Photoelectric composite structure and active optical cable

Abstract

To provide a photoelectric composite structure and an active optical cable that can suppress the decrease in optical transmission efficiency. [Solution] The photoelectric mixed-signal substrate 1 comprises a flexible circuit board 2, an optical waveguide film 3, and a photodetector 42. The flexible circuit board 2 is arranged on one side in the thickness direction of the optical waveguide film 3. The optical waveguide film 3 comprises a core layer 32 made of a core material extending along its longitudinal direction, a cladding layer 34 made of a cladding material arranged to surround the core layer in the width and thickness directions, and an intermediate layer 35 containing the core material and cladding material and arranged between the core layer 32 and the cladding layer 34. The core layer 32 includes a photodetector-side mirror 36B that converts the optical path of the optical signal toward the photodetector 42. The photodetector 42 includes a photodetector aperture 44. The photodetector aperture 44 and the photodetector-side mirror 36B overlap in the thickness direction of the photoelectric mixed-signal substrate 1. The widthwise length of the photodetector aperture 44 is greater than the widthwise length of the photodetector-side mirror 36B.

Description

Technical Field

[0001] The present invention relates to an optoelectronic composite structure and an active optical cable.

Background Art

[0002] An optoelectronic composite structure is a structure that transmits optical signals and electrical signals. Conventionally, an optoelectronic hybrid substrate is known as an optoelectronic composite structure. The optoelectronic hybrid substrate includes, for example, an optical waveguide and an electrical circuit board in order along the thickness direction, and an optical element is mounted on the electrical circuit board.

[0003] As an optoelectronic hybrid substrate, for example, the following optoelectronic hybrid substrate has been proposed. That is, the optoelectronic hybrid substrate includes an optical waveguide and an electrical circuit board. The optical waveguide includes a core layer and a mirror. And an optical element is mounted on the electrical circuit board. In such an optoelectronic hybrid substrate, an electrical signal output from an external substrate is input to the optical element and converted into an optical signal. Then, the optical signal is emitted toward the core layer, the optical path is converted by the mirror, and the core layer is transmitted. Further, the optical signal transmitted through the core layer is converted in the optical path by the mirror, is incident on the optical element, and is converted into an electrical signal. Then, the electrical signal is input to the external substrate (see, for example, Patent Document 1 below).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, optical signals have the property of diffusing and / or scattering in the atmosphere. Therefore, when an optical signal transmitted through the core layer is converted by a mirror and incident on an optical element, it may diffuse and / or scatter. As a result, in the above-mentioned photoelectric mixed-signal substrate, when the optical signal is incident on the optical element, loss of the optical signal may occur, and an increase in reflected light may also occur. Consequently, in the above-mentioned photoelectric mixed-signal substrate, a decrease in the efficiency of optical signal transmission (hereinafter referred to as optical transmission) may occur.

[0006] The present invention relates to a photoelectric composite structure and an active optical cable that can suppress a decrease in optical transmission efficiency. [Means for solving the problem]

[0007] The present invention [1] is a photoelectric composite structure having a long shape, the photoelectric composite structure comprising an electrical circuit board, an optical waveguide, and a light-receiving element, the electrical circuit board being arranged on one side in the thickness direction of the optical waveguide, the optical waveguide comprising a core layer made of a core material extending along the longitudinal direction, a cladding layer made of a cladding material being arranged to surround the core layer in the width direction and thickness direction perpendicular to the longitudinal direction, and containing the core material and the cladding material, the The photoelectric composite structure includes an intermediate layer disposed between a core layer and the cladding layer, the core layer includes a light-receiving mirror that converts the optical path of an optical signal toward the photoreceiving element, the photoreceiving element is mounted on the electrical circuit board and includes a light-receiving port that receives the optical signal whose optical path has been converted by the light-receiving mirror, the light-receiving port and the light-receiving mirror overlap in the thickness direction of the photoelectric composite structure, and the widthwise length of the light-receiving port is greater than the widthwise length of the light-receiving mirror.

[0008] The above-described photoelectric composite structure comprises an electrical circuit board, an optical waveguide, and a photodetector. The optical waveguide comprises a core layer made of a core material and equipped with a photodetector-side mirror, a cladding layer made of a cladding material, and an intermediate layer containing the core material and the cladding material.

[0009] Furthermore, in the above-described photoelectric composite structure, the widthwise length of the light-receiving aperture of the light-receiving element is greater than the widthwise length of the light-receiving mirror in the core layer.

[0010] Therefore, in the above-described photoelectric composite structure, even when the optical signal reflected at the light-receiving mirror of the core layer is diffused and / or scattered, the optical signal is efficiently received at the relatively large light-receiving aperture. As a result, the above-described photoelectric composite structure can suppress a decrease in optical transmission efficiency.

[0011] The present invention [2] includes the photoelectric composite structure described in [1] above, wherein the ratio of the widthwise length of the light-receiving aperture to the widthwise length of the light-receiving mirror exceeds 1.0.

[0012] In the above-described photoelectric composite structure, the size of the light-receiving mirror and the size of the light-receiving aperture are adjusted so that the ratio of the width direction length of the light-receiving aperture to the width direction length of the light-receiving mirror exceeds a predetermined value. Therefore, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0013] The present invention [3] includes a photoelectric composite structure according to [1] or [2] above, wherein the reflective surface of the light-receiving mirror has a light-receiving curved surface that bulges from the other longitudinal side of the core layer toward the one longitudinal side, and the curvature of the light-receiving curved surface is 100 or more.

[0014] In the above-described photoelectric composite structure, the curvature of the light-receiving surface of the light-receiving mirror is adjusted to a predetermined value or higher. Therefore, the above-described photoelectric composite structure can improve the optical transmission efficiency.

[0015] The present invention [4] further includes a photoelectric composite structure according to any one of the above [1] to [3], comprising a light-emitting element, wherein the core layer comprises a light-emitting side mirror for converting the optical path of an optical signal emitted from the light-emitting element, the light-emitting element comprises a light-emitting port for transmitting an optical signal toward the light-emitting side mirror, the light-emitting port and the light-emitting side mirror overlap in the thickness direction of the photoelectric composite structure, and the widthwise length of the light-emitting port is smaller than the widthwise length of the light-emitting side mirror.

[0016] The above-described photoelectric composite structure includes a light-emitting element, and the optical waveguide is made of a core material and includes a light-emitting side mirror. In the above-described photoelectric composite structure, the widthwise length of the light-emitting aperture of the light-emitting element is smaller than the widthwise length of the light-emitting side mirror of the core layer.

[0017] Therefore, in the above-described photoelectric composite structure, even when the optical signal emitted from the light-emitting element diffuses and / or scatters, it is efficiently reflected by the relatively large light-emitting mirror. As a result, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0018] The present invention [5] includes the photoelectric composite structure described in [4] above, wherein the ratio of the widthwise length of the light-emitting opening to the widthwise length of the light-emitting mirror is 0.9 or less.

[0019] In the above-described photoelectric composite structure, the size of the light-emitting mirror and the size of the light-emitting aperture are adjusted so that the ratio of the width direction length of the light-emitting aperture to the width direction length of the light-emitting mirror is less than or equal to a predetermined value. Therefore, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0020] The present invention [6] includes the photoelectric composite structure described in [5] above, wherein the ratio of the widthwise length of the light-emitting opening to the widthwise length of the light-emitting mirror is 0.1 or more and 0.5 or less.

[0021] In the above-described optoelectronic composite structure, the sizes of the light-emitting side mirror and the light-emitting aperture are adjusted such that the ratio of the width-direction length of the light-emitting aperture to the width-direction length of the light-emitting side mirror falls within a predetermined range. Therefore, according to the above-described optoelectronic composite structure, a decrease in light transmission efficiency can be further suppressed.

[0022] The present invention [7] includes the optoelectronic composite structure according to any one of [4] to [6] above, in which the reflecting surface of the light-emitting side mirror has a light-emitting side curved surface that is recessed from the other side in the longitudinal direction of the core layer toward the one side, and the curvature of the light-emitting side curved surface is 100 or more.

[0023] In the above-described optoelectronic composite structure, the curvature of the light-emitting side curved surface of the light-emitting side mirror is adjusted to be a predetermined value or more. Therefore, according to the above-described optoelectronic composite structure, an improvement in light transmission efficiency can be achieved.

[0024] The present invention [8] includes the optoelectronic composite structure according to any one of [4] to [7] above, in which the ratio of the width-direction length of the core layer to the sum of the width-direction lengths of the intermediate layer disposed on one side in the width direction of the core layer and the intermediate layer disposed on the other side in the width direction of the core layer is 0.6 or more.

