Wiring board

Abstract

A wiring board (1) according to an embodiment includes: an electrical wiring section (2) including insulating layers (21, 22, 32) and conductor layers (11, 12, 31); an optical wiring part (3) disposed on one surface (2a) of the electrical wiring part (2); and a component region (CA) in which the component (E1) can be disposed on the optical wiring section (3). The optical wiring section (3) includes: an optical waveguide (5) including a core section (51) and a cladding section (52); and a support substrate (6) including a conductor region (CA) having a conductor, the support substrate (6) having a first surface (6b) on the side on which the component (E1) is arranged and a second surface (6a) on the side on which the electrical wiring section (2) is arranged, the support substrate (6) having a coefficient of thermal expansion lower than the coefficient of thermal expansion of the optical waveguide (5), and a non-conductor region (NC) in which the optical waveguide (5) is formed on the first surface (6b) of the support substrate (6). The conductor region (CA) includes a through conductor (61) penetrating between the first surface (6b) of the support substrate (6) and the second surface (6a) of the support substrate (6).

Description

Technical Field

[0001] The present invention relates to a wiring substrate. Background Art

[0002] Patent document 1 discloses a substrate for mounting optical components with an optical waveguide mounted on the surface. The optical waveguide having a core and a cladding layer is arranged on an interlayer insulating layer exposed on the surface of a wiring substrate. The optical waveguide is positioned so that the end of the core is optically coupled with the light emitting portion (or light receiving portion) of an optical semiconductor element mounted on the wiring substrate. The optical semiconductor element is mounted by connecting its bump to the connection portion of the wiring pattern of the wiring substrate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-129385 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the substrate disclosed in Patent Document 1, an optical waveguide formed of a polyimide resin, an epoxy resin, or the like sometimes cannot be properly positioned at a predetermined position on a wiring substrate. In this case, it is believed that the core of the waveguide and the light-emitting portion (or light-receiving portion) of the optical semiconductor element cannot be optically coupled with sufficient efficiency. In addition, sometimes a positional offset occurs between the optical semiconductor element and the waveguide due to the expansion and contraction of the interlayer insulating layer, and the efficiency of optical coupling is reduced. Furthermore, a positional offset is also likely to occur in the thickness direction of the substrate between the optical semiconductor element arranged on the interlayer insulating layer via a wiring pattern, a connection portion composed of plated metal, and a bump, and the optical waveguide arranged on the interlayer insulating layer, and the optical coupling efficiency is sometimes further reduced.

[0008] Means for solving problems

[0009] The wiring substrate of the present invention includes: an electric wiring portion including an insulating layer and a conductor layer; an optical wiring portion placed on one surface of the electric wiring portion; and a component region capable of arranging components on the optical wiring portion. The optical wiring portion includes: an optical waveguide including a core portion and a cladding portion; and a support substrate including a conductor region having a conductor and a non-conductor region, the support substrate having a first surface on the side where the components are arranged and a second surface on the side of the electric wiring portion, the support substrate having a thermal expansion coefficient lower than that of the optical waveguide, the optical waveguide being formed on the first surface of the support substrate in the non-conductor region, and a through conductor penetrating between the first surface of the support substrate and the second surface of the support substrate in the conductor region.

[0010] According to the embodiment of the present invention, the positional deviation between the optical waveguide of the optical wiring portion of the wiring substrate and the optical component optically coupled to the optical waveguide can be suppressed, and the coupling efficiency can be improved or suppressed. In addition, sometimes the optical component can be easily mounted on the wiring substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a cross-sectional view showing an example of a wiring substrate according to an embodiment of the present invention.

[0012] Figure 2 yes Figure 1 An enlarged view of part II.

[0013] Figure 3 It is shown Figure 1 This is a top view of an example of an optical wiring portion when viewed from above.

[0014] Figure 4A A cross-sectional view showing another example of the optical wiring portion in the wiring substrate according to the embodiment.

[0015] Figure 4B A cross-sectional view showing another example of the optical wiring portion in the wiring substrate according to the embodiment.

[0016] Figure 4C A cross-sectional view showing another example of the optical wiring portion in the wiring substrate according to the embodiment.

[0017] Figure 4D A cross-sectional view showing another example of the optical wiring portion in the wiring substrate according to the embodiment.

[0018] Figure 5 It is shown Figure 4A This is a top view of an example of an optical wiring portion when viewed from above.

[0019] Figure 6 This is a cross-sectional view showing another example of the through conductor in the wiring substrate according to the embodiment.

[0020] Fig. 7A It is a cross-sectional view showing an example of a manufacturing process of the optical wiring portion in the wiring substrate according to the embodiment.

[0021] Figure 7B It is a cross-sectional view showing an example of a manufacturing process of the optical wiring portion in the wiring substrate according to the embodiment.

[0022] Figure 7C It is a cross-sectional view showing an example of a manufacturing process of the optical wiring portion in the wiring substrate according to the embodiment.

[0023] Fig.7D It is a cross-sectional view showing an example of a manufacturing process of the optical wiring portion in the wiring substrate according to the embodiment.

[0024] Fig. 7E It is a cross-sectional view showing an example of a manufacturing process of the optical wiring portion in the wiring substrate according to the embodiment.

[0025] Figure 7F It is a cross-sectional view showing an example of a manufacturing process of the wiring substrate according to the embodiment.

[0026] Figure 7G This is a cross-sectional view showing an example of a process of mounting components after the wiring substrate of the embodiment is completed.

[0027] Fig. 8A It is a cross-sectional view showing a modified example of the wiring substrate according to the embodiment of the present invention.

[0028] Figure 8B It is a plan view showing a modified example of the arrangement of through conductors in the wiring substrate according to the embodiment. DETAILED DESCRIPTION

[0029] A wiring board according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 is a cross-sectional view showing a wiring substrate 1 as an example of a wiring substrate according to an embodiment. Figure 2 Shown in Figure 1 An enlarged view of part II. Figure 3 Show Figure 1 The wiring substrate 1 of the embodiment is an example of a plan view of an optical wiring portion included in the wiring substrate 1. The “plan view” refers to observing the wiring substrate of the embodiment along the line of sight in the thickness direction. In addition, the wiring substrate 1 is only an example of the wiring substrate of the embodiment. The stacked structure of the wiring substrate of the embodiment and the number of conductor layers and insulating layers are not limited to Figure 1 The stacked structure of the wiring substrate 1 and the number of conductor layers and insulating layers included in the wiring substrate 1 are shown. In addition, in the various drawings referred to in the following description, in order to facilitate the understanding of the disclosed embodiments, specific parts are sometimes enlarged and depicted, and the sizes and lengths of the various structural elements are sometimes not depicted in an accurate ratio with respect to each other.

[0030] like Figure 1 As shown, the wiring substrate 1 includes an electric wiring portion 2 and an optical wiring portion 3 placed on one surface 2a of the electric wiring portion 2. The electric wiring portion 2 includes an insulating layer and a conductor layer. Specifically, Figure 1The electric wiring portion 2 of the example includes: a core substrate 30 having two surfaces 30a and 30b opposite to each other in the thickness direction thereof; an insulating layer 21 and a conductor layer 11, which are sequentially stacked on the surface 30a of the core substrate 30; and an insulating layer 22 and a conductor layer 12, which are sequentially stacked on the surface 30b. Via conductors 26 are formed in the insulating layer 21 and the insulating layer 22, respectively, to connect the conductor layers sandwiched therebetween. The core substrate 30 includes an insulating layer 32 and conductor layers 31 formed on both sides of the insulating layer 32. A through-hole conductor 33 is provided in the insulating layer 32 to penetrate the insulating layer 32 and connect the conductor layers 31 on both sides. The interior of the cylindrical through-hole conductor 33 is filled with a filler 34, which is formed of, for example, an insulating resin such as epoxy resin or a conductive resin containing metal particles.

[0031] In the description of the embodiment, the side away from the insulating layer 32 in the thickness direction of the wiring substrate 1 is also referred to as the "upper side" or "above", or simply "upper", and the side close to the insulating layer 32 is also referred to as the "lower side" or "below", or simply "lower". In addition, in each conductor layer and each insulating layer, the surface facing the side opposite to the insulating layer 32 is also referred to as the "upper surface", and the surface facing the insulating layer 32 side is also referred to as the "lower surface". The thickness direction of the wiring substrate 1 is also referred to as the "Z direction".

