JPS63293509A - Production of optical circuit board - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce an optical circuit board which decreases the propagation loss of light and has high accuracy by filling a resin to serve as a core into grooves formed on the surface of a planar substrate, then sticking a cover constituting a part of a clad to the apertures of the grooves. CONSTITUTION:The curable resin 2 is filled into the grooves 11 formed on the surface of the planar substrate 1 and the cover 3 is put and pressed on the substrate surface to spread the bleeding out resin, by which the cover 3 is stuck to the substrate. The inside wall surfaces of the grooves and the surface of the cover in contact with the grooves are finished to specular surfaces so that the refractive index after curing of the resin is made higher than the refractive index of the cover 3. Light guides 4 formed in such a manner decreases the propagation loss of light. The optical circuit board having high accuracy is thus easily and expensively produced.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a method for manufacturing an optical circuit board.

[Background technology]

Inside optical equipment used for optical measurement and sensing, optical circuits are used to guide light from an external optical system to a light-receiving element, or to guide light emitted from a light-emitting element to an external optical system. A plate (planar optical waveguide) is used.

Conventionally, various methods using inorganic materials and organic materials have been proposed as methods for manufacturing such optical circuit boards. For example, methods ■ and ■ below are examples.

(2) Glass particles with a high refractive index are deposited on a quartz substrate, sintered into glass, and then the sintered glass is etched leaving only the core portion. Furthermore, glass particles with a lower refractive index than the core are deposited on this core and sintered.
A cladding layer is formed to obtain an optical circuit board.

■ Fabricate a high refractive index polymer sheet containing monomers that form a low refractive index polymer when exposed to light. Next, this high refractive index polymer sheet is irradiated with actinic rays except for the core portion thereof, and then unreacted monomers are removed under vacuum. Finally, both sides of the sheet are coated with a low refractive index polymer to form a cladding layer to obtain an optical circuit board.

However, in the conventional manufacturing method as described above, it is necessary to use a vacuum system or to perform exposure, development, and etching using photolithography techniques, and the steps are many and complicated. For this reason, it is not possible to provide the optical turning board at low cost. In addition, in methods like ■, the interface between the core and cladding is not smooth due to etching, resulting in large light propagation loss, and in methods like ■, it is necessary to take sufficient refractive index difference between the core and cladding. What cannot be done,
There were other problems.

[Purpose of the invention]

In view of the above circumstances, it is an object of the present invention to provide a method for manufacturing an optical circuit board that can produce an optical circuit board with low light propagation loss and high precision through simple steps and at low cost.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a method for manufacturing an optical circuit board in which a core serving as an optical waveguide is formed, and a groove in which the core is placed is formed on the surface of the board. Abstract: A method for manufacturing an optical circuit board, characterized in that a substrate having a shape is prepared, the groove is filled with a resin serving as a core, and then a cover constituting a part of a cladding is applied to the opening of the groove. It is said that

Hereinafter, embodiments of the present invention will be explained in detail with reference to the accompanying drawings.

FIGS. 1(a) to 1(d) show the method for manufacturing an optical circuit board according to the present invention in the order of steps. Each manufacturing process is explained below according to the drawings.

■ As shown in Figure 1(a), there is a groove in the core part.
A plate-shaped base 1 on which 1 is formed is prepared. In addition, the base 1
At least the inner wall surface of the groove 11 is mirror-finished.

The base body 1 is formed using a general thermosetting resin or a thermoplastic resin by a normal molding method. Preferred resins include highly transparent acrylic resins and polyallyl carbonate resins. Note that the mirror finishing of the inner wall surface of the groove 11 is preferably done by mirror finishing the surface of the convex part for forming the groove 11 in the molding die for molding the base 1 (thereby, it is preferable to do it at the same time as the molding). .

■ As shown in Figure 1(b), liquid resin 2 is poured into the groove 11.
Fill until it overflows. The resin 2 may be a thermosetting resin, a photocurable resin, or a thermoplastic resin whose refractive index after curing is higher than the refractive index of the base 1 and the cover 3, which is transparent in the wavelength range of propagating light, and which has small curing shrinkage. A resin or the like is selected within a desired refractive index range. Examples of such resins include epoxy resins, unsaturated polyester resins, urethane acrylate resins, epoxy acrylate resins, and modified resins thereof. Note that the resin described here may contain a monomer or oligomer component added as a curing agent and a crosslinking agent, a solvent, and the like.

■ As shown in Figure 1 (C), cover 3 is placed on the surface of base 1.
This cover 3 is attached to the base 1 by covering and pressing. At this time, the resin 2 overflowing during filling spreads into the gap between the base 1 and the cover 3. The resin 2 that has spread into this gap serves to bond the base 1 and the cover 3 together. Since the cover 3 serves as the upper cladding layer, the surface thereof in contact with the resin 2 is made smooth. An adhesive layer 2 interposed between the cover 3 and the base 1 in a portion other than the groove 11
The thickness of groove 11 is sufficiently thin (1/2
0 or more) is desirable. Adjustment of the thickness of the adhesive N21 can be easily achieved by adjusting the amount of resin filled and the pressure applied when attaching the cover. The cover 3 is preferably made of, for example, a plate-shaped, sheet-shaped, or film-shaped plastic material or glass material. cover 3
The material is selected from materials that have a lower refractive index than the core resin. Note that the cover 3 may be made of the same material as the base 1 or may be made of a different material.

