JP2011028127A - Optical waveguide, optical waveguide structure, photoelectric hybrid substrate, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide having excellent durability for disconnection and excellent flexibility, and to provide an optical waveguide structure having such optical waveguide, a photoelectric hybrid substrate and electronic equipment having this optical waveguide structure. <P>SOLUTION: The optical waveguide structure 1 is a belt-like member in which an optical waveguide 6, a support film (first support layer) 2, and a cover film (second support layer) 7 are laminated. This optical waveguide structure 1 is A'>B' where A' is a bending stiffness when the optical waveguide structure 1 is bent so that the support film 2 side becomes inside and where B' is a bending stiffness when the optical waveguide structure 1 is bent in the opposite direction. Also, in the optical waveguide structure 1, at least one is different between the forming conditions of a clad layer 61 and those of a clad layer 62 and between the forming conditions of the support film 2 and those of the cover film 7. In addition, the structural materials, the average thickness, and so on are cited as the examples of the forming conditions. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical waveguide, an optical waveguide structure, an opto-electric hybrid board, and an electronic device.

  In recent years, optical communication that transports data using optical carriers has become increasingly important. In such optical communication, there is an optical waveguide as a means for guiding an optical carrier wave from one point to another point.

  For example, the optical waveguide includes a pair of cladding layers and a core layer provided between the pair of cladding layers. The core layer has a linear core portion and clad portions provided on both sides of the core portion so as to sandwich the core portion. The core part is made of a material that is substantially transparent to the light of the optical carrier wave, and the cladding layer and the cladding part are made of a material having a refractive index lower than that of the core part.

  Patent Document 1 discloses a polymer optical waveguide film having two clad layers (an upper clad layer and a lower clad layer) and a core layer formed between the clad layers using deuterated polymethyl methacrylate. It is disclosed.

  In such a polymer optical waveguide film, a core layer is formed on a lower clad layer, and then a core portion of a linear pattern is processed on a part of the core layer by photolithography and dry etching. Thereafter, a polymer optical waveguide film can be obtained by spin-coating the same polymer material as that of the lower cladding layer so as to cover the core portion, and forming the upper cladding layer covering the upper surface and side surfaces of the core portion. .

  Such a polymer optical waveguide film described in Patent Document 1 is expected to be flexible and flexible by utilizing its flexible properties.

  In addition, such a polymer optical waveguide film is often used as an optical interconnection such as an optical wiring, but there is a demand for reducing the mounting space of the optical wiring along with downsizing of electronic equipment. Therefore, the polymer optical waveguide film is required to have flexibility to withstand bending with a smaller radius of curvature.

  However, when the thickness of the polymer optical waveguide film is reduced in order to increase the flexibility of the polymer optical waveguide film, there is an increased risk of disconnection due to bending or the like. In addition, the polymer optical waveguide film functions as an optical wiring by connecting both ends thereof to a connection partner. However, if the thickness of the polymer optical waveguide film is too thin, the coupling loss at the connection portion is reduced. Will increase.

JP 2005-134862 A

  An object of the present invention is to provide an optical waveguide having excellent durability against disconnection and having excellent flexibility, an optical waveguide structure including the optical waveguide, an opto-electric hybrid board and an electronic device including the optical waveguide structure. It is to provide.

Such an object is achieved by the present inventions (1) to (15) below.
(1) a core layer including an elongated core portion and a side clad portion provided so as to be adjacent to a side surface of the core portion;
A first cladding layer laminated adjacent to one side of the core layer;
An optical waveguide having a second cladding layer laminated adjacent to the other surface side of the core layer,
The first cladding layer has a formation condition different from that of the second cladding layer,
The bending stiffness when the optical waveguide is bent so that the first cladding layer side is inward is A, and the bending stiffness when the optical waveguide is bent so that the second cladding layer side is inward is B. An optical waveguide characterized in that A> B.

  (2) The optical waveguide according to (1), wherein the formation condition is at least one of a constituent material and an average thickness.

  (3) The optical waveguide according to (1) or (2), wherein the constituent material of the first cladding layer is a material having a higher flexural modulus than the constituent material of the second cladding layer.

  (4) The optical waveguide according to any one of (1) to (3), wherein an average thickness of the first cladding layer is thicker than an average thickness of the second cladding layer.

  (5) The bending stiffness A measured by the method defined in JIS K 7106 is 1.01 to 5 when the bending stiffness B measured by the same method is 1. The optical waveguide according to any one of 4).

  (6) The said optical waveguide is an optical waveguide in any one of said (1) thru | or (5) which has a part thinner than the edge part of the longitudinal direction in positions other than the said edge part.

  (7) The optical waveguide according to (6), wherein the thickness of the core layer at the end is thicker than the thickness of the core layer at a portion other than the end.

  (8) The sum of the thickness of the first cladding layer and the thickness of the second cladding layer at the end is equal to the thickness of the first cladding layer and the second cladding at a portion other than the end. The optical waveguide according to the above (6) or (7), which is thicker than the sum of the thicknesses of the layers.

(9) a core layer including an elongated core portion and a side clad portion provided so as to be adjacent to a side surface of the core portion;
A first cladding layer laminated adjacent to one side of the core layer;
A first support layer laminated adjacent to the first cladding layer;
A second cladding layer laminated adjacent to the other surface side of the core layer;
An optical waveguide structure having a second support layer laminated adjacent to the second cladding layer,
The formation condition of the first cladding layer and the formation condition of the second cladding layer, and the formation condition of the first support layer and the formation condition of the second support layer are different,
The bending stiffness when the optical waveguide structure is bent so that the first support layer side is inside is A ′, and the optical waveguide structure is bent so that the second support layer side is inside An optical waveguide structure characterized in that A ′> B ′, where B ′ is a bending stiffness of A ′.

  (10) The optical waveguide structure according to (9), wherein the formation condition is at least one of a constituent material and an average thickness.

  (11) The optical waveguide structure according to (9) or (10), wherein the constituent material of the first support layer is a material having a higher flexural modulus than the constituent material of the second support layer.

  (12) The optical waveguide structure according to any one of (9) to (11), wherein an average thickness of the first support layer is thicker than an average thickness of the second support layer.

  (13) The bending stiffness A ′ measured by the method defined in JIS K 7106 is 1.01 to 5 when the bending stiffness B ′ measured by the same method is 1, (9) Thru | or the optical waveguide structure in any one of (12).

(14) a support substrate comprising an electrical wiring pattern;
An opto-electric hybrid board comprising the optical waveguide according to any one of (1) to (8), which is laminated on the support substrate.

  (15) An electronic apparatus comprising the opto-electric hybrid board according to (14).

  According to the present invention, an optical waveguide and an optical waveguide structure capable of bending with a small radius of curvature and efficiently using a mounting space since both high flexibility and durability against disconnection are highly compatible. The body is obtained.

  Further, by using such an optical waveguide, it is possible to obtain an opto-electric hybrid board and an electronic device that can be miniaturized and have high reliability.

