Optical module and method for manufacturing the optical module

Abstract

To provide an optical module that can suppress the decline in yield. [Solution] The optical module (10) includes a wiring board (20), a plurality of electronic components (30) mounted on the wiring board (20), and a waveguide component (40) mounted on the wiring board (20) and interconnecting the plurality of electronic components (30). The waveguide component (40) includes a waveguide substrate (50) having an optical waveguide (52) and an upper surface and a lower surface, and an optical integrated circuit element (70) mounted on the lower surface of the waveguide substrate (50) and optically connected to the optical waveguide (52). The waveguide component (40) includes an electrical integrated circuit element (60) mounted on the upper surface of the waveguide substrate (50) and electrically connected to the optical integrated circuit element (70).

Description

[Technical Field]

[0001] The present invention relates to an optical module and a method for manufacturing the optical module. [Background technology]

[0002] Conventionally, optical modules used in optical communications have been known that include a wiring board, an optical waveguide stacked on the wiring board, an optical element mounted on the wiring board, and an electronic component mounted on the wiring board (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-018409 [Overview of the Initiative] [Problem to be solved by the invention]

[0004] However, if the number of components mounted on a wiring board increases, there is a risk that the yield of optical modules will decrease. [Means for solving the problem]

[0005] According to one aspect of the present invention, the present invention comprises a wiring board, a plurality of electronic components mounted on the wiring board, and a waveguide component mounted on the wiring board and connecting the plurality of electronic components to each other, wherein the waveguide component has an optical waveguide and comprises a waveguide board having a first surface and a second surface opposite to the first surface, an optical integrated circuit element mounted on the first surface of the waveguide board and optically connected to the optical waveguide, and an electrical integrated circuit element mounted on the second surface of the waveguide board and electrically connected to the optical integrated circuit element. [Effects of the Invention]

[0006] According to one aspect of the present invention, it has the effect of suppressing a decrease in yield. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view showing an optical module according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing the optical module of the first embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an enlarged portion of the optical module according to the first embodiment. [Figure 4] Figure 4 is a flowchart showing an example of the manufacturing process for the optical module of the first embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a method for manufacturing the optical module according to the first embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view showing a method for manufacturing an optical module according to the first embodiment. [Figure 7] Figure 7 is a schematic cross-sectional view showing a method for manufacturing an optical module according to the first embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing a method for manufacturing the optical module according to the first embodiment. [Figure 9] FIG. 9 is a schematic cross-sectional view showing a method for manufacturing the optical module according to the first embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a method for manufacturing the optical module according to the first embodiment. [Figure 11] FIG. 11 is a schematic cross-sectional view showing a method for manufacturing the optical module according to the first embodiment. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a method for manufacturing the optical module according to the first embodiment. [Figure 13] FIG. 13 is a schematic cross-sectional view showing the optical module according to the second embodiment. [Figure 14] Figure 14 is a schematic cross-sectional view showing an example of a modified optical module. [Figure 15] FIG. 15 is a schematic cross-sectional view showing an optical module according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] The embodiments will be described below with reference to the attached drawings. Note that, for convenience, the attached drawings may show enlarged versions of characteristic parts to make the features easier to understand, and the dimensional ratios of each component may differ between drawings. Furthermore, in the cross-sectional views, to make the cross-sectional structure of each member easier to understand, the hatching of some members has been replaced with a textured pattern, and the hatching of some members has been omitted.

[0009] (First embodiment) The first embodiment will be described below with reference to Figures 1 to 12. (Overall configuration of optical module 10) As shown in Figure 1, the optical module 10 includes a wiring board 20, one or more (six in this embodiment) electronic components 30 mounted on the wiring board 20, and waveguide components 40 mounted on the wiring board 20. The optical module 10 includes, for example, an optical fiber 90. As the electronic components 30, for example, an IC chip incorporating a digital signal processor, an amplifier, etc., can be used.

[0010] (Configuration of the wiring board 20) The wiring board 20 is formed, for example, in a flat plate shape. The wiring board 20 is formed, for example, in a rectangular shape in plan view. Waveguide components 40 and electronic components 30 are mounted on the wiring board 20. Other elements besides the waveguide components 40 and electronic components 30, such as optical functional elements, may also be mounted on the wiring board 20. Examples of optical functional elements include light-emitting elements, optical modulators, optical amplifiers, and optical attenuators.

[0011] 2 and 3, the wiring board 20 has a plurality of connection pads 21 provided on the upper surface of the wiring board 20 and a plurality of connection pads 22 provided on the upper surface of the wiring board 20. The connection pads 21 are pads that are electrically connected to the electronic component 30. The connection pads 22 are pads that are electrically connected to the waveguide component 40. Although not shown in the figures, the wiring board 20 has, for example, wiring that electrically connects the connection pads 21 and the connection pads 22.

[0012] (Configuration of electronic component 30) 3, each electronic component 30 has a plurality of electrode pads 31 formed on the bottom surface of the electronic component 30. Each electronic component 30 is mounted on the top surface of the wiring board 20. Each electronic component 30 is, for example, flip-chip mounted on a connection pad 21 of the wiring board 20. For example, the electrode pad 31 of each electronic component 30 is electrically connected to the connection pad 21 of the wiring board 20 via a solder layer 32. As a result, each electronic component 30 is electrically connected to the connection pad 21 via the electrode pad 31 and the solder layer 32. The plurality of electronic components 30 are connected to each other, for example, via wiring and a waveguide component 40 within the wiring board 20.

