WO2007091733A2

WO2007091733A2 - Photoelectric converting device, manufacturing method of the same, and external waveguide

Info

Publication number: WO2007091733A2
Application number: PCT/JP2007/052797
Authority: WO
Inventors: Nobuyuki Asahi; Hiroyuki Yagyu; Yutaka Kinugasa; Takuya Matsumoto; Makoto Nishimura
Original assignee: Matsushita Electric Works, Ltd.
Priority date: 2006-02-09
Filing date: 2007-02-09
Publication date: 2007-08-16
Also published as: WO2007091733A3

Abstract

A photoelectric converting device IA includes: an optical element 4A that converts an electric signal to a light signal or a light signal to an electric signal; an IC circuit 5A that sends the electric signal to the optical element or receives the electric signal from the optical element; a mount substrate 3 having a waveguide 31 that optically couples to the optical element 4A; and an external waveguide 9 that can be optically coupled to the waveguide. An optical connector 8A is provided to the external waveguide at an end portion. The mount substrate 3 is provided with a fitting portion that aligns the waveguide 3A and the external waveguide 9 with respect to each other as the optical connector 8A fits therein.

Description

PHOTOELECTRIC CONVERTING DEVICE, MANUFACTURING METHOD OF THE

SAME, AND EXTERNAL WAVEGUIDE

Technical Field

The present invention relates to a photoelectric converting device, a manufacturing method of the same, and an external waveguide.

Background Art

Conventionally, a photoelectric converting device of a type described, for example, in Patent Document 1, has been known, in which a mount substrate on which is mounted a light emitting element that converts an electric signal to a light signal and a mount substrate on which is mounted a light receiving element that converts a light signal to an electric signal are mounted on a wiring board via circuit substrates. The circuit substrate is provided with an IC circuit to send an electric signal to the light emitting element or an IC circuit to receive an electric signal from the light receiving element .

In this photoelectric converting device, a waveguide that optically couples to the light emitting element or the light receiving element is provided to each mount substrate. and these waveguides overhang and extend from the mount substrates to be linked to each other at the tip ends by optical connectors provided at the tip ends.

When the waveguides overhang and extend from the mount substrates as described above, however, there is a need to run the waveguides when the mount substrates are mounted on the wiring board, which makes the mounting of the mount substrates tedious. In addition, there is a need to provide heat resistance to the waveguides and the optical connectors, so that the waveguides including the optical connectors can withstand a high mounting temperature during the mounting of the mount substrates. It is therefore necessary to form the waveguides and the optical connectors from expensive materials .

Patent Document 1: JP-A-2003-222746

Disclosure of the Invention

The invention was devised in view of the foregoing, and therefore has an object to provide a photoelectric converting device that facilitates the mounting of a mount substrate and makes it possible to form an optical connector or the like from inexpensive materials, a manufacturing method of the same, and an external waveguide used in the photoelectric converting device.

In order to solve the problems discussed above, a photoelectric converting device of the invention includes : an optical element that converts an electric signal to a light signal or a light signal to an electric signal; an IC circuit that sends the electric signal to the optical element or receives the electric signal from the optical element; a mount substrate having a waveguide that optically couples to the optical element; and an external waveguide that is an external waveguide configured so as to be optically coupled to the waveguide and provided with an optical connector at an end portion, wherein the mount substrate is provided with a fitting portion for aligning the waveguide and the external waveguide with respect to each other, as the optical connector fits with the fitting portion.

Also, an external waveguide of the invention is an external waveguide used for the photoelectric converting device described above and configured so as to be optically coupled to the waveguide in the mount substrate, wherein an optical connector allowed to fit with the fitting portion provided to the mount substrate is provided at an end portion.

Further, a manufacturing method of a photoelectric converting device of the invention is characterized by including: a step of forming a waveguide in a substrate having plural mount substrates at a position corresponding to each mount substrate; a step of forming a wiring pattern on each mount substrate on the substrate; a step of forming a fitting portion to fit with an optical connector of an external waveguide on the substrate at the position corresponding to each mount substrate; a step of mounting an optical element on the substrate at the position corresponding to each mount substrate; and a step of cutting the substrate into pieces of individual mount substrates.

According to the photoelectric converting device of the invention, because the external waveguide configured so as to be optically coupled to the waveguide in the mount substrate is included, it is possible to mount the mount substrate on a wiring board before the external waveguide is coupled to the waveguide . This eliminates the need to run the external waveguide during the mounting of the mount substrate, which facilitates the mounting of the mount substrate. In addition, because there is no need for the external waveguide and the optical connector to have heat resistance to withstand a high mounting temperature during the mounting of the mount substrate , it is possible to form the external waveguide and the optical connector from inexpensive materials. Moreover, because the mount substrate is provided with the fitting portion for aligning the waveguide and the external waveguide with respect to each other, as the optical connector fits with the fitting portion, it is possible to optically couple the waveguide and the external waveguide to each other at high efficiency.

Also, when the external waveguide of the invention is used, it is possible to optically couple the waveguide and the external waveguide to each other at high efficiency.

Further, according to the manufacturing method of the photoelectric converting device of the invention, it is possible to manufacture a photoelectric converting device that facilitates the mounting of the mount substrate on the wiring board and makes it possible to form the external waveguide and the optical connector from inexpensive materials .

Brief Description of the Drawings

FIG.1 is a view schematically showing the configuration of a photoelectric converting device according to a first embodiment of the invention.

FIG. 2A is a side view of a mount substrate on which an optical element is mounted, and FIG.2B is a cross section taken on line IIB-IIB of FIG. 2A.

FIG. 3 is a perspective view of the photoelectric converting device of the first embodiment.

FIG. 4 is a perspective view of a mount substrate when viewed from below.

FIG. 5 is a perspective view of an adapter.

FIG. 6 is a perspective view of an optical connector.

FIG. 7 is an exploded perspective view of the optical connector.

FIG. 8A is a perspective view of an external waveguide, and FIG. 8B is a cross section when the external waveguide is sandwiched between a first base portion and a second base portion.

FIG. 9A through FIG. 9C are explanatory views used to describe the fabrication sequence of the photoelectric converting device.

FIG. 1OA through FIG. 1OC are explanatory views used to describe the fabrication sequence of the photoelectric converting device.

FIG. HA through FIG. HC are explanatory views used to describe the fabrication sequence of the photoelectric converting device.

FIG. 12A is a plan view of a mount substrate after the waveguide is formed, FIG. 12B is a schematic cross section in part of this mount substrate, FIG. 12C is a plan view of a mount substrate after the waveguide is formed according to a modification of the manufacturing method, and FIG. 12D is a schematic cross section in part of this mount substrate.

FIG.13 is a view schematically showing the configuration of a photoelectric converting device according to a second embodiment .

FIG. 14A is a view schematically showing the configuration of a photoelectric converting device according to a third embodiment, and FIG. 14B and FIG. 14C are views schematically showing the configurations of modifications of the photoelectric converting device.

FIG. 15A is a view schematically showing the configuration of a photoelectric converting device according to a fourth embodiment, and FIG. 15B is a view schematically showing the configuration of a modification of the photoelectric converting device.

FIG.16 is a view schematically showing the configuration of a photoelectric converting device according to a fifth embodiment .

FIG.17 is a view schematically showing the configuration of a photoelectric converting device according to a sixth embodiment .

FIG. 18A is a view schematically showing the configuration of a photoelectric converting device according to a seventh embodiment, and FIG. 18B and FIG. 18C are views schematically showing the configurations of modifications of the photoelectric converting device.

FIG. 19A is a view schematically showing the configuration of a photoelectric converting device according to a ninth embodiment, and FIG. 19B is a view schematically showing the configuration of a modification of the photoelectric converting device.

FIG. 2OA is a perspective view of a photoelectric converting device according to a tenth embodiment when the mount substrate and the optical connector are viewed from below. FIG. 2OB is a perspective view of the optical connector, and FIG. 2OC is a cross section of the external waveguide.

FIG.21 is a view schematically showing the configuration of a photoelectric converting device according to an eleventh embodiment .

FIG. 22A is a perspective view of a modification of the mount substrate when viewed from below, and FIG. 22B is a perspective view of a modification of the adapter.

FIG. 23A is a perspective view of a modification of the adaptor, and FIG. 23B is a perspective view of a modification of the optical connector.

