JP4306011B2 - Optical wiring layer and manufacturing method thereof, optical / electrical wiring substrate, manufacturing method thereof, and mounting substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical wiring layer, a manufacturing method of the optical wiring layer, an optical / electrical wiring board in which optical wiring and electric wiring are mixed, a manufacturing method of the optical / electrical wiring board, and an optical component and an electric circuit on the optical / electrical wiring board. The present invention relates to a mounting board on which components are mounted.
[0002]
[Prior art]
In order to make a computer that can perform arithmetic processing faster, the clock frequency of the CPU tends to increase more and more, and now the one of the order of 1 GHz has appeared. As a result, there is a part where high-frequency current flows in the copper electrical wiring on the printed circuit board in the computer, so that malfunctions may occur due to the generation of noise, and electromagnetic waves may be generated, adversely affecting the surroundings. It will also be.
[0003]
In order to solve such a problem, a part of electric wiring made of copper on a printed board is replaced with an optical wiring made of an optical fiber or an optical waveguide, and an optical signal is used instead of an electric signal. This is because the generation of noise and electromagnetic waves can be suppressed in the case of optical signals.
[0004]
Incidentally, one method for optically coupling an optical component and an optical wiring is to provide a mirror in the optical wiring. FIG. 1 is a specific example described in Japanese Patent Laid-Open No. 5-241044. The laser beam 7 propagating through the optical waveguide 1 is reflected by the mirror 3 and enters the light receiving surface 5 of the light receiving element 4. However, since the laser beam 7 reflected by the mirror 3 spreads, there is a disadvantage that the optical coupling efficiency is deteriorated when the light receiving surface 5 is small. In order to solve this drawback, in the invention of Japanese Patent Laid-Open No. 5-241044, it is proposed to provide the convex lens 8 shown in FIG. is doing.
[0005]
However, in the method disclosed in Japanese Patent Laid-Open No. 5-241044, the optimum convex lens 8 changes depending on factors such as the relative positional relationship between the light receiving element 4 and the optical waveguide 1 or the size of the light receiving surface 5. When mounting these optical components, the convex lens 8 must be made according to the type of each optical component, which is complicated.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the related art, and manufactures an optical / electrical wiring board using an optical wiring layer having a structure in which optical coupling efficiency between an optical component and an optical wiring is good and easy to manufacture. It is an object to provide a method.
[0007]
The means provided by the present invention to achieve the above object is to manufacture an optical wiring layer having a core and a clad on a horizontal plane of a support having a horizontal plane, and to use the optical wiring layer to provide an optical / electrical wiring board. A method of manufacturing
In the case of manufacturing the optical wiring layer, light comprising a step of forming a release film on the horizontal surface of the support, and a first core and a clad extending on the release film in parallel to the horizontal surface of the support. A step of forming a wiring layer, a step of opening a hole perpendicular to the optical wiring layer in the optical wiring layer, a step of filling the hole with a core material to form a second core, a first core and a second core A step of forming a mirror having a mirror surface at an angle of 45 degrees with respect to the optical wiring layer at a portion where the core of the optical fiber intersects, a step of peeling the optical wiring layer from the support after forming the mirror, The optical wiring layer is manufactured by a process including:
Thereafter, the step of bonding the side surface on which the mirror of the optical wiring layer is formed to the electric wiring side of the substrate having the electric wiring, and the step of making a pad electrically connected to the electric wiring of the substrate by the via hole And a method for manufacturing an optical / electrical wiring board.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
1. Optical Wiring Layer FIG. 3 shows a cross-sectional view of the optical wiring layer of the present invention. The optical wiring layer includes a core 21 that propagates laser light in a direction parallel to the optical wiring layer, and a core 22 that propagates laser light in a direction perpendicular to the optical wiring layer. These cores are optical wirings and are surrounded by the clad 23. At a portion where the core 21 and the core 22 intersect, there is a mirror 24 having a mirror surface at an angle of 45 degrees with respect to the optical wiring layer. The mirror surface of the mirror 24 may be provided with a reflective layer made of a metal film 25 such as aluminum as shown in FIG.