[0013] (Configuration of the waveguide component 40) 1, the waveguide component 40 includes a waveguide substrate 50 and one or more electrical integrated circuit (EIC) elements 60 mounted on the upper surface of the waveguide substrate 50. The waveguide component 40 includes one or more photonic integrated circuit (PIC) elements 70 mounted on the lower surface of the waveguide substrate 50. The waveguide component 40 of this embodiment includes six EIC elements 60 and six PIC elements 70. The waveguide component 40 includes, for example, one or more (two in this embodiment) support members 80 mounted on the waveguide substrate 50.

[0014] Each PIC element 70 has an optical circuit. The optical circuit includes, for example, optical elements and optical modulation circuits. Examples of optical elements include photodetectors such as photodiodes and avalanche photodiodes. Each EIC element 60 includes, for example, an electrical circuit that is electrically connected to the optical circuit of the PIC element 70 and a signal processing circuit that performs high-speed signal processing with the electronic component 30. The electrical circuit includes, for example, an electronic circuit such as a driver that drives the optical elements included in the optical circuit and an impedance conversion amplifier that converts the photocurrent generated in the optical circuit into a voltage signal. The signal processing circuit includes, for example, a digital-to-analog converter and an analog-to-digital converter. The amount of heat generated by each EIC element 60 is greater than the amount of heat generated by each PIC element 70. The thickness of each PIC element 70 is formed to be thicker than the thickness of each EIC element 60.

[0015] Waveguide component 40 interconnects multiple electronic components 30. Waveguide component 40 interconnects multiple electronic components 30, for example, through optical signals or electrical signals. (Configuration of waveguide substrate 50) As shown in Figure 3, the waveguide substrate 50 has a base material 51 and one or more optical waveguides 52 formed on the base material 51. The optical waveguides 52 are optically connected (optically connected) to, for example, a PIC element 70. The optical waveguides 52 have a cladding layer 53 and a core layer 54. For example, silicon optical waveguides or glass optical waveguides can be used as optical waveguides 52. In this embodiment, the optical waveguide 52 is a silicon optical waveguide.

[0016] The base material 51 is formed, for example, in the shape of a flat plate. The base material 51 is formed, for example, in the shape of a rectangle in plan view. As the material for the base material 51, for example, silicon (Si) or silicon nitride (SiN) can be used.

[0017] The cladding layer 53 is provided on the lower surface of the substrate 51. The cladding layer 53 is formed, for example, to cover the lower surface of the substrate 51. As the material for the cladding layer 53, for example, silicon oxide (SiO2) can be used.

[0018] The cladding layer 53 includes a first cladding layer 53A formed on the lower surface of the substrate 51 and a second cladding layer 53B formed on the lower surface of the first cladding layer 53A so as to cover the core layer 54. In each drawing, the first cladding layer 53A and the second cladding layer 53B are distinguished by solid lines to make them easier to understand. However, in an actual waveguide component 40, the boundary between the first cladding layer 53A and the second cladding layer 53B may disappear, and the boundary may not be clear.

[0019] The core layer 54 is for propagating an optical signal. The core layer 54 is formed so as to be embedded in the cladding layer 53. The entire outer periphery of the core layer 54 is surrounded by the cladding layer 53. The core layer 54 is formed on the lower surface of the first cladding layer 53A. The entire upper surface of the core layer 54 is covered by the first cladding layer 53A. The entire side and lower surfaces of the core layer 54 are covered by the second cladding layer 53B. The core layer 54 is formed, for example, parallel to the lower surface of the substrate 51. Here, in order to ensure that the propagation of the optical signal occurs only within the core layer 54, a material having a higher refractive index than the cladding layer 53 made of SiO2 is selected as the material for the core layer 54. For example, Si can be used as the material for the core layer 54. Light input to the core layer 54 propagates in a propagation direction corresponding to the planar shape of the core layer 54.

[0020] The waveguide component 40 has a plurality of through vias 55 that penetrate the waveguide substrate 50 in the thickness direction, a plurality of pads 56 provided on the upper surface of the waveguide substrate 50, and a plurality of pads 57, 58 provided on the lower surface of the waveguide substrate 50.

[0021] Each through via 55 is formed to penetrate the substrate 51 in the thickness direction and also penetrate the cladding layer 53 in the thickness direction. Each through via 55 is formed to penetrate the first cladding layer 53A in the thickness direction and also penetrate the second cladding layer 53B in the thickness direction. Each through via 55 is formed, for example, to fill a through hole that penetrates the waveguide substrate 50 in the thickness direction.

[0022] Each pad 56 is provided on the upper surface of the substrate 51. Each pad 56 is electrically connected to a through via 55. The pads 56 are pads that are electrically connected to the EIC element 60.

[0023] Each of the pads 57, 58 is provided on the lower surface of the second cladding layer 53B. Each of the pads 57, 58 is electrically connected to the pad 56 via a through via 55. Each of the pads 57 is electrically connected to the PIC element 70. Each of the pads 58 is electrically connected to the support member 80.

[0024] (Configuration of EIC element 60) Each EIC element 60 has a plurality of electrode pads 61 formed on its lower surface. Each EIC element 60 is mounted on the upper surface of the waveguide substrate 50. Each EIC element 60 is flip-chip mounted, for example, on a pad 56 of the waveguide substrate 50. For example, the electrode pads 61 of each EIC element 60 are electrically connected to the pads 56 of the waveguide substrate 50 via a solder layer 62. Thus, each EIC element 60 is electrically connected to the pads 56 via the electrode pads 61 and the solder layer 62.

