JP2012103425A - Manufacturing method for photoelectric composite wiring board, and photoelectric composite wiring board manufactured by the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a photoelectric composite wiring board which can realize a composite of an optical waveguide and an electric circuit with high adhesion, thereby enabling a manufacture of the photoelectric composite wiring board with no loss in the optical waveguide or no coupling loss between a light reception element and an optical circuit.SOLUTION: A manufacturing method for a photoelectric composite wiring board 18 comprises: an optical waveguide formation step of forming a clad having a core 14 embedded on a substrate 16; a metal layer lamination step of laminating an uncured resin composition 12 where a metal base 11 having at least one surface thereof roughened is laminated on a side of the substrate 16 opposite to the optical waveguide; a metal layer formation step of forming a metal layer by curing the uncured resin composition 12; and an electric circuit formation step of forming an electric circuit 11a on the metal base 11. The surface roughness Rz of the metal base is preferably 0.5 μm or more and 5 μm or less. The refractive index of the uncured resin composition is preferably lower than or equal to that of the core.

Description

  The present invention relates to a method for manufacturing a photoelectric composite wiring board, and a photoelectric composite wiring board manufactured by the manufacturing method.

  Conventionally, an optical fiber has been mainly used as a transmission medium in FTTH (Fiber To The Home) and long-distance and medium-distance communication in the in-vehicle field. However, in recent years, high-speed transmission using an optical medium has become necessary even at a short distance within 1 m. In this high-speed transmission over a short distance, high-density wiring (narrow pitch, branching, crossing, multilayering, etc.), surface mountability, integration with an electric substrate, and bending with a small diameter are possible instead of the optical fiber. Therefore, an optical waveguide type optical wiring board is suitable.

  To make the optical wiring board, two types of replacement are necessary. One is the replacement of the printed wiring board (PWB) used for the printed wiring board, and the other is the replacement of the flexible printed circuit (FPC) used for the hinge of the small terminal device. is there. In either type, it is indispensable to transmit electrical wiring and low-speed signals for operating a VCSEL (Vertical Cavity Surface Emitting Laser), PD (Photo Diode), or IC, which is a light emitting / receiving element. The form of the photoelectric composite wiring board in which the electric circuit is mixed is ideal.

  As a method of combining the optical waveguide and the electric circuit in order to obtain the form of the photoelectric composite wiring board as described above, for example, there is a method of directly forming a metal layer on the optical waveguide. In order to form the metal layer directly on the optical waveguide, it is necessary to form irregularities on the material by chemical treatment so that the anchor effect can be obtained. However, since normal materials have transparency, the structure is uniform, and even if this material is subjected to permanganic acid treatment, which is a pretreatment for plating, the etching rate is equal and the overall thickness is uniform. Unevenness is difficult to obtain just by reducing.

  Therefore, it is possible to add non-uniformity to the material by blending materials that are easily or chemically difficult to process than the base materials. Often becomes opaque. For this reason, in applications where extreme transparency is required, it is currently impossible to make a material that can achieve both transparency and adhesion. In addition, when an opaque material having a plating property is bonded, there also arises a problem that light cannot be coupled between the light emitting element or the light receiving element mounted on the electric circuit and the optical waveguide.

  As another method of combining the optical waveguide and the electric circuit, there is a method of attaching a printed wiring board on the optical waveguide via an adhesive layer (see, for example, Patent Document 1). However, in such a method, since the optical circuit and the electric circuit are separately manufactured and then pasted, the positional accuracy of the electric circuit and the waveguide is deteriorated. As a result, it is impossible to mount the light emitting / receiving element reliably, and the yield of the light receiving / emitting element may be deteriorated.

  Moreover, since the printed wiring board is usually opaque, it is necessary to open it in advance before pasting. However, since the adhesive layer wraps around the opening and irregularities are generated on the surface of the printed wiring board, the coupling efficiency may be reduced. Furthermore, since the printed wiring board has a relatively thick structure, the distance between the light emitting / receiving element and the waveguide is increased by the thickness and the adhesive layer, and the coupling loss may be increased.

  Further, as a method of combining the optical waveguide and the electric circuit, there is a method in which a core and a clad are sequentially formed on a copper foil with a clad resin and attached to a substrate (for example, see Patent Documents 2 and 3). However, in such a method, since the core is formed by photolithography, UV light passes through the clad and is irregularly reflected by the copper foil having irregularities, so that the core side wall is roughened, and the waveguide loss is reduced. It may get worse. In addition, there may be a problem that it is difficult to align the positions of the optical waveguide and the electric circuit.

JP 2003-344684 A JP-A-2005-300930 JP 2006-39231 A

  The present invention has been made in view of the above-described problems of the prior art, and the object thereof is to make it possible to combine an optical waveguide and an electric circuit with high adhesion, and to reduce the coupling loss between the light emitting / receiving element and the optical circuit and the loss of the optical waveguide. -It aims at providing the manufacturing method of an electrical composite wiring board.

  In the method for manufacturing an opto-electric composite wiring board according to the present invention, an optical waveguide forming step of forming a clad with a core embedded on a substrate, and at least one surface of the optical waveguide is roughened on the opposite side of the substrate. A metal layer laminating step of laminating an uncured resin composition, a metal layer forming step of curing the uncured resin composition to form a metal layer, and the metal substrate And an electric circuit forming step for forming an electric circuit thereon.