[0032] The electric wiring portion 2 includes a solder resist 23 formed on the surface 30a side of the core substrate 30 and a solder resist 24 formed on the surface 30b side. The surface 2a of the electric wiring portion 2 is mainly composed of the upper surface of the solder resist 23. The solder resist 23 partially covers the insulating layer 21 and the conductor layer 11, respectively, and the solder resist 24 partially covers the insulating layer 22 and the conductor layer 12, respectively. The solder resist 23 has an opening 23a that exposes a portion of the conductor layer 11. Similarly, the solder resist 24 also has an opening 24a.

[0033] The electric wiring portion 2 includes a conductive bump 25 formed in the opening 23a of the solder resist 23 so as to contact the conductor layer 11. The conductive bump 25 is formed using, for example, tin-based solder, gold-based solder, etc. The conductive bump 25 is used to electrically and mechanically connect the electrode E2a of the component E2 mounted on the outside of the wiring substrate 1 to the portion of the conductor layer 11 exposed in the opening 23a.

[0034] The insulating layers 21, 22 and the insulating layer 32 can be formed using, for example, a thermosetting insulating resin such as an epoxy resin, a bismaleimide triazine resin (BT resin) or a phenolic resin. The insulating layers 21, 22 and the insulating layer 32 can also be formed using a thermoplastic insulating resin such as a fluororesin, a liquid crystal polymer (LCP), a fluorinated polyethylene (PTFE) resin, a polyester (PE) resin and a modified polyimide (MPI) resin. Although not shown, each insulating layer may include a core material (reinforcement material) formed of glass fiber, aramid fiber, etc., and may also include an inorganic filler composed of microparticles such as silicon dioxide (SiO2), alumina or mullite. On the other hand, the solder resists 23 and 24 are formed of, for example, a photosensitive epoxy resin, a polyimide resin, etc.

[0035] The conductor layers 11 and 12, the conductor layer 31, the through-hole conductor 33, and the via-hole conductor 26 can be formed using any metal such as copper or nickel. Figure 1 Although it is simplified and depicted as one layer, it can also be a multilayer structure including two or more film bodies. For example, the conductor layers 11 and 12 can also be a two-layer structure including a chemical plating film and an electroplating film. In addition, the metal used for the electrical wiring formed on the wiring substrate 1 is called a "conductor".

[0036] The conductor layers 11, 12 and the conductor layer 31 may each include an arbitrary conductor pattern. Figure 1 In the example of FIG. 1 , the conductor layer 11 includes conductor pads 11a and 11b. The conductor pads 11a and 11b are exposed in the opening 23a of the solder resist 23. Figure 1 The electric wiring portion 2 has conductors exposed on one surface 2a such as the conductor pads 11a and 11b. The electrode E2a of the component E2 is connected to the conductor pad 11b via the conductive bump 25.

[0037] When using the wiring substrate 1, Figure 1 to Figure 3 Therefore, the surface 2a of the electric wiring portion 2 has a component area A1 covered by the component E1 when viewed from above when the wiring substrate 1 is used. The component E1 mounted in the component area A1 is an electrical component including a light receiving element and / or a light emitting element having a photoelectric conversion function. Figure 1 to Figure 3 The component E1 of the example includes an electrode E1a and a light receiving portion or a light emitting portion E1b. The light receiving portion or the light emitting portion E1b has a light receiving surface or a light emitting surface E1c facing the side and the bottom of the component E1 (see Figure 2 ). The electrode E1a and the light receiving portion or light emitting portion E1b are provided on the surface of the component E1 facing the wiring substrate 1. Figure 1 to Figure 3 In the example of FIG. 1 , the component E1 is mounted so-called face-down (flip-chip mounting).

[0038] As the component E1, a light receiving element such as a photodiode and a light emitting element such as a light emitting diode (LED), an organic light emitting diode (OLED), a laser diode (LD), and a vertical resonance surface emitting laser (VCSEL) are exemplified. When the component E1 is a light emitting element, the component E1 generates a light signal based on the electric signal input to the electrode E1a, and emits the light signal from the light receiving part or the light emitting part E1b functioning as the light emitting part. In addition, when the component E1 is a light receiving element, an electric signal based on the light signal incident to the light receiving part or the light emitting part E1b functioning as the light receiving part is generated and output from the electrode E1a.

[0039] Component E2 may be, for example, an electronic component such as a semiconductor device that generates an electrical signal for causing component E1 to emit light and / or processes the electrical signal generated by component E1. Component E2 includes, for example, a semiconductor device such as a general-purpose operational amplifier, a driver IC, a microcomputer, a programmable logic device (PLD), and the like.

[0040] The optical wiring portion 3 arranged on the electric wiring portion 2 includes a support substrate 6 and an optical waveguide 5. The support substrate 6 is arranged on the upper surface of the solder resist 23 constituting one surface 2a of the electric wiring portion 2 via a connection material 7. The support substrate 6 includes a conductor area CA having a conductor and a non-conductor area NC. The support substrate 6 has a first surface 6b on the component area A1 side which is a side where the component E1 is arranged, and a second surface 6a which is the opposite surface of the first surface 6b and faces the electric wiring portion 2 side. In the present embodiment, the support substrate 6 has a thermal expansion coefficient lower than that of the optical waveguide 5. In the conductor area CA, as a conductor of the support substrate 6, a through conductor 61 is included which penetrates between the first surface 6b and the second surface 6a.

[0041] The through conductor 61 is formed of any conductive material. For example, the through conductor 61 may include metals such as copper, nickel, aluminum, tin, and gold, alone or in combination. The through conductor 61 may also be a cured body of a conductive paste made of a resin such as epoxy resin containing conductive particles such as silver and copper. Figure 2 ) After forming an insulating layer, a plating film is formed. The through conductor 61 may be filled with a conductive material, or a conductive material may be formed along the inner wall of the outer periphery of the through hole 60, with the center being a hollow. As long as conduction can be achieved between the front and back surfaces of the support substrate 6, the form of the through conductor 61 is not limited. Figure 1 to Figure 3 In the example of FIG. 1 , the through conductor 61 has a connection portion 61 a connected to the electrode E1 a of the component E1 .

[0042] In the non-conductor region NC, an optical waveguide 5 is formed on the first surface 6b of the support substrate 6. The optical waveguide 5 is arranged on the support substrate 6. The optical waveguide 5 includes a core 51 that transmits an optical signal and a cladding 52 that surrounds the core 51. The cladding 52 is provided around the core 51, and sandwiches the core 51 in an arbitrary direction perpendicular to the extension direction of the core 51, that is, the propagation direction of the light in the core 51. In addition, the propagation direction of the light is the +X direction or the -X direction, which is also referred to as the "X direction" hereinafter.

[0043] The cladding portion 52 includes: a lower cladding layer 521, which constitutes a portion on the support substrate 6 side of the core portion 51; and an upper cladding layer 522, which is a portion on the upper side of the lower cladding layer 521 and constitutes a portion on the side farther from the support substrate 6 than the lower cladding layer 521. The upper surface (the surface on the side opposite to the support substrate 6) and the side surface of the core portion 51 are covered by the upper cladding layer 522. However, a portion of the core portion of the core portion 51 is not covered by the upper cladding layer 522, and is partially exposed from the cladding portion 52 on the lower cladding layer 521.

[0044] The core 51 and the cladding 52 are formed using a material having an appropriate refractive index. The core 51 and the cladding 52 can be made of, for example, an organic material (organic matter), an inorganic material (inorganic matter), or an organic-inorganic mixed material containing an organic component and an inorganic component such as an inorganic polymer. Examples of the inorganic material include quartz glass and silicon, and examples of the organic material include acrylic resins such as polymethyl methacrylate (PMMA), polyimide resins, polyamide resins, polyether resins, and epoxy resins. The optical waveguide 5 made of an organic matter is easy to be lightweight and has high toughness.

[0045] The core 51 and the cladding 52 may be made of different materials or the same system of materials. However, the core 51 uses a material having a higher refractive index than the material used for the cladding 52 so that light can be totally reflected at the interface between the core 51 and the cladding 52. The core 51 and the cladding 52 may be formed of materials having the same refractive index and then subjected to appropriate treatment to make their refractive indices different from each other.

