JPS59126234A - Printed board through-hole inspection equipment - 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 (1) 9 Technical Field of the Invention The present invention relates to a through-hole measuring device for optically detecting defects such as pinholes formed on the inner wall of a through-hole in a printed circuit board, and particularly relates to a through-hole measuring device for optically detecting defects such as pinholes formed on the inner wall of a through-hole in a printed circuit board. The present invention relates to a through-hole inspection device for a printed board that detects defects in the inner wall of the through-hole by using a mask that blocks light from one end and light that is irradiated onto the printed board.

(2) Background of the Technology Through-hole plating is widely used to connect front and back conductors of double-sided printed boards or to connect interlayer conductors of multilayer printed boards. This through-hole plating method involves drilling holes in an insulating substrate laminated with conductors in advance, and
Electrical connection between conductors is achieved by chemically or electrically forming a plating layer on the inner wall surface of the hole. Due to the severe unevenness and small diameter of the through-holes, defects such as holes and cuts often occur in the plating layer, and if the defective part of Metsukino V is thick, it may cause an electrical failure of 4m between the conductors. It becomes a big problem in terms of connection and 1g compliance of the printed board. Therefore, it is desired to be able to easily and reliably inspect such defects in through holes. At least one of the through-holes to be inspected is covered with a circular mask, and the insulating substrate located around the through-hole blocked by the mask is partially illuminated. When light leaks into the through-hole through a defect in the plating of the through-hole, this is detected by a light detection means, or the inside of the through-hole is imaged by a television camera, and the defect is detected by a monitor television or defect recognition means. There is a method that determines M/N/7.

However, with the former method, the mask must be positioned and set around the through-hole in contact with the printed board, which poses a problem when performing through-hole inspection at high speed. Transverse force of through-hole (although it is possible, the through-hole diameter is small (0.5+im or less) and long (2 to 3 mm) like in a multilayer board.
(threshold), it becomes virtually impossible to detect defects inside through-holes9.

(4), Purpose of the Invention The invention was made in view of the above-mentioned drawbacks of the prior art, and it is a printed board that enables through-hole inspection at tube speed and high S, and also facilitates light shielding of through-holes during inspection. (5) Structure of the Invention In order to achieve the above object, an uninvented through-hole inspection device for a printed board uses a light for inspection that is irradiated onto one side of the printed board. , a mask means for blocking the light from the horizontally placed light beam from entering the through hole of the printed board directly or in an open manner; The device is equipped with a defect inspection means for detecting the presence or absence of a defect in the through hole based on the presence or absence of light passing into the hole, and a determination system means for optically or electrically observing and determining the position of the through hole. .

(6) Embodiments of the Invention The following describes the embodiments of the present invention with reference to the drawings. , 1 ;
-1: The printed board to be inspected, this printed board 1
The substrate material 2 constituting the is, for example, a light-transmitting V! glass fiber impregnated with Evokin resin. ]lj! i. Consisting of
As shown in FIG. 2, a plating layer 3 is formed on the inner wall of a through hole 2a drilled in the substrate side 2, thereby forming a through hole 4 for electrically connecting the front and back conductors. Such through holes 4 are formed in a matrix at a predetermined pitch on the printed board 1 as shown in FIG. The print slope mounting portion 5a of the Y stage 5 is formed of a transparent material such as glass, and six types of masks 6 are provided around the table installation area of the printed board 1 to block light from entering each through hole 4. has been done. The above-mentioned mask 6 is formed by forming the latex 6b on the fall of the transparent plate 6a in accordance with the arrangement of the through nails 4 as shown in Table 9.
The thickness and size of the light-shielding portion 6b are complementary to the size of the land area 7, and by bringing this light-shielding portion 6b into close contact with the monument from the stage installation surface side of the printed board 1, it is possible to connect the conductor to the inside of the through-hole 4. 8 is a light source for through-hole conditioning arranged on the lower surface side of the X-Y stage 5, and the source of this light from 8 is transmitted by the optical system 9 at the base. The light is focused and illuminates the printed board 1 from the bottom side through the X-Y stage 5 and mask 6. Also, an objective lens 10 is provided on the top side of the printed board 1 facing the light source 8. A light separation filter 11 that transmits the light that has entered the through hole 4 through the defect 3a of the through hole 4 and a television camera that detects the light image that has passed through the light separation filter 11 are arranged after the objective lens 10. Or CCD (Charge Coupled De
A photodetector 12 consisting of a photodetector (vice), etc.
The state is such that it is converted into an electrical signal and applied to the binarization circuit 13. This binarization circuit 13 converts the aperture image of the through hole 4 focused on the detector 12 into a binary signal of 1-1'' or 1-0'' depending on the presence or absence of light leaking into the through hole 4 from the defect 3a. This binarized aperture image of the through hole 4 is stored in the shift register 14. The light source 8, objective lens 10, light separation filter 11, and photodetector 12 constitute a defect detection system 15 for the through hole 4.