[0018]
As shown in FIG. 5, the laser light 26 propagating through the core 21 is reflected by the mirror 24 and further propagates through the core 22. Even if the laser beam 26 spreads due to reflection by the mirror 24, it is confined in the core 22, and is emitted from the end of the core 22 as a thin beam.
[0019]
2. Manufacturing Method of Optical Wiring Layer The manufacturing method of the optical wiring layer includes a first embodiment in which a reflective layer made of a metal film is not provided on a mirror surface and a second embodiment in which a reflective layer made of a metal film is provided on a mirror surface. .
[0020]
<First Embodiment of Manufacturing Method of Optical Wiring Layer>
First, the first embodiment will be described according to the flow of FIGS.
[0021]
As shown in FIG. 6A, a release film 32 is formed on the support 31.
[0022]
As shown in FIG. 6B, an optical wiring layer including a core 33 and a clad 34 is formed on the release film 32 by using a photolithography technique.
[0023]
As shown in FIG. 6C, a hole 35 perpendicular to the optical wiring layer is opened by a laser.
[0024]
As shown in FIG. 6D, the hole 35 is filled with the same material as the core 33 to make the core 36.
[0025]
As shown in FIG. 6E, a groove 37 is formed by dicing at a portion where the core 33 and the core 36 intersect to form the mirror 37.
[0026]
By immersing the release film 32 in a release solution, the optical wiring layer is peeled off from the support 31 to obtain an optical wiring layer as shown in FIG.
[0027]
<Second Embodiment of Manufacturing Method of Optical Wiring Layer>
The second embodiment will be described in accordance with the flow of (a) to (e) in FIG.
[0028]
As shown in FIG. 7A, a release film 42 is formed on the support 41.
[0029]
As shown in FIG. 7B, an optical wiring layer composed of a core 43 and a clad 44 is formed on the release film 42 by using a photolithography technique.
[0030]
As shown in FIG. 7C, a hole 45 perpendicular to the optical wiring layer is opened by a laser.
[0031]
As shown in FIG. 7D, the hole 45 is filled with the same material as the core 43 to make the core 46.
[0032]
As shown in FIG. 7E, a film 47 is coated on the optical wiring layer. A resist may be used instead of the film.
[0033]
As shown in FIG. 7F, a groove 48 is formed in the optical wiring layer by dicing.
[0034]
As shown in FIG. 7G, the mirror 50 is formed by covering the optical wiring layer with a metal film 49 such as aluminum.
[0035]
The film 47 is peeled off, and the metal film 49 is peeled off except for the grooves 48. Further, the release film 42 is immersed in a release solution, and the optical wiring layer is peeled off from the support 41 to obtain an optical wiring layer as shown in FIG.
[0036]
3. Optical / Electrical Wiring Substrate The optical wiring layer of the present invention is bonded to the electric wiring 61 and 62 side of the substrate 60 via the absorption layer 67 on the mirror 24 side (see FIG. 8). When the optical wiring layer (see FIG. 6F) obtained by the first embodiment of the optical wiring layer manufacturing method is used, it may be adhered while the air is in contact with the end face of the core. Then, after filling the groove portion with a medium having a refractive index lower than that of the core, the end face of the core may be bonded in a state of being in contact with a medium having a refractive index smaller than that of the core. Furthermore, if the absorbing layer is flexible enough to fill the end face (groove portion) of the core and has a refractive index smaller than that of the core, it can be bonded together with filling.
As shown in FIG. 8, the optical / electrical wiring board of the present invention is further provided with pads 65 and 66 that are electrically connected to the electrical wiring 61 or 62 by via holes 63 or 64. Here, the pads 65 and 66 are for soldering optical components.
[0037]
FIG. 9 is a cross-sectional view when a lead of a laser light emitting element 71 such as a semiconductor laser is soldered on the pads 65 and 66. Laser light 75 emitted from the laser light emitting surface 72 of the laser light emitting element 71 propagates through the core 22, is reflected by the mirror 24, and then propagates through the core 21.
[0038]
FIG. 10 is a cross-sectional view when the lead of the light receiving element 81 such as a photodiode is soldered on the pads 65 and 66. The laser beam 85 propagating through the core 21 is reflected by the mirror 24, propagates through the core 22, and enters the light receiving surface 82 of the light receiving element 81. As described above, the laser beam 85 reflected by the mirror 24 spreads but is confined in the core 22, so that it is emitted as a thin beam from the end of the core 22 and efficiently enters the light receiving surface 82.
