JPH11119033A - Optical wiring board and wiring method of optical wiring board - Google Patents

Abstract

(57) [Problem] To provide a simple, reliable and highly reliable optical wiring board for interconnecting optical elements and a wiring method on the optical wiring board. SOLUTION: This optical wiring board has one or two or more optical fibers mounted on a rigid substrate using a one-stroke technique. It may be covered with a filler or covered with a flexible film. An optical element or an optical element and an electric element are mounted on the substrate. The substrate may be a printed wiring board. A conductive wire may be mounted on the same surface as the substrate on which the optical fiber is mounted. An optical fiber alignment member may be provided on the substrate, and the end face of the optical fiber may be provided in this member. An optical fiber to which an optical connector is connected in advance may be wired on a board, and the optical connector may be installed on the board. The optical connector may be arranged so that it can be connected to the substrate surface at a certain elevation angle from the horizontal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wiring board and a wiring method for optically connecting optical elements or optical circuits to each other.

In order to connect a plurality of optical elements on an optical board to each other in an optical board of this type equipped with an optical element,
Conventionally, a pigtail optical fiber emerging from one element has been fusion spliced with an optical fiber connected to the other element. When such a fusion splicing is performed, a considerably long extra length is required to set the optical fiber in the fusion splicer outside the board, and this extra length must be accommodated in the board after the connection. Alternatively, a method of connecting optical elements with an optical fiber with a connector using a pigtail with a connector is also used. Also in this case, the optical fiber needs an extra length, and a bundle of optical fibers appears.

On the other hand, in optical wiring between optical boards, an optical fiber is optically connected from the board to another optical board via a connector. Also in this case, since the optical fibers are wired with a certain extra length, a bundle of optical fibers that connects the optical boards is formed on the back of the rack that houses the optical boards. Further, in these conventional methods, both optical fibers to be connected are connected one by one while individually checking them.

A wavelength division multiplexing transmission system which requires complicated optical wiring such as transmitting a plurality of wavelengths to one optical fiber, separating each wavelength in an optical board, performing signal processing, and multiplexing again. In such cases, the number of optical fibers is large, and it becomes very difficult to identify optical fibers to be interconnected. Furthermore, when a failure such as breakage occurs in the optical fiber,
It is very difficult to remove and replace a failed optical fiber.

[0005] As described above, when elements on a board are connected to each other, the conventional method of connecting optical fibers one by one has a serious problem from the viewpoints of work time, work efficiency, maintainability, and the like. , A new connection method was desired.

On the other hand, in an optical wiring board proposed in Japanese Patent No. 2574611 in order to solve these problems, an optical fiber is wired on a flexible substrate. Making the board flexible has the advantage that it can also accommodate vertical connectors between boards by twisting it 90 ° as shown in the patent. However, flexibility is not required for mounting in an optical board, and the output may fluctuate due to vibration of the wiring board due to vibration or the like.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple, reliable and highly reliable optical wiring board for interconnecting optical elements in view of the above-mentioned problems of the prior art. is there. Still another object of the present invention is to provide a wiring method that allows easy handling of a substrate during mounting and facilitates fixing on a board.

[0008]

In order to achieve the above object, the optical wiring board of the present invention has one or two or more optical fibers mounted on a rigid substrate using a one-stroke technique. It is characterized by being made. The one-stroke technique refers to a method of fixing an optical fiber along a wiring path preset on a substrate.

According to the present invention, an optical fiber is fixed on a rigid substrate in accordance with a predetermined pattern, and light is reliably guided from one end of the optical fiber to the other end. Therefore, the connection function of the optical wiring board can be easily obtained, and furthermore, a highly reliable optical wiring board without output fluctuation due to vibration can be obtained, and the wiring board of the present invention is similar to the electric wiring board. It can be easily mounted on a motherboard.

The substrate used for the optical wiring board of the present invention includes:
Plastic plate of thickness 500μm or more, thickness 200μm
More than metal plate, more than 50μm thick glass, 50μm thick
m or more, a composite of plastic or metal or glass or carbon fiber having a thickness of 50 μm or more, or the like can be used.

