Optical-electric hybrid substrate, photoelectric conversion module, optical communication device, and electronic apparatus

Abstract

To provide an optical-electric hybrid substrate to achieve thinning while improving transmission speed.SOLUTION: An optical-electric hybrid substrate 1 includes, toward one side in the thickness direction, an optical waveguide 2 and an electric circuit substrate 3. The electric circuit substrate 3 includes, toward one side in the thickness direction, a metal support substrate 4, a base insulating layer 5, and a conductor layer 6. The metal support substrate 4 includes an island part 41 positioned between a second terminal 62 and a third terminal 63 in the longitudinal direction, and the island part 41 is spaced apart from its surroundings. The conductor layer 6 includes a first via 51, a second via 52, and an intermediate conductor part 16, and the intermediate conductor part 16 is positioned between the first via 51 and the second via 52 on the island part 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optoelectronic hybrid board, an optoelectronic conversion module, an optical communication device, and an electronic device. [Background technology]

[0002] Conventionally, there has been known an optical-electrical composite transmission module that includes an optical-electrical hybrid board including an optical waveguide and an electric circuit board, and an optical element and a driving element mounted on the upper surface of the board (see, for example, Patent Document 1 below). Such an optical-electrical composite transmission module is placed at one end or the other end of an optical communication line and converts between electrical signals and optical signals. Optical communication lines are capable of transmitting large amounts of information at high speeds without degradation, compared to electric communication lines. For this reason, optical-electrical composite transmission modules are being implemented in a variety of devices in a wide range of fields. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-63921 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the dramatic increase in transmission speeds in such optical-electrical integrated transmission modules has led to a demand for greater flexibility in the design of wiring on electrical circuit boards. Furthermore, the increasing use of these modules in compact devices such as smartphones has led to a demand for thinner modules.

[0005] To meet the demand for greater freedom in wiring design, the use of multi-layered electric circuit boards has been considered. However, multi-layered electric circuit boards increase the distance between the optical elements mounted on the electric circuit board and the core of the optical waveguide, resulting in loss in optical transmission.

[0006] The present invention provides an optoelectronic hybrid substrate that can improve transmission speed while being made thinner, an optoelectronic conversion module including the optoelectronic hybrid substrate, an optical communication device including the optoelectronic conversion module, and an optical apparatus including the optoelectronic conversion module. [Means for solving the problem]

[0007] The present invention [1] is an optoelectronic hybrid board having an optical waveguide and an electric circuit board in one thickness direction, the optical waveguide having an overclad, a core, and an underclad in the one thickness direction, the electric circuit board having a metal supporting substrate, an insulating layer, and a conductor layer in the one thickness direction, the conductor layer having a plurality of first terminals for electrically connecting to a light receiving element or a light emitting element, a plurality of second terminals for electrically connecting to a driving element or an amplifying element, a plurality of third terminals for electrically connecting to an external substrate, and a plurality of terminals for electrically connecting the second terminals and the third terminals. the first terminal, the second terminal, and the third terminal are spaced apart from each other and arranged in order toward one side of a longitudinal direction of the electric circuit board; the metal supporting board has an island portion arranged between the second terminal and the third terminal in the longitudinal direction, the island portion being spaced apart from the periphery so as to be electrically insulated from the periphery of the island portion; the insulating layer has a first through hole and a second through hole that are spaced apart from each other and penetrate the thickness direction at a position overlapping with the island portion in the thickness direction; the conductor layer further has a first via filled in the first through hole, a second via filled in the second through hole, and an intermediate conductor portion; the plurality of wirings include a first wiring electrically connected to the first via and a second wiring electrically connected to the second via, and the intermediate conductor portion is arranged between the first via and the second via.

[0008] In the above-mentioned optoelectronic hybrid board, the metal supporting board includes an island portion disposed between the second terminal and the third terminal in the longitudinal direction, the island portion being spaced apart from its surroundings so as to be electrically insulated from the surroundings of the island portion. In the above-mentioned optoelectronic hybrid board, the first wiring is connected to the island portion through the first via, and the second wiring is connected to the island portion through the second via. Therefore, an electrical signal transmitted through the first wiring is transmitted to the second wiring via the first via, the island portion, and the second via. Meanwhile, the intermediate conductor portion is disposed between the first via and the second via. Therefore, the space between the second terminal and the third terminal can be utilized to increase the degree of freedom in designing the conductor layer. Moreover, the island portion is provided on the metal supporting board. Therefore, the degree of freedom in designing the conductor layer can be increased without multi-layering the electric circuit board, thereby reducing the thickness and suppressing optical transmission loss, thereby improving transmission speed.

[0009] The present invention [2] includes the optoelectronic hybrid substrate according to the above [1], wherein the metal supporting board has a groove between the island portion and the periphery, and the groove is filled with resin.

[0010] In the above-mentioned optoelectronic hybrid board, the metal supporting board has a groove between the island portion and the periphery, and the groove is filled with resin. Therefore, it is possible to improve the insulation of the island portion from the periphery. Furthermore, by filling the groove with resin, it is possible to improve the adhesion of the island portion to the underclad and the electric circuit board.

[0011] The present invention [3] includes the optoelectronic hybrid substrate according to the above [2], in which the resin is the same as the material of the underclad.

[0012] In the above-described photoelectric hybrid substrate, since the resin is the same as the material of the underclad, the resin filled in the grooves is integrated with the underclad, and the adhesion of the island portion to the underclad can be further improved.