1 is a perspective view showing an embodiment of an optical waveguide structure of the present invention (partially cut out and shown through). It is the XX sectional view taken on the line of FIG. It is the XX sectional view taken on the line of FIG. It is a figure (YY sectional view taken on the line of FIG. 1) for demonstrating the method to manufacture an opto-electric hybrid board using the optical waveguide structure shown in FIG. 2A is a plan view showing an extended state of the optical waveguide structure shown in FIG. 1 and FIG. 2B is a perspective view showing a bent state.

  Hereinafter, the optical waveguide, the optical waveguide structure, the opto-electric hybrid board, and the electronic apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

[Optical waveguide and optical waveguide structure]
First, an embodiment of an optical waveguide and an optical waveguide structure according to the present invention will be described.

  FIG. 1 is a perspective view showing an embodiment of an optical waveguide structure of the present invention (partially cut out and shown in a transparent manner), and FIGS. 2 and 3 are cross-sectional views taken along the line XX of FIG. . In the following description, the upper side in FIGS. 1 to 3 is referred to as “upper” and the lower side is referred to as “lower”. 1 to 3 are exaggerated in the layer thickness direction (vertical direction in each figure).

(Configuration of optical waveguide and optical waveguide structure)
An optical waveguide structure 1 shown in FIG. 1 is laminated on an optical waveguide 6 (the optical waveguide of the present invention), a support film (first support layer) 2 laminated below the optical waveguide 6, and an optical waveguide 6. It is a band-shaped member having a cover film (second support layer) 7.

  Such an optical waveguide structure 1 functions as an optical wiring member that transmits an optical signal from one end to the other end by the optical waveguide 6.

  Moreover, by peeling the support film 2 from the optical waveguide structure 1, the optical waveguide 6 and the cover film 7 excluding the support film 2 can be attached to a circuit board or the like on which an electric wiring pattern is formed. Thereby, the opto-electric hybrid board having the circuit board and the optical waveguide 6 can be easily manufactured.

Hereinafter, each part of the optical waveguide structure 1 will be described in detail.
The optical waveguide 6 is formed by laminating a cladding layer (first cladding layer) 61, a core layer 63, and a cladding layer (second cladding layer) 62 in this order from the lower side in FIG. The layer 63 is formed with a long core portion 64 and a side clad portion 65 adjacent to the core portion 64. The optical waveguide 6 shown in FIG. 1 is provided with two parallel core portions 64 and three side clad portions 65 arranged in parallel. Thereby, each core part 64 will be in the state enclosed by the side surface clad part 65 and each clad layer 61,62. Each core portion 64 shown in FIG. 1 is provided with dense dots, and each side cladding portion 65 is provided with sparse dots.

  In the optical waveguide 6 shown in FIG. 1, the light incident on the core portion 64 at one end is totally reflected at the interface between the core portion 64 and the cladding portions (the clad layers 61 and 62 and the side clad portions 65). And propagating to the other side can be taken out from the core part 64 at the other end.

  Although the refractive index of the core part 64 should just be larger than the refractive index of a clad part, it is preferable that the difference is 0.5% or more, and it is more preferable that it is 0.8% or more. On the other hand, the upper limit value may not be set, but is preferably about 5.5%. If the difference in refractive index is less than the lower limit, the effect of transmitting light may be reduced, and even if the upper limit is exceeded, no further increase in light transmission efficiency can be expected.

The refractive index difference is expressed by the following equation when the refractive index of the core portion 64 is A ″ and the refractive index of the cladding portion is B ″.
Refractive index difference (%) = | A ″ / B ″ −1 | × 100

  In the configuration shown in FIG. 1, the core portion 64 is formed in a straight line shape in plan view, but may be curved, branched or the like in the middle, and its shape is arbitrary.

  1 has a quadrangular shape such as a square or a rectangle (rectangle) in cross-sectional shape.

  The width and height of the core portion 64 are not particularly limited, but are preferably about 1 to 200 μm, more preferably about 5 to 100 μm, and still more preferably about 20 to 70 μm.

  The constituent material of the core layer 63 is not particularly limited as long as the above-described refractive index difference is generated. Specifically, acrylic resin, methacrylic resin, polycarbonate, polystyrene, epoxy resin, polyamide, polyimide, polybenzo In addition to various resin materials such as oxazole, polysilane, polysilazane, and cyclic olefin resins such as benzocyclobutene resin and norbornene resin, glass materials such as quartz glass and borosilicate glass can be used.

  Of these, norbornene resins are particularly preferable. These norbornene-based polymers include, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using a cationic palladium polymerization initiator, and other polymerization initiators ( For example, it can be obtained by any known polymerization method such as polymerization using a polymerization initiator of nickel or another transition metal).

  On the other hand, the clad layers 61 and 62 constitute clad portions located at the lower part and the upper part of the core layer 63, respectively. With such a configuration, each core portion 64 functions as a light guide path whose outer periphery is surrounded by a clad portion.

  The average thickness of the clad layers 61 and 62 is preferably about 0.1 to 1.5 times the average thickness of the core layer 63 (average height of each core portion 64). More preferably, the average thickness of the clad layers 61 and 62 is not particularly limited, but it is usually preferably about 1 to 200 μm and about 5 to 100 μm. More preferably, it is about 10 to 60 μm. Thereby, the function as a clad layer is suitably exhibited while preventing the optical waveguide 6 from becoming unnecessarily large (thickened).

  Further, as the constituent material of the cladding layers 61 and 62, for example, the same material as the constituent material of the core layer 63 described above can be used, but a norbornene polymer is particularly preferable.

  Further, when selecting the constituent material of the core layer 63 and the constituent materials of the clad layers 61 and 62, the material may be selected in consideration of the difference in refractive index between them. Specifically, in order to ensure total reflection of light at the boundary between the core portion 64 and the cladding layers 61 and 62, the material may be selected so that the refractive index of the constituent material of the core portion 64 is sufficiently large. As a result, a sufficient refractive index difference is obtained in the thickness direction of the optical waveguide 6, and light can be prevented from leaking from the respective core portions 64 to the cladding layers 61 and 62.

  From the viewpoint of suppressing light attenuation, it is also important that the adhesiveness (affinity) between the constituent material of the core layer 63 and the constituent materials of the cladding layers 61 and 62 is high.

  The support film (first support layer) 2 supports and protects / reinforces the lower surface of the optical waveguide 6. Thereby, the reliability and mechanical characteristics of the optical waveguide structure 1 can be enhanced.

  Examples of the constituent material of the support film 2 include various resin materials such as polyethylene terephthalate (PET), polyolefin such as polyethylene and polypropylene, polyimide and polyamide, and metal materials such as copper, aluminum and silver. It is done. In the case of a metal material, a metal foil is preferably used as the support film 2.

  Moreover, although the average thickness of the support film 2 is not specifically limited, It is preferable that it is about 5-200 micrometers, and it is more preferable that it is about 10-100 micrometers. Thereby, since the support film 2 has moderate rigidity, while supporting the optical waveguide 6 reliably, the moderate flexibility of the optical waveguide structure 1 is ensured.

