TWI434087B - Optical-electrical consolidated substrate and electronic apparatus - Google Patents

Description

Photoelectric hybrid substrate and electronic equipment

The present invention relates to an opto-electric hybrid board in which a flexible optical wiring and an electric wiring are combined, and an electronic apparatus using the same.

In recent years, in the high-speed and high-density signal transmission between electronic components or between wiring boards, in the transmission by the electric wiring, interference or attenuation of signals has become an obstacle, and thus high-speed and high-density are limited. . In order to break this limitation, a technique of using light as a connection between electronic components or wiring boards, that is, a so-called optical interconnection, is being studied. Regarding the light transmission path, a polymer optical waveguide has been attracting attention from the viewpoints of easiness of processing, low cost, high degree of freedom of wiring, and high density.

In particular, optical waveguides used in mobile phones and notebook PCs have been studied, and in order to meet space-saving and thin-film requirements, optical hybrid substrates in which optical wirings and electrical wirings are combined have attracted attention (refer to Japanese Patent No. 3193500). Bulletin, Figure 2).

However, in an electronic device such as a mobile phone which is one of the applications of the opto-electric hybrid board, it is assumed that the flexible opto-electric hybrid board is used for signal transmission between the two mechanism parts that can be opened and closed. The substrate spans the connection portion (hinge) of the two mechanism portions. Usually, in order to connect the flexible electric wiring board side to the hinge, the opto-electric hybrid board is bent, and cracks or cracks may occur in the optical waveguide portion due to the bending. In particular, according to the demand for miniaturization of electronic equipment in recent years, the hinge is required to be bent with a small bending radius of R of about 1.5 mm to 2 mm, so that there is a problem that significant cracks or cracks are generated in the hinge.

In view of the above problems, a flexible optical wiring board is proposed in which an optical waveguide film and a flexible electric wiring board are locally joined, and at least a portion where the substrate surface is curved is not joined (refer to Japanese Patent Laid-Open Publication No. 2006). -284925, the scope of application for patents).

However, the present inventors have found that when the optical waveguide film and the flexible electric wiring board are formed to be partially phase-separated, when actually bent by a hinge, particularly in an electronic device, a slide structure is When the optical hybrid substrate is bent in a state where the optical hybrid substrate is bent around the curved portion, and the curved portion moves in accordance with the sliding, the optical waveguide is likely to be laterally offset with respect to the adhesion surface of the flexible electrical wiring board, and In this kind of lateral displacement, the optical waveguide moves while deforming while slipping, and therefore there is a problem that it is easily broken. This tendency is remarkable especially when the opto-electric hybrid board is long. Further, in order to prevent lateral shift of such an optical waveguide, a side guide mechanism may be provided, but it is very complicated and extremely disadvantageous for an electronic device that requires compactness.

In other words, in the opto-electric hybrid board having the separated structure disclosed in Patent Document 2, stress is generated in the final optical waveguide portion, and as a result, the problem of cracking or cracking cannot be solved.

In view of the above, an object of the present invention is to provide an opto-electric hybrid board in which an opto-electric hybrid board is bonded to a flexible electric wiring board, and an electronic device using the opto-electric hybrid board. It does not crack or crack even if it is bent or bent.

The inventors of the present invention have focused on the fact that in the opto-electric hybrid board, the portion where the stress is generated when bent by the hinge greatly affects the electric wiring such as the copper wire constituting the electric wiring board, and concentrates on the core of the optical waveguide. Department (core) part. That is, the modulus of elasticity of the metal material used in the electric wiring is extremely high compared with other materials, and therefore, the stress center is biased toward the electric wiring portion, whereby it is estimated that the stress concentrates on the core of the optical waveguide. The optical waveguide is easily broken. Further, after repeated efforts, it has been found that the core portion of the optical waveguide of the bent portion and the electric wiring of the flexible electric wiring substrate are disposed so as not to overlap each other on the projection surface, whereby the above problem can be solved. The present invention has been completed based on this point of view.

In other words, an opto-electric hybrid board in which an optical waveguide film including a core portion and a clad and a flexible electric wiring substrate are bonded together, and an electronic device including the opto-electric hybrid board, are provided. It is characterized in that the core of the optical waveguide of the curved portion and the electrical wiring of the flexible electric wiring substrate do not overlap on the projection surface.

The opto-electric hybrid board of the present invention and the electronic device using the opto-electric hybrid board have excellent bending durability, and even if the film is repeatedly bent for a long period of time, cracks or cracks do not occur on the opto-electric hybrid board, and good communication can be maintained. Features.

The above described features and advantages of the present invention will be more apparent from the following description.

The opto-electric hybrid board of the present invention is characterized in that the optical waveguide film having the core portion and the cladding layer is bonded to the flexible electric wiring substrate, and the core portion of the optical waveguide of the bent portion and the electric wiring of the flexible electric wiring substrate The wiring does not overlap on the projection surface. In the present invention, as long as the core portion and the electric wiring in the curved portion do not overlap on the projection surface, the portion other than the curved portion, for example, the core portion and the electric wiring in the end portion may overlap on the projection surface, or may not overlapping. However, in terms of the closeness of the electronic device using the opto-electric hybrid board of the present invention, it is necessary to obtain a bonding margin by making the electrical contact of the end portion several times wider than the wiring line, and to form a layer of the core for optical communication. Unlike the layer of the electric wiring, it is preferable that the core portion and the electric wiring overlap on the projection surface at at least one end portion, preferably at both end portions (at least a portion other than the curved portion).

