JP2008158388A - Opto-electrical circuit board, optical module, and opto-electrical circuit system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an opto-electrical circuit substrate capable of making an accurate alignment between optical transmission substrates, and propagating an optical signal highly efficiently between the optical transmission substrates. <P>SOLUTION: The opto-electrical circuit substrate includes a first optical transmission substrate having a first electric wiring layer 6, a first transparent insulation layer 15, and an optical transmission hole 9; a second optical transmission substrate on which the first optical transmission substrate is mounted in such a way that a first principal surface 3 is opposed to a third principal surface 5, having a second electrical wiring layer 7, an optical waveguide 10, and a light path conversion part 11; and a mounting means 14 that is interposed in between the first electrical wiring layer 6 and the second electrical wiring layer 7, and is connected with them electrically. An optical module comprising the opto-electrical circuit substrate, and an opto-electrical circuit system with the optical module are also included. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optoelectric circuit board composed of a plurality of optical transmission boards, an optical module composed of the optoelectric circuit board, and an optoelectric circuit system composed of the optical module.

  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 optical semiconductor elements are converted to optical signals, and the optical signals are further converted into optical signals. An optical transmission technique that is transmitted by an optical wiring such as an optical waveguide formed on a mounting substrate has been studied.

For example, Patent Document 1 discloses a three-dimensional optical transmission technique. According to this, one substrate is provided with an optical waveguide, and the other substrate is provided with an optical semiconductor element such as a surface-emitting vertical cavity type light emitting laser (VCSEL). And it mounts by mounting means, such as solder, Furthermore, those board | substrates are electrically connected by aligning by the soldering resist layer provided in the circumference | surroundings of solder.
JP 2002-296435 A

  However, in the alignment using the solder resist layer as disclosed in Patent Document 1, even if electrical bonding between the substrates is possible, the light incident position and the light emitting position on one and the other substrates Therefore, the accuracy required for optical coupling cannot be satisfied, and the optical coupling between the two substrates has not been sufficiently achieved.

  Further, in the photoelectric circuit board disclosed in Patent Document 1, the distance from the light emission position on one optical transmission board to the light incidence position on the other optical transmission board is long, and light propagation loss is likely to occur. Was insufficient.

  The present invention has been devised to solve the problems in the conventional technology as described above, and the object thereof is to enable accurate alignment between optical transmission boards that realize high-precision optical coupling. Furthermore, it is another object of the present invention to provide an opto-electric circuit board capable of efficiently transmitting an optical signal between optical transmission boards.

  The present invention covers a first substrate having a first main surface and a second main surface, a first electric wiring layer provided on the first main surface side, and the first electric wiring layer. A first transparent insulating layer provided on the first main surface side, the first electric wiring layer having a first recess exposed at the bottom, and penetrating between both main surfaces, the second main surface And a first light transmission substrate having an opening on each surface of the first transparent insulating layer, and a second substrate having a third main surface facing the first main surface, , An optical path provided on the third main surface side, for converting the light transmission direction between the second electric wiring layer, the optical waveguide, and the optical transmission hole of the first optical transmission substrate and the optical waveguide. A second optical transmission board comprising a conversion unit, and the first optical wiring layer interposed between the first electric wiring layer and the second electric wiring layer. To implement the substrate feeding, an optical electric circuit board comprising a mounting means connected these electrically, a.

  The second optical transmission board is provided on the third main surface side so as to cover the second electric wiring layer, and a second transparent insulation having a second recess with the second electric wiring layer exposed at the bottom. It is preferable that a layer is further provided, and the optical path conversion unit is disposed on the second transparent insulating layer.

  It is preferable that a transparent resin having a higher refractive index than the first transparent insulating layer and capable of transmitting light is provided in the light transmission hole.

  Further, the present invention provides an electrical circuit for the photoelectric circuit board and the third electrical wiring layer, further comprising a third electrical wiring layer exposed on the second main surface of the first optical transmission board. And an optical semiconductor device that is optically coupled to the optical transmission hole.