[0025] In the above-described optoelectronic composite structure, the sizes of the core layer and the intermediate layer are adjusted such that the ratio of the width-direction length of the core layer to the sum of the width-direction length of the core layer, the width-direction length of the intermediate layer disposed on one side in the width direction of the core layer, and the width-direction length of the intermediate layer disposed on the other side in the width direction of the core layer becomes a predetermined value or more. Therefore, according to the above-described optoelectronic composite structure, a decrease in light transmission efficiency can be further suppressed.

[0026] The present invention [9] includes the optoelectronic composite structure according to any one of [4] to [8] above, in which the ratio of the width-direction length of the core layer to the sum of the width-direction lengths of the intermediate layer disposed on one side in the width direction of the core layer and the intermediate layer disposed on the other side in the width direction of the core layer in the light-receiving side mirror is 0.9 or more.

[0027] In the above-described optoelectronic composite structure, in the light-receiving side mirror, the ratio of the widthwise length of the core layer to the total of the widthwise length of the intermediate layer disposed on one side in the width direction of the core layer and the widthwise length of the intermediate layer disposed on the other side in the width direction of the core layer 32 is a predetermined value or more. Thus, the sizes of the core layer and the intermediate layer are adjusted. Therefore, according to the above-described optoelectronic composite structure, a decrease in the optical transmission efficiency can be further suppressed.

[0028] The present invention

[10] includes the optoelectronic composite structure according to any one of [4] to [9] above, in which the ratio of the widthwise length of the core layer to the total of the widthwise length of the intermediate layer disposed on one side in the width direction of the core layer, the widthwise length of the intermediate layer disposed on the other side in the width direction of the core layer, and the widthwise length of the core layer in the light-emitting side mirror is 0.6 or more.

[0029] In the above-described optoelectronic composite structure, in the light-emitting side mirror, the ratio of the widthwise length of the core layer to the total of the widthwise length of the intermediate layer disposed on one side in the width direction of the core layer, the widthwise length of the intermediate layer disposed on the other side in the width direction of the core layer 32 is a predetermined value or more. Thus, the sizes of the core layer and the intermediate layer are adjusted. Therefore, according to the above-described optoelectronic composite structure, a decrease in the optical transmission efficiency can be further suppressed.

[0030] The present invention

[11] includes the optoelectronic composite structure according to

[10] above, in which the difference between the ratio of the widthwise length of the core layer to the total of the widthwise length of the intermediate layer disposed on one side in the width direction of the core layer, the widthwise length of the intermediate layer disposed on the other side in the width direction of the core layer, and the widthwise length of the core layer in the light-receiving side mirror and the ratio of the widthwise length of the core layer to the total of the widthwise length of the intermediate layer disposed on one side in the width direction of the core layer, the widthwise length of the intermediate layer disposed on the other side in the width direction of the core layer, and the widthwise length of the core layer in the light-emitting side mirror is 0.2 or more.

[0031] In the above-described photoelectric composite structure, the size of the core layer and the size of the intermediate layer are adjusted so that the difference between the ratio of the width direction length of the light-receiving mirror and the ratio of the width direction length of the light-emitting mirror is greater than or equal to a predetermined value. Therefore, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0032] The present invention

[12] includes a photoelectric composite structure according to any one of the above [4] to

[11] , wherein a composite member containing the core material and the cladding material is arranged on the reflective surface of the light-emitting mirror, and the reflective surface of the light-emitting mirror is roughened by the composite member.

[0033] In the above-described photoelectric composite structure, the reflective surface of the light-emitting mirror is roughened. Therefore, the above-described photoelectric composite structure can suppress the return of the optical signal from the light-emitting mirror to the light-emitting element. As a result, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0034] The present invention

[13] includes a photoelectric composite structure according to any one of the above [4] to

[12] , wherein the ratio of the widthwise length of the core layer in the light-receiving mirror to the widthwise length of the core layer in the light-emitting mirror is 0.5 or more and less than 1.0.

[0035] In the above-described photoelectric composite structure, the size of the core layer is adjusted so that the ratio of the widthwise length of the core layer in the light-emitting mirror to the widthwise length of the core layer in the light-receiving mirror falls within a predetermined range. Therefore, the above-described photoelectric composite structure can suppress a decrease in optical transmission efficiency.

[0036] The present invention

[14] includes the photoelectric composite structure described in

[12] or

[13] above, wherein the widthwise length of the core layer decreases from the other longitudinal side toward the one longitudinal side.

[0037] In the above-described photoelectric composite structure, the widthwise length of the core layer decreases as it moves from the other side of the longitudinal direction towards the one side of the longitudinal direction. Therefore, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0038] The present invention

[15] includes an active optical cable comprising a photoelectric composite structure as described in any one of the above [1] to

[14] .

[0039] The above-mentioned active optical cable incorporates a photoelectric composite structure, which helps to suppress a decrease in optical transmission efficiency. [Effects of the Invention]

[0040] The photoelectric composite structure and active optical cable of the present invention can suppress a decrease in optical transmission efficiency. [Brief explanation of the drawing]

[0041] [Figure 1] Figure 1 is a schematic side view of a photoelectric composite substrate, which is one embodiment of the photoelectric composite structure of the present invention. [Figure 2] Figure 2 is a schematic plan view showing the light-emitting element of the photoelectric mixed-signal substrate shown in Figure 1, and its surroundings in an enlarged view. [Figure 3] Figure 3 is a schematic plan view showing the photodetector and its surroundings in the photoelectric mixed-signal substrate shown in Figure 1, with some magnification. [Figure 4] Figure 4 is a schematic plan view showing an enlarged view of the light-emitting element and its surroundings in a photoelectric composite substrate, which is another embodiment of the photoelectric composite structure of the present invention (specifically, a form in which the reflective surface of the light-emitting mirror is roughened). [Figure 5] Figure 5 is a schematic plan view of a photoelectric composite substrate representing another embodiment of the photoelectric composite structure of the present invention (specifically, a configuration in which the widthwise length of the core layer decreases as it moves from the other side of the longitudinal direction toward the one side of the longitudinal direction). [Modes for carrying out the invention]

[0042] (definition) In this specification, curvature refers to the value determined by a laser microscope. Furthermore, in this specification, the intermediate layer described later refers to a layer formed by mixing the core material described later and the cladding material described later. Specifically, when the Raman spectrum of the mirror described later is measured by Raman spectroscopy, and the maximum peak intensity of the region containing only the core material is set to 1.0, and the maximum peak intensity of the region containing only the cladding material is set to 2.5, the intermediate layer means a peak intensity greater than 1.0 and less than 2.5.

[0043] 1. Photoelectric mixed-signal substrate 1) Overall structure In the following description, a photoelectric composite substrate 1, as one embodiment of the photoelectric composite structure, will be explained with reference to Figure 1.

[0044] The photoelectric integrated substrate 1 has a long shape. More specifically, the photoelectric integrated substrate 1 has a flat strip shape extending along its longitudinal direction. The photoelectric integrated substrate 1 is used for the transmission of optical signals (hereinafter referred to as optical transmission). That is, when in use, the photoelectric integrated substrate 1 is electrically connected to two external substrates 100. More specifically, one end of the photoelectric integrated substrate 1 in the longitudinal direction is electrically connected to the transmitting external substrate 101 (see dashed line in Figure 1), which is an external substrate 100. Also, the other end of the photoelectric integrated substrate 1 in the longitudinal direction is electrically connected to the receiving external substrate 102 (see dashed line in Figure 1), which is an external substrate 100. The photoelectric integrated substrate 1 then transmits optical signals between the transmitting external substrate 101 and the receiving external substrate 102 (see dashed line in Figure 1).

[0045] More specifically, the photoelectric mixed-signal substrate 1 comprises a flexible circuit board 2 as an electrical circuit board, an optical waveguide film 3 as an optical waveguide, and a photoelectric conversion element 4. The flexible circuit board 2, optical waveguide film 3, and photoelectric conversion element 4 will be described in detail below.

[0046] 2) Flexible circuit board The flexible circuit board 2 has a flat strip shape extending along its longitudinal direction. The flexible circuit board 2 is arranged from one end to the other in the longitudinal direction of the photoelectric mixed-signal substrate 1. Furthermore, the flexible circuit board 2 is arranged from one end to the other in the width direction of the photoelectric mixed-signal substrate 1.

[0047] Furthermore, the flexible circuit board 2 is positioned on one side in the thickness direction of the optical waveguide film 3 (described later). More specifically, the flexible circuit board 2 is positioned so as to contact the entire surface on one side in the thickness direction of the undercladding layer 31 (described later) of the optical waveguide film 3 (described later).

[0048] The flexible circuit board 2 comprises a metal support substrate 21, a base insulating layer 22, a conductor layer 23, and a cover insulating layer 24, arranged in order from one side to the other in the thickness direction.

