JP2003172828A - Photoelectric composite substrate, wiring method of optical fiber, and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] (Modifications) [Problem] To provide an opto-electric composite substrate capable of high-density mounting of electric and optical wiring, and a method of manufacturing the same. An optical fiber coated with a thermosetting resin in advance is used as means for forming an optical wiring between interlayer portions of an electric wiring board. In order to wire the optical fiber 7, the metal 2 is etched into an optical wiring shape. At this time, if the gap width between the etched conductor layer and the conductor layer is made smaller than the diameter of the optical fiber 7, the optical fiber 7 is temporarily fixed by being pushed into the gap between the conductor layer and the optical fiber 7. The thermosetting resin coated on the fiber 7 is temporarily fixed by partially welding. Next, a plurality of multi-layer copper-clad laminates on which optical wirings are formed by the above-described method together with electric wirings are bonded by prepregs 8. By etching the thermosetting resin portion on the end surface of the multilayer board after bonding, the end portion of the fiber core wire is re-exposed from the end surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optoelectric composite substrate in which an optical wiring and an electric wiring are formed on the same printed wiring board, an optical fiber wiring method, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a method of laying optical wiring, particularly an optical fiber on a printed wiring board, there is a method of laying wiring on the front and back of the printed wiring board. For example, there are known a structure for fixing an optical fiber on a printed wiring board by using a fixing terminal and a structure for fixing the optical fiber in an optical fiber fixing groove formed of a resin layer on the printed wiring board. Japanese Utility Model Laid-Open No. 5-20004 is cited as an example of the former, and Japanese Patent Laid-Open No. 2001-59911 is cited as an example of the latter.

Further, a method is known in which an optical fiber is embedded in an insulating layer by transfer molding and optical wiring is performed, and an example thereof is Japanese Patent Laid-Open No. 2000-147270.

[0004]

However, when the fixing terminal is mounted on the printed wiring board, it is necessary to fix the optical fiber at several points in consideration of the radius of curvature so that the bending loss of the optical fiber does not occur. is there. For this reason, there is a problem that the mounting area of the fixing terminal hinders wiring and component mounting, which makes high-density wiring difficult. In addition, when fixing in the optical fiber fixing groove formed of a resin layer on the printed wiring board, the number of parts of the fixing terminal can be reduced, but the fixing groove inside part interferes with wiring and component mounting. Was there. Further, when the optical fibers are laid on the printed wiring board, there are only the front and back surfaces of the printed wiring board on which the optical fibers are mounted, and the number of wirings is limited.

Furthermore, when the optical fiber is embedded in the insulating layer by transfer molding, there is no pattern serving as a guide for wiring the optical fiber and the optical fiber is not temporarily fixed, so the optical fiber moves during molding. However, there is a problem that the position accuracy becomes poor.

In addition, the following problems can be considered when wiring the optical fiber between the layers of the electric wiring board. That is, in the bonding step, the melted prepreg does not sufficiently fill the gap between the optical fiber and the conductor layer, and resin unfilling called a laminated void occurs. The optical fiber moves between the wiring and the completion of the bonding, and the positional accuracy of the wiring deteriorates. In an outer shape cutting operation for finishing to a certain size after bonding, the optical fiber exposed from the end surface of the substrate is cut together with the base material. By laying the optical fiber, the flatness of the surface layer is lost and electrical wiring cannot be formed. No solutions have been reported for these problems. Therefore, an object of the present invention is to solve these problems and to provide an optoelectric composite substrate capable of high-density mounting of electrical and optical wirings, and a method of manufacturing the same.

[0007]