[0013] The present invention [4] includes the optoelectronic hybrid board according to the above [2], in which the resin is the same as the material of the insulating layer.

[0014] In the above optoelectronic hybrid board, the resin is the same material as the insulating layer, so that the insulating properties of the island portion can be further improved.

[0015] The present invention [5] includes the optoelectronic hybrid substrate according to the above [1], wherein one end of the core in the longitudinal direction is located on the other side of the island portion in the longitudinal direction.

[0016] In the optoelectronic hybrid board, one longitudinal end of the core is located on the other longitudinal side of the island portion, i.e., the island portion and the core do not overlap in the thickness direction of the optoelectronic hybrid board.

[0017] Therefore, the island portion can be designed independently of the optical transmission in the core, and the degradation of the optical signal due to the island portion can be prevented.

[0018] The present invention [6] includes the optoelectronic hybrid substrate described in [1] above, wherein the conductor layer includes a third wiring including the intermediate conductor portion, the third wiring including at least one of a differential wiring and a clock wiring, and the first wiring and the second wiring include signal wiring other than the differential wiring and the clock wiring.

[0019] In the above-mentioned optoelectronic hybrid board, by using the differential wiring or clock wiring, which requires accurate transmission, as the third wiring, accurate transmission can be ensured, while by using the other wiring as the first wiring and second wiring that pass through the island portion, the degree of freedom in wiring design can be increased.

[0020] The present invention [7] includes a photoelectric conversion module comprising the photoelectric hybrid substrate described in any one of [1] to [6] above, at least one of a light receiving element and a light emitting element electrically connected to the plurality of first terminals, at least one of a driving element and an amplifying element electrically connected to the plurality of second terminals, and an external substrate electrically connected to the plurality of third terminals.

[0021] Since the opto-electrical conversion module includes the opto-electrical hybrid board, the transmission speed can be improved while the thickness of the opto-electrical conversion module can be reduced.

[0022] The present invention [8] includes an optical communication device comprising the photoelectric conversion module according to the above [7] and an optical transmission line connected to the photoelectric conversion module.

[0023] Since the optical communication device includes the photoelectric conversion module, the transmission speed can be improved while the optical communication device is made smaller.

[0024] The present invention [9] includes an electronic device equipped with the photoelectric conversion module described in [7] above.

[0025] Since the electronic device includes the photoelectric conversion module, the transmission speed can be improved while the electronic device is made smaller. [Effects of the Invention]

[0026] The optoelectronic hybrid board of the present invention allows for greater freedom in designing the conductor layers without multi-layering the electric circuit board, thereby enabling a thinner board while suppressing optical transmission loss and improving transmission speed. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a cross-sectional view (cross-sectional view taken along line XX in FIG. 2A) along the longitudinal direction of an embodiment of a photoelectric conversion module in which a first element and a second element are mounted on a photoelectric hybrid substrate. [Figure 2]Fig. 2A is a plan view of one embodiment of a photovoltaic conversion module as viewed from one side in the thickness direction, and Fig. 2B is a plan view of a metal supporting board provided in the photovoltaic conversion module of Fig. 2A as viewed from the other side. [Figure 3] 3 is a cross-sectional view (YY cross-sectional view in FIG. 2A) along the width direction of the photoelectric hybrid substrate provided in the photoelectric conversion module shown in FIG. 2A. [Figure 4] FIG. 4 is a plan view showing a first modified example of the island portion. [Figure 5] FIG. 5 is a plan view showing a second modified example of the island portion. [Figure 6] FIG. 6 is a plan view showing a third modified example of the island portion. [Figure 7] FIG. 7 is a plan view showing a fourth modified example of the island portion. [Figure 8] FIG. 8 is a plan view showing a fifth modified example of the island portion. [Figure 9] FIG. 9 is a plan view showing a sixth modified example of the island portion. [Figure 10] FIG. 10 is a cross-sectional view along the longitudinal direction of another embodiment of a photovoltaic conversion module. DETAILED DESCRIPTION OF THE INVENTION

[0028] 1. One embodiment An embodiment of an optoelectronic hybrid board will be described with reference to FIGS. 1, 2A, 2B, and 3. FIG.

[0029] (1) Optoelectronic hybrid board (1-1) Overall structure The optoelectronic hybrid board 1 includes an optical waveguide 2 and an electric circuit board 3 arranged in one direction in the thickness direction. The optoelectronic hybrid board 1 has a flat plate shape extending from one side to the other in the longitudinal direction perpendicular to the thickness direction. Each of these components will be described in detail below.

[0030] (1-2) Optical waveguide The optical waveguide 2 is the other side portion in the thickness direction of the optoelectronic hybrid substrate 1. The optical waveguide 2 is provided throughout the entire optoelectronic hybrid substrate 1, from one side to the other in the longitudinal direction of the optoelectronic hybrid substrate 1. The optical waveguide 2 includes an overclad 23, a core 22, and an underclad 21, which are arranged in this order toward one side in the thickness direction of the optoelectronic hybrid substrate 1.

[0031] The underclad 21 is disposed on the other surface in the thickness direction of the metal supporting board 4 (described later) of the electric circuit board 3. The underclad 21 has the same shape as the outer shape of the optical waveguide 2 in plan view.

[0032] The core 22 is disposed on the other surface in the thickness direction of the underclad 21. The core 22 is also disposed at the center of the underclad 21 in the width direction (direction perpendicular to both the thickness direction and the longitudinal direction).

