JP5328095B2 - Optical transmission board, opto-electronic hybrid board, optical module, and optoelectric circuit system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable optical transmission substrate of which optical transmission direction can be fully efficiently changed in the in-plane direction and vertical direction and which can easily be manufactured, and to provide an optoelectronic hybrid substrate/wiring board and an optical module. <P>SOLUTION: The optical transmission substrate is equipped with: a substrate 1 composed of a recess 2b formed on one primary face and an optical transmission hole 4 which penetrates from the bottom face of the recess 2b through the other primary face and is opened at the bottom face of the recess 2b; an optical waveguide 5 formed on the other primary face of the substrate 1; and an optical path conversion body 6 which is optically coupled to both the optical transmission hole and the optical waveguide so as to convert an optical transmission direction between the optical transmission hole 4 and the optical waveguide 5. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to the optical transmission board, the opto-electronic hybrid board, the optical module, and the opto-electric circuit system, in which an optical signal can be transmitted with high efficiency by shortening the optical path length between the main surfaces of the board.

  In recent years, with the improvement of information processing capability of computers, in an integrated circuit (IC) such as a semiconductor large scale integrated circuit element (LSI, VLSI) used as a microprocessor, the degree of integration of transistors has been increased. The operating speed of the IC has reached the GHz level at the clock frequency. Along with this, there has been a demand for higher density and finer electrical wiring for electrically connecting electrical elements.

  However, increasing the density and miniaturization of electrical wiring tends to cause crosstalk and propagation loss of electrical signals. Therefore, electrical signals input to and output from semiconductor devices are converted to optical signals, and the optical signals are mounted. An optical transmission technique in which an optical wiring such as an optical waveguide formed on a substrate is transmitted has been studied.

  In the optical transmission technology, a vertical cavity surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser) that is advantageous for power saving and surface arraying is used as a photoelectric conversion unit that performs conversion between an optical signal and an electrical signal. ) And a surface light receiving type semiconductor light receiving element (PD: Photo Diode). In addition, as an optical wiring for propagating an optical signal, an optical waveguide or the like in which a high refractive index region serving as a core portion is covered with a material having a lower refractive index than the core is used.

  In general, the optical semiconductor such as a VCSEL is mounted on the surface of a substrate, and the optical waveguide is formed in a direction parallel to the surface of the substrate. In the optical coupling structure between these optical semiconductor elements and the optical waveguide, the input / output direction of the signal light and the optical waveguide are in a substantially crossing relationship, so that various optical signals can be transmitted in order to achieve high-efficiency optical signal propagation. Proposals have been made.

For example, in order to optically couple between an optical semiconductor element mounted on one main surface and an optical waveguide provided on the other main surface, from one main surface side to the other main surface side An optical module comprising an optical transmission hole penetrating the optical path and an optical path changing body that changes the optical path direction to the lower surface position of the optical transmission hole is disclosed (see Patent Documents 1 and 2).
JP 2000-81524 A JP 2004-54003 A

  However, in the optical modules described in Patent Documents 1 and 2, since light spreads through the optical transmission hole, it is difficult to achieve sufficiently high-efficiency optical signal propagation during optical transmission, particularly when changing the optical transmission direction. was there. Also, in order to prevent the spread of light, even if a transparent resin is provided in the light transmission hole or the like, even if the transparent resin is filled, the spread of light cannot be sufficiently suppressed. Propagation could not be achieved.

  The present invention has been devised to solve the above-described problems in the prior art, and its purpose is to convert the optical transmission direction between the in-plane direction and the vertical direction of the substrate sufficiently efficiently. An optical transmission board, an opto-electronic hybrid board line board, an optical module, and a photoelectric circuit system that can be manufactured easily and can be easily manufactured.

According to a first aspect of the present invention, there is provided a recess for housing and providing an optical semiconductor element, a second recess provided on the other main surface, and a bottom surface of the recess. To the bottom surface of the second recess, and a substrate having an optical transmission hole that opens to the bottom surface of the recess and the bottom surface of the second recess, and the entirety in the second recess An optical waveguide that is accommodated and has a thickness smaller than the depth of the second recess, and the optical transmission hole and the optical waveguide are changed in order to change the optical transmission direction between the optical transmission hole and the optical waveguide. The present invention relates to an optical transmission board comprising an optical path changer optically coupled to both.

  It is preferable that a transparent resin capable of transmitting light is provided in the light transmission hole.

  The present invention provides an optical transmission board according to the first aspect or an optical transmission board according to the second aspect, and an electric wiring layer comprising an exposed portion at least partially exposed on the bottom surface of the recess and the one main surface. And an opto-electronic hybrid board.

  The present invention relates to an optical module comprising: the opto-electronic hybrid substrate; and an optical semiconductor element mounted on an exposed portion of the electrical wiring layer in the recess and optically coupled to the optical transmission hole.

  The substrate has two sets of the recess and the light transmission hole, and the optical semiconductor element is a light emitting element and a light receiving element, and is mounted in each of the two sets of recesses, and the optical path conversion There are two sets of bodies, one of which is one end of the optical waveguide and the light emitting element, and the other end is optically connected to the other end of the optical waveguide and the light receiving element through the two sets of optical transmission holes. It is preferable to have optical transmission paths that are coupled to each other.

  The present invention relates to a photoelectric circuit system comprising the optical module and a semiconductor integrated circuit element mounted on an exposed portion of the electrical wiring layer on the one main surface.

  The semiconductor integrated circuit element is of two types and is configured to transfer data between the two. The substrate is further provided with one set of the optical transmission paths, and these two sets of optical transmission paths. Preferably, the data transfer is performed by transferring light in different directions.