Hereinafter, the details will be described with reference to the drawings.

As shown in FIG. 1, the opto-electric hybrid board 1 of the present invention is formed by bonding an optical waveguide film 2 having a core portion and a cladding layer to a flexible electric wiring substrate 3, and considering the optical waveguide film 2 and the flexible electric wiring substrate. The adhesion of 3 is preferably carried out by the entire surface. Here, the term "bonding" means adhesion or adhesion, and refers to adhesion and adhesion which are not peeled off when the opto-electric hybrid board is bent.

The opto-electric hybrid board of the present invention is suitable for an electronic apparatus having a structure in which a part of the opto-electric hybrid board is movable in the rotational direction about the hinge 4 as shown in FIG. 2, or an electronic apparatus having a sliding structure as shown in FIG. .

Here, the curved portion of the present invention means a portion to be bent or a bent portion in a usual sense, that is, from the starting point of bending to the end point of bending. For example, when the opto-electric hybrid board is bent using a hinge, the bent portion of the present invention refers to a portion that comes into contact with the hinge and an outer edge portion thereof in a state where the opto-electric hybrid board has been bent. More specifically, as shown in FIG. 4, which is an enlarged view of the hinge portion, the curved portion refers not only to the bending starting point X ¹ that starts to bend in contact with the hinge, but also to the bending end point X ² of the bending end, and X. and a portion surrounded ¹ and X ² film side opposite to the optical waveguide portion Y ¹ Y ^2, but also to extend from the portion to the outside by the a, b, c and d are surrounded by section 6. Here, the distance between aX ¹ of the expanded portion is not particularly limited as long as the effect of the present invention is obtained, and is about 1% to 10% of the distance between X ^{1 and} X ² .

Further, in the electronic device having the sliding structure as shown in FIG. 3, even in the case where the hinge is not used, as in the case of the above-described hinge, when the opto-electric hybrid substrate is bent with respect to the bending center, the so-called bending In the state where the opto-electric hybrid board is bent, the shaft 7 corresponding to the hinge 4 (hereinafter referred to as "bending axis") is assumed to be a portion that comes into contact with the bending shaft and an outer edge portion thereof. In the above description of the bent portion, the hinge 4 can be replaced with the bending shaft 7. There are two cases in which the bending axis can be actually formed, and the bending shaft 7 moves in the horizontal direction while rotating, or moves in the horizontal direction without rotating, thereby realizing a sliding structure; there is no bending shaft 7, The opto-electric hybrid board 1 is sandwiched from the up-down direction by a lid or the like, and the end portion X ^{0 of} the opto-electric hybrid board 1 is moved in the horizontal direction by the movement of the lid body, thereby realizing a sliding structure. Moreover, the other end of the opto-electric hybrid substrate may have a configuration that is generally fixed but moved in a direction opposite to the end portion X ⁰ .

The present invention is particularly well applicable to an electronic machine having a sliding configuration as shown in FIG. In other words, in a state in which the opto-electric hybrid board 1 is bent around the curved portion, for example, straight portions of the flexible opto-electric hybrid board located above and below are arranged substantially in parallel. Further, it has a configuration in which at least one end portion X ⁰ of the opto-electric hybrid board 1 is moved in the horizontal direction (the right direction in FIG. 3) while the bending state is maintained, and the bent portion moves with the movement. That is, as the end portion X ⁰ moves, the bending start point moves. In this case, the core of the optical waveguide in the curved portion and the electrical wiring of the flexible electric wiring substrate do not overlap on the projection surface, whereby the effects of the present invention can be exhibited.

In the opto-electric hybrid board 1 of the present invention, as described above, the core portion of the optical waveguide in the bent portion and the electric wiring of the flexible electric wiring substrate do not overlap on the projection surface.

An aspect of the opto-electric hybrid board of the present invention is shown in Figs. 5 and 6. Fig. 5 is a perspective view, and Fig. 6 is a projection view as seen from the direction a of Fig. 5. In the aspect shown in FIG. 5 and FIG. 6 , the electric wiring 31 is disposed on both outer sides of the opto-electric hybrid board 1 , and the core portion 21 is disposed at the center portion, and the two surfaces are not overlapped on the projection surface. Configuration.

Next, Fig. 7 is a projection view showing another aspect of the opto-electric hybrid board of the present invention. The electric wiring 31 has a curved line in both outer directions, and the core portion 21 has a linear shape between both ends. The electric wiring 31 and the core portion 21 are formed so as not to overlap the curved portion and overlap at the end portion.

In addition, FIG. 8 is a projection view further showing another aspect of the opto-electric hybrid board of the present invention. In the drawing, the electric wiring 31 is curved in both outer directions, and the core portion 21 is curved in the inner direction. The electric wiring 31 and the core portion 21 have a form in which the curved portion does not overlap, and a part of the end portion overlaps.

Hereinafter, the optical waveguide film and the flexible electric wiring substrate used in the present invention will be described.

[optical waveguide film]

The optical waveguide film of the present invention is provided with a core portion and a cladding layer, and a material which can be used as an optical waveguide film can be used. For example, a resin film for forming an optical waveguide comprising a resin composition containing (A) a base polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator can be used.

(A) The base polymer is used to secure the strength when forming a cured product such as a film, and is not particularly limited as long as the object can be achieved, and examples thereof include a phenoxy resin, an epoxy resin, and a (meth) group. Acrylic resin, polycarbonate resin, polyarylate resin, polyether decylamine, polyether phthalimide, polyether oxime, or the like, or the like. These base polymers may be used alone or in combination of two or more.

