JP2003287637A - Printed board with optical waveguide and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed board with an optical waveguide which is constituted by sticking an electric wiring board and a waveguide substrate without optically closing a through hole nor flawing an optical path conversion part and can prevent transmission loss from increasing and has high reliability. <P>SOLUTION: As for the printed board with the optical waveguide which is constituted by sticking with an adhesive the waveguide substrate 20 having an optical waveguide 2 where a reflecting surface 11 for converting an optical path is formed at an end part and the electric wiring board 10 which has the through hole 3 formed at the position of the reflecting surface 11 and passing light propagated in the optical waveguide 2 and is mounted with an optical element sending and receiving the light propagated in the optical waveguide 2 through the through hole 3 and the method for manufacturing the same, the through hole 3 is filled with transparent resin 13. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board used in a communication system and a method for manufacturing the same, and more particularly to an optical waveguide in which an electric wiring board for transmitting electric signals and a waveguide board for transmitting optical signals are laminated. And a method for manufacturing the same.

[0002]

2. Description of the Related Art In a conventional printed circuit board, signals are transmitted and received entirely by electricity. However, due to the limitation of electric transmission speed, there has been proposed a method in which light is used for high speed transmission and reception. (JP 2000-332301 A, etc.).

FIG. 6 shows a sectional view of a waveguide element using a printed circuit board with an optical waveguide in which an optical waveguide and an electric wiring are mixed.

As shown in FIG. 6, a waveguide device using a printed circuit board with an optical waveguide has a number of signals to be transmitted to an electric wiring board 10 on which a pattern of electric wiring 1 for transmitting electric signals is formed. As a portion for transmitting a high-speed signal of Gbps or higher, a waveguide substrate 20 on which an optical waveguide 2 for transmitting an optical signal is formed is laminated with an adhesive layer 6 interposed therebetween.
Further, another electric wiring board 9 is similarly laminated on the other surface of the waveguide substrate 20 with the adhesive layer 6 interposed therebetween.

The electrical wiring 1 and the optical waveguide 2 are connected by a through hole 3, and the optical waveguide 2 and the through hole 3 are connected.
An optical path conversion unit that converts the optical path of the optical signal is formed at the intersection of and, and above the optical path conversion unit,
LD (laser diode) 4 for converting electric-optical signals,
A PD (photodiode) 5 for converting an optical signal to an electric signal is provided, and the electric wiring 1 and the optical waveguide 2 are connected to each other.

The LD (4) and the PD (5) are respectively provided on the LD main body and the PD main body provided on the electric wiring 1 of the printed circuit board with the optical waveguide, and the electric wiring 1 and the LD (4) are provided. And PD (5) are provided with an LD driver 8 and a PD driver 7 for connecting them.

The electric signal i input from the electric wiring 1 is converted into an optical signal by the LD (4), is incident on the optical waveguide 2 from the optical path conversion unit on the input side, is transmitted, and then is output. Is emitted from the optical path conversion unit of the optical path conversion unit, converted into an electric signal by the PD (5), transmitted to another electric wiring board 9, and output from the electric wiring of the electric wiring board 9 as an electric signal o to the outside. ing.

A resin material such as polyimide or epoxy is used as a material for the printed circuit board with the optical waveguide,
In addition, as a pattern forming method of the optical waveguide 2, photolithography by a mask and UV exposure, RIE (Reac
tive Ion Etching), a molding method using a mold or the like is used.

Further, as described above, a 90 ° optical path changing section is necessary for optically coupling the LD (4) to the optical waveguide 2 and the optical waveguide 2 to the PD (5). A 45 ° mirror 11 formed by cutting out a groove in the optical waveguide 2 is used for the optical path changing unit.

A general method of forming the 45 ° mirror 11 will be described with reference to FIG.

As shown in FIG. 7, when the 45 ° mirror 11 is formed, the printed circuit board 20 with the optical waveguide is placed on the cutting plate P, and the optical waveguide is formed by using a dicer used for dividing the semiconductor into individual pieces. A cutting groove is formed in 2.