[0025] (Configuration of PIC element 70) Each PIC element 70 has a plurality of electrode pads 71 ​​formed on its upper surface. Each PIC element 70 is mounted on the lower surface of the waveguide substrate 50. That is, each PIC element 70 is mounted on the lower surface of the waveguide substrate 50, opposite the upper surface on which the EIC element 60 is mounted. Each PIC element 70 is flip-chip mounted, for example, on a pad 57 of the waveguide substrate 50. For example, the electrode pad 71 of each PIC element 70 is electrically connected to the pad 57 of the waveguide substrate 50 via a solder layer 72. As a result, each PIC element 70 is electrically connected to the pad 57 via the electrode pad 71 and the solder layer 72. Furthermore, the electrode pad 71 of each PIC element 70 is electrically connected to the electrode pad 61 of each EIC element 60 via the solder layer 72, the pad 57, the through-via 55, the pad 56, and the solder layer 62. In this way, each PIC element 70 and each EIC element 60 are electrically connected to each other over a short distance by through vias 55 that penetrate the waveguide substrate 50 in the thickness direction. Furthermore, each PIC element 70 is arranged so as to overlap with each EIC element 60 in a plan view. This allows each PIC element 70 and each EIC element 60 to be connected to each other by a linear path along the thickness direction of the waveguide substrate 50.

[0026] (Configuration of support member 80) Each support member 80 includes a main body portion 81, a plurality of through vias 82 that penetrate the main body portion 81 in the thickness direction, a plurality of connecting pads 83 provided on the upper surface of the main body portion 81, and a plurality of connecting pads 84 provided on the lower surface of the main body portion 81.

[0027] The main body 81 is formed, for example, in the shape of a column extending in the vertical direction in the figure. The thickness of the main body 81 is formed to be thicker than the thickness of the PIC element 70. The main body 81 is, for example, a dielectric. As a material for the main body 81, for example, ceramics such as aluminum oxide (Al2O3) or aluminum nitride (AlN) can be used.

[0028] Each through via 82 is formed, for example, to fill a through hole that penetrates the main body 81 in the thickness direction. Each connection pad 83 is electrically connected to a through via 82. Each connection pad 83 is a pad that is electrically connected to the waveguide substrate 50. Specifically, each connection pad 83 is electrically connected to a pad 58 on the waveguide substrate 50. Each connection pad 84 is electrically connected to a connection pad 83 via a through via 82. Each connection pad 84 is a pad that is electrically connected to the wiring board 20. Specifically, each connection pad 84 is electrically connected to a connection pad 22 on the wiring board 20.

[0029] Each support member 80 is mounted on the lower surface of the waveguide substrate 50. That is, each support member 80 in this embodiment is mounted on the same lower surface of the waveguide substrate 50 on which the PIC element 70 is mounted. Each support member 80 is mounted on the lower surface of the waveguide substrate 50 by bonding a connection pad 83 to a pad 58 of the waveguide substrate 50. For example, the connection pad 83 of the support member 80 is electrically connected to the pad 58 of the waveguide substrate 50 via a solder layer 85. Thus, the support member 80 is electrically connected to the pad 58 via the connection pad 83 and the solder layer 85. Furthermore, the connection pad 83 of the support member 80 is electrically connected to the electrode pad 61 of each EIC element 60 via the solder layer 85, the pad 58, the through via 55, the pad 56, and the solder layer 62. In this way, the support member 80 and the EIC element 60 are electrically connected to each other over a short distance by through vias 55 that penetrate the waveguide substrate 50 in the thickness direction. Furthermore, the support member 80 is provided so as to overlap the EIC element 60 in a plan view. This allows the support member 80 and the EIC element 60 to be connected to each other by a linear path along the thickness direction of the waveguide substrate 50.

[0030] As shown in FIG. 2 , the waveguide component 40 is mounted on the upper surface of the wiring board 20. The waveguide component 40 is mounted on the upper surface of the wiring board 20 by mounting two support members 80 to the connection pads 22 of the wiring board 20. The waveguide component 40 is mounted on the wiring board 20 by bonding the connection pads 84 to the connection pads 22. As shown in FIG. 3 , the connection pads 84 of each support member 80 are electrically connected to the connection pads 22 of the wiring board 20 via solder layers 86. As a result, the support members 80 are electrically connected to the connection pads 22 via the connection pads 84 and the solder layers 86. In this way, each EIC element 60 of the waveguide component 40 is electrically connected to an electronic component 30 via the through vias 55 of the waveguide substrate 50, the through vias 82 of the support members 80, the connection pads 22 of the wiring board 20, etc. As a result, multiple electronic components 30 are connected to each other via the waveguide components 40.

[0031] Here, a gap is provided between the lower surface of each PIC element 70 and the upper surface of the wiring substrate 20. In other words, in the waveguide component 40 of this embodiment, the thickness of each support member 80 is formed to be thicker than the thickness of each PIC element 70 so that a gap is provided between the lower surface of each PIC element 70 and the upper surface of the wiring substrate 20.

[0032] (Configuration of optical fiber 90) As shown in Fig. 1, the optical fiber 90 is provided so as to be connected to the waveguide component 40. The optical fiber 90 is optically connected to the optical waveguide 52 (see Fig. 3) of the waveguide substrate 50. Although not shown, the optical fiber 90 is provided so that, for example, the optical axis of the core of the optical fiber 90 coincides with the optical axis of the core layer 54 (see Fig. 3) of the optical waveguide 52. The optical fiber 90 is, for example, a single-mode fiber.