  It is preferable that the apparatus further includes a cooling device provided on the semiconductor integrated circuit element so as to cover the optical semiconductor element and dissipating heat generated by the semiconductor integrated circuit element.

  According to the optical transmission board in the first aspect of the present invention, the optical transmission board is provided on one main surface side, and penetrates between the concave portion for providing the optical semiconductor element and the bottom surface of the concave portion to the other main surface side. A substrate having an optical transmission hole opened in a bottom surface of the concave portion, an optical waveguide provided on the other main surface side of the substrate, and an optical transmission direction between the optical transmission hole and the optical waveguide In order to reduce the optical path length between the main surfaces of the substrate by comprising an optical path changer optically coupled to both the light transmission hole and the optical waveguide, It is possible to suppress the spread of light, and to achieve a sufficiently high-efficiency propagation of an optical signal, particularly when changing the direction of optical transmission.

  Preferably, in the optical transmission board of the present invention, a second recess is further provided on the other main surface side, and the optical transmission hole is opened in a bottom surface of the second recess, and further, the second recess By providing the optical waveguide in the recess, the optical transmission direction between the main surfaces of the substrate can be further shortened.

  Further, according to the optical transmission board in the third aspect of the present invention, the optical transmission hole penetrating from one main surface side to the other main surface side, the other main surface side is formed, In order to change the light transmission direction between the light transmission hole and the optical waveguide, the optical waveguide formed in the concave portion, a substrate having a concave portion in which the optical transmission hole is opened on the bottom surface, The optical path changer optically coupled to both the light transmission hole and the optical waveguide can reduce the optical path length between the main surfaces of the substrate, thereby suppressing the spread of light. In particular, it is possible to achieve sufficiently high-efficiency propagation of an optical signal when converting the optical transmission direction.

  In the optical transmission board of the present invention, preferably, the optical transmission hole is provided with a transparent resin capable of transmitting light, thereby reducing light reflection at the opening of the optical transmission hole, and further In addition, light scattering at the optical path changer can be reduced, and light crosstalk with other adjacent cores can be reduced.

  In addition, according to the opto-electronic hybrid board of the present invention, the optical transmission board and the electric wiring layer including an exposed portion at least partially exposed on the bottom surface of the recess and the one main surface are provided. Thus, an optical semiconductor element, a semiconductor integrated circuit, and the like can be mounted on the bottom surface of the recess and the one main surface, respectively. Further, since the optical path is already secured, the shape of the electric wiring layer is not restricted by the optical path.

  Preferably, in the opto-electronic hybrid board according to the present invention, the exposed portion exposed on the one main surface of the exposed portions is provided on the one main surface and around the concave portion, so that it is provided between the electric wiring layers. The length can be further shortened.

  The optical module according to the present invention includes an opto-electronic hybrid board and an optical semiconductor element mounted on the exposed portion of the electrical wiring layer in the recess and optically coupled to the optical transmission hole. Thus, the optical semiconductor element can be accommodated in the recess, and the optical module can be miniaturized.

  In the optical module of the present invention, preferably, the substrate has two sets of the recess and the light transmission hole, and the optical semiconductor element includes two types of a light emitting element and a light receiving element, and the two sets of recesses are in the two sets of recesses. The optical path changers are mounted in two sets, one of which is one end of the optical waveguide and the light emitting element, and the other is the other end of the optical waveguide and the light receiving element. By having an optical transmission path optically coupled through a pair of optical transmission holes, the optical transmission path can be shortened and light transmission from the light emitting element to the light receiving element on the same substrate can be made possible. .

  According to the photoelectric circuit system of the present invention, the optical module includes a semiconductor integrated circuit element mounted on the exposed portion of the electrical wiring layer on the one main surface, thereby providing an optical circuit. Data transfer of the semiconductor integrated circuit element can be performed by transmission.

  In the optoelectric circuit system according to the present invention, preferably, the semiconductor integrated circuit element is of two types and is configured to transfer data between the two, and the substrate further includes the optical transmission path. The data transfer is performed by transferring light in a direction different from each other between these two sets of optical transmission paths, so that the optical transmission path can be shortened and bidirectional between the semiconductor integrated circuits on the same substrate. Data transfer can be enabled.

  Preferably, the photoelectric circuit system of the present invention further includes a semiconductor integrated circuit element mounted on the exposed portion of the electric wiring layer on the one main surface, and is provided on the semiconductor integrated circuit element. Since the semiconductor integrated circuit device further includes a cooling device that dissipates heat, a step is provided between the semiconductor integrated circuit arrangement position and the optical semiconductor element arrangement position. The influence of the temperature on the optical semiconductor element due to the integrated circuit can be suppressed, and damage to the optical semiconductor element due to the cooling device can be prevented when the cooling device is mounted.

  The optical transmission board, the opto-electronic hybrid board, the optical module, and the photoelectric circuit system in the first aspect, the second aspect, and the third aspect will be described with reference to the drawings. However, these drawings are only examples of the embodiments. However, the present invention is not limited to them.

[Optical Transmission Board in First Aspect]
In FIG. 1, 1 is a substrate, 2a (2a1, 2a2, 2a3) is one main surface of the substrate 1, and 2b (2b1, 2b2) is a recess provided on one main surface side of the substrate 1 (first recess). ), 3a (3a1, 3a2) is the other main surface of the substrate 1, 3b is a recess (second recess) provided on the other main surface side, 4 (4a, 4b) is an optical transmission hole, and 5 is a light guide. Waveguides and 6 (6a, 6b) represent optical path changers, respectively.

