JP2001318251A - Optical wiring layer, optical/electrical wiring board and mounting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical wiring layer, an optical/electrical wiring board and a mounting board which are large in size and satisfactory in performance. SOLUTION: Plural small optical wiring layers which are composed of at least cores and claddings are adjacently arranged on the same plane, so that the respective cores are match.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wiring layer in which an optical wiring for transmitting an optical signal is formed, an optical / electric wiring board in which the optical wiring layer is combined with an electric board, and an optical / electric wiring board. The present invention relates to a mounting board on which an optical component or an electrical component is mounted.

[0002]

2. Description of the Related Art In order to produce a computer capable of performing arithmetic processing faster, the clock frequency of a CPU tends to increase more and more, and the clock frequency of the order of 1 GHz is now appearing. As a result, there is a portion where a high-frequency current flows in the electric wiring made of copper on the printed circuit board in the computer, so that malfunction occurs due to generation of noise, and electromagnetic waves are generated and adversely affect the surroundings. It will also be.

In order to solve such a problem, a part of the copper-based electric wiring on the printed circuit board is replaced with an optical wiring, and an optical signal is used instead of an electric signal. This is because, in the case of an optical signal, generation of noise and electromagnetic waves can be suppressed.

[0004] Initially, optical fibers were used as optical wiring. Since the technology of the optical fiber has been almost established as an optical communication system, it has been relatively easy to convert the optical fiber. However, when the number of wirings increases, connection with an optical fiber is not easy, and wiring in an optical wiring layer in which an optical waveguide is formed in a layer has been studied. Quartz was initially used as the optical wiring layer, but it was easy to manufacture.
Since it is easy to cope with an increase in area, a polymer system has been studied.

However, even in the case of a polymer, there is a limit to the size of the waveguide in order to ensure the performance of the waveguide. This is because when a large optical wiring layer is manufactured, dimensional accuracy is deteriorated. Therefore, it has been difficult to produce a large optical / electrical wiring board. Alternatively, it has been difficult to maintain good characteristics with a large optical / electrical wiring board.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical wiring layer, an optical / electrical wiring board, and a mounting board having large and good performance. And

[0007]

In order to achieve the above-mentioned object, first, according to the first aspect of the present invention, a plurality of small optical wiring layers each including at least a core and a clad are aligned with each other on the same plane. And an optical wiring layer characterized by being disposed adjacent to the optical wiring layer.

According to a second aspect of the present invention, there is provided the optical wiring layer according to the first aspect, wherein the core width is increased in the vicinity of the connection portion of the small optical wiring layer.

According to a third aspect of the present invention, there is provided the optical wiring layer according to the first or second aspect, wherein a connection surface of the small optical wiring layer is inclined with respect to the core.

According to a fourth aspect of the present invention, the connecting surface of the small optical wiring layer is corrugated, and the convex and concave portions are connected so as to engage with each other. The optical wiring layer described in the section.

According to a fifth aspect of the present invention, there is provided the optical wiring layer according to the fourth aspect, wherein the convex portion has a portion whose width is larger than the root.

According to a sixth aspect of the present invention, there is provided an optical / electrical wiring board having the optical wiring layer according to any one of the first to fifth aspects.

According to a seventh aspect of the present invention, there is provided an optical device according to the sixth aspect.
This is a mounting board characterized by mounting components on an electric wiring board.

[0014]

Embodiments of the present invention will be described in detail below. The optical wiring layer is a layered structure having an optical wiring therein. The main part of the optical wiring is a linear part called a core. Other parts are called cladding. The core and the clad are made of a material that is transparent to light having a wavelength to be used. The refractive index of the core is set higher than that of the cladding, and light usually propagates along the core.

