JP5078442B2 - OPTICAL TRANSMISSION BOARD, MANUFACTURING METHOD THEREOF, OPTICAL ELECTRONIC HYBRID SUBSTRATE, AND OPTICAL MODULE - Google Patents

Description

  The present invention relates to an optical transmission board used for optical interconnection and the like and a method for manufacturing the same, and more particularly to an optical transmission board having good and uniform transmission characteristics provided in a through hole of the board. The present invention also relates to an optical module using the optical transmission board.

  In order to increase the amount of processing in information processing and improve the processing speed, the operating speed of the semiconductor device and the number of input / output terminals for electrical signals tend to increase in the future. At the same time, the number of signal wirings on the circuit board on which the semiconductor device is mounted has increased remarkably, and the electrical wiring density tends to increase. Accordingly, signal attenuation in the electrical wiring formed on the mounting substrate and crosstalk between adjacent wirings are remarkably increased, which is a serious problem. In particular, in a large-scale semiconductor integrated circuit typified by a microprocessor, it is a big problem to stably input and output signals at a GHz level with low power consumption.

  In order to solve the problem, an optical transmission technology that converts an electrical signal input / output to / from a semiconductor device into signal light and transmits light corresponding to the signal light through an optical wiring such as an optical waveguide formed on a mounting substrate. Is being considered.

  In the photoelectric conversion unit that converts the signal light and the electrical signal, a light-emitting optical semiconductor element such as a semiconductor laser (LD) or a light-emitting diode (LED) mainly composed of a compound semiconductor is received on the transmission output side. On the input side, an optical semiconductor element for receiving light such as a photodiode (PD) made of silicon (Si) or a compound semiconductor is used.

  By the way, there are various types of semiconductor lasers. In recent years, since a good crystal can be obtained on the crystal growth surface, a surface emitting laser in which the light emitting part emits light in a direction perpendicular to the main surface of the element substrate. (VCSEL) is being widely used as a transmission light source with high performance and low cost. On the other hand, a photodiode of a surface light receiving type in which a light receiving portion is on the crystal surface is generally used.

  In a conventional optical transmission board, a clad made of a material with a low refractive index around the core part made of a material with a high refractive index as an optical wiring arranged on or in the substrate parallel to the substrate surface What provided the optical waveguide formed by covering with a part is known. Such optical waveguides are made using optical glass or single crystal or polymer optical materials.

  In addition, a conventional optical module in which optical wiring and electrical wiring are mixedly mounted is known to have an optical coupling structure of the optical semiconductor element and the optical waveguide. In such an optical module, since the input / output direction of the signal light and the optical waveguide formed on the mounting substrate are substantially perpendicular to each other, various proposals have been made to obtain a high coupling light quantity.

In Patent Document 1, a cylindrical core part and a peripheral part (cladding part) having a lower refractive index than the core part are formed inside a cylindrical through-hole penetrating between both main surfaces of the substrate. An optical module having a light propagating body is disclosed.
WO 2001/1176 pamphlet

  The light propagating body having a core part and a clad part as described in Patent Document 1 is covered with a clad part having a refractive index lower than that of the core part. Most of the light propagates through the core and is emitted.

  However, the signal light is not completely confined in the core part, and there is signal light that leaks from the core part to the cladding part and propagates through the cladding part. Since such signal light has a standing wave mode different from that of signal light propagating in the core portion, signal light that has propagated through the core portion is emitted first and then delayed. Therefore, the signal light propagating through the clad portion is emitted as noise, so that there is a tendency that the signal reliability is not sufficiently obtained.

  The present invention has been made in consideration of the above-described problems in the prior art, and an object of the present invention is to provide an optical transmission board in which the noise of a light propagating body provided in a through hole is greatly reduced, and a method for manufacturing the same. Another object is to provide an opto-electronic hybrid board and an optical module using the same.

The present invention includes a first region that penetrates between both main surfaces, the central axis is perpendicular to at least one main surface of the two main surfaces, and monotonously decreases from one main surface to the other main surface side; A substrate having a through hole connected to a second region other than the first region at a boundary portion, a clad portion provided inside the through hole in the first region, and one of the substrates An optical propagating body having a first end surface on the main surface side and a core portion having a refractive index higher than that of the cladding portion, wherein the core portion is in contact with the inner periphery of the boundary portion Regarding the substrate. Here, “monotonically decreasing” means not increasing.

  It is preferable that the light propagating body has a core portion having a refractive index higher than that of the surrounding portion in the radial direction of the through hole in the second region.

The second region of the through hole is preferably filled with the same material as the core portion .

Further, the present invention provides a substrate having a through hole penetrating between both main surfaces and having a central axis perpendicular to at least one main surface of the two main surfaces, and a clad provided inside the through hole. parts, and comprises a one principal surface side of the first end surface and the other principal surface side of the second end surface of the substrate of the substrate, comprising a core portion in which the refractive index becomes higher than the cladding portion, said through hole, the first with the end face toward the second end face diameter monotonically decreasing, the optical transmission substrate inner circumference of the second end face is provided and a light propagating body in contact with the core portion About.

  It is preferable that a metal film or a film having a lower refractive index than that of the light propagating body is further provided between the through hole and the light propagating body.

  In the end portion of the light propagating body, a concave portion recessed into the through hole from the opening periphery of the through hole is further provided, and a translucent member having a refractive index equal to or higher than the refractive index of the core portion is provided in the concave portion. Furthermore, it is preferable to have equipped.

  It is preferable to further include an optical waveguide formed on at least one main surface of the substrate and optically coupled to the light propagating body.

  According to the present invention, there is provided a single through hole having a central axis perpendicular to at least one main surface of both main surfaces, wherein the diameter is monotonously decreased from both main surfaces of the substrate toward the inside of the substrate. Step A for forming the first transparent resin having photocurability in the hole from the smallest diameter portion having the smallest diameter to one main surface among the through holes, and the other By exposing and curing the first transparent resin from the main surface side, a core portion made of the first transparent resin from the smallest diameter portion to one main surface side of the through-hole is formed. The present invention relates to a method for manufacturing an optical transmission board, comprising: a step C for forming; and a step D for forming a peripheral portion having a lower refractive index than the core portion around the core portion in the through hole.

  After the step B, after the step C and the step E, the step E of providing a recess in the end portion on the one main surface side of the first transparent resin filled in the through hole, the step It is preferable to further include a step F of filling the light-transmitting member having a refractive index equal to or higher than the refractive index of the core portion in the recess.

  One of the main surfaces of the substrate is drilled so that the diameter decreases monotonically from one main surface to the other main surface, and the central axis is perpendicular to at least one of the main surfaces. Step A ′ for forming two through-holes, Step B ′ for filling the through-holes with a first transparent resin having photocurability, and exposure of the first transparent resin from the other main surface side Step C ′ for forming a core portion made of the first transparent resin from the one main surface side to the other main surface side by curing, and in the through hole, the core portion And a step D ′ of forming a peripheral portion having a lower refractive index than that of the core portion.

After the step B ′, from the step E ′ of providing a recess at the end of at least one main surface side of the first transparent resin filled in the through hole, and from the step C ′ and the step E ′ After that, a step F ′ of filling the concave portion with a translucent member having a refractive index equal to or higher than the refractive index of the core portion;
It is preferable that it is further included.

  The present invention relates to a multilayer optical transmission substrate in which a plurality of the optical transmission substrates are stacked, the end surfaces of the light propagating bodies in each of the two adjacent optical transmission substrates are opposed to each other and optically coupled. .

  The present invention relates to an opto-electronic hybrid board comprising the optical transmission board and a conductor pattern formed on one surface of the optical transmission board.

  The present invention relates to an optical module including the opto-electronic hybrid substrate and an optical semiconductor element electrically connected to the conductor pattern on one surface of the opto-electronic hybrid substrate.