  Here, the above-mentioned “one main surface side of the substrate 1” refers to a surface that faces the one main surface 2a together with the one main surface 2a and is substantially in the same direction. For example, in FIG. Indicates the bottom surface of the recess 2b.

  As the board | substrate 1, the printed wiring board which consists of an epoxy resin, a ceramic, etc. generally used is mentioned, for example. Among them, a printed wiring board having a symmetrical layer structure in which a resin insulating layer having the same thickness is formed on both sides is preferable because the mechanical strength is large and it is possible to effectively prevent the warpage of the board due to heat. It is more preferable that the resin insulating layers on both sides have the same thickness. The thickness of the substrate can be 0.5 to 1.5 mm.

  Further, as the substrate 1, specifically, a multilayer substrate can be mentioned. Here, the multilayer substrate may be any substrate in which a plurality of electrical wiring layers and insulating layers are alternately stacked. For example, a substrate including a core substrate and a build-up layer formed on the surface side of the wiring substrate may be used. included. Here, the build-up layer is a multilayer substrate in which electrical wiring layers and insulating layers are alternately stacked, and the core substrate is a single layer on which the build-up layer is provided and supports the build-up layer. Say.

  As shown in FIG. 1, the optical transmission board of the present invention has a main body of a board 1 having one main surface 2a and the other main surface 3a. The substrate 1 includes a first recess 2b, a second recess 3b, and an optical transmission hole 4 (4a, 4b) penetrating from the first recess 2b to the second recess 3b. .

  The first recess 2b has such a size that an optical semiconductor element such as a light emitting element or a light receiving element can be provided therein. Specifically, the depth of the 1st recessed part 2b is 100-500 micrometers. By providing the optical semiconductor element inside, the light transmission distance from one main surface side of the substrate 1 to the other main surface side can be shortened, and a semiconductor integrated circuit element is provided on one main surface 2a. In this case, since there is a step between the arrangement position of the semiconductor integrated circuit element and the arrangement position of the optical semiconductor element, the temperature change of the optical semiconductor element due to the semiconductor integrated circuit element can be greatly suppressed. In addition, by providing the first concave portion 2b, it is possible to easily produce an optical transmission hole having a small hole diameter, which is difficult to produce when the thickness of the substrate is large.

  The first recess 2b may have a size capable of providing a VCSEL driver, a TIA (transimpedance amplifier), and the like together with the optical semiconductor element.

  For example, when the substrate 1 is a multilayer substrate, the first concave portion 2b is manufactured by a method of punching the multilayer substrate for a necessary number of layers before stacking, or a method of cutting the multilayer substrate by cutting after manufacturing the multilayer substrate. Etc. In particular, in the case where the concave portion is formed over a wide area, a method by die cutting is preferable from the viewpoint of manufacturing cost and tact time. When the multilayer substrate is a multilayer substrate composed of a core layer and a buildup layer, the first recess 2b is formed by patterning the buildup layer.

  As shown in FIG. 1, the optical transmission board of the present invention is provided with the second recess 3b on the other main surface 3a opposite to the one main surface 2a on which the first recess 2b is provided. It is preferable that the light transmission hole 4 is opened at the bottom surface in the concave portion of the second concave portion 3b, and an optical waveguide 5 is further provided so as to be optically coupled to the light transmission hole 4. Is preferred. By doing so, the transmission distance of light from one main surface side of the substrate 1 to the other main surface side can be shortened. Further, when an optical semiconductor element is further provided on the optical transmission board of the present invention to form an optical module, the other main surface 3a is protected while protecting the optical waveguide 5 when the optical module is mounted on a multilayer wiring board (motherboard). Enables stable implementation.

  The method for producing the second recess 3b can be performed in the same manner as the method for producing the first recess 2b described above.

  In FIG. 1, the light transmission hole 4 penetrates from the bottom surface of the first recess 2b to the other main surface side (in this case, the bottom surface of the second recess 3b) to transmit light. Here, “the other main surface side” refers to a surface which faces the other main surface 3a together with the other main surface 3a and faces substantially the same direction. For example, in FIG. 1, the bottom surface of the second recess 3b. Say.

  The light transmission hole 4 is opened at the bottom surface of the first recess 2b. For example, when a light emitting element is installed in the first recess 2b, light emitted from the light emitting element passes through the opening and enters the light transmission hole. By propagating, light is transmitted to the light transmission hole 4. When the light emitting element or the light receiving element is provided in the recess, the light transmission hole 4 is formed at a position facing the light emitting part of the light emitting element or the light receiving part of the light receiving element.

  Further, when the optical semiconductor element is provided in the first recess 2b, the hole diameter of the light transmission hole 4 is adjusted according to the light emission diameter or the light reception diameter of each of the light emitting element and the light receiving element and the size of the optical path changer. Determined by considering the spread. Most preferably, the hole diameter of the light transmission hole 4 corresponding to the light receiving part is smaller than that of the light receiving part, and the hole diameter of the light transmission hole 4 corresponding to the light emitting part is set larger than that of the light emitting part.

  For the formation of the light transmission hole 4, a drill or a laser used in a normal printed board drilling process is preferably used.

  The number of light transmission holes 4 opened in the bottom surface of the first recess 2b is preferably the same as the number of channels of the optical semiconductor element. For example, when a 4-channel array VCSEL is provided inside the first recess 2b, the number of light transmission holes 4 is preferably four, which is the same as the number of channels of the VCSEL. Thus, by setting the number of light transmission holes 4 to be the same as the number of channels of the optical semiconductor element, it is possible to accurately transmit an optical signal emitted or incident from each channel.