As a plastic, the softening temperature is 100 ° C.
Any of the above can be used, and for example, polymethyl methacrylate, polystyrene, polyethylene terephthalate, polyimide and the like can be used. As the metal, a lightweight and high-strength metal can be used, and for example, aluminum, stainless steel, titanium and the like are optimal. Glasses having a small coefficient of thermal expansion, fiber-reinforced composite materials, and the like are also suitable materials. In addition, silicon has the V
There is an advantage that grooving can be performed with high accuracy.

The wiring to the rigid substrate can be performed by holding the optical fiber on an adhesive layer or an adhesive layer applied on the rigid substrate or film. The rigid substrate surface is not limited to a flat surface, but may be a curved surface. By processing a rigid substrate into a curved surface in advance and attaching an optically wired film to the substrate, wiring can be easily performed on the rigid substrate. In particular, when connecting between boards, a board bent at 180 °, which is strong against vibration, is necessary, but this can be easily realized by using the above-described method.

Since the optical fiber wired on the substrate via the adhesive layer or the adhesive layer has low mechanical stability as it is, it is desirable to further reinforce the upper part. Also, in the portion where the optical fibers wired on the substrate intersect, the optical fiber in the upper layer is not in contact with the adhesive layer or the adhesive layer and does not provide the optical fiber with adhesiveness or adhesiveness. Floating in space. Therefore, it is desirable that the optical wiring board of the present invention is formed such that the optical fibers on the substrate are covered with the filler.

As the filler, a curable polymer or a thermoplastic polymer is applied on the wiring pattern, and the filling layer is formed by filling the inside of the pattern and covering the entire pattern. This protects against external stress,
The stability of the pattern is improved, and the fluctuation of the optical characteristics is suppressed. For the purpose, the filler polymer used here is ideally one having a high fluidity at the time of filling, no fluidity after filling, and no stress applied to the optical fiber due to curing. Specific examples include silicone polymers and acrylamide gels.

[0015] In the optical wiring board of the present invention, the optical fiber may be covered with a flexible film. A flexible film may be coated on a wiring board wired on a rigid substrate or on the filling layer. By doing so, it is possible to protect against stress from the outside and humidity in the outside world, thereby increasing the stability of the wiring and improving the reliability. Here, as the flexible film, a polymer film or a metal film or a composite of a polymer and a metal, which is thermally stable and has low moisture permeability, such as a polyethylene terephthalate film, a polyimide film, an aluminum foil, and an aluminum-deposited polyethylene A terephthalate film or the like can be used.

In the optical wiring board of the present invention, an optical element or an optical element and an electric element can be mounted on a substrate. Optical wiring has the role of connecting optical elements such as optical switches, optical multiplexers, optical demultiplexers, and wavelength separators, and light sources such as lasers and light-emitting diodes, and light receivers. Therefore, electric elements for driving and controlling the optical elements are mixed. Further, in consideration of connection with another board and mounting on a frame, it is desirable that the optical wiring board itself can mount an optical element and an electric element and has a connector, similarly to a conventional electric board. In this case, a printed wiring board can be used as the substrate of the optical wiring board of the present invention.

The optical elements mounted on the optical wiring board include not only passive elements but also active elements driven by electric power, such as a TO switch and a photodiode. When these are electrically wired, it is desirable not to connect them directly from another board but to connect them from above the optical wiring board via a connector of the board. Therefore, it is desirable to mount a conductive wire on the surface on which the optical fiber is mounted on the substrate of the optical wiring board of the present invention.

Usually, the end face of the wired optical fiber is installed so as to protrude from the substrate in order to attach a connector after the wiring or to perform fusion splicing, but in the optical wiring board of the present invention, A member for aligning the optical fibers may be provided, and the end face of the optical fiber may be provided in this member. For example, by applying a technique of directly attaching a connector to a quartz-based waveguide (see Japanese Patent Application Laid-Open No. 9-159860) to an optical wiring board according to the present invention, an end face of an optical fiber does not protrude from a wiring board, and simple optical connection is achieved. Can be obtained.