  The present invention relates to an opto-electronic hybrid substrate comprising the multilayer optical transmission substrate and a conductor pattern formed on one exposed surface of the multilayer optical transmission substrate.

  The present invention relates to an optical module comprising the multilayer optoelectronic hybrid substrate and an optical semiconductor element electrically connected to the conductor pattern on one exposed surface of the optoelectronic hybrid substrate.

  According to another aspect of the present invention, there is provided the optical transmission board according to any one of the above, a second board disposed in parallel with the optical transmission board, and a surface of the second board facing the optical transmission board. And a core part of the light propagating body in the optical transmission substrate is optically coupled to the optical waveguide.

  According to the optical transmission board of the present invention, there is provided a board having a through-hole penetrating between both main faces and having a central axis perpendicular to at least one main face of the two main faces, and the inside of the through-hole. A first region having a first end surface on one main surface side of the substrate and having a core portion having a refractive index higher than that of a peripheral portion in a radial direction of the through-hole, and the other main surface of the substrate A second region having a second end surface on the surface side, and a boundary between the first region and the second region, the first region and the second region from the first end surface and the second end surface, respectively. And a light propagating body whose diameter monotonously decreases toward the boundary portion, so that when the light is irradiated from the first region side, the peripheral portion (cladding portion) of the core portion is at the boundary portion. Because it is narrowed down greatly, the peripheral part with a lower refractive index than the core part Thereby reducing the signal light and transportable and is emitted as noise.

  In the second region, the light propagating body has a core portion whose refractive index is higher than that of the surrounding portion in the radial direction of the through hole, so that the signal light is confined and propagated in the core portion. As a result, highly efficient signal light propagation can be realized in the first region and the second region of the light propagating body.

  Since the outer periphery of the core portion is equal to the inner periphery of the through hole, the peripheral portion (cladding portion) is interrupted at the boundary portion, so that the signal is incident from the first end surface and leaks from the core portion to the peripheral portion. Light can be blocked at the boundary, and emission of the signal light can be suppressed.

According to the optical transmission board of the present invention, a board that penetrates between both main surfaces and has a through hole whose central axis is perpendicular to at least one main surface of the two main surfaces;
Provided inside the through hole, comprising a first end surface on one main surface side of the substrate and a second end surface on the other main surface side of the substrate, and having a refractive index in the radial direction of the through hole. And a light propagating body having a diameter that monotonously decreases from the first end surface toward the second end surface, so that the peripheral portion is large at the second end surface. Since it is narrowed down, the signal light that propagates to the peripheral portion (cladding portion) having a lower refractive index than the core portion and is emitted as noise can be reduced.

  Since the diameter of the core portion matches the diameter of the second end surface, only the core portion is exposed on the other main surface, so the position of the core portion is clear. Therefore, it is easy to align the core portion with an optical element such as a light receiving element or a light emitting element, another optical transmission board, an optical waveguide, and a material that can be optically coupled to the optical transmission board of the present invention. .

  By further providing a metal film or a film having a refractive index lower than that of the light propagating body between the through hole and the light propagating body, leakage of signal light to the outside of the light propagating body is suppressed. Highly efficient signal light propagation can be realized.

  In the end portion of the light propagating body, a concave portion recessed into the through hole from the opening periphery of the through hole is further provided, and a translucent member having a refractive index equal to or higher than the refractive index of the core portion is provided in the concave portion. Further, the signal light incident on the light propagating body is constrained to be diffused and condensed so as to approach the optical axis at the interface between the translucent member and the refractive index distribution body. As a result, the proportion of the signal light propagating through the core portion increases, and the signal light that propagates through the peripheral portion (cladding portion) having a lower refractive index than the core portion and is emitted as noise can be reduced.

  An optical waveguide formed on at least one main surface of the substrate and optically coupled to the light propagating body, further formed on at least one main surface of the substrate, Furthermore, it is possible to transmit the signal light in a three-dimensional manner in a good state with a small propagation loss.

  According to the method for manufacturing an optical transmission substrate of the present invention, the diameter is monotonously decreased from both main surfaces of the substrate toward the inside of the substrate, respectively, and at least one main surface of the two main surfaces Step A for forming a single through-hole having a perpendicular central axis, and a first transparent material having photocurability in the through-hole from the smallest diameter portion having the smallest diameter to one main surface. Step B of filling the resin, and exposing and curing the first transparent resin from the other main surface side, the first diameter from the smallest diameter portion of the through hole to the first main surface side. Including a step C of forming a core portion made of a transparent resin, and a step D of forming a peripheral portion having a lower refractive index than the core portion around the core portion in the through hole. Refracts more than the surrounding area without forming a mask pattern. It is possible to form a light propagating body having a high core portion. In addition, during the manufacturing process, it is also possible to suppress the inclination and collapse of the core due to the surface tension during development.

  After the step B, the step E of providing the concave portion at the end on the one main surface side of the first transparent resin filled in the through hole, and after the step C and the step E, the step And the step F of filling the light-transmitting member having a refractive index equal to or higher than the refractive index of the core portion in the recess, thereby suppressing the diffusion of the signal light incident on the light propagating body. The light is condensed so as to approach the optical axis at the interface between the member and the refractive index distributor, thereby increasing the proportion of the signal light propagating through the core portion, and the surrounding portion (cladding portion) having a lower refractive index than the core portion. It is possible to manufacture an optical transmission board in which signal light that propagates through and is emitted as noise is reduced.

  According to the method for manufacturing an optical transmission substrate of the present invention, the two main surfaces of the substrate are perforated so that the diameter monotonously decreases from one main surface to the other main surface, and at least the two main surfaces are Step A ′ for forming one through-hole having a central axis perpendicular to one main surface, Step B ′ for filling the through-hole with a first transparent resin having photocurability, and the other A step of forming a core portion made of the first transparent resin from the one main surface side to the other main surface side by exposing and curing the first transparent resin from the main surface side C ′ and the step D ′ of forming a peripheral portion having a lower refractive index than the core portion around the core portion in the through-hole, without forming a mask pattern, It is possible to form a light propagator that has a core part with a higher refractive index than the surrounding part. .

  According to the multilayer optical transmission board of the present invention, a plurality of the optical transmission boards are laminated, and the end surfaces of the light propagating bodies in each of the two adjacent optical transmission boards face each other and are optically coupled. As a result, signal light with low propagation loss can be transmitted between multiple layers.

  According to the optical module of the present invention, an opto-electronic hybrid board comprising an optical transmission board and a conductor pattern formed on one side of the optical transmission board, and the conductor on one side of the opto-electronic hybrid board By including the optical semiconductor element electrically connected to the pattern, signal light with low propagation loss can be transmitted.

  According to the composite optical transmission board of the present invention, the optical transmission board according to any one of the above, a second board arranged in parallel with the optical transmission board, and the optical transmission board in the second board facing the optical transmission board. An optical waveguide formed on the surface of the optical transmission board, and a core portion of the light propagating body in the optical transmission board is optically coupled to the optical waveguide. The transmission loss of light propagation between the two can be reduced, and good propagation characteristics can be obtained.

[Optical Transmission Board in First Aspect]
The optical transmission board according to the first aspect of the present invention will be described below with reference to FIG. 1 is merely an example of an embodiment of the optical transmission board in the first aspect of the present invention, and is not limited to FIG.

  In FIG. 1, an optical transmission substrate 1 includes a substrate 2 and a light propagating body 3, and an optical via structure having a function of conducting light from one main surface of the substrate 2 to the other main surface is formed. Is.