[0033] One longitudinal end of the core 22 is located on the other side of the longitudinal direction from an island portion 41, which will be described later. More specifically, the one longitudinal end of the core 22 is located between a first terminal 61 and a second terminal 62, which will be described later. Meanwhile, the other longitudinal end of the core 22 extends to the same position as the other longitudinal end of the optoelectronic hybrid substrate 1.

[0034] A mirror 24 is also formed in the core 22. The mirror 24 is disposed opposite a light receiving portion or a light emitting portion of a first element 7 (described later) in the thickness direction of the optoelectronic hybrid substrate 1. An optical signal optically transmitted through the core 22 to one side in the longitudinal direction undergoes optical path conversion by the mirror 24 and is received by the light receiving portion of the first element 7. An optical signal emitted from the light emitting portion of the first element 7 also undergoes optical path conversion by the mirror 24, enters the core 22, and is optically transmitted via the core 22 to the other side in the longitudinal direction.

[0035] The overclad 23 is disposed on the other surface in the thickness direction of the underclad 21. The overclad 23 also covers the core 22.

[0036] Examples of materials for the underclad 21, core 22, and overclad 23 include transparent resin materials such as epoxy resin, acrylic resin, and silicone resin. Epoxy resin is preferred from the viewpoint of optical signal transmission. The material for the core 22 has a higher refractive index than the materials for the underclad 21 and overclad 23. The thickness of the optical waveguide 2 is, for example, 10 μm or more and, for example, 200 μm or less.

[0037] (1-3) Electric circuit board The electric circuit board 3 is located on one side in the thickness direction of the optoelectronic hybrid board 1, and is disposed on one surface in the thickness direction of the optical waveguide 2. The electric circuit board 3 is provided over the entire optoelectronic hybrid board 1 from one side to the other in the longitudinal direction of the optoelectronic hybrid board 1. The electric circuit board 3 includes, in order toward one side in the thickness direction of the optoelectronic hybrid board 1, a metal supporting board 4, a base insulating layer 5 as an insulating layer, a conductor layer 6, and a cover insulating layer 12.

[0038] The metal supporting board 4 is disposed on one surface in the thickness direction of the optical waveguide 2. The metal supporting board 4 improves the mechanical strength of the electric circuit board 3. The metal supporting board 4 has a generally flat plate shape extending from one longitudinal direction to the other. One longitudinal end of the metal supporting board 4 extends to the same position as one longitudinal end of the optoelectronic hybrid board 1. The other longitudinal end of the metal supporting board 4 is located on the one longitudinal end side of the optical path of the optical signal whose optical path has been converted by the mirror 24 or the optical signal emitted from the light-emitting portion of the first element 7, and on the other longitudinal side of the first terminal 61 on one longitudinal side of the first terminal pair 61P (described later) so that the optical signal can pass through.

[0039] Examples of materials for the metal supporting board 4 include 42 alloy, aluminum, copper-beryllium, phosphor bronze, copper, silver, aluminum, and stainless steel. From the viewpoint of ensuring excellent mechanical strength and conductivity of the island portions 41 (described later), stainless steel is preferred. The thickness of the metal supporting board 4 is, for example, 3 μm or more, or preferably 10 μm or more, and for example, 100 μm or less, or preferably 50 μm or less.

[0040] The insulating base layer 5 is disposed on one surface in the thickness direction of the metal supporting board 4. The insulating base layer 5 is provided over the entire optoelectronic hybrid substrate 1 from one side to the other in the longitudinal direction of the optoelectronic hybrid substrate 1. Examples of materials for the insulating base layer 5 include polyimide. The thickness of the insulating base layer 5 is, for example, 2 μm or more and, for example, 50 μm or less.

[0041] The insulating base layer 5 has a first through hole 31 and a second through hole 32 penetrating the insulating base layer 5 in the thickness direction at a position overlapping the island portion 41 in the thickness direction. The first through hole 31 and the second through hole 32 are arranged at an interval from each other in the width direction. The first through hole 31 overlaps one widthwise end of the island portion 41 in the thickness direction. The second through hole 32 overlaps the other widthwise end of the island portion 41 in the thickness direction.

[0042] The conductor layer 6 is disposed on one surface in the thickness direction of the insulating base layer 5. Examples of materials for the conductor layer 6 include conductors such as copper. The thickness of the conductor layer 6 is, for example, 2 μm or more and, for example, 20 μm or less.

[0043] The conductor layer 6 includes a plurality of terminals 80 and a plurality of wirings 90 that connect the plurality of terminals 80 together.

[0044] The multiple terminals 80 include a first terminal 61, a second terminal 62, and a third terminal 63. The first terminal 61, the second terminal 62, and the third terminal 63 are spaced apart from one another and arranged in this order toward one side in the longitudinal direction of the electric circuit board 3. In the longitudinal direction, the distance between the second terminal 62 and the third terminal 63 is longer than the distance between the first terminal 61 and the second terminal 62. This makes use of the space between the second terminal 62 and the third terminal 63 to form the island portion 41.

[0045] 2A , a plurality of first terminals 61 are arranged so as to be included in the first element 7 in a plan view in order to electrically connect to the electrodes 71 of the first element 7. More specifically, the plurality of first terminals 61 are arranged side by side in the width direction, with a pair of first terminals 61 adjacent to each other in the longitudinal direction being defined as a first terminal pair 61P. The first terminal pair 61P is arranged so that an optical signal whose optical path has been changed by the mirror 24 or an optical signal emitted from the light-emitting portion of the first element 7 can pass between the first terminal pair 61P.