[0046] As an example, the optical waveguide 5 can be formed on the support substrate 6. For example, the optical waveguide 5 and the support substrate 6 can be bonded by curing the material of the semi-cured coating portion 52 on the support substrate 6. In addition, the optical waveguide 5 can also be formed independently of the support substrate 6, for example, and fixed to the support substrate 6 using any adhesive (not shown). However, the method for fixing the optical waveguide 5 and the support substrate 6 is not particularly limited. The optical waveguide 5 can be fixed to the support substrate 6 in any manner.

[0047] The core 51 has a first end 5a and a second end 5b which is an end on the opposite side of the first end 5a. Figure 1 to Figure 3 In the example of , the first end portion 5a overlaps with the component area A1 when viewed from above. The core portion 51 extends from the component area A1 toward the outer edge of the electric wiring portion 2. The core portion 51 is exposed from the covering portion 52 on the lower covering layer 521 at the first end portion 5a. That is, the upper covering layer 522 of the covering portion 52 is not formed to the edge of the lower covering layer 521 on the first end portion 5a side. Therefore, at the first end portion 5a, not only the end face of the core portion 51, but also the upper surface and the side surface of the core portion 51 are exposed from the covering portion 52.

[0048] In the first end portion 5a, the core portion 51 is positioned so as to face the light receiving portion or the light emitting portion E1b of the component E1 when the wiring substrate 1 is used. Specifically, the core portion 51 is positioned so that the upper surface 51a (see Figure 2 ) is optically coupled (hereinafter also referred to as "optical coupling") to the surface of the light-receiving surface or the light-emitting surface E1c of the component E1 that faces the support substrate 6. In this way, when the wiring substrate 1 is used, the core 51 is optically coupled to the component E1. In addition, the optical waveguide in which the core 51 of the optical waveguide is exposed at the end of the optical waveguide and the component having a light-receiving surface or a light-emitting surface formed on the side of the component can also be optically coupled by end-face connection. On the other hand, the end face on the side of the second end 5b of the core 51 is positioned so that when the wiring substrate 1 is used, it is opposed to the optical fiber F connected to the optical waveguide 5 using the connector C and optically coupled.

[0049] Since the optical waveguide 5 is positioned in this way, the optical signal propagating in the optical fiber F enters the optical waveguide 5 from the second end 5b of the core 51, enters the component E1 from the first end 5a via the light receiving portion or light emitting portion E1b, and is converted into an electrical signal in the component E1. On the other hand, the electrical signal input into the component E1 via the electrode E1a is converted into an optical signal in the component E1. The optical signal is emitted from the light receiving portion or light emitting portion E1b, enters the optical waveguide 5 from the first end 5a, and is emitted to the optical fiber F from the second end 5b.

[0050] In the present embodiment, the optical wiring section 3 has a supporting substrate 6, and the optical waveguide 5 is arranged on the supporting substrate 6. Therefore, it is considered that the first end 5a and the second end 5b of the core 51 of the optical waveguide 5 are easily positioned at a position where they can be optically coupled with the light receiving part or the light emitting part E1b of the component E1, or the optical fiber F with sufficient efficiency. That is, the optical waveguide used in the optical wiring section 3, which is made of any material such as various resins, sometimes has high flexibility. Therefore, in Patent Document 1, it is sometimes difficult to position and fix the optical waveguide alone at an appropriate position. As a result, sufficient coupling efficiency may not be obtained in the optical coupling between the optical waveguide and the optical component and / or the optical fiber.

[0051] In contrast, in the present embodiment, the optical wiring portion 3 includes a support substrate 6, and the optical waveguide 5 is formed in the non-conductor region NC of the first surface 6b of the support substrate 6. Therefore, the optical waveguide 5 is arranged on the support substrate 6. Therefore, the optical waveguide 5 can be easily positioned at an appropriate position. Therefore, it is considered that the optical waveguide 5 is optically coupled with the component E1 and the optical fiber F with sufficient efficiency. The support substrate 6 preferably has a higher rigidity than the optical waveguide 5. It is inferred that the optical waveguide 5 can be more easily positioned at an appropriate position. Specifically, the first end 5a and the second end 5b of the core 51 of the optical waveguide 5 can be easily positioned at an appropriate position.

[0052] In this embodiment, the support substrate 6 has a thermal expansion coefficient lower than that of the optical waveguide 5. Generally speaking, an optical waveguide has a thermal expansion coefficient corresponding to its own constituent material, and therefore its core may be relatively displaced relative to the optical fiber and / or optical component combined therewith according to the ambient temperature change. Therefore, even if the optical waveguide is properly positioned relative to the optical fiber and / or optical component, the efficiency of optical coupling between the optical waveguide and the optical fiber and optical component may be reduced when the wiring substrate is used.

[0053] In contrast, in the present embodiment, the support substrate 6 supporting the optical waveguide 5 in the optical wiring section 3 has a lower thermal expansion coefficient than the optical waveguide 5. Therefore, it is possible to suppress the displacement of the core 51 of the optical waveguide 5 caused by the ambient temperature change. Therefore, it is considered that the positional displacement of the optical waveguide 5 and the optical fiber F and / or the component E1 under the environment of temperature change can be suppressed. In this way, according to the present embodiment, it is considered that the positional displacement between the optical waveguide 5 included in the wiring substrate 1 and the component E1 optically coupled to the optical waveguide 5 can be suppressed, and the efficiency of optical coupling can be improved or the reduction of the efficiency of optical coupling can be suppressed.

[0054] In addition, when the core 51 and the cladding 52 have different thermal expansion coefficients, the thermal expansion coefficient of the support substrate 6 is lower than the average value of the thermal expansion coefficients of the core 51 and the cladding 52. Preferably, the thermal expansion coefficient of the support substrate 6 is lower than the thermal expansion coefficient of the lower one of the thermal expansion coefficients of the core 51 and the cladding 52. The support substrate 6 can be composed of any material so as to have such a lower thermal expansion coefficient than the optical waveguide 5, and preferably has a higher rigidity than the optical waveguide 5. For example, the support substrate 6 has a bending rigidity higher than the bending rigidity of the optical waveguide 5. The material of the support substrate 6 is preferably an inorganic material. Examples of the material of the support substrate 6 include glasses such as soda lime glass, borosilicate glass, and quartz glass, various ceramics such as aluminum oxide, silicon nitride, and silicon oxide, and semiconductors such as silicon and germanium.

[0055] The thermal expansion coefficient of the optical waveguide 5 is, for example, 10 ppm / °C to 100 ppm / °C. In contrast, the thermal expansion coefficient of the support substrate 6 is, for example, 3 ppm / °C to 10 ppm / °C. The bending rigidity of the support substrate 6 is, for example, 1.1 times or more of the bending rigidity of the optical waveguide 5 and 2 times or less of the bending rigidity of the electric wiring portion 2. It is considered that the optical waveguide 5 can be held in an easy-to-handle manner, and the optical wiring portion 3 can follow the warping of the electric wiring portion 2 to some extent. The thickness of the support substrate 6 is not particularly limited, and can be, for example, about 30 μm to 1000 μm.

[0056] Continue to refer to Figure 2 as well as Figure 3 , an example of the structure of the support substrate 6 of the optical wiring section 3 and the optical coupling and electrical connection between the wiring substrate 1 and the component E1 will be described. Figure 2 and Figure 3 As shown, the component E1 is arranged so that the light receiving portion or light emitting portion E1b is opposite to the first end portion 5a of the core portion 51 of the optical waveguide 5. In addition, the component E1 is arranged so that the electrode E1a is located in the region where the optical waveguide 5 is not formed on the first surface 6b of the support substrate 6 when viewed from above. Figure 2 In the examples of , the light receiving portion or light emitting portion E1b is positioned to overlap with the exposed portion of the core 51 when viewed from above, and the light receiving portion or light emitting portion 1b is opposed to the upper surface 51a of the core 51 in the thickness direction (Z direction) of the wiring substrate 1. A portion of the light propagating from the core 51 toward the first end 5a leaks out from the upper surface 51a to the outside of the core 51 as evanescent light and is incident on the light receiving portion or light emitting portion E1b of the component E1. The upper surface 51a is opposed to the light receiving surface or light emitting surface E1c of the component E1 without passing through the covering portion 52, so it is considered that efficient optical coupling can be achieved. In addition, the optical waveguide in which the core 51 of the optical waveguide is exposed at the end of the optical waveguide and the component having a light receiving surface or light emitting surface formed on the side of the component can also be optically coupled by end face connection.