  According to such a configuration, since the uncured resin is laminated on the metal base whose surface is roughened, the resin is sufficiently filled in the uneven portions of the metal surface, and the resin after being cured. And metal can be more closely attached. In addition, a metal layer containing an uncured resin composition, in which a metal base material having a roughened surface at least on one side is laminated on an optical waveguide having a core and a clad layer surrounding the core, Furthermore, since the uncured resin composition is cured, it is possible to simultaneously form the optical waveguide and the metal film. Further, the metal film can be formed without increasing the number of optical waveguide forming steps. Furthermore, since the laminating method is used when laminating the uncured resin, build-up is possible, so that productivity is also excellent.

  The surface roughness Rz of the metal substrate is preferably 0.5 μm or more and 5 μm or less.

  Moreover, it is preferable that the refractive index of the uncured resin composition is the same as or lower than the refractive index of the core.

  The resin composition is preferably a dry film.

  The photoelectric composite wiring board according to the present invention is obtained by the method for manufacturing an optical composite wiring board.

  According to the present invention, it is possible to provide a method of manufacturing an optical / electrical composite wiring board that can combine an optical waveguide and an electric circuit with high adhesion, and does not have a coupling loss between a light emitting / receiving element and an optical circuit or an optical waveguide. it can.

It is the schematic for demonstrating the manufacturing method of the photoelectric composite wiring board which concerns on this invention.

  Hereinafter, although the embodiment concerning the present invention is described, the present invention is not limited to these.

  In the method for manufacturing an opto-electric composite wiring board according to the present invention, an optical waveguide forming step of forming a clad with a core embedded on a substrate, and at least one surface of the optical waveguide is roughened on the opposite side of the substrate. A metal layer laminating step of laminating an uncured resin composition, a metal layer forming step of curing the uncured resin composition to form a metal layer, and the metal substrate And an electric circuit forming step for forming an electric circuit thereon.

  FIG. 1 is a schematic cross-sectional view for explaining a method for manufacturing a metal-clad laminate and a photoelectric composite wiring board according to this embodiment. In FIG. 1, reference numeral 10 is a mirror surface, reference numeral 11 is a metal substrate, reference numeral 11a is an electric circuit, reference numeral 12 is an uncured resin composition, reference numeral 13 is a cured resin composition, reference numeral 14 is a core, reference numeral 15 is a cladding layer. Reference numeral 15a denotes an upper clad layer, reference numeral 15b denotes a lower clad layer, reference numeral 16 denotes a substrate, reference numeral 17 denotes an optical waveguide, and reference numeral 18 denotes a photoelectric composite wiring board.

<Optical waveguide formation process>
An optical waveguide 17 as shown in FIG. The optical waveguide 17 propagates by totally reflecting the guided light input to the mirror surface 10 at one end at the interface between the core 14 and the second cladding layer 12 having different refractive indexes, and outputs the light from the mirror surface 10 at the other end. This optical waveguide 17 provides an optical circuit.

  First, the core portion 14 is formed inside the clad layer 15 of the substrate 16 provided with the clad layer 15.

  Specifically, first, as shown in FIG. 1A, the clad upper layer 15a is formed on the surface of the temporary substrate 16 '.

  As the substrate 16 ′, various organic substrates and inorganic substrates are used without particular limitation. Specific examples of the organic substrate include an epoxy substrate, an acrylic substrate, a polycarbonate substrate, and a polyimide substrate. Examples of the inorganic substrate include a silicon substrate and a glass substrate. Further, it may be a printed circuit board in which a circuit is previously formed on the board.

  As a method of forming the clad upper layer 15a, after bonding a resin film made of a curable resin material having a predetermined refractive index for forming the clad upper layer 15a on the surface of the temporary substrate 16 ′, A method of curing, a liquid curable resin material for forming the clad upper layer 15a is applied, and then a method of curing or a varnish of a curable resin material for forming the clad upper layer 15a is applied. Thereafter, a curing method and the like can be mentioned. When forming the clad upper layer 15a, it is preferable to perform plasma treatment or the like on the surface of the temporary substrate 16 'in advance in order to improve adhesion.

  As a specific method of forming the clad upper layer 15a, for example, a method of bonding a resin film to form the clad upper layer 15a and then curing, or a method for forming the clad upper layer 15a. For example, a liquid curable resin material or a curable resin material varnish is applied and then cured.

  For example, the following method is used as a specific method of curing after laminating the resin film to form the clad upper layer 15a. First, after placing the resin film made of curable resin on the surface of the substrate 16 so as to overlap, the resin film made of curable resin is bonded to the surface of the substrate 16 by a heat press, or a transparent adhesive. Paste together. And it hardens | cures by irradiating light to the bonded resin film, or heating.

  In addition, as a specific method of curing after applying a liquid curable resin material or a varnish of the curable resin material for forming the clad upper layer 15a, for example, the following method may be used. Used. First, a liquid curable resin material or a varnish of a curable resin material is applied to the surface of the temporary substrate 16 'using a spin coating method, a bar coating method, a dip coating method, or the like. Then, the applied liquid curable resin material or varnish of the curable resin material is cured by irradiating light or heating.

  As the curable resin material for forming the clad upper layer 15a, a material whose refractive index at the transmission wavelength of guided light is lower than that of the material of the core part 14 to be formed later is used. Examples of the refractive index at the transmission wavelength include those of about 1.5 to 1.55. Examples of such curable resin materials include epoxy resins, acrylic resins, polycarbonate resins, polyimide resins, and the like having the above-described refractive index.

