JPH0746048B2 - Pattern shape observation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] When a pattern of an opaque object such as copper is formed on the surface of a substrate made of a light diffusing resin in a printed board, the pattern shape is optically observed. Regarding the device, specifically, it relates to means for locally observing the pattern on the substrate by limiting the observation range for alignment, etc., and applying pattern shape observation directly to alignment etc. with a simple structure change. For the purpose, an illuminating device is provided so as to obliquely irradiate an opaque pattern formed on the surface of a light diffusing substrate, and an observing device is provided with a pattern shape based on the contrast between the light and darkness of the substrate and the pattern due to re-emitted light from the substrate In the pattern shape observing device provided for observing, the light shielding part is limited in the projection mask of the illuminating device so that the dark part is provided only in the limited observing part of the substrate. The observation device is provided with an imaging mask so that only the re-emitted light from the dark part is observed.

[Industrial application field]

The present invention is a pattern shape observing device for optically observing the pattern shape when a pattern such as copper of an opaque object is formed on the surface of a substrate made of a light diffusing resin in a printed board. The present invention relates to a means for locally observing a pattern on a substrate by limiting an observation range for alignment or the like.

Generally, on a printed board, after the pattern is formed, a connection state test for disconnection and short circuit is performed by an electrical continuity test, and in addition to this, potential defects and protrusions of the pattern are also tested by a pattern visual inspection to improve reliability. I am trying. The pattern visual inspection in this case mainly detects the pattern optically and judges the shape visually, and various methods of observing the pattern shape have been proposed.

By the way, the observation data of the pattern shape is used not only for the visual inspection but also for the alignment of the component lead and the pattern when the component is mounted on the board. In this case, a method is conceivable in which necessary data is extracted from all the pattern shape data on the substrate and processed, but the processing becomes complicated, which is not preferable. Therefore, it is desired to limit the position of the substrate to only a specific pattern that requires alignment and to accurately observe the pattern shape.

[Conventional technology]

Therefore, FIG. 4 (a), which has been already proposed by the applicant of the present invention as an optical observation of the above pattern shape,
There is one shown in (b). That is, reference numeral 1 in (a)
Is a printed board, 2 is a light diffusing substrate made of epoxy resin, 3 is an opaque pattern such as copper formed on the substrate 2, and 4 is a light reflecting plate provided under the substrate 2.

In addition, the pattern 3 side of the substrate 2 is provided with an illumination device 10 and an observation device.
20 are provided. The illumination device 10 includes a light source 11, a condenser lens 12,
A projection mask 13 having a circular light-shielding portion 13a as shown in FIG.
And consists projection lens 14, and oblique irradiation on a substrate dark portion B ₁ is provided in the observation part A as in (b), however, the bright portion B ₂ which projected light C ₁ around the dark portion B ₁ is irradiated directly Is provided. The observation device 20 has an imaging lens directly above the observation portion A.
21 is provided to transmit the image of the pattern edge, the CCD camera 22 converts it into an image signal, and the image processing device 23 displays the pattern shape.

As a result, as shown in (b), the diffused light C ₂ is reflected by the light reflection plate 4 by the projected light C ₁ from the bright portion B _2, and the diffused light C ₂ is passed through the inside of the substrate 2, and the re-emitted light C ₂ by this diffused light C ₂ is transmitted. Radiate ₃ in the dark area B ₁ to the same state as back irradiation. And re-emitted light
The contour shape of the pattern 3 is detected by the contrast of light and dark between the substrate 2 and the opaque pattern ₃ by C ₃ .

[Problems to be Solved by the Invention]

By the way, in the above-mentioned conventional example, since the dark portion B ₁ by the mask 13 is set in a wide range corresponding to the observation portion A, the observation portion A ′ is for alignment as shown by the broken line in (b). If it is limited to a small size, the following problems will occur. That is, in the observation part A ′, a pattern close to the bright part B ₂
In 3a, since the re-emitted light C ₃ is large, the pattern shape is clearly detected. However, in the pattern 3b far from the bright portion B ₂ , the internally diffused light C ₂ is scattered as the scattered light C ₄ as shown in (b), the amount of the re-radiated light C ₃ is reduced, and the shape of the pattern 3b can be detected. Noticeably worse.

Here, when the observation part is limited to A'for alignment, the patterns 3a and 3b within the range must be clearly detected. If it is unclear in the visual inspection, the position of the substrate 2 can be shifted to clarify, but this cannot be done in the alignment. Therefore, for alignment, the pattern 3 of the observation part A ′ limited to a fixed position is used.
It is desirable to detect the shapes of a and 3b clearly.

The present invention has been made in view of the above points, and an object of the present invention is to provide a pattern shape observing device which can directly apply pattern shape observation to alignment and the like by changing a simple structure. .

[Means for Solving the Problems]

In order to achieve the above object, the pattern shape observing device of the present invention sets the light shielding part of the projection mask in the illuminating device so as to be restricted corresponding to the limited observing part for alignment, and to set the observing part of the observing part on the substrate. A bright area is provided near the dark area.

Also, in the observation device, in order to eliminate unnecessary light due to enlargement of the bright part and only the re-emitted light can be observed, an imaging mask having a transmissive part similar in shape to the light shielding part of the projection mask just before the CCD camera is installed. It is provided.

