JP3843861B2 - Optical / electric composite substrate and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical / electrical composite substrate capable of transmitting an optical signal and an electrical signal, and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, advanced information technology has been rapidly progressing, and the era of high-speed networks of gigabit and terabit class is coming. Under these circumstances, high-speed performance is required for information processing terminal devices that support networks. One of the answers to this requirement is a high-speed transmission technique using light, and it has been studied to fuse electrical signal transmission and optical signal transmission.
[0003]
Various optical / electric composite wiring boards that combine an optical transmission line and an electric circuit board have been proposed in order to combine optical transmission and electric signal transmission.
[0004]
[Problems to be solved by the invention]
Conventionally proposed optical / electrical composite wiring boards are generally made by individually fabricating an optical transmission line and an electric wiring board and combining them together. However, in this case, both the production of the electrical wiring board and the production process of the optical transmission line are necessary, and there is a problem that it takes time and cost.
[0005]
The present invention has been made in view of the above points, and can transmit both an optical signal and an electric signal with a single substrate, and can reduce the manufacturing cost and the manufacturing time. An object of the present invention is to provide a composite optical / electrical substrate.
[0006]
[Means for Solving the Problems]
Optoelectronic composite substrate according to claim 1 of the present invention includes a core layer 1 made of a transparent resin 1a, a cladding layer 2 which the refractive index than the core layer 1 is made of a lower transparent resin 2a, light having an electrical insulating property In addition to forming the wave layer 3, the conductive metal layer 4 is formed on the surface of the optical waveguide layer 3, and the cladding layer 2 is formed by lamination molding of the prepreg 6 prepared by impregnating the base material 5 with the transparent resin 2 a. The base material 5 is arranged in a position deviated on the opposite side to the core layer 1 in the clad layer 2 .
[0009]
The invention of claim 2 is characterized in that, in claim 1 , as the transparent resin 2a forming the clad layer 2, a resin having higher heat resistance than the transparent resin 1a forming the core layer 1 is used.
[0011]
According to a third aspect of the present invention, in the first or second aspect , the optical path changing means 7 is provided in a part of the core layer 1, and light is transmitted through the cladding layer 2 and the conductive metal layer 4 in the portion where the optical path changing means 7 is provided. The feature is that the portion 8 is formed.
[0012]
The invention of claim 4 is characterized in that, in claim 3 , the lens 9 is formed of the transparent resin 2a of the cladding layer 2 in the light passage portion 8.
[0013]
The invention of claim 5 is characterized in that, in claim 3 , an element 14 having a lens function is added to the light passage portion 8.
[0014]
According to a sixth aspect of the present invention, there is provided a method for producing an optical / electrical composite substrate comprising: a resin sheet 10 made of a transparent resin 1a; and the optical / electrical composite substrate according to any one of the first to fifth aspects. The prepreg 6 prepared by impregnating the base material 5 with the transparent resin 2a having a refractive index lower than that of the resin sheet 10 and the metal foil 11 are stacked, and this is heated and pressed to form a laminate. .
[0015]
The invention of claim 7, in claim 6, in manufacturing the optical-electrical composite substrate according to any of the above claims 3 to 5, a substrate in a portion forming the light-passing section 8 as prepregs 6 5 The one having holes 12 is used.
[0016]
Further, the invention of claim 8 is the invention according to claim 6, wherein in manufacturing the optoelectric composite substrate according to any one of claims 3 to 5 , in the portion where the light passage portion 8 is formed after the lamination molding. A hole 13 extending from the metal foil 11 to the cladding layer 2 is processed, and the hole 13 is filled with a transparent resin 2b having a refractive index equivalent to that of the transparent resin 2a of the cladding layer 2.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0018]
FIG. 1A is a reference diagram for explaining the present invention , in which an optical waveguide layer 3 having electrical insulation is formed by laminating clad layers 2 on both surfaces of a core layer 1, and each clad of the optical waveguide layer 3 is formed. A conductive metal layer 4 is provided on the outer surface of the layer 2 to form an optical / electric composite substrate.