  The substrate 2 is penetrated between one main surface 2A and the other main surface 2B. And it has a through-hole whose central axis is perpendicular to the main surface. Such a through-hole has a diameter that monotonously decreases from one main surface 2A and the other main surface 2B toward the inside of the substrate. In addition, the said through-hole is obtained by drilling on suitable conditions, respectively using the drill and laser which are used for the drilling process of a normal printed board.

  The substrate 2 is formed from a dielectric sheet. In addition, as a dielectric material sheet, what laminated | stacked well-known materials, such as a glass epoxy resin used for the printed circuit board for electronic industries, and ceramics, such as an alumina, is used.

  The through hole in the substrate 2 is configured by a through hole in which the first region 4 is provided (hereinafter referred to as a first through hole) and a through hole in which the second region 5 is provided (hereinafter referred to as a second through hole). Here, the shape of the opening of the through hole is substantially circular.

  The light propagating body 3 is provided inside the through hole, and includes a first region 4, a second region 5, and a boundary portion 6 thereof. Here, it is preferable that the light propagating body 3 is provided in the through hole without a gap.

  The light propagating body 3 is preferably a transparent resin in order to conduct signal light from one main surface to the other main surface. Here, specific examples of the transparent resin include acrylic resins, silane resins, imide resins, and epoxy resins.

  The first region 4 includes a core portion 12A having a refractive index higher than that of the peripheral portion in the radial direction of the through-hole, and a clad portion 13A provided concentrically around the peripheral portion of the core portion 12A. Yes. Here, the core portion refers to a portion having a refractive index higher than that of the surrounding portion in the radial direction of the through hole. By forming such a refractive index distribution, the signal light is confined in the core portion. Can be propagated along the central axis.

  Even if the core part of the light propagating body in the first aspect has a refractive index whose refractive index is lowered stepwise at the boundary between the core part and the surrounding part (stepped refractive index distribution body) The refractive index in the core portion may gradually decrease from the central axis toward the periphery (graded refractive index distribution body).

  In the case of the stepped refractive index distribution body, the signal light is reflected at the boundary of the refractive index and propagated by being confined in the high refractive index region in the center, so that the light propagating body has a uniform refractive index. Compared with this, highly efficient signal light propagation can be realized.

  Further, in the case of the gradient refractive index distribution body, the signal light is confined and propagated while meandering the central portion of the light propagating body, so that wider-band signal light propagation can be realized.

  The first region 4 has a tapered shape from the first end surface 3 </ b> A toward the boundary portion 6. In addition, the 1st area | region of this invention is not restricted to a taper shape, The diameter of a 1st area | region should just monotonously reduce toward a boundary part from a 1st end surface.

  Here, when the cross-sectional shape of the first region in the substrate main surface direction is an elliptical shape, the diameter of the first region indicates the major axis of the elliptical shape. “Monotonically decreasing” means that there is no tendency to increase. For example, in this case, between the first end surface 3A and the boundary portion 6, in the first region 4, the diameter of the first end surface 3A is uniform. There may be some parts.

  The confirmation of whether or not the diameter of the first region 4 monotonously decreases is, for example, by cutting the first region 4 along its central axis, and the length of the side corresponding to the first end surface 3A in the cut surface. This can also be confirmed by comparing the length of the side corresponding to the boundary portion 6. For example, the diameter of the first region 4 in FIG. 1 is monotonously decreasing because the cross-sectional shape of the first region 4 is a trapezoid having the first end surface 3A as a long side and the boundary base 6 as a short side. It is also confirmed from that. In addition, although demonstrated here in the 1st area | region, it is completely the same also in a 2nd area | region and a boundary part.

  The outer periphery of the core portion 12A in the first region 4 is preferably equal to the inner periphery of the through hole. Since the outer periphery of the core portion is equal to the inner periphery of the through hole in this way, the cladding portion 13A is interrupted at the boundary portion 6, so that the light is incident from the first end surface 3A and enters the cladding portion 13A from the core portion 12A. The effect of blocking the leaked signal light at the boundary 6 is obtained.

  The second region 5 includes a second end surface 3B on the other main surface side 2B of the substrate 2, and the diameter monotonously decreases from the second end surface 3B toward the boundary portion 6. When a light reflecting film such as a metal film or a film having a lower refractive index than the light propagating body is provided between the through hole and the light propagating body, the inner periphery of the core portion 12A A reflective film is included.

  The second region 5 has the same member (core portion) 12B as the core portion 12A in the first region 4.

  In FIG. 1, the boundary portion 6 indicates the interface between the first region 4 and the second region 5. Since the diameters of the first region 4 and the second region 5 monotonously decrease from the first end surface 3A and the second end surface 3B toward the boundary portion 6, respectively, the diameter at the boundary portion 6 is the light propagating body 3. Is the smallest of the cross-sectional diameters.

  The core portion 12 </ b> A in the first region 4 and the core portion 12 </ b> B in the second region are optically coupled by being connected at the boundary portion 6.

  In the optical transmission board 1 of FIG. 1, for example, when light is incident from the first end surface 3A in the first region 4, the diameter of the light is changed from the diameter 12Ad in the first end surface 3A of the core portion 12A to the second of the core portion 12B. The diameter of the end surface 3B can be increased to 12Bd. Conversely, when light is incident from the second end face 3B, the diameter can be reduced from 12Bd to 12Ad.

  The first region 4 in the light propagating body of FIG. 1 has a refractive index distribution by the core portion 12A in which the refractive index is higher than the surrounding portion in the radial direction of the through hole, and the second region 5 has a uniform refractive index. Have. Further, the diameter 12Bd is larger than the diameter 12Ad at the substrate end face. As a result, the noise of the signal light can be reduced as described above, and the diameter of the incident light and the diameter of the outgoing light can be changed.

  Next, a modified example of the optical transmission board in the first aspect of the present invention will be described with reference to FIGS. 3, 5, 11, and 14.

  The optical transmission substrate 1 shown in FIG. 3 further includes a light reflection film 14 made of a metal film or a low refractive index polymer between the light propagating body 3 and the substrate 2 in the optical transmission substrate 1 shown in FIG. It is equipped. Thereby, the diameter of incident light and reflected light can be changed, and the light confinement effect can be greatly improved.

  Examples of the reflection film of the light propagating body in the first aspect include a metal film or a film having a lower refractive index than that of the light propagating body.

  Examples of the metal film include a metal film having a high reflectance at the wavelength of signal light, for example, a metal film of gold (Au), silver (Ag), aluminum (Al), or the like at a wavelength of 600 to 1500 nm.

  The low refractive index film preferably has a refractive index smaller than that of the core portion 13B. Examples of the low refractive index film include acrylic resins, silane resins, imide resins, and epoxy resins.

  When the second region 5 has a single refractive index, the light reflecting film 4 covers the second region 5 so as to improve the light confinement effect of the second region 5 and reduce the light propagation loss. Can be greatly reduced.

  The boundary portion 6 </ b> A of the optical transmission board 1 shown in FIG. 5 is interposed between the first region 4 and the second region 5. Further, the structure of the boundary portion 6A has a cylindrical shape. By forming such a structure, even when the thickness of the substrate 2 is large, the same effect as the optical transmission substrate 1 shown in FIG. 1 is obtained.

  The second region 5A of the optical transmission board 1 shown in FIG. 11 has a core portion 12B and a clad portion 13B, which is different from the second region 5 shown in FIG. 1 having only the core portion. . The optical transmission substrate 1 shown in FIG. 11 forms a symmetrical shape with the core portion 12A and the clad portion 13A in the first region 4 based on the boundary portion 6. In FIG. 11, as described above, the core portion 12A and the clad portion 13A form symmetrical shapes.

  In FIG. 11, the first region and the second region each have a core portion (12A, 12B) and a cladding portion (13A, 13B). Thereby, the light confinement effect can be sufficiently obtained even in the second region, and the light propagation loss can be suppressed to the minimum.