  The support film 2 and the optical waveguide 6 are bonded or bonded, and examples of the method include thermocompression bonding, bonding with an adhesive or a pressure sensitive adhesive, and the like.

  Among these, as an adhesive layer, various hot-melt-adhesives (polyester type | system | group, modified olefin type | system | group) etc. are mentioned other than an acrylic adhesive, a urethane type adhesive agent, a silicone type adhesive agent, for example. Moreover, as a thing with especially high heat resistance, thermoplastic polyimide adhesive agents, such as a polyimide, a polyimide amide, a polyimide amide ether, a polyester imide, a polyimide ether, are used preferably. Since the adhesive layer made of such a material is relatively flexible, even if the shape of the optical waveguide structure 1 changes, the change can be freely followed. As a result, it is possible to reliably prevent peeling due to the shape change.

  The average thickness of such an adhesive layer is not particularly limited, but is preferably about 1 to 100 μm, and more preferably about 5 to 60 μm.

On the other hand, a cover film (second support layer) 7 is laminated on the upper surface of the optical waveguide 6.
The cover film 7 protects the optical waveguide 6 and supports the optical waveguide 6 from above. Thereby, the optical waveguide 6 is protected from dirt and scratches, and the reliability and mechanical characteristics of the optical waveguide structure 1 can be improved.

  The constituent material of the cover film 7 is the same as the constituent material of the support film 2, for example, various resin materials such as polyethylene terephthalate (PET), polyolefin such as polyethylene and polypropylene, polyimide, polyamide, Metal materials, such as copper, aluminum, silver, are mentioned. In the case of a metal material, a metal foil is preferably used as the cover film 7. Further, when a mirror is formed in the middle of the optical waveguide 6, light is transmitted through the cover film 7. Therefore, the constituent material of the cover film 7 is preferably substantially transparent.

  Moreover, although the average thickness of the cover film 7 is not specifically limited, It is preferable that it is about 3-50 micrometers, and it is more preferable that it is about 5-30 micrometers. By setting the thickness of the cover film 7 within the above range, the cover film 7 has sufficient light transmittance in optical communication and sufficient rigidity to reliably protect the optical waveguide 6.

  Note that the cover film 7 and the optical waveguide 6 are bonded or bonded, and examples of the method include thermocompression bonding, bonding with an adhesive or a pressure sensitive adhesive, and the like. Of these, the adhesive described above can be used.

  The optical waveguide structure 1 having the support film 2, the optical waveguide 6, and the cover film 7 as described above has sufficient flexibility (flexibility) as a whole, and can be bent without being bent. Become.

  By the way, the optical waveguide structure 1 is curved so that the support film 2 side (cladding layer 61) side is inside, and conversely, the cover film 7 side (cladding layer 62) side is curved inside. Although it is possible, these are easy to bend.

  Specifically, the optical waveguide structure 1 has a bending stiffness (strength) when bent so that one of the support film 2 side and the cover film 7 side is inside, and the other is inside. The bending stiffness when bent is different. The bending stiffness when the optical waveguide structure 1 is bent so that the support film 2 side is inside is A ′, and the bending stiffness when the optical waveguide structure 1 is bent so that the cover film 7 side is inside is A ′. When B ′, A ′> B ′.

  That is, such an optical waveguide structure 1 can be bent relatively easily in a bending direction in which the bending stiffness is B ′, and thus has excellent flexibility. On the other hand, the optical waveguide structure 1 has a relatively high rigidity because it is difficult to bend in the bending direction in which the bending stiffness is A ′.

  Therefore, the optical waveguide structure 1 is excellent in flexibility in one direction by limiting the direction in which it can be easily bent, and has durability against bending by sacrificing the ease in bending in the opposite direction. keeping. Thereby, the optical waveguide structure 1 can be highly compatible with flexibility and durability against disconnection. For this reason, the optical waveguide structure 1 enables bending with a small radius of curvature and enables efficient use of the mounting space. Even if bending and stretching are repeated, the optical waveguide structure 1 can reliably prevent the disconnection.

  Further, since the optical waveguide structure 1 has a certain degree of rigidity, when the optical waveguide structure 1 is connected to various optical components such as a light emitting element, a light receiving element, an optical fiber, and an optical connector, the workability of the connection work is improved. Will improve. For example, when the optical waveguide structure 1 is inserted into the optical connector, it is possible to reliably prevent the optical waveguide structure 1 from being bent or broken along with the insertion work. Improvement is achieved.

  In this embodiment, the cladding layer 61 corresponds to the first cladding layer, and the cladding layer 62 corresponds to the second cladding layer. The support film 2 corresponds to the first support layer, and the cover film 7 corresponds to the second support layer.

  In such an optical waveguide structure 1, (I) between the formation conditions of the cladding layer 61 and the formation conditions of the cladding layer 62, and (II) the formation conditions of the support film 2 and the formation conditions of the cover film 7. At least one of them is different.

  Therefore, the difference in bending stiffness due to the bending direction as described above is mainly manifested by having at least one of the difference (I) and difference (II) in the formation conditions described above. I can say that. Hereinafter, the difference (I) and the difference (II) will be described in detail.

(I)
In the difference (I), the formation conditions of the cladding layer 61 and the formation conditions of the cladding layer 62 in the optical waveguide 6 of the optical waveguide structure 1 are different. For example, when the optical waveguide structure 1 is bent, the cladding layer 61 is deformed so as to be compressed along with the bending operation when the optical waveguide structure 1 is bent. The layer 62 is deformed so as to be pulled along with the bending operation. Therefore, in the above case, the formation conditions of the clad layer 61 and the clad layer 62 may be appropriately selected in consideration of such different types of deformation (compression deformation or tensile deformation).

  Examples of the formation conditions include the constituent materials of the clad layer 61 and the clad layer 62, the respective average thicknesses, the presence / absence of processing for each layer, and the like. Among these, by making at least one of the constituent material and the average thickness different, the above-described effects can be exerted more easily and reliably on the optical waveguide structure 1.

  In the present embodiment, the difference (I) is set so that the bending stiffness A ′ is larger than the bending stiffness B ′.

  Hereinafter, regarding the difference (I), (Ia) when the constituent material of the cladding layer 61 and the constituent material of the cladding layer 62 are different, and (Ib) the average thickness of the cladding layer 61 and the average of the cladding layer 62 The description will be divided into cases where the thickness is different.

(Ia) When the constituent material of the cladding layer 61 and the constituent material of the cladding layer 62 are different When the thickness of the cladding layer 61 and the thickness of the cladding layer 62 are substantially the same, the constituent material of the cladding layer 61 is A material having a higher flexural modulus than the constituent material of the cladding layer 62 is preferable. Thereby, the clad layer 61 becomes difficult to bend as compared with the clad layer 62, and the flexibility becomes low. As a result, even if the optical waveguide structure 1 is bent so that the cladding layer 61 (support film 2) is on the inner side, the inner cladding layer 61 cannot sufficiently absorb the compressive force applied thereto. Therefore, it cannot be deformed so much as compared with the clad layer 62. This is because in a general resin material, when a certain force is applied, the amount of deformation accompanying compression is smaller than the amount of deformation accompanying pulling. For this reason, when the optical waveguide structure 1 is bent so that the clad layer 61 is inside, the flexibility of the clad layer 61 is relatively lower than that of the clad layer 62. It becomes difficult to bend in this direction easily.