FIG.24A is a plan view when a modification of the optical connector is attached to a modification of the adapter, and FIG. 24B is a partially enlarged sectional front view when a pressing plane is provided to an engaging claw.

FIG. 25A is a perspective view of a modification of the mount substrate when viewed from below, FIG. 25B is a perspective view of a modification of the adapter, and FIG. 25C is a perspective view of a modification of the optical connector.

FIG. 26A is a perspective view of a modification of the adapter, and FIG. 26B is a schematic sectional side view when a modification of the adapter is attached to the optical connector. Best Mode for Carrying Out the Invention

Hereinafter, the best mode for carrying out the invention will be described in detail with reference to the drawings .

FIG. 1 shows a photoelectric converting device IA according to a first embodiment of the invention. The photoelectric converting device IA includes a photoelectric conversion portion IAl at the light emitting end, a photoelectric conversion portion 1A2 at the light receiving end, and an external waveguide 9 that optically couples these conversion portions IAl and 1A2 to each other. Referring to FIG.1, for ease of description, the vertical direction of FIG. 1 is defined as the top-bottom direction, and a direction perpendicular to the sheet surface is defined as the right-left direction; the right side and the left side of FIG.1 are defined, respectively, as the front and the rear of the photoelectric conversion portion IAl at the light emitting end; and the left side and the right side of FIG. 1 are defined, respectively, as the front and the rear of the photoelectric conversion portion 1A2 at the light receiving end.

The photoelectric conversion portion IAl at the light emitting end includes a wiring board 2 and a mount substrate 3 mounted on the top surface of the wiring board 2 while being spaced apart by a specific distance. Of the photoelectric conversion portion IAl at the light emitting end, a portion excluding the wiring board 2 and solder bumps 10 described below. that is, a portion mounted on the wiring board 2, is also referred to as an optical transmission module (the same can be said for the photoelectric conversion portion 1A2 at the light receiving end) . A first surface 3a, which is one of both surfaces of the mount substrate 3 in the plate thickness direction, serving as the bottom surface of the mount substrate 3 opposes the top surface of the wiring board 2. On this first surface 3a are mounted a light emitting element 4A that converts an electric signal to a light signal and an IC substrate 5A provided with an IC circuit 5OA to send an electric signal to the light emitting element 4A. The mount substrate 3 is provided with a waveguide 31 that optically couples to the light emitting element 4A.

A VCSEL (Vertical Cavity Surface Emitting Laser) that emits light upward from the top surface and has a size of 300 μm square when viewed in a plane is adopted as the light emitting element 4A. The IC substrate 5A is a driver IC that drives the VCSEL, and it is disposed in close proximity to the light emitting element 4A. The light emitting element 4A and the IC substrate 5A are connected to a wiring pattern 36 (see FIG. 9C) formed on the first surface 3a of the mount substrate 3, which will be described below, with gold bumps 11 (see FIG. 2A and FIG. 2B) . An LED or the like may be adopted as the light emitting element 4A. Because the LED or the like does not have directivity and a ratio to optically couple to the waveguide 31 is small, it can be adopted on the condition that there is a margin of optical transmission efficiency from the light emitting element to the light receiving element, that is, a light loss from the light emitting element to the light receiving element is small. When this condition is satisfied, the LED or the like is advantages owing to its low cost.

The mount substrate 3 is of a rectangular shape that extends in the front-back direction when viewed in a plane (see FIG. 3), and connected to an unillustrated wiring pattern formed on the top surface of the wiring board 2 with the solder bumps 10. A space between the mount substrate 3 and the wiring board 2 is of the order of 300 to 1000 μm. The mount substrate 3 requires rigidity to avoid influences of heat during the mounting and influences of a stress under the use environment. In the case of optical transmissions, because the optical transmission efficiency from the light emitting element to the light receiving element needs to be equal to or higher than a specific value, it is necessary to mount the optical element at a higher degree of accuracy and to suppress position displacement during use to the least possible extent. For these reasons, a silicon substrate is adopted as the mount substrate 3. Also, it is preferable that the mount substrate 3 is made of a material having a linear expansion coefficient close to that of the light emitting element 4A. Besides silicon, the mount substrate 3 may be made of a compound semiconductor, such as GaAs, based on the same materials of the VCSEL.

The mount substrate 3 is provided with a mirror portion 33 that bends an optical path by 90° at the position directly above the light emitting element 4A. The mirror portion 33 can be formed by vapor depositing gold or aluminum on a 45°-inclined plane formed by etching out the mount substrate 3. It should be noted that the 45°-inclined plane can be formed, for example, by means of anisotropic etching using a solution of potassium hydroxide.

The waveguide 31 extends forward from the mirror portion 33, and has an end face that is almost flush with the front end face of the mount substrate 3. As are shown in FIG. 2A and FIG. 2B, the waveguide 31 is formed of a core 31a having an almost square cross section and a clad 31b that covers the core 31a from the surrounding, and is disposed inside a waveguide forming groove 32 made in the mount substrate 3.

The sizes of the core 31a and the clad 31b are determined on the basis of a distance from the light emitting element 4A to the waveguide 31, the scattering angle of the light emitting element 4A, and the size of the light receiving element 4B described below by placing priority on the optical transmission efficiency.

For example, with a typical VCSEL and a PD (photo diode) serving as the light receiving element 4B used for high-speed transmissions at 5 to 10 Gbps or higher, the light emitting aperture and the scattering angle of the VCSEL are 5 to 10 μm and about 20° , respectively, and the light receiving aperture of the PD is about 60 μm. Hence, the size of the core 31a is determined to be 40 μm square and the thickness of the clad 31b is determined to be 2 to 10 μm.

In the case of short-distance in-device data transmissions, influences of scattering are so small that the optical transmission does not have to be a single mode transmission. It is therefore advantageous to use a multi-mode waveguide of a large size that facilitates the alignment . When a further higher speed is required, the single mode is used, and for a VCSEL serving as the light source and a PD, those having a fast response capability are selected.

The light emitting element 4A is mounted on the mount substrate 3 by means of flip chip bonding. The flip chip bonding can achieve a higher degree of mounting accuracy than die bonding or wire bonding, and by recognizing an alignment mark formed on the chip, mounting accuracy as good as 1 μm or smaller can be achieved. The IC substrate 5A is mounted on the mount substrate 3 simultaneously with the light emitting element 4A.

Although it is not shown in the drawing, a space between the light emitting element 4A and the mount substrate 3 and a space between the IC substrate 5A and the mount substrate 3 are filled with an underfill material. As the underfill material filled in the space between the light emitting element 4A and the mount substrate 3, for example, silicone resin or epoxy resin is suitable because not only transparency with respect to the light emitting wavelength of the light emitting element 4A is required, but also some degree of elasticity is required due to the characteristic of the VCSEL that varies with a stress. As the underfill material filled in the space between the IC substrate 5A and the mount substrate 3, for example, an epoxy material can be adopted in terms of mounting strength.

A crosswise pair of resin structure portions 6 spaced apart from each other with the waveguide 31 in between is provided on the first surface 3a of the mount substrate 3 at the front end portion (see FIG. 4), and an adapter 7A is also attached thereto . The external waveguide 9 is optically coupled to the waveguide 31 by attaching an optical connector 8A provided at the end portion of the external waveguide 9 to the adapter 7A.

Each resin structure portion 6 is made of, for example, heat curing materials, such as epoxy resin, acrylic resin, and silicone resin, or light curing materials, such as epoxy resin, acrylic resin, and silicone resin. As is shown in FIG. 4, it is of a plate-like trapezoidal shape when viewed in a plane. It should be noted that the wiring pattern 36 is omitted in FIG. 4. More specifically, opposing surfaces 61 of the resin structure portions 6 on the side they are opposed to each other are formed as inclined planes that widen outwards as they head toward the front. The opposing surfaces 61 and the first surface 3a of the mount substrate 3 define a fitting concave portion (fitting portion) 35 that opens along the waveguide 31 and widens toward the front while being closed at the top. A fitting hole 62 is made in the bottom surface of each resin structure portion 6.