The present invention uses the following means in order to achieve the above object. Optical wiring is formed in the interlayer portion of the electric wiring board. As this means, for example, an optical fiber is used. This optical fiber is previously coated with a thermosetting resin. In order to wire an optical fiber, metal is etched into an optical wiring shape. At this time, if the gap between the conductor layers etched into the optical wiring shape is made narrower than the diameter of the optical fiber coated with the thermosetting resin, the optical fibers are pushed into the gap between the conductor layers and the conductor layers during wiring. If the gap between the conductor layers that are temporarily fixed and etched into the optical wiring shape is made wider than the diameter of the optical fiber coated with thermosetting resin, the optical fibers will be Temporary fixing is performed by partially welding the coated thermosetting resin. Further, a plurality of copper clad laminates for multilayer, on which optical wiring is formed by the above method, are bonded together with electric wiring by a prepreg. After bonding, in the outer shape cutting work to finish to a certain size, the optical fiber exposed from the substrate end surface is cut together with the base material, but by etching the thermosetting resin portion of the end surface of the multilayer board after bonding, Re-expose the end of the fiber core wire from the end face.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 11 are views showing an optoelectric composite substrate of the present invention and a method of manufacturing the same. In the figure, the opto-electric composite substrate is composed of multilayer copper clad laminates 1 and 4 and a prepreg 8. Multi-layered copper clad laminate 1,4
Copper foils 2, 3 and 5, 6 are formed on both front and back surfaces. An optical fiber groove is formed in the copper foil 2 of the substrate 1, and an optical fiber 7 is provided in the groove so as to be sandwiched between the substrate 1 and the prepreg 8. The optical fiber 7 is coated with a thermosetting resin, is temporarily fixed by being pushed into the groove, and is tightly fixed to the copper foil 2 of the substrate 1 by utilizing the property of the thermosetting resin. A hole 9 is formed in the optoelectric composite substrate, and copper plating 10 is formed on the surface of the hole. Reference numeral 11 is a conductor circuit pattern formed on the uppermost surface of the substrate.

