JP2001015889A - Manufacture of optical and electrical wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical and electrical wiring board where an optical wiring layer which is not affected by the rugged surface of an electrical wiring is formed on an electrical wiring board provided with an electrical wiring. SOLUTION: This manufacturing method comprises a first process where an optical wiring layer 5 with a core which serves as an optical wiring that transmits optical signals is formed on the flat surface of a first support board, a second process where the optical wiring layer is separated from the first support board and bonded to the flat surface of a second support board 6, a third process where a second adhesive agent 10 is applied on the surface of the board with the electrical wiring 8, a fourth process where the surface of the optical wiring layer bonded to the surface of the second support board is bonded to the second adhesive agent applied to the surface of the board with an electrical wiring, a fifth process where the second support board and the first adhesive agent are separated from the optical wiring layer, and a sixth process where pads and viaholes necessary for mounting optical parts and electrical parts are formed on the optical wiring layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical / electrical wiring board on which optical wiring and electric wiring are laminated.

[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.

In order to solve such a problem, a part of copper electric wiring 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. I have. This is because, in the case of an optical signal, generation of noise and electromagnetic waves can be suppressed.

[0004] From the viewpoint of high-density mounting or miniaturization, optical and optical wiring are stacked on the same substrate.
It is desirable to make an electrical wiring board. For example, as described in JP-A-3-29905, there has been proposed a substrate in which an optical fiber is fixed on an electric wiring substrate with an insulating film. However, when an optical fiber is used as the optical wiring, due to the limit of its flexibility, it cannot cope with an optical wiring having a complicated shape, and the degree of freedom in design is reduced.
There is a problem that it is impossible to cope with high-density wiring or downsizing of a substrate.

[0005] For this reason, several configurations of optical / electrical wiring boards using so-called optical waveguides have been proposed as optical wirings on electrical wiring boards. The configuration of the optical waveguide is such that a core layer through which an optical signal propagates is embedded in a clad layer that confine the optical signal to the core layer. The core pattern can be formed by forming a metal mask by a photolithography technique and performing dry etching, or, when the core material is provided with photosensitivity, exposing and developing. For this reason, since the optical wiring can be formed based on the pattern of the photomask, the degree of freedom of the design is increased. Also, transmission over a relatively short distance can be supported.

However, when an optical waveguide is formed as an optical wiring layer on an electric wiring substrate, the surface of the electric wiring substrate as a base of the optical wiring layer has very large irregularities due to the multilayered electric wiring. Is formed. For this reason, if the optical waveguide is formed directly on the surface, there is a problem that the propagation loss of the optical signal increases due to the unevenness.

In order to solve this problem, it has been proposed that the optical wiring layer be formed into a film shape and bonded to an electric wiring substrate with an adhesive. The purpose is to suppress the loss by bonding the optical wiring film with a laminator or the like so as to make the curvature of the undulation of the optical wiring as large as possible due to the unevenness of the base. However, in this case, the loss due to the unevenness cannot be completely reduced.

Further, when the optical wiring film is bonded by a laminator, the bonding accuracy with the electric wiring substrate is not high, so that the positional accuracy between the optical components such as the laser element and the light receiving element and the optical wiring is reduced, and the optical axis is reduced. Matching becomes difficult.

Further, a method has been proposed in which a smoothing layer is coated to such an extent that the unevenness of the electric wiring is filled, and the surface is polished and smoothed. However, this method is not practical because it has problems such as contamination due to generation of polishing debris and a problem in that the accuracy of polishing amount is not obtained when the substrate size is large.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the related art, and has an optical wiring layer which is not affected by the unevenness of the electric wiring, on the electric wiring of the substrate having the electric wiring. It is an object to provide an optical / electrical wiring board.

[0011]

In order to achieve the above object, the present invention comprises a substrate having an electric wiring and an optical wiring for transmitting an optical signal thereon. Forming an optical wiring layer having a core serving as an optical wiring for transmitting an optical signal on a smooth first support substrate; A step of peeling the wiring layer from the first support substrate and bonding the wiring layer to the smooth second support substrate using the first adhesive; and applying the second adhesive to the surface of the substrate having electric wiring A step of bonding the surface of the optical wiring layer bonded on the second support substrate to a second adhesive applied to the surface of the substrate having electrical wiring;
An optical / electrical wiring board, comprising: a step of removing the supporting substrate and the first adhesive; and a step of forming a pad and a via hole for mounting an optical component and an electrical component on the optical wiring layer. This is a method of manufacturing.

According to a second aspect of the present invention, there is provided the method for manufacturing an optical / electrical wiring board according to the first aspect, wherein a substrate having high transparency to visible light is used as the second smooth supporting substrate. Things.