[0046] The second terminal 62 is arranged on one side in the longitudinal direction relative to the first terminal 61. The second terminals 62 are arranged so as to be included in the second element 8 in a plan view in order to be electrically connected to the electrodes 81 of the second element 8. In detail, the second terminals 62 are arranged such that a pair of second terminals 62 adjacent to each other in the longitudinal direction constitutes a second terminal pair 62P, and the second terminal pairs 62P are arranged side by side in the width direction.

[0047] The third terminal 63 is arranged on one side in the longitudinal direction relative to the second terminal 62. The third terminal 63 is arranged on the opposite side of the first terminal 61 relative to the second terminal 62 in the longitudinal direction. A plurality of third terminals 63 are arranged so as to be included in the external substrate 10 in a plan view in order to be electrically connected to the electrodes 11 of the external substrate 10. More specifically, the plurality of third terminals 63 are arranged side by side in the width direction.

[0048] The terminal 80 is provided with a plating layer 9. Examples of materials for the plating layer 9 include gold, silver, tin, a tin alloy, and nickel.

[0049] The plurality of wirings 90 includes a first wiring 64 , a second wiring 65 , and a third wiring 66 .

[0050] The first wiring 64 is electrically connected to the second terminal 62 (specifically, the second terminal 62 on one longitudinal side of the second terminal pair 62P) and a first via 51, which will be described later. The first wiring 64 is a differential wiring, a clock wiring, or other signal wiring. The first wiring 64 is preferably a signal wiring other than a differential wiring or a clock wiring.

[0051] The second wiring 65 is electrically connected to a first via 51 (described later) and a third terminal 63. The second wiring 65 is a differential wiring, a clock wiring, or other signal wiring. The second wiring 65 is preferably a signal wiring other than a differential wiring or a clock wiring.

[0052] The third wiring 66 is electrically connected to the second terminal 62 (specifically, the second terminal 62 on one longitudinal side of the second terminal pair 62P) and the third terminal 63. The third wiring 66 is a differential wiring, a clock wiring, or other signal wiring. The third wiring 66 is preferably a differential wiring and a clock wiring. In FIG. 2A, the third wiring 66 is a differential wiring and is depicted as two wirings.

[0053] The third wiring 66 passes over the island portion 41 between a first via 51 and a second via 52, which will be described later.

[0054] The third wiring 66 includes an intermediate conductor portion 16. The intermediate conductor portion 16 is a portion of the third wiring 66 on the island portion 41 that is disposed between a first via 51 and a second via 52, which will be described later.

[0055] The wiring 90 also includes a plurality of fourth wirings 67. The fourth wirings 67 are electrically connected to the first terminals 61 (specifically, the first terminals 61 on one side in the longitudinal direction of one pair of first terminals 61P) and the second terminals 62 (specifically, the second terminals 62 on the other side in the longitudinal direction of one pair of second terminals 62P).

[0056] The cover insulating layer 12 is disposed on one surface in the thickness direction of the base insulating layer 5. The cover insulating layer 12 covers the plurality of wirings 90. Examples of materials for the cover insulating layer 12 include polyimide. The thickness of the cover insulating layer 12 is, for example, 2 μm or more and, for example, 50 μm or less.

[0057] (1-4) Island section The island portion 41 is provided on the metal supporting board 4. The island portion 41 is located between the second terminal 62 and the third terminal in the longitudinal direction of the optoelectronic hybrid substrate 1. The island portion 41 is located approximately at the center in the width direction of the optoelectronic hybrid substrate 1. The island portion 41 has a substantially rectangular shape extending in the width direction. The width of the short side of the island portion 41 is, for example, 0 to 500 μm, and preferably 60 to 250 μm. The width of the long side of the island portion 41 is, for example, 200 to 5000 μm, and preferably 300 to 3000 μm.

[0058] The island portion 41 is spaced apart from its surroundings so as to be electrically insulated from the surroundings. The distance (shortest distance) between the island portion 41 and the surrounding metal supporting board 4 is not particularly limited, but is, for example, 0 to 200 μm, and is 20 to 120 μm. Specifically, a groove 42 is formed between the island portion 41 and the surrounding metal supporting board 4. The groove 42 has a substantially rectangular frame shape extending in the width direction in bottom view so as to surround the island portion 41. The groove 42 penetrates the metal supporting board 4 in the thickness direction. The groove 42 is filled with the same resin as the material of the underclad 21. The island portion 41 is made of the same material as the metal supporting board 4 and is conductive.

[0059] The conductor layer 6 includes a first via 51 and a second via 52 that are filled in the first through hole 31 and the second through hole 32, respectively, provided in the base insulating layer 5. The first via 51 and the second via 52 are arranged at an interval from each other in the width direction. The first via 51 overlaps one widthwise end of the island portion 41 in the thickness direction. The second via 52 overlaps the other widthwise end of the island portion 41 in the thickness direction. The first via 51 electrically connects the first wiring 64 and the island portion 41. The second via 52 electrically connects the second wiring 65 and the island portion 41.

[0060] (1-5) Photoelectric conversion module The photoelectric conversion module 100 comprises the above-mentioned photoelectric hybrid substrate 1, a first element 7 electrically connected to a plurality of first terminals 61, a second element 8 electrically connected to a plurality of second terminals 62, and an external substrate 10 electrically connected to a plurality of third terminals 63.