[0033] In the optical module 10, an optical signal is input from an optical fiber 90 to an optical waveguide 52 (see FIG. 3) of a waveguide substrate 50. The optical signal is input to an optical circuit of a PIC element 70 through the optical waveguide 52. The optical circuit generates a photocurrent corresponding to the input optical signal. As shown in FIG. 3, the photocurrent is input to an electrical circuit of an EIC element 60 through a through via 55 that penetrates the waveguide substrate 50 in the thickness direction. The photocurrent is converted into a voltage signal by the electrical circuit of the EIC element 60, and then converted into a digital signal by a signal processing circuit of the EIC element 60. The digital signal is input to an electronic component 30 through the through via 55 of the waveguide substrate 50, the through via 82 of the support member 80, wiring within the wiring substrate 20, etc.

[0034] (Method of manufacturing the optical module 10) Next, the manufacturing method of the optical module 10 will be explained with reference to Figure 4. Figure 4 is a flowchart showing an example of the manufacturing process of the optical module 10. For the sake of clarity, parts that will ultimately become components of the optical module 10 will be labeled with their final component reference numerals.

[0035] First, in step S1 shown in Fig. 4, a waveguide substrate 50 is formed. Specifically, as shown in Fig. 5, a first clad layer 53A is formed on the lower surface of a substrate 51, and a core layer 54 is formed on the lower surface of the first clad layer 53A. Subsequently, as shown in Fig. 6, a second clad layer 53B is formed on the lower surface of the first clad layer 53A so as to cover the core layer 54. Through the above manufacturing steps, an optical waveguide 52 including a clad layer 53 composed of the first clad layer 53A and the second clad layer 53B and a core layer 54 is formed on the lower surface of the substrate 51. In this way, a waveguide substrate 50 including an optical waveguide 52 can be manufactured.

[0036] Next, in step S2 shown in Fig. 4, a waveguide inspection is performed to check whether the optical waveguide 52 is formed normally. This waveguide inspection determines whether the optical waveguide 52 is good or bad. That is, the waveguide inspection makes it possible to select good products from the manufactured waveguide substrate 50. Note that the waveguide inspection is performed, for example, by irradiating light from one end face in the length direction of the optical waveguide 52 and inspecting whether the light is normally emitted from the other end face in the length direction of the optical waveguide 52.

[0037] Next, in step S3 shown in FIG. 4, a through via 55 and pads 56, 57, and 58 are formed in the waveguide substrate 50 determined to be a non-defective product by the waveguide inspection. Specifically, as shown in FIG. 7, a through hole is formed through the waveguide substrate 50 in the thickness direction, and a through via 55 is formed to fill the through hole. The through hole can be formed by laser processing using, for example, an excimer laser or a YAG laser. The through via 55 can be formed by, for example, electrolytic plating or paste filling. Next, as shown in FIG. 8, a pad 56 is formed on the upper surface of the waveguide substrate 50, specifically on the upper surface of the base material 51, and pads 57 and 58 are formed on the lower surface of the waveguide substrate 50, specifically on the lower surface of the second cladding layer 53B. The pads 56, 57, and 58 can be formed using various wiring formation methods, for example, a semi-additive method or a subtractive method.

[0038] Next, in step S4 shown in FIG. 4, the EIC element 60 is mounted on the waveguide substrate 50. Specifically, as shown in FIG. 9, the EIC element 60 is mounted on the pad 56 of the waveguide substrate 50. More specifically, the electrode pad 61 of the EIC element 60 is bonded to the pad 56 via a solder layer 62. For example, after the waveguide substrate 50 and the EIC element 60 are aligned, a reflow process is performed to melt the solder layer 62, and the electrode pad 61 is electrically connected to the pad 56 via the solder layer 62. The temperature of the reflow process is, for example, about 260°C.

[0039] Next, in step S5 shown in FIG. 4, the PIC element 70 is mounted on the waveguide substrate 50. Next, in step S6, a support member 80 is mounted on the waveguide substrate 50. Specifically, as shown in FIG. 10, the PIC element 70 is mounted on the pad 57 of the waveguide substrate 50, and the support member 80 is mounted on the pad 58 of the waveguide substrate 50. More specifically, using a method similar to that shown in FIG. 9, the electrode pad 71 of the PIC element 70 is bonded to the pad 57 via a solder layer 72, and the connection pad 83 of the support member 80 is bonded to the pad 58 via a solder layer 85. In this step, the PIC element 70 is mounted on the waveguide substrate 50 so that the optical waveguide 52 of the waveguide substrate 50 and the PIC element 70 are optically connected. Furthermore, this step electrically connects the EIC element 60 and the PIC element 70 to each other via a through via 55 that penetrates the waveguide substrate 50 in the thickness direction. The support member 80 may be mounted, for example, at the same time as the PIC element 70, or before the PIC element 70. Furthermore, the PIC element 70 may be mounted, for example, before the EIC element 60.

[0040] Through the above manufacturing process, a waveguide component 40 can be manufactured, which includes a waveguide substrate 50 having an optical waveguide 52, an EIC element 60 mounted on the upper surface of the waveguide substrate 50, and a PIC element 70 and a support member 80 mounted on the lower surface of the waveguide substrate 50.