  When the hole diameter and the number of holes of the light transmission hole 4 are determined as described above, for example, when a VCSEL having a diameter of 15 μm and a pitch of 250 μm is used, the light transmission hole 4 has a diameter corresponding to the light emitting part. Four light transmission holes having the same number of holes are formed for each light emitting part with a pitch of 15 μm or more and a pitch of 250 μm, and when a light receiving part uses a PD with a diameter of 65 μm and a pitch of 250 μm, a light beam It is preferable that the transmission holes 4 have a diameter of 65 μm or less and a pitch of 250 μm, and four light transmission holes having the same number of holes are formed for each light receiving portion.

  It is preferable that a transparent resin capable of transmitting light is provided in the light transmission hole 4. The transparent resin in the light transmission hole may be a single resin having a uniform refractive index. In particular, the transparent resin is most preferably a resin whose refractive index distribution is high in the central portion and low in the peripheral portion in the radial direction. Such a concentric refractive index distribution has an optical confinement effect for confining signal light in the center. As the transparent resin, a transparent resin (hereinafter referred to as transparent resin A) having a refractive index distribution formed so as to decrease stepwise from the central portion toward the peripheral portion in the radial direction of the light transmission hole 4, or light A transparent resin (hereinafter referred to as transparent resin B) having a refractive index distribution formed so as to be gradually lowered concentrically from the central portion toward the peripheral portion in the radial direction of the transmission hole is preferable.

  The refractive index distribution of the transparent resin A and the transparent resin B is such that polysilane that causes a photo bleaching phenomenon in which the refractive index decreases when irradiated with light, or a photosensitive acrylic resin or epoxy that can be removed by developing the irradiated portion. It can be formed using a resin or the like. For example, when the photo bleaching phenomenon is used, the light transmission hole 4 is filled with polysilane, heated and cured, and then passed through a photomask (having a light shielding portion having a circular pattern with a diameter smaller than that of the light transmission hole). The refractive index distribution is formed in the transparent resin in the light transmission hole 4 by irradiating the ultraviolet light to lower the refractive index of the non-irradiated portion of the ultraviolet light and finally performing the post-baking.

  In the case of using an ultraviolet curable acrylic resin or epoxy resin, the light transmission hole 4 is filled with these photosensitive polymer materials and cured by heating, and then a photomask (a circular shape having a diameter smaller than that of the light transmission hole). The portion of the light transmission hole 4 that has been removed by the development (light transmission) is removed by performing development by irradiating ultraviolet light through the light transmitting portion of the pattern). In the center of the hole), a material having a higher refractive index than that of the first filling material is filled, cured by irradiating with ultraviolet light without using a photomask, and finally post-baking is performed. A refractive index distribution is formed in the transparent resin.

  The optical waveguide 5 is provided in parallel to the surface on the other main surface side of the substrate 1 and plays a role of transmitting light. The optical waveguide 5 includes a core portion and a clad portion that surrounds the core portion and has a refractive index smaller than that of the core portion. In the case of FIG. 1, the core part is a part located on the center axis side of the optical waveguide 5, and the clad part is a part located so as to wrap around the core part. Further, in the cladding part, the side closer to the substrate 1 is the lower cladding part, and the side farther from the substrate 1 is the upper cladding part. The optical waveguide 5 having the lower clad part and the upper clad part can achieve good light propagation by adjusting the refractive indexes of the core part and the clad part. For example, in the case of a multi-mode optical waveguide, the shape and dimensions of the core portion and the clad portion of the optical waveguide are set so that the thickness of the lower clad portion and the upper clad portion is the core when the thickness of the core portion is about 50 μm. The optical waveguide 5 having a thickness of about 100 μm can be obtained as about 25 μm, which is half of the portion.

  The optical waveguide 5 is preferably provided in the second recess 3b. And thereby, the transmission distance of the light from the one main surface side of the board | substrate 1 to the other main surface side can be shortened. Further, when an optical semiconductor element is further provided on the optical transmission board of the present invention to form an optical module, the other main surface 3a is protected while protecting the optical waveguide 5 when the optical module is mounted on a multilayer wiring board (motherboard). Enables stable implementation.

  In addition to the method of forming the optical waveguide 5 in the second recess 3b, only the optical waveguide 5 may be separately manufactured and bonded to the recess 3a on the second surface of the substrate 1. In order to bond the optical waveguide 5 to the concave portion of the second surface of the substrate 1, a marker is prepared and the position of the light transmission hole 4 and the position of the core portion of the optical waveguide 5 are accurately aligned.

  Examples of a method for producing the optical waveguide 5 having a core part include a direct exposure method, a refractive index change method (photo bleaching method), and a reactive ion etching method. Any method can be used, but the simplest and most stable manufacturing method is a direct exposure method. In particular, the method of forming directly on the substrate 1 can determine the core position while confirming the position of the light transmission hole 4 by photolithography, and the alignment between the light transmission hole 4 and the core portion of the optical waveguide 5 is simple. Become.

  Examples of materials that can be manufactured by the direct exposure method include photosensitive epoxy resins, acrylic resins, and polyimide resins. In the direct exposure method, a necessary pattern can be obtained by applying, exposing, and developing materials corresponding to the core portion and the clad portion. For example, if a negative photosensitive epoxy resin is used, the exposed portion of the resin is cured and exposed by applying a material and preparing and exposing a photomask that exposes the necessary areas. By removing the unexposed resin by development, a desired pattern can be obtained. By applying this method to both the lower clad part and the upper clad part and the core part, the optical waveguide 5 can be formed only at a necessary place in the entire substrate.