[0057] Figure 2 The through conductor 61 shown has a connection portion 61a connected to the electrode E1a of the component E1 on the first surface 6b side of the support substrate 6. It should be noted that the "connection" in "the connection portion connected to the electrode E1a of the component E1" refers to connection only via a connection body such as a solder such as a conductive bump 63, a connection material such as an adhesive (not via other structural elements that do not have a connection function), or direct connection without any component at all. And, Figure 2The through conductor 61 of the example is connected to the conductor pad 11a of the conductor layer 11 via the conductive connection body 4 on the second surface 6a side of the support substrate 6. The electrical signal generated by photoelectric conversion in the component E1 is output from the electrode E1a to the conductor pad 11a via the through conductor 61, and is input to the component E2 through the conductor layer 11 (see Figure 1 On the other hand, the electrical signal output from the component E2 to the component E1 is input to the electrode E1a via the conductor pad 11a and the through conductor 61, and is converted into an optical signal in the component E1.

[0058] In the wiring substrate 1 of the present embodiment, the support substrate 6 having the optical waveguide 5 formed on the first surface 6b includes a component E1 optically coupled to the optical waveguide 5 and a through conductor 61 that can be connected on the first surface 6b side, for example, at a connection portion 61a. The through conductor 61 that penetrates the support substrate 6 can be connected on the second surface 6a side, for example, as shown in FIG. Figure 2 In this way, the component E1 is directly connected to the conductor layer 11 of the electric wiring portion 2, or is connected to the conductor layer 11 via an arbitrary conductor (not shown) extending along the second surface 6a. That is, the component E1 and the electric wiring portion 2 can be connected via the through conductor 61 of the support substrate 6. Through the support substrate 6, more specifically, through the through conductor 61, the electrode E1a of the component E1 and the conductor of the electric wiring portion 2 can be electrically and mechanically connected.

[0059] Thus, in the wiring substrate 1 of the present embodiment, the through conductor 61 exposed on the first surface 6b side of the support substrate 6 and electrically and mechanically connected to the component E1 is included in the conductor area CA of the support substrate 6. In addition, the optical waveguide 5 including the core 51 optically coupled to the component E1 is also formed on the first surface 6b. Therefore, the portion (at the end of the wiring substrate 1) connected to the electrode E1a of the component E1 is Figure 3 The connecting portion 61a of the through conductor 61 in the example is easily positioned at a predetermined relative position corresponding to the positional relationship between the electrode E1a and the light receiving portion or the light emitting portion E1b (the relative position of the portion of the core 51 connected to the electrode E1a relative to the portion optically coupled to the light receiving portion or the light emitting portion E1b is also referred to as the "relative position" hereinafter). The predetermined relative position is a position that realizes appropriate optical coupling between the component E1 and the core 51 and reliable connection between the component E1 and the conductor layer 11.

[0060] That is, when the optical waveguide 5 is arranged on the supporting substrate 6, in order to connect the electrode E1a to the conductor layer 11 without passing through the supporting substrate 6, it is necessary to provide a conductor such as a conductor post (not shown) between the conductor layer 11 and the electrode E1a. Moreover, in order to achieve a predetermined relative position relative to the core 51, such a conductor is required to have an appropriate height determined according to the height of the core 51 from the surface 2a of the electric wiring portion 2. However, since the connecting material 7, the supporting substrate 6, and the lower coating layer 521 of the coating 52 are interposed between the electric wiring portion 2 and the core 51, the required height is easily changed, and therefore, it is sometimes difficult to provide a conductor having the required height on the conductor layer 11.

[0061] In addition, since the thermal expansion coefficient of such a conductor is often different from that of the support substrate 6 and the covering portion 52, the height of the conductor relative to the core portion 51 is easily changed according to changes in the ambient temperature. Such changes in the relative position of the conductor relative to the core portion 51 caused by thermal expansion occur not only in the Z direction but also in the direction along the surface of the support substrate 6. If the relative position relative to the core portion 51 is offset from the prescribed relative position, the conductor layer 11 and the electrode E1a of the component E1 may not be properly electrically connected or mechanically connected, or the core portion 51 and the light receiving portion or light emitting portion E1b of the component E1 may not be properly optically coupled.

[0062] However, in the present embodiment, the conductor region CA of the support substrate 6 includes the through conductor 61 exposed on the first surface 6b side of the support substrate 6. Figure 2 In the example of , the through conductor 61 has a connection portion 61a electrically and mechanically connected to the electrode E1a of the component E1 on the first surface 6b side. Only the lower coating layer 521 of the coating portion 52 exists between the first surface 6b of the support substrate 6 and the core 51. Therefore, the portion connected to the electrode E1a, such as the connection portion 61a, in the through conductor 61 is easily positioned at a predetermined relative position relative to the core 51. In addition, it is considered that the portion connected to the electrode E1a, such as the connection portion 61a, and the core 51 are displaced in conjunction with each other in any direction of the thickness direction of the support substrate 6 and the direction along the surface of the support substrate 6 according to the expansion or contraction of the support substrate 6 even if the ambient temperature changes. Therefore, the relative position of the portion connected to the electrode E1a, such as the connection portion 61a, with respect to the core 51 is difficult to change. In addition, the through conductor 61 penetrates the support substrate 6, so it can be connected to the conductor included in the electric wiring portion 2, such as the conductor layer 11, on the second surface 6a side. That is, according to the present embodiment, it is considered possible to realize both appropriate optical coupling between an optical component such as the component E1 mounted on a wiring board and a core portion, and reliable electrical and mechanical connection between the optical component and a conductor in an electrical wiring portion.

[0063] In addition, according to the present embodiment, compared with the case where the electrode E1a is connected to the conductor layer 11 using a conductor such as a conductor post without passing through the support substrate 6, it is not necessary to arrange the component E1 on a high conductor, so it is considered that the component E1 can be easily mounted. In addition, according to the present embodiment, compared with the case where the support substrate 6 is also not connected to the conductor layer 11 via a conductor such as a conductor post but only via a connector such as solder, it is sometimes possible to connect the connection pad (at the bottom of the support substrate 6) to the component E1. Figure 3 In the example, the connecting portion 61a of the through conductor 61 is miniaturized. That is, in order to connect the component E1 and the conductor layer 11 using only a connector such as solder, a connector with a height equivalent to the thickness of the lower cladding layer 521 of the cladding portion 52 of the support substrate 6 and the optical waveguide 5 is required, and the connector occupies an area that increases as the height increases when viewed from above. Therefore, the miniaturization of the connection pad is sometimes hindered. In the present embodiment, since the through conductor 61 exposed on the first surface 6b side of the support substrate 6 is provided, the distance between the electrode E1a of the component E1 and the portion connected to the electrode E1a, such as the connecting portion 61a, is short, and the connector required for connecting the two (for example, Figure 2 The height of the conductive bump 63 shown in FIG. 6 is reduced. Therefore, it becomes easy to miniaturize the connection pads such as the connection portion 61a to the component E1.

[0064] like Figure 2 As shown in FIG. 1 , the through conductor 61 is formed in the through hole 60 penetrating the support substrate 6. Figure 1 In the figure, it is shown as a monomer, but it can also be shown as an enlarged Figure 2 As shown in the figure, a multi-layer structure is provided. Figure 2 In the example of FIG. 6 , the through conductor 61 is composed of a metal film 611 and a metal column 612. Figure 2 The metal film 611 and the metal pillar 612 shown as the material of the through-conductor 61 are formed of any metal such as copper or nickel. The metal film 611 is formed on the inner wall surface of the support substrate 6 exposed in the through-hole 60 and around the through-hole 60 in the first surface 6b and the second surface 6a of the support substrate 6. The metal film 611 can be formed by chemical plating or sputtering, for example. The metal pillar 612 is formed on the metal film 611. The inside of the through-hole 60 is mainly filled with the metal pillar 612. The metal pillar 612 can also be formed by a plated film formed by electroplating using the metal film 611 as a power supply layer, for example.