  The present invention also relates to an optoelectric circuit system comprising the optical module and a semiconductor integrated circuit element mounted on the third electrical wiring layer and transferring signals to and from the optical semiconductor element.

  The photoelectric circuit board of the present invention includes a first substrate having a first main surface and a second main surface, a first electric wiring layer provided on the first main surface side, and the first electric circuit. A first transparent insulating layer provided on the first main surface side so as to cover the wiring layer, the first electric wiring layer having a first recess exposed at the bottom, and penetrating between both main surfaces; A first optical transmission board comprising a second main surface and optical transmission holes each having an opening on the surface of the first transparent insulating layer; and a third main surface opposite to the first main surface. Optical transmission between the second substrate having the second electrical wiring layer provided on the third main surface side, the optical waveguide, and the optical transmission hole and the optical waveguide of the first optical transmission substrate A second optical transmission board comprising an optical path changing unit for changing the direction; and the second optical transmission layer interposed between the first electric wiring layer and the second electric wiring layer. In order to mount the first optical transmission board on the board, the first optical transmission board and the second optical transmission board are accurately positioned by including mounting means electrically connected to these. Together, high-precision optical coupling is realized. Furthermore, since the light transmission hole is covered with the first transparent insulating layer, the light confinement effect in the light transmission hole is improved. Therefore, it is possible to achieve sufficiently high-efficiency optical signal propagation between the first optical transmission board and the second optical transmission board. In addition, by mounting so that the first transparent insulating layer and the optical waveguide are in contact with each other, it is possible to stably produce the height direction, so that it is possible to reduce the loss variation of the optical coupling portion, It is also possible to prevent foreign matters from entering the optical path.

  The second optical transmission board is provided on the third main surface side so as to cover the second electric wiring layer, and a second transparent insulation having a second recess with the second electric wiring layer exposed at the bottom. The optical path changing portion is disposed on the second transparent insulating layer, so that the distance between the optical waveguide and the opening of the optical transmission hole is reduced. Since the transmission distance of light from the opening on the surface to the optical path changing unit can be shortened, highly efficient propagation of an optical signal can be achieved.

  By providing a transparent resin having a higher refractive index than the first transparent insulating layer and capable of transmitting light in the light transmission hole, the light confinement effect in the transparent resin is improved.

  The photoelectric circuit system according to the present invention further includes a third electric wiring layer exposed on the second main surface of the first optical transmission board, and the photoelectric circuit board according to the above, An optical module comprising: an optical semiconductor element electrically mounted on the three electrical wiring layers and optically coupled to the optical transmission hole; and an optical module mounted on the exposed portion and transmitting signals between the optical semiconductor element A semiconductor integrated circuit element that performs transfer, and data transfer of the semiconductor integrated circuit element can be performed by optical transmission.

  Hereinafter, the optoelectric circuit board of the present invention will be described with reference to the drawings. However, the drawings are only examples of the embodiments, and the present invention is not limited to them.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of the photoelectric circuit board of the present invention. In FIG. 1, 1 is a first substrate, 2 is a second substrate, 3 is a first main surface, 4 is a second main surface, 5 is a third main surface, 6 is a first electrical wiring layer, and 7 is The second electrical wiring layer, 8 is the third electrical wiring layer, 9 is the light transmission hole, 10 is the optical waveguide, 11 is the optical path conversion unit, 12 is the solder resist layer, 13 is the transparent resin, 14 is the mounting means (in the figure) , Ball grid array), 15 is a first transparent insulating layer, 16 is a second transparent insulating layer, 22 is a first light transmission substrate, and 23 is a second light transmission substrate.