  The above-described polymer material is suitable in that it can be formed on various substrates 1 because the optical waveguide 5 can be manufactured by a low-temperature process, can easily cope with an increase in area, and can be manufactured at low cost. It is. In particular, when an epoxy resin is used, since it is a material of the same series as a glass epoxy substrate generally used as a substrate, adhesion is good, there is no defect such as peeling, and reliability is high. In addition to the photosensitive epoxy, photosensitive polyimide is also preferable because it has high durability and has been conventionally used as a protective film or a sealing resin.

  The optical path changer 6 is optically coupled to both the optical transmission hole 4 and the optical waveguide 5, and thereby converts the light transmission direction between the optical transmission hole 4 and the optical waveguide 5. Have a function. Specifically, since the optical path changing body 6 is a light reflecting surface having a constant inclination angle, the incident direction of light can be converted into the reflecting direction, and thereby the light transmission holes 4 having different optical path directions. The optical waveguide 5 can be optically coupled.

  In FIG. 1, the optical path changer 6 is a light reflecting surface obtained by obliquely cutting off a part of the optical waveguide 5, but may be made of a member different from the optical waveguide 5.

  In FIG. 1, the optical path changer 6 (6 a, 6 b) is formed at a location corresponding to the opening position of the optical transmission hole 4 after the optical waveguide 5 is formed. As a method of forming the optical path changer 6, it is generally formed by grooving with a dicing saw using a diamond blade whose tip is processed at 45 degrees or 90 degrees. In addition to this, there are a method of forming a slope by patterning the optical waveguide 5 by using a gray mask or oblique exposure, and a method of using a marking machine used for cutting a printed circuit board. However, stability, processing accuracy, and productivity are improved. When considered, a dicing saw is most preferable.

  The optical path changer 6 has a slope formed on the intermediate surface of the optical waveguide 5, or gold (Au), silver (Ag), platinum (Pt), aluminum (Al), copper (Cu), or the like. A film having a high reflectance with respect to the light guided through the optical waveguide 5 can be formed on the surface thereof.

  FIG. 2 shows another example of the optical transmission board according to the first aspect of the present invention. The optical transmission board in FIG. 2 differs from that in FIG. 1 in that an optical waveguide is provided not on the second recess 3b but on the other main surface 3a. Also for the optical transmission substrate in FIG. 2, the optical path length between the principal surfaces of the substrate can be shortened, and high coupling efficiency can be obtained.

[Photoelectric mixed substrate of the present invention]
As shown in FIG. 3, the opto-electronic hybrid board of the present invention is obtained by further providing an electrical wiring layer with respect to the optical transmission board of FIG. 1 of the present invention. Most of the electric wiring layers are formed in the printed wiring board in the substrate 1 (not shown).

  In FIG. 3, the exposed portion 7 a (7 a 1, 7 a 2) of the electric wiring layer is exposed on one main surface 2 a and the exposed portion 7 b (7 b 1, 7 b 2) is exposed on the bottom surface of the first recess 7. By having the exposed portions 7a and 7b as described above, it is possible to mount a semiconductor integrated circuit element on the exposed portion 7a and an optical semiconductor element on the exposed portion 7b.

  In the electric wiring layer, in addition to the exposed portions 7a and 7b on one main surface side, an exposed portion of the electric wiring layer is also formed on the other main surface 3a (not shown). It is electrically connected to the exposed portions 7a and 7b on the main surface side. Since the exposed portion of the electric wiring layer is also formed on the other main surface 3a in this way, when the substrate 1 is mounted as a daughter board on another printed circuit board (motherboard), the electric power of the second surface 3 Electrical connection can be made using the wiring 5.

  The substrate 1 is not limited to a printed wiring board, but may be a ceramic wiring board using alumina or the like as an insulating layer inside the board, or a board in which electric wiring is formed on silicon, glass, or the like. Among these, a glass epoxy wiring board is suitable as a versatile one that can be manufactured at low cost.

  The wiring pattern of the electric wiring layer in the substrate 1 is formed by a photolithography process or an etching process of copper foil or resin with copper foil during a normal printed circuit board manufacturing process.

  On the electrical wiring layer 5, a solder resist layer (not shown) may be formed to serve as both an electrical insulating layer for the electrical wiring layer 5 and protection of the electrical wiring layer 5. In that case, an opening is provided on the solder resist at a minimum necessary position for mounting the element, and the element is mounted on the electric wiring layer 5 in the opening using solder or the like. The inside of the recess 2a on the first surface of the substrate 1 does not require a solder resist and may have a shape in which the electric wiring layer 5 is exposed.

[Optical module]
As shown in FIG. 4, the optical module of the present invention further comprises optical semiconductor elements such as a light emitting element 8 and a light receiving element 9 with respect to the opto-electronic hybrid substrate of FIG.

  The optical module shown in FIG. 4 has an optical transmission path through which light can be transmitted from the light emitting element 8 to the light receiving element 9. The optical signal emitted from the light emitting element 8 is transmitted to the optical waveguide 5 through the optical transmission hole 4a, converted in the light transmission direction by the optical path conversion body 6a, and then transmitted to the optical waveguide 5b. After the transmission direction is converted, the light enters the light receiving element 9 through the light transmission hole 4b.

  In the optical signal transmission as described above, the optical module shown in FIG. 4 has two types of optical path changers 6a and 6b, and one optical path changer 6a transmits light with one end of the optical waveguide 5 and the light emitting element 8. This can be achieved by optically coupling through the hole 4a, and by optically coupling the other optical path changer 6b with one end of the optical waveguide 5 and the light receiving element 9 through the optical transmission hole 4b. .

