Composite wiring board, electronic module, and electronic device

Abstract

The present invention comprises an optical waveguide substrate, an external substrate, a conductive member, and an insulator. The optical waveguide substrate has a base, an optical waveguide, and an electrode. The base includes a first base surface. The optical waveguide is positioned on the first base surface and includes an opening in a first upper surface. The electrode extends from the inside of the opening to the outside of the opening. The external substrate has a wiring conductor on a first external substrate surface. The conductive member electrically connects the electrode and the wiring conductor. The insulator covers the conductive member from the first base surface side and from the first external substrate surface side. The height from the first base surface to the top of the insulator is greater than the height from the first base surface to the first upper surface.

Description

Composite Wiring Substrate, Electronic Module, and Electronic Device

[0001] The present disclosure relates to a composite wiring substrate, an electronic module, and an electronic device.

[0002] Conventionally, an optical waveguide disclosed in Patent Document 1 has been known as an optical waveguide substrate used for a light source module of an electronic device such as a head-mounted display. An external substrate such as a printed circuit board is connected to an electrode provided on the optical waveguide substrate.

[0003] Japanese Patent Application Laid-Open No. 2005-266657

[0004] The composite wiring substrate according to the present disclosure includes an optical waveguide substrate, an external substrate, a conductive member, and an insulator. The optical waveguide substrate has a substrate body, an optical waveguide, and an electrode. The substrate body includes a first substrate surface. The optical waveguide is located on the first substrate surface and includes an opening on a first upper surface. The electrode extends from the inside of the opening to the outside of the opening. The external substrate has a wiring conductor on a first external substrate surface. The conductive member electrically connects the electrode and the wiring conductor. The insulator covers the conductive member from the first substrate surface side and the first external substrate surface side. The height from the first substrate surface to the top of the insulator is higher than the height from the first substrate surface to the first upper surface.

[0005] The electronic module according to the present disclosure includes a composite wiring substrate, an electronic element electrically connected to the electrode, and a module lid covering the electronic element.

[0006] The electronic device according to the present disclosure includes an electronic module and a display unit. The electronic element is a light-emitting element, and the display unit performs display by the emitted light from the electronic module.

[0007] It is a perspective view showing a schematic configuration of a composite wiring substrate according to an embodiment of the present disclosure. It is a plan view showing a schematic configuration of the composite wiring substrate. It is a front view showing a schematic configuration of the composite wiring substrate. It is a perspective view showing an example of an electronic device according to an embodiment of the present disclosure.

[0008] Embodiments of the present disclosure will be described below with reference to the drawings. However, for the sake of clarity, the drawings below are simplified to show only the main components necessary to describe the embodiments. Therefore, embodiments of the present disclosure may include any components not shown in the drawings. Furthermore, the drawings do not necessarily accurately represent the dimensional ratios of the actual components.

[0009] Regarding direction, the direction in which the first substrate surface 11a of the substrate 11 is located is defined as upward. Note that the direction in this disclosure does not mean the direction in which the product is actually used. For convenience, each direction is expressed using the Cartesian coordinate system XYZ, where upward is the positive side of the Z direction. In this disclosure, "plan view" means viewing the composite wiring board 1 from above (the positive side in the Z direction), and "front view" means viewing the composite wiring board 1 from the side (the positive side in the X direction), and includes planar perspective or frontal perspective.

[0010] In the following descriptions, expressions such as "constant," "orthogonal," "perpendicular," "parallel," or "equal" may be used. These expressions do not necessarily strictly mean "constant," "orthogonal," "perpendicular," "parallel," or "equal." That is, these expressions allow for deviations, for example, in manufacturing accuracy or installation accuracy. Numerical ranges expressed using "~" include the numbers before and after them as the lower and upper limits, respectively.