Further, in the optical wiring board of the present invention, an optical fiber to which an optical connector is connected in advance may be wired on a substrate, and the optical connector may be provided on the substrate. By wiring with the connector connected and mounting the connector on the wiring board, the extra length of the optical fiber at the time of connection can be greatly reduced. Although the position of the connector on the wiring board may be anywhere, if the plug of the connected connector is located on the end face of the wiring board, there is an advantage that the connector connection in the horizontal direction becomes easy.

In this case, the optical connector may be arranged so that it can be connected to the substrate surface at a certain elevation angle from the horizontal direction. When an optical connector is present inside a wiring board and the connector is connected in a horizontal direction parallel to the surface of the wiring board, the connection work becomes difficult if the connector is small. In order to solve this problem, the connection direction of the connector is shifted from the horizontal plane to the vertical direction with respect to the wiring board surface. Specifically, a method of installing the entire connector obliquely with respect to the wiring board surface, a method of bending a part of the connector to use a connector having a curvature, and the like can be adopted.

The wiring method for an optical wiring board according to the present invention comprises the following steps.
In a wiring method of an optical wiring board in which each of two or more optical fibers is mounted on a substrate using a one-stroke technique, an optical fiber to which an optical connector is connected in advance to at least one end is wired. I do.

In the conventional optical wiring board, a connector is connected after wiring, or connection with an optical element is performed by processing such as fusion splicing. However, in order to perform these steps after the wiring, it is necessary to increase the extra length of the optical fiber, and when the yield is further low, it is necessary to redo the wiring or to perform a new wiring. In order to solve these problems, in the method for wiring an optical wiring board according to the present invention, wiring is performed after connecting an optical connector to at least one end of the optical fiber before wiring.

Here, the connected connector may be the entire connector or a part of the connector, for example, only the plug,
Or it may be a plug and a housing. Also, it is desirable that the connector has the smallest possible volume,
For example, an FPC connector (see JP-A-8-248254) is optimal.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] In FIG. 1, each optical fiber 10 is placed on a substrate 11 by a one-stroke method, and a connector 12 is attached to an end thereof. The substrate is made of polymethyl methacrylate and has a thickness of 500 μm, which is advantageous in that it is a rigid substrate that is strong against vibration and easy to mount.
Each optical fiber is placed on the substrate from one end to the other in a one-stroke technique. The fixing to the substrate uses an adhesive, and is superior in that no stress is applied to the optical fiber due to the curing as compared with the fixing by curing using an adhesive. An FPC connector (Japanese Unexamined Patent Publication No.
No. 48254).

[Embodiment 2] In FIG.
10 are placed on the polymer film 21 by a one-stroke method, and the polymer film 21 is further bent on a curved metal substrate.
Fixed to 20. The metal substrate is obtained by processing an aluminum plate having a thickness of 300 μm into a curved surface, and a polyethylene terephthalate having a thickness of 50 μm on which an optical fiber is mounted is fixed to the upper surface with an adhesive. Therefore, a wiring board having a curved surface and high rigidity can be realized. In this case, it is also possible to bond a pre-wired pattern to a rigid substrate, and the rigid substrate is not necessarily required to be flat, but may be curved. Also,
It goes without saying that an optical fiber can be directly wired on a substrate having a curved surface.

[Embodiment 3] In FIG.
10 is set on the substrate 11 and the lowermost optical fiber is an adhesive layer
It is wired on the substrate 11 via 31. A filling layer 30 is provided above the optical fibers and between the optical fibers. The filling layer 30 is a curable silicone. After wiring the optical fiber, the silicone is applied from above and then cured by heat or light. It is sufficient that the thickness of the filling layer 30 completely covers the optical fiber, and it is sufficient that the thickness is equal to or greater than the thickness of the overlapping portion of the optical fiber. Actually, it is about 250 μm to 1 mm.