[0012] Specifically, the cutting blade C having a V-shaped cross section with a cutting edge of 45 ° is rotated to run while intersecting with the optical waveguide 2, so that the cutting edge of the cutting blade C is cut. The shape is transferred onto the optical waveguide 2, and the cut groove to be the 45 ° mirror 11 is processed.

[0013]

However, in the conventional printed circuit board with an optical waveguide, as shown in FIG. 5, after the through hole 3 serving as an optical path is formed in the electric wiring board 10, the printed wiring board with the electric wiring board 10 is formed. Since the waveguide substrate 20 and the waveguide substrate 20 are bonded to each other with the adhesive 6, the adhesive 6 may squeeze out and block the through-holes 3, resulting in failure of signal transmission. That is, since the diameter of the through hole 3 is very narrow, 0.1 mm or less, even a slight amount of adhesive squeeze-out is not allowed, which is difficult in terms of process.

Therefore, it is conceivable to form the through hole 3 with a laser after the electric wiring substrate 10 and the waveguide substrate 20 are bonded together, but a trace of the laser processing is left on the optical waveguide 2 and the transmission is left. The loss will increase.

Therefore, an object of the present invention is to reliably bond an electric wiring substrate and a waveguide substrate together without optically blocking the through hole and without damaging the optical path conversion portion, and thus preventing an increase in transmission loss. (EN) Provided is a printed circuit board with a high optical waveguide and a method for manufacturing the same.

[0016]

In order to solve the above-mentioned problems, the invention of claim 1 provides a waveguide substrate having an optical waveguide having a reflecting surface for changing the optical path at an end thereof, and the reflecting surface. An electric wiring board, which is formed at a position and has a through hole for transmitting light propagating through the optical waveguide, and on which an optical element for transmitting and receiving light propagating through the optical waveguide through the through hole is mounted, is bonded with an adhesive. In the printed circuit board with an optical waveguide, a transparent resin plug is formed by filling the through hole with a transparent resin.

According to a second aspect of the present invention, the adhesive is made of the same transparent resin as the transparent resin plug.

According to a third aspect of the present invention, an optical signal is transmitted / received between the waveguide substrate having the optical waveguide and a through hole formed in a direction intersecting with the optical waveguide and through the through hole. In the method for manufacturing a printed wiring board with an optical waveguide, in which an optical wiring and an electric wiring board to be connected to the optical element are bonded together, the through hole is filled with a transparent resin, and the waveguide board and the electric wiring board are provided. After bonding with a transparent resin, in order to optically couple the through hole and the optical waveguide, at the intersection of the through hole and the optical waveguide, with respect to the optical axis of the optical waveguide by cutting means. It is a method of forming a reflecting surface for changing the optical path by cutting diagonally.

According to a fourth aspect of the present invention, an optical signal is transmitted / received between the waveguide substrate having the optical waveguide and a through hole formed in a direction intersecting with the optical waveguide and through the through hole. In the method for manufacturing a printed wiring board with an optical waveguide, in which an electric wiring board on which an electrical wiring connected to an optical element is formed is attached, in order to optically couple the through hole and the optical waveguide, the through hole and At the intersection of the optical waveguide, by cutting obliquely with respect to the optical axis of the optical waveguide by a cutting means, after forming a reflection surface for optical path conversion, while filling the through hole with a transparent resin,
The waveguide substrate and the electric wiring substrate are attached with a transparent resin.

According to the above structure, since the through hole is filled with the transparent resin, the adhesive does not enter the through hole when the electric wiring substrate and the waveguide substrate are bonded together.

Furthermore, since the same adhesive as the transparent resin with which the through holes are filled is used as the adhesive, workability is improved.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of a printed circuit board with an optical waveguide according to the present invention.