[0019]
The core layer 1 and the clad layer 2 are formed of transparent resins 1a and 2a, respectively, and the thickness is preferably set in the range of several tens to several hundreds of μm. The transparent resin 1a for forming the core layer 1 and the transparent resin 2a for forming the cladding layer 2 are preferably those having the same transparency. For example, fluorinated polyimide, cycloolefin copolymer, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET) ) Etc. can be used. The transparent resin 1a that forms the core layer 1 uses a resin having a higher refractive index than the transparent resin 2a that forms the cladding layer 2. For example, when PMMA is used as the transparent resin 2a that forms the cladding layer 2, the core layer 1 A cycloolefin copolymer is used as the transparent resin 1a forming 1.
[0020]
As described above, the optical waveguide layer 3 is formed of the core layer 1 made of the transparent resin 1a having a high refractive index and the clad layer 2 made of the transparent resin 2a having a low refractive index. The optical signal can be transmitted by propagating light along the optical waveguide layer 3 while being totally reflected at the interface of the cladding layer 2. Since the optical waveguide layer 3 made of the transparent resins 1a and 2a has electrical insulation, an electric circuit can be formed by the conductive metal layer 4 formed on the surface of the optical waveguide layer 3, and an electric signal can be transmitted. It is something that can be done.
[0021]
The conductive metal layer 4 can be formed of a metal foil such as a copper foil or an aluminum foil, but can also be formed by metal plating or the like. Further, in the embodiment of FIG. 1A, the structure is a double-sided circuit board in which the conductive metal layer 4 is provided on both sides, but it can also be formed in the structure of a multilayer circuit board.
[0022]
In the embodiment of FIG. 1A, the core layer 1 is formed by a resin sheet 10 made of a transparent resin 1a, and the cladding layer 2 is made by impregnating and drying the transparent resin 2a on a base material 5 such as a glass cloth. Thus, the base material 5 is embedded in the clad layer 2. By forming the cladding layer 2 with the prepreg 6 having the base material 5 in this way, the strength of the optical waveguide layer 3 can be increased by the reinforcing action of the base material 5 and the dimensional stability can be increased. An optical / electric composite substrate having excellent dimensional stability can be obtained.
[0023]
FIG. 1 (b) shows one step in producing an optical / electric composite substrate. The base sheet 5 is impregnated with the transparent resin 2a and dried on both surfaces of the resin sheet 10 made of the transparent resin 1a. The prepreg 6 prepared in a B-stage state is overlaid, and further, a metal foil 11 is overlaid on the outer side, and this is heated and pressed to form a laminate layer. An optical / electric composite substrate in which the laminated optical waveguide layer 3 is formed and the conductive metal layer 4 made of the metal foil 11 is laminated and integrated on the surface of the clad layer 2 can be manufactured. In this manner, an optical / electric composite substrate having both functions of optical transmission and electric signal transmission can be manufactured by laminating by heating and pressing in the same manner as a normal electric wiring board.
[0024]
Here, when forming the clad layer 2 with the prepreg 6 having the base material 5, if the base material 5 exists in the vicinity of the interface between the clad layer 2 and the core layer 1, the base material 5 is formed at the interface between the core layer 1 and the clad layer 2. As a result, light is diffusely reflected, and the light transmission efficiency in the optical waveguide layer 3 may be reduced. Therefore, in the present invention, as in the embodiment of FIG. 2 , the base material 5 is arranged in the clad layer 2 at a position deviated from the core layer 1 by several tens to several hundreds μm on the conductor metal layer 4 side. Thus, the base material 5 is not exposed in the vicinity of the interface between the cladding layer 2 and the core layer 1 to reduce the light transmission efficiency. The biasing of the base material 5 can be performed in either one or both of the clad layers 2 on both sides of the core layer 1. In order to form the clad layer 2 in which the base material 5 is biased in this way, for example, the base material 5 is impregnated with the transparent resin 2a, and the transparent resin 2a is further applied to one side of the base material 5, and the base material 5 The prepreg 6 prepared so that the layer of the transparent resin 2a on one side surface is thick and the layer of the transparent resin 2a on the other side surface is thin is used. The prepreg 6 is formed on the resin sheet 10 on the side where the layer of the transparent resin 2a is thick. It is possible to carry out by performing the above-mentioned heat and pressure molding again.