As is shown in FIG. 5, the adapter 7A has a rectangular plate-like base portion 71 and a block portion 72 provided in a region that accounts for about 2/3 of the top surface of the base portion 71 on the front side. A crosswise pair of bosses 73 that can fit in the fitting holes 62 in the resin structure portions 6 is provided to protrude from the top surface of the base portion 71 on the rear side. As the bosses 73 fit into the fitting holes 62, the adapter 7A is attached to the mount substrate 3 in a state where the rear end face of the block portion 72 abuts on or comes in close proximity to the front end face of the mount substrate 3. The block portion 72 is also provided with an insertion hole 74 that penetrates through the block portion 72 in the front-back direction along the top surface of the base 71 at the position corresponding to the waveguide 31; moreover it is provided with concave engagement portions 75 formed in the both side surfaces on the right and the left. The optical connector 8A is configured to be attached to the front portion of the block portion 72 of the adapter 7A in a re-attachable manner. To be more concrete, as is shown in FIG. 6, the optical connector 8A includes a main portion 81 that extends in the right-left direction, hook portions 84 that extend backward from the both end portions of the main portion 81 and have engaging claws 84a that can engage with the engagement portions 75 of the adapter 7A at the tip ends, and an insertion portion 82 that extends backward from almost the center of the main body 81 in the right-left direction and is inserted into the insertion hole 74 of the adapter 7A.

By pushing in the optical connector 8A while inserting the insertion portion 82 into the insertion hole 74, the engaging claws 84a of the hook portions 84 engage with the engagement portions 75. The optical connector 8A is thus attached to the adapter 7A. In this instance, the rare end face of the insertion portion 82 abuts on the front end face of the mount substrate 3 via the insertion hole 74. The optical connector 8A can be removed from the adapter 7A by pulling out the optical connector 8A while the hook portions 84 are elastically deformed outwards.

To be more specific, as is shown in FIG. 7, the optical connector 8A is formed of a first base portion 8OA ad a second base portion 8OB that hold the external waveguide 9 by sandwiching it in a vertical direction, and each of the portions 81, 82, and 84 is divided into a top half and a bottom half (81A and 81B, 82A and 82B, and 84A and 84B). The external waveguide 9 is held by the first base portion 8OA and the second base portion 8OB while the end face is flush with the rear end face of the insertion portion 82. Hence, when the optical connector 8A is attached to the adapter 7A, the end face of the external waveguide 9 abuts on the end face of the waveguide 31. In addition, a plate-like fitting convex portion (second fitting portion) 83 that protrudes backward from the rear end face of the insertion portion 82 is provided continuously to the tip end of a lower insertion portion 82B of the second base portion 8OB.

As materials making of the adapter 7A and the optical connector 8A, for example, thermoplastic resin, heat curing resin, and ceramics materials, such as aluminum oxide and zirconia, are applicable. Examples of the thermoplastic resin include polyamide (PA), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyacetale (POM), poylbutylene terephthalate (PBT) , polycarbonate (PC) , polyether ketone (PEEK), and ABS resin. Examples of the heat curing resin include epoxy resin, silicone resin, unsaturated polyester resin, phenole resin, polyimide resin, diarylphthalate resin, polyurethane resin, melanin resin, and fluorocarbon resin.

As is shown in FIG. 8A, the external waveguide 9 is a flexible film having a specific width, and it is configured in such a manner that a core 92 is mounted on a bottom clad 91 and the core 92 is covered with a top clad 93.

At the end portions of the external waveguide 9 , the top clad 93 is not provided and the core 92 is bare. Positioning protruding strip portions 94, which are positioning convex portions, are provided to extend in parallel with the core 92 on the both sides. Meanwhile, a core groove 82a is provided at the center in the top surface of the bottom insertion portion 82B of the second base portion 8OB of the optical connector 8A, and positioning grooves 82b, which are positioning concave portions, are provided on the both sides thereof (see FIG. 7) . As is shown in FIG. 8B, the core 92 fits in the core groove 82a in a loose-fit state whereas the positioning strip portions 94 abut on the side surfaces of the positioning grooves 82b on the core groove 82a side. This configuration enables the external waveguide 9 to be aligned with respect to the second base portion 8OB at a higher degree of accuracy. By pressing the external waveguide 9 having the bottom clad 91 at the top while an optical adhesive 12 is applied to the top surface of the bottom insertion portion 82B, the external waveguide 9 and the second base portion 8OB are adhered to each other in a state where the core 92 and the positioning protruding strip portions 94 are meshed with the core groove 82a and the positioning grooves 82b, respectively, and spaces therebetween are filled with the optical adhesive 12. The external waveguide 9 may be a material other than a flexible film, and it may be a silica fiber or a plastic fiber. In addition, it is sufficient to provide the external waveguide 9 and the second base portion 8OB with a structure for their positioning. For example, a convex portion in the shape of a cylindrical column may be provided to the external waveguide 9 as the positioning convex portion and a concave portion for the convex portion to fit therein may be provided to the second base portion 8OB as the positioning concave portion. Alternatively, it is possible to provide the positioning concave portion to the first base portion 8OA.

Regarding the fitting convex portion 83 of the second base portion 8OB, the both side surfaces 83a are tapered so that they are able to come into plane-contact with the opposing surfaces 61 of the resin structure portions 6. When the optical connector 8A is attached to the adapter 7A, the fitting convex portion 83 is inserted into the fitting concave portion 35 through the insertion hole 74. The both side surfaces 83a then come into plane-contact with the opposing surfaces 61 while the top surface 83b comes into plane-contact with the first surface 3a of the mount substrate 3, which allows the fitting convex portion 83 to fit in the fitting concave portion 35. The waveguide 31 and the external waveguide 9 are thus aligned with respect to each other in the top-bottom direction and in the right-left direction. The position of the core 31a of the waveguide 31 consequently coincides with the position of the core 92 of the external waveguide 9. In short, by fitting the fitting convex portion 83 in the concave portion 35, the external waveguide 9 is aligned with respect to the waveguide 31 at a higher degree of accuracy. Optical coupling the waveguide 31 and the external waveguide 9 is thus enabled while the waveguide 31 and the external waveguide 9 are aligned with respect to each other at a higher degree of accuracy.

The basic configuration of the photoelectric conversion portion 1A2 at the light receiving end is the same as that of the photoelectric conversion portion IAl at the light emitting end. More specifically, in the photoelectric conversion portion 1A2 at the light emitting end, too, the fitting convex portion 83 fits in the fitting concave portion 35 as the optical connector 8A is attached to the adapter 7A, which allows the waveguide 31 and the external waveguide 9 to be aligned with respect to each other.

The photoelectric conversion portion 1A2 at the light receiving end is different from the photoelectric conversion portion IAl at the light emitting end in that a light receiving element 4B that converts a light signal to an electric signal and an IC substrate 5B provided with an IC circuit 5OB to receive an electric signal from the light receiving element 4B are mounted on the first surface 3a of the mount substrate 3. A PD is adopted as the light receiving element 4B and the IC substrate 5B is a TIA (Trans-impedance Amplifier) element that converts a current to a voltage. An amplifier element may occasionally be mounted on the mount substrate 3. Because the other configurations are the same as those of the photoelectric conversion portion IAl at the light emitting end, a detailed description thereof is omitted herein.

A manufacturing method of the photoelectric converting device IA will now be described with reference to FIG. 9A through FIG. HC. Regarding the photoelectric converting device IA, the photoelectric conversion portion IAl at the light emitting end and the photoelectric conversion portion 1A2 at the light receiving end can be manufactured separately, and the manufacturing method is the same. Hence, a manufacturing method of the photoelectric conversion portion IAl at the light emitting end will be described herein as a representative .

1) In this manufacturing method, as is shown in FIG. 9A, plural mount substrates 3 are formed simultaneously using a silicon wafer (silicon substrate) 20 having plural mount substrates 3 arrayed in a matrix fashion, and the silicon wafer 20 is cut into pieces of individual mount substrates 3 at the final stage. Referring to FIG. 9A through FIG. HA, the upper portion of the drawing shows the entire silicon wafer 20 and the lower portion of the drawing shows a portion corresponding to a single mount substrate 3 in an enlarged form. As the silicon wafer 20, a silicon wafer whose crystal orientation has been selected is prepared to perform etching in the following step.