The role of the filling layer is not only to protect the upper part of the optical fiber, but also to have an important purpose of stabilizing the pattern shape of the optical fiber at the intersection and preventing contact bending between the optical fibers. That is, since the upper optical fiber does not adhere to the substrate and does not adhere to other optical fibers at the intersection, the mechanical stability is low as it is, and it is desirable to reinforce it. Further, when the wiring pattern is covered with a flexible film, the bending of the optical fiber due to the contact between the optical fibers at the intersection may lead to transmission loss.
To avoid these, a polymer is filled between the optical fibers to reduce the degree of freedom between the optical fibers and to reduce the contact between the optical fibers. In addition, when covered with a flexible film, if there is no filling layer, an air layer is formed between the optical fibers and between the optical fiber and the substrate, and the air layer repeats expansion and contraction due to temperature and the like, There is a possibility that pressure is applied to the optical fiber and the like, and prevention of this is also a major role of the filling layer.

[Embodiment 4] In FIG. 4 (a), each optical fiber 10 is installed on a substrate 11, and the lowermost optical fiber is wired to the substrate 11 via an adhesive layer 31. A filling layer 30 is provided above the optical fibers and between the optical fibers. The upper part of the filling layer 30 is further covered with a flexible protective film 40. Flexible protective film 40 is 50 μm thick
A thermosetting adhesive was applied to the surface of the polyimide film, and the protective film was adhered by heating after installation on the filling layer. Incidentally, regarding the adhesion of the protective film, it is also possible to form the protective layer after applying the filling layer and before curing, and to cure and adhere by heating. In this case, it is not necessary to particularly provide an adhesive layer on the protective layer. . Flexible protective film
40 can also be provided directly on the wiring pattern,
This is effective when the number of intersections of the wiring patterns is small as shown in FIG.

[Embodiment 5] FIG. 5 shows a case where a printed wiring board 50 is used as a substrate and optical fibers 10
FIG. 3 is a diagram showing an optical wiring board mounted together with the optical wiring board. The optical fiber group 10 in the wiring section is connected via a connector 51 to a thermo-optic effect light switch 54 using a heater. The wiring section optical fiber group 10 is wired directly to the printed wiring board,
Optical element 55 with optical multiplexing function located at the rear while crossing
It is connected to the. The input / output optical fibers 58, 59 are installed directly on the printed wiring board 50, and are connected to the optical elements 54, 55 and the external connectors 52, 53, respectively. Electrical element
56 is connected to the printed wiring on the back surface of the printed wiring board, and connection to the outside is made by a connector 57.

[Embodiment 6] FIG. 6 shows an optical fiber of the substrate 11.
An example in which a conductive wire 60 is mounted on the same surface as the surface on which 10 is mounted and connected to a photodetector 61 is shown. The conductive wire 60 is a coated copper wire, and is wired simultaneously with the optical wiring. The optical elements mounted on such a board include not only passive elements but also active elements driven by electric power, such as a TO switch and a photodiode. It is desirable that these be electrically connected from the optical wiring board via a connector of the board without being directly connected from another board for electrical wiring. For this reason, in the present invention, the conductive wire is mounted on the same surface as the substrate on which the optical fiber is mounted.

[Embodiment 7] FIG. 7A is a diagram showing a side surface of an end portion of the optical wiring board, and FIG. 7B is a diagram showing a cross section of the end portion of the optical wiring board. The optical fibers are aligned at equal intervals and equal heights using an optical fiber alignment member formed by the holding plate 70 and the V-groove 71. The end face of the optical fiber 10 is in the V-groove. 250μ to align the optical fiber
A silicon substrate 72 provided with V grooves at an m pitch is embedded in the wiring substrate 11, and the optical fiber 10 is pressed by a pressing plate 70 from above. Although not shown, the PCL connector technology developed for the silica-based waveguide is applied to this optical wiring board, and the end face of the optical fiber to be connected is inserted into the V-groove, and is brought into contact with the optical fiber on the optical wiring board side. Connected.

