JP2001108853A - Optical wiring layer, opto-electric wiring board, and packaging substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an opto-electric wiring board which makes a higher-density packaging and downsizing possible and in which the packaging of optical parts can be executed by the same method as for packaging of electric parts. SOLUTION: The laminar optical wiring layer having a core 1 for propagating light and a clad 2, a mirror 3 which has an inclination to the core and reflects light and a light incident and exit part for incidence and emission of the light is larger in the maximum width of the effective region of the mirror by >=2 times the thickness of the core. Further, the core has a tapered shape of the sectional area increasing near the mirror and the mirror is a concave surface mirror.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical / electrical wiring board, an optical / electrical wiring board in which optical wiring and electric wiring are mixed, and a mounting substrate in which optical and electric components are mounted on the optical / electrical wiring board.

[0002]

2. Description of the Related Art In order to make a computer capable of performing arithmetic processing faster, the clock frequency of a CPU tends to increase more and more, and a clock frequency of the order of 1 GHz has come to the present. As a result, there is a portion where a high-frequency current flows in the electric wiring made of copper on the printed circuit board in the computer, so that malfunction occurs due to generation of noise, and electromagnetic waves are generated, which adversely affects 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 circuit board is replaced with an optical fiber or an optical waveguide, and an optical signal is used instead of an electric signal. Because, for optical signals,
This is because generation of noise and electromagnetic waves can be suppressed.

From the viewpoint of high-density mounting or miniaturization, it is desirable to manufacture an optical / electrical wiring board in which electric wiring and optical wiring are laminated on the same substrate. When mounting optical components such as laser light-emitting elements and light-receiving elements, it is difficult to optically match the optical axis of the optical component with the optical axis of the optical wiring. Did not. Therefore, there is a disadvantage that mounting an optical component on an optical / electrical wiring board is extremely expensive compared to an electrical component that can be automatically soldered in a reflow furnace or the like.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the state of the prior art, and enables high-density mounting or miniaturization, and the mounting of optical components in the same manner as the mounting of electrical components. An object of the present invention is to provide an optical / electrical wiring board that can be used.

[0006]

In order to achieve the above object, first, the present invention provides a core and a clad for transmitting light, and a mirror having a tilt with respect to the core and reflecting light. An optical wiring layer having a light input / output portion for inputting / outputting light, wherein the maximum width of the effective area of the mirror is at least twice as large as the thickness of the core. The invention according to claim 2 is based on the premise of the invention according to claim 1, wherein the core has a tapered shape whose cross-sectional area increases near the mirror. According to a third aspect of the present invention, based on the first and second aspects, the mirror is a concave mirror. The invention according to claim 4 is based on the inventions according to claims 1 to 3, wherein the light input / output unit is
An optical wiring layer characterized in that the optical wiring layer is not perpendicular to the incoming / outgoing light. The invention according to claim 5 is the invention according to claim 1.
5. A light beam obtained by laminating a substrate having an electric wiring on at least the side opposite to the light input / output portion of the optical wiring layer according to any one of the above-mentioned items.
An optical wiring board, comprising: a pad for soldering an optical component, and a via hole for electrically connecting the pad and an electric wiring of the substrate, around the light input / output section. It is an electric wiring board. According to a sixth aspect of the present invention, there is provided an optical / electrical wiring board in which a substrate having an electric wiring is laminated on at least the light incident / exit portion side of the optical wiring layer according to any one of the first to fourth aspects. And a hole for transmitting light from the optical component or to the optical component. According to a seventh aspect of the present invention, there is provided an optical / electrical wiring board based on the premise of the sixth aspect, further including a hole for installing an optical component. The invention according to claim 8 is
An optical / electrical wiring board according to any one of claims 5 to 7, wherein an optical component and / or an electrical component is mounted on the optical / electrical wiring board.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

[0008] 1. Optical Wiring Layer In the optical wiring layer of the present invention, a top view and a vertical cross-sectional view of a portion where light enters the optical wiring are shown in FIGS.

The optical wiring layer 4 of the present invention is an optical wiring layer for transmitting light, and includes a linear core 1 embedded in a layered cladding 2 and a mirror 3 tilted with respect to the core 1. Have. The core 1 has a higher refractive index than the cladding 2, and light mainly propagates through the core 1. Mirror 3
Is the size of the portion where the mirror 3 is in contact with the core 1.