[0065] The connection portion 61a of the through conductor 61 is provided on the first surface 6b of the support substrate 6 so as to overlap with the through hole 60 in a plan view. The through conductor 61 also has a connection portion 61b connected to the conductor layer 11 on the second surface 6a side. The connection portion 61b is provided on the second surface 6a of the support substrate 6 so as to overlap with the through hole 60 in a plan view. The through conductor 61 protrudes from the first surface 6b of the support substrate 6 at the connection portion 61a, and protrudes from the second surface 6a at the connection portion 61b. The connection portion 61a and the connection portion 61b are wider than the portion of the through conductor 61 in the through hole 60 in a plan view, and the connection portion 61a covers a portion of the first surface 6b, and the connection portion 61b covers a portion of the second surface 6a.

[0066] The through conductor 61 includes a metal film 61c, which constitutes the surface of the through conductor 61 on the first surface 6b side along the first surface 6b of the support substrate 6. Similarly, the through conductor 61 includes a metal film 61d constituting the surface on the second surface 6a side of the support substrate 6. The metal films 61c and 61d may be, for example, chemically plated films or sputtered films containing nickel, palladium, gold, etc. The metal films 61c and 61d may sometimes prevent corrosion of the surfaces of the connecting portion 61a and the connecting portion 61b. In addition, the metal films 61c and 61d may sometimes prevent the metal components constituting the conductive connecting body 4 and the conductive bump 63 from diffusing into the connecting portions 61a and 61b.

[0067] Figure 2 The support substrate 6 shown includes a conductive bump 63 formed on the through conductor 61 on the first surface 6b side. The conductive bump 63 is formed using, for example, a tin-based solder, a gold-based solder, or the like. In addition, the conductive bump 63 may include a metal such as tin, silver, copper, bismuth, zinc, gold, and antimony alone or in combination. The electrode E1a of the component E1 is electrically and mechanically connected to the connecting portion 61a by the conductive bump 63 that melts when the component E1 is mounted. Figure 2 In the example of FIG. 1 , the connection portion 61 a is connected to the electrode E1 a only via the conductive bump 63 as a connection body.

[0068] In addition, although Figure 2 Although not shown in the figure, the support substrate 6 may also have a conductive metal that facilitates connection with the electric wiring portion 2 on the surface of the through conductor 61 on the electric wiring portion 2 side before being arranged on the electric wiring portion 2. Such a conductive metal (for example Fig.7D The conductive bump 631 shown in the figure may be formed of the same material as the conductive bump 63 on the first surface 6b side, or may be formed of a material different from that of the conductive bump 63.

[0069] The conductive bump 63 preferably has an appropriate height such that the conductive bump 63 contacts the electrode E1a of the component E1 when the component E1 is mounted, and the core 51 of the optical waveguide 5 and the light receiving portion or light emitting portion E1b of the component E1 can be optically coupled appropriately. For example, the height of the conductive bump 63 on the first surface 6b of the support substrate 6 (the height of the conductive bump 63 from the first surface 6b) is preferably equal to the height of the lower cladding layer 521 of the cladding portion 52 on the first surface 6b (the height of the lower cladding layer 521 from the first surface 6b). Specifically, the height of the conductive bump 63 on the first surface 6b is not particularly limited, but is preferably not less than 50% and not more than 150% of the height of the lower cladding layer 521 on the first surface 6b. It is considered that when the conductive bump 63 has such a height, the electrode E1a of the component E1 and the through conductor 61 are reliably connected, and the light receiving portion or light emitting portion E1b of the component E1 and the core 51 of the optical waveguide 5 are optically coupled with sufficient coupling efficiency.

[0070] Figure 2 The through conductor 61 in the conductor wiring portion 2 is connected to the conductor pad 11a as a conductor in the electric wiring portion 2 via the conductive connection body 4. As an example of the conductive connection body 4, there is a conductive bump 25 (see Figure 1 ) Similarly, the bumps formed of conductive metal formed on the conductor pads 11a can be formed of various solders, low melting point metals, etc. That is, the conductive connector 4 can also be a metal body such as a resolidified body such as tin-based solder, gold-based solder, or low melting point metal supplied to the conductor pads 11a and melted by heating during connection of the optical wiring section 3. Sometimes, the formation of the conductive bumps 25 and the supply of the conductive connector 4 are performed simultaneously, and the efficiency of manufacturing the wiring substrate 1 is improved.

[0071] Alternatively, the conductive connection body 4 may be a bump (for example, a bump made of a conductive metal) provided on the through conductor 61 on the second surface 6a side of the support substrate 6. Fig.7D The conductive bump 631 shown in the figure may be a solidified body after melting various solders such as tin-based, gold-based, etc., or a metal body of a low melting point metal. The conductive metal bump may also be formed of the same material as the conductive bump 63 formed on the first surface 6b side. Therefore, the conductive connector 4 that connects the conductor in the electrical wiring portion 2 such as the through conductor 61 and the conductor pad 11a may also be composed of the same material as the conductive bump 63 of the optical wiring portion 3. If the conductive bump 63 and the supply of metal such as solder to the conductive connector 4 on the side of the optical wiring portion 3 are performed simultaneously (the bump is formed by the conductive metal on the connection portion 61b), the efficiency of manufacturing the wiring substrate 1 is improved. The conductive connector 4 may also be a solidified body of a mixture of a bump formed of a conductive metal provided on the connection portion 61b of the through conductor 61 and a connector such as solder supplied to the conductor pad 11a in the form of a bump when they are melted.

[0072] However, the conductive connector 4 may be made of a material having a different composition and composition ratio from the material constituting the conductive bump 63 and the conductive bump 25. For example, if the conductive connector 4 has a higher melting point than the conductive bump 63 and the conductive bump 25, then the conductive connector 4 may be made of a material having a different composition and composition ratio from the material constituting the conductive bump 63 and the conductive bump 25. Figure 1 ) during installation, the conductive connecting body 4 will not remelt, thereby sometimes preventing the strength of the conductive connecting body 4 from being reduced due to remelting.

[0073] exist Figure 2 In the example, the optical wiring portion 3 is fixed to the electric wiring portion 2 using a connecting material 7. Specifically, the second surface 6a of the support substrate 6 and the one surface 2a of the electric wiring portion 2 are connected by the connecting material 7. The material constituting the connecting material 7 is not particularly limited, but an insulating material is preferably used, and a resin material is more preferably used. As an example, a thermosetting resin can be mentioned. The material constituting the connecting material 7 can use any insulating adhesive such as an epoxy-based adhesive or an acrylic-based adhesive. In addition, the connecting material 7 is preferably a material different from the material of the conductive connector 4. When the connecting material 7 is different from the conductive connector 4 and has insulating properties, such as Figure 3 As shown, when the support substrate 6 includes a plurality of through conductors 61, it is considered that short circuits between adjacent through conductors 61 can be prevented. In addition, if the connection material 7 has a lower elastic modulus than the conductive connection body 4, which is a metal such as solder, for example, the stress generated in the support substrate 6 and the electric wiring portion 2 (specifically, the solder resist 23) connected by the connection material 7 over a relatively wide range is estimated to be small, for example, due to the difference in thermal expansion coefficient.

[0074] When the material constituting the connection material 7 is a resin material, the glass transition temperature of the connection material 7 is preferably 50° C. to 200° C. The thermal expansion coefficient of the connection material 7 is, for example, 30 ppm / ° C. to 200 ppm / ° C. The thickness of the connection material 7 is not particularly limited, but is about 5 μm to 200 μm.

[0075] The connecting material 7 may contain particles in the material, specifically, inorganic particles, metal particles, resin particles, etc. The size of the particles contained in the connecting material 7 is not particularly limited, and is, for example, about 0.1 μm or more and 20 μm or less. By containing particles in the connecting material 7, the rigidity of the connecting material 7 is improved, or heat resistance is imparted to the connecting material 7.