  On the other hand, as for the clad layer 62, the bending elastic modulus of the constituent material is made smaller than the bending elastic modulus of the constituent material of the clad layer 61. Become. Therefore, when the optical waveguide structure 1 is bent in the opposite direction to that described above, that is, so that the cladding layer 62 (cover film 7) is on the inside, the cladding layer 61 located on the outside is the cladding layer 62. Is relatively higher than that of the cladding layer 61, the amount of deformation is relatively large even when compressed. As a result, the optical waveguide structure 1 can be easily bent in this direction.

  Further, the clad layer 61 located on the outer side is pulled, but as described above, when a general resin material is pulled, it is relatively easily deformed when it is pulled. As a result, it is possible to prevent the bending of the optical waveguide structure 1 from being hindered.

  On the other hand, the cladding layer 61 ensures the relatively high rigidity and bending resistance of the optical waveguide structure 1, and as a result, the optical waveguide structure 1 has sufficient durability even when the bending operation is repeated. It will have.

  As described above, the optical waveguide structure 1 is easily bent in the direction in which the clad layer 62 is on the inner side. The clad layer 61 makes the optical waveguide structure 1 have high rigidity and high bending resistance, and has sufficient durability. That is, the optical waveguide structure 1 can achieve both high flexibility and durability against disconnection.

  Note that the flexural modulus of the constituent material of each of the cladding layers 61 and 62 varies depending on the molecular weight, the synthesis condition, the film forming condition, etc. as well as the kind of the constituent material. For example, even if the kind of resin material is the same, the flexural modulus tends to increase as the molecular weight increases. Therefore, in this case, the molecular weight of the resin material may be adjusted so that the flexural modulus of the constituent material of the clad layer 61 is larger than the flexural modulus of the constituent material of the clad layer 62.

  Moreover, it is preferable to use the method prescribed | regulated to JISK7171 (how to obtain | require a plastic-bending characteristic) as a measuring method of a bending elastic modulus. Thereby, the bending elastic modulus can be measured with high accuracy.

  When each bending elastic modulus is measured by this method, the bending elastic modulus of the constituent material of the cladding layer 61 is preferably 1.01 to 5 when the bending elastic modulus of the constituent material of the cladding layer 62 is 1. 1.05 to 4 is more preferable, and 1.1 to 3 is even more preferable. If there is such a relationship between the bending elastic moduli of the constituent materials between the clad layers 61 and 62, the optical waveguide structure 1 can achieve a particularly high degree of both flexibility and durability against disconnection.

  Further, the bending elastic modulus of the constituent material of the clad layer 62 is preferably about 50 MPa to 500 GPa, more preferably about 100 MPa to 300 GPa, and about 200 MPa to 200 GPa when measured by the method described above. Is more preferable.

(Ib) When the average thickness of the cladding layer 61 and the average thickness of the cladding layer 62 are different When the constituent material of the cladding layer 61 and the constituent material of the cladding layer 62 are the same, the average thickness of the cladding layer 61 The thickness is preferably larger than the average thickness of the cladding layer 62. Thereby, the clad layer 61 becomes difficult to bend as compared with the clad layer 62, and the flexibility becomes low. As a result, even if the optical waveguide structure 1 is bent so that the cladding layer 61 (support film 2) is on the inner side, the inner cladding layer 61 cannot sufficiently absorb the compressive force applied thereto. Therefore, it cannot be deformed so much as compared with the clad layer 62. For this reason, the optical waveguide structure 1 cannot be easily bent in this direction.

  On the other hand, as a result of making the average thickness of the clad layer 62 thinner than the average thickness of the clad layer 61, the clad layer 62 is more easily bent and more flexible than the clad layer 61. Therefore, when the optical waveguide structure 1 is bent in the opposite direction to that described above, that is, so that the cladding layer 62 (cover film 7) is on the inside, the cladding layer 61 located on the outside is the cladding layer 62. Therefore, the amount of deformation accompanying compression is relatively large. As a result, the optical waveguide structure 1 can be easily bent in this direction.

  As described above, the optical waveguide structure 1 is easily bent in the direction in which the clad layer 62 is on the inner side. The clad layer 61 makes the optical waveguide structure 1 have high rigidity and high bending resistance, and has sufficient durability. That is, the optical waveguide structure 1 can achieve both high flexibility and durability against disconnection.

  The average thickness of the cladding layer 61 is preferably 1.01 to 5, more preferably 1.05 to 4, when the average thickness of the cladding layer 62 is 1. More preferably, it is ~ 3. If the average thickness between the clad layers 61 and 62 has such a relationship, the optical waveguide structure 1 can achieve both high flexibility and durability against disconnection.

  Regarding the difference (I), the constituent material and the average thickness may be different from each other between the cladding layer 61 and the cladding layer 62, and at least one of the constituent material and the average thickness Other formation conditions (for example, presence or absence of groove processing) may be different from each other. That is, in the former case, the bending elastic modulus of the constituent material of the cladding layer 61 is larger than that of the constituent material of the cladding layer 62, and the average thickness of the cladding layer 61 is larger than the average thickness of the cladding layer 62. In the latter case, for example, the bending elastic modulus of the constituent material of the cladding layer 61 is larger than that of the constituent material of the cladding layer 62 and the cladding layer 62 is grooved, A case where the average thickness is larger than the average thickness of the clad layer 62 and the clad layer 62 is grooved may be mentioned. Note that the present invention is not limited to the above case as long as the bending stiffness of the entire optical waveguide structure 1 satisfies the magnitude relationship (A ′> B ′).

(II)
In the difference (II), the formation conditions of the support film 2 and the formation conditions of the cover film 7 in the optical waveguide structure 1 are different. If there is such a difference, for example, if the support film 2 is inside when the optical waveguide structure 1 is bent, the support film 2 is deformed so as to be compressed along with the bending operation, The film 7 is deformed so as to be pulled along with the bending operation. Therefore, in the case described above, the formation conditions of the support film 2 and the cover film 7 may be appropriately selected in consideration of the different types of deformation.

  As this formation condition, each constituent material of support film 2 and cover film 7, each average thickness, the existence of processing to each layer, etc. are mentioned. Among these, by making at least one of the constituent material and the average thickness different, the above-described effects can be easily and reliably exerted on the optical waveguide structure 1.

  In the present embodiment, the difference (II) is set so that the bending stiffness A ′ is larger than the bending stiffness B ′.

  Hereinafter, regarding the difference (II), (II-a) the case where the constituent material of the support film 2 and the constituent material of the cover film 7 are different, and (II-b) the average thickness of the support film 2 and the average of the cover film 7 The description will be divided into cases where the thickness is different.