2) As is shown in FIG. 9B, the waveguide forming groove

32 and the 45°-inσlined plane for forming the mirror portion

33 are formed in the silicon wafer 20 at a position corresponding to each mount substrate 3. These are formed by means of anisotropic etching that utilizes a difference in etching rate of the silicon crystal. In order to form the 45°-inclined plane, etching formation, etchant concentration, and composition are controlled. Besides the anisotropic etching, dry etching, such as reactive ion etching, is applicable to form the waveguide forming groove 32.

Etching conditions are different when the waveguide forming groove 32 having an almost rectangular cross section and the 45°-inclined plane are formed as are shown in FIG. 12A and FIG. 12B by means of anisotropic etching. In short, the compositions of an etching solution are different . Etching therefore has to be performed in two times . It should be noted, however, that it does not matter which etching is performed first.

Alternatively, when the waveguide forming groove 32 and the 45°-inclined plane are formed simultaneously, as are shown in FIG. 12C and FIG. 12D, the cross section of the waveguide forming groove 32 is formed in almost a trapezoidal shape, and the groove width of the waveguide forming groove 32 becomes larger. Because there will be no problem as long as the waveguide forming groove 32 does not reach a bonding pad for the light emitting element 4A formed in the following step, the waveguide forming section 32 can be formed also in the manner as described above .

3) As is shown in PIG. 9C, the wiring pattern 36 used to mount the light emitting element 4A is formed on each mount substrate 3 in the silicon wafer 20. In this step, the patterning is performed by vapor depositing gold onto the silicon wafer 20. In this instance, gold is vapor deposited on the 45°-inσlined planes at the same time so as to form the mirror portions 33. Although it depends on the wavelength used, it is possible to use the 45°-inclined planes directly as the mirror portions 33 without vapor deposing gold onto the 45°-inclined planes. However, for example, in a case where a near-infrared light source is used, reflectance can be increased by vapor depositing gold onto the 45°-inclined planes , which in turn increases the optical coupling efficiency between the light emitting element 4A and the waveguide 31.

4) As is shown in FIG. 1OA, the waveguide 31 is formed inside the waveguide forming groove 32. Initially, the waveguide forming groove 32 is filled with a clad material. A core groove (not shown) is then formed by pushing the clad material with a force using a mold (not shown) . Subsequently, the core 31a is formed by filling the core groove with a core material. Finally, the clad 31b is formed by applying the clad material onto the core 31a.

It should be noted that the waveguide 31 can be formed without using a mold. Initially, the entire silicon wafer 20 is allowed to undergo oxidation in a pyro-oxidation furnace at HOO⁰C for 250 min, so that an oxide silicon layer having a thickness of 1 to 2 μm is formed on the inner surface of the waveguide forming groove 32. The core 31a is then formed by filling the waveguide forming groove 32 with the core material, and the clad material having a refractive index close to that of oxide silicon is applied onto the core 31a. The clad 31b is thus formed from the oxide silicon layer and the clad material.

5) As is shown in FIG. 1OB, the fitting concave portion 35 is defined by forming the resin structure portions 6 on the silicon wafer 20 at a position corresponding to each mount substrate 3. As a method of forming the resin structure portions 6 , there are a forming method using a mold and a forming method using a mask pattern. To be more concrete, the entire silicon wafer 20 is heated while the mold is pressed against the silicon wafer 20 with the waveguides 31 having been formed therein after epoxy-based heat curing resin is applied to the silicon wafer 20. The heat curing resin is formed into a shape that conforms to the shape of the mold as its viscosity drops with a rise in temperature. Subsequently, the resin structure portions 6 are formed as the resin cures when it reaches the curing temperature. Regarding the formation by means of photo-curing, after photo-curing resin of a specific thickness is applied on the silicon wafer 20 by means of spin coating or the like, patterning is performed by means of exposure using a mask. The resin structure portions 6 are then formed by developing the pattern.

6) As is shown in FIG. 1OC, the light emitting element 4A and the IC substrate 5A are mounted on the silicon wafer 20 at a position corresponding to each mount substrate 3. The gold bumps 11 are provided to the light emitting element 4A and the IC substrate 5A by means of stud bump bonding. Ultrasonic bonding is then performed by heating the silicon wafer 20, the light emitting elements 4A, and the IC substrates 5A at 200⁰C.

After the light emitting element 4A and the IC substrate 5A are mounted, a space between the light emitting element 4A and the mount substrate 3 and a space between the IC substrate 5A and the mount substrate 3 are filled with an underfill material to enhance the bonding strength of the light emitting element 4A and the IC substrate 5A to the mount substrate 3. All of the emitting element 4A and the IC substrate 5A may be encapsulated with an elastic encapsulating material in order to enhance the environment resistance. 7) As is shown in FIG. HA, solder balls 10' having a diameter of 500 μm are mounted on an electrode portion formed from part of the wiring pattern 36. The solder balls 10' are disposed thereon after flux is applied. Thereafter, the silicon wafer 20 is cut into pieces of individual mount substrates 3.

8) As is shown in FIG. HB, the adapter 7A is attached to the mount substrate 3 by bonding the adapter 7A to the resin structure portions 6.

9) As is shown in FIG. HC, the photoelectric conversion portion IAl at the light emitting end can be manufactured by mounting the mount substrate 3 on the wiring board 2 at the specific position with the use of the solder balls 10 ' . The solder balls 10' are made of lead-free solder in view of environmental issues. The mounting temperature (reflow temperature) during the mounting of the mount substrate 3 is therefore set as high as 260°C.

When the optical connector 8A is attached to the adapter 7A, the fitting convex portion 83 fits in the fitting concave portion 35 and the end face of the waveguide 31 abuts on the end face of the external waveguide 9 , which allows the waveguide 31 and the external waveguide 9 to be optically coupled to each other. The end face of the waveguide 31 and the end face of the external waveguide 9 are kept abutted on each other by the engagement between the optical connector 8A and the adapter 7A. However, in order to minimize a light loss should a clearance develop therebetween, it is preferable to apply a refractive index matching material (in the form of gel) previously on the end face of the external waveguide 9.

The photoelectric converting device IA of the first embodiment includes the external waveguide 9 that can be optically coupled to the waveguide 31 in the mount substrate 3. It is thus possible to mount the mount substrate 3 on the wiring board 2 before the external waveguide 9 is coupled to the waveguide 31. This eliminates the need to run the external waveguide 9 during the mounting of the mount substrate 3 , which facilitates the mounting of the mount substrate 3. In addition , because there is no need for the external waveguide 9 and the optical connector 8A to have heat resistance to withstand a high mounting temperature during the mounting of the mount substrate 3, it is possible to form the external waveguide 9 and the optical connector 8A from inexpensive materials . Moreover, because the mount substrate 3 is provided with the fitting concave portion 35 that positions the waveguide 31 and the external waveguide 9 with respect to each other as the fitting convex portion 83 of the optical connector 8A fits therein, it is possible to optically couple the waveguide 31 and the external waveguide 9 to each other at high efficiency.

Also, because the resin structure portions 6 are provided on the mount substrate 3 and the fitting concave portion 35 is defined by the resin structure portions 6, it is possible to enhance the degree of freedom in design of the fitting concave portion 35.

In addition, because the adapter 7A, which holds the optical connector 8A when the optical connector 8A is attached thereto in a state where the fitting convex portion 83 fits in the concave portion 35, is attached to the mount substrate 3, the adapter 7A is able to maintain the waveguide 31 and the external waveguide 9 in an optically coupled state.

Further, because the light emitting element 4A or the light receiving element 4B and the IC substrate 5A or 5B are mounted on the mount substrate 3, a wiring distance between the IC substrate 5A or 5B and the light emitting element 4A or the light receiving element 4B can be shorter than in a case where the IC substrate 5A or 5B is mounted on the wiring board 2, which enables high-speed transmissions to be achieved. Further, by disposing the IC substrate 5A or 5B in close proximity to the light emitting element 4A or the light receiving element 4B, high-speed transmissions at 10 Gbps or higher can be readily achieved.

Because the external waveguide 9 is provided with positioning protruding strip portions 94 and the second base portion 8OB of the optical connector 8A is provided with the positioning grooves 82b for the positioning protruding strip portions 94 to fit therein, it is possible to position the external waveguide 9 with respect to the optical connector 8A at a higher degree of accuracy.

Further, because the external waveguide 9 is a flexible film, it is applicable, for example, to a bending portion of mobile devices, such as a mobile phone and a PDA (Personal Digital Assistance) . This enables high-speed signal transmissions of the order of several Gbps to be achieved as replacement for the conventional electric transmissions.