According to a third aspect of the present invention, there is provided an optical / electrical wiring board including a substrate having an electric wiring and an optical wiring layer having a core serving as an optical wiring for transmitting an optical signal. A step of making an optical wiring layer having a core that is an optical wiring that propagates light on a supporting substrate that is smooth and highly transparent to visible light, and a step of applying an adhesive to the surface of the substrate having electric wiring Bonding the optical wiring layer formed on the support substrate to an adhesive applied to the surface of the substrate having electrical wiring, removing the support substrate on the optical wiring layer, and forming the optical component and the electrical component on the optical wiring layer. Forming a pad and a via hole for mounting an optical and electric wiring board.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an optical / electrical wiring board according to claim 1 of the present invention will be described with reference to FIGS.

FIG. 1 shows a method of manufacturing an optical wiring layer film. A thin film layer of Cr and Cu is sputtered as a release layer 3 on a silicon wafer as the first support substrate 1, and thereafter,
A Cu layer of about 1 μm was formed in a copper sulfate plating bath. On top of that, a polyimide OPI-N10
05 (produced by Hitachi Chemical Co., Ltd.)
It was imidized at 0 ° C. At this time, the film thickness was 15 μm (step (a)).

The first support substrate is not limited to a silicon wafer. Any material may be used as long as it has a smooth surface, a heat resistance of about 400 ° C., and a robust material.

As in the step (b), as the core layer 4, polyimide OPI-N1305 (manufactured by Hitachi Chemical Co., Ltd.)
Was similarly spin-coated and imidized at 350 ° C. At this time, the film thickness was 8 μm.

Al is deposited on the surface of the core layer, a predetermined pattern of a photoresist is formed, an etching process is performed,
An Al metal mask was formed. Further, the core layer was etched by reactive ion etching using oxygen gas, and the Al film was removed by etching to form an optical wiring (step (c)). At this time, at the same time as the optical wiring, an alignment mark (not shown) was formed for improving the bonding accuracy with the electric wiring substrate 8.

From above, OPI-N1 is used as a cladding layer.
005 is similarly coated and imidized. At this time, the thickness of the cladding layer is 15 μm on the core layer optical wiring.
(Step (d)).

The stripping layer 3 was dissolved and removed with a ferric chloride solution, and the optical wiring layer film 5 was stripped (step (e)).

FIG. 2 shows a step of bonding the optical wiring layer film to the electric wiring substrate. As a second support substrate 6, a glass substrate is coated with a first adhesive 7 to a thickness of 1 μm, and an optical wiring layer film is bonded with a laminator. The alignment between the glass substrate 6 and the optical wiring layer film 5 is unnecessary,
The laminator makes the surface of the optical wiring layer very smooth. Heat treatment or ultraviolet irradiation treatment is performed depending on the type of the adhesive (step (f)).

As the electric wiring board 8, a polyimide multilayer wiring board was used. An electric wiring 9 is formed on the outermost surface, and irregularities having a thickness difference of 18 μm are formed. The electric wiring layer is not limited to the polyimide multilayer wiring board, and may be a single-layer insulating substrate or a multilayer wiring board in which electric wiring and insulating layers are alternately laminated. 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.

On this electric wiring board, a second adhesive 10
A modified polyimide resin showing thermoplasticity was applied and dried so as to form about 20 μm on the electric wiring.

As the second adhesive, a thermoplastic adhesive is preferable. For example, ethylene-acrylate copolymer, styrene-poly (meth) acrylate, butyral resin, polyamide resin, modified polyimide resin and the like can be mentioned. Among these, in consideration of the solder heat resistance on the optical / electrical wiring board, preferably, the bonding temperature is from 250 ° C. to 300 ° C., and a modified polyimide resin is optimal.

Finally, the optical wiring layer is moved from the second support substrate to
Since it is necessary to remove the first adhesive together, it is necessary to design the first adhesive and the second adhesive so that the adhesive strength of the second adhesive is larger than that of the second adhesive.

As shown in step (g), the alignment mark (not shown) provided on the electric wiring substrate coated with the second adhesive 10 and the light adhered to the glass substrate as the second support substrate. The alignment marks provided on the wiring layer were aligned over the glass substrate, and the positions of both were determined.

The glass substrate and the optical wiring layer have high transparency to visible light, and the thickness of the first adhesive is sufficiently small. It is possible to see the alignment marks on the wiring board.

Next, a heat treatment was performed at 250 ° C. for 1 hour while applying pressure from above the second support substrate (step (h)). If necessary, the pressure can be reduced to effect the bonding. In addition, if the second adhesive is an electron beam curable or the like, bonding can be performed by irradiation of an electron beam or the like from the second support substrate.