[0041] Next, in step S7 shown in Figure 4, an optical characteristics test (functional test) is performed on the waveguide component 40. This optical characteristics test determines whether the waveguide component 40 possesses the desired characteristics and functions, and the quality of the waveguide component 40 is determined. In other words, the optical characteristics test allows for the selection of good products (i.e., waveguide components 40 that possess the desired characteristics and functions) from the manufactured waveguide components 40. Here, as shown in Figure 10, the waveguide component 40 has an optical waveguide 52, a PIC element 70 optically connected to the optical waveguide 52, and an EIC element 60 electrically connected to the PIC element 70. Therefore, before the waveguide component 40 is mounted on the wiring board 20 (see Figure 3), it is possible to determine, for example, the quality of the optical connection between the optical waveguide 52 and the PIC element 70, and the quality of the electrical connection between the PIC element 70 and the EIC element 60. In other words, it is possible to determine whether the waveguide component 40, in its state before being mounted on the wiring board 20, possesses the desired characteristics and functions for interconnecting multiple electronic components 30.

[0042] Next, in step S8 shown in Figure 4, the waveguide component 40, which has been determined to be a good product by optical characteristic inspection, is mounted on the wiring board 20. Specifically, as shown in Figure 11, first, a wiring board 20 having connection pads 21 and 22 is prepared. Next, the electronic component 30 is mounted on the connection pad 21. Specifically, the electrode pad 31 of the electronic component 30 is joined to the connection pad 21 via a solder layer 32 in the same manner as the process shown in Figure 9. Then, the waveguide component 40, which has been determined to be a good product by optical characteristic inspection, is placed on top of the wiring board 20. At this time, the waveguide component 40 and the wiring board 20 are aligned so that the connection pad 84 of the support member 80 of the waveguide component 40 and the connection pad 22 of the wiring board 20 are aligned vertically.

[0043] Next, as shown in Figure 12, waveguide components 40 are mounted on the connection pads 22 of the wiring board 20. Specifically, the connection pads 84 of the support member 80 are joined to the connection pads 22 via a solder layer 86 using the same method as shown in Figure 9.

[0044] The optical module 10 of this embodiment can be manufactured through the above manufacturing steps. (Effects of this embodiment) Next, the effects of this embodiment will be described.

[0045] (1-1) The optical module 10 includes a wiring board 20, a plurality of electronic components 30 mounted on the wiring board 20, and a waveguide component 40 mounted on the wiring board 20 and interconnecting the plurality of electronic components 30. The waveguide component 40 has an optical waveguide 52 and includes a waveguide board 50 having a first surface (here, the bottom surface) and a second surface (here, the top surface), and a PIC element 70 mounted on the bottom surface of the waveguide board 50 and optically connected to the optical waveguide 52. The waveguide component 40 also has an EIC element 60 mounted on the top surface of the waveguide board 50 and electrically connected to the PIC element 70.

[0046] In this configuration, the waveguide component 40 mounted on the wiring board 20 includes an optical waveguide 52, a PIC element 70 optically connected to the optical waveguide 52, and an EIC element 60 electrically connected to the PIC element 70. Therefore, optical characteristic testing can be performed on the waveguide component 40 before it is mounted on the wiring board 20. This allows for the determination of the quality of the optical connection between the optical waveguide 52 and the PIC element 70, and the quality of the electrical connection between the PIC element 70 and the EIC element 60, before mounting on the wiring board 20, and determines whether the waveguide component 40 possesses the desired characteristics and functions. Consequently, only waveguide components 40 that are determined to be good products in the optical characteristic testing, including the EIC element 60 and the PIC element 70, can be mounted on the wiring board 20. As a result, even if the number of components mounted on the wiring board 20 increases, a decrease in the final yield of the optical module 10 can be effectively suppressed.

[0047] (1-2) In conventional optical modules, optical connections between optical elements and optical waveguides are made after the optical elements are mounted on the wiring board. Therefore, operational check tests, including optical characteristics, are performed after various components are mounted on the wiring board. Therefore, conventional optical modules have a problem in that defects resulting from operational check tests, including optical characteristics, reduce product yields. In contrast, the optical module 10 of the present embodiment can perform optical characteristic tests on the waveguide component 40 before it is mounted on the wiring board 20, i.e., operational check tests, including optical characteristics. This allows the waveguide component 40 to be evaluated for quality before being mounted on the wiring board 20, and only waveguide components 40 that are evaluated as non-defective can be mounted on the wiring board 20. As a result, a decrease in the yield of the optical module 10 can be effectively prevented.

[0048] (1-3) The waveguide component 40 has a through via 55 that penetrates the waveguide substrate 50 in the thickness direction, and a pad 57 that is formed on the lower surface of the waveguide substrate 50 and is electrically connected to the through via 55. The waveguide component 40 has a pad 56 that is formed on the upper surface of the waveguide substrate 50 and is electrically connected to the pad 57 via the through via 55. The PIC element 70 is mounted on the pad 57. The EIC element 60 is mounted on the pad 56.

[0049] According to this configuration, the PIC element 70 and the EIC element 60 can be electrically connected to each other by through vias 55 that penetrate the waveguide substrate 50 in the thickness direction. This allows the wiring length between the PIC element 70 and the EIC element 60 to be shorter than when the PIC element 70 and the EIC element 60 are arranged side by side on the same plane, thereby favorably improving the electrical characteristics of the optical module 10. For example, high-frequency loss can be suppressed, improving transmission quality, and power consumption can be suppressed.