As shown in FIG. 1, the printed circuit board with an optical waveguide according to the present invention transmits and receives optical signals to and from the optical waveguide 2 on one surface of the waveguide substrate 20 on which the optical waveguide 2 is formed. The electrical wiring substrate 10 on which the electrical wiring 1 to which the optical element is connected is formed by sandwiching the transparent resin layer 12 therebetween, and the electrical wiring for connecting to an external circuit is formed on the other surface. The wiring board 9 is formed by bonding with an adhesive.

The electric wiring board 10 has a through hole 3 which serves as an optical path converted by the optical path conversion section, and transmits and receives an optical signal to and from the optical waveguide 2 of the waveguide board 20 through the through hole 3. Has become. Furthermore, in this through hole 3,
A transparent resin plug 13 is formed by filling the same transparent resin as the transparent resin layer 12 formed between the electric wiring substrate 10 and the waveguide substrate 20.

The waveguide substrate 20 is formed with the optical waveguide 2 having an optical path converting portion at its end. This optical path changing unit
A 45 ° mirror 11 inclined at 45 ° is formed on the end face so as to convert the optical path by 90 °.

In this printed circuit board with an optical waveguide, since the 45 ° mirror is formed after the electrical wiring board 10 and the waveguide board 20 are bonded together, the transparent resin plug 1
Although the cut groove 13g is formed in 3, the transmission loss is not increased because it does not intersect the optical path.

Next, a method of manufacturing the printed circuit board with the optical waveguide will be described.

First, an electric wiring board 10 having electric wiring formed on its surface as shown in FIG. 4 (a) is prepared.
As shown in (b), the through hole 3 is formed at a predetermined position of the electric wiring board 10. Next, as shown in FIG. 4C, the through hole 3 is filled with a transparent resin, and the transparent resin plug 13
A transparent resin coating film (transparent resin layer 12) is formed on the side to which the waveguide substrate is attached for the purpose of flattening, and the optical waveguide 2 is formed as shown in FIG. 4 (d). The waveguide substrate 20 is attached. Then, as shown in FIG. 4E, a 45 ° mirror 11 is formed by a cutter blade in a portion of the optical waveguide 2 where 90 ° optical path conversion is required. Finally, as shown in FIG. 4F, another printed board 9 serving as an outer layer is laminated on the other surface of the waveguide board 20 by using an adhesive to manufacture a printed board with an optical waveguide.

Since the transparent resin plug 13 is formed in the through hole 3 in the printed circuit board with the optical waveguide manufactured in this way, this through hole is formed when the electric wiring board 10 and the waveguide board 20 are bonded together. The adhesive does not enter into 3, and the rigidity is also improved.

Further, since the electric wiring substrate 10 and the waveguide substrate 20 are bonded together by the transparent resin layer 12 instead of the conventional adhesive, workability is improved.

Further, since the waveguide substrate 20 is bonded after the through hole 3 is formed in the electric wiring substrate 10, the optical path conversion portion is not damaged and the transmission loss is not increased. This allows
A highly reliable printed circuit board with an optical waveguide can be manufactured in a stable manner.

Next, another embodiment of the present invention will be described.

FIG. 2 shows a sectional view of a printed circuit board with an optical waveguide manufactured by another method.

In this printed circuit board with an optical waveguide, the 45 ° mirror 11 is formed on the optical waveguide 2, and then the waveguide substrate 20 is formed.
Since it is manufactured by adhering the electric wiring substrate 10 to, the cutting groove formed by the cutter blade is not formed in the transparent resin plug 13.

Even with this structure, since the through hole 3 is filled with the transparent resin as in the present embodiment, this through hole is formed when the electric wiring substrate 10 and the waveguide substrate 20 are bonded together. The adhesive does not get into 3 and the rigidity is further improved.

Further, as a modification of the printed circuit board with the optical waveguide shown in FIG. 1, as shown in FIG. 3, the portion (cutting groove) of the waveguide substrate 20 where the 45 ° mirror 11 is formed becomes a space. The portion may be further filled with the transparent resin 14.

At this time, if the slope of the mirror 11 is coated with Au or the like, the reflectance can be increased and the difference in refractive index can be prevented from decreasing.