[0076] like Figure 3 As shown, in Figure 1 to Figure 3 In the example of FIG. 5 , the optical waveguide 5 includes a plurality of cores 51. In addition, each core 51 is covered by a cladding 52 when viewed from above, but Figure 3In FIG. 5 , each core 51 is depicted with a solid line for easy viewing. The plurality of cores 51 are arranged in parallel in a direction intersecting the propagation direction (X direction) of light in the core 51. Figure 3 In the example of FIG. 5 , the spacing between the plurality of cores 51 increases as the distance from the first end 5a to the second end 5b increases. Therefore, the spacing between the cores 51 at the second end 5b is larger than that at the first end 5a. For example, the plurality of optical fibers optically coupled to the cores 51 at the second end 5b may not be arranged in the same manner as the plurality of light receiving portions or light emitting portions E1b (see FIG. 5 ) of the component E1. Figure 2 ) are arranged with a pitch as small as the configuration pitch of the Figure 3 In the example, the plurality of cores 51 are arranged at a larger pitch in the second end 5b than in the first end 5a. Therefore, it is considered that the cores 51 and the component E1 (see Figure 2 ) or optical fibers are properly optically coupled without the need for additional spacing conversion units.

[0077] exist Figure 3 In the example of FIG. 1 , the conductor region CA of the support substrate 6 includes a plurality of through conductors 61. The plurality of through conductors 61 are arranged in a row along a direction substantially perpendicular to the X direction. In each of the plurality of through conductors 61, the connection portion 61a covers the through hole 60 formed by the through conductor 61. The plurality of through conductors 61 are all provided in a region (conductor region CA) other than the non-conductor region NC where the optical waveguide 5 is formed on the first surface 6b of the support substrate 6 when viewed from above. Therefore, the connection portion 61a of the through conductor 61 can be connected to the component E1 (see FIG. 1 ) without interfering with the optical waveguide 5. Figure 2 )connect.

[0078] exist Figure 1 to Figure 3 In the example, Figure 2 as well as Figure 3 As shown, the entire component area A1 overlaps with the support substrate 6 when viewed from above. That is, the component area A1 does not overlap with the area of ​​the surface 2a of the electric wiring portion 2 that is not covered by the support substrate 6. The area of ​​the surface 2a that is not covered by the support substrate 6 does not have a conductor pad directly connected to the component E1. On the other hand, the plurality of through conductors 61 and their connecting portions 61a are all located in the component area A1 when viewed from above. Preferably, in the wiring substrate 1, all the conductor pads directly connected to the plurality of electrodes E1a of the component E1 are provided on the support substrate 6 as the connecting portions 61a of the through conductors 61. In this way, if all the conductor pads connected to the component E1 are provided on the support substrate 6, it is considered that all the electrodes E1a of the component E1 are easily and appropriately connected electrically and mechanically to the conductors in the electric wiring portion 2.

[0079] exist Figure 4A to Figure 4DIn FIG. 1 , an optical wiring portion 3α as another example of an optical wiring portion in a wiring substrate according to an embodiment is shown in a state of being connected to the surface 2a of the electric wiring portion 2. Figure 5 Shown in Figure 4A An example of a plan view of the optical wiring portion 3α. Figure 4A to Figure 4D as well as Figure 5 The optical wiring portion 3α of the example Figure 1 The supporting substrate 6 of the optical wiring section 3 of the example of , etc. similarly includes a supporting substrate 6α having a through conductor 61. Figure 4A to Figure 4D and Figure 5 The support substrate 6α of the example further includes a solder resist 64 on the first surface 6b and the second surface 6a. The solder resist 64 is formed around the through conductor 61 on the first surface 6b and the second surface 6a, respectively.

[0080] The solder resist 64 is formed of any insulating resin. The solder resist 64 can be formed of, for example, the same material as the material constituting the solder resist 23 included in the electrical wiring portion 2, such as a photosensitive epoxy resin, a polyimide resin, etc. If the solder resist 64 is formed around the through conductor 61, it is considered that short circuit failures caused by the conductive bumps 63 and the conductive connectors 4 between each of the plurality of through conductors 61 can be prevented. In addition, the solder resist 64 can also be formed only on any of the first surface 6b and the second surface 6a. It is considered that at least any short circuit failures in the first surface 6b and the second surface 6a can be prevented.

[0081] exist Figure 4A In the example of FIG. 1 , the connection material 7 connecting the electric wiring portion 2 and the support substrate 6α is arranged so that the outer edge of the electric wiring portion 2 and the outer edge of the connection material 7 are aligned near the end of the electric wiring portion 2. That is, the connection material 7 is arranged so that the end face 2b of the electric wiring portion 2 and the end face 71 of the connection material 7 are substantially flush with each other. The connection material 7 may also be arranged as Figure 4A As in the example of FIG.

[0082] exist Figure 4B In the example, the connection material 7 is arranged inside the outer edge of the wiring substrate 1 so that the end surface 71 is located inside the outer edge of the electric wiring portion 2 . Figure 4B In the example, the end surface 71 of the connection material 7 is recessed toward the inner side of the electric wiring portion 2 from the end surface of the electric wiring portion 2. In addition, the distance between the end surface 71 of the connection material 7 and the end of the electric wiring portion 2 is preferably within 10 mm.

[0083] The connecting material 7 can also be Figure 4C and Figure 4D As in the example of FIG. 1 , the wiring board 1 extends from the end of the wiring board 1 and is hung on the support board 6α outside the electric wiring part 2. Figure 4CIn the example of FIG. 1 , the connection material 7 extends from the outer edge of the electric wiring portion 2 and hangs on the portion of the optical wiring portion 3α that protrudes from the outer edge of the electric wiring portion 2. The connection material 7 covers the portion of the electric wiring portion 2 protruding from the outer edge of the electric wiring portion 2 in the second surface 6a of the support substrate 6α. Therefore, it is considered that the support substrate 6α and the optical waveguide 5 are more firmly connected to the electric wiring portion 2. In addition, the distance that the connection material 7 protrudes from the outer edge of the electric wiring portion 2 is preferably within 10 mm.

[0084] exist Figure 4D In the example of FIG. 1 , the connection material 7 is hung on both the support substrate 6α and the end surface of the wiring substrate 1 outside the electric wiring portion 2. That is, Figure 4D The connection material 7 is hung not only on the support substrate 6α but also on the end surface 2b of the electric wiring portion 2 on the outside of the electric wiring portion 2. The connection material 7 covers the protruding portion of the second surface 6a of the support substrate 6α protruding from the outer edge of the electric wiring portion 2 and a part of the end surface 2b of the electric wiring portion 2 at the end of the wiring substrate 1. Therefore, it is considered that the optical wiring portion 3α including the support substrate 6α and the optical waveguide 5 is further firmly connected to the electric wiring portion 2. In addition, in the previously referenced Figure 1 to Figure 3 In the wiring substrate 1 having the supporting substrate 6 without the solder resist as shown in the example, Figure 4A to Figure 4D The connection material 7 is arranged in any of the illustrated forms.

[0085] Figure 4A to Figure 4D as well as Figure 5 The illustrated support substrate 6α and Figure 3 The illustrated support substrate 6 similarly includes a plurality of through-conductors 61. In the support substrate 6α, the plurality of through-conductors 61 are arranged in a zigzag pattern in a predetermined direction in a plan view. Figure 5 The plurality of through conductors 61 shown as an example are arranged in a zigzag or staggered arrangement in the Y direction which is substantially perpendicular to the X direction, which is the propagation direction of light propagating in the core 51. That is, the plurality of through conductors 61 arranged in the Y direction are arranged in a row every other one, and are arranged over two adjacent rows in the X direction. The through conductors closest to each other in the Y direction are arranged in different rows. When the plurality of through conductors 61 are arranged in a zigzag or staggered arrangement, the optical path length in a specific direction (in the X direction) can be reduced. Figure 5 In the example of the through conductor 61 in the Y direction), more through conductors 61 can be arranged to suppress the possibility of short circuits between each other. In addition, the plurality of through conductors 61 may be arranged in a grid arrangement (see Figure 8B ). Among the plurality of through conductors 61, the intervals between the through conductors 61 may be fixed or not fixed, or some of the through conductors may be fixed and the rest of the through conductors may be not fixed. The through conductors 61 can be arranged arbitrarily.

[0086] In addition, Figure 5 In the example of Figure 5 The through conductor 61 at the lower end of the through conductor 61 has its connection portion 61a at a position that does not overlap with the through hole 60. That is, the connection portion 61a of the through conductor 61 at the lower end is provided at a position that is offset from the through hole 60 in a plan view. If the connection portion 61a is provided in this way, the conductor pad 11a (see Figure 4A ) is arranged relative to the electrode E1a of the component E1 mounted on the wiring substrate 1 (see Figure 4A ) configuration freedom is improved.

