JPH049251B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] A through-hole for inspecting defects such as pinholes that occur in the conductive layer of an electrical member in which a through-hole is formed in a transparent substrate with a conductive layer formed on the inner wall surface. Regarding the inspection method and its equipment, the purpose is to speed up defect inspection by automatically acquiring through-hole position indication signals and defect indication signals, in addition to being able to perform light shielding of through holes at high speed. When detecting defects in the conductive layer of an electrical member in which a through hole with a conductive layer formed on the inner wall surface is formed in a transparent substrate, the electrical member is illuminated from one side, and the contact between the electrical member and the electrical member is detected. A light-blocking means for blocking the illumination light is disposed on the illumination side while allowing relative movement between the two, and the through-hole to be detected is in a non-light-blocking state by the light-blocking means;
In response to the light shielding state, a through-hole position indication signal and a defect indication signal are respectively generated from a detection system disposed on the opposite side to the illumination side, and in response to these two signals, a defect in the through-hole to be detected is detected. It is configured to detect the presence or absence of.

[Industrial application field]

The present invention relates to a through-hole inspection method and apparatus for inspecting defects such as pinholes that occur in the conductive layer of an electrical member in which a through-hole is formed in a light-transmitting substrate with a conductive layer formed on the inner wall surface.

For screen printed boards and multilayer printed boards, between the front and back printed wiring formed on those boards,
Through holes are formed by electrically or chemically plating for electrical connection between printed wiring layers.

The plating layer of the through hole is not always in good condition, and defects such as cuts and pinholes may occur.

It is necessary to check for such defects beforehand, since they will defeat the purpose of the connection and reduce the reliability of the printed circuit board.

[Conventional technology]

As one of the through-hole inspection methods, a light-shielding mask is closely attached to one side of the through-hole in a printed board, and light is injected into the transparent substrate of the printed board to detect defects that may occur in the plating layer of the through-hole. There is a known method for detecting the presence of defects in the plating layer by detecting the light that passes through the plating layer.

[Problems to be Solved by the Invention] Since this method requires the light-shielding mask to be in close contact with the printed board, it not only makes it impossible to perform prompt inspection, but also makes it difficult to inspect the mask and through-holes for each printed board. There is a problem that alignment must be performed.

The present invention has been created in view of the drawbacks of the conventional methods as described above, and in addition to being able to quickly block light through holes, it also allows automatic transmission of through hole position indicating signals and defect indicating signals. The purpose of the present invention is to provide a through-hole inspection method and device that can speed up defect inspection by acquiring accurate information.

[Means for solving problems]

A first aspect of the present invention is to illuminate the electrical member from one side when detecting defects in the electrically conductive layer in which a through hole is formed in the transparent substrate and the electrically conductive layer is formed on the inner wall surface of the electrical member. , disposing a light-shielding means for blocking the illumination light on the illumination side while allowing relative movement between the electric member and the through-hole to be detected by the light-shielding means; In response to the light shielding state, a through-hole position indication signal and a defect indication signal are respectively generated from a detection system disposed on the opposite side to the illumination side, and in response to these two signals, a defect in the through-hole to be detected is detected. It is configured to detect the presence or absence of.

A second aspect of the present invention is to form a through hole in which a conductive layer is formed on the entire inner wall surface of a transparent substrate, and to generate electricity that moves in a predetermined direction within a plane including the transparent substrate. A through-hole inspection device for detecting defects in the conductive layer of a member, comprising: a light source illuminating the electrical member; and light from the light source entering the through-hole to be inspected while allowing the movement of the electrical member. a through-hole position detection means that outputs a position indication signal of the through-hole to be inspected in a state where the masking means does not block the light from the light source from entering the through-hole to be inspected; Detecting the presence of light from the light source injected into the transparent substrate of the electrical member in the through hole in a state where the mask means blocks the light from the light source into the through hole to be inspected. , comprising a defect detection means for outputting a through-hole defect indication signal, and means for determining the presence of a defective conductive layer from the position indication signal from the through-hole position detection means and the defect indication signal from the defect detection means. It is composed of

[Effect]

In through-hole inspection, an electrical component is illuminated by a light source from one side, and the through-hole to be inspected in the electrical component is inspected in a state where the light from the light source is not blocked by a means capable of blocking light. A through-hole position display signal of the target through-hole is output from a detection system (or through-hole position detection system) that detects light from the light source that has passed through the target through-hole.