The method of manufacturing the substrate will be described below. First, the multilayer copper clad laminates 1 and 4 shown in FIGS. 1 and 2 are prepared. Next, the following steps are performed. That is, copper is removed from the copper foils 2 and 5 of the multilayer copper clad laminates 1 and 4 into an optical wiring shape by a photoetching method or the like to form as shown in FIGS. The gap width between the copper formed in the optical wiring shape is adjusted to be narrower than the diameter of the optical fiber coated with the thermosetting resin. At the same time when the optical wiring is formed, the electric wiring may be formed on the copper foil 2 and the copper foil 5. The optical fiber 7 in which the copper is removed in the optical wiring shape and the thermosetting resin is coated is laid. The optical fiber 7 can be temporarily fixed by pushing it into the gap between the copper.
This is because the thermosetting resin coated on the optical fiber is in a semi-cured state and is viscous, so that it can be sufficiently adhered to copper by being pushed. As a result, the optical fiber does not move until the bonding is completed, and sufficient positional accuracy can be obtained. As shown in FIG. 5, using a prepreg 8, a multilayer copper clad laminate is laminated and bonded by a vacuum hot press or the like, and as shown in FIG.
It is formed as shown in FIG. At the time of stacking and bonding, the thermosetting resin coated on the optical fiber 7 is melted by heating and fills the gap between the optical fiber 7 and the copper foil 2 formed in the optical wiring shape, so that resin unfilling called stacking void occurs. Can be prevented. Of course, in order to increase the number of layers, three or more copper clad laminates for multilayer may be used to increase the number of layers. Also,
A structure may be used in which only the copper foil is used for the outermost layer and the prepreg is used for attachment. After the lamination and adhesion is completed, as shown in FIG. 8, an outer shape cutting operation for finishing to a certain size is performed. At this time, a part of the optical fiber 7 (shown in FIG. 7) exposed from the end face of the substrate along with the base material is cut, but is exposed again in the step described later. As shown in FIG. 9, in order to connect the front and back of the substrate, a hole 9 is made in a desired portion with an NC drill or the like. As shown in FIG. 10, a plating catalyst is applied to the surfaces of the holes 9 and the copper foils 6 and 3, and the copper plating 10 is applied by a known method. As shown in FIG. 11, the surface conductor circuit pattern 11 is formed. At this time, the thermosetting resin portion on the end face of the multilayer plate is etched to expose the end of the fiber core wire from the end face. 1 and 2 in the manufacturing process of the opto-electric composite substrate of FIG.
The copper clad laminate for multilayer shown in was prepared. A glass cloth-based epoxy resin copper clad laminate was used as the multilayer copper clad laminate. The thickness of the copper foil 2 was selected from 35 μm, 70 μm, and 105 μm. The optical fiber 7 has a diameter of 125 μm and is coated with a thermosetting epoxy resin to a thickness of 20 μm. The copper foil in FIG. 3 was removed by photoetching. The width of the gap between copper formed in the optical wiring shape is 130 μm, 1
Four types of 40 μm, 150 μm and 160 μm were selected. Next, the optical fiber 7 is laid while pushing it into the gap between the copper, and three 0.1 mm thick prepregs 8 are stacked,
It was laminated and adhered by a vacuum hot press. After that, the outer shape cutting,
Drilling, plating, and outer layer circuit formation were performed, and the thermosetting resin portion on the end face of the multilayer board was etched to expose the end of the fiber core wire from the end face. Under each condition, the misalignment of the wiring of the optical fiber, the resin non-filling called laminated void around the optical fiber, and the substrate surface unevenness due to the optical fiber embedding which affects the surface circuit formation quality were evaluated.
As a result, when the copper foil thickness is 70 μm, the gap width is 140 μm or more,
It is confirmed that good quality can be obtained when the gap width is 130 μm or more when the copper foil thickness is 105 μm, and FIGS. 12 to 17 are views showing another manufacturing method of the present invention. 12 to 17, the same parts as those in FIGS. 1 to 11 are designated by the same reference numerals. 12 and 1 in the process of manufacturing the optoelectronic composite substrate of FIG.
The multilayer copper clad laminate shown in 3 was prepared. A glass cloth-based epoxy resin copper clad laminate was used as the multilayer copper clad laminate. The thickness of the copper foil 9 is 35 μm, 70 μm, 105 μm
3 types were selected. The optical fiber 7 has a diameter of 125 μm and is coated with a thermosetting epoxy resin to a thickness of 20 μm. The copper foil removal in FIG. 14 uses a photo-etching method.
The gap width between copper formed in the optical wiring shape is 180 μm,
190μm, 200μm, 210μm, 220μm 5
I chose the type. Next, the optical fiber 7 was laid, and heat was applied to partially weld the coated thermosetting resin, three prepregs 8 having a thickness of 0.1 mm were stacked, and laminated and bonded by a vacuum hot press. Under each condition, the misalignment of the wiring of the optical fiber, the resin non-filling called laminated void around the optical fiber, and the substrate surface unevenness due to the optical fiber embedding which affects the surface circuit formation quality were evaluated. As a result, the copper foil thickness is 70 μm to 105 μm, and the gap width is 180
It was confirmed that good quality can be obtained when the thickness is at least μm.
In addition, when the gap width between copper formed in the optical wiring shape as shown in FIGS. 12 to 17 is adjusted to be wider than the diameter of the optical fiber coated with the thermosetting resin, the optical fiber 7
By partially welding the thermosetting resin covered in the wiring of, it is possible to temporarily fix, so until the adhesion is completed,
The optical fiber does not move, and sufficient positional accuracy can be obtained. Also, in the step of removing copper into the optical wiring shape,
The copper may be formed in a U-shape without completely removing the copper. Further, instead of the optical fiber, a cylindrical tube may be wired, and then the optical fiber may be passed through this tube. In this embodiment, a multilayer copper clad laminate using a copper foil for the conductor layer is given as an example, but any conductive metal foil may be used, such as aluminum or iron. In particular, by increasing the thickness of the conductor layer, there is no difference from the diameter of the optical fiber, so that no protrusion is generated on the surface layer due to the wiring of the optical fiber and the flatness can be maintained, so that the electric wiring of the surface layer can be formed. Further, as the base material constituting the insulating layer of the multilayer copper-clad laminate, glass woven cloth, glass non-woven cloth, etc. can be used, and as the thermosetting resin impregnated into the base material, epoxy resin type, phenol resin type , Polyimide resin type, etc. can be used. Furthermore, the prepreg is made by impregnating a glass fiber base material with an epoxy resin type, a phenol resin type, a polyimide resin type, etc. so that the resin is in a semi-cured state. It is desirable to use the same type of insulating layer as described above.

[0010]

As described above, according to the present invention, the density of optical wiring can be increased by forming the same optical wiring between the layers of the high-multilayer substrate.

Further, according to the manufacturing method of the present invention, it is possible to form the optical wiring in the interlayer portion of the printed wiring board substrate. As a result, it is not necessary to wire the optical fiber to the front and back of the printed wiring board, and the mounting area for electronic components can be expanded.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 2 is a cross-sectional view showing an example of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 3 is a cross-sectional view showing an embodiment of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 4 is a cross-sectional view showing an example of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 5 is a cross-sectional view showing an example of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 6 is a cross-sectional view showing one example of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 7 is a perspective view showing an embodiment of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 8 is a perspective view showing an embodiment of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 9 is a cross-sectional view showing an example of a method for manufacturing an optoelectric composite substrate of the present invention.