  In FIG. 1, the first optical transmission board 22 is used as a daughter board, and the second optical transmission board 23 is used as a mother board on which the first optical transmission board 22 is mounted. The daughter board here means a board that is mounted on the mother board to give the mother board a function. Since the daughter board requires a higher-speed electrical wiring design than the mother board, detailed design such as the dielectric constant of the material, the line width and the space width of the electrical wiring pattern is required.

  Each configuration will be described below.

<First optical transmission board>
The first substrate 1 has a first main surface 3 and a second main surface 4. As the first substrate 1, for example, a printed wiring board made of generally used epoxy resin or ceramic is used. Among them, since the mechanical strength is large and it is possible to effectively prevent warping of the substrate due to heat, a printed wiring board having a symmetric layer structure in which a resin insulating layer of the same thickness is formed on both sides is provided. Preferably, it is more preferable that the resin insulating layers on both sides have substantially the same thickness. The thickness of the substrate can be 0.4 to 1.5 mm.

  Moreover, since a complicated electrical wiring can be provided, a multilayer wiring board is preferably used as the first substrate 1. Here, the multilayer wiring board may be any one in which a plurality of electrical wiring layers and insulating layers are alternately laminated, for example, a board composed of a core substrate and a build-up layer formed on the wiring board surface side. 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.

  The first electrical wiring layer 6 is provided on the first main surface 3 side of the first substrate 1. Further, the first substrate 2 is also provided with a third electrical wiring layer 8 on the second main surface 4 side. The third electrical wiring layer 8 is connected to the first electrical wiring layer 6 and the electrical wiring. Electrically connected. Since the third electric wiring layer 8 is also formed on the second main surface 4 side in this way, an optical semiconductor element or the like is mounted on the third electric wiring layer 8 and electrically connected to the daughter. It can be mounted on another printed circuit board (motherboard) as a board. In addition, the 1st main surface 3 means the main surface which opposes the 2nd optical transmission board | substrate 23 side among the main surfaces in the 1st board | substrate 1. FIG. The second main surface 4 is a main surface on the back side with respect to the first main surface 3.

  The first electrical wiring layer 6 may be a conductive material, and for example, a metal such as Cu is used.

  The first electrical wiring layer 6 is produced, for example, by laminating a copper foil on the outermost surface of the first substrate 1, performing photolithography and etching.

  In the present invention, the first transparent insulating layer 15 is used as an alternative material for a general solder resist. The first transparent insulating layer 15 is provided on the first main surface 3 of the first substrate 1 so as to cover the first electric wiring layer 6.

  Unlike the solder resist which is generally colored, the first transparent insulating layer 15 is transparent. Therefore, in the formation process of the 1st recessed part 17 after coat | covering the 1st transparent insulating layer 15 to the 1st electrical wiring layer 6, the position of the 1st electrical wiring layer 6 can also be confirmed from on the 1st transparent insulating layer 15. Therefore, the first recess 17 can be produced at a desired accurate position.

  The first transparent insulating layer 15 has a first recess 17. Here, the first concave portion 17 has a shape in which the first electric wiring layer 6 is exposed on the bottom surface of the concave portion. According to this configuration, the mounting means 14 such as solder is filled in the first concave portion 17 so that a part of the mounting means 14 is fitted into the first concave portion without a gap. Therefore, the connection between the first transparent insulating layer 15 and the mounting means 14 can be strengthened, and the second electrical wiring layer 7 and the mounting means 14 can be electrically joined. In addition, the 1st recessed part 17 is produced by carrying out mask exposure using the light transmission hole 9 mentioned later as a marker (reference | standard), and developing an unexposed part after baking. By doing in this way, the mounting means position can be provided accurately with reference to the optical transmission hole 9, and the mounting accuracy is improved.

  Moreover, the thickness of the 1st transparent insulating layer 15 is larger than the thickness of a general solder resist, and is specifically 50 micrometers or more. By having a thickness of 50 μm or more, the distance between the optical path conversion unit 11 and the opening of the light transmission hole 9 on the surface of the first transparent insulating layer 15 is shortened, and the effect of reducing the light propagation loss is obtained. Obtainable.