[0050] (1-4) The wiring board 20 has connection pads 21 electrically connected to the electronic components 30, and connection pads 22 electrically connected to the waveguide components 40 and also electrically connected to the connection pads 21. The waveguide components 40 are formed on the lower surface of the waveguide substrate 50, and have pads 58 electrically connected to the connection pads 22. The EIC element 60 is provided so as to overlap the PIC element 70 in a planar view, and so as to overlap the pads 58 in a planar view.

[0051] According to this configuration, the EIC element 60 and the PIC element 70 are arranged so as to partially overlap each other in a planar view. Therefore, compared to a case where the EIC element 60 and the PIC element 70 are arranged so as not to overlap each other in a planar view, it is possible to suitably prevent the optical module 10 from becoming large in size in the planar direction (i.e., in the direction perpendicular to the thickness direction of the waveguide substrate 50).

[0052] (1-5) The support member 80 has a main body 81 having a third surface (here, the upper surface) and a fourth surface (here, the lower surface). The support member 80 has a through via 82 penetrating the main body 81 in the thickness direction, and a connection pad 83 formed on the upper surface of the main body 81 and electrically connected to the through via 82. The support member 80 has a connection pad 84 formed on the lower surface of the main body 81 and electrically connected to the connection pad 83 via the through via 82. The thickness of the main body 81 is formed to be thicker than the thickness of the PIC element 70. The support member 80 is mounted on the waveguide substrate 50 by bonding the connection pad 83 to the pad 58. The waveguide component 40 is mounted on the wiring substrate 20 by bonding the connection pad 84 to the connection pad 22.

[0053] With this configuration, the main body 81 of the support member 80 is formed to be thicker than the thickness of the PIC element 70, so when the waveguide component 40 is mounted on the wiring board 20, interference between the PIC element 70 and the wiring board 20 can be effectively suppressed. In addition, the pad 58 of the waveguide component 40 and the connection pad 22 of the wiring board 20 can be electrically connected to each other by through vias 82 that penetrate the support member 80 in the thickness direction. This effectively suppresses the increase in wiring length between the pad 58 and the connection pad 22 caused by the provision of the support member 80. As a result, a decrease in electrical characteristics caused by the provision of the support member 80 can be effectively suppressed.

[0054] (1-6) The PIC element 70 is mounted on the lower surface of the waveguide substrate 50 facing the wiring substrate 20, and the EIC element 60 is mounted on the upper surface of the waveguide substrate 50. As a result, the PIC element 70, which generates less heat than the EIC element 60, is housed in the space enclosed by the wiring substrate 20, the support member 80, and the waveguide substrate 50. Therefore, heat buildup in the space enclosed by the wiring substrate 20, the support member 80, and the waveguide substrate 50 can be effectively suppressed.

[0055] (Second embodiment) The second embodiment will be described below with reference to Figure 13. Components identical to those shown in Figures 1 to 12 will be denoted by the same reference numerals, and detailed explanations of each of these elements will be omitted. The following explanation will focus on the differences from the first embodiment.

[0056] As shown in Figure 13, the optical module 10A of this embodiment includes a wiring board 20A, a plurality of electronic components 30 mounted on the wiring board 20A, and a waveguide component 40A mounted on the wiring board 20A.

[0057] (Configuration of wiring board 20A) The wiring board 20A has connection pads 21 and 22 and a recess 20X. The recess 20X is formed to be recessed downward from the surface (here, the upper surface) of the wiring board 20A on which the connection pads 21 and 22 are formed. The recess 20X is formed to a size capable of accommodating the PIC element 70 of the waveguide component 40A.

[0058] (Configuration of waveguide component 40A) The waveguide component 40A has a waveguide substrate 50, through vias 55, pads 56, 57, and 58, a plurality of EIC elements 60 mounted on the upper surface of the waveguide substrate 50, and a plurality of PIC elements 70 mounted on the lower surface of the waveguide substrate 50. The waveguide component 40A of this embodiment does not have the support member 80 of the waveguide component 40 of the first embodiment.

[0059] Waveguide component 40A is mounted on the upper surface of the wiring board 20A. Waveguide component 40A is mounted on the upper surface of the wiring board 20A by bonding a pad 58 provided on the lower surface of the waveguide board 50 to a connection pad 22 of the wiring board 20A. For example, the pad 58 of waveguide component 40A is electrically connected to the connection pad 22 of the wiring board 20A via a solder layer 59. As a result, each EIC element 60 of waveguide component 40A is electrically connected to the connection pad 22 of the wiring board 20A via an electrode pad 61, a solder layer 62, a pad 56, a through-via 55, a pad 58, and a solder layer 59.

[0060] The waveguide component 40A is mounted on the wiring board 20A, for example, so that the PIC elements 70 are housed in the recesses 20X. Here, the depth of the recesses 20X is formed to be deeper than the thickness of each PIC element 70. This provides a gap between the lower surface of each PIC element 70 and the bottom surface of the recesses 20X.

[0061] According to the embodiment described above, in addition to the effects (1-1) to (1-4) of the first embodiment, the following effects can be achieved. (2-1) The wiring board 20A has a recess 20X provided on its upper surface where connection pads 21 and 22 are formed. The depth of the recess 20X is greater than the thickness of the PIC element 70. Waveguide components 40A are mounted on the wiring board 20A such that the PIC element 70 is housed in the recess 20X.

[0062] With this configuration, since the depth of the recess 20X is formed to be greater than the thickness of the PIC element 70, interference between the PIC element 70 and the wiring board 20A can be effectively suppressed when the waveguide component 40A is mounted on the wiring board 20A. Specifically, contact between the lower surface of the PIC element 70 and the bottom surface of the recess 20X can be effectively suppressed.