(B) The photopolymerizable compound is not particularly limited as long as it is a compound which is polymerized by irradiation with light such as ultraviolet rays. From the viewpoint of reactivity with light, it is preferred that the compound has an ethylenically unsaturated group in the molecule. compound of. Specific examples thereof include (meth) acrylate, vinylidene halide, vinyl ether, vinyl pyridine, and vinyl phenol. However, from the viewpoint of transparency and heat resistance, (meth) is preferable. )Acrylate. As the (meth) acrylate, any of a monofunctional, bifunctional, and trifunctional (meth) acrylate can be used.

Further, the term "(meth)acrylate" as used herein means acrylate and methacrylate.

The photopolymerization initiator of the component (C) is not particularly limited, and examples thereof include benzophenone and N,N'-tetramethyl-4,4'-diaminobenzophenone (micilenone). ), N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy 4'-dimethylaminobenzophenone, 2-benzyl-2-dimethyl Amino-1-(4-morpholinylphenyl)-butan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl Phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1 An aromatic ketone such as propan-1-one or 1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropan-1-one; 2-ethyl hydrazine, Phenanthrene, 2-tert-butylhydrazine, octamethylguanidine, 1,2-benzopyrene, 2,3-benzopyrene, 2-phenylindole, 2,3-diphenyl Bismuth, 1-chloroindole, 2-methylindole, 1,4-naphthoquinone, 9,10-phenanthrenequinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethylhydrazine Anthraquinones; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether; benzoin compounds such as benzoin, methyl benzoin, ethyl benzoin; benzoin derivatives such as benzyl dimethyl ketal; Chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-bis(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl) A-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4, 2,4,5-triarylimidazole dimer such as 5-diphenylimidazole dimer; bis(2,4,6-trimethylbenzylidene)phenylphosphine oxide, bis(2,6- Phosphine oxides such as dimethoxybenzhydryl)-2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzhydryldiphenylphosphine oxide; 9-benzene Acridine derivatives such as pyridinium, 1,7-bis(9,9'-acridinyl)heptane; N-phenylglycine, N-phenylglycine derivatives, coumarin compounds Wait.

The amount of the (A) base polymer to be blended is preferably from 10% by weight to 80% by weight based on the total amount of the component (A) and the component (B). When the compounding amount is 10% by weight or more, when a film is formed, even a thick film having a film thickness of 50 μm or more can be easily produced. On the other hand, if the compounding amount is 80% by weight or 80%. Below %, the photohardening reaction can be sufficiently carried out. From the above viewpoints, the blending amount of the (A) base polymer is more preferably from 20% by weight to 70% by weight.

The blending amount of the (B) photopolymerizable compound is preferably from 20% by weight to 90% by weight based on the total amount of the component (A) and the component (B). If the compounding amount is 20% by weight or more, the base polymer can be easily entangled and hardened. On the other hand, if the compounding amount is 90% by weight or less, a thick film can be easily formed. From the above viewpoints, the blending amount of the (B) photopolymerizable compound is more preferably from 30% by weight to 80% by weight.

The amount of the (C) photopolymerization initiator is preferably 0.1 parts by mass to 10 parts by mass based on 100 parts by mass of the total of the components (A) and (B). When the amount is 0.1 part by mass or more, the light sensitivity is sufficient. On the other hand, when the amount is 10 parts by mass or less, the surface layer of the photosensitive resin composition is not absorbed during exposure. Will be enhanced, so the internal light hardening is more adequate. Further, the transmission loss is also not increased by the influence of the light absorption of the polymerization initiator itself, and thus is preferable. From the above viewpoints, the compounding amount of the (C) polymerization initiator is more preferably from 0.2 part by mass to 5 parts by mass.

The optical waveguide film of the present invention can be easily produced by dissolving a resin composition containing the components (A) to (C) in a solvent, applying it on a substrate, and removing the solvent. An optical waveguide film is produced. The solvent to be used herein is not particularly limited as long as it can dissolve the resin composition. For example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N can be used. a solvent such as dimethylformamide, N,N-dimethylacetamide or propylene glycol monomethyl ether or a mixed solvent of these. The solid content concentration in the resin solution is usually preferably from about 30% by weight to about 60% by weight.

The thickness of the optical waveguide film in the present invention is not particularly limited, and the thickness after drying is usually 10 μm to 250 μm. When it is 10 μm or more, there is an advantage that the coupling tolerance of the optical waveguide film and the light-receiving element or the optical fiber optics can be amplified, and if it is 250 μm or less, the optical waveguide film and the light-emitting are improved. The advantage of the combined efficiency of components or fibers. From the above viewpoints, the thickness of the film is more preferably in the range of 40 μm to 90 μm.

The substrate used in the production process of the resin film for forming an optical waveguide of the present invention is a support for supporting the film for forming an optical waveguide, and the material thereof is not particularly limited, so that the film for forming an optical waveguide can be easily peeled off in a later step. Further, from the viewpoint of heat resistance and solvent resistance, polyesters such as polyethylene terephthalate, polypropylene, polyethylene, and the like are preferable. The thickness of the substrate is preferably in the range of 5 μm to 50 μm. When the thickness is 5 μm or more, the strength as a support can be easily obtained. When the thickness is 50 μm or less, the gap with the mask becomes small when a pattern is formed (pattefn). And the advantage of forming a finer pattern. From the above viewpoints, the thickness of the substrate is more preferably in the range of 10 μm to 40 μm, particularly preferably 20 μm to 30 μm.

