JPS61147131A - Insepcting device for through hole - Google Patents

Abstract

PURPOSE:To obtain an inspecting device which has the X-Y stage of simple constitution by providing a light source, a photodetecting element, etc., for the defect detection of a through hole only on one surface of a printed board. CONSTITUTION:Then both-surface printed board 1 having through holes 1a-1d, etc., ios movable by the X-Y stage. The rays of light from a light source 3 provided above the printed board 1 is cut off partially by a mark 4 and the rays of light irradiated through a lens 5 is reflected by metal-plated land parts 6a and 6b, but transmitted through the printed board 1 at other parts and absorbed by a light absorbing material 2. Further, there is normally no light reflected in an area 8 where the rays of light is cut off by the mask 4. An image picked up by a TV camera 7, on the other hand, is displayed as an image 9 on a cathode-raty tube and also converted into an electric signal, which is outputted to a control circuit. Then, it is indicated that there is a defect such as a cut if light leaks from a through hole 1b although the light from te light source is cut off by the mask 4.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to double-sided printed boards and multilayer printed boards used in electronic equipment, and particularly to an inspection device for through holes provided in such printed boards. be.

[Prior art]

For double-sided printed boards and multilayer printed boards, for electrical connections between printed wiring on the front and back sides of the board, and between printed wiring on each layer.

Through holes are formed by electrical or chemical plating. Normally, the plating layer of a through hole is not always in good condition, and defects such as cuts and pinholes may occur due to the manufacturing process. It is necessary to check for such defects in advance because these defects impede the connection purpose and impair the reliability of the printed circuit board.

Conventionally, as a method for inspecting defects in such through holes, a roller mask is provided on a printed board with through holes provided therein, and the printed board is irradiated with light while the roller mask is moved on the printed board.

The light transmitted through the through-holes was detected using multiple light-receiving elements installed on the opposite side of the roller mask on a printed board, and defects in the through-holes were detected based on whether there was light leakage.

[While invention tries to solve! I) In the through-hole inspection device as described above.

In order to irradiate light from one side of the printed board and detect light leakage from the other side, optical paths are created on the upper and lower surfaces of the printed board, and through-hole defects are detected.

Therefore, 1. For example, when irradiating light from the bottom surface of a printed board, an X-Y stage or the like is usually provided on the bottom surface of the printed board to move the printed board. It is necessary to consider the structure of
There was a problem that the device became complicated. Furthermore, since the roller mask was constantly moved and inspected, the life of the roller mask was shortened due to friction with the printed circuit board.

In view of the above-mentioned conventional drawbacks, the present invention aims to provide a through-hole inspection device in which a light source, a light receiving element, etc. are provided only on one side of a printed board, and an X-Y stage, etc. can be realized with a simple configuration. This is the purpose.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a through-hole inspection device that detects a defect in the through-hole by detecting a light leakage pattern of a through-hole provided in a printed board, in which one side of the printed board is irradiated with light. a light source, a condensing means located between the 1M light source and the printed board to condense the light from the light source;

a mask means located between the light condensing means and the light source to block a part of the light source; and an imaging means located on the same plane as the light source with respect to the printed board to take an image of reflected light from the printed board. This is achieved by providing a through-hole inspection apparatus characterized by having a control means for detecting and controlling defects in the through-hole from a signal captured by the imaging means.

[For production]

According to the above means, since the light source and the imaging means are provided only on one side of the printed board, the light from the light source is reflected by the printed board, and the reflected light containing defect information of the through holes is provided on the same side as the light source. Since the other surface of the printed board becomes an area through which light does not pass, it has the effect of simplifying the structure of the X-Y stage, etc. on the other surface of the printed board.

[Embodiments of the invention]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

This embodiment uses a television camera (hereinafter referred to as TV camera) as a light receiving element, and FIG. 1 shows a schematic perspective view of this embodiment. In the figure, a light absorbing material 2 is provided on the lower surface of a double-sided printed board (hereinafter referred to as printed board) 1 which has pattern wiring on both sides and has a large number of through holes 1a to 1d. A printed board 1 is configured to be movable on an X-axis and a Y-axis orthogonal to each other by an X-Y stage.