  Specifically, the first transparent insulating layer 15 is a so-called permanent resist. Here, the permanent resist is an electroless plating that is performed for a long time under solvent resistance, high temperature, and high alkalinity conditions such as isopropyl alcohol, trichloroethylene, methylene chloride, acetone, etc., despite high resolution and easy development. It is a resist that has excellent resistance to plating solution, and also has heat resistance that can withstand temperatures around 260 ° C. in the soldering process. The permanent resist is produced, for example, by irradiating the epoxy acrylate resin with ultraviolet light. The permanent resist in the present invention is preferably a permanent resist resin having a kinematic viscosity of 2000 cst in order to form the first transparent insulating layer 15 having a thickness of 50 to 400 μm. And after apply | coating this on the 1st board | substrate 1 and carrying out spin coating, a 1st transparent insulating layer can be provided on the 1st board | substrate 1 by performing exposure and image development. In addition, as a method for increasing the thickness of the first transparent insulating layer 15, a method of increasing the kinematic viscosity, a thick film coating apparatus (for example, a doctor blade) is used, or the rotation speed of the spin coater For example.

  The first substrate 1 and the first transparent insulating layer 15 are provided with light transmission holes 9 from the second main surface 4 to the first transparent insulating layer 15. In FIG. 1, the light transmission hole 9 is perpendicular to the second main surface 4 of the first substrate 1 and extends from the second main surface 4 to the first transparent insulating layer 15 in the first substrate 1. The through-holes that transmit light by penetrating through the respective openings of the second main surface 4 and the surface of the first transparent insulating layer 15 are shown. Here, the surface of the first transparent insulating layer 15 refers to a surface facing the second optical transmission substrate 23.

  For example, when an optical semiconductor element such as a light emitting element is installed in the opening of the light transmission hole 9 in the second main surface 4, the light emitted from the light emitting element propagates through the light transmission hole 9 to Light is transmitted to the main surface.

  The light transmission hole 9 includes a first light transmission hole 9 a provided in the first substrate 1 and a second light transmission hole 9 b provided in the first transparent insulating layer 15.

  For the formation of the first light transmission hole 9a, a drill or a laser used in a normal printed circuit board drilling process is preferably used. And the 1st optical transmission hole 9a is formed by letting the 1st board | substrate 1 penetrate from one main surface to the other main surface.

  The second light transmission hole 9b is produced so as to have the same hole diameter as that of the first light transmission hole 9a. As a method for producing the second light transmission hole 9b, after the production of the first light transmission hole 9a, a method of drilling with a drill or a laser, or mask exposure using the light transmission hole 9 as a marker (reference) and unexposed after baking. And a method of developing the part. In particular, the second light transmission hole 9b can be manufactured in a single process with the first concave portion 17 being manufactured. Therefore, the light transmission hole 9 is used as a marker (reference) for mask exposure, and after baking, A method of developing the exposed area is preferred.

  It is preferable that a transparent resin 13 capable of transmitting light is provided in the light transmission hole 9. By doing so, light reflection at the opening of the light transmission hole 9 can be reduced, and light scattering at the optical path changing unit 11 can be further reduced.

  When the transparent resin 13 is provided in the light transmission hole 9, the refractive index of the transparent resin 13 is preferably higher than the refractive index of the first transparent insulating layer 15. Thereby, the first transparent insulating layer 15 functions as a cladding part, and the transparent resin 13 in the light transmission hole 9 functions as a core part, so that an optical signal can be sufficiently confined in the transparent resin 13.

  Examples of the transparent resin 13 include polysilane that causes a photobleaching phenomenon in which the refractive index decreases when irradiated with light, or a photosensitive acrylic resin or epoxy resin that can be removed by developing the irradiated portion.