(II-a) When the constituent material of the support film 2 and the constituent material of the cover film 7 are different When the thickness of the support film 2 and the thickness of the cover film 7 are substantially the same, the constituent material of the support film 2 is A material having a higher flexural modulus than the constituent material of the cover film 7 is preferable. Thereby, the support film 2 becomes difficult to bend compared with the cover film 7, and flexibility becomes low. As a result, even if the optical waveguide structure 1 is bent so that the support film 2 is on the inner side, the support film 2 positioned on the inner side cannot sufficiently absorb the compressive force applied thereto, and the cover film 7 It cannot be deformed to a great extent. This is because in a general resin material, when a certain force is applied, the amount of deformation accompanying compression is smaller than the amount of deformation accompanying pulling. For this reason, when the optical waveguide structure 1 is bent so that the support film 2 is on the inside, the flexibility of the support film 2 is relatively lower than that of the cover film 7, so the deformation amount due to compression is also compared. Therefore, it cannot be easily bent in this direction.

  On the other hand, as for the cover film 7, the bending elastic modulus of the constituent material is made smaller than the bending elastic modulus of the constituent material of the support film 2. Become. Therefore, when the optical waveguide structure 1 is bent in the opposite direction to that described above, that is, so that the cover film 7 is on the inside, the support film 2 positioned on the outside supports the flexibility of the cover film 7. Since the film 2 is relatively higher than the film 2, the amount of deformation is relatively large even if the film 2 is compressed. As a result, the optical waveguide structure 1 can be easily bent in this direction.

  Further, the support film 2 positioned on the outside is pulled, but with a general resin material, as described above, it is relatively easily deformed when pulled compared to when compressed. As a result, it is possible to prevent the bending of the optical waveguide structure 1 from being hindered.

  On the other hand, the support film 2 ensures the relatively high rigidity and bending resistance of the optical waveguide structure 1, and as a result, the optical waveguide structure 1 has sufficient durability even when the bending operation is repeated. It will have.

  As described above, the optical waveguide structure 1 is easily bent in the direction in which the cover film 7 is on the inside. The support film 2 makes the optical waveguide structure 1 have high rigidity and high bending resistance, and has sufficient durability. That is, the optical waveguide structure 1 can achieve both high flexibility and durability against disconnection.

  Note that the flexural modulus of the constituent material of the support film 2 and the cover film 7 varies depending on the molecular weight, the synthesis conditions, the film forming conditions, as well as the types of the constituent materials. For example, even if the kind of resin material is the same, the flexural modulus tends to increase as the molecular weight increases. Therefore, the molecular weight of the resin material may be adjusted so that the flexural modulus of the constituent material of the support film 2 is larger than the flexural modulus of the constituent material of the cover film 7.

  Moreover, it is preferable to use the method prescribed | regulated to JISK7171 as a measuring method of a bending elastic modulus. Thereby, the bending elastic modulus can be measured with high accuracy.

  When each bending elastic modulus is measured by this method, the bending elastic modulus of the constituent material of the support film 2 is preferably 1.01 to 5 when the bending elastic modulus of the constituent material of the cover film 7 is 1. 1.05 to 4 is more preferable, and 1.1 to 3 is even more preferable. If such a relationship exists in the bending elastic modulus of the constituent material between the support film 2 and the cover film 7, the optical waveguide structure 1 can be particularly highly compatible with flexibility and durability against disconnection.

  Further, the flexural modulus of the constituent material of the cover film 7 is preferably about 50 MPa to 500 GPa, more preferably about 100 MPa to 300 GPa, and about 200 MPa to 200 GPa when measured by the above-described method. Is more preferable.

(II-b) When the average thickness of the support film 2 is different from the average thickness of the cover film 7 When the constituent material of the support film 2 and the constituent material of the cover film 7 are the same, the average thickness of the support film 2 The thickness is preferably thicker than the average thickness of the cover film 7. Thereby, the support film 2 becomes difficult to bend compared with the cover film 7, and flexibility becomes low. As a result, even if the optical waveguide structure 1 is bent so that the support film 2 is on the inner side, the support film 2 positioned on the inner side cannot sufficiently absorb the compressive force applied thereto, and the cover film 7 It cannot be deformed to a great extent. For this reason, the optical waveguide structure 1 cannot be easily bent in this direction.

  On the other hand, as a result of making the average thickness of the cover film 7 thinner than the average thickness of the support film 2, it becomes easier to bend than the support film 2, and the flexibility is increased. Therefore, when the optical waveguide structure 1 is bent in the opposite direction to that described above, that is, so that the cover film 7 is on the inside, the support film 2 positioned on the outside supports the flexibility of the cover film 7. Since it is relatively higher than film 2, the amount of deformation accompanying compression is relatively large. As a result, the optical waveguide structure 1 can be easily bent in this direction.

  As described above, the optical waveguide structure 1 is easily bent in the direction in which the cover film 7 is on the inside. The support film 2 makes the optical waveguide structure 1 have high rigidity and high bending resistance, and has sufficient durability. That is, the optical waveguide structure 1 can achieve both high flexibility and durability against disconnection.

  In addition, when the average thickness of the cover film 7 is 1, the average thickness of the support film 2 is preferably 1.01 to 5, more preferably 1.05 to 4, and 1.1. More preferably, it is ~ 3. If the average thickness between the support film 2 and the cover film 7 has such a relationship, the optical waveguide structure 1 can achieve both high flexibility and durability against disconnection.

  Regarding the difference (II), the constituent material and the average thickness may be different from each other between the support film 2 and the cover film 7, and at least one of the constituent material and the average thickness is different from that. Other formation conditions (for example, presence or absence of groove processing) may be different from each other. That is, in the former case, the flexural modulus of the constituent material of the support film 2 is larger than that of the cover film 7 and the average thickness of the support film 2 is thicker than the average thickness of the cover film 7. In the latter case, for example, the bending elastic modulus of the constituent material of the support film 2 is larger than the constituent material of the cover film 7 and the cover film 7 is grooved. The case where an average thickness is thicker than the average thickness of the cover film 7, and the groove processing is given to the cover film 7 is mentioned. Note that the present invention is not limited to the above case as long as the bending stiffness of the entire optical waveguide structure 1 satisfies the magnitude relationship (A ′> B ′).

  Although the difference (I) and the difference (II) have been described above, the difference may be a combination of these differences. As an example of the combination, the formation conditions of the clad layer 61 and the formation conditions of the clad layer 62 are different as described above, and the formation conditions of the support film 2 and the formation conditions of the cover film 7 are also different as described above. Such an optical waveguide structure 1 is mentioned.

  By the way, as described above, the optical waveguide structure 1 is light so that the bending stiffness when the optical waveguide structure 1 is bent so that the support film 2 side is inward is A ′ and the cover film 7 side is inward. When B ′ is a bending stiffness when the waveguide structure 1 is bent, A ′> B ′, the bending stiffness may be measured by any method.

  For example, as a measuring method, it is preferable to use a method defined in JIS K 7106 (plastic bending stiffness test method by cantilever). Thereby, bending stiffness can be measured with high accuracy.