[0061] The first element 7 is at least one of a light receiving element and a light emitting element. The light receiving element has a light receiving section (not shown) and converts an optical signal received by the light receiving section from the optical waveguide 2 via the mirror 24 into an electrical signal. An example of the light receiving element is a photodiode (PD). The light emitting element has a light emitting section (not shown) and converts an electrical signal into an optical signal, which is emitted from the light emitting section and transmitted to the optical waveguide 2 via the mirror 24. An example of the light emitting element is a vertical cavity surface emitting laser (VCSEL). The first element 7 is mounted on the optoelectronic hybrid substrate 1 by electrically connecting the electrode 71 to the first terminal 61.

[0062] The second element 8 is at least one of a driving element and an amplifying element. The driving element receives a power supply current (power) and drives the light-emitting element. An example of the driving element is a driving IC (DRIVER). The amplifying element amplifies the electrical signal transmitted from the light-receiving element. An example of the amplifying element is a transimpedance amplifier (TIA). The second element 8 is mounted on the optoelectronic hybrid board by electrically connecting the electrode 81 to the second terminal 62.

[0063] The external substrate 10 is a component separate from the optoelectronic hybrid substrate 1 and the optoelectronic conversion module 100. An example of the external substrate 10 is a printed circuit board. The external substrate 10 is connected to the optoelectronic hybrid substrate 1 by electrically connecting the electrode 11 to the third terminal 63. For example, the electrode 11 is connected to the third terminal 63 via a joining member 15 (solder).

[0064] When the first element 7 is a light receiving element, an amplifying element is mounted on the second element 8. In this case, the photoelectric conversion module 100 converts an optical signal into an electrical signal. When the first element 7 is a light emitting element, a driving element is mounted on the second element 8. In this case, the photoelectric conversion module 100 converts an electrical signal into an optical signal.

[0065] When the first element 7 is a light receiving element, an optical signal transmitted from the optical transmission path 14 indicated by a dashed line enters the other longitudinal end of the core 22 of the optical waveguide 2 of the optoelectric conversion module 100 via the optical connector 13 indicated by a dashed line. The optical signal then passes through the core 22 of the optical waveguide 2 and is transmitted to one longitudinal side, reaching the mirror 24. The optical path of the optical signal is then converted perpendicularly to one thickness side at the mirror 24, and the optical signal enters the light receiving portion of the light receiving element disposed on one thickness side of the mirror 24. The optical signal is converted into an electrical signal at the light receiving element. The electrical signal is then transmitted to the amplifier element via the fourth wiring 67. The electrical signal from the amplifier element is transmitted to the external substrate 10 via multiple wirings 90 (including the first wiring 64, the second wiring 65, and the third wiring 66).

[0066] When the first element 7 is a light-emitting element, first, an electrical signal transmitted from the external substrate 10 is transmitted to the driving element via a plurality of wirings 90 (including the first wiring 64, the second wiring 65, and the third wiring 66). The electrical signal is then transmitted from the driving element to the light-emitting element via a fourth wiring. In the light-emitting element, the electrical signal is converted into an optical signal. Then, the optical signal is emitted perpendicularly from the light-emitting portion of the optical element to the other side in the thickness direction and reaches the mirror 24. In the mirror 24, the optical signal is optically path-converted to the other side in the longitudinal direction and is incident on one side in the longitudinal direction of the core 22 of the optical waveguide 2. Then, the optical signal is transmitted through the core 22 to the other end in the longitudinal direction of the core 22 and transmitted to the optical transmission line 14 via the optical connector 13.

[0067] (1-6) Manufacturing method of photoelectric hybrid board and photoelectric conversion module The following describes an example of a method for manufacturing the above-mentioned optoelectronic hybrid substrate 1 and optoelectronic conversion module 100. To prepare the optoelectronic hybrid substrate 1, first, an electric circuit board 3 is prepared, and then the optical waveguide 2 is formed on the electric circuit board 3.

[0068] To prepare the electric circuit board 3, first, a metal supporting board 4 made of a metal sheet is prepared, and then an insulating base layer 5, a conductor layer 6, and an insulating cover layer 12 are formed in this order on one side in the thickness direction of the metal supporting board 4.

[0069] In manufacturing the above-described electric circuit board 3, when the insulating base layer 5 is formed, the first through hole 31 and the second through hole 32 are formed in the insulating base layer 5 by photolithography. Furthermore, when the conductor layer 6 is formed, the first via 51 and the second via 52 are formed in the first through hole 31 and the second through hole 32 by plating. Furthermore, when the metal sheet is shaped by etching to form the metal supporting board 4, grooves 42 are formed, and island portions 41 surrounded by the grooves 42 are formed. In this manner, the electric circuit board 3 is prepared.

[0070] Next, the optical waveguide 2 is formed on the electric circuit board 3. For example, by applying a photosensitive resin composition containing the above-mentioned transparent resin material and by photolithography, the underclad 21, core 22, and overclad 23 are formed in this order on the other side in the thickness direction of the electric circuit board 3. At this time, when the underclad 21 is formed, the groove 42 is filled with resin. Thereafter, a mirror 24 is formed on the optical waveguide 2 including the core 22 by laser processing or cutting processing. In this manner, the optical waveguide 2 is prepared.

[0071] In this manner, the optoelectronic hybrid substrate 1 having the island portion 41 is manufactured.