  When using an ultraviolet curable acrylic resin or epoxy resin, the light transmission hole 9 is filled with these photosensitive polymer materials, heated and cured, and then a photomask (having a diameter smaller than that of the light transmission hole 9). A portion (light) removed by development in the light transmission hole 9 after removing the resin of the ultraviolet light irradiation portion by performing development by irradiating with ultraviolet light through a circular pattern light transmitting portion) The center of the transmission hole) is filled with a material having a higher refractive index than that of the material initially filled, and is cured by irradiating with ultraviolet light without using a photomask. A refractive index distribution is formed in the transparent resin 13. Also, a hole or hole is drilled in the center of the light transmission hole once filled with a transparent resin, and a transparent resin having a higher refractive index is filled inside to form a refractive index distribution inside the light transmission hole 9. You can also At that time, the size of the second light transmission hole 9b in the first transparent insulating layer 15 is preferably set to a size matched to the diameter of the central portion of the first light transmission hole 9a.

  The hole diameter of the light transmission hole 9 is determined based on the light receiving / emitting diameters of the light emitting element and the light receiving element and the size of the optical path changing unit 11 described later, and further considering the spread of light. The hole diameter of the light transmission hole 9 optically coupled to the light receiving element is smaller than the light receiving diameter of the light receiving element, and the hole diameter of the light transmission hole 9 optically coupled to the light emitting element is larger than the light emitting diameter of the light emitting element. Large is preferred. For example, when using a VCSEL having a diameter of 15 μm and a pitch of 250 μm and a 4-channel array, the light transmission holes 9 have a diameter of 15 μm or more and a pitch of 250 μm to form the light transmission holes 9 for each light emitting part. In addition, when using a 4-channel array PD having a diameter of 65 μm and a pitch of 250 μm, the light transmission holes 9 may be formed with a diameter of 65 μm or less and a pitch of 250 μm. preferable.

<Second optical transmission board>
The second light transmission substrate 23 has the third main surface 5 of the second substrate 2, and the first light so that the first main surface 3 and the third main surface 5 of the first substrate 1 face each other. This means that the transmission board 22 is mounted.

  The material of the second substrate 2, the thickness of the substrate, the mounting structure, and the like are not particularly limited, and may be the same as the first substrate 1 described above, for example.

  The second electrical wiring layer 7 is provided on the third main surface 5 side of the second substrate 2. And thereby, the 1st optical transmission board | substrate 22 can be mounted with respect to the 2nd electrical wiring layer 7 using a mounting means.

  In addition, the 3rd main surface 5 means the main surface which opposes the 1st optical transmission board | substrate 22 side among the main surfaces in the 2nd board | substrate 2. As shown in FIG.

  The optical waveguide 10 is provided on the third main surface 5 side of the second substrate 2. Here, the optical waveguide 10 plays a role of transmitting light in a direction perpendicular to the thickness direction of the second substrate 2.

  As shown in FIG. 1, the optical waveguide 10 is preferably composed of a core portion (a shaded portion in the optical waveguide 10 in FIG. 1) and a cladding portion that surrounds the core portion and has a refractive index smaller than that of the core portion. By adjusting the refractive indexes of the core part and the clad part, good light propagation is possible.

  Examples of a method for manufacturing the optical waveguide 10 having the core portion include a direct exposure method, a refractive index change method (photo bleaching method), and a reactive ion etching method.

  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, in the case of using a negative photosensitive epoxy resin, by applying a material, preparing a photomask that exposes a necessary portion and exposing and baking, the exposed portion of the resin is cured, The unexposed portion of the resin is removed by development to obtain a desired pattern. By applying this method to both the lower clad part and the upper clad part and the core part, the optical waveguide 10 can be formed only at a necessary place in the entire substrate. 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 10 having a thickness of about 100 μm can be obtained as about 25 μm, which is half of the portion.

