JPS62162981A - Through-hole inspecting method for multi-layered printed board - Google Patents

Abstract

PURPOSE:To photodetect ultraviolet rays by a photodetection sensor above a through-hole and to detect the defective part of the through-hole of a multi- layered laminated plate by simple constitution and with high accuracy by providing a mercury vapor lamp which emits ultraviolet rays from the outside of a lid provided at one end of the through-hole coated with a fluorescent agent. CONSTITUTION:The defective part 4 of the through-hole 1 of the laminate plate 6 of a multi-layered printed board is coated with the fluorescent agent 7 and one end of the through-hole 1 is shielded by the lid 2. The mercury vapor lamp 8 which emits ultraviolet rays is arranged outside the lid 2 and the fluorescent agent 7 applied to the defective part 4 is excited with the ultraviolet rays to illuminate. This excited ultraviolet rays are photodetected by a photodetection sensor 5 arranged at the other end part of the through-hole 1 to detect the defective part 4 of the through-hole 1. Then, the defective part 4 of the through- hole of the laminate plate 6 is detected by the simple constitution and with high accuracy to enable fine defects to be detected.

Description

[Detailed Description of the Invention] [Summary] A through-hole inspection method for a multilayer printed board, in which a fluorescent material is applied to the defective part of the through-hole, and ultraviolet light irradiated from a mercury lamp hits the fluorescent material in the defective part and generates excitation. It is configured to detect defective parts by receiving fluorescent light with a light-receiving sensor, and by utilizing the fact that a considerable amount of excited fluorescent light can be obtained with weak ultraviolet light, it is possible to detect minute defective parts of through-holes. .

[Industrial application field]

The present invention relates to a through-hole inspection method for multilayer printed boards,
In particular, the present invention relates to a through-hole inspection method for a multilayer printed board that has a simple configuration and is improved so that minute defects in through-holes can be detected.

In recent years, printed wiring boards have become increasingly multi-layered, and there is a demand for an inspection method that can detect minute defects such as hole holes in thick laminates with a simple configuration.

[Conventional technology]

FIG. 3 shows a schematic diagram of the "through-hole light leakage method" which has been commonly used in the past.

In Fig. 3, the through hole 1 has a cylindrical shape plated with gold paint, and an M2 is provided at one end of the through hole 1 to prevent light from a halogen lamp 3 installed below the lid 2 from directly entering the hole. When light is irradiated onto one surface of the multilayer printed board (hereinafter referred to as laminate board) 6, if there are no defects in the through holes, no light will leak; if there are holes or cuts in the plating, in other words, if there are defects If so, light leaks into the through hole, passes through the through hole, and is received by the light receiving sensor 5 provided above the through hole.

In this way, a defective portion of the through hole is detected by detecting leaked light passing through the through hole with the light receiving sensor 5.

[Problem that the invention seeks to solve]

In the above conventional through-hole inspection method, the laminate 6
As the laminate becomes multi-layered, its thickness increases, and as a result, the light from the halogen lamp 3 is attenuated in proportion to the thickness, causing through-hole defects and minute defects in the upper laminate 6. There is a problem in that the leakage light passing through becomes weaker, and the light receiving sensitivity of the light receiving sensor 5 decreases, making it impossible to detect the defective part.

On the other hand, in order to increase the amount of light leakage from defective parts, there is a method to increase the amount of irradiation light by increasing the capacity of the halogen lamp. Other problems may occur.

The present invention was created in view of these points, and an object of the present invention is to provide a through-hole inspection method for a multilayer printed board, which has a simple configuration and is capable of detecting minute defects in through-holes.

[Means for solving problems]

FIG. 1 is a schematic diagram of the through-hole inspection method of the present invention, and FIG. 2 is an enlarged view of a through-hole defective portion of the present invention. In FIG. 2, a fluorescent agent 7 is applied to the defective portion 4 of the through-hole 1.