[0063] (2-2) The pad 58 of the waveguide component 40 is joined to the connection pad 22 of the wiring board 20A. With this configuration, the wiring length between the pad 58 and the connection pad 22 can be shortened compared to when a support member 80 is provided, and thus the electrical characteristics of the optical module 10 can be suitably improved.

[0064] (Example of change) The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0065] The structure of the support member 80 in the first embodiment can be modified as needed. In the optical module 10 of the first embodiment described above, two support members 80 are provided, but the invention is not limited to this. For example, one annular support member 80 may be provided. In this case, the support member 80 is formed to surround the outer periphery of the multiple PIC elements 70.

[0066] For example, the waveguide component 40B of the optical module 10B shown in FIG. 14 may be modified to have a structure including a support member 80A formed on the lower surface of the waveguide substrate 50. The support member 80A has a sealing resin 81A formed on the lower surface of the waveguide substrate 50 so as to seal the PIC element 70. The thickness of the sealing resin 81A is greater than the thickness of the PIC element 70. The sealing resin 81A is formed so as to cover the entire surface of the PIC element 70. The sealing resin 81A is formed so as to cover the entire upper, side, and lower surfaces of the PIC element 70. The sealing resin 81A is formed so as to seal the pads 57 and 58. The sealing resin 81A is formed so as to cover the lower surface of the waveguide substrate 50. The sealing resin 81A is formed so as to fill the gap between the lower surface of the waveguide substrate 50 and the upper surface of the PIC element 70.

[0067] The material of the sealing resin 81A may be, for example, a non-photosensitive insulating resin containing a thermosetting resin as a main component. The material of the sealing resin 81A may be, for example, an insulating resin such as an epoxy resin or a polyimide resin, or a resin material in which a filler such as silica or alumina is mixed into such a resin. The sealing resin 81A may be, for example, a mold resin.

[0068] The support member 80A has a plurality of through vias 82A that penetrate the sealing resin 81A in the thickness direction, and a plurality of connecting pads 84A provided on the lower surface of the sealing resin 81A. Each through via 82A is formed to fill a through hole that penetrates the sealing resin 81A in the thickness direction and exposes a portion of the lower surface of the pad 58. Each through via 82A is electrically connected to the pad 58. Each connecting pad 84A is electrically connected to the pad 58 via the through via 82A.

[0069] The waveguide component 40B is mounted on the upper surface of the wiring substrate 20. The waveguide component 40B is mounted on the upper surface of the wiring substrate 20 by mounting the support member 80A to the connection pads 22 of the wiring substrate 20. The waveguide component 40B is mounted on the upper surface of the wiring substrate 20 by bonding the connection pads 84A of the support member 80A to the connection pads 22. Specifically, the connection pads 84A of the support member 80A are electrically connected to the connection pads 22 via solder layers 86A. In this way, each EIC element 60 of the waveguide component 40B is electrically connected to the electronic component 30 via the through vias 55 of the waveguide substrate 50, the through vias 82A of the support member 80A, the connection pads 22 of the wiring substrate 20, etc.

[0070] The structure of the waveguide substrate 50 in each of the above embodiments can be modified as appropriate. For example, the base material 51 may be omitted. For example, the waveguide substrate 50A in the waveguide component 40C of the optical module 10C shown in FIG. 15 may be modified to have a structure including a support substrate 51A and an optical waveguide 52 formed on the support substrate 51A.

[0071] The support substrate 51A is, for example, a substrate having higher rigidity than the optical waveguide 52. As the support substrate 51A, for example, a woven or nonwoven fabric of glass fiber, aramid fiber, or the like, impregnated with an insulating resin such as an epoxy resin can be used.

[0072] The optical waveguide 52 of this modified example is, for example, a polymer optical waveguide. In this case, the cladding layer 53 and the core layer 54 may be made of an acrylic resin such as polymethyl methacrylate (PMMA), an epoxy resin, or a silicone resin. However, in order to ensure that the optical signal propagates only within the core layer 54, a material having a higher refractive index than the material of the cladding layer 53 is selected for the core layer 54.

[0073] According to this configuration, the rigidity of the waveguide substrate 50A can be increased by the support substrate 51A, and therefore the optical waveguide 52 formed on the lower surface of the support substrate 51A can be made thin.

[0074] In the optical modules 10, 10A of the above embodiments, the optical component connected to the waveguide component 40, 40A is embodied as an optical fiber 90, but this is not limiting. For example, the optical component connected to the waveguide component 40, 40A may be embodied as an optical connector. In this case, the optical connector is joined to the waveguide component 40, 40A, for example. The optical connector is configured to be connectable to, for example, an external optical component or an external light source. For example, the optical connector is configured to be detachable from a mating connector provided at the end of an optical fiber.

[0075] In the optical modules 10 and 10A of the above embodiments, an underfill resin may be provided to fill the gap between the lower surface of the waveguide substrate 50 and the PIC element 70. In the optical modules 10 and 10A of the above embodiments, a heat dissipation component such as a heat sink may be mounted on the top surface of the EIC element 60.

[0076] The mounting form of the support member 80 in the first embodiment can be changed as appropriate. In the above embodiments, the EIC element 60 is mounted on the waveguide substrate 50 using a flip-chip mounting method, but this is not the only option. For example, the EIC element 60 may be mounted on the waveguide substrate 50 by wire bonding or soldering.