[0011] Optical waveguide substrates are used as light sources in devices such as head-mounted displays and AR (Augmented Reality) glasses. Portable devices such as head-mounted displays and AR glasses can be exposed to harsh environments, including drops and vibrations. Therefore, when using optical waveguide substrates connected to external substrates, it is necessary to reduce the possibility of damage or deformation to the optical waveguide substrate.

[0012] The composite wiring board, electronic module, and electronic device of this disclosure can reduce damage and deformation of the optical waveguide board.

[0013] 1. [Composite Wiring Board] A composite wiring board 1 according to one embodiment of the present disclosure mainly comprises an optical waveguide substrate 10, an external substrate 20, a conductive member 30, and an insulator 40, as shown in Figures 1 to 3, etc.

[0014] The optical waveguide substrate 10 comprises a base body 11, an optical waveguide 12, and an electrode 14. The base body 11 has a first base body surface 11a on its upper surface (corresponding to the upper side of the paper in Figure 3), and a second base body surface 11b on the surface opposite to the first base body surface 11a. The shape of the base body 11 is not particularly limited and may be a plate-like member exhibiting a rectangular shape in plan view, or it may have any other shape.

[0015] The material of the substrate 11 is not particularly limited and may be, for example, conductive silicon, or insulating ceramic or resin. Examples of ceramics include aluminum oxide sintered bodies, mullite sintered bodies, silicon carbide sintered bodies, aluminum nitride sintered bodies, silicon nitride sintered bodies, and glass ceramic sintered bodies. Examples of resins include epoxy resin, polyimide resin, polyester resin, acrylic resin, phenolic resin, and fluororesin.

[0016] The optical waveguide 12 has an opening 13 located on the first substrate surface 11a and opening to the first upper surface 12a. Furthermore, the optical waveguide 12 has a cladding 121 and a core 122 located inside the cladding 121 and capable of transmitting light. Furthermore, the core 122 has an incident end 123a exposed from the cladding 121 to the opening 13 and an exit end 123b that penetrates the inside of the cladding 121 and reaches the outside of the optical waveguide 12.

[0017] The refractive index of the core 122 is greater than that of the cladding 121. The difference in refractive index between the core 122 and the cladding 121 depends on the structure of each core 122, such as its shape, but can be set to, for example, 0.01 to 2.0. This provides an optical waveguide 12 in which light propagates along the core 122.

[0018] The cross-sectional shape of the core 122 perpendicular to the extension direction may be rectangular, trapezoidal, or any other shape. The width and height of the core 122 are, for example, about 2 to 10 μm, and may be constant or not constant from the incident end 123a to the exit end 123b. The core 122 may be straight from the incident end 123a to the exit end 123b, or it may have a curved section.

[0019] The core 122 may be one or multiple. The number of cores 122 is, for example, the same as the number of electronic elements 101 (light-emitting elements) electrically connected to the electrode 14. Multiple cores 122 may be spaced apart from each other, connected to each other at the emission end 123b, or merged along the way. If multiple cores 122 are spaced apart from each other, the emission ends 123b of the multiple cores 122 may be spaced apart from each other and facing the same direction in a nearby location.

[0020] The cladding 121 may have protrusions that extend along the core 122 and project upward from the core 122. The height of the protrusions may be, for example, 2 to 10 μm, which is about the same as the height of the core 122, or it may be lower than the height of the core 122.

[0021] The materials of the cladding 121 and core 122 that constitute the optical waveguide 12 are not particularly limited as long as they are light-transmitting materials. The materials of the cladding 121 and core 122 can be, for example, glass, resin, etc. More specifically, the material of the cladding 121 is silicon dioxide (SiO₂ ２ ) and the material of core 122 may be the same as silicon oxynitride (SiON), also known as silicon oxynitride.

[0022] The shape of the opening 13 that opens in the first upper surface 12a of the optical waveguide 12 is not particularly limited, but may be substantially rectangular in shape as shown in Figures 1 and 2, or it may be any other shape. Furthermore, the opening 13 may penetrate the optical waveguide 12 from the first upper surface 12a, or it may be a recessed shape such as a concave cross-section without penetrating it.