[0049] The metal support substrate 21 has a flat strip shape extending along its longitudinal direction. The metal support substrate 21 is positioned on one side in the thickness direction of the optical waveguide film 3 (described later). More specifically, the metal support substrate 21 is in contact with one side in the thickness direction of the underclad layer 31 (described later) without an adhesive layer in between.

[0050] The metal support substrate 21 is made of, for example, a metal. Examples of metals include 42 alloy, aluminum, copper-beryllium, phosphor bronze, copper, silver, and aluminum. From the viewpoint of ensuring excellent rigidity and toughness, stainless steel is preferred.

[0051] The metal support substrate 21 is provided with a plurality of through holes 25. More specifically, the through holes 25 include light-emitting through holes 25A corresponding to the light-emitting element 41 (described later) and light-receiving through holes 25B corresponding to the light-receiving element 42 (described later).

[0052] The light-emitting through-hole 25A is formed by machining the metal support substrate 21 through using a known method. The light-emitting through-hole 25A faces the light-emitting opening 43 (described later) of the light-emitting element 41 (described later) in the thickness direction. The light-emitting through-hole 25A also faces the light-emitting mirror 36A (described later) of the optical waveguide film 3 in the thickness direction.

[0053] The light-receiving through-hole 25B is formed by machining the metal support substrate 21 through using a known method. The light-receiving through-hole 25B faces the light-receiving opening 44 (described later) of the light-receiving element 42 (described later) in the thickness direction. The light-receiving through-hole 25B also faces the light-receiving mirror 36B (described later) of the optical waveguide film 3 in the thickness direction.

[0054] The thickness of the metal support substrate 21 is selected within a range that does not impede the flexibility of the flexible circuit board 2. For example, the thickness of the metal support substrate 21 is 3 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less.

[0055] The base insulating layer 22 has a flat strip shape extending along its longitudinal direction. The base insulating layer 22 is positioned on one side of the metal support substrate 21 in the thickness direction. In other words, the base insulating layer 22 is laminated on the metal support substrate 21 so as to contact the surface on one side of the metal support substrate 21 in the thickness direction.

[0056] The base insulating layer 22 is made of, for example, an insulating material. Examples of insulating materials include polyimide. The thickness of the base insulating layer 22 is set as appropriate.

[0057] The base insulating layer 22 is provided with a plurality of openings 26. More specifically, the openings 26 include an light-emitting side opening 26A corresponding to the light-emitting element 41 (described later) and a light-receiving side opening 26B corresponding to the light-receiving element 42 (described later).

[0058] The light-emitting opening 26A is formed by photolithography of the base insulating layer 22 using a known method. The light-emitting opening 26A faces the light-emitting port 43 (described later) of the light-emitting element 41 (described later) in the thickness direction. The light-emitting opening 26A also faces the light-emitting mirror 36A (described later) of the optical waveguide film 3 in the thickness direction.

[0059] The light-receiving aperture 26B is formed by photolithography of the base insulating layer 22 using a known method. The light-receiving aperture 26B faces the light-receiving opening 44 (described later) of the light-receiving element 42 (described later) in the thickness direction. The light-receiving aperture 26B also faces the light-receiving mirror 36B (described later) of the optical waveguide film 3 in the thickness direction.

[0060] The conductor layer 23 is positioned on one side in the thickness direction of the base insulating layer 22. In other words, the conductor layer 23 is laminated on the base insulating layer 22 so as to be in contact with the surface of the base insulating layer 22 on one side in the thickness direction.

[0061] The conductive layer 23 is made of, for example, a conductive material. Examples of conductive materials include copper. The thickness of the conductive layer 23 is set as appropriate.

[0062] The conductor layer 23 includes a wiring section 27 extending along the longitudinal direction and a terminal section 30 continuous with the wiring section 27.

[0063] The wiring section 27 includes an optical-to-electrical transmission wiring 28 and an electrical transmission wiring 29.

[0064] The optical-electrical transmission wiring 28 is wiring that transmits electrical signals that are converted into optical signals. The optical-electrical transmission wiring 28 is arranged between the external substrate 100 (i.e., the transmitting external substrate 101 and the receiving external substrate 102) and the photoelectric conversion element 4 (i.e., the light-emitting element 41 (described later) and the light-receiving element 42 (described later)).

[0065] More specifically, in Figure 1, the photoelectric mixed-signal substrate 1 is provided with two optical-electrical transmission lines 28. Hereafter, the two optical-electrical transmission lines 28 will be distinguished as optical-electrical transmission line 28A and optical-electrical transmission line 28B.

[0066] The optical-electrical transmission wiring 28A is positioned between the transmitting-side external board 101 and the light-emitting element 41 (described later) when connecting the photoelectric mixed-signal board 1 and the transmitting-side external board 101, and is connected to them. The optical-electrical transmission wiring 28A can input the electrical signal output from the transmitting-side external board 101 to the light-emitting element 41 (described later).

[0067] The optical-electrical transmission wiring 28B is positioned between the receiving external board 102 and the photodetector 42 (described later) when connecting the photoelectric mixed-signal board 1 and the receiving external board 102, and is connected to them. The optical-electrical transmission wiring 28B can input the electrical signal output from the photodetector 42 (described later) to the receiving external board 102.

[0068] The electrical transmission wiring 29 is wiring that transmits power and / or electrical signals directly (i.e., without converting them to optical signals) between the transmitting external board 101 and the receiving external board 102.

[0069] When connecting the photoelectric mixed-signal substrate 1 to the transmitting-side external substrate 101 and the receiving-side external substrate 102, the electrical transmission wiring 29 is positioned between the transmitting-side external substrate 101 and the receiving-side external substrate 102 and connected to them. More specifically, although not shown, the electrical transmission wiring 29 is routed to bypass the light-emitting element 41 (described later) and the light-receiving element 42 (described later), and is positioned to electrically connect the transmitting-side external substrate 101 and the receiving-side external substrate 102.

[0070] The terminal portion 30 is the junction point between the conductor layer 23, the external substrate 100, and the photoelectric conversion element 4. The terminal portion 30 is formed at both ends in the longitudinal direction of the wiring portion 27.

[0071] More specifically, the terminal portions 30 are formed at both longitudinal ends of the optical-electrical transmission wiring 28 and are exposed from the cover insulating layer 24 (described later). The optical-electrical transmission wiring 28 and the external substrate 100 are electrically connected via the terminal portions 30. In addition, the optical-electrical transmission wiring 28 and the photoelectric conversion element 4 (described later) are electrically connected via the terminal portions 30. Although not shown, terminal portions 30 are also formed at both longitudinal ends of the electrical transmission wiring 29 and are connected to the external substrate 100.

[0072] The cover insulating layer 24 has a flat strip shape extending along its longitudinal direction. The cover insulating layer 24 is positioned on one side of the conductor layer 23 in the thickness direction. In other words, the cover insulating layer 24 is laminated so as to be in contact with the surface of the conductor layer 23 on one side in the thickness direction.

[0073] More specifically, the cover insulating layer 24 is in contact with one side in the thickness direction of the base insulating layer 22 surrounding the wiring portion 27 so as to cover the wiring portion 27.

[0074] The cover insulating layer 24 is made of, for example, an insulating material. Examples of insulating materials include polyimide. The thickness of the cover insulating layer 24 is set as appropriate.

[0075] The thickness of the flexible circuit board 2 is not particularly limited and can be set as appropriate. For example, the thickness of the flexible circuit board 2 is 10 μm or more and 150 μm or less, preferably 15 μm or more and 100 μm or less.

[0076] 3) Optical waveguide film The optical waveguide film 3 has a long shape. More specifically, the optical waveguide film 3 has a flat strip shape extending along its longitudinal direction. The optical waveguide film 3 is arranged from one end to the other in the longitudinal direction of the photoelectric substrate 1. Furthermore, the optical waveguide film 3 is arranged from one end to the other in the width direction of the photoelectric substrate 1.

[0077] Furthermore, the optical waveguide film 3 is positioned on the other side in the thickness direction of the flexible circuit board 2. More specifically, the optical waveguide film 3 is positioned so as to contact the entire surface of the other side in the thickness direction of the metal support substrate 21 of the flexible circuit board 2.

[0078] The optical waveguide film 3 comprises a core layer 32 made of a core material and a cladding layer 34 made of a cladding material. The cladding layer 34 comprises an undercladding layer 31 located on one side in the thickness direction of the core layer 32 and an overcladding layer 33 located on the other side in the thickness direction of the core layer 32.

[0079] In other words, the optical waveguide film 3 comprises an undercladding layer 31, a core layer 32, and an overcladding layer 33, arranged in order from one side to the other in the thickness direction.

[0080] The undercladding layer 31 has a flat strip shape that extends along the longitudinal direction. The undercladding layer 31 is positioned to contact the surface of the flexible circuit board 2 on the other side in the thickness direction.