Reference numeral 16 denotes a light source for determining the size of the through hole 4, and the light from this light source 16 passes through a condenser lens 17 and a light separation filter 18 that transmits light having a wavelength component different from that of the light separation filter 11. The through hole 4 to be inspected through is irradiated, and
The portion of the through hole 4 (including the land portion) caused by this illumination is imaged by the objective lens 10 and the light separation filter 11 on a photodetector 19 consisting of a television camera, COD, etc., and the optical image is converted into an electrical signal. After that, it is added to the binary 1-hi circuit 20. Keita, above 2
The value conversion circuit 20 converts the optical images of the through hole 4 and the land portion 7 into binary signals of "1" and "1-0".
The converted images of the opening of the through hole 4 and the land portion 7 are stored in the shift register 21. Note that the objective lens 10, the light separation filter 11, and the light source 1
6 and a photodetector 19Ft constitute a system means 22 for determining the position of the through hole 4.

The shift register 14 manually outputs each bit of the area where the opening pattern A of the through hole 4 is stored.
An ND gate 24 is connected, and the logical product output of the AND gate 24 is applied to an AND gate 25 by 7 so that 1 is selected. Further, the shift register 21 has an open pattern A of the through hole 4 as shown in 1. A NAND gate 26 receives as input the output of the valley bit of the one page area to be printed, and an AND gate 27 receives as input the output of the valley bit of the area where the peripheral pattern B of the land portion 7 of the through hole 4 is stored. , the outputs of the NAND gate 26 and the AND gate 27 are fed to the AND gate 28, and the
The output of the ND gate 28 is sent to the AND gate 25.
It is now possible to 1, the output of the AND gate 25 - the control circuit 2 that controls the Y table 5
9 [I'm going to be able to get away with it-C.

Next, the operation of this embodiment configured as described above will be explained.

When inspecting the through holes of the printed board 1, first, the mask 6 is tightly attached to the stage installation surface of the printed board 1 so that each through hole 4 is closed by the light shielding part 6b, and this is placed on the X-Y stage 5. Set to . Then X
- Operate the Y table 5 to index the position so that one of the through holes 4 faces the objective lens 10. When the light source 8 is turned on, the printed board 1 is partially illuminated from below through the condensing optical system 9 and the 70) In this state, the irradiated light from the bottom surface of the printed board enters into the insulating substrate #2 and is diffused, and the diffused light is emitted to the outside from the top surface of the board.

Here, if there is a defect 3a such as a bottle hole in the plating layer 3 of the through hole 4, a part of the light diffused within the insulating substrate material 2 leaks into the through hole 4 through the defect 3a, and the upper surface of the through hole 4 opens. The light is emitted in the direction of the objective lens 10. That is, the inside of the through hole 4 is illuminated by the light from the light source 8. Therefore, the bright light image corresponding to the upper surface opening of the through hole 4 passes through the light separation filter 11 by the objective lens 10 and is focused on the light receiving surface of the photodetector 12, thereby converting the open Lopakuun's yL image into an electrical signal. Then, it is binarized by the binarization circuit 13 and the shift register 14 is made to be unique. At this time, the outputs of each bit in the register area of the opening pattern A of the shift register 14 are all 1-1, which satisfies the logical performance condition of the AND gate 24 which inputs the valley bit output, and its output Set to "1".