A portion of the light from a light source 3 provided above the printed board 1 is blocked by a mask 4 provided on the light emitting surface of the light source 3, and is irradiated onto the upper surface of the printed board 2 via a lens 5. Of the light irradiated onto the printed board work, the light irradiated onto areas other than the metal-coated lands 5a and 5b is transmitted into the printed board l.

It is absorbed by the light absorbing material 2. Further, the light irradiated onto the land portions 6a and 5b is reflected, and this reflected light is imaged by the lens 7a of the TV camera 7.

On the other hand, in the area 8 on the brightness plate 1 where light is blocked by the mask 4, there is usually no reflected light, and the image captured by the TV camera 7 is displayed as an image 9 via a cathode ray tube.

The image captured by the TV camera 7 is converted into an electrical signal and output to a control circuit 9 provided in a portion not shown.

FIG. 2 is a block diagram of the control circuit, and the image signal which is an electric signal from the TV camera 7 is transmitted to the hole position address section
0, and the hole position address unit 10 detects the center positions (addresses) of many through holes provided on the printed board 1. The detection signal from the hole position address 10 is input to the address adder 11, and the address adder 11 adds the data from the hole pitch address section 12 to which the pitch of each through hole position is input in advance. The address signals added in are input to the comparator 13.

On the other hand, other image signals 9 from the TV camera 7, for example area 8
The image signal when there is light reflected by the light leakage address section 1
4, and the light leakage address section 14 outputs to the comparison section 13 an address signal of the center position of the light leakage pattern detected by the TV camera 7. The comparator 13 compares both input addresses, and when both address signals match, outputs a defect signal to detect 15 that there is a defect in the through hole existing at the matched address (position).

The operation of the through-hole inspection apparatus having the above configuration will be explained using FIG. 3, (b).

FIG. 3(a) shows an image captured by the TV camera 7)
This is a partial list. In the same figure, the X axis,
The Y axis is the X direction, which is the moving direction of the aforementioned X-Y stage;
It is the same as the Y direction. Two through holes la and lb exist in the image 16.

Further, the through holes la and lb are arranged on the A row having the same coordinates on the Y axis, and the light from the light source 3 enters the through holes la and lb, for example.

As shown in FIG. 4(a), since light is absorbed by the light absorbing material 2, no light leakage occurs from the through holes la and lb.

At this time, the reflected signal waveform shown in the figure (bl) is output from the TV camera 7. Therefore, by setting the slice level to B1, the through hole position can be detected. In other words, the image captured in image 16 A signal is output to the hole position address unit 10 to determine the hole center position 2 of the through holes la and lb, for example.

(Xyu, y(1) (xi), yshi) is detected.

Next, the printed board 1 is moved in the direction of arrow 17 by driving the X-Y stage 1'. During this movement, the image of the printed board 1 is constantly checked by the TV camera 7, and this image signal is output to the light leakage address section 14. An image 18 when the through holes la and lb arranged in row A are moved by a distance MP is shown in FIG. 3).

This moving path MIp is formed in advance by the hole pitch address section 1 described above.
It is equal to the data input in 2. Therefore, the image of the printed board 1 is input to the light leakage address section 14, and if there is light leakage in the through hole 1b at this time, the address of this light leakage is output to the comparison section 13.

This light leakage from the through hole 1b is light that leaks even though the light from the light source is blocked by the mask 4.
As shown in the figure, there is a defect in the through hole 1b with a cut 19.

On the other hand, the comparator 13 uses the address signal of the through hole 1b read in the image 16 described above to match the pitch p between the through holes.
The address signal to which the data of
Defect b can be detected. At this time, the address (coordinate position) of the defective through hole 1b may be displayed externally from the light leakage address section 14.