[0026]
Further, it is preferable to use a transparent resin 2 a that forms the cladding layer 2 that has higher heat resistance than the transparent resin 1 a that forms the core layer 1. Since the clad layer 2 is laminated on both sides of the core layer 1, a heat resistant shell that protects the core layer 1 by using a material having high heat resistance as the clad layer 2, that is, a material having a high heat deformation temperature, a heat discoloration temperature, or the like. The structure can be formed, and the selection range of the transparent resin 1a forming the core layer 1 can be widened. For example, a fluorine-based high heat-resistant resin such as fluorinated polyimide or Teflon (registered trademark) can be used as the resin for the cladding layer 2, and polycarbonate, transparent epoxy resin, PMMA resin, or the like can be used as the resin for the core layer 1.
[0027]
FIG. 3 shows a reference example for explaining the present invention, and an optical path changing means 7 for changing the optical path of light transmitted along the surface direction to the core layer 1 of the optical waveguide layer 3 in the thickness direction of the core layer 1. Is provided in a part of the core layer 1. The optical path changing means 7 can be formed by drawing a grating for diffracting light on the core layer 1 or providing an optical element such as a micromirror or a prism on the core layer 1. By diffracting, reflecting, refracting, etc., the light transmitted through 1, the light optical path can be changed in the thickness direction of the optical / electric composite substrate. Thus, by changing the optical path of the light in the thickness direction, the light transmitted along the core layer 1 can be taken out from the surface of the optical / electrical composite substrate. When passing through the clad layer 2 in the thickness direction, when the base material 5 is embedded in the clad layer 2, the light is scattered by the base material 5 and reflected by the conductive metal layer 4 to extract the light to the outside. I can't. Therefore, a light passage portion 8 is formed in the clad layer 2 and the conductive metal layer 4 in the portion where the optical path changing means 7 is provided, and light is extracted through the light passage portion 8 to the outside of the optical / electric composite substrate. That is, the hole 12 is provided in the base material 5 of the clad layer 2 in the portion where the optical path changing means 7 is provided, and the hole 17 is provided in the same portion in the conductive metal layer 4 so that the transparent in the hole 12 of the base material 5 in the clad layer 2 The resin 2a and the hole 17 of the conductive metal layer 4 form a light passage portion 8 through which light passes.
[0028]
FIG. 4 shows an example of a method of manufacturing an optical-electrical composite substrate where the light-passing section 8 formed as described above, FIG. 4 which was prepared by first impregnating and drying a transparent resin 2a to the substrate 5 ( using prepreg 6 such as a), drilling holes 12 as shown in Figure 4 (b) in place to form the light-passing section 8. Thus, the base material 5 can be removed from the prepreg 6 in the portion where the holes 12 are formed. Here, the base material 5 having the holes 12 formed therein may be used, and the prepreg 6 prepared by impregnating and drying the transparent resin 2a on the base material 5 having the holes 12 formed therein may be used. Next, overlapping metal foil 11 further outside thereof with overlapping prepregs 6 on both surfaces of the resin sheet 10 manufactured in transparent resin 1a as shown in FIG. 4 (c). At this time, the prepreg 6 having no holes 12 is used on the side from which light is not extracted. And by laminating molding it by heating and pressing, as shown in FIG. 4 (d), forming an optical waveguide layer 3 and the cladding layer 2 integrally laminated by prepregs 6 on both sides of the core layer 1 by the resin sheet 10 In addition, the conductive metal layer 4 made of the metal foil 11 can be laminated and integrated on the surface of the clad layer 2, and the transparent resin impregnated in the holes 12 of the prepreg 6 at the time of the heat and pressure molding. 2a flows in and is filled, and the light passing portion 8 made of only the transparent resin 2a can be formed in the clad layer 2. Thereafter, when a circuit is formed by performing etching processing or the like on the metal foil 11, the light passage portion 8 is also provided in the metal foil 11 by providing a hole 17 in the metal foil 11 in the portion of the light passage portion 8. Thus, an optical / electric composite substrate as shown in FIG. 3 can be obtained.