  The optical transmission substrate 1 shown in FIG. 14 is provided with recesses from the first end surface 3A toward the inside of the substrate 2, and further provided with recesses from the second end surface 3B toward the inside of the substrate 2, and then the recesses. Is provided with a translucent member 15.

  As the translucent member 15, a member having a refractive index equal to or higher than the refractive index of the core portions 12A and 12B is used. Specific materials include acrylic, silane, epoxy, quartz, ceramic, imide, and the like.

  In FIG. 14, the recesses are provided on both the first end surface 3 </ b> A and the second end surface 3 </ b> B, but may be provided on only one of them.

  Since the optical transmission board 1 shown in FIG. 14 has the translucent member 15, it propagates through the peripheral portion having a lower refractive index than the core portions 12 A and 12 B, and reduces the signal light emitted as noise. In addition, the effect of sufficiently condensing the light is achieved, and the propagation loss can be further suppressed.

[Optical Transmission Board in Second Aspect]
The optical transmission board according to the second aspect of the present invention will be described below with reference to FIG. 7 is merely an example of an embodiment of the optical transmission board in the second aspect of the present invention, and is not limited to FIG.

  In FIG. 7, an optical transmission substrate 23 includes a substrate 2 and a light propagating body 23, and an optical via structure having a function of conducting light from one main surface of the substrate 2 to the other main surface is formed. Is.

  The substrate 2 includes a through hole that penetrates between one main surface 2A and the other main surface 2B, and whose central axis is perpendicular to the main surface. The through hole has a diameter that monotonously decreases from one main surface 2A to the other main surface 2B. The shape of the opening of the through hole in the substrate 2 is substantially circular.

  The light propagating body 23 is provided inside the through hole, and is provided concentrically around the core portion 32 having a refractive index higher than that of the peripheral portion in the radial direction of the through hole. The clad portion 33 is formed.

  The light propagating body 23 has a tapered shape from the first end face 23A toward the second end face 23B. In the case of FIG. 7, as described above, the taper shape is used. However, the light propagating body of the present invention is not limited to this, and the diameter of the light propagating body from the first end face 23 </ b> A toward the second end face 23 </ b> B. Should be monotonously decreasing.

  As an effect obtained by the optical transmission board in the second aspect, the peripheral portion (cladding portion) having a lower refractive index than the core portion is largely narrowed in the second end face 23B, so that the signal light emitted as noise is reduced. Can be mentioned. Further, since the end surface 23B of the light propagating body and the core portion 32 on the main surface 2B have the same diameter, for example, when an optical element or the like is optically coupled to the main surface 2B side, a portion exposed to 2B is Since it is equal to the core part, alignment is easy.

[Multilayer Optical Transmission Board of the Present Invention]
A plurality of optical transmission boards in the first and second aspects are respectively laminated, and the end surfaces of the light propagating bodies of the two adjacent optical transmission boards face each other and are optically coupled. As a result, it is possible to reduce the propagation loss of signal light even between multiple layers.

  The multilayer optical transmission board of the present invention will be described below with reference to FIGS. 9 and 10 are merely examples of the embodiment of the multilayer optical transmission board of the present invention, and are not limited to only FIG. 9 and FIG.

  FIG. 9 is a cross-sectional view of a principal part schematically showing another example of the embodiment of the optical transmission board in the first embodiment of the present invention. The optical transmission board in FIG. 9 is formed by laminating a plurality of optical transmission boards (optical transmission boards in FIG. 11) having core portions in both the first region and the second region. In the structure shown in FIG. 9, the end surfaces 3A and 3B of the light propagating bodies provided on the adjacent optical transmission substrates are opposed to each other, and the light propagating bodies are optically connected to each other. Thereby, the propagation loss of signal light between multiple layers can be reduced.

  As another embodiment, for example, as shown in FIG. 10, an optical transmission further comprising a reflective film made of a metal film or a low refractive index polymer between the light propagating body and the inner wall of the through hole. A plurality of substrates (light transmission substrates in FIG. 4) are stacked. The multilayer optical transmission substrate shown in FIG. 10 can suppress signal light that becomes noise for each layer when the optical transmission substrate has a multilayer structure, and light with sufficiently suppressed noise is emitted.

  As a preferable multilayer transmission substrate in addition to the multilayer optical transmission substrate shown in FIGS. 9 and 10, for example, an optical transmission substrate having a concave portion provided with a translucent member from the second end surface toward the inside of the substrate (FIG. 14). And a plurality of such optical transmission boards).

[The optical transmission board of the present invention having an optical waveguide]
Each of the optical transmission boards in the first and second aspects can transmit light three-dimensionally by adding an optical waveguide.

  The optical transmission board 1 shown in FIG. 16 is obtained by further forming optical waveguides 10A and 10B on both main surfaces 2A and 2B of the board 2 with respect to the optical transmission board shown in FIG. The optical waveguides 10A and 10B are provided in parallel to the surface of the substrate 2, but may not be parallel to the surface of the substrate as long as they can be optically coupled to the refractive index distribution body 2. The optical waveguide 10A includes a core portion 10A2 and a clad portion 10A1 surrounding the core portion 10A2.

  In the optical transmission substrate 1 of FIG. 16, the light propagating body 3 penetrating the substrate 2 and the optical waveguide 10A are optically coupled by an optical path changing body 11A provided at the end of the optical waveguide 10A.

  Similarly, the light propagating body 3 and the optical waveguide 10B are optically coupled by an optical path changing body 11B provided at the end of the optical waveguide 11B.

  The optical waveguide 10A includes a core portion 10A2, and an upper clad portion 10A1 and a lower clad portion 10A3 surrounding the core portion 10A2. The optical path conversion body 11A includes a base body 11A1 made of a translucent member and a reflecting surface (optical path conversion surface) 11A2 formed on the base body 11A1.

  Here, the reflective surface 11A2 is coated with a metal film having a high reflectance at the wavelength of the signal light, for example, a metal film such as gold (Au), silver (Ag), or aluminum (Al) at a wavelength of 600 nm to 1500 nm. It is obtained by.

  Since the optical transmission board 1 shown in FIG. 16 has reduced signal light emitted as noise, good optical transmission is performed between the optical waveguides 10A and 10B on the one main surface 2A and the other main surface 2B. Can do.

  FIG. 16 illustrates an example in which the optical waveguides 10A and 10B are formed. However, one of the optical waveguides 10A and 10B may be formed.

  16 uses the light propagating body 3 described in FIG. 1 as the light propagating body 3, but other light propagating bodies may be used. For example, the light propagating body 3 in FIG. 3 and the light in FIG. The propagation body 3, the light propagation body 23 of FIG. 7, the light propagation body 3 of FIG. 14, etc. are mentioned. Especially, since the propagation loss is small, the light propagation body of FIG. 14 is preferable.

  FIG. 17 is a cross-sectional view of an essential part schematically showing an example of an embodiment of a composite optoelectronic substrate using the optical transmission substrate of the present invention. The composite optical transmission board shown in FIG. 17 includes the optical transmission board 1 shown in FIG. 1 and a second board 22 arranged in parallel to the optical transmission board 1. In one embodiment, when the optical transmission board 1 is a daughter board, the second board 22 is a motherboard, and electrical wiring is provided on both boards, they are electrically connected to each other via an appropriate solder connection portion (not shown). It is connected. In FIG. 17, the optical transmission substrate 1 is provided on the second substrate 20 so that the other main surface 2 </ b> B of the substrate faces the second substrate 20. In another example, the optical transmission board 1 may be a mother board, and the second board 22 may be a daughter board. In place of the optical transmission board shown in FIG. 1, the optical transmission board shown in FIG. 3, FIG. 5, FIG. 7, FIG. 11 or FIG. Also good. As shown in FIG. 18, the optical transmission substrate 1 may be provided on the second substrate 20 so that one main surface 2 </ b> A of the substrate and the second substrate 20 face each other.