Furthermore, because the optical connector 8A is provided with the hook portions 84 that engage with the engagement portions 75 of the adapter 7A when attached to the adapter 7A, it is possible to prevent a fall-off of the optical connector 8A with the hook portions 84.

The first embodiment has described the photoelectric converting device IA of a one-way communication type for sending a light signal from the photoelectric conversion portion IAl at the light emitting end to the photoelectric conversion portion 1A2 at the light receiving end. However, the photoelectric converting device IA may be of a two-way communication type, in which the light receiving element 4B is provided to the photoelectric conversion portion IAl at the light emitting end and the light emitting element 4A is provided to the photoelectric conversion portion 1A2 at the light receiving end while the mount substrate 3 is provided with plural waveguides 31. It is then sufficient for the photoelectric converting device IA to include at least one of the photoelectric conversion portion IAl at the light emitting end and the photoelectric conversion portion 1A2 at the light receiving end, and the external waveguide 9. In addition, descriptions have been given for 1-channel communications regarding both the one-way communication type and the two-way communication type. However, multi-channel communications may be adopted by mounting an array of light receiving and emitting elements, and an external waveguide 9 provided with plural waveguides is used in this case.

A photoelectric converting device IB according to a second embodiment of the invention will now be described with reference to FIG.13. In the second and following embodiments , too, because the photoelectric conversion portion at the light receiving end is the same as the photoelectric conversion portion at the light emitting end, the photoelectric conversion portion at the light emitting end alone will be illustrated and described. Also, like components are labeled with like reference numerals with respect to the first embodiment and descriptions of such components are omitted.

As is shown in FIG. 13, in a photoelectric conversion portion IBl at the light emitting end in the photoelectric converting device IB of the second embodiment , the mount substrate 3 is mounted on the wiring board 2 in such a manner that, of both surfaces of the mount substrate 3 in the plate thickness direction, a first surface 3a to which is provided the waveguide 31 and on which is mounted the light emitting element 4A is the top surface and a second surface 3b is the bottom surface. The IC substrate 5A is mounted on the second surface 3b of the mount substrate 3 that opposes the wiring board 2. It should be noted that a space between the IC substrate 5A and the mount substrate 3 is filled with an underfill material as with the first embodiment .

The mount substrate 3 is provided with a penetrating electrode 37 that penetrates through the mount substrate 3 in the plate thickness direction, and the wiring pattern (not shown) formed on the first surface 3a and the wiring pattern (not shown) formed on the second surface 3b are electrically connected via the penetrating electrode 37. The penetrating electrode 37 can be formed by forming a through-hole in the mount substrate 3 by means of dry etching followed by plating or the like.

As the light emitting element 4A is mounted on the first surface 3a of the mount substrate 3 and the IC substrate 5A is mounted on the second surface 3b of the mount substrate 3 in this manner, the mounting areas can be secured on the both surfaces of the mount substrate 3, which makes it possible to reduce the mount substrate 3 in size.

Although it is not shown in the drawing, as with the first embodiment, the mount substrate 3 may be mounted on the wiring board 2 so that the first surface 3a of the mount substrate 3 is the bottom surface to oppose the wiring board 2.

A photoelectric converting device 1C according to a third embodiment of the invention is shown in Fig. 14A. As with the second embodiment, in a photoelectric conversion portion ICl at the light emitting end in the photoelectric converting device 1C of the third embodiment, the mount substrate 3 is mounted on the wiring board 2 in such a manner that the first surface 3a of the mount substrate 3 is the top surface.

The IC circuit 5OA to send an electric signal to the light emitting element 4A is directly formed on the second surface 3b of the mount substrate 3. In other words, the IC substrate 5A is furnished with the capability of the mount substrate 3. It should be noted that, as with the second embodiment, electrical conduction between the first surface 3a and the second surface 3b of the mount substrate 3 is provided by the penetrating electrode 37.

As the light emitting element 4A is mounted on the mount substrate 3 and the IC circuit 5OA is directly formed on the mount substrate 3 in this manner, not only is it possible to reduce the apparatus in size, but it is also possible to make the mounting sequence simpler by omitting the step of mounting the IC substrate 5A in comparison with a case where the IC circuit 5OA is formed on the IC substrate 5A.

It should be appreciated that the IC circuit 5OA is not necessarily formed on the second surface 3b, and as is shown in FIG. 14B, it may be formed on the first surface 3a. Alternatively, as is shown in FIG. 14C, the mount substrate 3 may be mounted on the wiring substrate 2 in the same manner as the first embodiment, so that the first surface 3a on which is mounted the light emitting element 4A and to which is provided the IC circuit 5OA is the bottom surface. When configured in this manner, the penetrating electrode 37 can be omitted.

A photoelectric converting device ID according to a fourth embodiment of the invention is shown in FIG. 15A. In a photoelectric conversion portion IDl at the light emitting end in the photoelectric converting device ID of the fourth embodiment , the light emitting element 4A is mounted on the IC substrate 5A and the IC substrate 5A is mounted on the first surface 3a of the mount substrate 3.

The light emitting element 4A is different from those shown in the first through third embodiments in that it is mounted using the surface opposite to the light emitting side. The light emitting element 4A is therefore mounted on the IC substrate 5A by means of die boding or wire bonding. Also, in order to secure a specific space between the IC substrate 5A and the mount substrate 3, the IC substrate 5A is connected to the wiring pattern (not shown) on the mount substrate 3 via solder bumps 110. When configured in this manner, it is necessary to position the IC substrate 5A and the mount substrate 3, that is, the light emitting element 4A and the mirror portion 33, at a higher degree of accuracy for reasons of the optical coupling efficiency between the light emitting element 4A and the waveguide 31. The light transmission efficiency from the light emitting element to the light receiving element is allocated to a loss through the components and a connection loss among the respective components , and the position accuracy is calculated from the connection loss. The overall optical transmission efficiency as defined above is determined from the intensity of the light emitting element 4A and the intensity of the light receiving element 4B. For example, because the light source output of the VCSEL is 3 dBm and the light receiving sensitivity of the PD is -18 dBm, the position accuracy between the light emitting element 4A and the mirror portion 33 is found to fall within ±5 μm.

It should be noted that a space between the IC substrate 5A and the mount substrate 3 is filled with light-transmitting resin as an underfill material (not shown) to suppress light scattering and to enhance the mounting strength.

As the light emitting element 4A is directly mounted on the IC substrate 5A provided with the IC circuit 5OA in this manner, the wiring distance between the IC circuit 5OA and the light emitting element 4A can be shorter, which enables high-speed transmissions to be achieved.

As is shown in FIG. 15B, it is possible to provide a concave portion 38 in the mount substrate 3 to prevent interference with the light emitting element 4A, so that the waveguide 31 is formed in and the resin structure portions 6 are provided to the bottom surface of the concave portion 38. When configured in this manner, it is possible to use the solder bumps 110 having a small diameter, which lessens an error in the position accuracy during the mounting of solder. It is thus possible to mount the IC substrate 5A at a further higher degree of accuracy.

A photoelectric converting device IE according to a fifth embodiment of the invention is shown in FIG. 16. In a photoelectric conversion portion IEl at the light emitting end in the photoelectric converting device IE of the fifth embodiment, the resin structure portions 6 are provided on the first surface 3a of the mount substrate 3 also at the rear end portion, and the IC substrate 5A on which is mounted the light emitting element 4A is mounted on the mount substrate 3 via the resin structure portions 6. The light emitting element 4A comes into a space between the resin structure portions 6 on the front side and the resin structure portions 6 on the rear side . In other words , the resin structure portions 6 serve as spacers that avoid interference between the mount substrate 3 and the light emitting element 4A. Also, a space between the IC substrate 5A and the mount substrate 3 is filled with an underfill material (not shown) as with the fourth embodiment .

As the IC substrate 5A is mounted on the mount substrate 3 via the resin structure portions 6 in this manner, it is possible to provide a positioning portion with respect to the IC substrate 5A to the resin structure portions 6 , which makes it possible to align the waveguide 31 and the light emitting element 4A with respect to each other at a higher degree of accuracy.