  Furthermore, as shown in FIG. 4, the light path 8 from the light emitting element 8 to the light receiving element 9 can be shortened by mounting the light emitting element 8 and the light receiving element 9 in the two sets of recesses 2b1 and 2b2, respectively. it can. Further, as shown in FIG. 4, the two sets of recesses 2 b 1 and 2 b 2 may be further provided with a VCSEL driver 10 together with the light emitting element 8 and a TIA 11 together with the light receiving element 9.

  As described above, the optical module of the present invention has been described with reference to FIG. 4 in which the light emitting element and the light receiving element are on the same substrate. However, in the optical module of the present invention, the light emitting element and the light receiving element are respectively on the same substrate. Some are not inside. In FIG. 4, the concave portion provided with the light emitting element and the concave portion provided with the light receiving element are described as examples. However, in the optical module of the present invention, the concave portion in which the light emitting element and the light receiving element are the same. Also included in the above.

[Optoelectric circuit system]
Further, as shown in FIG. 5, the opto-electric circuit system of the present invention further comprises a CPU 12 (central processing unit) and a GPU 13 (graphics processing unit) for the opto-electronic hybrid substrate of FIG. 4 of the present invention. It is a thing.

  A semiconductor integrated circuit such as the CPU 12 or the GPU 13 becomes high temperature during operation and emits a large amount of heat, and in particular, tends to cause a temperature change in the optical semiconductor element. However, as shown in FIG. By being mounted in the first recess 2b, the heat from the semiconductor integrated circuit is shielded by the step, and the effect that the temperature change of the optical semiconductor element can be prevented is obtained.

  In FIG. 5, only one set of optical transmission paths from the light emitting element 8 to the light receiving element 9 described in the description of [Optical module] is shown, but in the present invention, another optical transmission path is provided. It may be assembled. When the photoelectric circuit system of the present invention has two types of semiconductor integrated circuit elements such as a CPU and a GPU and they transfer light in different directions, data transfer is performed in both directions. Can be done.

  Further, as described above, since a semiconductor integrated circuit tends to release a large amount of heat, a huge cooling device such as a heat sink is generally provided on the semiconductor integrated circuit. When the cooling device is mounted on the optical module, the optical semiconductor element tends to be easily damaged by the cooling device. In contrast, as shown in FIG. 6, in the optical module of the present invention, since the optical semiconductor element is provided in the first recess 2a, the possibility of damage by the heat sink 14 is reduced, and the heat sink 14 Since the optical semiconductor element is covered, it is possible to prevent the incidence of an optical signal that becomes noise from the outside.

  The optical semiconductor element can protect the element from external variation factors such as temperature change and vibration by fixing with underfill using the concave portion 2a on the first surface and then molding with resin. Here, as the underfill, a resin having a transparent insulating property is used, and specific examples include an epoxy resin.

[Optical Transmission Board in Second Aspect]
FIG. 7 shows a specific example of the optical transmission board in the second mode. 15 is a solder as mounting means, 16 is an underfill, 17 is a second optical transmission board, 18 is an optical waveguide provided on the second optical transmission board 17, and 19 is an optical path changer provided on the optical waveguide 18. Indicates.

  The optical transmission board in the second mode is mounted and used on another board (hereinafter, second optical transmission board 17). In addition, since the recessed part and optical transmission hole which the board | substrate in a 2nd aspect provides are the same as that of the board | substrate in the optical transmission board | substrate in a 1st aspect mentioned above, description is abbreviate | omitted.

  In FIG. 7, the second optical transmission board 17 has an optical path changer 19 as a place where light can be input and output. Here, the place where light can be input and output is only required to be able to input or output light to the light transmission hole 4, and may be, for example, an optical semiconductor element in addition to the optical path changer 19. The optical path changer 19 may be a light reflecting surface obtained by obliquely cutting a part of the optical waveguide 18, or may be formed of a member different from the optical waveguide 18.

The means for mounting the optical transmission board in the second aspect is to mount the optical transmission board on the second optical transmission board 17 so that the optical path changer 19 and the optical transmission hole 24 are optically coupled. The optical transmission board is electrically connected to the second optical transmission board 17.

  Specific mounting means include, for example, BGA (Ball Grid Array), PGA (Pin Grid Array), LGA (Land Grid Array), etc. In the case of FIG. 7, BGA using solder balls 15 is mounted. It is disclosed as a means. Note that, as shown in FIG. 7, the gap formed when the thickness of the solder ball 15 used as the mounting means is larger than the thickness of the optical waveguide 18 is filled with underfill or the like.

The opto-electronic hybrid substrate in the second embodiment of the reference example is provided with an electric wiring layer, similarly to the opto-electronic hybrid substrate in the first embodiment of the present invention. And most of the electrical wiring layers are formed in the printed wiring board in the substrate 1 (not shown). The exposed portion of the electric wiring layer is formed on the other main surface and is connected to mounting means such as solder. Thereby, the opto-electric hybrid board and the second optical transmission board can be electrically connected.

The optical module according to the second aspect of the reference example is further provided with an optical semiconductor element such as a light emitting element or a light receiving element with respect to the opto-electronic hybrid substrate, similarly to the optical module according to the first aspect of the present invention. Is. In the optical transmission path in the first aspect, the optical waveguide and the optical path changer were mounted on the same substrate as the light emitting element and the light receiving element, but the optical transmission path and optical path in the second aspect of the present invention The converter is not limited thereto, and the optical transmission path and the optical path converter may be provided on the second optical transmission board.