  Furthermore, an optical waveguide 40 is formed on the surface 22A of the second substrate 22 that faces the optical transmission substrate 1. The light propagating body 3 formed on the optical transmission substrate 1 and the optical waveguide 40 formed on the second substrate are optically coupled by an optical path changing body 41 provided at the end of the optical waveguide 40. Directly, the core portions 12A and 12B of the light propagating body provided on the optical transmission board 1 are optically coupled to the optical waveguide 40 via the optical path changing body 41.

  The optical waveguide 40 includes a core portion 40B, and an upper clad portion 40A and a lower clad portion 40C that surround the core portion 40B. The optical path conversion body 41 includes a reflection surface (optical path conversion surface) 41A formed on the base. The reflective surface 41A is coated with a metal film having a high reflectance at the wavelength of the signal light, for example, a metal film such as gold (Au), silver (Ag), or aluminum (Al) at a wavelength of 600 to 1500 nm. The reflection surface 41A appropriately changes the optical path between the light transmission direction of the optical waveguide 40 (direction parallel to the substrate) and the light transmission direction of the light propagating body 3 (direction slightly inclined with respect to the direction perpendicular to the substrate). Provided at an angle of A method for manufacturing the composite optical transmission substrate of FIG. 17 is, for example, as follows.

  In the first step, the optical waveguide 40 is produced on one surface 42A of the second substrate 22 (for example, a mother board). In the second step, the light propagating body 3 is produced on the substrate 2 (for example, a daughter board) of the optical transmission substrate 1. In addition, since the 1st process and the 2nd process can be performed independently, they are random. In the third step, an appropriate optical semiconductor element is mounted on the optical transmission board 1. Finally, in the fourth step, the optical transmission board 1 is mounted on the second board 22.

  17 and 18, for example, a light emitting element or a light receiving element can be provided on the core portion 12A of the first end face 3A as the optical semiconductor element.

  In FIG. 17, when the light receiving element is provided on the core portion 12 </ b> A of the first end surface 3 </ b> A, the light propagated from the optical waveguide 40 and subjected to the optical path conversion on the reflection surface of the optical path conversion body 41 In the propagation of the light, the light diameter is narrowed down from 12Bd to 12Ad. For this reason, sufficiently condensed light can be incident on the light receiving element.

  In FIG. 18, when a light emitting element is provided on the second end face 3 </ b> B, the light emitted from the light emitting element is narrowed from 12 Bd to 12 Ad in propagation in the light propagating body 3. Become. And since the diameter of light can fully be made small with respect to the reflective surface in the optical path changer 41, light can be propagated in the core part 40B of the optical waveguide 40, keeping a connection loss low.

[Method of Manufacturing Optical Transmission Board in First Aspect]
The manufacturing method of the optical transmission board in the first aspect of the present invention will be described below with reference to FIG. 2 is merely an example of an embodiment of the method for manufacturing an optical transmission board in the first aspect of the present invention, and is not limited to FIG. 2 alone.

  2A to 2F are cross-sectional views of relevant parts showing an example of an embodiment of the method for manufacturing the optical transmission board shown in FIG. 1 in the order of steps. Regarding the method for manufacturing an optical transmission board according to the first aspect of the present invention, an example of the process A corresponds to FIGS. 2A and 2B, an example of the process B corresponds to FIG. An example corresponds to FIGS. 2D and 2E, and an example of the process D corresponds to FIG. In FIG. 2, the same reference numerals as those in FIG. 1 represent the same members.

Step A is a step of forming a single through hole having a central axis perpendicular to the main surface by drilling so that the diameter monotonously decreases from both main surfaces of the substrate toward the inside of the substrate. . Here, “monotonously decreases” means that there is no tendency to increase, and that there may be a portion where the diameter of the formed through-hole is uniform.

  As shown in FIG. 2 (a), by drilling the substrate 2 from the main surface 2B of the substrate 2 toward the inside of the substrate 2, the substrate 2 has the main surface 2B of the substrate toward the inside of the substrate 2. A tapered hole 7B having a reduced diameter is formed. The hole 7B is formed under appropriate conditions using a drill or a laser used in a normal printed board drilling process or the like. A mold may also be used.

  As shown in FIG. 2B, the substrate 2 is perforated at a position opposite to the hole 7B from the main surface 2A of the substrate 2 to the inside of the substrate 2, and is directed from the main surface 2A of the substrate to the inside of the substrate 2. By forming the tapered hole 7A having a reduced diameter, the substrate 2 is formed with a hole 7A located on the concentric axis with the hole 7B. The hole 7A is formed in the same manner as the hole 7B.

  Through the steps of FIG. 2A and FIG. 2B, a through hole 7 composed of a hole 7A and a hole 7B is formed. The central axis 19 of the through hole 7 is perpendicular to the main surfaces 2A and 2B of the substrate.

  2A is performed before the drilling process shown in FIG. 2B, but in process A, the drilling process shown in FIG. 2A and FIG. In combination with the drilling step described in b), drilling may be performed simultaneously from both main surfaces of one main surface 2A and the other main surface 2B.

  Step B refers to a step of filling a first transparent resin having photocurability into the hole from the smallest diameter portion 7C having the smallest diameter to one main surface among the through holes.

  As shown in FIG. 2C, the substrate 2 is filled with a first transparent resin 8 having photocurability in the through hole 7. The first transparent resin 8 is a material for forming the core portion 12A and the core portion 12B of the light propagating body 3 in FIG. 1, and is a material that is cured by light irradiation. For example, an acrylic resin, an epoxy resin, an imide resin, a silane resin, and the like can be given. In addition, the first transparent resin 8 may be one that is cured by light irradiation and whose refractive index increases.

  In FIG. 2C, the first transparent resin 8 is filled in the through hole 7, but the process B is not limited thereto, and is opposite to the main surface side exposed in the process C. It suffices if the first transparent resin 8 is filled in the range from the main surface side to the smallest diameter portion 7C having the smallest diameter among the through holes.

  For filling the first transparent resin 8, an injection method using a syringe or a suction method using vacuum suction may be used. When filling the first transparent resin 8 into the through hole 7, the upper and lower end surfaces thereof are both upper and lower main surfaces 2 </ b> A of the substrate 2 so as not to overflow from the through hole 7 or to be insufficient. And 2B are filled so as to be substantially in the same plane.

  When the first transparent resin 8 is in a liquid state, the solvent is removed by heating (prebaking) at about 100 ° C. for several minutes.

  Step C comprises the first transparent resin from the smallest diameter portion to the one main surface side of the through hole by exposing and curing the first transparent resin from the other main surface side. The process of forming the core part to be performed.

  In FIG. 2D, the first transparent resin 8 is irradiated with light from a direction perpendicular to the main surface 2B of the substrate. By irradiating with ultraviolet light from the main surface 2B side of the substrate, the whole of the first transparent resin 8 filled in the holes 7B is irradiated with light and cured. Here, of the first transparent resin 8 cured by light irradiation, a region from the substrate main surface 2B on the light irradiation side to the minimum diameter portion 7C is defined as a cured portion 8a1.

  Since the minimum diameter portion 7C serves as a mask pattern, the first transparent resin 8 filled in the hole 7A is first irradiated with light propagated from the 7B side, and the minimum diameter portion 7C is It hardens in a cylindrical shape with the bottom. Here, in the first transparent resin 8 cured by light irradiation, a region from the substrate main surface 2A on the opposite side to the light irradiation side to the minimum diameter portion 7C is defined as a cured portion 8a2.