  Next, a core made of a photosensitive material is formed on the outer surface of the formed clad upper layer 15a.

  Here, the photosensitive material is a material in which the solubility of a portion irradiated with energy rays with respect to a liquid used in development described later changes. Specifically, for example, a material that is difficult to dissolve in a liquid used in development described later before irradiation with energy rays, but is easily dissolved after irradiation with energy rays can be used. As another example, there is a material that easily dissolves in a liquid used in development described later before irradiation with energy rays, but is difficult to dissolve after irradiation with energy rays. Specific examples of the photosensitive material include a photosensitive polymer material.

  The energy beam is not particularly limited as long as the solubility can be changed. Specifically, ultraviolet rays are preferably used from the viewpoint of ease of handling. As the photosensitive material, generally, a photosensitive polymer material whose solubility changes in a portion irradiated with ultraviolet rays is preferably used. More specifically, a photosensitive polymer material that is hard to dissolve in a liquid used in development described later is preferably used by curing the portion irradiated with ultraviolet rays.

  As a method of forming the core material layer, a resin film (photosensitive film) made of a photosensitive polymer material having a predetermined refractive index for forming the core material layer is formed on the outer surface of the clad upper layer 15a. A method of bonding, a method of applying a liquid photosensitive polymer material for forming the core material layer, a photosensitive polymer material varnish for forming the core material layer 14, and then drying And the like. In addition, when the core material layer is formed, it is preferable to perform a plasma treatment or the like in advance in order to activate the outer surface of the clad upper layer 15a and improve the adhesion.

  The resin film (photosensitive film) made of the photosensitive polymer material is preferably a dry film obtained by applying a semi-cured photosensitive polymer material to a polyethylene terephthalate (PET) film or the like. By using a dry film, the handleability is improved, and entrainment of bubbles can be prevented when laminating the core. Such a dry film is usually protected by a protective film.

  As the photosensitive polymer material for forming the core material layer, a material having a higher refractive index at the transmission wavelength of the guided light than the material of the first cladding upper layer 15a is used. Examples of the refractive index at the transmission wavelength include about 1.55 to 1.6.

  As a kind of the photosensitive polymer material for forming the core material layer, a photosensitive resin having an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, or the like having a refractive index as described above as a resin component. Materials. Among these, bisphenol type epoxy resin is particularly preferable, and as the photosensitive polymer material for forming the core material layer, a resin composition containing a bisphenol type epoxy resin and a photocationic curing agent has a heat resistance. Since a high waveguide can be obtained, it is preferable because it can be combined with a printed circuit board or the like. From the viewpoint of adhesion between the core material layer and the clad upper layer 15a, the photosensitive polymer material for forming the core material layer is a curable resin material for forming the clad upper layer 15a. Are preferably of the same type.

  Although the thickness of the said core material layer is not specifically limited, For example, it is preferable that it is about 20-100 micrometers.

  As a specific method of forming the core material layer, for example, a method of bonding a resin film to form the core material layer, a liquid curable resin material for forming the core material layer, Alternatively, a method of applying a varnish of a curable resin material is used.

  As a specific method of laminating a resin film to form the core material layer, for example, after placing the resin film made of a curable resin on the outer surface of the first cladding upper layer 15a, A resin film made of a curable resin is bonded to the outer surface of the clad upper layer 15a with a transparent adhesive.

  Further, as a specific method of applying a liquid curable resin material for forming the core material layer or a varnish of the curable resin material, a liquid curing is applied to the outer surface of the clad upper layer 15a. The varnish of the curable resin material or the curable resin material is applied using a spin coating method, a bar coating method, a dip coating method, or the like, and then dried as necessary.

  Before the core material layer is exposed and cured, the core material layer may be subjected to heat treatment. By doing so, unevenness, bubbles, voids and the like on the surface of the core material layer are eliminated and smoothed. The heat treatment temperature is preferably a temperature at which the unevenness, bubbles, voids, etc. on the surface of the core material layer disappear and become smooth, and is appropriately selected depending on the type of curable resin material forming the core material layer. The Moreover, as heat processing time, it is preferable that it is about 10 to 30 minutes from the point from which the said effect is fully acquired. The means for heat treatment is not particularly limited, and a method such as a method of treating in an oven set at a predetermined temperature or a method of heating with a hot plate is used.

  Next, the core material layer is irradiated with exposure light through a photomask to perform pattern exposure of a predetermined shape on the core material layer. Further, the exposure can be used without any particular limitation as long as it is a method of exposing light having a wavelength capable of deteriorating (curing, etc.) the photosensitive material with light with a necessary amount of light. Specifically, for example, a method of using energy rays such as ultraviolet rays as the exposure light may be used. In view of ease of handling, ultraviolet rays are preferably used. Also, contact exposure in which a photomask is placed so as to be in contact with the surface of the core material layer and exposure, and projection type in which exposure is performed while maintaining a predetermined interval so as not to contact the outer surface of the core material layer Any exposure method such as exposure may be used.

The exposure conditions are appropriately selected according to the type of photosensitive material. For example, the exposure light may be exposed to 500 to 3500 mJ / cm ² using a high-pressure mercury lamp as the exposure light. Is selected.