The film for forming an optical waveguide provided on the substrate obtained in the above manner can be easily stored, for example, by being wound into a roll shape. Further, a protective film may be provided on the film for forming an optical waveguide as needed. Further, in order to easily peel off the film for forming an optical waveguide in the subsequent step, the substrate and the protective film may be subjected to an antistatic treatment or the like.

Hereinafter, a method of manufacturing an optical waveguide using the resin film for forming an optical waveguide obtained in the above manner will be described. For example, in the case where the protective film is removed, the protective film is removed, and the lower coating film peeled off from the substrate is laminated while being heated while being heated on the substrate. Here, in terms of adhesion and followability, it is preferred to laminate under reduced pressure. The heating temperature of the resin film is preferably from 50 ° C to 130 ° C, and the pressure of the pressure is preferably from about 0.1 Mpa to about 1.0 Mpa (about 1 kgf/cm ² to about 10 kgf/cm ² ), but is not particularly limited thereto. These conditions.

The thickness of the lower cladding layer is not particularly limited, but is preferably 2 μm to 50 μm. When the thickness of the lower cladding layer is 2 μm or more, the transmitted light can be easily enclosed inside the core. If the thickness of the lower cladding layer is 50 μm or less, the thickness of the entire optical waveguide 1 is not excessively large. In the present invention, the thickness of the lower cladding layer is more preferably in the range of 2 μm to 20 μm, particularly preferably in the range of 5 μm to 15 μm, from the viewpoint of satisfying the bending durability of bending with a small bending radius.

Further, the thickness of the lower cladding layer is a value from the boundary between the core portion and the lower cladding layer to the lower surface of the lower cladding layer.

Next, the lower cladding film is cured by light or heating, and a core film having a higher refractive index than that of the lower cladding film is laminated in the same manner. The active light is irradiated onto the resin film thus laminated in an image-like manner by a negative or positive mask pattern called an artwork. Examples of the light source of the active light include a carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, and a xenon lamp, and the like. Further, a light source for efficiently radiating visible light such as a flood light or a sun light for photography may be used.

The height of the core portion 31 is not particularly limited, but is preferably 10 μm to 150 μm. When the height of the core is 10 μm or more, the alignment tolerance of the core after the formation of the optical waveguide and the light-receiving element or the optical fiber does not become small; if the height of the core is 150 μm or less, the light is light. In the combination of the core after the waveguide is formed and the light-receiving element or the optical fiber, the bonding efficiency does not become small. In the present invention, in particular, from the viewpoint of satisfying the bending durability of bending with a small bending radius, the height of the core portion is more preferably in the range of 30 μm to 120 μm, particularly preferably in the range of 50 μm to 90 μm.

Next, after the exposure, the unexposed portion is removed by wet development, dry development, or the like, and development is performed to produce a core pattern. Here, it is important that the core pattern does not overlap with the electric wiring in the bent portion when it is joined to the flexible electric wiring substrate later.

Regarding development, in the case of wet development, a developer corresponding to the composition of the above resin film such as an organic solvent, an alkaline aqueous solution, or an aqueous developer can be used, and by, for example, spraying, shaking, and brushing (brushing) Development by a known method such as scrapping.

As the developer, a developer which is safe, stable, and has good handleability, such as an organic solvent or an alkaline aqueous solution, is preferably used. Examples of the organic solvent-based developing solution include 1,1,1-trichloroethane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and a ring. Cyclohexanone, methyl isobutyl ketone, γ-butyrolactone, and the like. In order to prevent ignition, water in the range of 1% by weight to 20% by weight may be added to these organic solvents.

As the base of the alkaline aqueous solution, for example, an alkali hydroxide such as a hydroxide of lithium, sodium or potassium, a carbonate such as lithium, sodium, potassium or ammonium carbonate or a bicarbonate, a potassium phosphate, a sodium phosphate or the like can be used. Alkali metal phosphate, alkali metal pyrophosphate such as sodium pyrophosphate or potassium pyrophosphate. Further, the alkaline aqueous solution for development is preferably, for example, a thin solution of 0.1% by weight to 5% by weight of sodium carbonate, a thin solution of 0.1% by weight to 5% by weight of potassium carbonate, and 0.1% by weight to 5% by weight of sodium hydroxide. a thin solution, a thin solution of 0.1 wt% to 5 wt% sodium tetraborate, and the like. Further, the pH of the alkaline aqueous solution used for development is preferably in the range of 9 to 14, and the temperature thereof can be adjusted in accordance with the developability of the photosensitive resin composition layer. Further, a surfactant, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like may be added to the alkaline aqueous solution.

The aqueous developing solution is composed of one or more organic solvents, such as water or an aqueous alkali solution. Here, in addition to the above substances, the alkali substance may, for example, be borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine or 2-amino-2-hydroxymethyl- 1,3-propanediol, 1,3-diaminopropanol-2, morpholine, and the like. The pH of the developer is preferably set to a value as small as possible within a range in which the photoresist can be sufficiently developed. Preferably, the pH is set to 8 to 12, and more preferably, the pH is set to 9 to 10. Examples of the organic solvent include triacetone alcohol, acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethanol, isopropanol, butanol, and diethylene glycol monomethyl. Ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and the like. These organic solvents may be used singly or in combination of two or more kinds. Usually, the concentration of the organic solvent is preferably from 2% by weight to 90% by weight, and the temperature thereof can be adjusted according to developability. Further, a small amount of a surfactant, an antifoaming agent, or the like may be added to the aqueous developing solution.