[0081] The underclad layer 31 is made of a cladding material. Examples of cladding materials include resins. Examples of resins include the photosensitive resins mentioned above, and preferably epoxy resins. Furthermore, the cladding material is preferably selected such that the refractive index of the underclad layer 31 is lower than that of the core layer 32. The specific refractive index of the underclad layer 31 is selected according to the purpose and application.

[0082] The thickness of the underclad layer 31 is, for example, 2 μm to 200 μm, preferably 3 μm to 100 μm, more preferably 4 μm to 75 μm, and even more preferably 5 μm to 50 μm.

[0083] The core layer 32 has a prismatic shape extending along its longitudinal direction. The core layer 32 has a roughly rectangular shape in cross-section. Multiple core layers 32 are arranged on the other side of the underclad layer 31 in the thickness direction, spaced apart in the width direction.

[0084] The core layer 32 is made of a core material. Examples of core materials include resins. Examples of resins include photosensitive resins. Examples of photosensitive resins include epoxy resins, acrylic resins, and silicone resins, with epoxy resin being preferred. Furthermore, the core material is preferably selected such that the refractive index of the core layer 32 is higher than that of the cladding layer 34. The specific refractive index of the core layer 32 is selected according to the purpose and application.

[0085] The thickness of the core layer 32 is, for example, 5 μm to 100 μm, preferably 10 μm to 90 μm, more preferably 15 μm to 80 μm, and even more preferably 20 μm to 60 μm.

[0086] In a plan view, the overcladding layer 33 is positioned at the same location as the undercladding layer 31. Specifically, the overcladding layer 33 is positioned on the other side of the undercladding layer 31 in the thickness direction, covering the other side of the core layer 32 in the thickness direction and both sides in the width direction.

[0087] The overcladding layer 33 is made of the cladding material described above. Preferably, the cladding material is selected such that the refractive index of the overcladding layer 33 is lower than that of the core layer 32.

[0088] The thickness of the overcladding layer 33 is, for example, 2 μm to 600 μm, preferably 3 μm to 100 μm, more preferably 4 μm to 60 μm, and even more preferably 5 μm to 45 μm.

[0089] The overcladding layer 33, together with the undercladding layer 31, forms the cladding layer 34. More specifically, the cladding layer 34 consists of the overcladding layer 33 and the undercladding layer 31.

[0090] The cladding layer 34 is arranged to surround the core layer 32 in the width and thickness directions perpendicular to the longitudinal direction. More specifically, the cladding layer 34 is arranged on one and the other side of the core layer 32 in the thickness direction, and also on one and the other side of the core layer 32 in the width direction.

[0091] Furthermore, the optical waveguide film 3 includes an intermediate layer 35 between the core layer 32 and the cladding layer 34. The intermediate layer 35 extends along the longitudinal direction.

[0092] The intermediate layer 35 is arranged to surround the core layer 32 in the width and thickness directions perpendicular to the longitudinal direction. More specifically, the intermediate layer 35 is arranged on one and the other side of the core layer 32 in the thickness direction, and also on one and the other side of the core layer 32 in the width direction.

[0093] The intermediate layer 35 contains a core material and a cladding material, and preferably consists of a core material and a cladding material. The intermediate layer 35 is positioned between the core layer 32 and the cladding layer 34. In other words, the intermediate layer 35 has a rectangular tubular shape surrounding the core layer 32, and the cladding layer 34 has a rectangular tubular shape surrounding the core layer 32 and the intermediate layer 35.

[0094] The method for obtaining the intermediate layer 35 is not particularly limited. For example, the intermediate layer 35 may be formed together with the core layer 32 and / or with the cladding layer 34.

[0095] More specifically, for example, first, an uncured cladding material is placed on the surface of the flexible circuit board 2 on the other side in the thickness direction and cured by a known method. As a result, an undercladding layer 31 made of the cladding material is formed. Next, an uncured core material is placed on the surface of the undercladding layer 31 on the other side in the thickness direction and cured by a known method. This forms a core layer 32 made of the core material. Then, an uncured cladding material is placed on the surface of the undercladding layer 31 on the other side in the thickness direction so as to cover the core layer 32 and cured by a known method. As a result, an overcladding layer 33 made of the cladding material is formed. Thus, the core layer 32 and the cladding layer 34 (undercladding layer 31 and overcladding layer 33) surrounding the core layer 32 are formed.

[0096] Furthermore, in the above method, when the underclad layer 31 and the uncured core material come into contact, the clad material and the core material are mixed at the contact area, forming a mixed layer. Also, in the above method, when the core layer 32 and the uncured clad material come into contact, the clad material and the core material are mixed at the contact area, forming a mixed layer. Then, as the mixed layer hardens, an intermediate layer 35 consisting of the core material and the clad material is formed. In other words, the intermediate layer 35 is formed between the core layer 32 and the clad layer 34. The intermediate layer 35 is arranged, for example, to surround the core layer 32. The clad layer 34 is also arranged to surround the core layer 32 and the intermediate layer 35. The content ratio of the core material and the clad material in the intermediate layer 35 are not particularly limited and are set as appropriate. The proportion of clad material in the intermediate layer 35 is, for example, greater than 0 mass%, preferably 50 mass% or more, relative to the total amount of core material and clad material. Furthermore, the proportion of cladding material in the intermediate layer 35 is, for example, less than 100% by mass, preferably 90% by mass or less, relative to the total amount of core material and cladding material. The proportion of cladding material in the intermediate layer 35 is calculated, for example, by Raman spectroscopy.

[0097] The refractive index of the intermediate layer 35 is, for example, between the refractive index of the underclad layer 31 and / or the overclad layer 33 and the refractive index of the core layer 32. The specific refractive index of the intermediate layer 35 is selected according to the purpose and application.

[0098] The thickness of the intermediate layer 35 is, for example, 0.01 μm or more and 10 μm or less, preferably 0.1 μm or more and 5 μm or less.

[0099] Furthermore, the core layer 32 of the optical waveguide film 3 is equipped with multiple mirrors 36. Each mirror 36 has an emitting-side mirror 36A corresponding to the light-emitting element 41 (described later) and a light-receiving-side mirror 36B corresponding to the light-receiving element 42 (described later). In other words, the core layer 32 is equipped with an emitting-side mirror 36A and a light-receiving-side mirror 36B.

[0100] The light-emitting mirror 36A converts the optical path of the light signal emitted from the light-emitting element 41 (described later) toward the core layer 32. The light-emitting mirror 36A is formed by machining the core layer 32 at a predetermined angle (for example, 45°).

[0101] The light-emitting mirror 36A and the light-emitting opening 43 (described later) of the light-emitting element 41 (described later) overlap in the thickness direction of the photoelectric mixed-signal substrate 1. From the viewpoint of transmission efficiency in optical transmission, the size of the light-emitting mirror 36A is set according to the size of the light-emitting opening 43 (described later). Details regarding the relationship between the size of the light-emitting mirror 36A and the size of the light-emitting opening 43 (described later) will be described later.

[0102] The light-receiving mirror 36B converts the optical path of the optical signal that has passed through the core layer 32 toward the light-receiving element 42 (described later). The light-receiving mirror 36B is formed by machining the core layer 32 at a predetermined angle (for example, 45°).

[0103] The light-receiving mirror 36B and the light-receiving aperture 44 (described later) of the light-receiving element 42 (described later) overlap in the thickness direction of the photoelectric mixed-signal substrate 1. From the viewpoint of transmission efficiency in optical transmission, the size of the light-receiving mirror 36B is set according to the size of the light-receiving aperture 44 (described later). Details regarding the relationship between the size of the light-receiving mirror 36B and the size of the light-receiving aperture 44 (described later) will be described later.

[0104] The thickness of the optical waveguide film 3 is not particularly limited and can be set as appropriate. For example, the thickness of the optical waveguide film 3 is 20 μm or more and 250 μm or less, preferably 50 μm or more and 150 μm or less.

[0105] 4) Photoelectric conversion element The photoelectric conversion element 4 is mounted on one side in the thickness direction of the flexible circuit board 2. The photoelectric conversion element 4 comprises a light-emitting element 41 and a light-receiving element 42. In other words, the photoelectric mixed-mount substrate 1 comprises a light-emitting element 41 and a light-receiving element 42.

[0106] The light-emitting element 41 is a photoelectric conversion element 4 for converting electrical signals into optical signals. The light-emitting element 41 is positioned on one side in the thickness direction of the flexible circuit board 2. The light-emitting element 41 converts the electrical signal output from the transmitting-side external board 101 into an optical signal and transmits the optical signal toward the light-emitting-side mirror 36A.