  On the other hand, between the minimum diameter portion 7C and the main surface 2A, the peripheral portion of the first transparent resin 8a is not irradiated with light because the minimum diameter portion 7C serves as a mask pattern. One transparent resin 8 is not cured (non-cured portion 8b).

  Step D refers to a step of forming a peripheral portion having a lower refractive index than the core portion around the core portion in the through hole.

  As shown in FIG.2 (e), after performing the process of FIG.2 (d), by developing after exposure by an ultraviolet light, the non-hardened part 8b is removed and the space | gap part 16 is formed in the removal part. The

  Then, as shown in FIG. 2 (f), the second transparent resin 9 is filled in the gap 16. After filling the second transparent resin 9, the whole substrate is heated at about 100 ° C. for several tens of minutes, and so-called post-baking is performed, whereby the first transparent resin 8a1 is transferred to the core portion 12A and the second transparent resin. The resin 9 becomes the clad portion 13. The first transparent resin 8 and the second transparent resin 9 are selected so that the clad portion 13 has a lower refractive index than the obtained core portion 12A.

  2E and 2F, the gap 16 provided by development is newly filled with a second transparent resin 9 different from the first transparent resin 8, but the process D Is not limited thereto. For example, as the first transparent resin, by using a transparent resin whose refractive index increases by light irradiation, a difference in refractive index can be obtained between the portion irradiated with light and the portion not irradiated with light. Then, the process D is also achieved by performing post-baking after irradiation without performing development.

  As described above, by using the manufacturing method shown in FIG. 2, the optical transmission substrate of FIG. 1 can be smoothly formed without performing a mask pattern forming step.

  Next, a modification of the method for manufacturing an optical transmission board in the first aspect of the present invention will be described with reference to FIGS. 4, 6, 12, 13, and 15.

  FIGS. 4A to 4G are cross-sectional views of relevant parts illustrating an example of an embodiment of the method of manufacturing the optical transmission board illustrated in FIG. 3 in the order of steps. The manufacturing method of the optical transmission substrate shown in FIG. 4 is the same as the manufacturing method of the optical transmission substrate except that the step of forming the reflective film 14 (FIG. 4C) is provided between the steps of FIG. 2B and FIG. The same process as in FIG. 2 is performed. The steps shown in FIGS. 4A to 4B are the same as the steps shown in FIGS. 2A to 2B, and the steps shown in FIGS. The steps are the same as those shown in c) to (f). In the step of FIG. 4C, the reflective film is formed by, for example, coating. Here, the coating is specifically performed by plating, vapor deposition, sputtering, coating, or the like.

  6A to 6G are cross-sectional views of relevant parts showing an example of an embodiment of the method for manufacturing the optical transmission board shown in FIG. 5 in the order of steps. The optical transmission substrate manufacturing method shown in FIG. 6 is the same as that shown in FIG. 2 except that a step of providing a cylindrical through hole (step shown in FIG. 6A) is provided before the step shown in FIG. The same process is performed. Note that the steps shown in FIGS. 6B to 6G are the same as the steps shown in FIGS. In the step shown in FIG. 6A, a cylindrical through hole 7d is formed on the substrate 2 by using a drill or a laser under appropriate conditions. According to the manufacturing method shown in FIG. 6, even if the thickness of the substrate is large, a cylindrical through hole having a constant diameter is first drilled, and then the method for manufacturing the optical transmission substrate of the present invention is performed. Thus, it is possible to produce a light propagating body having excellent performance without depending on the thickness of the substrate.

  12A to 12F are cross-sectional views of relevant parts illustrating an example of an embodiment of the method for manufacturing the optical transmission board illustrated in FIG. 11 in the order of processes. In the method for manufacturing the optical transmission board shown in FIG. 12, the steps shown in FIGS. 12A to 12C are the same as the steps shown in FIGS. Moreover, the process shown to FIG.12 (e)-(f) is the same as the process shown to FIG.2 (e)-(f), respectively. In FIG. 12D, the first transparent resin 8 is exposed to ultraviolet rays using the photomask 30. As the photomask 30, for example, a photomask 30 in which a circular light-shielding portion 30 a having a diameter smaller than the through hole 7 is formed as a mask pattern can be used. In addition, 30b is a translucent part. The light shielding portion 30a is formed as a mask pattern corresponding to the central portion of the completed refractive index distribution body. And by performing exposure, light is irradiated to the translucent part 30b, and the cylindrical core part which makes the translucent part 30b a bottom face is formed.

  13 (a) to (i) are cross-sectional views of relevant parts showing an example of an embodiment of the manufacturing method of the optical transmission board shown in FIG. 11 in the order of steps, and are different from the manufacturing method shown in FIG. . The step shown in FIG. 13C shows a step of filling only the hole 7 A of the through-hole 7 with the first transparent resin 8. Note that the steps shown in FIGS. 13D and 13E are the same as the steps shown in FIGS. 2D and 2E, respectively. The step shown in FIG. 13F shows a step of filling the hole 7B with the first transparent resin 8. The step shown in FIG. 13G shows a step of irradiating ultraviolet light from the main surface 2A of the substrate. Thereby, the ultraviolet light enters the hole through the minimum diameter portion 7C of the first region and the second region. The minimum diameter portion 10C3 serves as a mask pattern and exposes the first transparent resin 12A1 inside the minimum diameter portion 7C with ultraviolet light.

  As described above, the optical transmission substrate shown in FIG. 11 can be manufactured by performing the steps shown in FIG. 12 or FIG. 12E and 13H, the minimum diameter portion 7C serves as a base for the cured portion 8a of the first transparent resin 8. Specifically, the collapse of the cured portion 8a caused by the surface tension during development can be suppressed by the minimum diameter portion 7C.

  FIGS. 15A to 15H are main-part sectional views for each process schematically showing an example of the embodiment of the method for manufacturing the optical transmission board shown in FIG. The steps shown in FIGS. 15A to 15C are the same as the steps shown in FIGS. In FIG. 15D, by using a translucent member, heating at about 100 for several minutes, and performing so-called pre-baking, a recess 34 is provided at the end of the photocurable resin filled in the through hole. (Step E). This step corresponds to step D in the method for manufacturing an optical transmission board according to the first aspect of the present invention, and is performed between step B and step C. FIGS. 15E to 15G are performed in the same manner as FIGS. 2D to 2F. In FIG. 15 (h), the light transmitting substrate of FIG. 13 is formed by filling the light transmitting member 15 in the recess 34 and performing post-baking (step F).

[Method for Manufacturing Optical Transmission Board in Second Aspect]
A method for manufacturing an optical transmission board according to the second aspect of the present invention will be described below with reference to FIG. FIG. 8 is merely an example of an embodiment of a method for manufacturing an optical transmission board in the first aspect of the present invention, and is not limited to FIG. 8 alone.

  FIGS. 8A to 8E are cross-sectional views of relevant parts showing an example of an embodiment of the method for manufacturing the optical transmission board shown in FIG. 7 in the order of steps. In the method for manufacturing an optical transmission board according to the second aspect of the present invention, an example of the process A ′ corresponds to FIG. 8A, an example of the process B corresponds to FIG. 8C corresponds to FIGS. 8C and 8D, and an example of the process D corresponds to FIG. In addition, the same code | symbol as the code | symbol of FIG. 7 represents the same member.

  Here, FIG. 8 (b) is the same process as FIG. 2 (c), FIG. 8 (d) is the same process as FIG. 2 (e), and FIG. 8 (e) is the same process as FIG. These descriptions are omitted, and only FIG. 8 (a) and FIG. 8 (c) will be described.

  As shown in FIG. 8 (a), by drilling the substrate 2 from the main surface 2A of the substrate 2 toward the main surface 2B of the substrate 2, the substrate 2 can be moved from the main surface 23B of the substrate to the inside of the substrate 2. A tapered through-hole 7 having a reduced diameter is formed.