Further, two or more development methods may be used in combination as needed. Examples of the development method include a spray method such as a dip method, a stirring method, and a high-pressure spray method, brushing, and slapping.

As a treatment after the development, heating optionally about 60 ℃ ~ 250 ℃ or 0.1mJ / cm ² ~ 1000mJ exposure of about ² / cm, whereby the core portion further harden the pattern used.

Next, an optical waveguide was produced by laminating an upper cladding film having a lower refractive index than that of the core film in the same manner. The thickness of the upper cladding layer is not particularly limited as long as it can be embedded in the core portion, and the thickness after drying is preferably 2 μm to 50 μm, and the bending durability against bending with a small bending radius is satisfied. The thickness thereof is more preferably in the range of 2 μm to 20 μm, particularly preferably in the range of 5 μm to 15 μm. The thickness of the upper cladding layer may be the same as or different from the thickness of the lower cladding layer initially formed. Further, the thickness of the upper cladding layer shown here is a value from the boundary between the core portion and the upper cladding layer to the upper surface of the upper cladding layer.

[Flexible Electrical Wiring Substrate]

As the flexible electric wiring substrate, an FPC (Flexible Printed Circuit) substrate can be preferably used. The substrate material of the FPC substrate can be: polyimine, polyamine, polyetherimide, polyethylene terephthalate, liquid crystal polymer, etc., but generally, from the viewpoint of heat resistance or easy availability, Polyimine is used. As a commercial item, the FPC board|substrate which used Kapton (made by Toray-Dupont Co., Ltd.) is mentioned, for example.

Here, the thickness of the substrate constituting the flexible electric wiring substrate is not particularly limited, and the thickness of the substrate can be appropriately determined depending on the thickness required for the opto-electric hybrid board itself. Specifically, it is preferably in the range of 5 μm to 50 μm. .

In addition, when the electric wiring in the flexible electric wiring board is joined to the optical waveguide, it is important to perform wiring so as not to overlap the core portion in the curved portion.

[Optical hybrid substrate]

The optical waveguide film and the flexible electric wiring substrate are joined to each other to manufacture the opto-electric hybrid board of the present invention.

When the optical waveguide film is bonded to the flexible electric wiring substrate, an adhesive may be used as needed. The type of the adhesive can be appropriately determined depending on the material of the optical waveguide film and the flexible electric wiring substrate.

In order to make the opto-electric hybrid substrate flexible, it is preferred that the adhesive has flexibility after curing. Specifically, the elastic modulus after hardening is preferably 700 MPa or less, more preferably 600 MPa or less. Particularly good is 500Mpa or less. Further, from the viewpoint of the strength of the adhesive, it is preferably 1 Mpa or more, more preferably 5 Mpa or more.

For the type of the adhesive, the acrylic rubber-based adhesive or the commercially available product is preferably a high heat-resistant adhesive insulating material KS7003 (elastic modulus 700 MPa) manufactured by Hitachi Chemical Co., Ltd., and Hitachi Chemical Co., Ltd. Polymer (Hitachi Kasei Polymer) Co., Ltd., an adhesive for Hi-Bon 808 (elastic modulus 50 MPa) or the like for a flexible printed wiring board.

The method of bonding the optical waveguide film to the flexible electric wiring substrate is not particularly limited, and from the viewpoint of adhesion and prevention of bubble entrapment, it is preferable to use a roll laminator or a flat type lamination. Machine method. The lamination temperature at the time of using a roll laminator is preferably in the range of room temperature (25 ° C) to 100 ° C. When the laminating temperature is room temperature (25 ° C) or more, the adhesion between the flexible electric wiring substrate and the optical waveguide is improved; if the lamination temperature is 100 ° C or less, the adhesive layer is not Flow to obtain the desired film thickness. From the above viewpoints, it is more preferably in the range of 40 ° C to 100 ° C. The pressure is preferably 0.2 MPa to 1.0 MPa (1 kgf/cm ² to 10 kgf/cm ² ), and the lamination speed is preferably 0.1 m/min to 3 m/min, but is not particularly limited to these conditions.

In addition, the flat type laminating machine is a laminating machine in which a laminated material is sandwiched between a pair of flat plates, and the flat plate is pressed to be pressed, and it is preferable to use, for example, a vacuum press fit. machine. The heating temperature here is preferably from 50 ° C to 100 ° C, and the pressure is preferably from 0.1 MPa to 1.0 MPa (1 kgf / cm ² to 10 kgf / cm ² ), but is not particularly limited thereto. condition.

Example

Hereinafter, the embodiments of the present invention will be more specifically described, but the present invention is not limited by these examples.

(evaluation method)

1. Tensile modulus and tensile strength

A sample having a width of 10 mm and a length of 70 mm was obtained from the film to be measured, and the measurement was carried out under the following conditions using a tensile tester ("RTM-100" manufactured by Orientec Co., Ltd.) in accordance with JIS-K7127.

Condition: The distance between the chucks is 50 mm, the temperature is 25 ° C, and the stretching speed is 50 mm/min.

The tensile elastic modulus is calculated from the first straight line portion using the tensile stress-strain curve according to the following formula. Further, in the tensile stress-strain curve, the maximum strength up to the fracture was taken as the tensile strength.