The mirror 3 of the present invention is characterized in that the width of the mirror 3 is larger than the width of the normal portion of the core 1. Specifically, the maximum width of the effective area of the mirror 3 is at least twice as large as the thickness of the normal portion of the core 1. When the mirror 3 is twice or more larger, the incident portion becomes larger, and the alignment of the optical component becomes easier. Here, the maximum width is the maximum value of the distance between two points in the effective area of the mirror 3, and becomes a diagonal line when the mirror 3 is rectangular as shown in FIG. Further, the mirror 3 is not limited to a mirror using a metal, but it is preferable to use a metal since the reflectance and the mechanical strength can be maintained. Note that the size of the mirror 3 is
Larger is better, but in view of noise generation,
It is preferred to be 20 times or less.

The connecting portion between the small core 1 and the large mirror 3 has a tapered shape such that the diameter of the core 1 increases near the mirror 3. As a result, light can be smoothly transmitted to the core 1
Go inside.

In the example shown in FIG. 1, since the angle between the direction of the core 1 and the normal line of the mirror 3 is larger than 45 degrees, the mirror size in the direction parallel to the core is increased, and the width of the core is tapered. By making the shape, the mirror size in the direction perpendicular to the core is increased.

In the example shown in FIG. 2, the angle between the direction of the core 1 and the normal line of the mirror 3 is approximately 45 degrees. However, by making both the width and thickness of the core 1 tapered, the mirror size can be reduced. I'm making it big.

In the example shown in FIG. 3, the mirror 3 is a concave mirror in the direction perpendicular to the width of the core 1, and the light is converged to increase the probability of entering the core 1.

In the example of FIG. 4, the mirror 3 is a concave mirror in both the width direction and the direction perpendicular to the width of the core 1,
Further, the light is converged to increase the probability of entering the core 1.

In the examples of FIGS. 2 to 4, the light incident portion is not a plane perpendicular to the incident light (a plane parallel to the optical wiring layer). Thereby, the phenomenon that the reflected light returns to the light emitting element and makes the operation unstable can be avoided.

It is to be noted that all the light input / output portions on the optical wiring layer are not limited to the structures of the present invention. It is desirable to use the structure of the present invention in combination with another structure as necessary. For example, the structure of the present invention can be used for the light incident portion, and the conventional structure (see FIG. 15) can be used for the light emitting portion.

2. Manufacturing of Optical Wiring Layer In manufacturing the optical wiring layer of the present invention, a first embodiment in which only the width direction of the core 1 is tapered and a second embodiment in which both the width and the thickness of the core 1 are tapered. Of the embodiment.

<First Embodiment of Manufacturing Optical Wiring Layer> First, a first embodiment will be described with reference to the flow charts of FIGS.

As shown in FIG. 5A, a release layer 6 is formed on a support 5.

As shown in FIG. 5B, an optical wiring layer including a core 1 and a clad 2 is formed on the release film 6. At this time, a photolithography technique or a dry etching technique is preferably used. The width of the core 1 near the mirror 3 is tapered.

As shown in FIG. 5C, a mirror 3 is formed by a dicing saw. At that time, mirror 3
A blade is used such that the angle formed by the normal line of the portion and the direction of the core 1 is larger than 45 degrees.

As shown in FIG. 5D, a metal film 3A made of aluminum or the like is formed on a portion to be the mirror 3. At that time, a photolithography technique or a mask deposition technique is suitably used.

As shown in FIG. 5E, a protective layer 2A is formed. The protective layer 2A may be made of the same material as the clad 2, or may be made of a different material.

By peeling from the release layer 6, the optical wiring layer 4 as shown in FIG. At this time, a method of dipping in a stripping solution or performing heat treatment is suitable.

The thickness of the core of this embodiment is 10
μm, and the maximum width of the effective area of the mirror was 30 μm.

<Second Embodiment of Manufacturing Optical Wiring Layer> Second Embodiment
Will be described in accordance with the flow of FIGS. 6 (a) to 6 (h).

As shown in FIG. 6A, a release layer 6 is formed on a support 5.

As shown in FIG. 6B, the clad 2 is formed on the release film 6.

As shown in FIG. 6C, a portion that becomes a tapered shape in the thickness direction of the core 1 and a portion that becomes the mirror 3 are formed by a dicing saw. At this time, if the section of the blade serving as the mirror 3 has a straight section, a plane mirror is formed, and if the section is curved, a concave mirror is formed in a direction perpendicular to the width of the core 1.