FIG. 10 is a cross-sectional view showing an embodiment of the optoelectronic composite substrate and the method for manufacturing the same according to the present invention.

FIG. 11 is a perspective view showing an embodiment of an optoelectric composite substrate and a method for manufacturing the same according to the present invention.

FIG. 12 is a cross-sectional view showing another embodiment of the method of manufacturing another optoelectric composite substrate of the present invention.

FIG. 13 is a cross-sectional view showing another embodiment of the method for manufacturing another optoelectric composite substrate of the present invention.

FIG. 14 is a cross-sectional view showing another embodiment of the method for manufacturing another optoelectric composite substrate of the present invention.

FIG. 15 is a cross-sectional view showing another embodiment of the method of manufacturing another optoelectric composite substrate of the present invention.

FIG. 16 is a cross-sectional view showing another embodiment of the method for manufacturing another optoelectric composite substrate of the present invention.

FIG. 17 is a cross-sectional view showing another embodiment of the optoelectric composite substrate and the manufacturing method thereof according to the present invention.

[Explanation of symbols]

1,4 Multilayer copper clad laminate insulation layer 2,3,5,6,9 copper foil 7 Optical fiber (thermosetting resin coating) 8 prepreg 9 holes 10 plating 11 Conductor circuit pattern

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naoki Nishimura             216 Totsuka Town, Totsuka Ward, Yokohama City, Kanagawa Prefecture             Ceremony Company Hitachi Ltd. Communication Division F-term (reference) 2H038 CA52                 5E338 AA03 CD40                 5E346 AA15 CC04 CC06 CC09 CC10                       CC32 CC34 DD02 DD32 EE01                       FF01 HH25

Claims (12)

[Claims] 1. An optoelectric composite substrate, wherein optical wiring is formed in an interlayer portion of a wiring substrate made of a multilayer copper clad laminated substrate. 2. An optoelectric composite substrate, wherein the optical wiring according to claim 1 is an optical fiber. 3. The optoelectric composite substrate according to claim 2, wherein the optical fiber is previously coated with a thermosetting resin. 4. The optoelectric composite substrate according to claim 3, wherein an etching groove for fixing the optical fiber is formed in a part of the copper conductor layer of the multilayer copper clad substrate, and the optical fiber is laid in the groove. An opto-electric composite substrate characterized by the above. 5. An optoelectric composite substrate according to claim 4, wherein the etched portion has a U-shaped cross section. 6. The optoelectric composite substrate according to claim 4 or 5, wherein a conductor layer etched into the shape of the optical wiring and a gap width between the conductor layers are narrower than a diameter of the optical fiber coated with a thermosetting resin. Opto-electric composite substrate. 7. The optoelectric composite substrate according to claim 4 or 5, wherein a conductor layer etched into the optical wiring shape and a gap width between the conductor layers are wider than a diameter of the optical fiber coated with a thermosetting resin. Opto-electric composite substrate. 8. The method for wiring an optical fiber of an optoelectric composite substrate according to claim 6, wherein the optical fiber is temporarily fixed by being pushed into a gap between the conductor layers. . 9. The optical / electrical composite substrate according to claim 7, wherein the thermosetting resin coated on the optical fiber is temporarily fixed by partially welding. Wiring method. 10. A method of manufacturing an optical / electrical wiring board, wherein electric wirings and optical wiring shapes are formed on a plurality of copper clad laminates for multilayer by etching, and then optical fibers are formed between the conductor layers formed in the optical wiring shape. Is wired, temporarily fixed, and the copper clad laminate for multilayer is adhered by a prepreg. 11. The method of manufacturing an optoelectric composite substrate according to claim 10, wherein the thermosetting resin portion of the end face of the multilayer board after adhesion is etched to expose the end of the fiber core wire from the end face. 12. The method of manufacturing an optoelectric composite substrate according to claim 10, wherein a cylindrical pipe is wired instead of the optical fiber, and the optical fiber is inserted into the pipe when necessary.