Tensile modulus of elasticity (MPa) = difference in stress between two points on a straight line (N) The original average cross-sectional area of the optical waveguide film (mm ² ) ÷ the difference between the two points

2. Bending endurance test

The optical hybrid substrate manufactured in each of the examples and the comparative examples was subjected to a bending endurance test using a bending endurance tester in the form of sliding the opto-electric hybrid substrate as shown in FIG. The test was carried out in the case where the optical hybrid substrate obtained in each of the examples and the comparative examples was placed on the inner side with respect to the bending axis 7 . Further, the bending radius was also tested under the conditions of 1.5 mm and 1.0 mm, and the test was carried out under the conditions of a sliding speed of 80 mm/sec and a distance between X ¹ and X ² of 20 mm. As for the evaluation, in Example 1, Comparative Example 1, and Reference Example 1, the presence or absence of the fracture was observed every 10,000 times, and the maximum number of unbroken times was determined. For Comparative Example 2, the presence or absence of the fracture was observed every 1000 times. The maximum number of times that it has not been broken.

Example 1

(1-1) Fabrication of optical waveguide film

[Production of Resin Film for Cladding Formation]

48 parts by mass of a phenoxy resin (trade name: PHENO TOHTO YP-70, manufactured by Tohto Kasei Co., Ltd.) as a (A) binder polymer, and 49.6 parts by mass of (B) photopolymerization were weighed. An alicyclic diepoxy carboxylic acid ester of a compound (trade name: KRM-2110, molecular weight: 252, manufactured by Asahi Kasei Kogyo Co., Ltd.), and 2 parts by mass of triphenyl as (C) photopolymerization initiator Based on hexafluoroantimonate (trade name: SP-170, manufactured by Asahi Kasei Kogyo Co., Ltd.), 0.4 parts by mass of SP-100 (trade name, manufactured by Asahi Kagaku Kogyo Co., Ltd.) as a sensitizer, 40 A mass part of propylene glycol monomethyl ether acetate as an organic solvent was placed in a wide-mouth polyethylene bottle, using a mechanical stirrer, a shaft, and a propeller at a temperature of 25 ° C. The mixture was stirred at a number of 400 rpm for 6 hours to prepare a resin varnish A for cladding formation. Then, a polyflon filter (trade name: PF020, manufactured by Advantec Toyo Co., Ltd.) having a pore size of 2 μm was used, and the mixture was filtered under pressure at a temperature of 25 ° C and a pressure of 0.4 MPa, and further used. A vacuum pump and a bell jar were degassed under reduced pressure for 15 minutes under a reduced pressure of 50 mmHg.

The resin varnish A for cladding formation obtained above was applied to a polyimide film using a coater (Multi-Coater TM-MC, manufactured by HIRANO TECSEED Co., Ltd.) (trade name: Mictron, Toray Co., Ltd.) , corona-treated surface of thickness: 12 μm), dried at 80 ° C for 10 minutes, and then dried at 100 ° C for 10 minutes, and then attached as a protective film of a release PET film (trade name: Purex A31, Teijin DuPont The film (Teijin Dupont Films Co., Ltd., thickness: 25 μm) was used to form the release side as the resin side, and a resin film for cladding formation was obtained. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coater. In the present embodiment, the film thickness after hardening is adjusted to 20 μm for the lower cladding layer and 70 μm for the upper cladding layer.

[Production of Resin Film for Core Layer Formation]

26 parts by mass of a phenoxy resin (trade name: PHENO TOHTO YP-70, manufactured by Tohto Kasei Co., Ltd.) as the (A) binder polymer, and 36 parts by mass of the (B) photopolymerizable compound were used. 9-bis[4-(2-acryloxyethoxy)phenyl]anthracene (trade name: A-BPEF, manufactured by Shin-Nakamura Chemical Co., Ltd.), and 36 parts by mass of bisphenol A type acrylic ring Oxygen ester (trade name: EA-1020, manufactured by Shin-Nakamura Chemical Co., Ltd.), and 1 part by mass of bis(2,4,6-trimethylbenzylidene) as (C) photopolymerization initiator Phenylphosphine oxide (trade name: Irgacure 819, manufactured by Ciba Specialty Chemicals Co., Ltd.), and 1 part by mass of 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy- 2-methyl-1-propan-1-one (trade name: Irgacure 2959, manufactured by Ciba Specialty Chemicals Co., Ltd.), 40 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent, in addition to the above The resin varnish B for core layer formation was blended in the same method and conditions as in the production example. Then, pressure filtration was carried out in the same manner and under the same conditions as in the above production examples, and further defoaming under reduced pressure.

In the same manner as in the above-described production example, the resin layer varnish B for core layer formation obtained above was applied to a non-treated surface of a PET film (trade name: COSMOSHINEA 1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm). After drying, a release PET film (trade name: Purex A31, Teijin DuPont Film Co., Ltd., thickness: 25 μm) as a protective film was attached, and the release surface was made into a resin side, and a resin film for forming a core layer was obtained. In the present embodiment, the gap of the coater was adjusted so that the film thickness after hardening was 50 μm.

[Production of Optical Waveguide Film]

The release PET film (Purex A31) which is a protective film of the resin film for forming a lower cladding layer obtained above was peeled off, and the relative side of the base film was used by using an ultraviolet exposure machine (manufactured by OAK Co., Ltd., EXM-1172). The side was irradiated with 1 J/cm ² of ultraviolet rays (wavelength: 365 nm), followed by heat treatment at 80 ° C for 10 minutes, thereby forming a lower cladding layer.