  Further, as shown in FIG. 8C, the transparent resin 8 is cured by light irradiation from the main surface 2B of the substrate to form a columnar cured portion 8a having the minimum diameter portion 7C as the bottom surface.

  The optical transmission substrate shown in FIG. 7 can be manufactured by performing FIGS.

[Opto-electronic mixed substrate and optical module]
The opto-electronic hybrid board of the present invention comprises an optical transmission board and a conductor pattern. The optical module of the present invention comprises the opto-electronic hybrid substrate and an optical semiconductor element.

  Although the said optical module is demonstrated based on FIG. 19 and FIG. 20, the optoelectronic hybrid board and optical module of this invention are not limited to these.

  FIG. 19 is a schematic cross-sectional view of an essential part showing an example of an embodiment of the optical module of the present invention. An optical module 20 of the present invention shown in FIG. 19 has a two-layer substrate configuration in which the optical transmission substrate of FIG. In FIG. 19, the opto-electronic hybrid substrate refers to a portion excluding the optical semiconductor element 18. As an optical transmission board used for an optical module, the optical transmission board of the 1st mode and the 2nd mode is mentioned.

  First conductor patterns 17 a and 17 b are formed on the surface of the optical module 20 on the side of the optical transmission board 1, and a second conductor pattern 17 c is formed below the surface of the optical module 20. Further, a through conductor 17d that penetrates the optical module 20 and connects the first conductor pattern 17b and the second conductor pattern 17c is formed. Further, an optical semiconductor element 18 that is electrically connected to the first conductor patterns 17a and 17b is provided on the surface on the optical transmission substrate 1 side, and an optical waveguide is provided between the optical waveguide substrate 2 and the second substrate 2A. The waveguide 10C is formed. The core portion 12 </ b> A on the optical transmission board 1 side in the optical module 20 is optically coupled to the optical semiconductor element 18. Further, the optical waveguide 10C of the optical transmission board 1 and the light propagating body 3 are optically coupled by an optical path changing body 11C2.

  FIG. 20 is a schematic cross-sectional view of an essential part showing another example of the embodiment of the optical module of the present invention. In the optical module 20 of the present invention shown in FIG. 20, the first conductor patterns 17a and 17b are formed on one surface, and the second conductor pattern 17c is formed on the other surface. Furthermore, a through conductor 17d that penetrates the optical transmission board 1 and connects the first conductor pattern 17b and the second conductor pattern 17c is formed. Furthermore, an optical semiconductor element 18 that is electrically connected to the first conductor patterns 17a and 17b is provided on one surface of the optical transmission board 1. The core portion 12 A of the refractive index distribution body on one surface of the optical transmission substrate 1 is optically coupled to the optical semiconductor element 18. Further, the optical waveguide 10C of the optical transmission board 1 and the light propagating body 3 are optically coupled by an optical path changing body 11C2.

  In the optical module of the present invention, specific examples of the optical semiconductor element include a semiconductor laser, a light emitting diode, etc., which are light emitting devices, or a photodiode, etc., which is a light receiving device. The optical semiconductor element 18 is mounted on the first conductor pattern formed on the optical transmission substrate 1 with the light emitting point (not shown) as an active region facing the optical transmission substrate 1, and the electrode thereof is the first conductor pattern. It is joined to the conductor pattern. As the bonding material, a solder alloy, a conductive adhesive, a metal such as Au, or the like can be used. When mounting an optical semiconductor element, an image processing device or the like is used so that the electrode is bonded to the first conductor pattern and the light emitting point is optically coupled to the optical path conversion surface via the light propagating body. It is precisely positioned at a predetermined position.

  A current is applied to the optical semiconductor element 18 in the forward direction from the anode electrode to the cathode electrode through the conductor patterns 17a and 17b. Thereby, light is emitted from the active region of the optical semiconductor element 18 which is a light emitting device.

  The optical transmission substrate constituting the optical module is provided with a core portion 12A at a position where the light emitting point of the optical semiconductor element 18 faces. The light propagating body 3 configured by connecting the refractive index distribution bodies is provided so as to penetrate the optical transmission substrate 1 between the light emitting point of the optical semiconductor element 18 and the optical path conversion surface 11C2. The light propagating body 3 of each optical transmission substrate is sized so as to have a sufficiently large diameter with respect to the size of the light emitting point of the optical semiconductor element 18 and the emitted light emitted therefrom. The light propagating body 3 has a size corresponding to the optical path conversion surface 11C2.

  When the optical semiconductor element 18 is a surface-receiving device, the optical path of the signal light is in the reverse direction. That is, the signal light that has propagated through the optical waveguide 10 </ b> C exits from the core portion, is reflected by the optical path conversion surface 11 </ b> C <b> 2, undergoes optical path conversion, and enters the light propagation body 3. The signal light reaches the active region of the surface light receiving device 18 such as a surface light receiving photodiode and is received.

  Here, in the optical module 20 of the present invention, when the optical semiconductor element 18 is a surface-emitting laser diode or a surface-receiving photodiode, it is only necessary to mount the active region of these devices on the substrate so as to face each other. Since the coupling can be easily configured, a highly efficient optical coupling structure can be easily realized without using special parts.

  As an application example of the optical module 20 of FIG. 19 or FIG. 20, an optical semiconductor element of a surface-emitting type device and an optical semiconductor element of a surface-receiving type device are mounted and fixed on one surface of the optical transmission board 1, respectively. In the optical transmission substrate 1, a light propagating body 3 is provided in the optical transmission substrate 1 so as to correspond to the optical semiconductor element and optically coupled through an optical waveguide provided on the other surface of the optical transmission substrate 1. Thus, it is possible to transmit a good signal light.

  19 and 20 uses the light propagating body 3 described in FIG. 1 as the light propagating body 3, but other light propagating bodies may be used, for example, the light propagating body 3 in FIG. The light propagating body 3 in FIG. 7, the light propagating body 23 in FIG. 7, the light propagating body 3 in FIG. 11, the light propagating body 3 in FIG.

The optical module of the present invention may use the multilayer optical transmission board instead of the optical transmission board. Specific examples of the multilayer optical transmission board include, but are not limited to, FIG. 9 or FIG. 10. According to an example of the embodiment of the optical module of the present invention shown in FIG. 19 or FIG. For example, the signal light that propagates through the peripheral part having a lower refractive index than the core part and is emitted as noise is reduced, so that the reception level on the receiving side is improved, thereby increasing the speed and error rate between the optical semiconductor elements. Small good information access.