[0039]
The absorption layer 67 in FIG. 8 is for reducing the optical signal propagation loss of the cores 21 and 22 by absorbing the irregularities formed by the electrical wirings 61 and 62. For the absorption layer 67, a material having plasticity or elasticity or both is used. An absorption layer using a plastic material is called a smooth layer, and an absorption layer using an elastic material is called a cushion layer. Most preferably, the adhesive layer formed when the optical wiring layer is bonded to the substrate 60 using an adhesive having plasticity and elasticity also serves as the absorption layer.
[0040]
When a reflective layer made of a metal film is not provided on the mirror surface of the mirror 24, the mirror surfaces that are the end surfaces of the core 21 and the core 22 are in direct contact with the absorption layer 67. In this case, in order for the laser light to be totally reflected by the mirror 24, the refractive index of the absorption layer 67 must be smaller than the refractive index of the core.
[0041]
Pads for soldering electrical components may be provided on the optical wiring layer of the optical / electrical wiring board, or electrical wiring may be provided. The pad for the electrical component may be electrically connected to the wiring on the substrate by a via hole in the same manner as the pad for the optical component.
[0042]
When the electrical wiring is provided on the optical wiring layer, the pad may be connected only to the electrical wiring on the optical wiring layer and not to the electrical wiring on the substrate. In this case, of course, there is no via hole for electrically connecting the pad and the electric wiring on the substrate.
[0043]
4). Manufacturing Method of Optical / Electrical Wiring Substrate The manufacturing method of the optical / electrical wiring substrate of the present invention is focused on the pads for optical components that are electrically connected to the electric wiring on the substrate by via holes. The description will be made according to the flow (f).
[0044]
As shown in FIG. 11A, the mirror 91 side of the optical wiring layer 90 is bonded to the side having the electric wiring 93 of the substrate 92 through the absorption layer 94. The absorption layer 93 is formed on the substrate 92 and then bonded, or the absorption layer 94 is formed on the mirror 91 side of the optical wiring 90 and then bonded to the substrate 92. As described above, the absorbent layer 93 may be a smooth layer, a cushion layer, or a combination of both properties, but preferably by an adhesive that combines both properties. Good adhesion layer. In addition, as described above, when the mirror layer of the mirror 91 is not provided with a reflective layer made of a metal film and the absorbing layer is in contact with the mirror surface, the refractive index of the absorbing layer is made smaller than the refractive index of the core.
[0045]
As shown in FIG. 11B, a hole 95 for forming a via hole is opened by a laser. Next, although not shown, a chromium thin film is formed by sputtering on the surface of the hole 95 and the surface of the optical wiring layer 90 on the side opposite to the substrate 92, and then the same is formed on the chromium thin film by sputtering. A thin copper film is formed.
[0046]
As shown in FIG. 11C, a resist 96 is applied on the surface of the optical wiring layer 90.
[0047]
The resist 96 is exposed through a photomask, and then developed, and the resist 96 is removed only at a portion where a pad, an electric wiring, etc. are to be formed as shown in FIG.
[0048]
Further, copper is electroplated using the copper thin film formed on the surface of the hole 95 and the optical wiring layer 90 as an electrode, and as shown in FIG. 11 (e), the pad 100 for electric parts, the electric wiring 99, and the via hole. 98 and pads 97 for optical components are made.
[0049]
The resist 96 is removed. Thereafter, the chromium and copper thin films formed on the surface of the optical wiring layer 90 are removed by soft etching to obtain an optical / electrical wiring layer as shown in FIG.
[0050]
【The invention's effect】
As can be understood from the above description, the present invention has the following effects.
[0051]
First, since a thin beam laser is emitted from the core that propagates light perpendicular to the optical wiring layer, the light receiving element and the optical wiring can be efficiently optically coupled without a converging convex lens. effective. Therefore, it is not necessary to create a condensing convex lens according to factors such as the relative positional relationship between the light receiving element and the optical wiring, or the size of the light receiving surface of the light receiving element, and a condensing convex lens is used. Compared with the prior art, there is also an effect that the manufacture becomes easy.