[0023] The electrode 14 extends from the inside of the opening 13 of the optical waveguide 12 to the outside of the opening 13. The material and number of electrodes 14 arranged on the optical waveguide substrate 10 are not particularly limited. The material of the electrode 14 can be any conductive material, and examples include the use of Ti, Pt, Au, Al, Cu, or alloys thereof. Furthermore, multiple electrodes 14 may be arranged at predetermined intervals.

[0024] The external substrate 20 has wiring conductors 21 arranged on a first external substrate surface 20a corresponding to the upper surface of the external substrate 20. The external substrate 20 may be, for example, a printed circuit board (PCB). The printed circuit board may be flexible, and may be a so-called flexible printed circuit board (FPC). If the external substrate 20 is an FPC, the handling of the external substrate 20 becomes easier, and the degree of design freedom is improved. The external substrate 20 may be in contact with the optical waveguide substrate 10, or it may be separated from it. The material of the wiring conductors 21 may be the same as that of the electrodes 14 described above, or it may be different. In the composite wiring substrate 1 of this disclosure, the external substrate 20 has a second external substrate surface 20b facing the first external substrate surface 20a. Furthermore, multiple wiring conductors 21 may be arranged on the first external substrate surface 20a at predetermined intervals.

[0025] The conductive member 30 electrically connects the electrodes 14 of the optical waveguide substrate 10 and the wiring conductors 21 of the external substrate 20. For example, bonding wires or lead terminals can be used as the conductive member 30. Such bonding wires or the like are connected to the electrodes 14 and the wiring conductors 21, respectively, enabling electrical conductivity between the electrodes 14 and the wiring conductors 21. The electrical connection between the electrodes 14 and the wiring conductors 21 and the conductive member 30 such as the bonding wire may be made by soldering or tin bonding, for example.

[0026] The insulator 40 covers the conductive member 30 from the first substrate surface 11a side of the optical waveguide substrate 10 and from the first external substrate surface 20a side of the external substrate 20. In other words, the insulator 40 covers the entire conductive member 30 from above (corresponding to the top of the paper in Figure 3) the optical waveguide substrate 10 and the external substrate 20. This reduces the possibility of the conductive member 30 being directly exposed to the outside.

[0027] As shown in Figure 3, the insulator 40 covers a portion of the optical waveguide substrate 10 and the external substrate 20, and may have a shape that gradually rises towards the center, with a top portion 41 at its highest point. For the sake of simplicity, Figures 1 to 3 show a view through the inside of the insulator 40, illustrating the configuration of the conductive member 30 and other components covered by the insulator 40.

[0028] The insulator 40 only needs to be insulating (in other words, non-conductive), and its transparency is not limited. Therefore, the insulator 40 may, for example, be made of a transparent insulating material, and as shown in Figure 1, the structure of the conductive member 30, etc., may be visible from the outside even when covered with the insulator 40. On the other hand, the insulator 40 may be made of an insulating material such as black, and the inside of the insulator 40 may not be visible.

[0029] The shape of the insulator 40 when viewed from the front is not particularly limited, but for example, as shown in Figure 3, it may be a mountain-shaped shape with the highest point near the center, or it may be hemispherical or rectangular. Furthermore, the top portion 41 is not limited to one location, and for example, it may have two or more top portions (two or more points), or it may have a semi-circular shape when viewed from the side, with the top portions 41 continuously existing along the direction of the second insulator width W2 described later, or it may have a rectangular shape when viewed from the side, with the entire rectangular upper surface constituting the top portion 41.

[0030] In other words, in the composite wiring board 1 of this disclosure, the insulator 40 only needs to have a predetermined height from the first substrate surface 11a of the substrate 11 when viewed from the front or back (viewed from the positive or negative side in the X direction), or from the side (viewed from the positive or negative side in the Y direction).