Further, as shown in FIG. 6D, if a portion to be the mirror 3 is additionally processed by a diamond drill, a concave mirror in the width direction of the core 1 and the direction perpendicular to the width is formed.

As shown in FIG. 6E, a metal film 3A made of aluminum or the like is formed on a portion to be the mirror 3. At that time, a photolithography technique or a mask deposition technique is suitably used.

The core 1 is formed as shown in FIG. At this time, a photolithography technique or a dry etching technique is preferably used. The width of the core 1 near the mirror 3 is tapered.

As shown in FIG. 6G, the clad 2 is formed.

By peeling off from the peeling layer 6, the optical wiring layer 4 as shown in FIG. At this time, a method of dipping in a stripping solution or performing heat treatment is suitable.

The thickness of the core of this embodiment is 50
μm, and the maximum width of the effective area of the mirror was 100 μm.

3. Optical / Electrical Wiring Board The optical wiring layer of the present invention has a first embodiment in which an electrical wiring board is bonded to at least the opposite side of the light input / output section, and a second embodiment in which the electrical wiring board is bonded to at least the light input / output section. There are two embodiments.

<First Embodiment of Optical / Electrical Wiring Substrate> An absorbing layer 7 is provided at least on the opposite side of the optical input / output portion of the optical wiring layer 4.
The electric wiring board 10 is adhered through the substrate (see FIG. 7). Further, the electric wiring 1 is formed by the via holes 11 or 12.
Pads 15 and 16 electrically connected to 3 or 14 are provided. Here, the pads 15 and 16 are for soldering an optical component. Beer hole 11
And 12 also have the effect of preventing displacement between the optical wiring layer and the electric wiring board.

The electric wiring substrate 10 may be a single-layer insulating substrate or a multilayer wiring board in which electric wiring and insulating layers are alternately laminated. Further, as a constituent material, an insulating substrate in which a glass cloth is impregnated with a resin, a polyimide film, or a ceramic substrate may be used.

FIG. 8 is a sectional view when the leads of the laser light emitting element 20 such as a semiconductor laser are soldered on the pads 15 and 16. The laser light 22 emitted from the laser light emitting surface 21 of the laser light emitting element 20 propagates through the core 1 after being reflected by the mirror 3.

The absorption layer 7 shown in FIG.
This is for reducing the optical signal propagation loss of the core 1 by absorbing the unevenness formed by the core 1. The absorbing layer 7 is made of a material having plasticity, elasticity, or both.
An absorption layer using a plastic substance is called a smooth layer, and an absorption layer using an elastic substance is called a cushion layer. The most preferable case is that an adhesive layer formed when the substrate 10 is bonded to the optical wiring layer using an adhesive having plasticity and elasticity also serves as an absorption layer.

A pad for soldering an electric component may be provided on the optical wiring layer of the optical / electrical wiring board,
Further, electric wiring may be provided. Pads for electrical components
Similarly to the pad for the optical component, the via hole may be used to electrically connect to the wiring on the substrate.

When an electric wiring layer is provided on the optical wiring layer,
The pad may be connected only to the electric wiring on the optical wiring layer and not connected to the electric wiring on the substrate.
In this case, of course, there is no via hole for connecting the pad and the electric wiring on the electric wiring board.

The electric wiring substrate 30 may be a single-layer insulating substrate or a multilayer wiring board in which electric wiring and insulating layers are alternately laminated. Further, as a constituent material, an insulating substrate in which a glass cloth is impregnated with a resin, a polyimide film, or a ceramic substrate may be used.

<Second Embodiment of Optical / Electrical Wiring Board> The electrical wiring board 30 is adhered via the absorption layer 7 to at least the light incident / exit portion side of the optical wiring layer 4. Electric wiring board 30
Has a hole 31 for transmitting light from or to the optical component (see FIG. 9). Alternatively, the electric wiring board 30 has a hole 32 for installing an optical component (FIG. 1).
1).

FIG. 10 shows a laser light emitting device 40 such as a semiconductor laser on pads 33 and 34 on an electric wiring board.
FIG. 4 is a cross-sectional view when the lead is soldered. The laser light 42 emitted from the laser light emitting surface 41 of the laser light emitting element 40 passes through the hole 31, is reflected by the mirror 3, and propagates through the core 1.