  When the first optical transmission board 22 is mounted on the second optical transmission board 23, the optical path conversion unit 11 is optically coupled to both the optical transmission hole 9 and the optical waveguide 10 of the first optical transmission board 22. And has a function of changing the light transmission direction between the light transmission hole 9 and the optical waveguide 10. Specifically, the light path conversion unit 11 is a light reflecting surface having a certain inclination angle (for example, 45 ° with respect to the third main surface 5), thereby converting the incident direction of light to a substantially right angle. Thus, the optical transmission hole 9 and the optical waveguide 10 having different optical path directions can be optically coupled.

  In FIG. 1, the optical path conversion unit 11 is formed at a location corresponding to the position of the opening of the optical transmission hole 9 that the surface of the first transparent insulating layer 15 has, and the optical path conversion unit 11 is provided after the optical waveguide 10 is formed. . Here, the “location corresponding to the opening position of the optical transmission hole 9” means that the first optical transmission substrate 22 is most between the optical transmission hole 9 and the optical waveguide 10 when mounted on the second optical transmission substrate 23. An installation location of the optical path conversion unit 11 that enables high-efficiency optical coupling.

  As a method of forming the optical path changing portion 11, generally, a part of the optical waveguide is cut obliquely by grooving with a dicing saw using a diamond blade whose tip is processed at 45 degrees or 90 degrees. It is formed. In addition, there are a method of forming a slope by patterning the optical waveguide 10 using a gray mask, oblique exposure, or the like, or a method of using a marking machine used when cutting a printed circuit board.

  In FIG. 1, a configuration in which the optical path conversion unit 11 is formed in the optical waveguide 10 is given as a specific example. However, the optical path conversion unit 11 in the present invention is not limited thereto, and for example, a configuration different from the optical waveguide 10 It may be.

  The optical path conversion unit 11 may be formed on the middle surface of the optical waveguide 10, or may be gold (Au), silver (Ag), platinum (Pt), aluminum (Al), copper (Cu), or the like. Alternatively, a film having a high reflectance with respect to the light guided through the optical waveguide 10 may be formed on the surface by a thin film process technique such as a vapor deposition method.

  The second optical transmission board 23 preferably further includes a second transparent insulating layer 16 so as to cover the second electric wiring layer 7.

  In the present invention, like the first transparent insulating layer 15, the second transparent insulating layer 16 is also used as an alternative material for a general solder resist.

  The second transparent insulating layer 16 has a second recess 18. Here, the second recess 18 has a shape in which the second electrical wiring layer 7 is exposed on the bottom surface of the recess. According to this configuration, the second electrical wiring layer 7 and the mounting means can be electrically joined by filling the second recess 18 with mounting means such as solder.

  Moreover, since the thickness and raw material of the 2nd transparent insulating layer 16 are the same as that of the 1st transparent insulating layer mentioned above, those description is abbreviate | omitted.

  When the second optical transmission substrate 23 includes the second transparent insulating layer 16, the optical path conversion unit 11 is preferably disposed on the second transparent insulating layer 16. As a result, the distance between the optical waveguide 10 and the opening of the light transmission hole 9 approaches, and the light transmission distance from the opening on the surface of the first transparent insulating layer 15 to the optical path conversion unit 11 can be shortened. Highly efficient propagation of optical signals can be achieved.

<Mounting method>
The first optical transmission board 22 is mounted on the second optical transmission board 23 on the main surface 3 side of the first optical transmission board 22, that is, on the main surface side mounted on the second optical transmission board 23. Mounting means 14 is provided. As the mounting means 14, for example, those formed of a metal such as Cu, Ni, Ag, W, Mo, Al, and Au are used. Similar electrodes are provided as mounting means at positions corresponding to the third main surface 5 of the second optical transmission board 23, and the first optical transmission board 22 is connected to the second optical transmission board 23 via solder or the like. Implemented.

  Specific examples of the mounting means 14 include BGA (Ball Grid Array), PGA (Pin Grid Array), and LGA (Land Grid Array).