Further, while the through holes la and lb in the A row are moving, light may leak from, for example, a portion of the printed board 1 where no pattern wiring is provided. The image signal including this light leakage is also input to the light leakage address section 14, and from the light leakage address section 14 this portion 20 is inputted.
The address signal is also input to the comparator 13, but since the address does not have a through hole, the address signal is input to the address adder 11.
The defect detection signal is not outputted if light leaks outside the position where the through hole exists because the address signal input from the through hole does not match.

Next, the X-Y stage 1' is further driven to move the printed board 1 by 1 bit. Defect inspection can be performed on all through holes.

As described above, according to this embodiment, the upper surface of the printed board 1 is irradiated with light through the mask 4, and the light leaked from the through holes la and lb of the printed board 1 is transmitted to one TV camera 7.
It is possible to take an image with

FIG. 6 is a schematic perspective view showing another embodiment of the present invention.

In this figure, the same parts as in FIG. 1 are given the same numbers, and the explanation of the structure will be omitted.

In the figure, the difference from FIG. 1 is that two light sources are provided, and the mask 22 provided below the light source 21 is
It is larger than the mask 4 shown in the figure.

The size is such that the light irradiated onto the printed board 1 can be blocked by two pitches of through holes, and a slit-shaped mask 24 is provided at the bottom of the light source 23, and the width of the slit of this mask 24 is set on the printed board 1. through hole 1e
-1h land portion 6e.

It is large enough to cover 6f, 6g, or 6h.

Further, the amount of light from the light source 23 is adjusted in advance so that the amount of reflected light from the land portions 68 to 6h is at the same level as the amount of reflected light from the base portion 25 of the printed board 1.

Therefore, the light from the light source 21 partially blocked by the mask 22 is irradiated onto the printed board 1 through the lens 26, creating a dark area 27 on the printed board l.

Here, the light from the light source 23 is masked 24. When the printed board l is irradiated through the lens 28, the area within the dark area 26 is
Light is irradiated only through the mask 24. Figure 7 (a
) is a sectional view taken along line AA in FIG. 6, showing the optical paths of both light beams at this time. The light incident on the printed board 1 is transmitted into the base material part 25, and most of the light is absorbed by the light absorbing material 2, but when there is a break in the plating on the side of the through hole 1g, the light is transmitted into the base material part 25. A part of the light transmitted inside leaks into the through-hole position from the cut and is emitted to the outside as leaked light 30. At this time, if the light leakage slice level of the signal intensity waveform diagram shown in the same figure (bl) in which the image received by the TV camera 7 is converted into an electric signal is 82, the waveform convex portion 31 due to the light leakage 30
By detecting and outputting it to the light leakage address section 14 in FIG.
Defects can be detected by comparing with the address signal from.

On the other hand, in the through hole le and the land portion 60 that are irradiated with the light from the light source 23, the light that enters the through hole le is absorbed by the light absorbing material 2, and the light that is irradiated to the land portion 6e is reflected, and the TV camera The light is received at 7. The amount of light received at this time is approximately equal to the amount of light reflected by the base material 25 because the amount of light from the light source 23 is adjusted in advance.If the hole position slice level is C, only the through hole 1e will be in the shadow. The light is received by the camera 7. As described above, according to the present embodiment, it is possible to detect the position of the through hole in the region 29 where the printed board l is irradiated with the light from the light source 23 through the slit portion of the mask 24.

The light source 23 can control the amount of light reflected from the land portion 6e. Therefore, the difference between the amount of reflected light from the base portion 25 and the amount of reflected light from the land portion 6 can be reduced, and the range of the TV camera 7 can be reduced.

FIG. 8 is a diagram showing a second alternative embodiment of the present invention, in which the same parts as in FIG. 1 are given the same numbers and explanations on the structure will be omitted.

The difference between this figure and FIG. 1 is that two TV cameras are used. In this case, from light source 3 to mask 4
The reflected light of the light irradiated onto the printed board 32 through the lens 5 is received by the TV cameras 33 and 34. In particular, when the printed board 32 is thin, as shown in FIG. 9, leaked light from the plating cuts 36 of the through holes 35 can be directly received by the TV cameras 33 and 34, improving the accuracy of light reception.