[0072] Thereafter, the first element 7 and the second element 8 are mounted on the optoelectronic hybrid substrate 1, and an external substrate 10 is connected, thereby manufacturing the optoelectronic conversion module 100. On the optoelectronic hybrid substrate 1, the first element 7 is mounted on the first terminal 61, and the second element 8 is mounted on the second terminal 62 in a conventional manner. In addition, the external substrate 10 is connected to the third terminal 63. In this manner, the optoelectronic conversion module 100 is manufactured.

[0073] (1-7) Effects of this embodiment [1] In the optoelectronic hybrid substrate 1, the first wiring 64 is electrically connected to the island portion 41 through the first via 51, and the second wiring 65 is electrically connected to the island portion 41 through the second via 52. Therefore, an electrical signal transmitted from the second terminal 62 through the first wiring 64 is transmitted to the second wiring 65 through the first via 51, the island portion 41, and the second via 52, and then transmitted from the second wiring 65 to the third terminal 63. Meanwhile, the third wiring 66 passes over the island portion 41 between the first via 51 and the second via 52 in a plan view. This allows for greater flexibility in wiring design by utilizing the space between the second terminal 62 and the third terminal 63. Moreover, the island portion 41 is provided on the metal supporting board 4. This allows for greater flexibility in wiring design without the need to multilayer the electric circuit board 3. Therefore, the optoelectronic hybrid substrate 1 can be made thinner, while suppressing optical transmission loss and improving transmission speed.

[0074] [2] In the optoelectronic hybrid substrate 1, the metal supporting board 4 has a groove 42 filled with resin between the island portion 41 and the surrounding metal supporting board 4. This can improve the insulation of the island portion 41 from the surrounding metal supporting board 4. Furthermore, filling the groove 42 with resin can improve the adhesion of the island portion 41 to the underclad 21 and the electric circuit board 3.

[0075] [3] In the optoelectronic hybrid substrate 1, the resin filled in the grooves 42 is the same material as the underclad 21. This allows the resin filled in the grooves 42 to be integrated with the underclad 21, further improving the adhesion of the island portion 41 to the underclad 21.

[0076] [4] In the optoelectronic hybrid board 1, one longitudinal end of the core 22 is located on the other longitudinal side of the island portion 41. In other words, the island portion 41 and the core 22 do not overlap in the thickness direction of the optoelectronic hybrid board 1. This allows the island portion 41 to be designed independently of the optical transmission of the core 22, and also prevents degradation of the optical signal due to the island portion 41.

[0077] [5] In the optoelectronic hybrid board 1, the third wiring 66 includes at least one of a differential wiring and a clock wiring, and the first wiring 64 and the second wiring 65 include signal wiring other than the differential wiring and the clock wiring. By using the differential wiring or clock wiring that requires high-precision transmission as the third wiring 66, high-precision transmission can be ensured. At the same time, by using the other wiring as the first wiring 64 and the second wiring 65 that pass through the island portion 41, the degree of freedom in wiring design can be increased.

[0078] [6] The optoelectronic conversion module 100 includes an optoelectronic hybrid substrate 1, a first element 7, a second element 8, and an external substrate 10. Because the optoelectronic conversion module 100 includes the optoelectronic hybrid substrate 1, the optoelectronic conversion module 100 can be made thinner while improving transmission speed. (1-8) Variations In the following modifications, the same components as those in the above-described embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, each modification can achieve the same effects as those in the above-described embodiment unless otherwise specified. Furthermore, the embodiment and its modifications can be combined as appropriate.

[0079] In the above embodiment, the island portion 41 extends along the width direction, but is not limited to this.

[0080] 4, in the first modification, the island portion 41 extends in a direction inclined from the width direction. Specifically, the island portion 41 extends in a direction intersecting the width direction and the longitudinal direction. The groove 42 surrounding the island portion 41 also extends in the same direction.

[0081] In the above embodiment, the island portion 41 has a substantially rectangular shape extending in the width direction, but is not limited to this.

[0082] 5, in the second modification, the island portion 41 has an L-shape. The groove 42 surrounding the island portion 41 also has an L-shaped frame shape. The first wiring 64 extends in the longitudinal direction, while the second wiring 65 extends in the width direction.

[0083] In the above embodiment, an electrical signal is transmitted from one first wiring 64 to one second wiring 65 via the island portion 41, but the present invention is not limited to this.

[0084] 6, in the third modification, the conductor layer 6 includes two second vias 52a, 52b and two second wirings 65a, 65b. The two second vias 52a, 52b are arranged at a distance from each other on the other widthwise side of the first via 51 so as to overlap with the island portion 41 in the thickness direction. Each of the two second vias 52a, 52b is electrically connected to each of the two second wirings 65a, 65b. The two second wirings 65a, 65b extend parallel to each other in the longitudinal direction.

[0085] As a result, an electrical signal transmitted from the first wiring 64 reaches the island portion 41 through the first via 51, and is then transmitted to the two second wirings 65a, 65b through the two second vias 52a, 52b. That is, in the third modification, an electrical signal is transmitted from the single first wiring 64 through the island portion 41 to the two second wirings 65a, 65b.

[0086] In the above embodiment, there is one island portion, but the present invention is not limited to this.