[0107] More specifically, the light-emitting element 41 is, for example, a surface-emitting light-emitting diode (VCSEL). The light-emitting element 41 is mounted on one side in the thickness direction and one side in the longitudinal direction of the flexible circuit board 2, near the transmitting external board 101.

[0108] The light-emitting element 41 is equipped with a light-emitting port 43 that transmits an optical signal toward the light-emitting mirror 36A. The light-emitting port 43 is, for example, an opening that opens toward the other side in the thickness direction of the light-emitting element 41. The light-emitting port 43 is located at the other end of the light-emitting element 41 in the thickness direction. The light-emitting port 43 is also opposite the light-emitting mirror 36A in the thickness direction of the photoelectric mixed-signal substrate 1.

[0109] More specifically, the entire projection surface obtained by projecting the light-emitting port 43 in the thickness direction of the photoelectric substrate 1 overlaps with a portion of the projection surface obtained by projecting the light-emitting side mirror 36A in the thickness direction of the photoelectric substrate 1. In the thickness direction of the photoelectric substrate 1, the projection surface of the light-emitting port 43 is positioned inside the projection surface of the light-emitting side mirror 36A.

[0110] Furthermore, in the light-emitting element 41 described above, the size of the light-emitting opening 43 is set according to the size of the light-emitting side mirror 36A. Details regarding the relationship between the size of the light-emitting side mirror 36A and the size of the light-emitting opening 43 will be described later.

[0111] The light-receiving element 42 is a photoelectric conversion element 4 for converting an optical signal into an electrical signal. The light-receiving element 42 is positioned on one side in the thickness direction of the flexible circuit board 2. The light-receiving element 42 receives the optical signal converted by the light-receiving mirror 36B and converts it into an electrical signal. It then outputs the electrical signal toward the receiving external board 102.

[0112] More specifically, the light-receiving element 42 is, for example, a photodiode. The light-receiving element 42 is mounted on one side of the flexible circuit board 2 in the thickness direction and on the other side in the longitudinal direction, near the receiving external board 102.

[0113] The light-receiving element 42 is equipped with a light-receiving port 44 that receives the optical signal converted by the light-receiving mirror 36B.

[0114] The light-receiving opening 44 is, for example, an opening that opens toward the other side in the thickness direction of the light-receiving element 42. The light-receiving opening 44 is located at the other end of the light-receiving element 42 in the thickness direction. The light-receiving opening 44 is also opposite the light-receiving side mirror 36B in the thickness direction of the photoelectric mixed-signal substrate 1.

[0115] More specifically, a portion of the projection surface obtained by projecting the light-receiving aperture 44 in the thickness direction of the photoelectric substrate 1 overlaps with the entire projection surface obtained by projecting the light-receiving mirror 36B in the thickness direction of the photoelectric substrate 1. Furthermore, in the thickness direction of the photoelectric substrate 1, the projection surface of the light-receiving mirror 36B is positioned inside the projection surface of the light-receiving aperture 44.

[0116] Furthermore, in the light-receiving element 42 described above, the size of the light-receiving aperture 44 is set according to the size of the light-receiving mirror 36B. Details regarding the relationship between the size of the light-receiving mirror 36B and the size of the light-receiving aperture 44 will be described later.

[0117] 5) Transmission of optical and electrical signals In the above-described photoelectric mixed-signal substrate 1, arbitrary information is transmitted as electrical signals and optical signals between the transmitting external substrate 101 and the receiving external substrate 102.

[0118] More specifically, arbitrary information is output as an electrical signal from the transmitting external board 101 and input to the light-emitting element 41 via the optical-electrical transmission wiring 28A. In the light-emitting element 41, the electrical signal is converted into an optical signal. The optical signal is transmitted from the light-emitting port 43 of the light-emitting element 41. The optical signal is converted by optical path conversion at the light-emitting mirror 36A. The optical path converted optical signal passes through the core layer 32 and is converted by optical path conversion again at the light-receiving mirror 36B. The optical path converted optical signal is then transmitted to the light-receiving port 44 of the light-receiving element 42. The light-receiving element 42 receives the optical signal from the light-receiving port 44 and converts it into an electrical signal. The electrical signal is then output from the light-receiving element 42 and input to the receiving external board 102 via the optical-electrical transmission wiring 28B. In this way, arbitrary information is transmitted from the transmitting external board 101 to the receiving external board 102 as an electrical signal and an optical signal.

[0119] Furthermore, in the photoelectric mixed-signal substrate 1 described above, power and / or electrical signals are transmitted between the transmitting external board 101 and the receiving external board 102. That is, in the photoelectric mixed-signal substrate 1 described above, for example, an electrical signal is output from the transmitting external board 101 and input to the receiving external board 102 via the electrical transmission wiring 29.

[0120] 6) Suppression of the decrease in optical transmission efficiency In the above-described photoelectric mixed-signal substrate 1, the size ratio of each component (hereinafter referred to as the size ratio) is set in order to suppress a decrease in optical transmission efficiency. The size ratio of each component will be described in detail below.

[0121] (1) Size ratio of the light-emitting mirror and the light-emitting port Figure 2 is a schematic plan view showing the light-emitting element and its surroundings in the photoelectric mixed-signal substrate shown in Figure 1, with other components omitted. Figure 2 shows the core layer 32, the intermediate layer 35, and the light-emitting element 41, with other components omitted.

[0122] In the above optical transmission, the optical signal is transmitted from the light-emitting element 41 toward the core layer 32 (specifically, the light-emitting mirror 36A). On the other hand, optical signals have the property of diffusing and / or scattering in the atmosphere. Therefore, in the above optical transmission, the optical signal may diffuse and / or scatter between the light-emitting element 41 and the core layer 32, resulting in loss of the optical signal and an increase in reflected light. To address this, in the above photoelectric mixed-signal substrate 1, as shown in Figure 2, the size ratio of the light-emitting aperture 43 and the light-emitting mirror 36A is adjusted.

[0123] More specifically, in the photoelectric mixed-mount substrate 1 described above, the widthwise length l1 of the light-emitting aperture 43 of the light-emitting element 41 is smaller than the widthwise length L1 of the light-emitting side mirror 36A.

[0124] The ratio (l1 / L1) of the widthwise length l1 of the light-emitting port 43 to the widthwise length L1 of the light-emitting mirror 36A is, for example, 0.03 or more, preferably 0.07 or more, and more preferably 0.1 or more. Also, the ratio (l1 / L1) of the widthwise length l1 of the light-emitting port 43 to the widthwise length L1 of the light-emitting mirror 36A is, for example, less than 1.0, preferably 0.9 or less, and more preferably 0.5 or less. That is, the ratio (l1 / L1) of the widthwise length l1 of the light-emitting port 43 to the widthwise length L1 of the light-emitting mirror 36A is, for example, 0.03 or more and less than 1.0, preferably 0.07 or more and 0.9 or less, and more preferably 0.1 or more and 0.5 or less.

[0125] Furthermore, in the photoelectric mixed-mount substrate 1 described above, the longitudinal length of the light-emitting opening 43 of the light-emitting element 41 is smaller than the longitudinal length of the light-emitting side mirror 36A.

[0126] The ratio of the longitudinal length of the light-emitting opening 43 to the longitudinal length of the light-emitting mirror 36A is, for example, 0.03 or more, preferably 0.07 or more, and more preferably 0.1 or more. Also, the ratio of the longitudinal length of the light-emitting opening 43 to the longitudinal length of the light-emitting mirror 36A is, for example, less than 1.0, preferably 0.9 or less, and more preferably 0.5 or less. That is, the ratio of the longitudinal length of the light-emitting opening 43 to the longitudinal length of the light-emitting mirror 36A is, for example, 0.03 or more and less than 1.0, preferably 0.07 or more and 0.9 or less, and more preferably 0.1 or more and 0.5 or less.

[0127] (2) Size ratio of the light-receiving mirror and light-receiving opening Figure 3 is a schematic plan view showing the photodetector and its surroundings in the photoelectric mixed-signal substrate shown in Figure 1. Figure 3 shows the core layer 32, the intermediate layer 35, and the photodetector 42, with other components omitted.

[0128] In the optical transmission described above, the optical signal is transmitted from the core layer 32 (specifically, the light-receiving mirror 36B) towards the light-receiving element 42. On the other hand, optical signals have the property of diffusing and / or scattering in the atmosphere. Therefore, in the optical transmission described above, the optical signal may diffuse and / or scatter between the core layer 32 and the light-receiving element 42, resulting in loss of the optical signal and an increase in reflected light. To address this, in the photoelectric mixed-signal substrate 1 described above, the size ratio of the light-receiving aperture 44 and the light-receiving mirror 36B is adjusted, as shown in Figure 3.

[0129] More specifically, in the photoelectric mixed-signal substrate 1 described above, the widthwise length l2 of the light-receiving aperture 44 of the light-receiving element 42 is greater than the widthwise length L2 of the light-receiving mirror 36B.