(2) The resin 2 is cured to form an optical circuit board in which the core 4 is formed (FIG. 1(d)). For curing, if the resin is thermosetting, it is heated to the curing temperature, and if it is photocuring, it is irradiated with actinic light. In addition, when using a photocurable resin, the base 1 or the cover 3
It is necessary to make at least one of them transparent to active light.

Note that the inner wall surface of the groove that forms the interface between the core and the cladding and the surface of the cover have a value of 0.0% when light propagation loss is considered.
The roughness is preferably 1S or less.

Since the method for manufacturing the optical circuit board according to the present invention is as described above, no complicated process or equipment is required. Moreover, a low-loss optical circuit can be easily formed. That is, since the base body and the cover serve as the cladding, there is no need to form a new cladding layer. If the inner wall surface of the groove and the surface of the cover are mirror-finished in advance, there is no need to polish the surface of the core or the like during the manufacturing process. In addition, a wide selection of core and cladding materials is available.
It is possible to combine materials with arbitrary refractive index differences.

FIG. 2 shows an optical circuit board obtained by an embodiment of the optical circuit board manufacturing method according to the present invention, viewed diagonally from above. As shown in the figure, this optical circuit board A has a core 4 formed therein, which serves as a light waveguide, and a lens 6 on the end face of the core 4, that is, on the side wall face opposite to the face that becomes the light entrance and exit. is provided. The lens 6 is provided to enhance the optical coupling between the external optical system and the core 4. That is, the optical coupling may not be very good if the core 4 is used alone. The lens 6 is integrally formed with the base 1, and its focal point and optical axis are aligned with the center of the end surface of the core 4. In addition, in this embodiment, the core 4 is branched, and the branched core 4a
The lens 6 is not provided on the end face 4b of the base body 1, and the lens 6 is exposed on the side surface of the base body 1. By doing so, it can be directly connected to other optical waveguides. If a lens is required, it can be added later.

Since this optical circuit board A is equipped with the lens 6 as described above, it is possible to efficiently couple optical signals with the light receiving and emitting elements as an external optical system and with other leading waveguides without wasting time. can.

The optical circuit board obtained by the method for manufacturing an optical circuit board according to the present invention is used, for example, in the following manner. That is, as shown in FIG. 3, the tip of an optical fiber 43 through which light from an external optical system is guided is arranged so as to face the spherical lens 42 of the optical circuit board 40, and the light from this optical fiber 43 is guided. The light is guided from the lens 42 to the core 41, and from the core 41 to the internal optical system.

Further, as shown in FIG. 4, an optical circuit board 50 is mounted on a printed circuit board 53, and light emitted from a light emitting element 55 mounted on the printed circuit board 53 is transmitted to a cylindrical lens 5.
2 to the core 51, and from the core 51 to the external optical system. In addition, in the figure, 54 is a reflecting mirror. In this usage example, a light receiving element may be mounted on the printed circuit board 53 instead of the light emitting element.

The method for manufacturing an optical circuit board according to the present invention is not limited to the above embodiments. For example, in the above embodiment, the entire base and cover are made of a material with a lower refractive index than the resin serving as the core, but only the surfaces in contact with the core, that is, the inner wall surface of the groove and the surface of the cover, have a lower refractive index. It may be made of any material. In the above embodiment, the cover was attached to the entire surface of the base, but the cover may be provided to cover only the upper surface of the groove. In the above embodiment, the lens is integrally molded on the end surface of the base body in advance, but the lens may be attached later. It doesn't matter if you don't have a lens.

〔Effect of the invention〕

As described above, the method for manufacturing an optical circuit board according to the present invention is a method for manufacturing an optical circuit board in which a core serving as an optical waveguide is formed inside, and a groove in which the core is placed is formed on the surface. A plate-shaped substrate is prepared, and the groove is filled with resin that becomes the core, and then a cover that forms part of the cladding is applied to the opening of the groove, so that the propagation loss of light is reduced. , it is possible to manufacture optical circuit boards with high precision through simple processes and at low cost.

[Brief explanation of drawings]

Figures 1 (a) to (d) are explanatory diagrams illustrating the manufacturing method of an optical circuit board according to the present invention according to the process order, and Figure 2 is a perspective view of one embodiment of an optical circuit board obtained by the manufacturing method. 3 and 4 are side views showing examples of the use of the obtained optical circuit board. 1...Base 2...Resin 3...Cover 4...
・Core 11... Mizo Agent Patent Attorney Takehiko Matsumoto Figure 1 (a) (b) (d) Figure 2 Figure 3 Figure 4 Seishi Seisho Seisho (self-published August 5, 1986) 3. Relationship with the case of the person making the amendment Patent Applicant Address 1048 Oaza Kadoma, Kadoma City, Osaka Name (583) Representative of Matsushita Electric Works Co., Ltd. Subject Specification 7, Contents of the Amendment (11 Deleting the text "Thermoplastic resin" on page 5, line 3 of the specification.

Claims (1)

[Claims] (1) A method for manufacturing an optical circuit board in which a core that serves as an optical waveguide is formed, in which a plate-shaped substrate is prepared with a groove formed on the surface in which the core is placed, and the core is placed in the groove. 1. A method for manufacturing an optical circuit board, which comprises filling the opening of the groove with a resin, and then applying a cover constituting a part of the cladding to the opening of the groove.