[0087] As shown in FIG. 7 , in the fourth modification, the metal supporting board 4 includes two island portions 41a and 41b. The conductor layer 6 includes two first vias 51a and 51b, two second vias 52a and 52b, two first wirings 64a and 64b, and two second wirings 65a and 65b corresponding to the two island portions 41. Each of the two island portions 41a and 41b has a substantially rectangular shape extending along the width direction. The two island portions 41a and 41b are disposed with a gap between them in the longitudinal direction. Grooves 42a and 42b, each having a substantially rectangular frame shape extending along the width direction, are formed around each of the two island portions 41a and 41b, respectively. The two grooves 42a and 42b are connected in the longitudinal direction to form a single groove. The first via 51a and the second via 52a are spaced apart from each other and overlap with the island portion 41a in the thickness direction. The first via 51b and the second via 52b are spaced apart from each other and overlap with the island portion 41b in the thickness direction. The two first wirings 64a, 64b extend parallel to each other in the longitudinal direction, while the two second wirings 65a, 65b extend parallel to each other in the width direction.

[0088] The first wiring 64a, the first via 51a, the island portion 41a, the second via 52a, and the second wiring 65a are electrically connected. The first wiring 64b, the first via 51b, the island portion 41b, the second via 52b, and the second wiring 65b are electrically connected. The transmission path of the electrical signal passing through the island portion 41a and the transmission path of the electrical signal passing through the island portion 41b are independent of each other.

[0089] Specifically, an electrical signal transmitted from the first wiring 64a reaches the island portion 41a through the first via 51a and is then transmitted to the second wiring 65a through the second via 52a. An electrical signal transmitted from the first wiring 64b reaches the island portion 41b through the first via 51b and is then transmitted to the second wiring 65b through the second via 52b. That is, in the fourth modification, electrical signals are transmitted independently from the two first wirings 64a and 64b to the two second wirings 65a and 65b through the two island portions 41a and 41b.

[0090] In the above embodiment, the third wiring 66 is disposed between the first via 51 and the second via 52, but the present invention is not limited to this.

[0091] As shown in FIG. 8 , in the fifth modification, instead of the two third wirings 66, the conductor layer 6 includes a functional conductor layer 68 extending in the longitudinal direction. The functional conductor layer 68 is arranged to include the second wiring 65 in a planar view. One widthwise end of the functional conductor layer 68 includes the island portion 41 between the first via 51 and the second via 52 in a planar view. The portion of the functional conductor layer 68 between the first via 51 and the second via 52 is the intermediate conductor portion 16. In other words, the functional conductor layer 68 includes the intermediate conductor portion 16. The functional conductor layer 68 also includes an opening 92 surrounding the second wiring 65. A gap is provided between the functional conductor layer 68 around the opening 92 and the second wiring 65. This provides insulation between the functional conductor layer 68 and the second wiring 65. The functional conductor layer 68 may be, for example, a magnetic shield layer or a ground layer. The first wiring extends along the longitudinal direction, while the second wiring extends along the width direction.

[0092] As shown in FIG. 9 , in the sixth modification, instead of the two third wirings 66, the conductor layer 6 includes two intermediate terminals 91 as intermediate conductor portions 16. The island portion 41 has a crank shape extending from one side to the other side in the width direction. The island portion 41 includes a main body portion 41x along the longitudinal direction, a one portion 41y extending from the other longitudinal end of the main body portion 41x to one end in the width direction, and a other portion 41z extending from the one longitudinal end of the main body portion 41x to the other side in the width direction. A crank-shaped groove 42 is formed around the island portion 41. A first via 51 overlaps one end of the one portion 41y in the thickness direction. A second via 52 overlaps the other end of the other portion 41z in the thickness direction. Third vias 53 overlap one longitudinal end and the other longitudinal end of the main body portion 41x in the thickness direction. Two intermediate terminals 91 are provided so as to overlap the two third vias 53. As a result, the island portion 41 is electrically connected to the two intermediate terminals 91 through the two third vias 53. The first wiring 64 and the second wiring 65 extend along the longitudinal direction. The sixth modified example also includes a functional conductor layer 68. The functional conductor layer 68 extends along the longitudinal direction and is arranged to include the two intermediate terminals 91 in a plan view. The functional conductor layer 68 has an opening 92 that surrounds the intermediate terminal 91. A gap is provided between the functional conductor layer 68 around the opening 92 and the intermediate terminal 91. As a result, the functional conductor layer 68 and the intermediate terminal 91 are insulated from each other.

[0093] In the above embodiment, the grooves 42 provided in the metal supporting board 4 are filled with the same resin as the material of the underclad 21, but the present invention is not limited to this.

[0094] In the seventh modification, although not shown, the grooves 42 provided in the metal supporting board 4 are filled with a resin that is the same as the material of the insulating layers (the base insulating layer 5 and the cover insulating layer 12). In the seventh modification, the resin is the same as the material of the insulating layers, so that the insulation properties of the island portion 41 can be further improved.

[0095] In the above embodiment, the photoelectric conversion module 100 is connected to the optical transmission line 14 via the optical connector 13, but the present invention is not limited to this.

[0096] As shown in Fig. 10, in the eighth modification, two photoelectric conversion modules 100a and 100b are connected to form an in-device photoelectric conversion module 101. The in-device photoelectric conversion module 101 is used in a data center, a single device, or the like. In this case, in Fig. 10, if the first element 7 on one side in the longitudinal direction is a light-emitting element 7a, the second element 8 is a driving element 8a, and the first element 7 on the other side in the longitudinal direction is a light-receiving element 7b, and the second element 8 is an amplifying element 8b.