A photoelectric converting device IF according to a sixth embodiment of the invention is shown in FIG. 17. The photoelectric converting device IF of the sixth embodiment is of almost the same configuration as the photoelectric converting device IE of the fifth embodiment except that the mount substrate 3 is mounted on the wiring board 2 via the IC substrate 5A. When configured in this manner, it is possible to use the solder bumps 10 having a smaller diameter than in a case where the mount substrate 3 is directly mounted on the wiring board 2.

In addition, high-speed transmission elements are known to cause noises frequently. Hence, by disposing the mount substrate 3 to cover the light emitting element 4A as shown in FIG. 17, the mount substrate 3 serves as the ground, which makes it possible to achieve the noise suppression effect. It should be noted that this effect is achieved not only by the configuration shown in FIG. 17, but also by those shown in FIG. 1, FIG. 14C, FIG. 15A, FIG. 15B, and FIG. 16 as well as FIG. 21 described below.

A photoelectric converting device IG according to a seventh embodiment of the invention is shown in FIG. 18A. In a photoelectric conversion portion IGl at the light emitting end in the photoelectric converting device IG of the seventh embodiment, the light emitting element 4A and the IC substrate 5A are mounted on the first surface 3a of the mount substrate 3 opposing the wiring board 2, and the light emitting element 4A and the IC substrate 5A are disposed in a space between the mount substrate 3 and the wiring board 2 while a conductor layer 16 is provided on the second surface 3b of the mount substrate 3 on the opposite side of the first surface 3a. The conductor layer 16 is electrically connected to a ground wiring portion 21 of the wiring board 2 via an electric connection portion 17.

The conductor layer 16 is a metallic coating film formed across the entire second surface 3b of the mount substrate 3. The conductor layer 16 can be formed, for example, by means of plating, sputtering, vapor deposition, or the like.

The ground wiring portion 21 is made of a grounded pattern in the wiring pattern formed on the top surface of the wiring board 2. The other patterns are omitted in the drawing. The electric connection portion 17 is made of a metal material and. formed in a specific shape, and it is connected to the conductor layer 16 and the ground wiring portion 21 by solder or the like. Besides the metal materials, for example, a shielded wire or the like can be adopted as the electric connection portion 17.

As the light emitting element 4A and the IC substrate 5A are disposed in a space between the mount substrate 3 and the wiring board 2 and the conductor layer 16 , which is electrically connected to the ground wiring portion 21, is provided on the second surface 3b of the mount substrate 3 on the opposite side of the first surface 3a opposing the wiring board 2 in this manner, because the conductor layer 16 is allowed to function as an electric shield, it is possible to prevent an event that noises (EMI: Electro-Magnetic Interference) from the outside give influences to the IC element or the wiring pattern without having to provide a shielding member on the outside. Hence, when the high-frequency transmission signal characteristic is evaluated, jittering can be smaller and the rising time and the falling time of the waveform can be shorter, which enables signal transmissions to be achieved at a higher speed.

It is sufficient to provide the conductor layer 16 to the second surface 3b of the mount substrate 3 in a region that covers at least the light emitting element 4A, and the conductor layer 16 is not necessarily provided across the entire second surface 3b .

The electric connection portion 17 can be made of solder by providing the conductor layer 16 also to the rear end face of the mount substrate 3 as is shown in FIG. 18B, and by connecting the conductor layer 16 on this portion to the ground wiring portion 21 by solder.

Alternatively, as is shown in FIG. 18C, by providing the penetrating electrode 37 to the mount substrate 3 and connecting the penetrating electrode 37 to the ground wiring portion 21 via the bumps 10 made of solder or gold, it is possible to form the electric connection portion 17 from the penetrating electrode 37 and the bump 10. When configured in this manner, it is possible to provide the electric connection portion 17 within a region where the mount substrate 3 is present when viewed in a plane. It is thus possible to reduce the apparatus in size.

The penetrating electrode 37 can be formed in the same step of forming the conductor layer 16 by forming a through-hole in the mount substrate 3 by means of machining, etching, or the like and by subjecting the mount substrate 3 to plating or the like .

The configuration of the seventh embodiment is extensively applicable to a photoelectric converting device in which the light emitting element 4A and the IC circuit 5OA are disposed between the mount substrate 3 and the wiring board 2, and it is applicable to those shown in FIG. 14C and FIG. 15A through FIG. 17.

Although it is not shown in the drawing, a photoelectric converting device according to an eighth embodiment of the invention will now be described with reference to FIG. 18A. The photoelectric converting device of the eighth embodiment is of almost the same configuration as the photoelectric converting device IG of the seventh embodiment except for the configuration of the conductor layer 16.

More specifically, the mount substrate 3 in the eighth embodiment is a silicon substrate and the conductor layer 16 is a doped layer formed by doping an impurity at high concentration, such as boron and phosphorus, in the second surface 3b of the mount substrate 3.

By forming the conductor layer 16 by doping an impurity at high concentration in the second surface 3b of the mount substrate 3 that is a silicon substrate in this manner, the mount substrate 3 per se is allowed to function as a shield.

The penetrating electrode 37 may be provided by providing a through-hole in the mount substrate 3 and subjecting the inner peripheral surface of the through-hole to plating or the like in the same manner as in FIG. 18C after the doping step, so that the electric connection portion 17 is formed from the penetrating electrode 37 and the bumps 10. A photoelectric converting device IJ according to a ninth embodiment of the invention is shown in FIG. 19A. In a photoelectric conversion portion IJl at the light emitting end in the photoelectric converting device IJ of the ninth embodiment, plural concavities and convexities are provided alternately in the front-back direction on the surface of the conductor layer 16, which is a metallic coating film provided on the second surface 3b of the mount substrate 3 on the opposite side of the first surface 3a opposing the wiring board 2. The concavities and convexities on the conductor layer 16 can be formed by means of machining or etching.

As the concavities and convexities are provided on the surface of the conductor layer 16 in this manner, it is possible to secure a large surface area of the conductor layer 16. Heat generated in the light emitting element 4A is transmitted to the conductor layer 16 via the mount substrate 3 and is thus released in a satisfactory manner. The heat releasing performance for the heat generated in the light emitting element 4A can be therefore enhanced.

In a case where the conductor layer 16 is a doped layer, it is possible to form the conductor layer 16 having the concavities and convexities on the surface thereof by forming a concavo-convex shape on the second surface 3b of the mount substrate 3 as is shown in FIG. 19B by means of machining and etching, and then by doping an impurity at high concentration in the second surface 3b.

A photoelectric converting device IK according to a tenth embodiment of the invention is shown in FIG. 2OA. The wiring board 2 and the adapter 7A are omitted in FIG. 2OA. As is shown in FIG. 2OC, in the photoelectric converting device IK of the tenth embodiment, a crosswise pair of conductive wires 13 is provided on the bottom surface of the external waveguide 9. As is shown in FIG. 2OB, the conductive wires 13 extend to the fitting convex portion 83 by passing through the interior of the optical connector 8A and are also exposed on the top surface 83b of the fitting convex portion 83, thereby forming contact point portions 13a.

Meanwhile, the wiring pattern 36 extends to positions corresponding to the contact point portions 13a of the optical connector 8A on the first surface 3a of the mount substrate 3, thereby forming contact point portions 39. Hence, when the external waveguide 9 and the waveguide 31 are optically coupled to each other by attaching the optical connector 8A to the adapter 7A, the contact point portions 13a and the contact point portions 39 are electrically connected to each other.

As the conductive wires 13 are provided to the external waveguide 9 and the contact point portions 39 that can be electrically connected to the conductive wires 13 are provided to the mount substrate 3 in this manner, it is possible to achieve the optical coupling and the electrical connection at the same time.

It should be noted that the conductive wires 13 are not necessarily formed directly on the bottom surface of the external waveguide 9. The conductive wires 13 may be provided to the external waveguide 9 by forming the conductive wires 13 on a flexible circuit substrate made of polyimide or the like in the form of a wring pattern and by attaching this circuit substrate to the bottom surface of the external waveguide 9. In addition, the configuration of the tenth embodiment is applicable to any of the first through ninth embodiments described above.