Embodiment 8 FIG. 8 shows a wiring board in which a connector or a connector plug is attached to the end face of an optical fiber and wired.
It is an example of optical wiring which realizes cross-connection of 64 optical fibers. 8-core ribbon optical fiber on wiring board 11
Eight sets of 10 are wired, and each set is connected to an eight-core optical connector plug 80. The ribbon-shaped optical fibers are arranged one by one at a straight portion in the middle, and intersect at a terminal portion 81 into 32 cores. Here, the optical connector needs to be small and highly operable, and a plug of the FPC connector is used. The optical fibers need not necessarily be wired in an eight-core ribbon shape, and may be separated one by one. Further, in the example of FIG. 8, the end face of the connector is flush with the end face of the wiring board, but may be placed anywhere on the wiring board. Further, both ends of the optical fiber may be provided with connectors.

Embodiment 9 FIG. 9 is an enlarged view of a connector portion. An optical fiber 10 is wired on a substrate 11, and a connector plug 90 is provided at an end thereof at an elevation angle of 15 ° with respect to the substrate surface. The part 91 below the connector provides an elevation angle and is made of plastic. When an elevation angle is given to the connector plug, there is an advantage that the workability of attaching and detaching the connector is significantly improved. The elevation angle is optimally in the range of 10 ° to 90 °. In the example of FIG. 9, a method of inserting components into the lower portion of the connector to give an elevation angle has been described, but the connector itself may be structured to give an elevation angle in advance.

[0034]

As described above, according to the present invention,
It is possible to realize an optical wiring board for connecting optical elements to each other simply, reliably and reliably.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of an optical wiring board of a flat substrate.

FIG. 2 is a perspective view of an example of an optical wiring board having a curved surface.

FIG. 3 is a cross-sectional view of an example of an optical wiring board covered with a filler.

FIG. 4 is a cross-sectional view of an example of an optical wiring board covered with a flexible film.

FIG. 5 is a plan view of an example in which a printed board is used as a board of a wiring board.

FIG. 6 is a plan view of an example in which electric wiring is mixed in an optical wiring board.

FIG. 7 is a cross-sectional view of an example in which an optical fiber alignment member is provided on a substrate.

FIG. 8 is a plan view of an example in which a connector is attached to an end of an optical fiber and wiring is performed.

FIG. 9 is a side view of an example in which a connector is installed on a wiring board at a fixed elevation angle.

[Explanation of symbols]

 Reference Signs List 10 optical fiber 11 substrate 12 connector 20 metal substrate 21 polymer film 30 filling layer 31 adhesive layer 40 flexible protective film 50 printed wiring board 51, 52, 53 optical connector 54, 55 optical element 56 electrical element 57 electrical connector 58, 59 Input / output optical fiber 60 Conductive wire 61 Photodetector 70 Holding plate 71 V-groove 72 Silicon substrate 80 Optical connector plug 81 Optical fiber termination 90 Connector plug 91 Elevation angle imparting part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shuichiro Asakawa Nippon Telegraph and Telephone Corporation 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo

Claims (10)

[Claims] 1. An optical wiring board comprising one or two or more optical fibers mounted on a rigid substrate using a one-stroke technique. 2. The optical wiring board according to claim 1, wherein the optical fiber is covered with a filler. 3. The optical wiring board according to claim 1, wherein the optical fiber is covered with a flexible film. 4. The optical wiring board according to claim 1, wherein an optical element or an optical element and an electric element are mounted on the substrate. 5. The optical wiring board according to claim 1, wherein the substrate is a printed wiring board. 6. The optical wiring board according to claim 4, wherein a conductive wire is mounted on the same surface as a substrate on which the optical fiber is mounted. 7. The optical wiring board according to claim 1, wherein an optical fiber alignment member is installed on the substrate, and an end face of the optical fiber is installed in the member. . 8. An optical fiber according to claim 1, wherein an optical fiber to which an optical connector is connected in advance is wired on the substrate, and the optical connector is set on the substrate. Optical wiring board. 9. The optical wiring board according to claim 8, wherein the optical connector is arranged so as to be connectable to the substrate surface from a horizontal direction at a certain elevation angle. 10. A wiring method for an optical wiring board in which one or two or more optical fibers are mounted on a substrate using a one-stroke technique, wherein an optical fiber having an optical connector connected to at least one end in advance is used. A wiring method for an optical wiring board, comprising wiring.