FIG. 12 shows a laser light emitting device 40 such as a semiconductor laser on pads 33 and 34 on an electric wiring board.
FIG. 4 is a cross-sectional view when the lead is soldered. The laser light emitting element is housed inside the installation hole 32. The laser light 42 emitted from the laser light emitting surface 41 of the laser light emitting element 40 propagates through the core 1 after being reflected by the mirror 3.

The absorbing layer 7 shown in FIGS. 9 and 11 is for reducing the optical signal propagation loss of the core 1 by absorbing irregularities formed by electric wiring (not shown). The absorbing layer 7 is made of a material having plasticity, elasticity, or both. An absorption layer using a plastic substance is called a smooth layer, and an absorption layer using an elastic substance is called a cushion layer. Most preferably, an adhesive layer formed when the substrate 30 is adhered to the optical wiring layer using an adhesive having plasticity and elasticity also serves as an absorption layer.

A pad for soldering an electric component may be provided on the optical wiring layer of the optical / electrical wiring board.
Further, electric wiring may be provided. Pads for electrical components
The via hole may be electrically connected to the wiring on the substrate.

When an electric wiring layer is provided on the optical wiring layer,
The pad may be connected only to the electric wiring on the optical wiring layer and not connected to the electric wiring on the substrate.
In this case, of course, there is no via hole for connecting the pad and the electric wiring on the electric wiring board.

4. Method of Manufacturing Optical / Electrical Wiring Board The method of manufacturing an optical / electrical wiring board of the present invention focuses on pads that are electrically connected to electrical wiring on the substrate by via holes, and FIG. ) Will be described.

As shown in FIG. 13 or 14 (a), the absorption layer 7 is interposed on the optical wiring layer 4 on the side opposite to the light input / output section (see FIG. 13) or on the light input / output section side (see FIG. 14). Then, the substrate 50 is bonded. The absorption layer 7 is formed on the substrate 50 and then bonded, or the absorption layer 7 is formed on the optical wiring 4 and then the substrate 50 is bonded. As described above, the absorbing layer 7 may be a smooth layer, may be a cushion layer, or may have both properties, but is preferably made of an adhesive having both properties. Good adhesion.

As shown in FIG. 13 or FIG. 14B, a hole 51 for forming a via hole is opened by a laser. Next, although not shown, a chromium thin film is formed on the surface of the hole 51 and the surface of the optical wiring layer 4 on the side opposite to the substrate 50 by sputtering. A copper thin film is formed.

As shown in FIG. 13 or 14 (c), a resist 52 is applied to the surface of the optical wiring layer 4.

The resist 52 is exposed through a photomask and then developed to remove the resist 52 only at the portions where pads, electrical wiring, etc. are to be formed, as shown in FIG.

Further, copper is electroplated using the copper thin film formed on the hole 51 and the surface of the optical wiring layer 4 as an electrode.
As shown in FIG. 13 or 14 (e), a pad 53 for an electric component, an electric wiring 54, a via hole 55, and a pad 56 for an optical component are formed.

The resist 52 is removed. Thereafter, the thin film of chromium and copper formed on the surface of the optical wiring layer 4 is removed by soft etching to obtain an optical / electrical wiring board as shown in FIG.

5. Manufacturing Method of Mounting Board A light emitting element and a light receiving element, which are optical components, were mounted on the optical / electrical wiring board thus obtained without performing strict alignment, and a mounting board was manufactured. However, the mounting substrate showed sufficiently satisfactory characteristics.

6. Comparative Example A conventional structure (see FIG. 15) was formed by the same method as that of the first embodiment of manufacturing the optical wiring layer. That is, the thickness of the core is 10 μm, and the maximum width of the effective area of the mirror is 1
7 μm. Then, an optical / electrical wiring board was manufactured.

A strict positioning was not performed on the optical / electrical wiring board thus obtained, and a mounting board on which a light receiving element and a light emitting element were mounted was manufactured and its characteristics were examined. Did not.

[0061]

As can be understood from the above description, the present invention has the following effects. First, since the size of the mirror to be incident on the optical wiring layer is increased, the margin of the installation position of the light emitting element is increased, and there is an effect that strict alignment with the optical wiring becomes unnecessary. Therefore, mounting of components becomes easy.

Second, since the core in the vicinity of the mirror is tapered, light loss can be suppressed to a small value.

Third, since the mirror is a concave mirror, light loss can be further reduced.

Fourth, since the light input / output portion is not a horizontal surface, it is possible to avoid a phenomenon that reflected light returns to the light emitting element and makes the operation unstable.