Furthermore, in a state where the through-hole to be inspected is blocking light from the light source by a light-shielding means, the light from the light source injected into the transparent substrate is transmitted when there is a defective part in the through-hole to be inspected. If there is, the light passes through this and enters the through hole to be inspected, and the light is detected by a detection system (or defect detection means) and a defect display signal is output.

Based on this defect display signal and the through-hole position display signal, the determining means recognizes that there is a defect in the through-hole to be inspected.

〔Example〕

FIG. 1 shows a first embodiment of the present invention.
In this figure, 1 has a conductive layer 3 on a transparent substrate 2.
An electrical member (hereinafter simply referred to as a printed board) in which a through hole 4 is formed on the inner wall surface.
shows. Reference numeral 5 denotes a light shielding means (hereinafter simply referred to as a mask), which shields the printed board 1 on the illumination side of the printed board 1 (6 represents the oblique illumination light).
It is located at a predetermined distance, for example, about 0.1 mm, from the center. 7 is a lens constituting the optical system, and 8 is a photodetector.

According to this configuration, the oblique illumination light 6 is transmitted through the mask 5.
If there is a defect in the conductive layer 3, the light that has been injected into the transparent substrate 2 and propagated will be transmitted from the defect 9 to the through hole 4. Leak inside. By detecting the light through the lens 7 with the photodetector 8, it can be determined that a defect has occurred in the conductive layer 3 of the through hole 4.

According to this inspection method, a means is provided that allows relative movement between the mask 5, etc. and the printed board 1 as soon as possible after the inspection, so the inspection can be speeded up. It can make a lot of progress. Also, oblique illumination introduces advantages in inspection and is therefore preferred. 6' is also an oblique illumination light symmetrical to illumination light 6,
By using this illumination light in combination, even illumination can be achieved.

Note that although FIG. 1 shows a diagram in which light leaking from a defect 9 into the through hole 4 is detected by the photodetector 8 via the lens 7, as also described in FIGS. 2 to 6, Through hole 4P
The light from the two through-hole positions of the through-hole 4A is transmitted through the half mirror 1 with one lens 12.
3, the light is focused and imaged onto photodetectors 14 and 15, respectively.

FIG. 2 shows a first embodiment of the second aspect of the present invention. In this figure, 1, 5, and 6 are the same as explained in FIG. 10 is controller 1
This stage is driven and controlled by 1. 1
Reference numerals 2 and 13 are lenses and half mirrors that constitute the optical system, respectively. 14 and 15 are photodetectors;
14 is for detecting direct light from a preceding through hole (through hole outside the mask) in the direction of movement of the printed board 1 by the stage;
Further, 15 is for detecting light from the through hole in which the mask 5 is positioned.

These photodetectors 14 and 15 are both composed of well-known line CCDs,
This line CCD is arranged perpendicularly to the direction of movement of the printed board 1 and is configured to generate, for example, eight analog pixel signals. The photodetectors 14 and 15 generate eight analog pixel signals every time the printed board 1 moves a predetermined unit distance. The number of the eight pixel signal generation cells of the photodetectors 14 and 15 is determined by the shift register 18, which will be described later.
This corresponds to 8 shift positions for each stage of 19 stages.

These photodetectors are connected to shift registers 18 and 19 via corresponding binarization circuits 16 and 17, respectively. The shift registers 18 and 19 are configured to have a capacity capable of accommodating an area corresponding to the positional difference detected by the photodetectors 14 and 15.

18 and 19 in FIG. 2 are shift registers.
In the shift register 18, the binary image signal input to the upper left signal input is sequentially shifted to the right for each clock pulse, and the signal shifted out from the rightmost end of the top stage of the shift register 18 is shifted in to the next stage. . In the other stages, the binary image signals are sequentially shifted in the same way. At this time, the images appear to be sequentially moved to the right.

This relationship for shift register 18 also applies to shift register 19 as well. However, the shift register 18 and the shift register 19 are different in size. That is, shift register 1 in FIG.
8 has five stages, whereas shift register 1
9 has three stages. This difference in the number of stages is set as follows. In FIG. 2, when the printed board is moved at a constant speed, the time it takes to move from the through hole detection position 4P for the through hole to be inspected to the defect position detection position 4A for the through hole to be inspected is determined by the configuration of the device. Since this can be known in advance from above, the shift positions passing through the shift register 18 are increased by this amount of time. As a result, the through-hole detection image taken at the through-hole detection position 4P and the through-hole defect detection image taken at the defect position detection 4A are respectively transferred to the shift register 1.
8, and can be sequentially moved to the right while maintaining its position in the shift register 19.