  Other descriptions are the same as those of the optical module according to the first aspect of the present invention.

The photoelectric circuit system according to the second aspect of the reference example was mounted on the exposed portion of the electrical wiring layer on one main surface of the optical module, similarly to the photoelectric circuit system according to the first aspect of the present invention. And a semiconductor integrated circuit element. Similar to the optoelectric circuit system according to the first aspect of the present invention, the optical transmission path may transfer two sets of light in different directions, and dissipates heat generated by the semiconductor integrated circuit element. It may further comprise a cooling device.

[Optical Transmission Board in Third Aspect]
The optical transmission board, the opto-electronic hybrid board, and the optical module according to the third aspect of the present invention are indispensable in that a concave portion is formed on the other main surface side, and an optical waveguide 5 is formed in the concave portion. Except for certain points, the optical transmission board, the opto-electronic hybrid board, and the optical module according to the first aspect of the present invention are the same (see FIG. 8). Also, the effect obtained is to shorten the light transmission direction between the main surfaces, and since it is the same as the light transmission substrate, the opto-electronic hybrid substrate, and the optical module of the first aspect of the present invention, description thereof is omitted. To do.

  Hereinafter, the specific manufacturing process of the optical module of FIG. 4 will be described in detail based on the examples. However, the present invention is not limited to these examples, and the scope of the present invention is not deviated. Various changes can be made.

<The manufacturing process of the board | substrate 1 which has the 1st recessed part 2b and the 2nd recessed part 3b>
First, a multilayer wiring board having a thickness of 0.7 mm is manufactured. This multilayer wiring board is obtained by laminating seven substrates having a thickness of 0.1 mm. In addition, the board | substrate with a thickness of 0.1 mm mentioned above was produced by overlapping and heating-pressing an electric wiring layer and an insulating layer (epoxy resin).

  Of the above-described substrates having a thickness of 0.1 mm, those requiring die cutting were die-cut at necessary locations before they were laminated. Here, the location that needs to be punched refers to a location that becomes the first recesses 2b1 and 2b2 and the second recess 3b after lamination. The first recesses 2b1 and 2b2 were punched by three layers (0.3 mm), and the second recess 3b was punched by two layers (0.2 mm).

  After performing die cutting, seven layers of the above-mentioned substrate having a thickness of 0.1 mm are laminated, and further, by performing the same process as the conventional printed wiring board production process (for example, perforation process, plating process), The substrate 1 having the first recesses 2b1 and 2b2 and the second recess 3b was produced. In the substrate 1, the exposed portion 7a1 of the electric wiring layer is exposed on one main surface 2a1, and the exposed portion 7a2 of the electric wiring layer is exposed on one main surface 2a2. Further, the exposed portion 7b1 of the electric wiring layer is exposed on the bottom surface of the first recess 2b1, and the exposed portion 7b2 of the electric wiring layer is exposed on the bottom surface of the first recess 2b2. The exposed portion 7a1 is electrically joined to the exposed portion 7b1, and the exposed portion 7a2 is electrically joined to the exposed portion 7b2. Note that the electric wiring layer is also exposed on the other main surface 3a1 and the other main surface 3a2 (not shown). A solder resist layer is formed on the outermost surface.

  The substrate 1 having two first concave portions 2b and one second concave portion 3b was manufactured by the above process. In addition, in the board | substrate 1, the thickness of the location of the board | substrate 1 pinched | interposed between the 1st recessed part 2b and the 2nd recessed part 3b is 0.2 mm.

<Process for producing optical transmission holes 4a and 4b>
Using a drill, an optical transmission hole 4a having a diameter of 90 μm from the bottom surface of the first recess 2b1 to the bottom surface of the second recess 3b and from the bottom surface of the first recess 2b2 to the bottom surface of the second recess 3b, respectively. 4 were prepared at a pitch of 250 μm. Note that the number of light transmission holes 4a, the diameter, and the length of the pitch are the VCSELs (the emission diameter is 15 μm and the interval between the emission parts is 250 μm pitch) mounted in the recesses of the first recesses 2b1 in the process described later. A certain 4-channel array) and a PD (4-channel array having a light receiving diameter of 65 μm and an interval between light emitting parts of 250 μm pitch) provided in the recess of the second recess 3b.

<Filling process of transparent resin into optical transmission holes 4a and 4b>
In the same manner as the insulating layer, epoxy resin was filled in the light transmission holes 4a and 4b, and the transparent resins 14a and 14b were filled by curing the epoxy resin by irradiating with ultraviolet rays and baking.

<Process for producing optical waveguide 5>
(Lower cladding)
An epoxy resin was applied to the entire bottom surface of the second recess 3b by spin coating and prebaked. Next, in the second recess 3b, a photomask in which a Cr film was etched in accordance with the pattern of the lower clad part was used to expose a portion to be left. At that time, the alignment between the photomask and the substrate was performed using an alignment marker. The alignment marker can be prepared by a solder resist pattern, a metal pattern, an optical transmission hole, or the like when the substrate is formed.

  And after removing the unexposed part by development, the lower clad part 6b was formed by performing post-baking. Note that the thickness of the lower clad portion was 25 μm.

(Core part)
A material having a relative refractive index difference Δn = 1.4% with respect to the lower clad portion was applied to the lower clad portion by spin coating and prebaked. Using a photomask in which the Cr film was etched in accordance with the pattern of the lower clad portion, exposure was performed on the portion to be left. The alignment between the photomask and the substrate was performed accurately from the core pattern that is transparent on the photomask by performing mask alignment while confirming the light transmission hole 4 through the lower clad portion. .

