inconvenient in terms of space.

(d) Object of the Invention In view of the above drawbacks, an object of the present invention is to provide a through-hole detection device whose optical system can be easily adjusted.

Another object of the present invention is to provide a through-hole detection device in which the space occupied by the entire device is reduced.

(E) Structure of the Invention An object of the present invention is to provide a three-hole inspection device for inspecting voids or defects in through-holes formed in a printed board; The illumination means and the light shielding means are provided with a light shielding means for shielding light from entering the opening of the hole, and a light detection device for detecting light emitted from the illumination means and light leaking from the void or defect. and a light detection device are disposed on the same side with respect to the printed board, and the light shielding means has a cylindrical rotating body that rotates on the surface of the printed board, so that the printed board is continuously This is achieved by a through-hole detection device characterized by being horizontally movable.

(F) Embodiments of the invention Examples of the invention will be described below based on the drawings. FIG. 3 is a schematic sectional view for explaining an embodiment according to the present invention.

In FIG. 3, two illumination lights 15 are arranged to illuminate the sides of a through hole 12 formed in a printed board 11, and two illumination lights 15 are arranged to illuminate the side surfaces of a through hole 12 formed in a printed board 11.
Near the two openings, two sets of light shielding plates 16a and light shielding rolls 16b are arranged so as to be connected and face each other. The light-shielding plate 16a and the light-shielding roll 16b are provided near the through-hole opening, and the roll 16b moves on the printed board, so that the light from the illumination lamp 15 does not enter the opening. Also, for example, a television camera detects light leaking into the through hole from voids or defects 14 in the conductive layer constituting the through hole 12.
A light detection device 19 such as a CCD is provided at the upper center of the roll 16b.

A method for inspecting through holes using the above-mentioned through hole inspection apparatus of the present invention will be described below.

A printed circuit board 11 having a through hole 12 is placed on a moving stage 10, and the apparatus is moved near the opening of the through hole. A through hole 12 in which a lighting lamp 15 is attached is illuminated from the side. If there is a defect 14 in the conductive layer constituting the through hole, the light emitted from the illumination lamp 15 leaks from the defect 14 into the through hole 12, and is detected by an optical inspection device installed to optically detect the leakage of light. It is then detected. The light shielding device is a device that blocks the light emitted from the illumination lamp 15 from entering through the opening of the through hole, and the light shielding means used in the part that comes into contact with the printed board is designed so that it is easy to move on the printed board and does not damage the printed board. The roll is preferably made of rubber,
etc. are preferred. Further, it is preferable that the gap between the rolls placed opposite to each other across the through hole 12 is set appropriately in advance according to the inner diameter of the through hole.

(G) Effects of the Invention As explained above, since the device according to the present invention is arranged on the same side of the printed board, the usable space is smaller compared to the conventional device which requires installation on both sides. It also becomes possible to easily adjust the device.

[Brief explanation of the drawing]

1 and 2 are a schematic sectional view and a plan view for explaining the prior art, and FIG. 3 is a schematic sectional view for explaining one embodiment of the present invention. 1, 11... Printed board, 2, 12... Through hole, 3, 13... Conductive layer, 4, 14... Void or defect, 5... Light, 6... Light shielding mask for shielding through hole, 7, 7a...Light leakage, 8,18...
Lens, 9...Photodetector, 10...Movement stage, 15...Illumination lamp for void or defect detection, 16
a... Light shielding plate, 16b... Light shielding roll, 19...
Light detection device.

Claims (1)

[Claims] 1. A through-hole inspection device for inspecting voids or defects in through-holes formed on a printed circuit board, including at least two illumination means and a light shielding device to prevent light emitted from the illumination means from entering the opening of the through-hole. and a light detection device that detects light emitted from the illumination means leaking from the void or defect, and the illumination means, the light shielding means, and the light detection device are configured to The light shielding means includes a cylindrical rotating body that rotates on the surface of the printed board, so that the printed board can be continuously moved horizontally. Through-hole detection device.