As explained above, according to the present invention, by providing one or more light sources and a TV camera etc. on one surface of the printed board l, the X-Y stage 1' etc. provided on the lower surface of the printed board l can be structure can be easily constructed. In addition, when detecting the position of the through hole,
A slice level B3 shown in FIG. 10 is provided, the land portion and the through hole portion are detected, and the lengths of the orthogonal shapes are measured using the length measurement sensors 39a and 39b as shown in FIGS. 10(a) and 10(b). , it is also possible to find the through hole position.

For example, the coordinate positions of four points on the outer periphery of the through hole 37 measured by the length measurement sensors 39a and 39b are (xl).

0), (X2.O), (0,37+), (
0, y2), the center 38 of the through hole 37
is ((x + +x 2) /2. (y I+72)
/2).

The embodiment of the present invention is not limited to the above, but as shown in FIG. Even when light is received, the same effect as that of the other embodiment shown in FIG. 6 can be achieved.

Furthermore, the light receiving element used in the present invention is not limited to the TV camera 7,
A two-dimensional light receiving element can be used similarly. Further, when the through holes provided in the printed board 1 are provided at arbitrary positions, a means is provided to detect the hole pitch of the through holes in advance and input this detected data to the hole pitch address section 12. Good too.

〔Effect of the invention〕

As explained in detail above, according to the present invention, when inspecting defects such as breaks in the metal plating of through holes provided on a printed board, pinholes, etc., by providing an optical device only on one side of the printed board, The X-Y stage and the like can be easily configured, and a through-hole inspection device can be easily designed.

winter Also, by using multiple light sources, masks, etc.

Alternatively, by using masks with different transmittances, it is possible to reduce the range of light receiving elements of a TV camera or the like.

Furthermore, the mask does not move on the printed board,
It can be used for a long time.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a through-hole inspection device of the present invention. FIG. 2 is a circuit block diagram of the through-hole device. FIG. 3 is a block diagram of a TV image, and FIG. 4(a) is a block diagram of light leakage. FIG. 4(b) is a characteristic diagram of the reflected signal. FIG. 5 is a cross-sectional view of a part of the printed board. FIG. 6 is a schematic perspective view of a through-hole inspection device according to another embodiment of the present invention. FIG. 7(a) is a sectional view of a part of the printed board. FIG. 8 is a schematic perspective view of a through-hole inspection device according to a second alternative embodiment of the present invention. FIG. 9 is a cross-sectional view of a part of the printed board. FIGS. 10(a) and 10(b) are configuration diagrams illustrating a method for measuring the center of a through hole. FIG. 11 is a schematic perspective view of the through-hole inspection device of the present invention. 1.32...Printed board. la ~ ld, 31 -- through hole. 1'...X-Y stage. 2...Light absorbing material. 3.21.23...Light source. 4.22.24...Mask. 5.26.28...Lens. 6a to 6d...Land portion. 7.33. 34...TV camera. 8...Area. 10... Hole position address. 11... Address addition section. 12... Hole pitch address section. 13... Comparison section. 14...Light leakage address section. 16.18...Image. 19... cut. 25...Base material part. 111th (G) 4th field 156! ! Fig. 6B2 Fig. 8wA Fig. 9 Fig. 10 (b)

Claims (2)

[Claims] (1) A through-hole inspection device that detects a light leakage pattern of a through-hole provided in a printed board to detect defects in the through-hole, which includes a light source that irradiates light onto one side of the printed board, and a light source that irradiates light onto one side of the printed board; a light condensing means located between the boards to condense the light from the light source; a mask means located between the condensing means and the light source to block a part of the light source; A through hole characterized in that it has an imaging means located on the same plane as the light source and takes an image of reflected light from the printed board, and a control means that detects and controls defects in the through hole from a signal taken by the imaging means. Inspection equipment. (2) The through-hole inspection device according to claim 1, further comprising detection means for detecting the through-hole position and the center position of the light leakage pattern.