[0031] In the composite wiring board 1 of this disclosure, the insulator 40 has a mountain-like shape, as shown in Figure 3, with the peak being higher near the center than near the edges, and has a top portion 41 at the highest point from the first base surface 11a. At this time, the height from the first base surface 11a to the top portion 41 of the insulator 40 (insulator height H1) is higher than the height from the first base surface 11a to the first upper surface 12a, which corresponds to the upper surface of the optical waveguide 12 (optical waveguide height H2).

[0032] Because the conductive member 30 is covered with an insulator 40, the possibility of the entire conductive member 30 connecting the electrode 14 and the wiring conductor 21 being exposed to the outside is reduced, and the conductive member 30 is protected. As a result, the possibility of the conductive member 30 connecting the electrode 14 and the wiring conductor 21 falling off the electrode 14 or the wiring conductor 21, or of the conductive member being damaged is reduced.

[0033] Furthermore, by installing the insulator 40 so as to satisfy the condition "insulator height H1 > optical waveguide height H2", even if an impact is applied to the composite wiring board 1 from an external component, the insulator 40, which has a top portion 41 that protrudes to a position higher than the optical waveguide 12, increases the likelihood that the optical waveguide 12 will first come into contact with a part of the insulator 40.

[0034] As a result, the possibility of components directly contacting the optical waveguide 12 and causing impacts is reduced. This makes it easier to avoid damage or deformation to the optical waveguide 12 itself.

[0035] The insulator 40 may contain a resin material. Examples of resin materials include thermosetting epoxy resins, phenolic resins, or urethane resins. Alternatively, the insulator 40 may be a photocurable resin (e.g., UV-curable resin) that can be cured by ultraviolet light.

[0036] These resin materials utilize liquid raw materials that have been pre-adjusted to a predetermined viscosity. The liquid material is supplied to cover the conductive member 30 connected between the electrode 14 and the wiring conductor 21, and by applying a heat curing treatment or ultraviolet curing treatment, the material can be easily constructed by adjusting the curing time to create a shape with a raised center. The shape of the insulator 40, in particular the height of the top portion 41 (insulator height H1), can be arbitrarily changed or adjusted within a predetermined range by adjusting the viscosity of the liquid material. Furthermore, the height of the top portion 41 of the insulators 40 and 45 can also be arbitrarily changed or adjusted by the heating rate of the liquid material, the temperature maintained after heating, the temperature maintained after heating, etc.

[0037] The insulator 40 has the function of preventing the conductive member 30 from being exposed to the outside. For this reason, the composite wiring board 1 may have, for example, a space enclosed between the first base surface 11a and the first outer substrate surface 20a and the hollow insulator 40, and the conductive member 30 may connect the electrodes 14 and the wiring conductors 21 within this space. That is, the insulator 40 may be in a shape that is completely filled inside, or it may be in a shape that has a space inside. In other words, the insulator 40 may be dome-shaped. Furthermore, the insulator 40 itself may be made of a porous material, and may be made of a material that contains a plurality of fine voids inside the insulator 40.

[0038] The insulator 40 contains a resin material, which reduces the possibility of short circuits occurring between the conductive member 30, the electrode 14, and the wiring conductor 21. Furthermore, because the insulator 40 contains a resin material, the heat generated by the energization of the conductive member 30 may be dissipated to the outside through the insulator 40. This reduces the possibility of the conductive member 30 itself breaking due to the heat generated by the conductive member 30, such as a bonding wire composed of a fine diameter.

[0039] The optical waveguide substrate 10 may further have a cover 15 that covers the opening 13 from the first upper surface 12a side of the optical waveguide 12. Furthermore, the insulator 40 may be spaced apart from the cover 15 that covers the opening 13. In other words, the insulator 40 and the cover 15 do not have to be in direct contact.