A photoelectric converting device IL according to an eleventh embodiment of the invention is shown in FIG. 21. In the photoelectric converting device IL of the eleventh embodiment, the conductive wires 13 are provided to the external waveguide 9; however, the conductive wires 13 do not pass through the interior of the optical connector 8A, and instead, they are separated from the external waveguide 9 at the end portion of the external waveguide 9. Electric connectors 14 are provided to the conductive wires 13 at the end portions. Meanwhile, the wiring board 2 is provided with electric connectors 15 that can be connected to the electric connectors 14.

When configured in this manner, electric wiring can be achieved by rationally utilizing the external waveguide 9. It should be noted that the configuration of the eleventh embodiment is applicable to any of the first through ninth embodiments described above.

Each of the first through eleventh embodiments above has described the configuration in which the fitting concave portion 35 is defined by the resin structure portions 6. However, as is shown in PIG. 22A, it is possible to directly provide the fitting concave portion 35 in the mount substrate 3 by removing part of the mount substrate 3. In this case, the fitting concave portion 35 can be formed simultaneously when the waveguide forming groove 32 is formed in the etching step of forming the waveguide forming groove 32.

Further, by forming adapter fitting grooves 34 in the first surface 3a of the mount substrate 3 and by providing protruding strip portions 76 that can fit in the adapter fitting grooves 34 in the adapter 7A as is shown in FIG. 22B, the resin structure portions 6 can be omitted. The adapter fitting groove portions 34 can be also formed simultaneously when the waveguide forming groove 32 is formed in the etching step of forming the waveguide forming groove 32.

In each of the first through eleventh embodiments, instead of the adapter 7A and the optical connector 8A, it is possible to adopt an adapter 7B shown in FIG. 23A as a modification and an optical connector 8B shown in FIG. 23B as a modification. The adapter 7A and the optical connector 8A described above are configured in such a manner that the optical connector 8A is externally fit in the adapter 7A. On the contrary, the adapter 7B and the optical connector 8B of the modifications are configured in such a manner that the optical connector 8B is internally fit in the adapter 7B.

To be more concrete, in the adapter 7B, as is shown in FIG.23A, the block portion 72 is provided along the full width of the base portion 71 and the width of the insertion hole 74 is set larger. In addition, the engagement portions 75 are provided to the both side surfaces of the block portion 72 to communicate with the insertion hole 74.

Meanwhile, in the optical connector 8B, as is shown in FIG. 23B, the hook portions 84 are provided to extend forward from the rear end portions of the both side surfaces of the insertion portion 82, and engaging claws 84a face outward. Hence, when the optical connector 8B is inserted into the adapter 7B, the engaging claws 84a engage with the engagement portions 75 as is shown in FIG. 24A.

By providing a pressing plane 84b to the engaging claw 84a by inclining the surface of the engaging claw 84a on the side engaging with the engagement portion 75 as is shown in FIG. 24B, even after the optical connector 8B is attached to the adapter 7B, a pressing force that presses the optical connector 8B against the mount substrate 3 as is indicated by an arrow a works constantly on the optical connector 8B owing to a restoring force of the hook portion 84. It is therefore possible to suppress position displacement of the optical connector 8B. By adopting the structure by which the optical connector 8B is pressed against the mount substrate 3, a structure such that brings the waveguide 31 formed in the mount substrate 3 and the external waveguide 9 into close adhesion is achieved. This makes a space between the waveguides so small that the structure capable of suppressing a light loss can be achieved.

Also, as is shown in FIG. 25C, it is possible to provide two fitting convex portions 83 at positions having the external waveguide 9 in between. In this case, as is shown in FIG. 25A, the fitting concave portion 35 is provided to each resin structure portion 6. When configured in this manner, because the fitting convex portion 83 is absent below the end face of the external waveguide 9 , polishing can be readily applied to the end face of the external waveguide 9 while the external waveguide 9 is held in the optical connector 8B, which can in turn enhance the handling performance during assembly. Also, by providing plural fitting convex portions 83 , the positioning accuracy can be enhanced in comparison with a case where a single fitting convex portion 83 is provided.

Further, the thickness of the resin structure portions 6 is not necessarily the same as that of the fitting convex portion 83, and as is shown in FIG. 25A, they can be set thin. In this case, as is shown in FIG. 25B, a step portion 78 in the shape of releasing the fitting convex portions 83 is provided on the top surface of the base portion 71 of the adapter 7B at the rear end portion, and bosses 73 are provided to protrude from the top surface of the step portion 78. It should be noted that the configuration shown in FIG. 25B and FIG.25C are also applicable to the adapter 7A and the optical connector 8A shown in FIG. 5 and FIG. 6, respectively.

In addition, as an adaptor 7C shown in FIG. 26A as a modification, a guide portion 77 that forms a rising gradient toward the rear may be provided on the top surface of the base portion 71 at the rear end position. As is shown in FIG. 26B, the guide portion 77 is to guide the fitting convex portion 83 so as to be pressed against the mount substrate 3 when the fitting convex portion 83 of the optical connector 8A fits in the fitting concave portion 35.

When configured in this manner, the mount substrate 3 and the optical connector 8A are fixed while they come into contact with each other in a state where the fitting convex portion 83 fits in the fitting concave portion 35. It is therefore possible to prevent the position displacement between the waveguide 31 and the external waveguide 9 caused by vibrations , by being repetitively inserted and pulled out , and so forth. It should be noted that the configuration shown in FIG. 26A is also applicable to the adapter 7B . The fitting portion of the invention is not necessarily the fitting concave portion 35 in the shape that becomes concave in a direction along the waveguide 31 as has been described above , and it may be of a shape that becomes convex in a direction along the waveguide 31. In this case, the fitting portion is formed with ease by removing portions of the mount substrate 3 on the both sides of the waveguide 31 by means of etching. Also, in this case, a protruding portion of a two-forked shape may be formed at the tip end of the insertion portion 82 of the optical connectors 8A or 8B, and this protruding portion is used as second fitting portion of the invention. Further, when the fitting portion is formed in a convex shape, the fitting portion may be provided to protrude outwards from a region where the mount substrate 3 is present when viewed in a plane .

As has been described, a photoelectric converting device of the invention includes: an optical element that converts an electric signal to a light signal or a light signal to an electric signal; an IC circuit that sends the electric signal to the optical element or receives the electric signal from the optical element; a mount substrate having a waveguide that optically couples to the optical element; and an external waveguide that is an external waveguide configured so as to be optically coupled to the waveguide and provided with an optical connector at an end portion, wherein the mount substrate is provided with a fitting portion for aligning the waveguide and the external waveguide with respect to each other, as the optical connector fits with the fitting portion.

According to this configuration, because the external waveguide configured so as to be optically coupled to the waveguide in the mount substrate is provided, it is possible to mount the mount substrate on a wiring board before the external waveguide is coupled to the waveguide. This eliminates the need to run the external waveguide during the mounting of the mount substrate, which facilitates the mounting of the mount substrate. In addition, because there is no need for the external waveguide and the optical connector to have heat resistance to withstand a high mounting temperature during the mounting of the mount substrate, it is possible to form the external waveguide and the optical connector from inexpensive materials . Moreover, because the mount substrate is provided with the fitting portion for aligning the waveguide and the external waveguide with respect to each other, as the optical connector fit with the fitting portion, it is possible to optically couple the waveguide to the external waveguide at high efficiency.

In order to maintain a state where the waveguide and the external waveguide are optically coupled to each other, it is preferable that an adapter, to and from which the optical connector is attachable and detachable and which holds the optical connecter when the optical connector is attached thereto in a state where the optical connector fits with the fitting portion, is attached to the mount substrate.

In order to enable high-speed transmissions to be achieved, it is preferable that an IC substrate provided with the IC circuit is further included, and that the IC substrate and the optical element are mounted on the mount substrate.

In order to reduce the mount substrate in size, it is preferable that, the optical element is mounted on one of both surfaces of the mount substrate in a plate thickness direction, and the IC substrate is mounted on the other one.

In order to reduce the apparatus in size, it is preferable that the optical element is mounted on the mount substrate and the IC circuit is directly formed on the mount substrate.

In order to enable high-speed transmissions to be achieved, it is preferable that an IC substrate provided with the IC circuit is further included, and that the optical element is mounted on the IC substrate and the IC substrate is mounted on the mount substrate.

In order to enhance the degree of freedom in design of the fitting portion and to allow the waveguide and the optical element to be aligned with respect to each other at a higher degree of accuracy, it is preferable that the fitting portion is defined by a resin structure portion provided on the mount substrate, and that the IC substrate is mounted on the mount substrate via the resin structure portion.