Then, using a roll laminator (manufactured by Hitachi Kasei Techno Plant Co., Ltd., HLM-1500), the core layer was placed under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C, and a lamination speed of 0.2 m/min. The resin film for forming is laminated on the lower cladding layer, and then vacuum-treated into 500 Pa or by using a vacuum pressure type laminator (manufactured by Nago Seisakusho Co., Ltd., MVLP-500) as a flat type laminator. After 500 Pa or less, the core layer was formed by heating and pressure bonding under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C, and a press time of 30 seconds.

Next, a negative-type photomask having a width of 50 μm was used, and ultraviolet rays (wavelength: 365 nm) of 0.6 J/cm ² were irradiated by the above-mentioned ultraviolet exposure machine, followed by exposure at 80° C. for 5 minutes, followed by heating to form a core portion as shown in the figure. The shape shown in 7.

Then, the PET film which is a support film was peeled off, and the core pattern was developed using a developing solution (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio). Next, it was washed with a washing liquid (isopropyl alcohol), and dried by heating at 100 ° C for 10 minutes.

Next, the above-mentioned resin film for forming a cladding layer was laminated as the upper cladding layer under the same lamination conditions as described above. Further, after irradiating ultraviolet rays (wavelength: 365 nm) having a total of 25 J/cm ² on both surfaces, heat treatment was performed at 160 ° C for 1 hour to prepare a flexible optical waveguide in which an upper cladding layer was formed and a base film was disposed outside. . Further, in order to remove the polyimide film, the flexible optical waveguide was treated under high temperature and high humidity conditions of 85 ° C / 85% for 24 hours to prepare a flexible optical waveguide from which the base film was removed.

Further, the refractive index of the core layer and the cladding layer was measured using a prism coupler (Model 2010) manufactured by Metricon Co., Ltd., and it was found that the core layer was 1.584 and the cladding layer was 1.550 at a wavelength of 830 nm. In addition, the light source is a 850 nm surface-emitting laser ((EXFO-made, FLS-300-01-VCL), and the light-receiving sensor is Q82214 manufactured by Advantest Co., Ltd. by a cutback method ( Measuring waveguide lengths 10 cm, 5 cm, 3 cm, 2 cm, incident optical fiber: GI-50/125 multimode fiber (NA = 0.20), outgoing fiber: SI-114/125 (NA = 0.22)), measuring the fabricated optical waveguide The transmission loss was 0.05 dB/cm.

Moreover, the tensile elastic modulus and tensile strength of the obtained optical waveguide film were measured by the above-mentioned method, and as a result, it was found that the tensile elastic modulus was 2,000 MPa and the tensile strength was 70 MPa.

(1-2) Production of sheet adhesive

100 parts by mass of HTR-860P-3 (manufactured by Imperial Chemical Industry Co., Ltd., trade name, glycidyl group-containing acrylic rubber, molecular weight of 1,000,000, Tg-7 ° C), and 5.4 parts by mass of YDCN-703 (East Capital) YCCN-8170C, manufactured by Toei Chemical Co., Ltd. , epoxy equivalent 157), 15.3 parts by mass of PLYOPHEN LF2882 (manufactured by Dainippon Ink and Chemicals Co., Ltd., trade name, bisphenol A novolak resin), 0.1 parts by mass of NUCA-189 (Nippon) Manufactured by Unicar Co., Ltd., trade name, γ-mercaptopropyltrimethoxydecane, 0.3 parts by mass of NUCA-1160 (manufactured by Nippon Unicar Co., Ltd., trade name, γ-ureidopropyl triethoxy decane), 30 parts by mass of A-DPII (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name, dipentaerythritol hexaacrylate), 1.5 parts by mass of Irgacure 369 (manufactured by Ciba Specialty Chemicals Co., Ltd., trade name, 2-benzyl-2) -dimethylamino 1-(4-morpholinylphenyl)-butanone-1-one: I-369), cyclohexanone, stirred and mixed, and vacuum degassed. The adhesive varnish was applied to a surface release-treated polyethylene terephthalate (manufactured by Teijin Tetoron Film: A-31) having a thickness of 75 μm, and heated at 80 ° C for 30 minutes. Dry to obtain a sticky sheet. A light-transmitting support substrate having a thickness of 80 μm is laminated on the adhesive sheet (manufactured by THERMO Co., Ltd., low-density polyethylene terephthalate/vinyl acetate/low-density polyethylene terephthalate III) A film: FHF-100), thereby producing a sheet-like adhesive including a protective film (surface release-treated polyethylene terephthalate), an adhesive layer, and a light-transmitting support substrate. The thickness of the adhesive layer was 10 μm.

The adhesive layer of the sheet-like adhesive thus prepared was cured at 160 ° C for 1 hour, and the transmittance was measured using a U-3310 ultraviolet-visible spectrophotometer manufactured by Hitachi High-Technologies Co., Ltd., and it was found that the wavelength was With a high transmittance of 98% or more at 850 nm, the transmission loss is equivalent to 0.1 dB or less.

Further, the refractive index was measured by a 稜鏡 coupler (Model 2010) manufactured by Metricon, and it was found that the refractive index was 1.505 at a wavelength of 830 nm.

Moreover, the tensile elastic modulus of the obtained sheet-like adhesive was measured by the above method, and it was found that the tensile elastic modulus was 350 MPa.

(1-3) Production of Photoelectric Mixed Substrate

Using a roll laminator (manufactured by Hitachi Kasei Techno Plant Co., Ltd., HLM-1500), the protective film was peeled off under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C, and a lamination speed of 0.2 m/min. The adhesive is laminated to the flexible optical waveguide. Then, using a dicing saw (manufactured by DISCO Co., Ltd., DAD-341), the waveguide was processed into a strip shape (length: 120 mm., width: 2 mm), and the substrate side was irradiated with 250 mJ/cm ² . Ultraviolet rays (365 nm) reduce the adhesion of the adhesive layer to the interface of the support substrate and peel off the support substrate to obtain an optical waveguide with an adhesive.