With this structure, the rigidity can be further improved.

In the present embodiment, the electric wiring board 10 and the waveguide board 20 are attached to each other with the transparent resin layer 12 sandwiched therebetween. The transparent resin plug 13 formed in 3 makes it difficult to protrude.

It goes without saying that a transparent resin layer may be sandwiched between the waveguide substrate 20 and the other electric wiring substrate 9 and they may be bonded together.

[0042]

In summary, according to the present invention, no adverse effects such as the protrusion of the adhesive when the substrates are laminated are caused, so that the transmission loss does not increase in the optical path conversion section.

Further, since the waveguide and the 45 ° mirror are also joined to the substrate with high rigidity, a highly reliable printed circuit board with an optical waveguide can be stably provided.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a printed circuit board with an optical waveguide showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a printed circuit board with an optical waveguide showing another embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a printed circuit board with an optical waveguide showing a modification of FIG.

4 (a) to 4 (f) are views for explaining a method of manufacturing the printed circuit board with the optical waveguide shown in FIG.

FIG. 5 is a partial cross-sectional view of a conventional printed circuit board with an optical waveguide.

FIG. 6 is a cross-sectional view of a waveguide element using a conventional printed circuit board with an optical waveguide.

FIG. 7 is a diagram for explaining a method of forming a cutting groove that intersects an optical waveguide with a cutter blade.

[Explanation of symbols]

1 electrical wiring 2 Optical waveguide 3 through holes 10 Electric wiring board 11 45 ° mirror (optical path conversion unit) 12 Transparent resin layer 13 Transparent resin stopper 20 Waveguide substrate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kanji Tanaka             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. F term (reference) 2H047 KA03 KB08 LA09 MA07 PA02                       PA15 PA24 PA28 QA05 RA08                       TA05 TA11 TA41                 5E338 AA16 AA18 BB75 CC10 EE11

Claims (4)

[Claims] 1. A waveguide substrate having an optical waveguide having a reflection surface formed at an end thereof for changing an optical path, and a through hole formed at a position of the reflection surface for transmitting light propagating through the optical waveguide. In a printed circuit board with an optical waveguide in which an electric wiring board for mounting an optical element for transmitting and receiving light propagating through the optical waveguide through the through hole is attached with an adhesive, the through hole is filled with a transparent resin. A printed circuit board with an optical waveguide, wherein a transparent resin stopper is formed. 2. The printed circuit board with an optical waveguide according to claim 1, wherein the adhesive is made of the same transparent resin as the transparent resin stopper. 3. A waveguide substrate on which an optical waveguide is formed, and an optical element for transmitting and receiving an optical signal to and from the optical waveguide through a through hole formed in a direction intersecting with the optical waveguide. In the method of manufacturing a printed circuit board with an optical waveguide, in which an electric wiring board on which electric wiring is formed is bonded, a transparent resin is filled in the through hole, and the waveguide board and the electric wiring board are made of a transparent resin. After bonding, in order to optically couple the through hole and the optical waveguide, at the intersection of the through hole and the optical waveguide, cut obliquely with respect to the optical axis of the optical waveguide by a cutting means. A method for manufacturing a printed circuit board with an optical waveguide, comprising forming a reflection surface for changing an optical path. 4. A waveguide substrate on which an optical waveguide is formed, and an optical element which transmits and receives an optical signal to and from the optical waveguide through a through hole formed in a direction intersecting with the optical waveguide. In the method of manufacturing a printed wiring board with an optical waveguide, in which an electrical wiring board having electrical wiring formed thereon is bonded, an intersection of the through hole and the optical waveguide is formed so as to optically couple the through hole and the optical waveguide. The portion is cut obliquely with respect to the optical axis of the optical waveguide by a cutting means to form a reflection surface for optical path conversion, and then the through hole is filled with a transparent resin, and the waveguide substrate and the A method of manufacturing a printed circuit board with an optical waveguide, which comprises laminating a transparent resin to an electric wiring board.