[0087] In addition, Figure 5 In the example of FIG. 5 , the width of each of the plurality of cores 51 increases as the width approaches the second end 5b from the first end 5a. Therefore, the width of the core 51 at the second end 5b is larger than the width of the first end 5a. The width of the plurality of optical fibers optically coupled to the core 51 at the second end 5b may be larger than the width of the plurality of light receiving portions or light emitting portions E1b (see FIG. 5 ) of the component E1. Figure 4A ) is large. Figure 5 In the example, each core 51 has a larger width at the second end 5b than at the first end 5a, so it is considered that the core 51 is optically coupled appropriately with the component E1 or the optical fiber with less light loss at each of the first end 5a and the second end 5b.

[0088] In addition, the core 51 of the optical waveguide 5 included in the wiring substrate of the embodiment may have a thickness increasing from the first end 5a to the second end 5b in addition to the width increasing from the first end 5a to the second end 5b.

[0089] exist Figure 6 , a through conductor 61α as another example of a through conductor in the wiring substrate of the embodiment is shown together with the support substrate 6 and the connection material 7. The through conductor 61α does not include Figure 2 The through conductor 61 shown in the example includes a metal film 611 and a metal column 612. The through conductor 61α is composed of a single element. For example, the through conductor 61α may be a cured body of a conductive paste composed of epoxy resin containing conductive particles such as silver and copper. Figure 6 The through conductor 61α of the example does not protrude from the first surface 6b and the second surface 6a of the support substrate 6. The two end surfaces of the through conductor 61α intersecting the Z direction are substantially coplanar with the first surface 6b or the second surface 6a. The end surface of the through conductor 61α on the first surface 6b side of the support substrate 6 is used as the component E1 (refer to Figure 1) functions as a connecting portion 61αa connected to the first surface 6b. A conductive bump 63 is provided on the end surface on the first surface 6b side. On the other hand, the end surface on the second surface 6a side of the through conductor 61α is connected to the conductor layer 11 via the conductive connector 4. Figure 6 As in the example of the embodiment, the through conductor included in the substrate included in the optical wiring portion in the wiring substrate of the embodiment may not protrude from both surfaces of the substrate. Furthermore, the connection portion of the through conductor connected to the component optically coupled to the optical waveguide may be composed of the end face of the through conductor that is substantially coplanar with the surface of the substrate.

[0090] Next, refer to Figure 7A to Figure 7G , use manufacturing Figure 1 An example of a method for manufacturing a wiring substrate according to an embodiment will be described by taking the case of the wiring substrate 1 of FIG.

[0091] like Fig. 7A As shown, a semiconductor substrate such as a glass plate, a ceramic plate or silicon is prepared as a support substrate 6. For example, a support substrate 6 having a thickness of about 0.05 mm to 0.7 mm is prepared. Then, a hole is formed in the support substrate 6 by drilling, laser processing or etching. The diameter of the hole formed in the support substrate 6 is not particularly limited, and a through hole 60 having a hole diameter of about 0.05 mm to 0.2 mm is formed.

[0092] like Figure 7B As shown in FIG. 1 , a through-conductor 61 is formed in the through-hole 60 of the support substrate 6. Figure 7B In the example, a through conductor 61 is formed which also has a connecting portion 61a and a connecting portion 61b. As an example, the through conductor 61 is formed by forming a metal film on the wall surface in the through hole 60 and the entire surface of the first surface 6b and the second surface 6a of the support substrate 6 by chemical plating or the like, and forming a plated film by electroplating using the metal film as a power supply layer. The unnecessary metal film and the plated film on the surface of the support substrate 6 are removed by, for example, wet etching. The connecting portion 61a is formed by the metal film and the plated film remaining on the first surface 6b of the support substrate 6. In addition, although in Figure 7B Not shown, but in the through conductor 61 Figure 2 In the case where the metal films 61c and 61d are included as in the example of FIG, the metal films 61c and 61d are formed by chemical plating or sputtering of nickel, palladium, gold, etc. In addition, the through conductor in the wiring substrate of the embodiment can also be formed by filling the through hole 60 with a conductive paste composed of epoxy resin or the like containing conductive particles such as silver and curing it. In this case, it is possible to form Figure 6 The through conductor 61α of the example shown.

[0093] like Figure 7CAs shown, an optical waveguide 5 is formed on the first surface 6b of the supporting substrate 6. Specifically, first, a lower cladding layer 521 of the cladding portion 52 is formed. The constituent material of the cladding portion 52, such as a resin such as PMMA, is formed into a film shape and is thermally pressed onto the supporting substrate 6. Furthermore, a core portion 51 is formed on the lower cladding layer 521. The core portion 51 is formed using, for example, a resin material such as PMMA as the constituent material of the core portion 51. For example, the constituent material of the core portion 51 is formed into a film shape and is thermally pressed onto the entire surface of the lower cladding layer 521, and is patterned into the desired shape and number of cores 51 by photolithography. In addition, the lower cladding layer 521 may be formed by spin coating a resin material instead of a film.

[0094] In addition, the upper cladding layer 522 is formed on the lower cladding layer 521 and the core 51. For example, similarly to the formation of the lower cladding layer 521, the constituent material of the upper cladding layer 522, such as PMMA, is formed into a film and thermally pressed to the lower cladding layer 521 and the core 51. As a result, the cladding portion 52 composed of the lower cladding layer 521 and the upper cladding layer 522 is formed. Thereafter, a portion of the first end portion 5a side of the core 51 in the upper cladding layer 522 is removed by photolithography. In addition, the upper cladding layer 522 may be formed by spin coating a resin material instead of a film. The optical waveguide 5 including the core 51 and the cladding portion 52 and with the portion on the first end portion 5a side of the core 51 exposed is completed on the supporting substrate 6. In addition, the optical waveguide 5 may be formed by other optical waveguide forming methods such as imprinting method, photobleaching method, etc. instead of using such a photolithography method.

[0095] like Fig.7D As shown in FIG. 1 , a conductive bump 63 is formed on the surface of the through conductor 61. Fig.7D In the example, a conductive bump 631 is formed on the surface of the connecting portion 61b. The conductive bumps 63, 631 are formed, for example, by supplying solder balls or solder paste such as tin-based solder or gold-based solder, and then solidifying them after melting by heating. The conductive bumps 63, 631 are not limited to this method, and can also be formed by chemical plating, etc., and can be formed by any method. For example, a conductive bump 63 having a height from the first surface 6b that is equal to or less than the height of the lower cladding layer 521 of the cladding portion 52 from the first surface 6b of the supporting substrate 6, specifically, is formed that is greater than 50% and less than 100% of the height of the lower cladding layer 521. After the above steps, the optical wiring portion 3 is completed.

[0096] like Fig. 7E As shown, the connection material layer 7a is formed on the second surface 6a of the support substrate 6. The connection material layer 7a is supplied to the second surface 6a so as to fix the support substrate 6 to the electric wiring portion 2 (see Figure 1 ) of the connecting material 7 (refer to Figure 1For example, the connection material 7 formed into a film shape is stacked on the second surface 6a. The connection material layer 7a is formed of any insulating adhesive such as epoxy-based, acrylic-based, etc.

[0097] The connector C is provided so that the upper housing C1 and the lower housing C2 sandwich the optical waveguide 5 and the support substrate 6 as required. For example, the upper housing C1 is attached to the optical waveguide 5, the lower housing C2 is attached to the support substrate 6, and the upper housing C1 and the lower housing C2 are fitted together.

[0098] like Figure 7F As shown, the electric wiring portion 2 is prepared. As an example, the electric wiring portion 2 is prepared using a general method for forming a build-up wiring substrate including a core substrate. For example, the core substrate 30 is formed by forming a through-hole conductor 33 on a copper-clad laminate on both sides including an insulating layer 32 or forming a conductor layer 31 by a subtractive method. Then, insulating resin films are thermally pressed onto both sides of the core substrate 30, and a conductor layer is formed by a semi-additive method, thereby forming insulating layers 21, 22 and conductor layers 11, 12 and via conductors 26. Furthermore, solder resists 23, 24 are formed by laminating epoxy resins or polyimide resins or coating based on these resins, and openings 23a, 24a are formed by, for example, photolithography. And, in the opening 23a, a conductive bump 25 is formed by arranging tin-based solder balls and reflowing the solder balls.