Positionally corresponding partial outputs A, regarding the printed board 1 in these shift registers 18 and 19,
Of B and C, A and B are connected to an AND gate 20, and C is connected to an AND gate 21, and the outputs of these AND gates 20 and 21 are connected to the controller 11 via an AND gate 22.

A and B of the shift register 18 are binary image signal take-out shift positions, and these take-out shift positions may be arbitrary positions within the area where the binary image signal in the shift register 18 moves from left to right.
The take-out shift position A corresponds to the hole of the through-hole, and when there is a through-hole position display signal, the binary signal becomes "1", while the take-out shift position B corresponds to the periphery of the through hole.
When the through-hole position display signal is a binary signal "1", the peripheral signal B becomes a binary signal "0". C of the shift register 19 is a shift position for taking out a defect display signal in the binary image signal format;
It is set to correspond to the take-out shift position A in the shift operation. The defect display signal extraction shift position C is such that when there is a defect at the corresponding position in the through hole, the defect detection signal C is a binary signal "1".
Therefore, when there is no defect, the defect detection signal C becomes a binary signal "0". Therefore, if there is a defect in the through-hole to be inspected, the through-hole position detection signal for the through-hole to be inspected is a binary signal "1", the peripheral peripheral signal B is a binary signal "0", and the defect detection signal is Since signal C becomes a binary signal “1”,
The AND output of the AND gate 22 becomes a binary signal "1", indicating that there is a defect in the through hole to be inspected.

To explain the operation of this first embodiment, while illuminating the lower side of the printed board 1 with oblique illumination light 6, the stage 10 is moved in a predetermined direction under the control of the controller 11, e.g. direction. At that time, for example, the position of the through hole 4P is detected by a detection system consisting of a lens 12, a half mirror 13, and a photodetector 14, and the direct light from there is detected, and an analog through hole position indicating signal is obtained. is binarized by the binarization circuit 16 and sent to the shift register 18 in synchronization with the above-mentioned movement.

When the movement of the stage 10 progresses and the above-mentioned through hole 4A comes to be detected by the detection system consisting of the lens 12 and the photodetector 15, the presence or absence of defects that may occur in the conductive layer of the through hole 4A is detected. A defect indication signal is generated representing the defect. This signal is binarized by the binarization circuit 17 and sent to the shift register 19 in synchronization with the above-mentioned movement.

The defect display signal sent to the shift register 19 appears at a predetermined output of the shift register 19 when the sending is completed or after a predetermined time has elapsed, but at that time, it is sent to the shift register 18 in advance. A through hole position indication signal also appears at a predetermined output of shift register 18. That is, when the printed board is moved at a constant speed, a through-hole position display signal for the through-hole to be inspected is obtained via the photodetector 14 and the binarization circuit 16, and the photodetector 15 and the binarization circuit 17. The defect detection signal for the through-hole to be inspected obtained through this process is output with a time difference as described above. When both of these signals are input to the shift register 18 and shift register 19 configured as described above, a through hole display position signal for the through hole to be inspected is output from these shift registers 18 and 19, It is possible to take out the defect indication signal at the same time. These output relationships are shown diagrammatically in FIG. 2 (see A, B, and C in FIG. 2).

Among these outputs A, B, and C, A and B supply a through hole position indication signal to the AND gate 20, while C supplies a defect indication signal to the AND gate 21.
A defect detection signal indicating whether or not there is a defect in the conductive layer of the through hole is generated from the AND gate 22, and this signal is supplied to the controller 11 for controlling the next process.

Such defect inspection can be performed continuously on subsequent through-holes without the need to perform any operations on the mask 5. As above, the first
This invention is utilized as one aspect in this embodiment.

Further, in this embodiment, mask alignment is automatically performed, helping to speed up the above-mentioned continuous inspection.