As in the step (i), the second support substrate 6 was peeled off together with the first adhesive, and the bonding of the electric wiring substrate and the optical wiring layer film was completed. At this time, the optical wiring layer was bonded and fixed while maintaining the smoothness of the second support substrate without being affected by the unevenness of the underlying electric wiring substrate.

A pad for mounting an optical component or an electric component and a via hole for establishing electrical continuity with the electric wiring substrate are formed in the optical wiring layer bonded to the electric wiring substrate, and the optical / optical device according to the present invention is formed. FIG. 3 shows the steps required to complete the electric wiring board.

As shown in step (j), a hole for forming a via hole is formed using a laser with reference to an alignment mark (not shown) on the electric wiring board 8. Drilling methods include carbon dioxide laser and UV-YAG
Laser, excimer laser, dry etching such as reactive ion etching, or the like can be used. In this case, the underlying electric wiring 9 serves as a stopper for perforation.

Next, a metal thin film is formed in the order of Cr and Cu by sputtering (step (k)). Further, PMER (manufactured by Tokyo Ohka Kogyo Co., Ltd.)
0 μm is applied by a spin coater and dried at 90 ° C. An alignment mark (not shown) formed on an electric wiring substrate using a photomask having a predetermined pattern
Is exposed and developed with reference to an opening 13 for forming a via hole and an opening 14 for forming a pad.
Was prepared. Further, post-baking was performed at 110 ° C. (step (l)).

Using a metal thin film as a cathode, Cu
Plating was performed. The thickness of the plating was 10 μm, which is about the same as the thickness of the photoresist (step (m)).

Finally, the photoresist was removed with a dedicated stripper, and the metal thin film 11 was dissolved and removed with an etchant to form a via hole 15 and a pad 16. Thus, the optical / electrical wiring board according to the present invention was completed (step (n)).

Next, an embodiment of a method for manufacturing an optical / electrical wiring board according to claim 3 of the present invention will be described with reference to FIGS.

FIG. 4 shows a method of manufacturing the optical wiring layer. Cr, as a release layer 23 on a glass substrate as a support substrate 21,
A Cu thin film layer was sputtered, and then a Cu layer was formed to about 1 μm in a copper sulfate plating bath. An alignment mark (not shown) for positioning with the support substrate 21 was formed at a predetermined position on the metal thin film layer by a conventional photoetching method.

On top of that, polyimide OPI-N1005 (manufactured by Hitachi Chemical Co., Ltd.) was spin-coated as a cladding layer 22 and imidized at 350 ° C. At this time, the film thickness was 15 μm (step (o)).

The support substrate is not limited to a glass substrate, and may be any material having a smooth surface, heat resistance of about 400 ° C., robustness, and high transparency to visible light.

As in the step (p), as the core layer 24,
Polyimide OPI-N1305 (Hitachi Chemical Industry Co., Ltd.)
Was spin-coated in the same manner and imidized at 350 ° C. At this time, the film thickness was 8 μm.

Al is deposited on the surface of the core layer, a predetermined pattern of a photoresist is formed, and an etching process is performed.
An Al metal mask was formed. Furthermore, the core layer was etched by reactive ion etching using oxygen gas, and the Al film was removed by etching to form an optical wiring (step (q)).

From above, OPI-N1 was formed as a cladding layer.
005 was similarly coated and imidized to complete the optical wiring layer 25. At this time, the thickness of the clad layer was 15 μm on the core layer optical wiring (step (r)).

Next, a step of bonding the optical wiring layer to the electric wiring board is shown in FIG.

As the electric wiring board 27, a polyimide multilayer wiring board was used. An electric wiring 26 is formed on the outermost surface, and irregularities having a film thickness step of 18 μm are formed. Electric wiring layer is not limited to polyimide multilayer wiring board,
A single-layer insulating substrate or a multilayer wiring substrate in which electric wiring and insulating layers are alternately stacked may be used. 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.

A modified polyimide resin exhibiting thermoplasticity as the adhesive 28 was applied and dried on the electric wiring board so as to form about 20 μm on the electric wiring.

As the adhesive, a thermoplastic adhesive is preferable.
For example, ethylene-acrylate copolymer, styrene-poly (meth) acrylate, butyral resin, polyamide resin, modified polyimide resin and the like can be mentioned. Considering the solder heat resistance on the optical / electrical wiring board, it is preferable that the bonding temperature is 25%.
Those having a temperature of 0 ° C. to 300 ° C. are good, and a modified polyimide resin is optimal.

As shown in step (s), an alignment mark (not shown) provided on the electric wiring board coated with the adhesive 28 and an alignment mark provided on the glass substrate as the support substrate are placed across the glass substrate. Together, we decided both positions.