It is difficult to manufacture a large optical wiring layer with high accuracy and no defect. The present invention has been made by finding that a good optical wiring layer can be obtained by manufacturing a small optical wiring layer with high accuracy and no defect and then bonding them on the same plane. FIG. 1 is an explanatory view showing a perspective view of one embodiment of the optical wiring layer of the present invention. The large optical wiring layer 2 is formed as a whole by arranging the small optical wiring layers 1 on the large substrate 3 so as to be adjacent to each other so that the cores are aligned with each other and bonding them.
If an electric wiring board is used as the substrate 3, it becomes an optical / electric wiring board. When an optical component or an electrical component is mounted by providing a via hole in the optical wiring layer and attaching an electrode pad through the via hole, a mounting substrate is obtained.

Also, when bonding the small optical wiring layers on the same plane, there is a problem of core misalignment due to a positional shift between the small optical wirings. According to the present invention, a favorable optical wiring layer can be easily obtained by reducing the influence of the positional deviation or making the positional deviation hard to occur.

In order to reduce the influence of the displacement, it is effective to increase the core width in the vicinity of the connection portion more than usual. FIG. 2 is an explanatory view showing another embodiment of the optical wiring layer of the present invention in a plan view, and FIG. 6 is an explanatory view showing a comparative example of the present invention in a plan view. When a positional shift occurs at a normal core width as shown in FIG. 6, the transmitted light 7 becomes stray light 8 at the shifted portion and does not propagate. However, for example, as shown in FIG. 2A, when the core 4 in the clad 5 is tapered near the connection surface 6 to increase the core width and propagate the light 7, as shown in FIG. 2B. Even if it is shifted, the light 7 propagates and can transmit a signal. In particular, as shown in FIG. 2 (c) or (d), when the core width on the incident side is larger than the core width on the output side, a good connection with little stray light to the clad can be obtained even if there is some displacement.
These cores can be manufactured, for example, by patterning the photomask into the shape shown in the drawing when patterning the core using a normal photolithography technique.
The same applies to the case where the core is patterned using photolithography and dry etching.

As a method of making the displacement in the thickness direction less likely to occur, a method of making the connection surface oblique to the core is effective. FIG. 3 is an explanatory diagram showing a cross section of another embodiment of the optical wiring layer of the present invention, and FIG. 7 is an explanatory diagram showing a comparative example of the present invention in cross section. This is an example in which an optical wiring layer is bonded on a substrate 3 by an optical adhesive 9. When a normal connection surface perpendicular to the core is used, as shown in FIG. 7, displacement in the thickness direction occurs due to a difference in pressure at the time of bonding, and light 7 propagating in the core is transmitted through the connection surface. It becomes stray light 8. However, if the connection surface is inclined with respect to the core as shown in FIG. 3A, pressure is applied to the optical wiring layers at the time of bonding, and a large displacement does not occur. Even if there is some deviation in the lateral direction, the influence is small as shown in FIG. 3B, and the light 7 propagating in the core can propagate without being affected. Laser processing is suitable for making the connection portion oblique. By irradiating and scanning the laser beam from an oblique direction, it is possible to easily perform the oblique cutting.

In order to make it difficult for positional displacement in the direction along the connection side to occur, it is effective to make the connection surface corrugated and connect the convex portions and the concave portions so as to engage with each other. FIG. 4 is a plan view showing another embodiment of the optical wiring layer of the present invention, and FIG.
FIG. 4 is an explanatory view showing a comparative example with the present invention in a plane. Light 7 propagating through the core 4 in the clad 5 passes through the connection surface 6 and propagates to an adjacent wiring layer. On a normal, linear connection surface, a shift along the connection side easily occurs as shown in FIG. 8, and the transmitted light 7 becomes stray light 8. However, FIG.
If the connection surface is corrugated as in (a) or (b) so that the protrusions and recesses are engaged with each other, a force that cancels the displacement along the connection side at the time of bonding acts to cause a large displacement. Instead, the light 7 that has propagated through the core 4 in the cladding 5 propagates through the connection surface 6 to the adjacent wiring layer. To make the connection surface corrugated, it is preferable to dry-etch after forming a corrugated mask pattern with photolithography. Alternatively, it can be obtained by scanning a laser with a waveform.