  The mounting means 14 is filled in the first recess 17 and is electrically connected to the first electrical wiring layer 6, and is further filled in the second recess 18 and electrically connected to the second electrical wiring layer 7. Connected.

  A procedure for manufacturing the photoelectric circuit board (FIG. 1) of the present invention will be described below with reference to FIGS.

  First, an epoxy resin is formed on the first main surface 3 of the first substrate 1 (FIG. 2A) in which the first electric wiring layer 6, the third electric wiring layer 8, and the first optical transmission hole 9a are already provided. A first transparent insulating layer 15 such as is prepared. Thereafter, mask exposure is performed using the light transmission hole 9 as a marker (reference), and an unexposed portion is developed after baking, whereby the second light transmission hole 9b and the first light transmission hole 9b are positioned at desired positions with respect to the first transparent insulating layer 15. The concave portion 17 is formed (FIG. 2B).

  Then, the optical transmission hole 9 is filled with a transparent resin 13 such as an epoxy resin (FIG. 2C), and solder balls are provided in the first recess 17 as mounting means (FIG. 2D). .

  Further, a second transparent insulating layer 16 such as an epoxy resin is formed on the third main surface 5 of the second substrate 2 (FIG. 3A) on which the second electric wiring layer 7 has already been provided (FIG. 3 ( b)) After that, the second recess 18 is formed by exposure and development (FIG. 3C).

  Then, the second concave portion 18 is used as a marker (reference), and the optical waveguide 10 and the optical path conversion unit 11 are provided at desired positions (FIG. 3D).

  Finally, after the solder ball provided in the first recess 17 of the first optical transmission board 22 shown in FIG. 2D is temporarily installed so as to fit into the second recess 18 of the second optical transmission board 23, 1 can be produced by mounting the first optical transmission board 22 on the second optical transmission board 23 with the solder balls while melting the solder balls and performing self-alignment in the reflow furnace. it can.

  The light obtained by mounting the first optical transmission board 22 against the second optical transmission board 23 while being pressed so that the distance between the surface of the first transparent insulating layer 15 and the optical waveguide 11 approaches. Variations in the loss of the optical coupling portion in the circuit board can be suppressed, and contamination of foreign matters between the first transparent insulating layer 15 and the optical waveguide 11 can be prevented.

  Thus, (1) the step of forming the first recess 17 at the position of the first electrical wiring layer 6 with the light transmission hole 9 as a reference, and (2) the light transmission hole with the second recess 18 as a reference. Performing the step of aligning the optical path changer 11 at a position where it can be optically coupled to 9, and the step of (3) mounting the first optical transmission board 22 and the second optical transmission board 23 by self-alignment. Thus, the photoelectric circuit board of the present invention is manufactured.

<Optical Module and Photoelectric Circuit System of the Present Invention>
The optical module of the present invention is provided with the third electrical wiring layer 8 exposed on the second main surface 4, and further mounted with an optical semiconductor element 19 electrically mounted on the third electrical wiring layer 8. Say things. The optical semiconductor element 19 is optically coupled to the optical transmission hole 9 and can further propagate an optical signal to and from the optical waveguide 10 via the optical path changer 11. Here, examples of the optical semiconductor element 19 include a light emitting element and a light receiving element.

  For example, in FIG. 4, when a light emitting element is mounted as the optical semiconductor element 19, an optical signal emitted from the light emitting point propagates through the optical transmission hole 9, is reflected by the optical path conversion unit 11, and the optical path is approximately 90 degrees. It is converted and reaches the end of the optical waveguide 10.

  In addition to the embodiment of FIG. 4, the optical module of the present invention includes two first optical transmission boards 22 each including an optical semiconductor element 19 electrically mounted on a third electrical wiring layer, one second light. It may be mounted on the transmission board 23, and one of the optical semiconductor elements may be a light emitting element and one of the optical semiconductor elements is a light receiving element, and the light emitting element and the light receiving element may be optically coupled. In this case, as a configuration, optical path changers are provided at both ends of the optical waveguide so that the optical waveguide, the light emitting element, and the light receiving element are all optically coupled, and the optical path is converted by approximately 90 degrees.