[0077] In the embodiments described above, the PIC element 70 is mounted on the waveguide substrate 50 using a flip-chip mounting method, but this is not the only way to do so. For example, the PIC element 70 may be mounted on the waveguide substrate 50 by wire bonding or soldering.

[0078] In the embodiments described above, the electronic component 30 is mounted on the wiring board 20 using a flip-chip mounting method, but the invention is not limited to this. For example, the electronic component 30 may be mounted on the wiring board 20 by wire bonding or soldering.

[0079] The numbers of electronic components 30, EIC elements 60, and PIC elements 70 in the optical modules 10 and 10A of the above embodiments are not particularly limited. In the optical modules 10 and 10A of the above embodiments, the mounting positions of the EIC element 60 and the PIC element 70 may be interchanged. That is, the PIC element 70 may be mounted on the upper surface of the waveguide substrate 50, and the EIC element 60 may be mounted on the lower surface of the waveguide substrate 50. [Explanation of symbols]

[0080] 10, 10A, 10B, 10C Optical Modules 20,20A Wiring Board 21. Connection pad (1st connection pad) 22 Connection pad (2nd connection pad) 30 Electronic Components 40, 40A, 40B, 40C Waveguide components 50,50A Waveguide Board 52 Optical waveguide 55 Through via (first through via) 56 Pad (2nd Pad) 57 Pad (1st Pad) 58 Pad (3rd Pad) 60 EIC elements (Electrical Integrated Circuit elements) 70 PIC element (optical integrated circuit element) 80,80A Support member 81 Main body 81A Sealing resin 82 Through via (second through via) 82A Through via (third through via) 83 Connection Pad (Third Connection Pad) 84 connection pad (4th connection pad) 84A connection pad (5th connection pad) 90 Optical Fiber

Claims

1. A wiring board; a plurality of electronic components mounted on the wiring board; a waveguide component mounted on the wiring board and connecting the plurality of electronic components to each other, The waveguide component comprises: a waveguide substrate having an optical waveguide and having a first surface and a second surface opposite to the first surface; an optical integrated circuit element mounted on the first surface of the waveguide substrate and optically connected to the optical waveguide; an electrical integrated circuit element mounted on the second surface of the waveguide substrate and electrically connected to the optical integrated circuit element.

2. The waveguide component comprises: a first through via that penetrates the waveguide substrate in a thickness direction; a first pad formed on the first surface of the waveguide substrate and electrically connected to the first through via; a second pad formed on the second surface of the waveguide substrate and electrically connected to the first pad through the first through via; the optical integrated circuit element is mounted on the first pad, 2. The optical module according to claim 1, wherein the electrical integrated circuit element is mounted on the second pad.

3. the wiring board has a first connection pad electrically connected to the electronic component, and a second connection pad electrically connected to the waveguide component and the first connection pad, the waveguide component has a third pad electrically connected to the second connection pad; 3. The optical module according to claim 2, wherein the electrical integrated circuit element is provided so as to overlap the optical integrated circuit element in a plan view, and is also provided so as to overlap the third pad in a plan view.

4. the waveguide component has a support member provided on the first surface of the waveguide substrate, the third pad is formed on the first surface of the waveguide substrate, the thickness of the support member is formed to be thicker than the thickness of the optical integrated circuit element; The optical module according to claim 3 , wherein the support member is mounted on the second connection pad.

5. The support member is a main body portion having a third surface and a fourth surface opposite to the third surface; a second through via that penetrates the body in a thickness direction; a third connection pad formed on the third surface of the main body and electrically connected to the second through via; a fourth connection pad formed on the fourth surface of the main body and electrically connected to the third connection pad through the second through via; the thickness of the main body is formed to be thicker than the thickness of the optical integrated circuit element, the support member is mounted on the waveguide substrate by bonding the third connection pad to the third pad, 5. The optical module according to claim 4, wherein the waveguide component is mounted on the wiring board by bonding the fourth connection pad to the second connection pad.

6. The optical module according to claim 5 , wherein the third pad is electrically connected to the second pad through the first through via.

7. The support member is a sealing resin formed on the first surface of the waveguide substrate so as to seal the optical integrated circuit element; a third through via that penetrates the sealing resin in a thickness direction and is electrically connected to the third pad; 5. The optical module according to claim 4, further comprising: a fifth connection pad bonded to the second connection pad and electrically connecting the second connection pad and the third through via.

8. the wiring substrate has a recess provided on a surface of the wiring substrate on which the first connection pads and the second connection pads are formed, The depth of the recess is formed to be deeper than the thickness of the optical integrated circuit element, the waveguide component is mounted on the wiring board so that the optical integrated circuit element is housed in the recess, The optical module according to claim 3 , wherein the third pad is bonded to the second connection pad.

9. 2. The optical module according to claim 1, further comprising an optical fiber optically connected to said optical waveguide.

10. forming a waveguide substrate having an optical waveguide and having a first surface and a second surface opposite the first surface; performing a waveguide inspection on the waveguide substrate; mounting an electrical integrated circuit element on the second surface of the waveguide substrate; mounting an optical integrated circuit element on the first surface of the waveguide substrate, the optical integrated circuit element being optically connected to the optical waveguide and electrically connected to the electrical integrated circuit element; a step of carrying out an optical characteristic inspection on a waveguide component having the waveguide substrate, the electrical integrated circuit element, and the optical integrated circuit element; and mounting the waveguide component on a wiring board.

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