  Next, development processing is performed. As the development processing, when the photosensitive material of the core material layer is a positive type, an unexposed portion is washed away with a developer, and an unexposed portion is washed away with a developer in the case of a negative type. It is a process of removing. Examples of the developer include acetone, isopropyl alcohol, toluene, ethylene glycol, or a mixture of these at a predetermined ratio. Furthermore, for example, an aqueous developer as disclosed in JP-A-2007-292964 can be preferably used. Examples of the developing method include a method of spraying a developer by spraying and a method using ultrasonic cleaning.

  Thus, the core 14 is formed on the first cladding upper layer 15a. Next, as illustrated in FIG. 1B, mirror surfaces 10 and 10 for deflecting the guided light by 90 ° are formed at both ends of the core 14.

  Next, an inclined surface for reflecting light is formed on the core 14. The method is not particularly limited as long as an inclined surface described later can be formed. Here, the inclined surface means that light incident from the side opposite to the side of the core 14 in contact with the cladding upper layer 15a is guided into the core 14 or light emitted from the core 14 is transmitted to the cladding upper layer 15a. It is an inclined surface for reflecting light so as to be led out to the side opposite to the contact side. Specific methods for forming the inclined surface include, for example, a method of cutting with a dicing blade, a method by laser ablation, and the like.

  When cutting the core 14 with a blade, if necessary, the core 14 may be cut while being softened by heating the substrate 11 or the blade. Further, the cutting edge of the blade may be cut so as to reach the clad upper layer 15a or not.

  In addition, the mirror part which consists of a metal layer can also be formed on an inclined surface. The method for forming the mirror part is not particularly limited as long as it is a method of laminating a metal layer on an inclined surface. Specifically, the following method is mentioned, for example. First, a resist is applied to the inclined surface. Thereafter, UV irradiation is performed through a photomask or the like so that only the resist on the inclined surface is not removed by the development process. Then, only the resist on the inclined surface is left by performing development processing. Then, after performing an etching process, the resist is peeled off. By doing so, the mirror surface 10 made of a metal layer can be formed on the inclined surface. Moreover, when the mirror part 10 is formed by such a method, the mounting precision of the light receiving element, the light emitting element, etc. of the obtained photoelectric composite wiring board will be excellent.

  Next, as shown in FIG. 1C, a cladding lower layer 15b is further formed so as to embed the core portion 14 formed as described above.

  As a method for forming the cladding lower layer 15b, a resin film made of a curable resin material having a predetermined refractive index for forming the cladding lower layer 15b is bonded to the surfaces of the cladding upper layer 15a and the core 14. After that, a method of curing, a method of curing after applying a liquid curable resin material for forming the clad lower layer 15b, and a varnish of a curable resin material for forming the clad lower layer 15b The method of making it harden | cure after apply | coating is mentioned. In addition, when forming the said clad lower layer 15b, in order to improve adhesiveness, it is preferable to perform a plasma process etc. on the surface of the said core 14 previously.

  As a specific method for forming the cladding lower layer 15b, for example, the same method as that for the first cladding upper layer 15a described above can be used.

  Next, as shown in FIG. 1 (d), the cladding layer 15 formed so as to embed the core 14 on the surface of the substrate 16 is disposed on the side where the temporary substrate 16 'is not laminated (on the cladding lower layer side). ) To form.

  As the substrate 16, various organic substrates and inorganic substrates are used without particular limitation as in the above-described substrate 16 ′.

  Examples of the method for forming the clad layer 15 include a method in which the clad layer 15 is bonded to the surface of the substrate 16 and then cured. When forming the clad layer 15, it is preferable to perform plasma treatment or the like on the surface of the substrate 16 in advance in order to improve adhesion.

  The thickness of the cladding layer 15, that is, the thickness of the cladding upper layers 15 a and 15 b is not particularly limited, but is preferably about 5 to 15 μm, for example.

  Through the steps as described above, the optical waveguide 17 as shown in FIG. The formed optical waveguide 17 is formed by the core portion 14 and the clad layer 15, and the core portion 14 has a refractive index higher than that of the clad layer 15, and the light propagating through the core is reflected in the core by total reflection. It can be confined to. Such an optical waveguide 17 is mainly formed as a multimode waveguide. The size of the core portion 14 of the optical waveguide 17 is, for example, a rectangular shape of 20 to 100 μm, the thickness of the cladding layer 15 is 5 to 15 μm, respectively, and the refractive index difference between the core and the cladding layer is about 0.5 to 3%. Is suitable, but not limited to this.

<Metal layer lamination process>
Next, as shown in FIG. 1 (f), a metal layer containing an uncured resin composition in which a metal base material having a roughened surface on at least one side is laminated on the optical waveguide described above. Laminate.

  As a method for forming the metal layer, a method of bonding a resin film containing an uncured resin composition having a predetermined refractive index to the surface of the metal substrate 11 or a liquid resin composition is applied. Examples thereof include a method and a method of applying a varnish containing an uncured resin composition. In addition, when forming the said metal layer, in order to improve adhesiveness, it is necessary to surface-treat the said metal base material 11 previously, and to roughen the surface of at least one side.

  As a specific method of laminating a resin film made of an uncured resin composition for forming the metal layer, first, a resin film made of an uncured resin composition is stacked on the surface of the metal substrate 11. Examples of the method include a method in which the substrate is attached to the substrate by a heating press.