[0029]
As a method of the core layer 1 providing the light path changing means 7, and how is embedded optical elements in advance, mirror or prism in the resin sheet 10 prior to lamination molding process of FIG. 4 (c), the cladding layer 2 and after forming the light passage part 8 on the metal foil 11, a method of forming a grating on the transparent resin 1a of the core layer 1 using a difference in quality of the transparent resins 1a and 2a due to energy irradiation, and the like. In the latter method, for example, a femtosecond pulse laser can be used as the energy irradiation.
[0030]
FIG. 5 shows another example of the method for producing the optical / electrical composite substrate having the light passing portion 8 as described above. The resin sheet 10 made of the transparent resin 1a as shown in FIG. 5 (a). 5 (b) by stacking the prepreg 6 prepared by impregnating and drying the transparent resin 2a on the base material 5 on both sides of the substrate 5 and further stacking the metal foil 11 on the outside and heating and pressurizing it. The optical waveguide layer 3 in which the clad layer 2 made of the prepreg 6 is laminated and integrated is formed on both sides of the core layer 1 made of the resin sheet 10 and the conductive metal layer 4 made of the metal foil 11 is laminated and integrated on the surface of the clad layer 2. To do. Then perform the drilling or laser machining at a point to form the light-passing section 8, it is bored a hole 13 extending from the metal foil 11 to the cladding layer 2 as shown in FIG. 5 (c). As shown in FIG. 5 (d) Thereafter, the transparent resin 2a and the refractive index and transparency of the cladding layer 2 is filled by pouring the same transparent resin 2b into the hole 13. In this way, the light passage portion 8 can be formed by the portion of the clad layer 2 made of only the transparent resin 2b and the hole 13 of the metal foil 11.
[0031]
To a method of forming an optical path conversion means 7 into the core layer 1, and a method to be provided an optical path changing unit 7 in advance the resin sheet 10 prior to lamination molding process of FIG. 5 (a), FIG. 5 (c) There is a method of providing the optical path changing means 7 from the hole 13 to the core layer 1 after processing the hole 13 as described above. As the optical path changing means 7, the one described above can be used. When the transparent resin 2b embedded in the hole 13 of the cladding layer 2 has a slightly higher refractive index than that of the transparent resin 2a of the cladding layer 2, the light passing through the light passage portion 8 formed by the transparent resin 2b is transparent resin. It is transmitted while being totally reflected at the interface between 2b and the transparent resin 2a, and light can be efficiently extracted outside the optical / electrical composite substrate without escaping from the outer periphery of the light passage portion 8. .
[0032]
In the embodiment of FIG. 6 , a lens 9 is formed in the light passage portion 8 of the cladding layer 2. By forming the lens 9 in the light passage portion 8 in this way, the light can be condensed and efficiently extracted outside the optical / electric composite substrate. As a method of forming the lens 9 in the light passage portion 8 of the cladding layer 2, the surface of the transparent resin 2a (or the transparent resin 2b) of the light passage portion 8 is processed into a lens shape, or the resin is altered to change the grating lens. There is a method of processing.