  And after removing the unexposed part by development, the core part was formed by performing post-baking. The core portion had a thickness of 50 μm.

(Upper clad part)
The upper clad part was produced on the core part similarly to the production process of the lower clad part. The thickness was 25 μm as in the lower clad portion.

  The optical waveguide 5 was produced by performing the above process.

<Formation process of optical path changer>
The surface of the optical waveguide 5 corresponding to the opening positions of the light transmission holes 4a and 4b in the middle of the optical waveguide 5 is processed by a dicing saw so that the cross section becomes V-shaped, and the optical path changer 61 and 62 was produced. The depth of the cross section is assumed to reach about 80 μm from the surface of the optical waveguide 5 to the lower clad portion. As the dicing saw, a blade with a tip processed to 90 degrees and a thickness of 200 μm was used.

  The opto-electronic hybrid substrate was fabricated through the above steps.

<Installation of light emitting element and light receiving element>
The light emitting element 8 was mounted on the light transmission hole 4 of the first recess 2b so that the light emitting part faces the opening of the light transmission hole 4 with respect to the opto-electronic hybrid board. Similarly, the light receiving element 8 was mounted on the light transmission hole 4 of the first recess 2b so that the light receiving part faces the opening of the light transmission hole 4. Further, the light receiving element 9 was mounted on the light transmission hole 4 of the first recess 2b so that the light receiving portion and the opening face each other.

  By performing the above steps, the optical module of FIG. 4 could be easily manufactured.

FIG. 1 is a cross-sectional view schematically showing an example of an embodiment of an optical transmission board according to the first aspect of the present invention. FIG. 2 is a sectional view schematically showing an example of the embodiment of the optical transmission board according to the first aspect of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the embodiment of the opto-electronic hybrid substrate including the optical transmission substrate of FIG. FIG. 4 is a diagram schematically illustrating an example of an embodiment of an optical module including the opto-electronic hybrid substrate of FIG. FIG. 5 is a diagram schematically illustrating an example of an embodiment of an optoelectric circuit system including the optical module of FIG. FIG. 6 is a diagram schematically showing an example of an embodiment of an opto-electric circuit system in which a heat sink is further provided to the opto-electric circuit system of FIG. FIG. 7 is a cross-sectional view schematically showing an example of the embodiment of the optical transmission board according to the second aspect of the reference example . FIG. 8 is a sectional view schematically showing an example of the embodiment of the optical transmission board according to the third aspect of the present invention.

Explanation of symbols

1, 21, 31 Substrate 2a, 22a, 32a One main surface 2b, 22b, 32b A concave portion (first concave portion) provided on one main surface side
3a, 23a, 33a The other main surface 3b, 23b, 33b The recessed part (2nd recessed part) provided in the other main surface side
4, 24, 34 Optical transmission holes 5, 18, 35 Optical waveguide 6, 19, 36 Optical path converter 7 Exposed portion 8 of electric wiring layer Light emitting element 9 Light receiving element 10 VCSEL driver 11 TIA
12 CPU
13 GPU
14 heat sink 15 solder ball 16 underfill 17 second optical transmission board

Claims (9)

A concave portion provided on one main surface side for housing and providing an optical semiconductor element, a second concave portion provided on the other main surface side, and from a bottom surface of the concave portion to a bottom surface of the second concave portion A light transmission hole that opens between the bottom surface of the recess and the bottom surface of the second recess,
An optical waveguide that is entirely accommodated in the second recess, and that is thinner than the depth of the second recess ;
An optical path changer optically coupled to both the optical transmission hole and the optical waveguide to change the optical transmission direction between the optical transmission hole and the optical waveguide;
An optical transmission board comprising: The optical transmission board according to claim 1, wherein a transparent resin capable of transmitting light is provided in the optical transmission hole. The optical transmission board according to claim 1 or 2 ,
An electrical wiring layer comprising an exposed portion at least partially exposed on the bottom surface of the recess and the one main surface;
An opto-electronic hybrid board comprising: The opto-electronic hybrid board according to claim 3 , wherein the electrical wiring layer further includes an exposed portion at least partially exposed on the other main surface. The optoelectronic hybrid substrate according to claim 3 or 4 ,
In the recess, an optical semiconductor element mounted on the exposed portion of the electrical wiring layer and optically coupled to the light transmission hole;
An optical module comprising: The substrate has two sets of the recess and the light transmission hole,
The optical semiconductor element is a light emitting element and a light receiving element, and is mounted in each of the two sets of recesses,
There are two sets of optical path changers, one through one end of the optical waveguide and the light emitting element, and the other through the two sets of optical transmission holes, the other end of the optical waveguide and the light receiving element, respectively. the optical module according to 請 Motomeko 5 that have a light transmission path are optically coupled Te. The optical module according to claim 5 or 6 ,
A semiconductor integrated circuit element mounted on an exposed portion of the electrical wiring layer on the one main surface;
A photoelectric circuit system comprising: The semiconductor integrated circuit element is of two types, and is configured to transfer data between the two.
The substrate, the optical transmission path is further comprising another set, perform the data transfer by the two sets of the optical transmission path to transfer different directions of light from each other, in claim 7 according to claim 6 The optoelectric circuit system described. Wherein A a semiconductor integrated circuit device, and the light is provided so as to cover the semiconductor element, a light according to claim 7 or 8 further comprising a cooling device for dissipating heat generated by said semiconductor integrated circuit device Electrical circuit system.

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