  Moreover, as a specific method of applying a liquid resin composition or a varnish containing a curable resin composition to form the clad material layer, for example, a liquid resin composition on the surface of the metal substrate 11 is used. Or a varnish containing an uncured resin material composition is applied using a spin coating method, a bar coating method, a dip coating method, or the like.

  As a method of applying the varnish of the uncured resin composition, first, the varnish is prepared by dissolving the uncured resin composition in a solvent and degassing under reduced pressure. There is a method of applying and drying the varnish on the surface of the substrate 16, and a method of laminating under high temperature and high pressure.

  As the resin composition, a resin composition whose refractive index at the transmission wavelength of guided light is lower than the material of the core 14 to be formed later is used. Examples of the refractive index at the transmission wavelength include those of about 1.5 to 1.55.

  The curable resin material for forming the metal layer is not particularly limited as long as it is a curable resin material having the same or lower refractive index at the transmission wavelength of the guided light than the material of the core 14. Usually, the same kind of curable resin material as that used to form the cladding layer 15 is used.

[Metal base material]
As the metal substrate 11, copper foil, aluminum foil, tungsten foil, iron foil, and the like can be used, and it is particularly preferable to use copper foil.

  Moreover, the said copper foil can select the copper foil according to required characteristics, such as a film thickness, surface roughness, and surface treatment.

  The metal base 11 needs to have at least one surface roughened. The method for roughening the surface of the metal substrate 11 can be performed by an appropriate method, and examples thereof include etching treatment and surface oxidation treatment. By performing the treatment, the anchor effect of the metal substrate 11 can be obtained, and the adhesion of the clad layer containing the above-described resin composition is improved.

  Moreover, what formed the barrier layer with zinc other than copper, nickel, etc. can also be used. Moreover, you may use what formed the antirust layer by the chromate process. Furthermore, it is also possible to use what formed the process by the silane coupling process in order to improve adhesiveness.

  The surface roughness Rz of the metal substrate 16 is preferably 0.5 μm or more and 5 μm or less, and more preferably 1 μm or more and 3 μm or less from the viewpoint of adhesion and patterning properties. When the surface roughness Rz is less than 0.5 μm, the anchor effect of the metal substrate is difficult to be obtained, so that the adhesion with the resin composition is lowered. On the other hand, if it is larger than 5 μm, it becomes difficult to obtain a fine pattern of the metal substrate.

  The thickness of the metal substrate 11 is preferably 3 μm or more and 50 μm or less, and more preferably 5 μm or more and 20 μm or less from the viewpoint of patterning properties and electrical characteristics. If the thickness of the metal base material 16 is less than 3 μm, the base material becomes difficult to handle, and a design is required in which the width must be increased in order to secure a resistance value, resulting in limitations. On the other hand, when the thickness is larger than 50 μm, time is required for metal patterning, and side etching is liable to occur, which causes a problem in quality stability.

  Next, as shown in FIG. 1G, the above-described metal layer is further laminated so that the core 14 is embedded.

  Examples of the method for laminating the metal layer include a method in which the uncured resin composition 12 laminated on the metal equipment is bonded so as to embed the core 14 and then cured by light, heat, or the like. .

<Metal layer formation process>
As shown in FIG. 1 (h), by curing the metal layer, the uncured resin composition 12 becomes a cured resin composition 13 formed so as to embed the core.

  As a method of curing the uncured resin composition 12, for example, heat treatment using an oven, a hot plate, or the like is used.

  Although it will not specifically limit if the thickness of the said cured resin composition 13 is high compared with the height of a core, For example, it is preferable that it is 10-30 micrometers. Further, the refractive index difference between the core and the second cladding layer is suitably about 0.5 to 3%, but is not limited thereto.

<Electric circuit formation process>
The electric circuit forming step is a step of forming an electric circuit 11a on the formed metal layer 11 as shown in FIG. The electric circuit 11a can be formed by, for example, a well-known etching technique for forming a circuit. Here, the boundary surface between the first cladding layer 13 and the electric circuit 11a is a rough surface, and the anchor effect is obtained by the unevenness (rough surface) formed in the electric circuit 11a. It is formed on the top with good adhesion. As described above, the photoelectric composite wiring board 17 including the optical circuit and the electric circuit 11a is obtained by this electric circuit forming step.

  As the electrical circuit formation processing, for example, through-hole processing, gold plating processing, or the like can be used in addition to the above-described etching processing. The alignment of the optical circuit and the electric circuit can be performed by using, for example, markings provided on the outer shape reference, the side surface of the substrate, or the back surface of the substrate.

The formed photoelectric composite wiring board 17 is formed of an uncured resin composition in which the core portion 14, the cladding layer 15 in which the core portion 14 is embedded, and a metal base material having a roughened surface on at least one side are laminated. The core portion 14 has a refractive index higher than that of the clad layer, and confins light propagating inside the core by total reflection. Such an optical waveguide 17 is mainly formed as a multimode waveguide. The size of the core portion 14 of the electric composite wiring board 17 is, for example, a rectangular shape of 20 to 100 μm, the lower first cladding layer 13 and the upper second cladding layer 12 excluding the thickness of the layer including the core portion. The thickness is suitably 5 to 15 μm, and the refractive index difference between the core portion and the clad layer is suitably about 0.5 to 3%, but is not limited thereto. In addition, the photoelectric composite wiring board 17 can be formed by forming the electric circuit 11 a using the metal substrate 11 on the second cladding layer 13.

  Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the present invention is not limited by the examples.

Example 1
First, the photoelectric composite wiring board in the manufacturing method of the present invention is manufactured.

<Manufacture of photoelectric composite wiring board>
Prior to manufacturing the optoelectric composite wiring board, a curable film for the first clad layer, a curable film for the core, and a curable film for the metal layer laminated second clad layer were prepared.

[Curable film for first cladding]
62 parts by mass of solid epoxy adduct (“EHPE3150” manufactured by Daicel Chemical Industries, Ltd.), 18 parts by mass of phenoxy resin (“YP50” manufactured by Tohto Kasei Co., Ltd.), trimethylolpropane type epoxy resin (“Epototo” manufactured by Toto Kasei Co., Ltd.) YH300 ") 8 parts by mass, 12 parts by mass of liquid bisphenol A type epoxy resin (" Epiclon 850S "manufactured by DIC), 0.5 parts by mass of photocationic curing agent (" SP-170 "manufactured by Adeka), heat 0.5 parts by mass of a cationic curing agent (“SI-150L” manufactured by Sanshin Chemical Industry Co., Ltd.) and 0.1 parts by mass of a surface conditioner (“F470” manufactured by DIC), 30 parts by mass of toluene and methyl ethyl ketone It is dissolved in a mixed solvent of 70 parts by mass, filtered through a membrane filter having a pore size of 1 μm, and then degassed under reduced pressure, whereby the clad epoxy resin composition is cooled. The scan was prepared. After applying this varnish on a PET film (“A4100” manufactured by Toyobo Co., Ltd.) using a multi-coater of a comma coater head manufactured by Hirano Techseed Co., Ltd., the solvent was removed and dried to obtain a thickness of 10 μm. A curable film for cladding was prepared. Further, a curable film for cladding having a thickness of 50 μm was prepared by changing the coating thickness of the varnish on the PET film. “OPP-MA420” manufactured by Oji Specialty Paper Co., Ltd. was thermally laminated as a protective film on the produced film.

[Curable film for core]
8 parts by mass of liquid 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate (“Celoxide 2021P” manufactured by Daicel Chemical Industries, Ltd.), solid epoxy adduct (“Daicel Chemical Industries, Ltd. EHPE3150 ") 12 parts by mass, solid bisphenol A type epoxy resin (" Epicoat 1006FS "manufactured by Japan Epoxy Resin) 37 parts by mass, trifunctional epoxy resin (" VG-3101 "manufactured by Mitsui Chemicals) 15 parts by mass , 18 parts by mass of a solid novolac type epoxy resin (“EPPN201” manufactured by Nippon Kayaku Co., Ltd.), 10 parts by mass of a liquid bisphenol A type epoxy resin (“Epiclon 850S” manufactured by DIC), a photocationic curing agent (manufactured by Adeka) "SP-170") 0.5 parts by mass, thermal cationic curing agent ("SI made by Sanshin Chemical Industry Co., Ltd." 150 L ") 0.5 parts by mass and 0.1 part by mass of a surface conditioner (" F470 "manufactured by DIC) were dissolved in a mixed solvent of 30 parts by mass of toluene and 70 parts by mass of methyl ethyl ketone, and the pore diameter was 1 µm. After filtering with a membrane filter, the varnish of the core epoxy resin composition was prepared by defoaming under reduced pressure. After applying this varnish on a PET film (“A4100” manufactured by Toyobo Co., Ltd.) using a multi-coater of a comma coater head manufactured by Hirano Techseed Co., the thickness was 40 μm by removing the solvent and drying. A core curable film was prepared. “OPP-MA420” manufactured by Oji Specialty Paper Co., Ltd. was thermally laminated as a protective film on the produced film.

[Second clad material layer laminated metal substrate]
62 parts by mass of (A) solid epoxy adduct (“EHPE3150” manufactured by Daicel Chemical Industries, Ltd.) and 18 parts by mass of phenoxy resin (“YP50” manufactured by Tohto Kasei Co., Ltd.) as a solid epoxy resin, liquid epoxy resin (C) 8 parts by mass of trimethylolpropane type epoxy resin (“Epototo YH300” manufactured by Toto Kasei Co., Ltd.) and (D) 12 parts by mass of liquid bisphenol A type epoxy resin (“Epiclon 850S” manufactured by DIC) E) 1.0 part by mass of “SP-170” manufactured by Adeka as photocationic curing agent, 0.5 part by mass of “SI-150L” manufactured by Sanshin Chemical Industry Co., Ltd. as thermal cationic curing agent, and (G) Mixing of 0.1 part by mass of “F470” manufactured by DIC as a surface conditioner with 30 parts by mass of (H) toluene and 70 parts by mass of (I) methyl ethyl ketone (MEK) The varnish of the epoxy resin composition for resin layers was prepared by making it melt | dissolve in a solvent at 60 degreeC under recirculation | reflux.

  This varnish was applied on a copper foil (“F2-WS” manufactured by Furukawa Electric Co., Ltd.) having a surface roughness Rz of 2.7 μm and a thickness of 12 μm using a multi coater of a comma coater head manufactured by Hirano Techseed. Then, the solvent was removed and dried to produce a second clad material layer laminated metal substrate having a thickness of 10 μm.