[0130] The ratio (l2 / L2) of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length L2 of the light-receiving mirror 36B is, for example, greater than 1.0, preferably 1.2 or more, and more preferably 1.4 or more. Also, the ratio (l2 / L2) of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length L2 of the light-receiving mirror 36B is, for example, 2.2 or less, preferably 2.0 or less, and more preferably 1.8 or less. That is, the ratio (l2 / L2) of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length L2 of the light-receiving mirror 36B is, for example, greater than 1.0 and 2.2 or less, preferably 1.2 or more and 2.0 or less, and more preferably 1.4 or more and 1.8 or less.

[0131] Furthermore, in the photoelectric mixed-signal substrate 1 described above, the longitudinal length of the light-receiving aperture 44 of the light-receiving element 42 is smaller than the longitudinal length of the light-receiving mirror 36B.

[0132] The ratio of the longitudinal length of the light-receiving aperture 44 to the longitudinal length of the light-receiving mirror 36B is, for example, greater than 1.0, preferably 1.2 or more, and more preferably 1.4 or more. Also, the ratio of the longitudinal length of the light-receiving aperture 44 to the longitudinal length of the light-receiving mirror 36B is, for example, 2.2 or less, preferably 2.0 or less, and more preferably 1.8 or less. That is, the ratio of the longitudinal length of the light-receiving aperture 44 to the longitudinal length of the light-receiving mirror 36B is, for example, greater than 1.0 and 2.2 or less, preferably 1.2 or more and 2.0 or less, and more preferably 1.4 or more and 1.8 or less.

[0133] (3) Size ratio of the core layer and the intermediate layer In the transmission of the optical signal described above, the optical signal is converted by the mirror 36 of the core layer 32. Therefore, in the photoelectric mixed-signal substrate 1 described above, the size ratio of the core layer 32 and the intermediate layer 35 is adjusted.

[0134] More specifically, when the size of the intermediate layer 35 is relatively small and the size of the core layer 32 is relatively large, excellent optical transmission efficiency can be obtained. On the other hand, making the size of the intermediate layer 35 relatively small is labor-intensive and may lead to a decrease in productivity. Also, when the size of the intermediate layer 35 is relatively large and the size of the core layer 32 is relatively small, excellent productivity can be obtained. On the other hand, making the size of the intermediate layer 35 relatively large may lead to a decrease in optical transmission efficiency.

[0135] Therefore, in the above-described photoelectric mixed-signal substrate 1, from the viewpoint of achieving both transmission efficiency in optical transmission and production efficiency and workability, the ratio of the widthwise length L of the core layer 32 to the sum of the widthwise length of the core layer 32, the widthwise length of the intermediate layer 35 located on one side of the widthwise direction of the core layer 32, and the widthwise length of the intermediate layer 35 located on the other side of the widthwise direction of the core layer 32 (i.e., the sum of the widthwise lengths of the core layer 32 and the intermediate layer 35) L0 is adjusted.

[0136] For example, the ratio of the widthwise length L of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L / L0) is, for example, 0.4 or more, preferably 0.6 or more. Also, the ratio of the widthwise length L of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L / L0) is, for example, less than 1.0, preferably 0.9 or less. That is, the ratio of the widthwise length L of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L / L0) is, for example, 0.4 or more and less than 1.0, preferably 0.6 or more and 0.9 or less.

[0137] In particular, in the light-emitting mirror 36A, the intermediate layer 35 is relatively large, and the core layer 32 is relatively small. More specifically, in the light-emitting mirror 36A, the ratio of the widthwise length L1 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L1 / L0) is, for example, 0.4 or more, preferably 0.6 or more. Also, in the light-emitting mirror 36A, the ratio of the widthwise length L1 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L1 / L0) is, for example, less than 1.0, preferably 0.9 or less. That is, in the light-emitting mirror 36A, the ratio of the widthwise length L1 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L1 / L0) is, for example, 0.4 or more and less than 1.0, preferably 0.6 or more and 0.9 or less.

[0138] On the other hand, in the light-receiving mirror 36B, the intermediate layer 35 is relatively small, and the core layer 32 is relatively large. More specifically, in the light-receiving mirror 36B, the ratio of the widthwise length L2 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L2 / L0) is, for example, 0.7 or more, preferably 0.9 or more. Also, in the light-receiving mirror 36B, the ratio of the widthwise length L2 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L2 / L0) is, for example, less than 1.0, preferably 0.95 or less. That is, in the light-receiving mirror 36B, the ratio of the widthwise length L2 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 (L2 / L0) is, for example, 0.7 or more and less than 1.0, preferably 0.9 or more and 0.95 or less.

[0139] Furthermore, the difference between the ratio of the width direction length L2 of the core layer 32 to the sum of the width direction lengths L0 of the core layer 32 and the intermediate layer 35 in the light-receiving mirror 36B (L2 / L0) and the ratio of the width direction length L1 of the core layer 32 to the sum of the width direction lengths L0 of the core layer 32 and the intermediate layer 35 in the light-emitting mirror 36A (L1 / L0) is, for example, 0.1 or more, preferably 0.2 or more. Also, the difference between the ratio of the width direction length L2 of the core layer 32 to the sum of the width direction lengths L0 of the core layer 32 and the intermediate layer 35 in the light-receiving mirror 36B (L2 / L0) and the ratio of the width direction length L1 of the core layer 32 to the sum of the width direction lengths L0 of the core layer 32 and the intermediate layer 35 in the light-emitting mirror 36A (L1 / L0) is, for example, 0.8 or less, preferably 0.5 or less. In other words, the difference between the ratio of the widthwise length L2 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 in the light-receiving mirror 36B and the ratio of the widthwise length L2 of the core layer 32 to the sum of the widthwise lengths L0 of the core layer 32 and the intermediate layer 35 in the light-emitting mirror 36A is, for example, 0.1 or more and 0.8 or less, preferably 0.2 or more and 0.5 or less.

[0140] (4) Size ratio of light-emitting port and light-receiving port In the photoelectric mixed-signal substrate 1 described above, the widthwise length l2 of the light-receiving aperture 44 of the light-receiving element 42 is greater than the widthwise length l1 of the light-emitting aperture 43 of the light-emitting element 41.

[0141] For example, the ratio of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length l1 of the light-emitting aperture 43 (l2 / l1) is, for example, 3 or more, preferably 4 or more, and more preferably 5 or more. Also, the ratio of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length l1 of the light-emitting aperture 43 (l2 / l1) is, for example, 10 or less, preferably 8 or less. That is, the ratio of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length l1 of the light-emitting aperture 43 (l2 / l1) is, for example, 3 or more and 10 or less, preferably 4 or more and 8 or less.

[0142] (5) Size ratio of the light-emitting mirror and the light-receiving mirror In the above-described photoelectric mixed-signal substrate 1, the ratio of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is not particularly limited.

[0143] For example, the ratio (L2 / L1) of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is, for example, 0.8 or more, preferably 0.9 or more, and more preferably 0.95 or more. Also, the ratio (L2 / L1) of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is, for example, 1.2 or less, preferably 1.1 or less, and more preferably 1.05 or less. That is, the ratio (L2 / L1) of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is, for example, 0.8 or more and 1.2 or less, preferably 0.9 or more and 1.1 or less, and more preferably 0.95 or more and 1.05 or less. Particularly preferable is that the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A and the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B are the same.

[0144] (6) Shape of the light-emitting mirror and the light-receiving mirror From the viewpoint of improving optical transmission efficiency, in the above-described photoelectric mixed-signal substrate 1, the reflective surface of the light-emitting mirror 36A has a curved shape, as shown in the partially enlarged view of Figure 1. More specifically, the reflective surface of the light-emitting mirror 36A has a light-emitting curved surface 38A that is recessed from one side to the other in the longitudinal direction of the core layer 32. The light-emitting curved surface 38A is formed by machining the core layer 32 using a known method.

[0145] The curvature of the light-emitting curved surface 38A is, for example, 50 or more, preferably 100 or more, and more preferably 200 or more. Alternatively, the curvature of the light-emitting curved surface 38A is, for example, 1000 or less, preferably 900 or less, and more preferably 800 or less. In other words, the curvature of the light-emitting curved surface 38A is, for example, 50 or more and 1000 or less, preferably 100 or more and 900 or less, and more preferably 200 or more and 800 or less.

[0146] Furthermore, from the viewpoint of improving optical transmission efficiency, in the above-described photoelectric mixed-signal substrate 1, the reflective surface of the light-receiving mirror 36B has a curved shape, as shown in the partially enlarged view of Figure 1. More specifically, the reflective surface of the light-receiving mirror 36B has a light-receiving curved surface 38B that bulges from one side to the other side in the longitudinal direction of the core layer 32. The light-receiving curved surface 38B is formed by machining the core layer 32 using a known method.