[0052]
Second, the optical / electrical wiring board is provided with an optical wiring layer on the board having the electric wiring, so that there is an effect that high-density mounting or miniaturization is possible.
[0053]
Third, since the optical / electrical wiring board is provided with the electrical wiring also on the optical wiring layer, there is an effect that interference between the electrical wirings can be suppressed.
[0054]
Fourthly, according to the embodiment of the method for manufacturing an optical / electrical wiring board, by providing the absorbing layer, the absorbing layer absorbs the unevenness of the electric wiring on the board, so that there is no optical signal propagation loss. is there. Further, when the optical wiring layer is bonded to the substrate, there is also an effect that the bonding is very precisely matched with the one intended for the bonding.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating optical coupling of a light receiving element and an optical waveguide by a mirror.
FIG. 2 is a diagram for explaining how to improve the coupling efficiency between a light receiving element and an optical waveguide by a convex lens.
FIG. 3 is a cross-sectional view of an optical wiring layer of the present invention.
FIG. 4 is a cross-sectional view of an optical wiring layer in which a reflective layer made of a metal film is provided on a mirror.
FIG. 5 is a view for explaining propagation of laser light in an optical wiring layer.
FIG. 6 is a diagram illustrating a method for manufacturing an optical wiring layer.
FIG. 7 is a view for explaining a method of manufacturing an optical wiring layer when a reflective layer of a metal film is provided on a mirror.
FIG. 8 is a cross-sectional view of the optical / electrical wiring board of the present invention.
FIG. 9 is a view for explaining propagation of laser light when a laser light emitting element is mounted on the optical / electrical wiring board of the present invention.
FIG. 10 is a view for explaining propagation of laser light when a light receiving element is mounted on the optical / electrical wiring board of the present invention.
FIG. 11 is a diagram illustrating a method for manufacturing an optical / electrical wiring board according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical waveguide 2 ... Board | substrate 3 ... Mirror 4 ... Light receiving element 5 ... Light receiving surface 6 ... Solder bump 7 ... Laser beam 8 ... Convex lens 21 ... Core 22 ... Core 23 ... Cladding 24 ... Mirror 25 ... Metal film 26 ... Laser beam 31 ... support 32 ... peeling layer 33 ... core 34 ... cladding 35 ... hole 36 ... core 37 ... mirror 41 ... support 42 ... peeling layer 43 ... core 44 ... cladding 45 ... hole 46 ... core 47 ... film 48 ... groove 49 ... Metal film 50 ... Mirror 60 ... Substrate 61 ... Electric wiring 62 ... Electric wiring 63 ... Via hole 64 ... Via hole 65 ... Pad 66 ... Pad 67 ... Absorbing layer 71 ... Laser light emitting element 72 ... Laser light emitting surface 73 ... Lead 74 ... Solder 75 ... Laser beam 81 ... Light receiving element 82 ... Light receiving surface 83 ... Lead 84 ... Solder 85 ... Laser light 90 ... Optical wiring layer 91 ... Mirror 92 ... Substrate 93 ... Electric wiring 94 ... Absorbing layer 95 Pad holes 96 ... resist 97 ... pad 98 ... via hole 99 ... electric wiring 100 ... electric parts for optical parts

Claims (1)

A method of manufacturing an optical wiring layer having a core and a clad on a horizontal surface of a support having a horizontal surface, and manufacturing an optical / electrical wiring substrate using the optical wiring layer,
When manufacturing the optical wiring layer,
Forming a release film on the horizontal surface of the support;
Forming an optical wiring layer comprising a first core and a clad extending parallel to the horizontal surface of the support on the release film;
Opening a hole perpendicular to the optical wiring layer in the optical wiring layer;
Filling the hole with core material to make a second core;
Forming a mirror having a mirror surface at an angle of 45 degrees with respect to the optical wiring layer at a portion where the first core and the second core intersect;
After forming the mirror, peeling the optical wiring layer from the support;
The optical wiring layer is manufactured by a process including:
Thereafter, bonding the side surface of the optical wiring layer on which the mirror is formed to the electric wiring side of the substrate having the electric wiring;
Creating a pad electrically connected to the electrical wiring of the substrate by via holes;
A method of manufacturing an optical / electrical wiring board, comprising:

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