[Fabrication of optical waveguide]
The protective film is peeled off from the curable film for clad having a thickness of 10 μm, and this is subjected to ultraviolet rays under conditions of 50 ° C. and 0.2 MPa using a pressure type vacuum laminator (“V-130” manufactured by Nichigo Morton). The substrate was laminated on a 140 mm × 120 mm temporary substrate 1 made of a permeable polycarbonate resin. Using an ultra-high pressure mercury lamp, it is exposed to ultraviolet light under the condition of ² J / cm ² , and after peeling the PET film from the curable film for cladding, heat treatment is performed at 150 ° C. for 30 minutes, and oxygen plasma treatment The first clad upper layer 15a in which the clad curable film was cured was formed.

Next, the protective film is peeled off from the curable film for core having a thickness of 40 μm, and this is subjected to conditions of 60 ° C. and 0.2 MPa using a pressure type vacuum laminator (“V-130” manufactured by Nichigo Morton). Thus, the first clad layer 15 was laminated. A negative mask on which core pattern slits (slit widths of 40 μm and slit lengths of 120 mm) are formed is placed on a core curable film, and an ultra-high pressure mercury lamp is used for ultraviolet irradiation under conditions of 4 J / cm ^2. After exposure to light, the negative mask is removed, the PET film is peeled off from the core curable film, heat treatment is performed at 140 ° C. for 10 minutes, and a water-based flux cleaning agent adjusted to 55 ° C. as a developer (Arakawa) By developing using “Pine Alpha ST-100SX” manufactured by Chemical Industry Co., Ltd., the unexposed / uncured portion of the curable film for the core is dissolved and removed, and after finishing washing with water and air blowing, By drying at 100 ° C. for 10 minutes, the exposed portion of the core curable film was cured according to the core pattern. 14 was formed on the first clad upper layer 15a (see Figure 1 (a)).

  Here, when the surface state of the first cladding 2 was visually observed, no roughness was observed on the surface of the first cladding layer 15. Further, when the appearance of the core 14 was observed with a stereomicroscope, no roughness was observed on the side wall of the core 14.

Next, a micromirror for deflecting the guided light by 90 ° was formed at a position 10 mm from both ends of the core 14. That is, first, a rotating blade having a cutting blade apex angle of 90 ° (“# 5000” blade manufactured by Disco Corporation) is applied from both ends of the core 14 at a rotational speed of 10,000 rpm and a moving speed of 0.1 mm / s. Each V-groove having a depth of 50 μm was formed by moving across a position of 10 mm. Next, a diluted solution obtained by diluting a varnish of an epoxy resin composition for a clad prepared for producing a curable film for a clad 50 times with a mixed solvent of 30 parts by mass of toluene and 70 parts by mass of methyl ethyl ketone is added to the V groove. After thinly applying with a brush and drying at 100 ° C. for 30 minutes, using an ultra-high pressure mercury lamp, exposure is performed by irradiating with ultraviolet light under the condition of 1 J / cm ² , and further heat treatment is performed at 120 ° C. for 10 minutes. The V groove was smoothed. Next, a gold thin film having a thickness of 1000 mm was formed on the surface of the V-groove by covering the metal mask with only the V-groove portion opened and vacuum-depositing gold, thereby forming the mirror surface 10 of the micromirror. (See FIG. 1 (b)).

Next, the protective film is peeled off from the curable film for cladding having a thickness of 50 μm, and this is subjected to conditions of 80 ° C. and 0.3 MPa using a pressure type vacuum laminator (“V-130” manufactured by Nichigo Morton). Then, the first clad 15b and the core 14 were laminated on the first clad 15b and the core 14 (see FIG. 1C). The PET film is peeled off from the curable film for clad, and a pressure type vacuum laminator (“V-130” manufactured by Nichigo Morton) is used on the peeled surface under the conditions of 80 ° C. and 0.2 MPa, A substrate 16 (“FR4” manufactured by Panasonic Electric Works Co., Ltd.) was laminated (see FIG. 1D). From the temporary substrate 16 'side, an ultra-high pressure mercury lamp is used to irradiate with ultraviolet light under the condition of ² J / cm ² , and then heat treatment is performed at 140 ° C. for 1 hour, whereby the curable film for cladding is cured. The second clad material 12 was formed. By removing the temporary substrate 16 ′, the optical waveguide 17 having the core 14 and the clad 15 enclosing the core 14 was obtained in a state of being bonded to the substrate 16 (see the lower part of FIG. 1 (e)).

[Clad layer forming process]
Next, the protective film is peeled off from the second clad layer laminated metal base material having a thickness of 10 μm, and this is applied to a pressure-type vacuum laminator (“V-130” manufactured by Nichigo-Morton) at 60 ° C., 0. It laminated | stacked on the produced optical waveguide 17 on the conditions of 2 MPa (refer FIG.1 (g)).

[Second cladding layer forming step]
By performing heat treatment at 150 ° C. for 30 minutes, the first cladding layer 13 in which the first cladding material layer was cured was formed (see FIG. 1H).

[Electric circuit formation process]
The formed metal layer 11 is formed on an electric circuit 11a having a predetermined pattern by an etching technique, and after further forming a solder resist, gold plating treatment and silk printing are performed, whereby an optical circuit (optical waveguide 17) and an electric circuit 11a An opto-electric composite wiring board 18 having the above was obtained (see FIG. 1I). The peel strength of this metal layer was 0.6 N / mm, which was a practical level.