In order to allow a solder bump having a small diameter to be used, it is preferable that the mount substrate is mounted on a wiring board via the IC substrate.

In order to prevent deterioration of a high-frequency signal without having to provide a shielding member on the outside, it is preferable that: a wiring board having a ground wiring portion to be grounded is further included, on which the mount substrate is mounted while being spaced apart by a specific distance so as to be opposed to one of both surfaces of the mount substrate in a plate thickness direction or the other one; the optical element and the IC circuit are disposed between the mount substrate and the wiring board; a conductor layer is provided on the surface of the mount substrate on an opposite side of the surface opposing the wiring board in a region that covers at least the optical element; and the conductor layer and the ground wiring portion on the wiring board are electrically connected via an electric connection portion.

In order to achieve a reduction of the apparatus in size, it is preferable that the electric connection portion is formed of a penetrating electrode provided in the mount substrate and a bump that connects the penetrating electrode and the ground wiring portion.

In order to allow the mount substrate per se to function as a shield, it is preferable that the mount substrate is a silicon substrate, and that the conductor layer is formed by doping an impurity at high concentration in the surface of the mount substrate on the opposite side of the surface opposing the wiring board.

In order to enhance the heat releasing performance for heat generated in the light emitting element, it is preferable that concavities and convexities are provided on a surface of the conductive layer.

In order to achieve the optical coupling and the electrical connection at the same time, it is preferable that the external waveguide is provided with a conductive wire, and that the mount substrate is provided with a contact point portion that is electrically connected to the conductive wire when the external waveguide and the waveguide are optically coupled to each other as the optical connector fits with the fitting portion.

In order to achieve the electric wiring by rationally utilizing the external waveguide, it is preferable that the external waveguide is provided with a conductive wire having an electric connector at an end portion.

In the photoelectric converting device, it may be configured in such a manner that the fitting portion has a shape that becomes convex or concave in a direction along the waveguide, and that the optical connector has a second fitting portion allowed to fit with the fitting portion.

In order to position the external waveguide with respect to the optical connector at a higher degree of accuracy, it is preferable that: the optical connector has a first base portion and a second base portion that hold the external waveguide by sandwiching the external waveguide; the external waveguide is provided with a positioning convex portion; and the first base portion or the second base portion is provided with a positioning concave portion to fit with the convex portion.

In order to enable applications to a bending portion of equipment, it is preferable that the external waveguide is a flexible film.

In order to prevent a fall-off of the optical connector, it is preferable that the optical connector is provided with a hook portion that engages with the adapter when attached to the adapter.

In order to prevent position displacement between the waveguide and the external waveguide caused by vibrations, by being repetitively inserted and pulled out, and so forth, it is preferable for the photoelectric converting device in which the adapter is attached to the mount substrate as described above that: the fitting portion has a shape that becomes convex or concave in a direction along the waveguide; the optical connector has a second fitting portion allowed to fit with the fitting portion; and the adapter is provided with a guide portion that guides the second fitting portion to be pressed against the mount substrate when the second fitting portion fits with the fitting portion.

Claims

1. A photoelectric converting device, comprising: an optical element that converts an electric signal to a light signal or a light signal to an electric signal; an IC circuit that sends the electric signal to the optical element or receives the electric signal from the optical element; a mount substrate having a waveguide that optically couples to the optical element; and an external waveguide that is an external waveguide configured so as to be optically coupled to the waveguide and provided with an optical connector at an end portion, wherein the mount substrate is provided with a fitting portion for aligning the waveguide and the external waveguide with respect to each other, as the optical connector fits with the fitting portion.

2. The photoelectric converting device according to Claim 1 , wherein : an adapter, to and from which the optical connector is attachable and detachable and which holds the optical connector when the optical connector is attached thereto in a state where the optical connector fits with the fitting portion, is attached to the mount substrate.

3. The photoelectric converting device according to Claim 1 or 2, further comprising: an IC substrate provided with the IC circuit, wherein the IC substrate and the optical element are mounted on the mount substrate.

4. The photoelectric converting device according to Claim 3 , wherein : the optical element is mounted on one of both surfaces of the mount substrate in a plate thickness direction, and the IC substrate is mounted on the other one.

5. The photoelectric converting device according to Claim 1 or 2, wherein: the optical element is mounted on the mount substrate and the IC circuit is directly formed on the mount substrate.

6. The photoelectric converting device according to Claim 1 or 2, further comprising: an IC substrate provided with the IC circuit, wherein the optical element is mounted on the IC substrate and the IC substrate is mounted on the mount substrate.

7. The photoelectric converting device according to Claim 6, wherein: the fitting portion is defined by a resin structure portion provided on the mount substrate, and the IC substrate is mounted on the mount substrate via the resin structure portion.

8. The photoelectric converting device according to Claim 7, wherein: the mount substrate is mounted on a wiring board via the IC substrate.

9. The photoelectric converting device according to any of Claims 1 through 3 and Claims 5 through 8, further comprising: a wiring board having a ground wiring portion to be grounded, on which the mount substrate is mounted while being spaced apart by a specific distance so as to be opposed to one of both surfaces of the mount substrate in a plate thickness direction or the other one, wherein : the optical element and the IC circuit are disposed between the mount substrate and the wiring board; a conductor layer is provided on the surface of the mount substrate on an opposite side of the surface opposing the wiring board in a region that covers at least the optical element; and the conductor layer and the ground wiring portion on the wiring board are electrically connected via an electric connection portion.

10. The photoelectric converting device according to Claim 9, wherein: the electric connection portion is formed of a penetrating electrode provided in the mount substrate and a bump that connects the penetrating electrode and the ground wiring portion.

11. The photoelectric converting device according to Claim 9 or 10, wherein: the mount substrate is a silicon substrate; and the conductor layer is formed by doping an impurity at high concentration in the surface of the mount substrate on the opposite side of the surface opposing the wiring board.

12. The photoelectric converting device according to any of Claims 9 through 11, wherein: concavities and convexities are provided on a surface of the conductive layer.

13. The photoelectric converting device according to any of Claims 1 through 12, wherein: the external waveguide is provided with a conductive wire; and the mount substrate is provided with a contact point portion that is electrically connected to the conductive wire when the external waveguide and the waveguide are optically coupled to each other as the optical connector fits with the fitting portion.

14. The photoelectric converting device according to any of Claims 1 through 12, wherein: the external waveguide is provided with a conductive wire having an electric connector at an end portion.

15. The photoelectric converting device according to Claim 1 , wherein: the fitting portion has a shape that becomes convex or concave in a direction along the waveguide; and the optical connector has a second fitting portion allowed to fit with the fitting portion.

16. The photoelectric converting device according to Claim 1, wherein: the optical connector has a first base portion and a second base portion that hold the external waveguide by sandwiching the external waveguide; the external waveguide is provided with a positioning convex portion; and the first base portion or the second base portion is provided with a positioning concave portion to fit with the convex portion.

17. The photoelectric converting device according to Claim 1, wherein: the external waveguide is a flexible film.

18. The photoelectric converting device according to Claim 2 , wherein: the optical connector is provided with a hook portion that engages with the adapter when attached to the adapter .

19. The photoelectric converting device according to Claim 2, wherein: the fitting portion has a shape that becomes convex or concave in a direction along the waveguide,- the optical connector has a second fitting portion allowed to fit with the fitting portion; and the adapter is provided with a guide portion that guides the second fitting portion to be pressed against the mount substrate when the second fitting portion fits with the fitting portion.

20. An external waveguide used for the photoelectric converting device according to any of Claims 1 through 19 and configured so as to be optically coupled to the waveguide in the mount substrate, wherein an optical connector allowed to fit with the fitting portion provided to the mount substrate is provided at an end portion.

21. A manufacturing method of a photoelectric converting device, characterized by comprising: a step of forming a waveguide in a substrate having plural mount substrates at a position corresponding to each mount substrate; a step of forming a wiring pattern on each mount substrate on the substrate; a step of forming a fitting portion to fit with an optical connector of an external waveguide on the substrate at the position corresponding to each mount substrate; a step of mounting an optical element on the substrate at the position corresponding to each mount substrate; and a step of cutting the substrate into pieces of individual mount substrates.