Fifth, since the optical / electrical wiring board is provided with the optical wiring layer on the substrate having the electric wiring, there is an effect that high-density mounting or miniaturization is possible.

Sixth, the optical / electrical wiring board has the effect of suppressing the generation of noise and electromagnetic waves by using optical wiring.

[0067]

[Brief description of the drawings]

FIG. 1 is a top view and a longitudinal sectional view showing an example of an optical wiring layer of the present invention.

FIG. 2 is a top view and a longitudinal sectional view showing another example of the optical wiring layer of the present invention.

FIG. 3 is a top view and a longitudinal sectional view showing another example of the optical wiring layer of the present invention.

FIG. 4 is a top view and a longitudinal sectional view showing another example of the optical wiring layer of the present invention.

FIG. 5 is a diagram illustrating an example of a method for manufacturing an optical wiring layer according to the present invention.

FIG. 6 is an explanatory view of another example of the method for manufacturing an optical wiring layer of the present invention.

FIG. 7 is a sectional view showing an example of the optical / electrical wiring board of the present invention.

FIG. 8 is an explanatory diagram of laser light propagation when a laser light emitting element is mounted on the optical / electrical wiring board of the present invention.

FIG. 9 is a sectional view showing another example of the optical / electrical wiring board of the present invention.

FIG. 10 is an explanatory diagram of laser light propagation when a laser light emitting element is mounted on the optical / electrical wiring board of the present invention.

FIG. 11 is a sectional view showing another example of the optical / electrical wiring board of the present invention.

FIG. 12 is an explanatory diagram of propagation of laser light when a laser light emitting element is mounted on the optical / electrical wiring board of the present invention.

FIG. 13 is a diagram illustrating an example of the method for manufacturing an optical / electrical wiring board according to the present invention.

FIG. 14 is an explanatory view of another example of the method for manufacturing an optical / electrical wiring board according to the present invention.

FIG. 15 is a top view and a longitudinal sectional view showing a conventional optical wiring layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Core 2 ... Cladding 2A ... Protective layer 3 ... Mirror 3A ... Metal film 4 ... Optical wiring layer 5 ... Support 6 ... Release film 7 ... Absorption layer 10 ... Electric wiring board 11 ... Via hole 12 ... Via hole 13 ... Electric wiring 14 ... Electrical wiring 15 ... Pad 16 ... Pad 20 ... Laser light emitting element 21 ... Light emitting surface 22 ... Laser light 30 ... Electrical wiring board 31 ... Light transmitting hole 32 ... Parts installation hole 33 ... Pad 34 ... Pad 40 ... Laser light emitting element 41 ... Light-emitting surface 42 Laser light 50 Electric wiring board 51 Hole 52 Resist 53 Pad 54 Electric wiring 55 Via hole 56 Pad

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Ichikawa, Inventor F-term (reference), 1-5-1, Taito, Taito-ku, Tokyo 2H047 KA04 KA13 KA15 LA09 MA07 PA21 PA24 RA00 TA00 TA05 TA35 TA43 5E338 AA00 BB75 CC01 CC10 CD33 EE22 EE32

Claims (8)

[Claims] 1. A layered optical wiring layer having a core and a clad for transmitting light, a mirror having an inclination with respect to the core and reflecting light, and a light input / output unit for inputting / outputting light. The maximum width of the effective area of the core is larger than the thickness of the core by 2
An optical wiring layer characterized by being at least twice as large. 2. The optical wiring layer according to claim 1, wherein the core has a tapered shape whose cross-sectional area increases near the mirror. 3. The optical wiring layer according to claim 1, wherein said mirror is a concave mirror. 4. The optical wiring layer according to claim 1, wherein said light incident / exit portion is not perpendicular to the incident / exit light. 5. An optical / electrical wiring board in which a substrate having an electric wiring is laminated at least on the opposite side of the light input / output section of the optical wiring layer according to claim 1. An optical / electrical wiring board, comprising: a pad for soldering an optical component; and a via hole for electrically connecting the pad and an electric wiring of the board, around an input / output section. 6. An optical / electrical wiring board comprising a substrate having electric wiring laminated on at least the light incident / exit portion side of the optical wiring layer according to claim 1. An optical / electrical wiring board comprising: a hole for transmitting light to an optical component or an optical component. 7. The optical / electrical wiring board according to claim 6, further comprising: a hole for installing an optical component. 8. A mounting board, wherein an optical component and / or an electrical component is mounted on the optical / electrical wiring board according to claim 5.