[0147] The curvature of the light-receiving surface 38B is, for example, 50 or more, preferably 100 or more, and more preferably 200 or more. Alternatively, the curvature of the light-receiving surface 38B is, for example, 1000 or less, preferably 900 or less, and more preferably 800 or less. In other words, the curvature of the light-receiving surface 38B is, for example, 50 or more and 1000 or less, preferably 100 or more and 900 or less, and more preferably 200 or more and 800 or less.

[0148] 7) Effects The above-described photoelectric mixed-signal substrate 1 comprises a flexible circuit board 2, an optical waveguide film 3, and a photodetector 42. The optical waveguide film 3 comprises a core layer 32 made of a core material and equipped with a photodetector-side mirror 36B, a cladding layer 34 made of a cladding material, and an intermediate layer 35 containing the core material and the cladding material.

[0149] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the widthwise length l2 of the light-receiving aperture 44 of the light-receiving element 42 is greater than the widthwise length L2 of the light-receiving side mirror 36B of the core layer 32.

[0150] Therefore, in the above-described photoelectric mixed-signal substrate 1, even when the optical signal reflected at the light-receiving mirror 36B of the core layer 32 is diffused and / or scattered, the optical signal is efficiently received at the relatively large light-receiving aperture 44. As a result, the above-described photoelectric mixed-signal substrate 1 enables efficient optical transmission.

[0151] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the size of the light-receiving mirror 36B and the size of the light-receiving aperture 44 are adjusted so that the ratio (l2 / L2) of the width direction length l2 of the light-receiving aperture 44 to the width direction length L2 of the light-receiving mirror 36B exceeds a predetermined value. Therefore, the above-described photoelectric mixed-signal substrate 1 can further suppress the decrease in optical transmission efficiency.

[0152] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the curvature of the light-receiving curved surface of the light-receiving mirror 36B is adjusted to a predetermined value or higher. Therefore, the above-described photoelectric mixed-signal substrate 1 can improve the optical transmission efficiency.

[0153] Furthermore, the photoelectric mixed substrate 1 described above includes a light-emitting element 41, and the optical waveguide film 3 is made of a core material and includes a light-emitting side mirror 36A. In the photoelectric mixed substrate 1 described above, the widthwise length l1 of the light-emitting opening 43 of the light-emitting element 41 is smaller than the widthwise length L1 of the light-emitting side mirror 36A of the core layer 32.

[0154] Therefore, in the above-described photoelectric mixed substrate 1, even when the optical signal emitted from the light-emitting element 41 is diffused and / or scattered, it is efficiently reflected by the relatively large light-emitting side mirror 36A. As a result, the above-described photoelectric mixed substrate 1 can further suppress the decrease in optical transmission efficiency.

[0155] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the size of the light-emitting mirror 36A and the size of the light-emitting aperture 43 are adjusted so that the ratio (l1 / L1) of the width direction length l1 of the light-emitting aperture 43 to the width direction length L1 of the light-emitting mirror 36A falls within a predetermined range. Therefore, the above-described photoelectric mixed-signal substrate 1 can further suppress the decrease in optical transmission efficiency.

[0156] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the curvature of the light-emitting side curved surface of the light-emitting side mirror 36A is adjusted to a predetermined value or higher. Therefore, the above-described photoelectric mixed-signal substrate 1 can improve the optical transmission efficiency.

[0157] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the size of the core layer 32 and the size of the intermediate layer 35 are adjusted so that the ratio of the widthwise length L of the core layer 32 to the sum of the widthwise length of the core layer 32, the widthwise length of the intermediate layer 35 located on one side of the widthwise direction of the core layer 32, and the widthwise length of the intermediate layer 35 located on the other side of the widthwise direction of the core layer 32 (i.e., the sum of the widthwise lengths of the core layer 32 and the intermediate layer 35) L0 is greater than or equal to a predetermined value. Therefore, the above-described photoelectric mixed-signal substrate 1 can further suppress the decrease in optical transmission efficiency.

[0158] Furthermore, in the photoelectric mixed-signal substrate 1 described above, the size of the core layer 32 and the intermediate layer 35 are adjusted so that the ratio of the width direction length L2 of the core layer 32 to the sum of the width direction lengths L0 of the core layer 32 and the intermediate layer 35 (L2 / L0) is greater than or equal to a predetermined value in the light-receiving mirror 36B. Therefore, the decrease in optical transmission efficiency can be further suppressed with the photoelectric mixed-signal substrate 1 described above.

[0159] Furthermore, in the photoelectric mixed-signal substrate 1 described above, the size of the core layer 32 and the size of the intermediate layer 35 are adjusted so that the ratio of the width direction length L1 of the core layer 32 to the sum of the width direction lengths L0 of the core layer 32 and the intermediate layer 35 (L1 / L0) is greater than or equal to a predetermined value in the light-emitting side mirror 36A. Therefore, the decrease in optical transmission efficiency can be further suppressed with the photoelectric mixed-signal substrate 1 described above.

[0160] Furthermore, in the above-described photoelectric mixed-signal substrate 1, the size of the core layer 32 and the size of the intermediate layer 35 are adjusted so that the difference between the ratio of widthwise lengths (L2 / L0) in the light-receiving mirror 36B and the ratio of widthwise lengths (L1 / L0) in the light-emitting mirror 36A is greater than or equal to a predetermined value. Therefore, the above-described photoelectric mixed-signal substrate 1 can further suppress the decrease in optical transmission efficiency.

[0161] 2. Variations In the following modifications, the same reference numerals are used for components and processes as in the above-described embodiment, and their detailed descriptions are omitted. Furthermore, each modification can achieve the same effects as the above-described embodiment. Moreover, the above-described embodiment and its modifications can be combined as appropriate.

[0162] Figure 4 is a schematic plan view showing an enlarged view of the light-emitting element 41 and its surroundings in another embodiment of the photoelectric mixed-signal substrate 1 (a configuration in which the reflective surface of the light-emitting mirror 36A is roughened). Figure 4 shows the core layer 32, intermediate layer 35, light-emitting element 41, and composite member 39, while other members are omitted.

[0163] As shown in Figure 4, the optical waveguide film 3 may further comprise a composite member 39. The composite member 39 contains a core material and a cladding material, and preferably consists of a core material and a cladding material. The composite member 39 is, for example, the same as the intermediate layer 35.

[0164] The composite member 39 has any shape. The shape of the composite member 39 may be, for example, plate-like, granular, or lumpy. The size of the composite member 39 is not particularly limited and can be set as appropriate.

[0165] The composite member 39 is positioned on the reflective surface of the light-emitting mirror 36A. That is, the composite member 39 is in contact with the reflective surface of the light-emitting mirror 36A, and the reflective surface of the light-emitting mirror 36A is roughened by the composite member 39. The method of positioning the composite member 39 on the reflective surface of the light-emitting mirror 36A is not particularly limited and can be selected as appropriate.

[0166] Furthermore, in the above-described photoelectric composite substrate 1, the reflective surface of the light-emitting mirror 36A is roughened. That is, the optical signal is easily diffusely reflected by the light-emitting mirror 36A. Therefore, with the above-described photoelectric composite substrate 1, it is possible to suppress the optical signal from returning from the light-emitting mirror 36A to the light-emitting port 43 of the light-emitting element 41. As a result, the above-described photoelectric composite structure can suppress the generation of reflected light more efficiently. In other words, the above-described photoelectric composite structure can further suppress the decrease in optical transmission efficiency.

[0167] Figure 5 is a schematic plan view of another embodiment of the photoelectric mixed-signal substrate 1 (in which the widthwise length of the core layer 32 decreases from the other side of the longitudinal direction toward the one side of the longitudinal direction). Figure 5 shows the core layer 32, intermediate layer 35, light-emitting element 41, and light-receiving element 42, with other components omitted.

[0168] As shown in Figure 5, in the photoelectric mixed-signal substrate 1, the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A (see Figure 2) and the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B (see Figure 3) may be different from each other.

[0169] More specifically, in Figure 5, the core layer 32 has a substantially tapered shape in plan view. More specifically, in Figure 5, the widthwise length of the core layer 32 decreases from the other side in the longitudinal direction to the one side in the longitudinal direction. That is, the core layer 32 is formed to become narrower from the light-emitting mirror 36A to the light-receiving mirror 36B.

[0170] In other words, in the above-described photoelectric mixed-signal substrate 1, the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B (see Figure 3) is smaller than the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A (see Figure 2).