[0097] In this case, an electrical signal transmitted from the external substrate 10a of the photoelectric conversion module 100a is transmitted to the driver element 8a and the light-emitting element 7a via the multiple wirings 90a of the photoelectric conversion module 100a. The light-emitting element 7a converts the electrical signal into an optical signal, and the optical signal is emitted from the light-emitting portion toward the mirror 24a. The optical signal from the mirror 24a enters the core 22a, passes through the core 22a, reaches one longitudinal end of the core 22b of the photoelectric conversion module 100b, and then passes through the core 22b to the mirror 24b. The light-receiving element 7b receives the optical signal from the mirror 24b at its optical receiving portion and converts the optical signal into an electrical signal. The electrical signal is then transmitted from the light-receiving element 7b to the amplifier element 8b and the external substrate 10b via the multiple wirings 90b. Note that in the internal photoelectric conversion module 101, the multiple wirings 90a and 90b can be directly connected to transmit electrical signals in parallel with optical signals.

[0098] As described above, in the eighth modification, an electrical signal is converted into an optical signal, transmitted, and then the optical signal is converted back into an electrical signal, thereby enabling high-speed communication within the device.

[0099] 2. Devices equipped with photoelectric conversion modules (1) Optical communication devices The optical communication device includes the above-described photoelectric conversion module 100 and an optical transmission line 14 connected to the photoelectric conversion module 100. The optical transmission line 14 is usually connected via an optical connector 13. An example of the optical transmission line 14 is an optical fiber cable. The optical communication device is connected to, for example, another optical communication device via the optical transmission line 14.

[0100] Examples of optical communication devices include active optical cables (AOCs) and optical transceivers. (2)Electronic equipment An electronic device includes the above-described photoelectric conversion module 100. Such an electronic device can transmit and receive optical signals at high speed within the device or between other electronic devices. The electronic device is suitable for use in data centers and other places where high-speed communication is required.

[0101] Examples of electronic devices include servers and switches in data centers. [Explanation of symbols]

[0102] 1 Optoelectronic mixed board 2 Optical waveguide 3 Electrical circuit board 4 Metal Support Board 5 Base insulation layer 6 Conductor Layer 7 First element 8 Second element 10 External board 11, 71, 81 electrodes 12 Cover insulation layer 13 Optical Connector 14 Optical transmission line 15 Joining material (solder) 16 Intermediate conductor 21 Underclad 22 cores 23 Overclad 31 First through hole 32 Second through hole 33 Third through hole 41, 41a, 41b Island part 42, 42a, 42b groove 51, 51a, 51b First via 52, 52a, 52b Second via 61 1st terminal 62 2nd terminal 63 3rd terminal 64, 64a, 64b First wiring 65, 65a, 65b Second wiring 66 3rd wiring 80 Multiple Terminals 90 Multiple Wires 100, 100a, 100b, Photoelectric conversion module

Claims

1. An optoelectronic hybrid board including an optical waveguide and an electric circuit board in one direction in a thickness direction, the optical waveguide includes an overclad, a core, and an underclad, arranged in that order in one thickness direction; the electric circuit board includes a metal supporting board, an insulating layer, and a conductor layer in this order in one thickness direction; the conductor layer includes a plurality of first terminals for electrically connecting to light receiving elements or light emitting elements, a plurality of second terminals for electrically connecting to driving elements or amplifying elements, a plurality of third terminals for electrically connecting to an external substrate, and a plurality of wirings for electrically connecting the second terminals and the third terminals; the first terminal, the second terminal, and the third terminal are spaced apart from one another and arranged in this order toward one side in the longitudinal direction of the electric circuit board, the metal supporting board includes an island portion disposed between the second terminal and the third terminal in the longitudinal direction, the island portion being spaced apart from a periphery of the island portion so as to be electrically insulated from the periphery; the insulating layer includes a first through hole and a second through hole that are spaced apart from each other and penetrate the insulating layer in the thickness direction at a position that overlaps the island portion in the thickness direction, the conductor layer further includes a first via filled in the first through hole, a second via filled in the second through hole, and an intermediate conductor portion; the plurality of wirings include a first wiring electrically connected to the first via and a second wiring electrically connected to the second via; The intermediate conductor portion is disposed between the first via and the second via.

2. the metal supporting board has a groove between the island portion and the periphery; The optoelectronic hybrid board according to claim 1 , wherein the groove is filled with a resin.

3. The optoelectronic hybrid board according to claim 2 , wherein the resin is the same material as the underclad.

4. The optoelectronic hybrid board according to claim 2 , wherein the resin is the same material as the insulating layer.

5. The optoelectronic hybrid board according to claim 1 , wherein one end of the core in the longitudinal direction is located on the other side of the island portion in the longitudinal direction.

6. the conductor layer includes a third wiring including the intermediate conductor portion, the third wiring includes at least one of a differential wiring and a clock wiring, The optoelectronic hybrid board according to claim 1 , wherein the first wiring and the second wiring include signal wiring other than differential wiring and clock wiring.

7. The photoelectric hybrid substrate according to any one of claims 1 to 6, at least one of a light receiving element and a light emitting element electrically connected to the plurality of first terminals; at least one of a driving element and an amplifying element electrically connected to the plurality of second terminals; an external substrate electrically connected to the plurality of third terminals; A photoelectric conversion module comprising:

8. The photoelectric conversion module according to claim 7 ; an optical transmission line connected to the photoelectric conversion module; An optical communication device comprising:

9. An electronic device comprising the photoelectric conversion module according to claim 7 .

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