[0099] Moreover, if Figure 7F As shown in FIG. 1 , the optical wiring section 3 is arranged on the electrical wiring section 2. The optical wiring section 3 is aligned in such a manner that the through conductor 61 is placed on the conductive bump 25 on the conductor pad 11a of the conductor layer 11. Then, the optical wiring section 3 and the electrical wiring section 2 are connected by, for example, a heat treatment. For example, by a reflow treatment, the conductive bump 25 on the conductor pad 11a and the conductive bump 631 of the support substrate 6 are fused to form a conductive connection body 4 (see FIG. 1 ). Figure 1 ) and then solidifies, connecting the through conductor 61 to the conductor pad 11a. On the other hand, the connection material layer 7a is also softened by heating, connecting the solder resist 23 to the support substrate 6.

[0100] Furthermore, the formation of the connection material layer 7a before the optical wiring portion 3 and the electric wiring portion 2 are connected may be omitted. That is, in the state without the connection material layer 7a, first, for example, only the through conductor 61 and the conductor pad 11a may be connected by reflow treatment. Then, the connection material 7a may be injected into the gap between the electric wiring portion 2 and the optical wiring portion 3 (see Figure 1 ) and curing treatment based on heating, etc., the support substrate 6 and the solder resist 23 are bonded. After the above steps, the Figure 1 A wiring substrate 1.

[0101] When using the wiring substrate 1, Figure 7G As shown, a component E1 including an optical element is mounted. A component E2 may be mounted together with the component E1. The electrode E1a of the component E1 is connected to the connection portion 61a of the through conductor 61 via a conductive bump 63 that is melted during mounting. On the other hand, the light receiving portion or light emitting portion E1b of the component E1 is optically coupled to the exposed portion of the core 51 of the optical waveguide 5. According to this embodiment, it is considered that both appropriate optical coupling between the component E1 and the core 51 and reliable electrical and mechanical connection between the component E1 and the conductor pad 11a can be achieved.

[0102] Fig. 8A A wiring substrate 1β is shown as a modified example of the wiring substrate of the embodiment. The wiring substrate 1β includes Figure 1 The optical wiring portion 3β includes an optical wiring portion 3 having a structure similar to the optical wiring portion 3 included in the wiring substrate 1 of the embodiment of the present invention. The optical waveguide 5 included in the optical wiring portion 3β is Figure 1 The optical waveguide 5 exemplified in the above is different in that the core 51 is not exposed from the cladding 52 on the lower cladding layer 521 at the first end 5 a . Fig. 8A The core 51 of the example is also covered by the upper cladding layer 522 at the first end 5a, and only its end face is exposed together with the end face of the cladding 52 at the side 50 of the optical waveguide 5. The end face of the core 51 exposed at the side 50 is positioned to be opposite to the light receiving surface or light emitting surface E1c of the component E1 optically coupled with the core 51. The component E1 is arranged on the extension line from the first end 5a of the optical waveguide 5. Therefore, the component area A1 is located on the side of the optical waveguide 5 and does not overlap with any part of the optical waveguide 5 when viewed from above. The end face of the core 51 exposed at the side 50 of the optical waveguide 5 faces the component area A1, and is optically coupled with the light receiving surface or light emitting surface E1c of the component E1 through butt coupling.

[0103] Fig. 8A The optical wiring section 3β of the example includes a support substrate 6β and Figure 5 The supporting substrate 6α of the example of FIG. 1 similarly includes a plurality of through conductors 61. Figure 8B As shown, the plurality of through conductors 61 included in the support substrate 6β are arranged in a lattice (or grid or matrix) and each has a connection portion 61a with the component E1. Sometimes more electrodes E1a of the component E1 can be connected to the conductors in the wiring substrate 1β in a limited area. Fig. 8A The wiring substrate 1β shown in the figure has the same Figure 1 The wiring substrate 1 of the example of FIG. 1 is substantially similar in structure and is composed of substantially similar components. Figure 1 The same structural elements as those contained in Fig. 8A Mark or appropriately omit Figure 1 The same reference numerals are used to denote the same reference numerals, and duplicate descriptions are omitted.

[0104] The wiring substrate of the embodiment is not limited to the structures, shapes and materials illustrated in the drawings and in this specification. The wiring substrate of the embodiment, especially the electrical wiring portion, has an arbitrary stacking structure. For example, the electrical wiring portion may be a coreless substrate that does not include a core substrate and includes an arbitrary number of conductor layers and insulating layers. The conductor pad 11b may not be formed.

[0105] Description of symbols

[0106] 1, 1β: wiring substrate; 2: electric wiring portion; 2a: one surface of the electric wiring portion; 3, 3α, 3β: optical wiring portion; 11, 12, 31: conductor layer; 21, 22, 32: insulating layer; 4: conductive connector; 5: optical waveguide; 51: core; 52: cladding; 521: lower cladding; 522: upper cladding; 6, 6α, 6β: supporting substrate; 6a: second surface; 6b: first surface; 61, 61α: through conductor; 61a, 61αa: connecting portion; 61c, 61d: metal film; 63, 631: conductive bump; 64: solder resist; 7: connecting material; A1: component area; CA: conductor area; E1, E2: component; E1a, E2a: electrode; NC: non-conductor area.

Claims

1. A wiring substrate, comprising: an electric wiring portion including an insulating layer and a conductor layer; an optical wiring portion placed on one surface of the electrical wiring portion; and a component area capable of arranging components on the optical wiring portion, in, The optical wiring section includes: an optical waveguide comprising a core and a cladding; and a support substrate including a conductor region having a conductor and a non-conductor region, the support substrate having a first surface on a side where the component is arranged and a second surface on a side of the electric wiring portion, The support substrate has a thermal expansion coefficient lower than that of the optical waveguide, In the non-conductor region, the optical waveguide is formed on the first surface of the support substrate. The conductor region includes a through conductor that penetrates between the first surface of the support substrate and the second surface of the support substrate.

2. The wiring substrate according to claim 1, wherein: The through-conductor has a connection portion connected to the component, and the component is optically coupled to the core.

3. The wiring substrate according to claim 1, wherein The wiring substrate further includes a conductive bump formed on the through conductor.

4. The wiring substrate according to claim 3, wherein: The cladding portion includes a lower cladding layer constituting a portion closer to the support substrate than the core portion. The core is partially exposed from the cladding portion on the lower cladding layer, A height of the conductive bump on the first surface of the support substrate is less than or equal to a height of the lower cladding layer.

5. The wiring substrate according to claim 1, wherein The electric wiring portion has a conductor exposed on the one surface, The through conductor is connected to the conductor.

6. The wiring substrate according to claim 5, wherein: The wiring substrate further includes a conductive bump formed on the through conductor. The through conductor and the conductor are connected via a conductive connection body made of the same material as the conductive bump.

7. The wiring substrate according to claim 5, wherein: The through conductor is connected to the conductor via a conductive connection body, The second surface of the support substrate and the one surface of the electric wiring portion are connected via a connection material made of a material different from that of the conductive connection body.

8. The wiring substrate according to claim 1, wherein The entire component region overlaps with the support substrate in a plan view.

9. The wiring substrate according to claim 1, wherein: The through conductor includes a metal film, and the metal film constitutes a surface of the through conductor along the first surface of the support substrate.

10. The wiring substrate according to claim 1, wherein The support substrate includes a solder resist formed around the through conductor on at least one of the first surface and the second surface.

11. The wiring substrate according to claim 1, wherein The conductor region includes a plurality of through conductors. The plurality of through conductors are arranged in a zigzag pattern in a predetermined direction in a plan view.

12. The wiring substrate according to claim 5, wherein: The support substrate and the electric wiring portion are connected by a connecting material, The connection material is arranged to reach an end portion of the wiring substrate.

13. The wiring substrate according to claim 5, wherein: The support substrate and the electric wiring portion are connected by a connecting material, The connection material is arranged to the inner side of the wiring substrate.

14. The wiring substrate according to claim 5, wherein: The support substrate and the electric wiring portion are connected by a connecting material, The connection material extends from an end portion of the wiring substrate and is hung on the support substrate.

15. The wiring substrate according to claim 5, wherein: The support substrate and the electric wiring portion are connected by a connecting material, The connection material extends from an end portion of the wiring substrate and is hung on the support substrate and the wiring substrate.

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