(Comparative Example 1)
The clad material was cured in a substrate shape, and electroless plating and electrolytic plating were applied thereon to form a 12 μm copper foil. The surface roughness was 0.1 μm. This copper foil was peeled from the substrate. In producing the second clad layer laminated metal base material, an optoelectric composite wiring board was prepared in the same manner as in Example 1 except that a copper clad was used to form a second clad material layer of about 10 μm by a bar coater. Created.

<Evaluation of loss of photoelectric composite wiring board>
The loss evaluation of the photoelectric composite wiring board 18 obtained in Example 1 was performed. That is, light (850 nm wavelength) from a VCSEL (Vertical Cavity Surface Emitting Laser), which is a light emitting / receiving element, passes through an optical fiber having a core diameter of 10 μm and NA of 0.21 to the optical waveguide 17 (optical circuit) of the photoelectric composite wiring board 18. The power of light (incident on one mirror surface 10 through matching oil (silicone oil) and emitted from the other mirror surface 10 through the same matching oil through an optical fiber having a core diameter of 200 μm and NA 0.4 ( P1) was measured with a power meter. Further, the power (P0) of the light emitted without directly inserting the second cladding layer 15 and the optical waveguide 17 of the photoelectric composite wiring board 18 by directly abutting the ends of the two optical fibers is measured with a power meter. It was measured. Then, the insertion loss of the photoelectric composite wiring board 18 was obtained from the calculation formula of “(−10) log (P1 / P0)”, which was as small as 2.2 dB and was sufficiently practical.

  On the other hand, the peel strength of the copper foil in the insertion loss of the photoelectric composite wiring board obtained in Comparative Example 1 was 0.1 N / mm, and it was not at a practical level. This is considered to be because the surface roughness Rz of the used metal substrate was smaller than 0.5 μm.

  As described above in detail with reference to specific examples, in the method of manufacturing an opto-electric composite wiring board 18 including the optical circuit 17 and the electric circuit 11a, an optical waveguide for forming a clad in which a core 14 is embedded on a substrate 16. A metal layer laminating step of laminating an uncured resin composition 12 in which a metal base 11 having a surface roughened at least on one side is laminated on the opposite side of the substrate 16 of the optical waveguide; Since there are provided a metal layer forming step of curing the cured resin composition 12 to form a metal layer and an electric circuit forming step of forming an electric circuit on the metal base material 11, the outer side of the metal base material 11 is provided. Asperities (rough surfaces) exist on the surface, and the adhesion of the electric circuit 11a is improved. Further, since the transparency of the cladding layer 15 is at a level that does not cause a problem in practice, the coupling loss between the light receiving / emitting element such as a VCSEL on the electric circuit 11a and the optical waveguide 17 is suppressed.

  Further, since the metal base material 11 in which the uncured resin composition 12 is laminated on the optical waveguide 17 that has already been built is built up, the side wall of the core 14 is not roughened, and the waveguide loss of the optical waveguide 17 is reduced. It is suppressed. Moreover, the optical waveguide 17 is manufactured by build-up on the substrate 16 instead of the manufacturing method in which the optical circuit 17 and the electric circuit 11a are separately manufactured and then bonded together. Since this is a manufacturing method in which the circuit 17 and the electric circuit 11a are combined, the photoelectric composite wiring board 18 can be obtained with a high yield.

  Moreover, when laminating | stacking the resin composition film (2nd clad layer film) containing an epoxy resin at a 2nd clad layer formation process, it is conventionally used for manufacture of a printed wiring board or manufacture of the optical waveguide 17. FIG. Since it can respond to facilities with a mass production record such as a vacuum laminator, the productivity of the metal-clad laminate and the photoelectric composite wiring board 18 is improved.

  Further, since the second clad layer 15 contains a solid epoxy resin and a liquid epoxy resin as epoxy resins, the properties of the resin composition are diversified, and desired properties (including refractive index) are obtained by combining the epoxy resin components. ) Resin composition can be obtained.

DESCRIPTION OF SYMBOLS 10 Mirror surface 11 Metal base material 11a Electric circuit 12 Uncured resin composition 13 Cured resin composition 14 Core part 15 Cladding layer 15a Cladding upper layer 15b Cladding lower layer 16 Substrate 17 Optical waveguide 18 Optoelectronic composite wiring board

Claims (5)

An optical waveguide forming step of forming a clad with a core embedded on a substrate;
A metal layer laminating step of laminating an uncured resin composition in which a metal base material having a roughened surface at least on one side is laminated on the opposite side of the substrate of the optical waveguide;
A metal layer forming step of curing the uncured resin composition to form a metal layer;
And an electric circuit forming step of forming an electric circuit on the metal substrate.   The surface roughness Rz of the said metal base material is 0.5 micrometer or more and 5 micrometers or less, The manufacturing method of the photoelectric composite wiring board of Claim 1 characterized by the above-mentioned.   The method for producing an optoelectric composite wiring board according to claim 1 or 2, wherein the refractive index of the uncured resin composition is the same as or lower than the refractive index of the core.   The said resin composition is a dry film, The manufacturing method of the photoelectric composite wiring board of any one of Claims 1-3 characterized by the above-mentioned.   An opto-electric composite wiring board obtained by the method for manufacturing an opto-electric composite wiring board according to any one of claims 1 to 4.

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