Next, as shown in FIG. 1, one end of the through hole 1 is
A mercury lamp 8 is provided which emits ultraviolet light from below the lid 2, and a light receiving sensor 5 is provided above the through hole l.

[Effect]

Ultraviolet light irradiated onto the surface of the laminated plate 6 from the mercury lamp 8 passes through the laminated plate 6 and is incident on the fluorescent agent 7 applied to the defective portion 4 of the through hole I.

When this incident ultraviolet light hits the fluorescent agent 7, an amount of fluorescent light corresponding to the amount of ultraviolet light is generated. The generated fluorescent light passes through the through hole 1 and is received by the light receiving sensor 5, and the defective portion 4 of the through hole 1 is detected.

In the present invention, the ultraviolet light irradiated from the mercury lamp 8 is applied to the defective portion 4.
It uses excited fluorescent light that generates a considerable amount of fluorescent light when it hits the fluorescent agent 7 applied to the laminate plate, and even a weak irradiation light that passes through the laminate plate 6 can generate a considerable amount of fluorescent light. It becomes possible to detect upper defects and minute defects.

〔Example〕

FIG. 1 is a schematic diagram of the through-hole inspection method of the present invention, and FIG. 2 is an enlarged view of a through-hole defective portion of the present invention.

The through-hole inspection method of the present invention is as shown in FIG.
A fluorescent agent 7 is applied to the defective part 4 of the through hole 1, and one end of the through hole 1 is covered with M2 as shown in FIG. , a light receiving sensor 5 is provided above the through hole 1.

To apply the fluorescent agent 7 to the defective part 4, for example, a syringe or the like is used to inject the fluorescent solution into the through-hole hole, and by leaving it for a certain period of time, a fluorescent coating is created on the inner wall of the through-hole and the defective part 4. Of course, a method of immersion in a fluorescent solution may also be used.

Ultraviolet light is irradiated from a mercury lamp 8 onto the surface of the laminated plate 6 where one end of the through hole 1 is shielded by the lid 2.

If there is no defect 4 in the through-hole 1, the irradiated ultraviolet light is blocked by the through-hole plating and does not enter the through-hole (it passes through the laminated plate 6 and is emitted upward).

Now, if there is a defective part 4 in the through hole 1, the irradiated ultraviolet light enters the defective part 4 of the through hole, hits the fluorescent agent 7 applied to the defective part 4, and generates a considerable amount of fluorescent light in the fluorescent material 7. do.

Fluorescent light generated by the fluorescent material 7 passes through the through hole 1 and is received by the light receiving sensor 5, and the defective portion 4 of the through hole 1 is detected.

That is, the through-hole inspection of the present invention utilizes excited fluorescence in which ultraviolet light irradiated from the mercury lamp 8 hits the fluorescent agent 7 applied to the defective part 4 and generates a considerable amount of fluorescence.
Since a considerable amount of fluorescent light can be obtained even with weak irradiation light passing through the laminated plate 6, it is possible to detect defects and minute defects above the laminated plate.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to detect through-hole defects and minute defects in a thick multi-layered laminate with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a through-hole inspection method of the present invention, FIG. 2 is a schematic diagram of a through-hole defective portion of the present invention, and FIG. 3 is a schematic diagram of a conventional through-hole inspection method. In the figure, ■ is a through hole, 2 is a lid, 3 is a halogen lamp, 4 is a defective part, 5 is a light receiving sensor, 6 is a laminate, 7 is a fluorescent agent, and 8 is a mercury lamp.ゝ ；≦shi

Claims (1)

[Claims] Defects (4) in through holes (1) of multilayer printed board (6)
) is coated with a fluorescent agent (7), and one end of the through hole is covered with a lid (2), and ultraviolet light irradiated from a lamp (8) provided on the outside of the lid illuminates the fluorescence of the defective part. A through-hole in a multilayer printed board, characterized in that excited fluorescent light generated upon hitting a light agent is received by a light-receiving sensor (5) provided at the other end of the through-hole to detect a defective portion of the through-hole. Inspection method.