[Action]

Based on the above configuration, only the limited observation part for alignment on the substrate is the dark part by irradiation with the projection mask of the illuminating device, and the surrounding part is the bright part, and most of the diffused light inside the substrate becomes re-emitted light. Then, the contrast of the pattern at all positions in the observation part becomes clear. Further, in the observation device, unnecessary scattering light is removed by an imaging mask, and the shape is observed with an image of the pattern only by the re-emitted light.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a printed board, 2 is a light diffusing substrate, 3 is an opaque pattern, and 4 is a light reflecting plate. An illuminating device 10 is provided on the pattern side of the substrate 2, and a light source 11,
The condenser lens 12, the projection mask 13, and the projection lens 14 enable oblique irradiation. The observation device 20 is an imaging lens.
21, CCD camera 22, image processing device 23, CCD camera 22
The imaging mask 24 is set immediately before.

Here, the case of using for alignment in the case of mounting a component on the board 2 in a plane will be described. As shown in FIG. 5 are provided, and the lands 5 are arranged side by side in a multiplicity of squares. Therefore, in order to two-dimensionally observe the shape of the land 5, the observation portion A ′ may be limited to, for example, an L shape in the row of the land 5. Therefore, in the mask 13, as shown in FIG. 3 (b), the light-shielding portion 13a 'is limited to a similar L-shape corresponding to the observation portion A', and the other portion is the transmission portion 13b '. Further, in the mask 24, as shown in FIG. 7C, the transmission part 24a is L-shaped, and the light shielding part 24b is other than that to remove unnecessary scattered light.

With the above structure, when oblique irradiation by the illumination device 10 'by L-shaped observation part A of the lands 5 of the substrate 2' shielding portion 13a only of the mask 13 as shown in FIG. 2 is a dark part B ₁ ', transmission unit 'vicinity around the the bright portion B _2' 13b projected light C ₁ becomes to irradiation. Therefore, the internal diffused light C _{2 that} has entered the inside of the substrate 2 by the projection light C ₁ immediately enters the observation portion A ′ of the dark portion B ₁ ′, and most of it is reflected by the light reflection plate 4 to become re-emitted light C ₃ . It will be. In this way, sufficient re-emitted light C ₃ is uniformly emitted at all positions of the observation portion A ′, so that the contrast of light and dark of the substrate 2 and the pattern 3 or the land 5 becomes clear at all positions.

On the other hand, due to the enlargement of the bright part B ₂ ′, a large amount of the reflected light of the projection light C ₁ is directed to the observation device 20 side, but the mask 24 just before the CCD camera 22
The light-shielding portion 24b prevents the reflected light from being input. Therefore, only the re-emitted light C _{3 from the} substrate 2 is transferred to the mask 24
The transparent portion 24a enters the CCD camera 22, and the pattern or land shape is observed based on the above-mentioned contrast.

It should be noted that the number of lands observed in the dark portion B ₁ ′ is small in the initial stage of alignment, and the number of lands observed increases as the position of the substrate 2 is two-dimensionally moved and alignment progresses. Then, the alignment ends when the dark portion B ₁ ′ and the observation portion A ′ are aligned and the lands 5 arranged in an L shape are observed.

Although one embodiment of the present invention has been described above, the present invention can be used in addition to alignment with a mounting component and can also be used to observe through holes and the like.

The observation portion A ′ may be defined in U-shape, 3 points or 4 points in addition to the L-shape.

〔The invention's effect〕

As described above, according to the present invention, when observing a pattern shape, it is possible to clearly observe all the local pattern shapes at a plurality of locations. Also improves the resolution.

Since the projection and imaging masks may be determined according to the observation portion, the structure is simple.

The addition of the imaging mask avoids unobservability due to excessive light.

The light quantity of the light source may be reduced for limited observation such as alignment.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a pattern shape observation device of the present invention, FIG. 2 is a perspective view showing a traveling state of light, and FIG. 3 (a) is a diagram showing a limited observation part for alignment.
(B) and (c) are diagrams showing the light shielding and transmitting parts of each mask, FIG. 4 (a) is a configuration diagram of a conventional example, (b) is a perspective view showing a traveling state of light, and (c) is a projection. It is a figure which shows a mask. In the figure, 2 is a substrate, 3 is a pattern, 10 is an illuminating device, 13 is a projection mask, 13 'is a light shielding part, 20 is an observing device, 24 is an imaging mask,
A 'observation portion, B _1' is dark area, C ₃ indicates the re-emitted light.

Claims (1)

[Claims] 1. An illuminating device (10) is provided so as to obliquely illuminate an opaque pattern (3) formed on a surface of a light diffusing substrate (2), and an observing device (20) is provided on the substrate (20). In the pattern shape observing device provided so as to observe the pattern shape by the contrast of the brightness (darkness) of the substrate (2) and the pattern ( ₃ ) by the re-emitted light (C ₃ ) of 2), the projection mask (13) of the illuminating device (10) limit setting the substrate light-shielding portion to provide a 'dark portion (B ₁ only) limited observation portion (a)' in (2) (13a ') in the dark portion in the observation apparatus (20) (B ₁ ′) Re-emitted light (C ₃ )
A pattern shape observing device in which an imaging mask (24) is provided to observe only the pattern.