  When each bending stiffness is measured by this method, the bending stiffness A ′ is preferably 1.01 to 5, more preferably 1.05 to 4, when the bending stiffness B ′ is 1. More preferably, it is 1.1-3. The optical waveguide structure 1 having such a bending stiffness can achieve both high flexibility and durability against disconnection.

  Further, the bending stiffness B 'is preferably about 20 to 500 MPa, more preferably about 50 to 300 MPa when measured by the method described above. As a result, the optical waveguide structure 1 can be bent with a particularly small radius of curvature, and has sufficient durability even if the bending and extension are repeated.

Here, FIG. 2 and FIG. 3 are sectional views taken along line XX of the optical waveguide structure 1 shown in FIG.
In the optical waveguide structure 1, as shown in detail in FIG. 2A, the thickness of both end portions 66 in the longitudinal direction is thicker than the thickness of the central portion (portion other than both end portions) 67. Thereby, in the optical waveguide structure 1, the flexibility at the center portion 67 is particularly high, and the rigidity at both end portions 66 is particularly high. As a result, the optical waveguide structure 1 can be bent with a small radius of curvature at the central portion 67, and both end portions 66 can be reliably connected to an optical component such as an optical connector.

  Further, in the optical waveguide structure 1 shown in FIG. 2A, the thickness of the core layer 63 at both end portions 66 is larger than the thickness of the core layer 63 at the central portion 67. As a result, the numerical aperture at both end portions 66 is increased, and the coupling loss when the optical waveguide structure 1 is connected to the optical connector can be reduced.

  On the other hand, in the optical waveguide structure 1 shown in FIG. 2A, the sum of the thickness of the clad layer 61 and the thickness of the clad layer 62 at both ends 66 is equal to the thickness of the clad layer 61 and the clad layer 62 at the center. It is almost equal to the sum of the thickness.

  In the optical waveguide structure 1 shown in FIG. 2A, the thickness of both end portions 66 is thicker than the thickness of the central portion 67. The thickness gradually changes so as to smoothly connect the thickness of the portion 66 and the thickness of the central portion 67. Since the thickness change in the vicinity of the boundary is moderated as described above, the stress generated along with the bending of the optical waveguide structure 1 is concentrated in the vicinity of the boundary between the both end portions 66 and the central portion 67. Can be prevented. As a result, the optical waveguide structure 1 has excellent durability against disconnection.

  Here, FIGS. 2B, 2C, and 3 show other configuration examples of the optical waveguide structure 1. FIG. 2 (b), 2 (c) and 3 are different from the optical waveguide structure 1 shown in FIG. 2 (a) except that the structures of both end portions 66 are different. It is the same.

  In the optical waveguide structure 1 shown in FIG. 2B, the thickness of both end portions 66 is thicker than the thickness of the central portion 67 as in FIG. The sum of the thickness of the layer 61 and the thickness of the cladding layer 62 is larger than the sum of the thickness of the cladding layer 61 and the thickness of the cladding layer 62 in the central portion 67. Thereby, the rigidity in the both ends 66 can be further increased.

  In addition, in the optical waveguide structure 1 shown in FIG. 2C, the thickness of both end portions 66 is thicker than the thickness of the central portion 67 as in FIG. The sum of the thickness of the layer 61 and the thickness of the cladding layer 62 is thicker than the sum of the thickness of the cladding layer 61 and the thickness of the cladding layer 62 in the center. On the other hand, the thickness of the core layer 63 is constant throughout the optical waveguide structure 1.

  Further, the optical waveguide structure 1 shown in FIG. 3A is obtained by flattening the lower surface of the optical waveguide structure 1 shown in FIG.

  That is, as described above, the optical waveguide structure 1 shown in FIG. 2A is thick so that the core layer 63 at both ends 66 protrudes upward and downward, and as a result, The total thickness at both ends 66 is also thicker so as to project both upward and downward.

  On the other hand, the optical waveguide structure 1 shown in FIG. 3A is thick so that the core layer 63 at both end portions 66 protrudes upward only. The thickness is also thick so as to protrude only upward.

  Similarly, the optical waveguide structure 1 shown in FIG. 3B is obtained by flattening the lower surface of the optical waveguide structure 1 shown in FIG.

  Further, the optical waveguide structure 1 shown in FIG. 3C is obtained by flattening the lower surface of the optical waveguide structure 1 shown in FIG.

  Also in the optical waveguide structure 1 shown in FIG. 3, the rigidity at both end portions 66 is higher than that of the central portion 67. Further, the optical waveguide structure 1 shown in FIG. 3 has an advantage that it is easy to manufacture because the structure is simpler than that shown in FIG.

  The optical waveguide structure 1 shown in FIGS. 2 and 3 as described above has excellent rigidity at both end portions 66 without sacrificing excellent flexibility at the central portion 67. Therefore, the optical waveguide structure 1 can be reliably connected to an optical component such as an optical connector.

  In the above description, the optical waveguide structure 1 has been described in which the bending stiffness when bent in one direction is different from the bending stiffness when bent in the other direction. When the optical waveguide 6 is omitted, as in the case of the optical waveguide structure 1, the bending stiffness when bent in one direction is different from the bending stiffness when bent in the other direction. It is the feature.

  That is, when such an optical waveguide 6 is used alone, the bending stiffness when the optical waveguide 6 is bent so that the clad layer 61 side is inward is A, and the optical waveguide 6 is so arranged that the clad layer 62 side is inward. A> B, where B is the bending stiffness when bent.

  Since such an optical waveguide 6 can be bent relatively easily in a bending direction in which the bending stiffness is B, it has excellent flexibility. On the other hand, the optical waveguide 6 has relatively high rigidity because it is relatively difficult to bend in the bending direction in which the bending stiffness is A.

  Therefore, the optical waveguide 6 has excellent flexibility in one direction by limiting the direction in which it can be easily bent, and maintains durability against bending by sacrificing ease of bending in the opposite direction. ing. Thereby, the optical waveguide 6 can be highly compatible with flexibility and durability against disconnection.

  In order to cause a difference in bending stiffness depending on the bending direction as described above, the formation conditions of the cladding layer 61 and the formation conditions of the cladding layer 62 are made different as described above as the difference (I). do it.

  Further, when the bending stiffness of the optical waveguide 6 is measured by the method defined in JIS K 7106, the bending stiffness A is preferably 1.01 to 5 when the bending stiffness B is 1, and 1.05 to 1.05. 4 is more preferable, and 1.1 to 3 is even more preferable. The optical waveguide 6 having such bending stiffness can achieve both high flexibility and durability against breakage.

  Further, the bending stiffness B is preferably about 20 to 500 MPa, and more preferably about 50 to 300 MPa when measured by the above-described method. As a result, the optical waveguide 6 can be bent with a particularly small radius of curvature, and has sufficient durability even if the bending and extension are repeated.

(Optical waveguide and optical waveguide structure manufacturing method)
Next, an example of a method for manufacturing the optical waveguide 6 and the optical waveguide structure 1 will be described.