[0033]
In the embodiment of FIG. 7 , an element 14 having a lens function is added to the light passage portion 8, and the light is condensed by the element 14 having the lens function and efficiently extracted outside the optical / electrical composite substrate. It is made to be able to. The element 14 having a lens function are those that can be used as the microlenses, for example, after processing a hole 13 as shown in FIG. 5 (c), the insert element 14 having a lens function to the hole 13 The element 14 having a lens function can be attached to the light passage 8 by being filled with the transparent resin 2b.
[0034]
【The invention's effect】
As described above, the optical / electric composite substrate according to claim 1 of the present invention is an optical waveguide having an electrical insulation property from the core layer made of transparent resin and the clad layer made of transparent resin having a refractive index lower than that of the core layer. Since the layer is formed and the conductive metal layer is formed on the surface of the optical waveguide layer, the optical signal can be transmitted along the optical waveguide layer by total reflection at the interface between the core layer and the cladding layer. An electrical signal can be transmitted by a conductive metal layer formed on the surface of an optical waveguide layer having electrical insulation, and both an optical signal and an electrical signal can be transmitted by a single substrate. is there. Moreover, by laminating the transparent resin or conductive metal layer forming the core layer or the cladding layer, it is possible to manufacture a substrate that transmits both an optical signal and an electric signal, and the manufacturing cost can be reduced. Manufacturing time can be shortened.
[0035]
Also, the cladding layer is so formed by laminate molding of a prepreg prepared by impregnating a transparent resin substrate, it is possible to enhance the dimensional stability it is possible to increase the strength by the reinforcing effect of the substrate Thus, an optical / electric composite substrate excellent in strength and dimensional stability can be obtained.
[0036]
Also, the substrate because it is located at a position offset on the opposite side of the core layer in the cladding layer, it is possible to prevent the base material is exposed in the vicinity of the interface between the cladding layer and the core layer, the core layer It is possible to prevent a decrease in transmission efficiency when transmitting light by being totally reflected at the interface of the cladding layer.
[0037]
The invention of claim 2 is the transparent resin for forming the clad layer according to claim 1, wherein the transparent resin having a higher heat resistance than the transparent resin for forming the core layer is used. The layer can be thermally protected, and the range of selection of the transparent resin forming the core layer can be widened.
[0039]
Further, in the invention of claim 3 , in claim 1 or 2 , the optical path changing means is provided in a part of the core layer, and the light passing part is formed in the clad layer and the conductive metal layer in the portion where the optical path changing means is provided. The optical path of the light transmitted by being totally reflected at the interface between the core layer and the clad layer can be taken out from the light passage section by changing the optical path with the optical path conversion means.
[0040]
According to a fourth aspect of the present invention, since the lens is formed of the transparent resin of the cladding layer in the light passage portion in the third aspect , the light can be condensed by the lens and efficiently taken out to the outside. is there.
[0041]
Further, the invention of claim 5 is that, in claim 3 , since an element having a lens function is added to the light passage portion, the light can be condensed by the element having a lens function and efficiently extracted to the outside. Is.
[0042]
According to a sixth aspect of the present invention, there is provided a method for producing an optical / electrical composite substrate comprising: a resin sheet made of a transparent resin; and a resin in producing the optical / electrical composite substrate according to any one of the first to fifth aspects. Since the prepreg prepared by impregnating the base material with a transparent resin having a lower refractive index than the sheet and the metal foil are layered and laminated by heating and pressing, the resin sheet, the prepreg and the conductive metal layer are heated. By applying pressure and laminating, it is possible to manufacture a substrate that transmits both an optical signal and an electric signal using the conventional method of forming an electric wiring board as it is, and the manufacturing cost can be reduced. In addition, the manufacturing time can be shortened.
[0043]
The invention of claim 7, in claim 6, in manufacturing the optical-electrical composite substrate according to any of the above claims 3 to 5, a hole in the substrate in the portion forming the light-passing section as prepreg Since the material used is open, it is possible to prevent the base material from being present in the light passage part of the clad layer, and the light is not scattered or absorbed by the base material. High light can be extracted.