In order to make it difficult for the displacement in the direction parallel to the plane of the optical wiring layer and perpendicular to the connection side to occur, when the connection surface is corrugated, the shape having a portion where the width of the projection is larger than the root is used. It is effective to FIG. 5 is an explanatory view showing another example of the optical wiring layer of the present invention in a plan view, and FIG. 9 is an explanatory view showing a comparative example of the present invention in a plan view. With a normal waveform, a shift in a direction perpendicular to the connection side as shown in FIG. 9 cannot be canceled. However, according to FIG. 5, a force that cancels even a displacement perpendicular to the connection side at the time of bonding works, and a large displacement does not occur. The manufacturing method is the same as that for the waveform. What is necessary is just to use a mask in which a pattern having a shape in which the width of the convex portion is larger than the root is used, or scan the laser with such a shape.

Incidentally, a structure combining these inventions is also possible. In addition, at least for bonding between the small optical wiring layers, an optical adhesive having a smaller refractive index than the core is desirable,
Further, an optical adhesive having substantially the same refractive index as that of the clad is desirable. Other adhesives may be used in the portion where the small optical wiring layer is bonded to the substrate. The adhesive may be bonded to the substrate only in the vicinity of the connection surface, or may be bonded to the entire optical wiring layer.

[0022]

Since the present invention has the above-described configuration and operation, it has the following effects.

First, by arranging a plurality of small optical wiring layers on the same plane, a large and highly accurate optical wiring layer, optical / electrical wiring board, and mounting board can be obtained.

Second, a favorable optical wiring layer, an optical / electrical wiring board, and a mounting board can be easily obtained by reducing the influence of the positional deviation and making the positional deviation less likely to occur.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an optical wiring layer of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the optical wiring layer of the present invention in a plan view.

FIG. 3 is an explanatory diagram showing a cross section of another embodiment of the optical wiring layer of the present invention.

FIG. 4 is an explanatory view showing another embodiment of the optical wiring layer of the present invention in a plan view.

FIG. 5 is an explanatory view showing a planar view of another embodiment of the optical wiring layer of the present invention.

FIG. 6 is an explanatory view showing a comparative example of the optical wiring layer of the present invention in a plane.

FIG. 7 is an explanatory view showing a comparative example of the optical wiring layer of the present invention in cross section.

FIG. 8 is an explanatory view showing a plan view of a comparative example of the optical wiring layer of the present invention.

FIG. 9 is an explanatory diagram showing a comparative example of the optical wiring layer of the present invention in a plane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Small optical wiring layer 2 ... Optical wiring layer 3 ... Substrate 4 ... Core 5 ... Clad 6 ... Connection surface 7 ... Light 8 ... Stray light 9 ... Optical adhesive

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Ichikawa, Inventor, 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Kenta Yotsui 1-1-1, Taito, Taito-ku, Tokyo F-term in Toppan Printing Co., Ltd. (Reference) 2H047 KA03 KA13 KA15 KB03 KB09 TA05 TA42 5E338 AA00 AA16 AA20 BB75 BB80 CC01 CD01 EE21 EE32

Claims (7)

[Claims] 1. An optical wiring layer, wherein a plurality of small optical wiring layers each including at least a core and a clad are arranged adjacently on the same plane so that the cores are aligned with each other. 2. The optical wiring layer according to claim 1, wherein the core width is large in the vicinity of the connection portion of the small optical wiring layer. 3. The optical wiring layer according to claim 1, wherein the connection surface of the small optical wiring layer is inclined with respect to the core. 4. A connection surface of a small optical wiring layer has a waveform,
The optical wiring layer according to any one of claims 1 to 3, wherein the convex portion and the concave portion are connected so as to engage with each other. 5. The optical wiring layer according to claim 4, wherein said optical wiring layer has a portion in which the width of the convex portion is larger than the root. 6. An optical / electrical wiring board having the optical wiring layer according to claim 1. 7. A mounting board, wherein components are mounted on the optical / electrical wiring board according to claim 6.