  As shown in FIG. 4, the optoelectric circuit system of the present invention is a system in which a semiconductor integrated circuit 21 is further mounted on an optical module. Here, examples of the semiconductor integrated circuit 21 include a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and the like.

  The optoelectric circuit system of the present invention can transfer data for converting an electrical signal from a semiconductor integrated circuit element into light in the optical semiconductor element by optical transmission.

  In the optoelectric circuit system according to the present invention, since the semiconductor integrated circuit element 21 is provided on the second main surface 4 side, which is the same as the optical semiconductor element 19, and the distance between them is short, information consisting of an electrical signal and an optical signal is provided. The transmission path can be further shortened.

FIG. 1 is a sectional view schematically showing an example of an embodiment of the photoelectric circuit board of the present invention. 2A to 2D are cross-sectional views schematically showing an example of a method for manufacturing the first optical transmission board before mounting on the second optical transmission board. 3A to 3D are cross-sectional views schematically showing an example of a method for manufacturing the second optical transmission board before mounting the first optical transmission board. FIG. 4 is a sectional view schematically showing an example of the embodiment of the photoelectric circuit system of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 2nd board | substrate 3 1st main surface 4 2nd main surface,
5 Third main surface,
6 First Electric Wiring Layer 7 Second Electric Wiring Layer 8 Third Electric Wiring Layer 9 Optical Transmission Hole 9a First Optical Transmission Hole 9b Second Optical Transmission Hole 10 Optical Waveguide 11 Optical Path Conversion Unit 12 Solder Resist Layer 13 Transparent Resin 14 Mounting Means 15 First transparent insulating layer 16 Second transparent insulating layer 17 First recess 18 Second recess 19 Optical semiconductor element (light emitting element)
20 VCSEL driver 21 Semiconductor integrated circuit element (CPU)
22 First optical transmission board 23 Second optical transmission board

Claims (5)

A first substrate having a first main surface and a second main surface, a first electric wiring layer provided on the first main surface side, and the first electric circuit layer so as to cover the first electric wiring layer A first transparent insulating layer having a first recess with the first electrical wiring layer exposed at the bottom, and penetrating between both main surfaces, the second main surface and the first A first optical transmission board comprising optical transmission holes each having an opening on the surface of the transparent insulating layer;
A second substrate having a third main surface facing the first main surface; a second electric wiring layer provided on the third main surface side; an optical waveguide; and the first optical transmission substrate. A second optical transmission board comprising: an optical path conversion unit that converts an optical transmission direction between the optical transmission hole and the optical waveguide;
A mounting means interposed between the first electric wiring layer and the second electric wiring layer and electrically connected to the second optical transmission board to mount the first optical transmission board on the second optical transmission board; ,
A photoelectric circuit board comprising: The second optical transmission board is
A second transparent insulating layer provided on the third main surface side so as to cover the second electric wiring layer, and having a second recess exposed at the bottom of the second electric wiring layer; The photoelectric circuit board according to claim 1, wherein the conversion portion is disposed on the second transparent insulating layer.   The photoelectric circuit board according to claim 1 or 2, wherein a transparent resin having a refractive index higher than that of the first transparent insulating layer and capable of transmitting light is provided in the light transmission hole. The photoelectric circuit board according to claim 1, further comprising a third electrical wiring layer exposed on the second main surface of the first optical transmission board,
An optical module comprising: an optical semiconductor element electrically mounted on the third electrical wiring layer and optically coupled to the optical transmission hole. An optical module according to claim 4,
And a semiconductor integrated circuit device mounted on the third electrical wiring layer and transferring signals to and from the optical semiconductor device.

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