[0044]
Further, in the invention of claim 8 , in manufacturing the optoelectric composite substrate according to any of claims 3 to 5 in claim 6 , after the lamination molding, the portion that forms the light passage portion is made of a metal foil. Since the hole reaching the cladding layer is processed, and the hole is filled with a transparent resin having a refractive index equivalent to that of the transparent resin of the cladding layer, the base material does not exist in the light passage portion of the cladding layer. The light can be efficiently extracted through the light passage portion without being scattered or absorbed by the base material.
[Brief description of the drawings]
FIG. 1 shows a reference example for explaining the present invention, in which FIG. 1 (a) is a front view of an optical / electric composite substrate, and FIG. 1 (b) is an exploded front view in one process of manufacturing the same.
2 is a front view of an optical-electrical composite substrate showing an example of implementation of the embodiment of the present invention.
FIG. 3 is a front view of an optical / electric composite substrate showing a reference example for explaining the present invention;
FIG. 4 shows an example of an embodiment for manufacturing an optical / electric composite substrate, and (a) to (d) are front views, respectively.
FIGS. 5A and 5B show an example of another embodiment for manufacturing an optical / electric composite substrate, and FIGS. 5A to 5D are front views, respectively. FIGS.
FIG. 6 is a front view of an optical / electric composite substrate showing a reference example for explaining the present invention.
FIG. 7 is a front view of an optical / electric composite substrate showing a reference example for explaining the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Core layer 1a Transparent resin 2 Cladding layer 2a Transparent resin 2b Transparent resin 3 Optical waveguide layer 4 Conductive metal layer 5 Base material 6 Prepreg 7 Optical path changing means 8 Light passage part 9 Lens 10 Resin sheet 11 Metal foil 12 Hole 13 Hole 14 Lens Functional device

Claims (8)

A core layer made of a transparent resin, and a cladding layer having a refractive index than the core layer is lower than the transparent resin, thereby forming a light waveguide layer having an electrical insulating property, and forming a conductive metal layer on the surface of the optical waveguide layer, The clad layer is formed by laminating a prepreg prepared by impregnating a transparent resin into a base material, and the base material is disposed in a position biased to the opposite side of the core layer in the clad layer.・ Electric composite board. As the transparent resin forming the cladding layer, the light-electrical composite substrate according to claim 1, characterized in Rukoto used as high heat resistance than the transparent resin forming the core layer. 3. The optical / electrical composite according to claim 1 , wherein an optical path changing means is provided in a part of the core layer, and a light passing portion is formed in the clad layer and the conductive metal layer in the portion provided with the optical path changing means. substrate. 4. The optical / electric composite substrate according to claim 3 , wherein a lens is formed of a transparent resin of a clad layer in the light passage portion . 4. The optical / electric composite substrate according to claim 3 , wherein an element having a lens function is added to the light passage portion. In manufacturing the optical / electric composite substrate according to any one of claims 1 to 5, a resin sheet made of a transparent resin, a prepreg prepared by impregnating a base material with a transparent resin having a refractive index lower than that of the resin sheet, A method for producing an optical / electric composite substrate, comprising: stacking a metal foil and heating and pressing the metal foil to form a laminate . 6. The optical / electric composite substrate according to claim 3, wherein a substrate having a hole in a portion where a light passage portion is formed is used as a prepreg. The manufacturing method of the optical / electrical composite board | substrate of description . In manufacturing the optical / electrical composite substrate according to any one of claims 3 to 5 , after lamination molding, a hole from the metal foil to the cladding layer is processed in a portion where the light passage portion is formed, and the hole is formed in the hole. The method for producing an optical / electric composite substrate according to claim 6 , wherein a transparent resin having a refractive index equivalent to that of the transparent resin of the cladding layer is filled .

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