  The optical waveguide structure 1 is manufactured by preparing a support film 2, an optical waveguide 6, and a cover film 7 and laminating them.

  The optical waveguide 6 is manufactured by preparing a clad layer 61, a core layer 63, and a clad layer 62, and laminating them.

First, a method for manufacturing the optical waveguide 6 will be described.
In the manufacturing method of the optical waveguide 6, it is necessary to manufacture the optical waveguides 6 so that portions having different refractive indexes are in physical and optical contact. Specifically, it is necessary to form the side clad portion 65 and the clad layers 61 and 62 so as to be in close contact with the core portion 64 without any gap.

  As a specific manufacturing method of the clad layer 61, the core layer 63, and the clad layer 62, a composition for forming each layer is applied on a base material to form a liquid film, and then the base material is ventilated. In the table, the uneven portion on the surface of the liquid film is leveled and the solvent is evaporated (desolvent).

  Examples of the coating method for forming the liquid film include a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method.

  Further, as shown in FIGS. 2B and 2C, when the thicknesses of the clad layer 61 and the clad layer 62 at both end portions 66 of the optical waveguide 6 are partially increased, only this portion is separately provided. The composition for forming may be applied or dripped to partially increase the thickness. With such a method, it can be expected that the applied or dropped forming composition gradually wets and spreads from both end portions 66 toward the central portion 67. For this reason, finally, the change in thickness naturally becomes gentle between the thickness of the both end portions 66 and the thickness of the central portion 67.

  Note that, as shown in FIGS. 2A and 2B, the same method as described above can also be used when partially increasing the thickness at both end portions 66 of the core layer 63.

  In addition, when the optical waveguide 6 shown in FIG. 3 is manufactured, it is only necessary to increase the thickness of both end portions 66 only on the upper surface side, so that the manufacturing is easier than the optical waveguide 6 shown in FIG. .

  Further, when the thickness of the both end portions 66 of the optical waveguide 6 is partially increased, in other words, when the thickness of the central portion 67 is partially decreased, in addition to the above-described method, the thickness is uniform. After producing the optical waveguide 6 so as to have a sufficient thickness, the optical waveguide 6 may be pulled along the longitudinal direction while heating the central portion 67. Thereby, the heated central portion 67 is softened, and tensile stress is applied thereto, so that the central portion 67 is extended. As a result, the thickness of the central portion 67 can be partially made thinner than the thickness of the both end portions 66.

  In addition, the thickness of both end portions 66 of the optical waveguide 6 can be partially increased by a method using a mold.

  In addition, as a method for forming the core portion 64 and the side cladding portion 65 in the same layer (core layer 63), for example, a photo bleaching method, a photolithography method, a direct exposure method, a nanoimprinting method, a monomer Examples include the diffusion method.

  Then, the prepared cladding layer 61, core layer 63, and cladding layer 62 are pressure-bonded to each other. Thereby, the clad layer 61, the core layer 63, and the clad layer 62 are joined and integrated, and the optical waveguide 6 is obtained.

Next, a method for manufacturing the optical waveguide structure 1 will be described.
In the manufacturing method of the optical waveguide structure 1, the support film 2 and the optical waveguide 6 and the optical waveguide 6 and the cover film 7 are bonded or bonded, respectively.

  Here, when the opto-electric hybrid board is manufactured by peeling the support film 2 from the finally obtained optical waveguide structure 1 and bonding the remaining part to the circuit board, the support film 2 is easily peeled off. It is preferable that the adhesive force between the support film 2 and the optical waveguide 6 is adjusted.

  The optical waveguide structure 1 as described above functions as an optical wiring by connecting a light emitting element to one end and connecting a light receiving element to the other end. Such an optical waveguide structure 1 can reliably transmit and receive an optical signal in a bent state using its excellent flexibility.

  In addition, since it has excellent durability against disconnection, even when the separation distance between the light emitting element and the light receiving element changes repeatedly, the optical waveguide structure 1 repeats the bending state and the extending state, thereby The function as wiring is reliably maintained over a long period of time.

[Opto-electric hybrid board and electronic equipment]
FIG. 4 is a view (a cross-sectional view taken along line YY in FIG. 1) for explaining a method of manufacturing an opto-electric hybrid board using the optical waveguide structure shown in FIG.

  The optical waveguide structure 1 having the cover film 7, the optical waveguide 6, and the support film 2 as described above is formed after the support film 2 of the optical waveguide structure 1 is peeled off as shown in FIG. As shown in FIG. 4B, the peeling surface is attached to the circuit board 11 including the electric wiring pattern 12. As a result, the opto-electric hybrid board 10 shown in FIG. 4C, which includes the cover film 7, the optical waveguide 6, and the circuit board 11, is obtained.

  An electric wiring pattern 12 is provided on the lower surface of the circuit board 11 shown in FIG. 4. In addition, the circuit board 11 is in charge of electronic components such as a light emitting element, a light receiving element, and an IC (integrated circuit) (not shown) and external connection. Terminals and the like are also provided, and the electric wiring pattern 12 electrically connects these electronic components or between the electronic components and the terminals. Thereby, electric power is supplied to each electronic component via the electric wiring pattern 12, and an electric signal is exchanged between the electronic components.

  The light emitting element converts an electrical signal into an optical signal and enters the optical waveguide 6, and the light receiving element receives the optical signal transmitted through the optical waveguide 6 and converts it into an electrical signal. By performing mutual conversion between the electrical signal and the optical signal in this way, the electrical wiring can be replaced by the optical waveguide 6, and as a result, the opto-electric hybrid board 10 that enables high-speed and low-noise signal processing is provided. can get.

  As the circuit board 11, a flexible board having a relatively high flexibility or a rigid board having a relatively high rigidity is mainly used.

  Among these, specific examples of the flexible substrate include a polyester copper-clad film substrate, a polyimide copper-clad film substrate, and an aramid copper-clad film substrate.

  On the other hand, as specific examples of rigid substrates, glass substrate copper-clad laminates such as glass cloth and epoxy copper-clad laminates, composite copper-clad laminates such as glass nonwoven fabric and epoxy copper-clad laminates, polyetherimide resin substrates, Examples thereof include organic substrates such as heat-resistant and thermoplastic substrates such as polyetherketone resin substrates and polysulfone-based resin substrates, and ceramic substrates such as alumina substrates, aluminum nitride substrates, and silicon carbide substrates.

  In such an opto-electric hybrid board 10, as described above, the optical signal transmitted through the optical waveguide 6 is converted into an electrical signal in the optical device and transmitted to the electrical wiring. As a result, the optical waveguide 6 can transmit information at a higher speed and with a larger capacity than the conventional electric wiring. Therefore, for example, by applying this opto-electric hybrid board 10 to a bus or the like that connects between an arithmetic device such as a CPU or LSI and a storage device such as a RAM, the performance of the entire system is improved and electromagnetic noise is generated. Can be suppressed.

  Here, when a flexible board is used as the circuit board, the entire opto-electric hybrid board 10 is also flexible, and can take an extended state and a bent state obtained by bending it.