Next, a mask alignment exposure mechanism attached to the ultraviolet exposure machine (DAINIPPON SCREEN Co., Ltd., MAP-1200-L) is used to position the optical waveguide with the adhesive layer on the flexible electric wiring substrate having the electric wiring. (The roll bonding machine is used at a specific portion of a length of 120 mm, a width of 2 mm, a substrate: Kapton 100EN (tensile strength measured by the above method: 370 MPa), substrate thickness: 25 μm, copper circuit thickness: 12 μm) After temporary pressure bonding under the conditions of a pressure of 0.4 MPa, a temperature of 80 ° C, and a lamination speed of 0.2 m/min, the film was heated at 160 ° C for 1 hour in a clean oven (C1ean Oven) to form a flexible optical waveguide and an electric wiring substrate. Next, an opto-electric hybrid substrate as shown in FIG. 7 as a projection image is obtained.

Here, the light transmittance of KaptonEN, which is a substrate of a flexible electric wiring board, was measured by a U-3310 spectrophotometer manufactured by Hitachi High-Technologies Co., Ltd., and it was found that the light transmittance was 86% at a wavelength of 850 nm. . The transmission loss is equivalent to 0.7 dB, and even if the adhesion layer is integrated, the light loss when passing through the electric wiring board is low loss of less than 1 dB. Therefore, in the present embodiment, the through hole for light transmission is not provided. (through hole) structure. The results of evaluation by the above method are shown in Table 1.

Comparative example 1

In the first embodiment, the core portion 21 and the electric wiring 31 are linear, and the optical hybrid substrate is obtained in the same manner as in the first embodiment except that the core portion 21 and the electric wiring 31 in the curved portion are overlapped on the projection surface. .

Comparative example 2

In the first comparative example, the sheet-like adhesive was laminated on the same end of the flexible optical waveguide as in the first embodiment, and the laminate was not bonded to the central portion, except that it was produced in the same manner as in Comparative Example 1. Photoelectric hybrid substrate. Evaluation was carried out in the same manner as in Example 1, and the results are shown in Table 1.

Reference example 1

Using the optical waveguide unit produced in Example 1, the bending endurance test was conducted in the same manner as the opto-electric hybrid substrate of Example 1. The results are shown in Table 1.

As shown in the first table, the core portion of the optical waveguide in the curved portion and the electrical wiring of the flexible electric wiring substrate do not overlap on the projection surface, so that the bending durability of the opto-electric hybrid board can be dramatically improved.

[Industrial availability]

The opto-electric hybrid board of the present invention has extremely excellent bending durability, and cracks or cracks do not occur in the optical waveguide film portion even if it is repeatedly bent for a long period of time. Therefore, the opto-electric hybrid board of the present invention can be applied to an electronic device such as a mobile phone, and the hinge portion can maintain a good communication function for a long period of time even when it is required to bend with a small bending radius of R of about 1.5 mm to 2 mm. And the electronic machine itself can achieve high reliability and durability.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

1. . . Photoelectric hybrid substrate

2. . . Optical waveguide film

3. . . Flexible electrical wiring substrate

4. . . Hinge

6. . . Bending

7. . . Bending axis

twenty one. . . Core

31. . . Electric wiring

Fig. 1 is a conceptual diagram showing an opto-electric hybrid board.

2 is a conceptual view showing a state in which an opto-electric hybrid board is bent.

3 is a conceptual view showing an example of an opto-electric hybrid board when the electronic device has a sliding structure.

Figure 4 is an enlarged view of the hinge portion of Figure 2.

Fig. 5 is a perspective view showing an example of an opto-electric hybrid board of the present invention.

Fig. 6 is a projection view of the opto-electric hybrid board of the present invention shown in Fig. 5 as seen from the direction a.

Fig. 7 is a projection view showing another example of the opto-electric hybrid board of the present invention.

Fig. 8 is a projection view showing another example of the opto-electric hybrid board of the present invention.

1. . . Photoelectric hybrid substrate

2. . . Optical waveguide film

3. . . Flexible electrical wiring substrate

4. . . Hinge

Claims (4)

An opto-electric hybrid board obtained by bonding an optical waveguide film having a core portion and a cladding layer to a flexible electric wiring board, and a core portion of the optical waveguide and a flexible electric wiring substrate of the bent portion of the opto-electric hybrid board The electric wiring does not overlap on the projection surface, and the projection surface is a projection surface projected from a normal direction of the opto-electric hybrid board, and the optical waveguide film and the flexible electric wiring substrate are joined by the entire surface. The opto-electric hybrid board according to claim 1, wherein at least a part of the optical waveguide and the electric wiring of the flexible electric wiring board overlap the projection surface in at least a part other than the curved portion. An electronic device having an opto-electric hybrid substrate according to claim 1 or 2, and a hinge for bending the opto-electric hybrid substrate, wherein the electronic device has a part of the opto-electric hybrid substrate to the hinge A structure that is movable in the direction of rotation. An electronic device comprising: an opto-electric hybrid substrate according to claim 1 or 2, wherein the opto-electric hybrid substrate maintains a state of being bent around a bent portion, and the opto-electric hybrid At least one end of the substrate moves in a horizontal direction, and the bent portion moves with the movement.