On the other hand, when the land portion of the through hole 4 indexed to the inspection position is illuminated by the light source 16 through the condenser lens 17 and the light separation filter 18, the light reflected from the surface of the land portion 7 illuminates the objective lens 10. After passing through, the light is reflected by the light separation filter 11 in the direction of the photodetector 19, and an image is formed on the light receiving surface of the photodetector 19. As a result, the pattern light image of the land portion 7 is converted into an electric signal, which is further binarized by the binarization circuit 20 and stored in the shift register 21. At this time, all the valley bit outputs corresponding to the outer contour part of the land part 7 in the storage area of the land pattern B of the shift register 21 become "1", and the valley bit output of the storage area corresponding to the open pattern A of the through hole 4 becomes "1". All bit outputs are "0". For this reason, the NAND gate 26
The logical conditions for the AND gate 27 are satisfied, and the logical condition for the AND gate 28 is also satisfied so that the outputs of both gates 26 and 27 are made by two people.

As a result, the AND condition of the AND gate 25 which outputs the outputs of the AND gates 24 and 28 is satisfied, and by sending the output to the control circuit 29, it is determined that the through hole 4 is defective. Along with
The position of the defective through hole is recognized, and the spatula indexes and controls the XY stage 5 for inspection of the next through hole 4.

Note that when the objective lens 10 faces the second insulating substrate between the through holes 4, the light from the light source 8 that has passed through the insulating substrate material 2 traces the objective lens 10 and the light separation filter 11 and is detected. detected by the device 12, and 21 the direct conversion circuit 1.
3 is binarized and stored in the shift register 14, and the AND condition of the AND gate 24 is satisfied, but since the detection condition of the through-hole 40 and the 10th stage of positioning judgment thread 22 is not satisfied, It will not be determined that it is a through-hole defect. 1, the position of the objective lens 10 ((If there is no through hole 4 in the indexed land, that is, in the resuscitation barrel body, the position of the objective lens 10 is 6 pins corresponding to the through hole opening lever pattern A of the shift register 21 shown in FIG. Since the valley bit output of the memory area is 11, the output of the NAND gate 26 is held at 0, and the through-hole inspection is disabled.

-1. If there is no through hole, no light from the light source 8 enters the through hole 4, so the image of the through hole aperture focused on the photodetector 12 by the objective lens 10 (is a black background). and i
, 9, 1- for this! I-2 ("4 conversion circuit 13r (by 2 ID conversion δ)", and the data of the through nail opening that is recorded in the soft register 14 is tabulated [0
”.

On the other hand, the light source 1 passes through the condensing lens 17 and the optical filter 18.
The egg pattern data of the through-hole land portion when illuminated by the shift register 21 in FIG.
The result is similar to that shown in , which results in l\AN
The outputs of the D gate 26 and the ANLI gate 27 are "1", but the output of the AND gate 24 is "1-0", so the output of the ANLI gate 25 is set to "0". Therefore, it is determined that the through hole 4 has no defect.

In the case of "Honjirikikenma" configured as above, one opening of the print value 1 is used to block the light to the through hole W7.
A mask 6 is placed on the side to be inspected, and a light beam for detecting through-hole defects is irradiated from the side in close contact with the mask.On the other side of the printed circuit board 1, there is a judgment system for determining the position of the through-hole to be inspected and a through-hole. A defect detection system means for detecting the presence or absence of a defect is provided, and when the detection conditions of both means are satisfied, it is determined that there is a defect, so that high S/
N, high-speed inspection is possible, and
The structure for through-hole inspection also becomes simpler.