[0171] In the above-described photoelectric mixed substrate 1, the ratio (L2 / L1) of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is, for example, 0.5 or more, preferably 0.6 or more, and more preferably 0.7 or more. Also, the ratio (L2 / L1) of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is, for example, less than 1.0, preferably 0.9 or less, and more preferably 0.8 or less. That is, the ratio (L2 / L1) of the widthwise length L2 of the core layer 32 in the light-receiving mirror 36B to the widthwise length L1 of the core layer 32 in the light-emitting mirror 36A is, for example, 0.5 or more and less than 1.0, preferably 0.6 or more and 0.9 or less, and more preferably 0.7 or more and 0.8 or less.

[0172] Furthermore, in the above-described photoelectric mixed-mount substrate 1, the ratio of the widthwise length l1 of the light-emitting aperture 43 of the light-emitting element 41 (see Figure 2) to the widthwise length l2 of the light-receiving aperture 44 of the light-receiving element 42 (see Figure 3) is not particularly limited.

[0173] For example, the ratio of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length l1 of the light-emitting aperture 43 (l2 / l1) is, for example, 0.8 or more, preferably 0.9 or more, and more preferably 0.95 or more. Also, the ratio of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length l1 of the light-emitting aperture 43 (l2 / l1) is, for example, 1.2 or less, preferably 1.1 or less, and more preferably 1.05 or less. That is, the ratio of the widthwise length l2 of the light-receiving aperture 44 to the widthwise length l1 of the light-emitting aperture 43 (l2 / l1) is, for example, 0.8 or more and 1.2 or less, preferably 0.9 or more and 1.1 or less, and more preferably 0.95 or more and 1.05 or less. Particularly preferably, in the above photoelectric mixed substrate 1, the widthwise length l1 of the light-emitting aperture 43 and the widthwise length l2 of the light-receiving aperture 44 are the same.

[0174] Furthermore, in the above-described photoelectric composite substrate 1, the widthwise length of the core layer 32 decreases as it moves from the other side in the longitudinal direction toward the one side in the longitudinal direction. In addition, in the above-described photoelectric composite structure, the size of the core layer 32 is adjusted so that the ratio of the widthwise length L1 of the core layer 32 at the light-emitting mirror 36A to the widthwise length L2 of the core layer 32 at the light-receiving mirror 36B is within a predetermined range. Therefore, the above-described photoelectric composite substrate 1 can suppress a decrease in optical transmission efficiency.

[0175] 3. Active Optical Cable The photoelectric integrated substrate 1 described above is suitably used in the field of electronic equipment. More specifically, the photoelectric integrated substrate 1 is suitably used as an active optical cable, although it is not shown in the figures. That is, the active optical cable preferably comprises the photoelectric integrated substrate 1 described above.

[0176] Examples of active optical cables include film-type active optical cables. The active optical cable is connected between any external substrates 100 in a known manner. The active optical cable then transmits optical signals between the external substrates 100.

[0177] Since the above-described active optical cable includes the above-described photoelectric mixed-signal substrate 1, a decrease in optical transmission efficiency can be suppressed. [Explanation of Symbols]

[0178] 1. Photoelectric mixed-signal substrate 2 Flexible circuit board 3 Optical waveguide film 4. Photoelectric conversion element 21 Metal support substrate 22 Base insulating layer 23 Conductor layer 24 Cover insulation layer 25 Through holes 25A Light-emitting side through hole 25B Receiving side through hole 26 Opening 26A Light-emitting side aperture 26B Receiving side aperture 27 Wiring section 28 Optical-to-electrical transmission wiring 28a Optical-to-electrical transmission wiring 28b Optical-to-electrical transmission wiring 29 Electrical transmission wiring 30 Terminal section 31 Underclad Layer 32 core layers 33 Overclad layer 34 Clad Layer 35 Middle Class 36 Mirror 36A Light-emitting mirror 36B Receiver-side mirror 38A Light-emitting side curved surface 38B Receiving side curved surface 39 Composite Members 41 Light-emitting element 42 Photodetector 43 Light-emitting port 44 Light receiving port 101 Transmitter-side external board 102 Receiving side external board

Claims

1. It is a photoelectric composite structure having an elongated shape, The aforementioned photoelectric composite structure comprises an electrical circuit board, an optical waveguide, and a photodetector. The aforementioned electrical circuit board is arranged on one side in the thickness direction of the optical waveguide, The optical waveguide is, It consists of a core material, with a core layer extending along the longitudinal direction, A cladding material comprising a cladding layer arranged to surround the core layer in the width and thickness directions perpendicular to the longitudinal direction, An intermediate layer comprising the core material and the cladding material, and disposed between the core layer and the cladding layer Equipped with, The core layer includes a light-receiving mirror that converts the optical path of the optical signal toward the light-receiving element. The light-receiving element is mounted on the electrical circuit board and has a light-receiving port that receives the optical signal whose optical path has been converted by the light-receiving mirror. The light-receiving port and the light-receiving mirror overlap in the thickness direction of the photoelectric composite structure. A photoelectric composite structure in which the widthwise length of the light-receiving aperture is greater than the widthwise length of the light-receiving mirror.

2. The photoelectric composite structure according to claim 1, wherein the ratio of the widthwise length of the light-receiving aperture to the widthwise length of the light-receiving mirror exceeds 1.

0.

3. The reflective surface of the light-receiving mirror has a light-receiving curved surface that bulges from the other side in the longitudinal direction of the core layer toward the one side in the longitudinal direction. The photoelectric composite structure according to claim 1, wherein the curvature of the light-receiving curved surface is 100 or more.

4. Furthermore, it is equipped with a light-emitting element, The core layer includes a light-emitting side mirror that converts the optical path of the optical signal emitted from the light-emitting element, The light-emitting element is It is equipped with a light-emitting port that transmits a light signal toward the light-emitting side mirror, The light-emitting port and the light-emitting side mirror overlap in the thickness direction of the photoelectric composite structure. The photoelectric composite structure according to claim 1, wherein the widthwise length of the light-emitting opening is smaller than the widthwise length of the light-emitting mirror.

5. The photoelectric composite structure according to claim 4, wherein the ratio of the widthwise length of the light-emitting opening to the widthwise length of the light-emitting mirror is 0.9 or less.

6. The photoelectric composite structure according to claim 5, wherein the ratio of the widthwise length of the light-emitting opening to the widthwise length of the light-emitting mirror is 0.1 or more and 0.5 or less.

7. The reflective surface of the light-emitting mirror has a light-emitting curved surface that is recessed from one side to the other in the longitudinal direction of the core layer, The photoelectric composite structure according to claim 4, wherein the curvature of the light-emitting curved surface is 100 or more.

8. The widthwise length of the core layer and, The widthwise length of the intermediate layer, which is arranged on one side in the widthwise direction of the core layer, The widthwise length of the intermediate layer, which is arranged on the other side of the widthwise direction of the core layer, For the total, The width of the core layer The photoelectric composite structure according to claim 4, wherein the ratio is 0.6 or more.

9. In the light-receiving mirror, The widthwise length of the core layer and, The widthwise length of the intermediate layer, which is arranged on one side in the widthwise direction of the core layer, The widthwise length of the intermediate layer, which is arranged on the other side of the widthwise direction of the core layer, For the total, The width of the core layer The photoelectric composite structure according to claim 4, wherein the ratio is 0.9 or greater.

10. In the aforementioned light-emitting mirror, The widthwise length of the core layer and, The widthwise length of the intermediate layer, which is arranged on one side in the widthwise direction of the core layer, The widthwise length of the intermediate layer, which is arranged on the other side of the widthwise direction of the core layer, For the total, The photoelectric composite structure according to claim 4, wherein the ratio of the widthwise length of the core layer is 0.6 or more.

11. The ratio of the widthwise length of the core layer to the sum of the widthwise lengths of the intermediate layer located on one side of the core layer in the widthwise direction and the widthwise length of the intermediate layer located on the other side of the core layer in the widthwise direction, in the light-receiving mirror. and, In the light-emitting mirror, the ratio of the width of the core layer to the sum of the width of the intermediate layer located on one side of the core layer in the width direction and the width of the intermediate layer located on the other side of the core layer in the width direction. The photoelectric composite structure according to claim 10, wherein the difference between the two is 0.2 or more.

12. A composite member containing the core material and the cladding material is placed on the reflective surface of the light-emitting mirror. The photoelectric composite structure according to claim 4, wherein the reflective surface of the light-emitting mirror is roughened by the composite member.

13. With respect to the widthwise length of the core layer in the light-emitting mirror, The photoelectric composite structure according to claim 4, wherein the ratio of the widthwise length of the core layer in the light-receiving mirror is 0.5 or more and less than 1.

0.

14. The photoelectric composite structure according to claim 12, wherein the widthwise length of the core layer decreases as it moves from the other longitudinal side toward the one longitudinal side.

15. An active optical cable comprising a photoelectric composite structure according to any one of claims 1 to 14.

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