  5A is a plan view showing an extended state of the optical waveguide structure shown in FIG. 1, and FIG. 5B is a perspective view showing a bent state.

  An opto-electric hybrid board 10 ′ shown in FIG. 5 includes a circuit board 13 made of a strip-like flexible board, the optical waveguide structure 1 stacked on one surface side of the circuit board 13, and both end portions 131 of the circuit board 13. And two circuit boards 14 made of a rigid board fixed to the other surface side.

  The circuit board 13 is provided with a plurality of terminals 132 connected to an electric wiring pattern (not shown).

  Furthermore, both ends of the optical waveguide structure 1 are fixed to both ends 131 of the circuit board 13. On the other hand, other than both ends of the optical waveguide structure 1 are not fixed to the circuit board 13.

  When such an opto-electric hybrid board 10 ′ is extended as shown in FIG. 5A, the optical waveguide structure 1 is also extended along the extended circuit board 13.

  On the other hand, as shown in FIG. 5B, the optical waveguide structure 1 is also bent along the bent circuit board 13 even in a bent state in which the optical waveguide structure 1 is bent so as to be folded back in the vicinity of the center portion thereof. It becomes a state. At this time, the radius of curvature of the circuit board 13 and the radius of curvature of the optical waveguide structure 1 should inevitably differ from each other. However, as described above, the optical waveguide structure 1 has a circuit board only at both ends. Since it is fixed to 13, it is possible to absorb the deviation of the curvature radius as described above.

  As a result, even when the opto-electric hybrid board 10 ′ repeats such an extended state and a bent state, the optical waveguide structure 1 can be deformed so as to follow the deformation of the circuit board 13. The function as an optical wiring can be reliably maintained.

  Such opto-electric hybrid boards 10 and 10 'may be mounted on electronic devices that transmit large volumes of data at high speed, such as mobile phones, game machines, personal computers, televisions, home servers, and the like. As described above, the electronic device (the electronic device of the present invention) including the opto-electric hybrid board 10 or 10 '(the opto-electric hybrid substrate of the present invention) exhibits high performance excellent in internal information processing speed. .

  Since the opto-electric hybrid board 10 'has excellent flexibility, the mounting space can be made more efficient by being mounted in an electronic device in a bent state. For this reason, the electronic device can be further reduced in size.

  In addition, since the opto-electric hybrid board 10 'can be in the bent state and the extended state as described above, for example, in the hinge part of an electronic device such as a mobile phone having a hinge part, a game machine, a PDA, or a notebook computer. It can use suitably. For example, in a mobile phone, when two points via a hinge part are connected by an opto-electric hybrid board 10 ′, when the hinge part of the mobile phone is closed, the opto-electric hybrid board 10 ′ takes a bent state, and the hinge part is When it is opened, the opto-electric hybrid board 10 'is in an extended state.

  In this way, the opto-electric hybrid board 10 'can maintain the electrical connection and the optical connection between the two points sandwiching the movable part over a long period of time. Therefore, the reliability of the mobile phone including the opto-electric hybrid board 10 'can be improved.

  As described above, the embodiments of the optical waveguide, the optical waveguide structure, the opto-electric hybrid board, and the electronic device of the present invention have been described. However, the present invention is not limited thereto, and for example, the optical waveguide, the optical waveguide structure, Each part constituting the opto-electric hybrid board can be replaced with any part that can exhibit the same function. Moreover, arbitrary components may be added.

DESCRIPTION OF SYMBOLS 1 Optical waveguide structure 2 Support film 6 Optical waveguide 61, 62 Clad layer 63 Core layer 64 Core part 65 Side clad part 66 Both ends 67 Center part 7 Cover film 10, 10 'Opto-electric hybrid board 11, 13, 14 Circuit board 12 Electrical Wiring Pattern 131 Both Ends 132 Terminals

Claims (15)

A core layer including an elongated core portion and a side clad portion provided so as to be adjacent to a side surface of the core portion;
A first cladding layer laminated adjacent to one side of the core layer;
An optical waveguide having a second cladding layer laminated adjacent to the other surface side of the core layer,
The first cladding layer has a formation condition different from that of the second cladding layer,
The bending stiffness when the optical waveguide is bent so that the first cladding layer side is inward is A, and the bending stiffness when the optical waveguide is bent so that the second cladding layer side is inward is B. An optical waveguide characterized in that A> B.   The optical waveguide according to claim 1, wherein the formation condition is at least one of a constituent material and an average thickness.   3. The optical waveguide according to claim 1, wherein a constituent material of the first clad layer is a material having a bending elastic modulus larger than that of the constituent material of the second clad layer.   4. The optical waveguide according to claim 1, wherein an average thickness of the first cladding layer is larger than an average thickness of the second cladding layer. 5.   5. The bending stiffness A measured by a method defined in JIS K 7106 is 1.01 to 5 when the bending stiffness B measured by the same method is set to 1, 5. The optical waveguide described.   The optical waveguide according to claim 1, wherein the optical waveguide has a portion whose thickness is thinner than an end portion in a longitudinal direction at a position other than the end portion.   The optical waveguide according to claim 6, wherein a thickness of the core layer at the end is thicker than a thickness of the core layer at a portion other than the end.   The sum of the thickness of the first clad layer and the thickness of the second clad layer at the end is equal to the thickness of the first clad layer and the thickness of the second clad layer at a portion other than the end. The optical waveguide according to claim 6, wherein the optical waveguide is thicker than a sum of the optical waveguides. A core layer including an elongated core portion and a side clad portion provided so as to be adjacent to a side surface of the core portion;
A first cladding layer laminated adjacent to one side of the core layer;
A first support layer laminated adjacent to the first cladding layer;
A second cladding layer laminated adjacent to the other surface side of the core layer;
An optical waveguide structure having a second support layer laminated adjacent to the second cladding layer,
The formation condition of the first cladding layer and the formation condition of the second cladding layer, and the formation condition of the first support layer and the formation condition of the second support layer are different,
The bending stiffness when the optical waveguide structure is bent so that the first support layer side is inward is A ′, and the optical waveguide structure is bent so that the second support layer side is inward An optical waveguide structure characterized in that A ′> B ′, where B ′ is a bending stiffness of A ′.   The optical waveguide structure according to claim 9, wherein the formation condition is at least one of a constituent material and an average thickness.   The optical waveguide structure according to claim 9 or 10, wherein the constituent material of the first support layer is a material having a bending elastic modulus larger than that of the constituent material of the second support layer.   The optical waveguide structure according to claim 9, wherein an average thickness of the first support layer is thicker than an average thickness of the second support layer.   The bending stiffness A 'measured by a method defined in JIS K 7106 is 1.01 to 5 when the bending stiffness B' measured by the same method is 1, 13. An optical waveguide structure according to claim 1. A support substrate comprising an electrical wiring pattern;
9. An opto-electric hybrid board comprising: the optical waveguide according to claim 1 laminated on the support board.   An electronic apparatus comprising the opto-electric hybrid board according to claim 14.

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