FIG. 4 shows another embodiment of the through-hole inspection apparatus of the present invention, and particularly shows a modification of the through-hole light shielding means. In the figure, 30 is a light source 8 for through-hole inspection.
' is a mask placed in front of the light irradiation part, and this mask 3
0 has at least one light-shielding pattern 31 corresponding to the formation of the through-hole 4 and land portion (copper foil) 7 formed on the printed board 1, and the front part of the mask 30 faces the light-shielding pattern 31. A convex lens 32 is placed in the shading pattern 31! An image is formed on the surface of the printed board 1 where the through hole 4 is formed, and this
The through hole 4 is further shielded from light from the light source 8. Further, on the side of the printed board 1 opposite to the side where the light source 8 is installed, there is a photodetector 13 that faces the through hole 4 and detects light 33 leaking from the defect 3a of the through hole 4;
Although not shown, it goes without saying that a detection system means 15 and a through-hole position determination system 22 similar to those shown in FIG. 1 are installed.

In such an embodiment, there is no need to bring the mask 30 into close contact with the printed board 1, so there is no risk of damaging or staining the mask 30, and the mask can be used semi-permanently. Even if the pitch, size, etc. of the through holes formed in the printed board 1 change, there is an effect that can be used for all. Further, by changing the position of the lens 32 or the mask 30 in the optical axis direction, the light shielding area for the through hole 4 can be arbitrarily set without changing the mask 30.

In the embodiment shown in FIG. 4, the convex lens 32 may be replaced with a concave mirror. In this case, the light source 8 and mask 30 will be placed inside the concave mirror.

(7) As described in detail in 6 of the invention, the through-hole inspection apparatus of the present invention uses a mask to prevent light from the defect inspection light source that is irradiated onto one surface of the printed board from entering the through-holes. On the other side of the printed board, there is a defect detection system that detects the presence or absence of a defect in the through hole based on the presence or absence of transmitted light into the through hole, and an optical system that detects the position of the through hole. and a determination system for electrically determining, and when the detection conditions of both systems are met, it is determined that there is a defect in the through hole. There are no obstacles in the way, which makes high-speed inspection possible, and through-hole inspection with high S/H is possible9.The structure of the through-hole light shielding means can also be easily constructed.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an example of a through-hole inspection device for a printed board according to the present invention, FIG. 2 is a sectional view of a through-hole portion of a printed board according to the present invention, and FIG. 3 is an example of a mask according to the present invention. The partially perspective view shown in FIG. 4 is another embodiment of the through-hole light shielding means of the present invention. FIG. Explanation of symbols In the drawings, 1 is a printed board, 2 is an insulating substrate material, 3 is a plating layer, 3a is a defect, 4 is a through hole, and 5 is an X-Y
Stage, 6 and 30 are masks, 6b and 31 are optical parts, 7 is a land part (conductor group), 8 is a light source for inspection, 9 is a condensing optical system, 10 is an objective lens, 11.18 is an original separation filter , 12.19 is a nine-inspection J, D device, 13.20 is a double darkening circuit, 14.21 is a shift register, 15 is a through-hole defect detection system means, and 22 is a through-hole position determination system means. Patent applicant Fujitsu Stock Exchange Co., Ltd.

Claims (3)

[Claims] (1) The inspection source that illuminates one side of the printed board is connected directly or li, tj directly so that the light from this horizontal light source does not enter the through holes of the printed board. a mask means, a defect detection means disposed on the other side of the printed board for detecting the presence or absence of a defect in the through ball based on the presence or absence of transmitted light into the through hole, and optically detecting the position of the through hole. Electrically 'observation version' A! A through-hole inspection device for a printed circuit board, comprising a determination system means. (2) The mask means has a light shielding part corresponding to each through hole of the printed board, and has a structure in which the through hole is shielded from light by bringing this light shielding part into close contact with the through hole part7. -1 Characteristic Claim 1
"The sluice of printed circuit boards" described in Section 1. (3) The through-hole inspection device for a printed board as set forth in item 1 of the scope of the patent application, wherein the mask means is a structural trap that forms a light-shielding pattern on the through-hole portion of the printed board.