FIG. 3 shows a second embodiment of the second invention of the present invention (also an embodiment of the first invention), and this embodiment shows the separation of the mask 5 from the printed board 1 (the third embodiment).
A through hole position indicating signal is obtained when the mask 5 approaches the printed board 1 (see 3-2 in FIG. 3), and a defect indicating signal is obtained when the mask 5 approaches the printed board 1 (see 3-2 in FIG. 3). That is, the illumination light 6 that has been unblocked by the mask 5 passes through the through hole 4, is focused by the lens 23, is received by the TV camera 24, and is converted into an electrical signal. The signal is binarized by the binarization circuit 25 and stored in the pattern memory 26 as a through-hole position display signal. After that, the mask 5 is brought close to the printed board 1, and the light that reaches the through holes 4 is no longer direct, but only light from defects that may occur in the conductive layer of the through holes 4. Therefore, only when this light is present, a defect display signal is supplied to one input of the AND gate 27 via the lens 23, the TV camera 24, and the binarization circuit 25, and the through hole read from the pattern memory 26 is supplied. A position indication signal is provided to the other input of AND gate 27.
In this way, the defect detection signal is
Output from 7.

As is clear from the above description, the effect can be comparable to that of the first embodiment.

FIG. 4 shows a third embodiment of the second invention of the present invention (also an embodiment of the first invention). There is no difference from the second embodiment except that . The reference numerals of the embodiment in FIG. 3 are also used for its constituent elements, and their explanations are omitted.

Further, the effect is the same as that of the second embodiment except that the speed of inspection is improved.

FIG. 5 shows the main part of a fourth embodiment (also the main part of the embodiment of the first invention) which is different in that the mask 5 is replaced with a cylindrical rotating mask 29, and FIG. The main part of a fifth embodiment (also the main part of the embodiment of the first invention) is shown, which is different in that a rotating plate mask 30 is used. There is basically no change in its action and effect.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, high-speed inspection can be performed, defect detection and fixing of the defect position can be automatically performed, and the speed of defect inspection can be promoted. Effects such as continuous implementation of the test can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention;
2, 3, 4, 5, and 6 respectively show the first embodiment, second embodiment, third embodiment, and third embodiment of the second invention of the present invention. Main part of the example of 4,
and FIG. 7 is a diagram showing the main parts of the fifth embodiment. In FIGS. 1 to 6, 1 is a printed board;
2 is a transparent substrate, 3 is a conductive layer, 4 is a through hole, 5, 28, 29, 30 is a mask, 10 is a stage, 11 is a controller, 7, 12, 23 is a lens, 8, 14, 15 is a light Detector, 16, 17,
25 is a binarization circuit, 18 and 19 are shift registers, and 20, 21, 22, and 27 are AND gates.

Claims (1)

[Scope of Claims] 1. When detecting a defect in a conductive layer of an electrical member in which a through-hole is formed in a light-transmitting substrate and a conductive layer is formed on the inner wall surface, the electrical member is illuminated from one side thereof. and disposing a light-shielding means for blocking the illumination light on the illumination side while allowing relative movement between the electrical member and the through-hole to be detected by the light-shielding means. , a through-hole position indication signal and a defect indication signal are generated from a detection system disposed on the opposite side to the illumination side, respectively, in response to the light-shielded state, and in response to these two signals, the detection of the through-hole to be detected is performed. A through-hole detection method characterized by detecting the presence or absence of defects. 2. The detection system generates the through-hole position indication signal and the defect indication in response to a relative substantially parallel movement between the electric member and the light-shielding means at least at the position of the detection target through-hole in the electric member. A through-hole inspection method according to claim 1, characterized in that a signal is generated. 3. The detection system according to claim 1, wherein the detection system generates the through-hole position indication signal and the defect indication signal in response to separation and proximity of the electric member and the light-shielding means. Through-hole inspection method. 4. The through-hole inspection method according to claim 1, wherein the means capable of blocking light is a liquid crystal means. 5. A through hole in which a conductive layer is formed on the entire inner wall surface is formed in a light-transmitting substrate, and the conductive layer of an electric member is capable of causing movement in a predetermined direction within a plane that includes the light-transmitting substrate. A through-hole inspection device for detecting defects in a through-hole, comprising: a light source that illuminates the electrical member; and a light source that blocks light from the light source from directly entering the through-hole to be inspected while allowing the movement of the electrical member. through-hole position detection means for outputting a position display signal of the through-hole to be inspected in a state in which the masking means does not block light from the light source to the through-hole to be inspected; detecting the presence of light from the light source injected into the transparent substrate of the electrical member in the through hole in a state that causes the light from the light source to be blocked from entering the target through hole;
Defect detection means for outputting a through-hole defect indication signal; and means for determining the presence of a defective conductive layer from the position indication signal from the through-hole position detection means and the defect indication signal from the defect detection means. A through-hole inspection device featuring: