JPH06317537A - Board inspection equipment - Google Patents

Abstract

PURPOSE:To improve the reliability, attain miniaturization and reduce cost in a board inspection equipment in which the board is inspected by using a fiber including a fluorescent dye. CONSTITUTION:A laser light 34a is radiated to a via-hole 12, which is filled with a conductor 13 of a green sheet 11, in a vertical direction by a light irradiation system 32, the reflecting lights are inputted to the side surfaces of fluorescence fiber fluxes 37 which are arranged in an oblique direction on the both sides of the via-hole 12, and they are outputted from output faces to a first optical detector 38. Then, the output from the first detector 38 is compared with a reference voltage Vr by a comparator 39 so as to judge the filling condition of the conductor 13 in the via-hole 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate inspection device for inspecting a substrate using a fiber containing a fluorescent dye.

In recent years, with the increase in the density of wiring patterns and the increase in signal processing speed, the material of the printed circuit board is shifting from plastic to ceramics having high thermal conductivity and insulation, and It is becoming a multi-layer substrate. The multilayer ceramic substrate is formed by stacking green sheets each having a plurality of via holes filled with respective wiring patterns and conductors, and sintering the green sheets.

There are tens of thousands of via holes formed on one surface, and it is required to automatically check the filling amount of the conductors visually. In automation, there is a demand for a highly reliable, compact, and low-cost product.

[0004]

2. Description of the Related Art Conventionally, a through hole in a plastic-based multi-layer substrate is copper-plated in order to form a through hole (via hole) and to electrically connect the inside.
In the case of a ceramic-based multilayer substrate, as described above, the via holes of the green sheet are filled with a conductor. An optical method is used to automatically inspect the filled state of the conductor.

Here, FIG. 5 shows a diagram for explaining an inspection object. 5A to 5D show a case where a predetermined number of via holes 12 are formed in a green sheet 11 before firing in a ceramic-based multilayer substrate, and the via holes 12 are filled with a paste-like conductor 13. Shows the state of.

FIG. 5A shows the case where the entire via hole 12 is filled with the conductor 13, and shows a normal state. 5 (B) shows a state in which the via hole 12 is not filled with the conductor 13 at all, and FIG. 5 (C) shows a state in which the conductor 13 is insufficiently filled and there is a space above.
FIG. 5D shows a state in which the upper surface of the conductor 13 in FIG. In FIG. 5D, even if a part of the conductor 13 reaches the upper part of the via hole 12, the continuity of the wiring pattern between the green sheets 11 cannot be obtained when there is a space.

Therefore, FIG. 6 shows a block diagram of a conventional substrate inspection apparatus. The substrate inspection apparatus 21 of FIG. 6 is roughly composed of a light irradiation system 22 and an oblique observation system 23, as described in Japanese Patent Application Laid-Open No. 1-297189 (Japanese Patent Application No. 63-124944).

The light irradiation system 22 scans the laser light 24a emitted from the laser light source 24 with the rotating mirror 25, and irradiates the via hole 12 of the green sheet 11 from the vertical direction via the condenser lens 26.

The oblique observation system 23 includes a condenser lens 27 in which the reflected light from the green sheet 11 is obliquely arranged.
The light is detected by the photodetector 28 via. The output from the photodetector 28 is compared with the reference voltage (threshold voltage) by the comparison circuit 29, and the output of the comparison circuit 29 indicates the filling state of the conductor 13.

That is, when the conductor 13 is in the state shown in FIG. 5A, the laser beam 24a irradiated on the green sheet 11 from the vertical direction is reflected on the upper surface of the conductor 13 and the photodetector 28 of the oblique observation system 23 is detected. The reflected light is detected. Further, in the state of FIG. 5B, the laser light 24a is not reflected on the upper surface of the conductor 13 and the photodetector 28 does not detect the reflected light.

Further, in the states of FIGS. 5 (C) and 5 (D),
Even if the laser light 24a is reflected on the upper surface of the conductor 13, the photodetector 28 does not detect the reflected light because of the space. Figure 5
In (B) to (D), the output of the photodetector 28 is the reference voltage Vr.
Since it is smaller, it is observed from the output of the comparison circuit 29 as a defective state.

[0012]

However, as described above, detecting the reflected light from the conductor 13 by the oblique observation system 23 is because the scanning distance of the laser light 24a to be irradiated is long, and therefore the light irradiation position There is a problem in that the distance from the (reflection position) to the photodetector 28 becomes long, so that the condenser lens 27 becomes large and the entire apparatus becomes large.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a substrate inspecting apparatus for improving reliability, downsizing, and cost reduction.

[0014]

The above-mentioned problems are solved by irradiating a hole formed in a predetermined number of individual sheet substrates constituting a multi-layer substrate and filled with a conductor with light to reflect the reflected light from the conductor. In a substrate inspection device for inspecting a filling state, a predetermined number of waveguide means containing a fluorescent dye for inputting and outputting the reflected light between an input surface and an output surface continuous with the input surface, and the waveguide means. A first light detecting means for detecting the light output from the output surface of the device, and a determining means for determining the filling state of the conductor in the hole based on the output from the first light detecting means. It is solved by doing.

[0015]

As described above, when light is applied to the holes filled with the conductor of the sheet substrate, the reflected light is guided to the first light detecting means by the waveguide means, and the reflected light is guided to the first light detecting means. From the output, the judging means judges the filling state of the conductor in the hole.

In this case, the wave guide means contains a fluorescent dye, and allows reflected light to be input to the input surface (for example, the side surface in the axial direction of the fiber) and the output surface continuous to the input surface (for example, the side surface of the fiber). And output to the output surface.

As a result, the waveguide means can be arranged close to the hole to be inspected, and the reliability of inspection can be improved. Further, since the condenser lens is not used, the size can be reduced, and the cost can be reduced accordingly.

[0018]

FIG. 1 is a block diagram of the first embodiment of the present invention. The inspection target is given the same reference numeral as in FIG.

As described above, the object to be inspected by the substrate inspecting apparatus 31 of FIG. 1 (A) is the green sheet 11 which is a sheet substrate, in which a plurality of via holes 12 are formed, and a paste form is formed in the via holes. Is filled with the conductor 13. A plurality of these green sheets are stacked and fired to form a multilayer substrate.
At this time, the via hole 12 (conductor 13) plays a role of electrically connecting the green sheets.

Therefore, the board inspection apparatus 3 shown in FIG.
1 is roughly divided into a light irradiation system 32 and an oblique observation system 33.

The light irradiation system 32 is composed of a laser light source 34, a rotating mirror 35 and a condenser lens 36. That is, the laser light 34a emitted from the laser light source 34 is scanned by the rotating mirror 35, is condensed by the condenser lens 36, and irradiates the via hole 12 of the inspection target portion from the vertical direction.

Further, the oblique observation system 33 includes a fluorescent fiber bundle 37 composed of a plurality of fluorescent fibers 37a which are wave guiding means, a photodetector 38 which is a first photodetecting means, and a comparing circuit which is a judging means. It is composed of 39.

In the fluorescent fiber bundle 37, as shown in FIG. 1B, the same number of fluorescent fiber bundles 37 ₁ and 37 ₂ are arranged symmetrically on both sides of the via hole 12 of the green sheet 11. For example, as shown in FIG.
The irradiation part 4a is arranged in an arcuate shape within an allowable range so that the reflected light can be input in a wide range with the irradiation part being in an open state.

The fluorescent fiber 37a has a side surface as an input surface and one end surface continuous with the side surface as an output surface (or vice versa), and contains, for example, a perylene fluorescent dye. That is, when the light input from the side surface of the fluorescent fiber 37a enters the fluorescent dye contained therein, the fluorescent dye absorbs the incident light and emits light, and the emitted light is output from the end face (output face) as output light. is there.

Further, the photodetector 38 uses the fluorescent fiber bundle 3
7 provided on the output end face of each of the fluorescent fibers 37
The output from a is received, photoelectrically converted, and output. Then, the comparison circuit 39 compares the output from the photodetector 38 with the reference value voltage Vr and outputs it. This output represents the filling state of the conductor 13 filled in the via hole 12.

In such a substrate inspection apparatus 31, first, the laser light source 34 to the rotating mirror 35 are provided in the via hole 12.
And the laser beam 34 from the vertical direction through the condenser lens 36.
Irradiate a. At this time, if the conductor 13 is filled in the via hole 12 by a predetermined amount, the laser beam 34 a is incident on the surface of the conductor 13 and reflected. The reflected light at this time is scattered light, and the fluorescent fiber bundle 3 arranged obliquely
It is incident on the side surfaces of 7 ₁ and 37 ₂ .

The light output from the end surface (output surface) of the fluorescent fiber bundle 37 is photoelectrically converted by the photodetector 38 in accordance with the incident light, and is input from one input terminal of the comparison circuit 39.
In the comparison circuit 39, the output of the photodetector 38 is compared with the reference voltage Vr input from the other input terminal and output.

Here, FIG. 2 shows an explanatory view of a detection state for a via hole. 2 (A) to FIG. 5 (A)
2 (B) corresponds to FIG. 2 (A).
6 is a graph of output signals of the photodetector 38 corresponding to.

As shown in FIG. 2A, the via hole 12
When the conductor 13 is filled up to the upper part of the above, a large amount of light reflected from the surface of the conductor 13 is incident on the fluorescent fiber bundle 37, and as shown in FIG. The output signal from 38 is a threshold value (reference voltage Vr)
The level becomes higher, and a signal is output from the comparison circuit 39 as a normal state.

Further, as shown in FIG. 2A, when the via hole 12 is not filled with the conductor 13 and there is a space above the conductor 13, the fluorescent fiber bundle 37 is connected to the via hole 12. The incident light is reduced, the output of the photodetector 38 becomes low level, and a signal is output from the comparison circuit 39 as a defective state.

As described above, by providing the waveguide means such as the fluorescent fiber bundle 37 in a wide range diagonally on both sides of the light irradiation position, the reliability of the via hole inspection can be improved, and the condenser lens and the like can be improved. Since it is not necessary, the device can be downsized and the cost can be reduced.

Next, FIG. 3 shows a block diagram of a second embodiment of the present invention. In the board inspection apparatus 31 of FIG. 3, first, the green sheet 11 to be inspected is placed on the XY table 41,
A fluorescent fiber bundle 37 is arranged on the green sheet 11 as shown in FIG. In this case, A indicates the scanning direction of the irradiated laser beam 34a, and B indicates the reflected light.

Further, in this embodiment, a vertical observation system is provided. This vertical observation system 42 detects a beam splitter 43a which is a spectroscopic means provided in the middle of the optical path between the laser light source 34 and the rotating mirror 35, and a vertical reflection light from the via hole 12 which is split by the beam splitter 43a. Two
And a second photodetector 43b, which is a photodetection unit of. The configurations of the other light irradiation system 32 and the oblique observation system 33 are the same as those in FIG.

The output of the first photodetector 38 is sent to one input terminal of the first comparison circuit 44, and the reference voltage Vr is input to the other input terminal. On the other hand, the second photodetector 4
The output of 3b is sent to one input terminal of the second comparison circuit 45, and the reference voltage Vr is input to the other input terminal. Then, the output of the first comparison circuit 44 is sent to one input end of the AND circuit 46, and the output of the second comparison circuit 45 is sent to the other input end. In addition, the second comparison circuit 45
Is sent to the output terminal 47a, and the output of the AND circuit 46 is sent to the output terminal 47b. The first and second comparison circuits 44 and 45 and the AND circuit 46 constitute a judgment means.

The substrate inspection apparatus 31 as described above irradiates the XY table 41 while scanning the laser beam 34a for each predetermined region of the green sheet 11 in the A direction from the vertical direction. In addition, in the present embodiment, of the reflected light from the via holes 12 of the green sheet 11, the vertically reflected light is
Condensing lens 36, rotating mirror 35, beam splitter 4
It is detected by the second photodetector 43 via 3a.

That is, when the conductor 13 is filled up to the upper part of the via hole 12 (not shown) of the green sheet 11 (FIG. 2A), the first and second comparison circuits 44 and 45 are Both outputs become high level, and the output of the AND circuit 46 becomes high level. However, when the conductor 13 is filled and there is a space above the conductor, the output of the second comparison circuit 43 becomes high level. And the first comparison circuit 38
Output goes low. If the conductor 13 is not filled at all (FIG. 2 (A)), the outputs of the first and second comparison circuits 44 and 45 and the AND circuit 46 are all at a low level, and the contents of the defect can be easily identified. Can be distinguished.

As described above, by providing the fluorescent fiber bundles 37 for detecting the reflected light of the green sheet 11 on both sides of the light irradiation position, the inspection device itself can be made compact, the cost can be reduced, and the left and right sides can be provided in the upper part of the via hole. The via hole 12 having a space above the conductor 13 regardless of the presence of an asymmetric space can be reliably detected, and the reliability can be improved.

Next, FIG. 4 shows a block diagram of a third embodiment of the present invention.

The board inspection apparatus 31 shown in FIG.
The fluorescent fiber bundle 37 shown in FIG.
The fluorescent fiber bundles 3 on both sides of the
7₁, 37₂On each end face (output face) of
1A and 1B photodetectors 38₁, 38₂And this
1A and 1B comparison circuits 4
Four ₁, 44₂To send. And 1A and 1B
Comparing circuit 44₁, 44₂Each output is an AND circuit
46a and its output is one of the outputs of the AND circuit 46.
It is sent to the input end. Other configurations are the same as in FIG.
is there.

By the way, as shown in FIG. 4 (B) (FIG. 2 (A)), in the case where there is a left-right asymmetric space above the conductor 13 in the via hole 12, as shown in FIG. When the light detector 38 of No. 1 detects the light, the reflected light from the asymmetrical upper surface of the conductor 13 may be received to judge the normal state.

Therefore, in the present embodiment, the incidence on the left and right fluorescent fibers 37 ₁ and 37 ₂ is detected separately by the first and second photodetectors 38 ₁ and 38 ₂ , respectively.
It is possible to prevent erroneous judgment.

That is, when the conductor 13 is filled up to the upper part of the via hole 12 (FIG. 2A), the first
A, the output of the 1B and second comparator circuits 44 _1, 44 _2, 45 output goes both to the high-level AND circuit 46,46a is goes high, the conductor 13 is filled, and the conductor 13 If there is a space above (Figure 2 (A)),
The output of the second comparison circuit 45 becomes high level, and the first A and first B comparison circuits 44 ₁ and 44 ₂ and the AND circuit 4 are provided.
The output of 6,46a goes low.

If the conductor 13 is not filled at all (FIG. 2A), the first and second comparison circuits 44 ₁ ,
The output of the 44 _2, 45 and the AND circuit 46,46a can easily distinguish the defect content is all low.

Further, when there is a left-right asymmetric space in the upper part of the via hole 12 (FIG. 2 (A)), depending on the shape of the space, the first A and the first B photodetectors 38 ₁ , 38 ₂ are detected.
The output is different, and one of them becomes high level and one becomes low level, and the output becomes low level by the AND circuit 46a, and it is judged that there is a defect.

As described above, the fluorescent fiber bundles 37 are provided on both sides of the light irradiation position so as to detect the reflected light of the green sheet 11, and the first A and the first B photodetectors 3 are respectively provided.
By detecting light with 8 ₁ and 38 ₂ , the device itself can be downsized, the cost can be reduced, and reliable detection can be performed regardless of the case where there is a left-right asymmetric space in the upper part of the via hole 12, and reliability is improved. It can be done.

[0046]

As described above, according to the present invention, the holes filled with the conductor of the sheet substrate are irradiated with light, and the reflected light is input / output between the input surface and the output surface continuous with the input surface. The reliability of the inspection is improved and the size of the apparatus is reduced by guiding the light to the first photo-detecting means by the wave-guiding means containing the fluorescent dye and determining the filling state of the conductor from the output of the first photo-detecting means. And cost reduction can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a detection state for a via hole.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a third conventional example.

FIG. 5 is a diagram for explaining an inspection target.

FIG. 6 is a configuration diagram of a conventional board inspection device.

[Explanation of symbols]

 11 Green Sheet 12 Via Hole 13 Conductor 31 Substrate Inspection Device 32 Light Irradiation System 33 Oblique Observation System 34 Laser Light Source 34a Laser Light 35 Rotating Mirror 36 Condensing Lens 37 Fluorescent Fiber Bundle 37a Fluorescent Fiber 38 Optical Detector (First Light) Detector) 39 Comparison circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikazu Kaki 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (5)

[Claims] 1. A light (34a) is irradiated to a hole (12) formed in a predetermined number on each sheet substrate (11) constituting a multi-layer substrate and filled with a conductor (13), and the reflected light from the reflected light is used. A substrate inspection device for inspecting the filling state of the conductor (13), wherein a predetermined number of waveguides containing a fluorescent dye that input and output the reflected light between an input surface and an output surface continuous with the input surface. Means (37) and first light detecting means (38, 38 ₁ , 38 ₂ ) for detecting the reflected light output from the output surface of the waveguide means (37)
And a judging means (39, 44, 45) for judging the filling state of the conductor (13) in the hole (12) from the output from the _first light detecting means (38, 38 ₁ , 38 ₂ ). ), And a substrate inspection apparatus comprising: 2. The first and second waveguide means (37 ₁ , 37 ₂ ) are symmetrically arranged on both sides of the hole irradiated with light as the waveguide means (37). The board inspection apparatus according to claim 1. 3. A single photodetector (38) for detecting the first photodetecting means with any output light from the first and second waveguide means (37 ₁ , 37 ₂ ). 3. The board inspection apparatus according to claim 2, wherein 4. The first light detection means is provided with the first and
Second waveguide means (37₁, 37₂) Output light from it
First and second photodetectors (38 for detecting each) ₁, 3
8₂3. The substrate according to claim 2, wherein
Inspection device. 5. Light (34) from the direction perpendicular to the hole (12).
a) is provided and a spectroscopic means (43a) for extracting the reflected light in the vertical direction and a second light detection means (43b) for detecting the reflected light from the spectroscopic means (43a) are provided. Means for detecting the first light detecting means (38, 3)
8 ₁ , 38 ₂ ) or the first and second light detecting means (3
8, 38 ₁ , 38 ₂ , 43 b) based on the output from
The board inspection apparatus according to claim 4, wherein the filling state of the conductor (13) in the hole (12) is determined.