It is principal part sectional drawing which shows typically an example of embodiment of the optical transmission board | substrate of the 1st aspect of this invention. It is principal part sectional drawing which shows typically an example of embodiment of the manufacturing method of the optical transmission board | substrate shown in FIG. It is principal part sectional drawing which shows typically an example of embodiment of the optical transmission board | substrate of the 1st aspect of this invention. FIG. 4 is a main part sectional view schematically showing an example of an embodiment of a manufacturing method for the optical transmission board shown in FIG. 3. It is principal part sectional drawing which shows typically an example of embodiment of the optical transmission board | substrate of the 1st aspect of this invention. (A)-(g) is principal part sectional drawing which shows typically an example of embodiment of the manufacturing method in the optical transmission board | substrate shown in FIG. 5 for every process. It is principal part sectional drawing which shows typically an example of embodiment of the optical transmission board | substrate of the 2nd aspect of this invention. (A)-(e) is principal part sectional drawing which shows typically an example of embodiment of the manufacturing method in the optical transmission board | substrate shown in FIG. 7 for every process. It is principal part sectional drawing which shows typically an example of embodiment of the multilayer optical transmission board | substrate of this invention. It is principal part sectional drawing which shows typically an example of embodiment of the multilayer optical transmission board | substrate of this invention. It is principal part sectional drawing which shows typically an example of embodiment of the optical transmission board | substrate of the 1st aspect of this invention. (A)-(f) is principal part sectional drawing which shows typically an example of embodiment of the manufacturing method in the optical transmission board | substrate shown in FIG. 11 for every process. (A)-(i) is principal part sectional drawing for every process which shows typically an example of embodiment of the manufacturing method in the 1st optical transmission board | substrate of this invention shown in FIG. 11 for every process. It is principal part sectional drawing which shows typically an example of embodiment of the 1st optical transmission board | substrate of this invention. (A)-(h) is principal part sectional drawing which shows typically an example of embodiment of the manufacturing method in the optical transmission board | substrate shown in FIG. 14 for every process. It is principal part sectional drawing which shows typically an example of embodiment of the optical transmission board | substrate of this invention which further has an optical waveguide. It is principal part sectional drawing which shows typically an example of embodiment of the composite-light transmission board | substrate of this invention. It is principal part sectional drawing which shows typically an example of embodiment of the composite-light transmission board | substrate of this invention. It is principal part sectional drawing which shows typically an example of embodiment of the optical module of this invention. It is principal part sectional drawing which shows typically an example of embodiment of the optical module of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical transmission board | substrate 2 Substrate 2A One main surface 2B of the substrate The other main surface 3 of the substrate 3 Light propagating body 3A First end surface 3B Second end surface 4 First region 5 Second region 5A Two regions 6 Boundary portion 6A Columnar boundary portion 7 Through hole 8 First transparent resin 9 Second transparent resin 10A Optical waveguide 10A1 formed in 2A Upper clad portion 10A2 in optical waveguide 10A Core in optical waveguide 10A Part 10A3 Optical waveguide 10B1 formed in the lower cladding part 10B 2B in the optical waveguide 10A Lower cladding part 10B2 in the optical waveguide 10B Core part 10B3 in the optical waveguide 10B Upper cladding part 10C in the optical waveguide 10B In the optical module 20 Base 11A2 Base 11A composed of a translucent member formed in the optical waveguide 11A1 2A Base 11B2 formed of a translucent member formed on the reflection surface 11B12 2B formed on the reflection surface 11C2 formed on the substrate 11B1 Optical path conversion surface 12A Core portion 12B in the first region 4 Core portion 13A in the second region Cladding portion 13B in the first region 14 Cladding portion 14 in the second region Light reflecting film 15 Translucent member 16 Gap portion 17 Conductive pattern 18 Optical semiconductor element 19 Central axis 20 of through hole Optical module 22 Second substrate 22A Second Surface 23 of substrate facing light transmission substrate 1 Light propagating body 30 Photomask 32 Core portion 33 Cladding portion 34 Recess 40 Optical waveguide 40A formed on surface 22A Upper clad portion 40B in optical waveguide 40 Core portion in optical waveguide 40 40C Lower clad part 41 in optical waveguide 40 Optical path changer 41A Optical path changer Reflective surface at 41

Claims (17)

A first region penetrating between the two principal surfaces, the central axis being perpendicular to at least one principal surface of the two principal surfaces, and monotonously decreasing from one principal surface to the other principal surface; A substrate having a through hole connected to the second region other than the region at the boundary;
A light propagating body having a cladding portion provided inside the through hole of the first region, and a core portion having a first end surface on the one main surface side and having a higher refractive index than the cladding portion. And comprising
An optical transmission board in which the core portion is in contact with the inner periphery of the boundary portion.
  2. The optical transmission board according to claim 1, wherein the second region has a core portion having a refractive index higher than that of a peripheral portion in a radial direction of the through hole. The optical transmission board according to claim 1, wherein the second region of the through hole is filled with the same material as the core portion. A substrate having a through-hole penetrating between both main surfaces and having a central axis perpendicular to at least one main surface of the two main surfaces;
Provided inside the through-hole, comprising a cladding portion, and a first end surface on one main surface side of the substrate and a second end surface on the other main surface side of the substrate, and having a refractive index higher than that of the cladding portion. A light having a raised core portion, the through-hole having a monotonically decreasing diameter from the first end surface toward the second end surface, and an inner periphery of the second end surface being in contact with the core portion Transmission board. The through hole is on a surface, a metal film or a light transmission substrate according to any one of claims 1 to 4 further comprising a film of lower refractive index than said light propagating body. In the end of the light propagating body, further comprising a recess recessed into the through-hole from the opening periphery of the through-hole,
Wherein provided in the recess, the light transmission substrate according to any one of claims 1 to 5 refractive index further comprises a transparent member or the refractive index of the core portion. At least one of the formed on the main surface, the light transmission substrate according to any one of claims 1 to 6 further comprising the light propagating body optically coupled to optical waveguides of the substrate. A process of forming a through hole having a central axis perpendicular to at least one main surface of both main surfaces by drilling so that the diameter monotonously decreases from both main surfaces of the substrate toward the inside of the substrate. A and
Step B of filling the first transparent resin having photocurability into the hole portion from the smallest diameter portion having the smallest diameter to one main surface among the through holes,
By exposing and curing the first transparent resin from the other main surface side, the core portion composed of the first transparent resin from the minimum diameter portion to the one main surface side in the through hole. Forming step C;
In the through hole, a step D of forming a peripheral portion having a lower refractive index than the core portion around the core portion;
A method of manufacturing an optical transmission board including: After step B, step E providing a recess at the end of the first transparent resin provided in the through hole on the one main surface side;
After the step C and the step E, a step F in which a light-transmitting member having a refractive index equal to or higher than the refractive index of the core portion is filled in the recess.
The manufacturing method of the optical transmission board | substrate of Claim 8 which further contains these. One of the main surfaces of the substrate is drilled so that the diameter decreases monotonically from one main surface to the other main surface, and the central axis is perpendicular to at least one of the main surfaces. Step A ′ for forming two through holes;
Step B ′ for filling the through hole with a first transparent resin having photocurability;
By exposing and curing the first transparent resin from the other main surface side, a core portion composed of the first transparent resin is formed from the one main surface side to the other main surface side. Step C ′ to be performed,
In the through hole, a step D ′ for forming a peripheral portion having a lower refractive index than the core portion around the core portion;
A method of manufacturing an optical transmission board including: After step B ′, providing step E ′ with a recess at the end of at least one main surface of the first transparent resin provided in the through hole;
After the step C ′ and the step E ′, a step F ′ of filling a translucent member having a refractive index equal to or higher than the refractive index of the core portion in the concave portion;
The method for manufacturing an optical transmission board according to claim 10 , further comprising: The optical transmission substrate according to any one of claims 1 to 7 is stacked, end faces of the light propagating member face each other in each of the light transmission substrate of two adjacent layers, and is optically coupled Multi-layer optical transmission board. An optical transmission board according to any one of claims 1 to 7 ,
A conductor pattern formed on one surface of the optical transmission board;
An opto-electronic hybrid board comprising: The opto-electronic hybrid board according to claim 13 ,
An optical semiconductor element electrically connected to the conductor pattern on one surface of the opto-electronic hybrid substrate;
An optical module comprising: The multilayer optical transmission board according to claim 12 ,
A conductor pattern formed on one exposed surface of the multilayer optical transmission board;
An opto-electronic hybrid board comprising: The multilayered optoelectronic hybrid substrate according to claim 15 ,
An optical semiconductor element electrically connected to the conductor pattern on one exposed surface of the opto-electronic hybrid board; and
An optical module comprising: An optical transmission substrate according to any one of claims 1 to 7, and a second substrate disposed parallel to the optical transmission substrate, is formed on the surface facing the optical transmission substrate in the second substrate An optical waveguide,
A composite optical transmission board in which a core portion of the light propagating body in the optical transmission board is optically coupled to the optical waveguide.

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