JPS5999364A - Through hole inspector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (11) Technical Field of the Invention The present invention relates to a through-hole inspection apparatus that obtains an image of a through-hole defect and uses the image to determine a through-hole defect.

(2) Background of the technology A large number of through holes are formed in a printed circuit board, and it is essential to improve reliability that the conductive layer of the through holes be free of defects.

However, depending on the degree of the defect, even if it exists, it may be acceptable. However, conventional devices have no way of making this determination, and the detected defect renders the printed circuit board unusable.

The development of technical means that can solve these problems has been eagerly awaited.

(3) Prior Art and Problems In the conventional device, there was only a choice between whether there was a defect in the through hole or not. Therefore, even if the defect is such that the through-hole function is not lost, the printed circuit board is determined to be defective, and the printed circuit board is excluded from effective use of the printed circuit board. .

(4) Purpose of the Invention The present invention was devised in view of the drawbacks of the conventional device as described above, and its purpose is to provide a through hole that can determine the defect shape and contribute to the effective use of items with acceptable defects. The purpose is to provide inspection equipment.

(5) Structure of the Invention The object of the present invention is to provide a through-pole inspection device for an electrical member having a through-hole with a conductive layer formed on the inner wall surface, and to provide an illumination means for injecting light into the outer periphery of the conductive layer of the through-hole. , a light shielding means for shielding one end of the through hole from light, an image signal generating means for generating an image signal of a defective optical image that may be generated on the inner surface of the through hole via the other end of the through hole, and the image signal. This is accomplished by providing detection means for detecting defects in the conductive layer in response to.

(6) Embodiments of the Invention The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the invention. In this figure, 1 is a printed circuit board with a conductive layer (copper foil) on the inner wall surface 2.
3 (hereinafter referred to as an electrical member having a through pole 4 formed with
The printed board will be explained. ). Reference numeral 5 indicates light incident on the outer periphery of the No. i1 foil in the through hole 4, and this light is generated from an illumination means (not shown).

Reference numeral 6 denotes an optical system including, for example, one lens 7 as shown, which is used to combine a light image generated by a defect 8 that may occur in the copper foil 3 onto an imaging surface. Reference numeral 10 denotes a light shielding means, and for example, a light mask is used to block the light 5 from the illumination means from entering the inside of the through hole from one end thereof.

A plurality of photodetectors 11 as converting means are arranged on the image forming plane. This photodetector is configured to be movable up and down with respect to the drawing along with the lens 7.

12 is a lens 7 so as to allow light to enter the lens 7;
and a cover surrounding the photodetector 11, which is provided as necessary.

Photodetector 11 is connected to detection means 13 .

This detection means includes a binarization circuit 14 connected to each output of the photodetector 11, and an adder circuit device 15 connected to the output of the circuit 14 so as to generate a sum of the output values. (15, 15□ . . . are adder circuits.), the output of the adder circuit device 15 is connected to one input, and the output of a reference value generation circuit (not shown) is connected to the other input. and a comparator circuit 16.

Next, the operation of the apparatus of the present invention having the above-described configuration will be explained.

When the illumination means makes light enter the outer periphery of the through hole 4 to be inspected, if there is a defect in the copper foil 3 of the through hole, that is, a defective good part 8, the light will pass through that and enter the through hole 4. Leak.

Assuming that this light is exactly at the position where it is imaged by the lens 7 on its imaging plane, the light image will be imaged on the photodetector ll arranged on the imaging plane.

If the above-mentioned defect is as shown in FIG. 2, that is, there is a stuck good part 8 only in a part of the circumference of the through hole, the optical image will be a part of the photodetector 11 arranged in a ring shape. It only appears as a bright area. Also, as shown in Figure 3, the defect is all over the circumference! If the light is on, all the photodetectors 11 will be illuminated.

An output signal is generated from the brightly illuminated photodetectors 11, which is binarized by the binarization circuit 14, and the number of photodetectors 11 that have detected strong light is summed by the addition circuit device 15. , and its value is compared with a reference value by a comparison circuit 16.

The comparison result indicates whether the inspected defect is acceptable (see FIG. 2) or unacceptable (see FIG. 3).

Also, no matter where there is a defect in the through hole 4, the lens 7
By moving the photodetector 11 up and down, the above-described defect detection can be performed.

FIG. 4 shows a second embodiment of the invention.

This embodiment differs from the first embodiment in that a two-dimensional scanning means 17 such as a TV camera or a COD sensor is used as a conversion means, and the detection means 13 is changed accordingly. . Since the other components are the same as those in the first embodiment, the same reference numerals are given to the same components and the explanation thereof will be omitted.

The detection means of this embodiment connects a binarization circuit 18 to the output of a TV camera 17, captures the output signal of the circuit 18 into an image memory 20 under the control of a memory control circuit 19, and after completion of the process, the memory control circuit 19 Image memory 2 under the control of
Each pixel signal of 0 is read out to a counter circuit 21, and the counter circuit 21 counts this and compares the obtained value with a reference value.

The general operation of the embodiment shown in FIG. 4 is the same as that of the first embodiment, differing only in its details, and the effects obtained therefrom are also the same as those of the first embodiment.

In the above embodiment, a case has been described in which the optical system 6 and the converting means 11 are placed near and far from the printed board l, but the configuration may be reversed. Further, the optical system may be a zoom mechanism.

(7) Effects of the Invention As is clear from the above description, according to the present invention, defects occurring in through balls can be classified into tolerable defects and non-tolerable defects. Therefore, the yield of printed boards etc. can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIGS. 2 and 3 are diagrams used to explain the first embodiment, and FIG. 4 is a diagram showing a second embodiment of the present invention. It is a diagram. In the figure, 1 is a printed board, 2 is an inner wall surface, 3 is a conductive layer, 4 is a through ball, 5 is incident light, 6 is an optical system, 8 is a defect, 1
1 is a photodetector (conversion means), 10 is a light shielding means, and 13 is a detection means. Patent applicant Fujitsu Ltd. Figure 2 Figure 3

Claims (5)

[Claims] (1) A through-hole inspection device for an electrical member having a through-hole with a conductive layer formed on an inner wall surface, comprising: illumination means for making light enter the outer periphery of the conductive layer of the through-hole; and one end of the through-hole. a light shielding means for shielding light from the through hole; an image signal generating means for generating an image signal of a defective light that may be generated on the inner surface of the through hole through the other end thereof; and an image signal generating means for generating an image signal of the conductive layer in response to the image signal. 1. A through-hole inspection device comprising: a detection means for detecting a defect in the through-hole inspection device. (2) The image signal generating means includes an optical system that forms a defect optical image that may be generated on the inner surface of the through hole through the other end of the through hole, and an optical system that forms a defect optical image on the image forming surface. 2. The through-hole inspection apparatus according to claim 1, comprising a converting means for converting into an electric signal, and a driving means for moving the optical system, the converting means, and the electric member relatively close to each other. (3) The image signal generating means includes a zoom type optical system that images a defective light image that may be generated on the inner surface of the through hole through the other end of the through hole, and a defective light image on the image forming surface. 2. The through-hole inspection apparatus according to claim 1, further comprising conversion means for converting an image into an electrical signal. (4) The through-ball inspection device according to claim 2 or 3, wherein the converting means comprises a plurality of photodetectors arranged on the imaging plane. (5) The through-hole inspection apparatus according to claim 2 or 3, wherein the converting means is a two-dimensional scanning means.