Since the support substrate and the optical wiring layer have high transparency to visible light, the alignment mark of the optical wiring layer and the alignment mark of the electric wiring substrate can be seen from the back surface of the support substrate.

Next, while pressing from above the glass substrate, 2
Heat treatment was performed at 50 ° C. for 1 hour (step (t)). If necessary, the pressure can be reduced to effect the bonding.
If the adhesive is an electron beam curable or the like, the bonding can be performed by irradiation with an electron beam or the like from the support substrate.

As in the step (u), with a ferric chloride solution,
The release layer 23 was dissolved and removed, and the support substrate 21 was peeled off, whereby the bonding of the electric wiring substrate and the optical wiring layer was completed. At this time, the optical wiring layer was bonded and fixed while maintaining the smoothness of the third support substrate without being affected by the unevenness of the underlying electric wiring substrate.

A pad for mounting an optical component or an electric component and a via hole for establishing electrical continuity with the electric wiring substrate are formed in the optical wiring layer bonded to the electric wiring substrate. The steps up to completion of the electric wiring board are the same as the steps (j) to (n) in FIG.

[0051]

As can be understood from the above description, the present invention has the following effects.

First, the optical wiring layer can be fixed to a smooth second support substrate or a supporting substrate, and can be bonded to the electric wiring substrate while keeping the optical wiring layer in a smooth state. Unaffected by irregularities on the electrical wiring layer surface,
The propagation loss of the optical signal can be kept very small.

Second, since the second support substrate or the support substrate uses a highly transparent material, it is possible to read the alignment mark between the electric wiring substrate and the optical wiring layer from the surface opposite to the bonding surface of the optical wiring layer. Bonding is performed with high accuracy because it is possible. As a result, the position between the optical wiring and the optical component mounting pad can be accurately determined.

[0054]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a step of forming an optical wiring layer in a method of manufacturing an optical / electrical wiring board according to the present invention.

FIG. 2 is an explanatory view showing a step of bonding an optical wiring layer film and an electric wiring board in the method for manufacturing an optical / electric wiring board of the present invention.

FIG. 3 is an explanatory view showing a step of forming a pad and a via hole in the method for manufacturing an optical / electrical wiring board according to the present invention.

FIG. 4 is an explanatory view showing a step of forming an optical wiring layer in the method for manufacturing an optical / electrical wiring board according to the present invention.

FIG. 5 is an explanatory view showing a step of bonding an optical wiring layer film and an electric wiring board in the method for manufacturing an optical / electric wiring board of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first support substrate 2 clad layer 3 release layer 4 core layer 5 optical wiring layer (film) 6 second support substrate 7 first adhesive 8 electrical wiring substrate 9 electrical wiring 10 second adhesive 11 via hole formation Hole for 12 Metal thin film 13 Photoresist 14 Photoresist opening 15 Photoresist opening 16 Via hole 17 Pad 21 Support substrate 22 Cladding layer 23 Release layer 24 Core layer 25 Optical wiring layer 26 Electrical wiring 27 Electrical wiring board 28 Adhesive

Claims (3)

[Claims] An optical / electrical wiring board comprising: a substrate having an electric wiring; and an optical wiring layer having a core serving as an optical wiring for transmitting an optical signal. Forming an optical wiring layer having a core formed on a smooth first support substrate; separating the optical wiring layer from the first support substrate; A step of adhering to the second support substrate, a step of applying a second adhesive to the surface of the substrate having electric wiring, and a step of applying electric wiring to the surface of the optical wiring layer adhered on the second support substrate. A step of adhering to the second adhesive applied to the substrate surface, a step of peeling off the second support substrate and the first adhesive on the optical wiring layer, and a step of mounting an optical component and an electric component on the optical wiring layer Forming a pad and a via hole for the semiconductor device. Manufacturing method of optical / electrical wiring board. 2. The method for manufacturing an optical / electrical wiring board according to claim 1, wherein a substrate having high transparency to visible light is used as the smooth second support substrate. 3. An optical / electrical wiring board comprising: a substrate having an electric wiring; and an optical wiring layer having a core serving as an optical wiring for transmitting an optical signal. A step of forming an optical wiring layer having a core having a smooth surface on a supporting substrate having high transparency to visible light; a step of applying an adhesive to the surface of the substrate having electric wiring; A step of bonding the optical wiring layer to a second adhesive applied to the surface of the substrate having the electrical wiring, a step of peeling off the support substrate on the optical wiring layer, and mounting the optical component and the electrical component on the optical wiring layer Forming a pad and a via hole for forming the optical / electrical wiring board.