[0040] This reduces the possibility that the stress from the insulator 40 is transmitted to the lid 15. More specifically, when the insulator 40 is a liquid material before curing, a stress that causes the insulator 40 to slightly contract in the central direction of the insulator 40 occurs when the insulator 40 cures, but the possibility that this stress is transmitted to the lid 15 can be reduced. As a result, the possibility that the position of the lid 15 covering the opening 13 is displaced or detached is reduced, and it becomes possible to maintain the airtightness of the internal space of the opening 13 covered by the lid 15 and in which the electrode 14 and the like are arranged.

[0041] The material constituting the lid 15 is not particularly limited, and may be silicon, ceramic, resin, or the like. Also, the material of the lid 15 may be the same as or different from the material of the base 11.

[0042] In the composite wiring board 1, the insulator height H1 may be higher than the lid height H3 from the first base surface 11a to the top surface 15a of the lid 15.

[0043] By satisfying the condition of "insulator height H1 > lid height H3", even if an impact is applied to the composite wiring board 1 by a component or the like from the outside, the insulator 40 having the top 41 protruding to a position higher than the lid 15 makes it highly likely that a part of the insulator 40 is contacted by the component or the like before the lid 15. As a result, the possibility that the component or the like contacts the lid 15 and applies an impact is reduced. Thereby, the possibility that the position of the lid 15 is displaced, the lid 15 is detached from the opening 13, or the lid 15 is damaged is reduced. Therefore, the possibility that the airtightness of the space in which the electronic element 101 is housed is reduced due to the displacement of the lid 15 or the like is reduced.

[0044] Further, the optical waveguide 12 may further have a step portion 16 outside the opening 13. In the composite wiring board 1 of the present disclosure, the step portion 16 is located outside the opening 13 (the left side of the paper surface in FIGS. 2 and 3). Also, the optical waveguide 12 has a second upper surface 12b that further extends to a position further outside (left side) from the step portion 16. The electrode 14 extending outward from the opening 13 is arranged on the second upper surface 12b.

[0045] In a plan view, the insulator 40 may be spaced apart from the stepped portion 16 of the optical waveguide 12. That is, the insulator 40 and the stepped portion 16 do not have to be in direct contact. This reduces the possibility that stress from the insulator 40 will be transmitted to the stepped portion 16. More specifically, if the insulator 40 is a liquid material before curing, a slight contraction stress is generated toward the center of the insulator 40 when it hardens, but the possibility that this stress will be transmitted to the stepped portion 16 can be reduced. As a result, the possibility that stress from the insulator 40 will be transmitted to the cladding 121 of the optical waveguide 12 via the stepped portion 16 is reduced, and the possibility that the optical waveguide 12 will be distorted or damaged can be reduced. As shown in Figure 3 and other figures, the composite wiring board 1 of this disclosure may have a gap formed between the end of the second upper surface 12b of the optical waveguide 12 and the end of the external substrate 20. The position of the insulator 40 in the gap increases the contact area with the optical waveguide substrate 10 and the external substrate 20, reducing the possibility of the insulator 40 falling off or deforming even if components or other objects come into contact with it from the outside. In addition, a part of the base body 11 may protrude from the end of the second upper surface 12b, and the end of the base body 11 may be in contact with the end of the external substrate 20. Since a part of the insulator 40 fills this gap, direct contact between the insulator 40 and the stepped portion 16 is further avoided.

[0046] In a plan view, the insulator 40 has a first insulator width W1 along the first direction (corresponding to the left-right direction in Figure 2) in which the optical waveguide substrate 10 and the external substrate 20 are arranged side by side, and a second insulator width W2 along the second direction (corresponding to the up-down direction in Figure 2) perpendicular to the first direction. In this case, the second insulator width W2 may be larger than the first insulator width W1. That is, the insulator 40 may satisfy the condition "second insulator width W2 > first insulator width W1". In other words, the insulator 40 may extend along a direction perpendicular to the direction in which the core 122 in the optical waveguide 12 extends. This makes it possible to efficiently cover multiple electrodes 14 and multiple wiring conductors 21 in a composite wiring substrate 1. The shape of the insulator 40 in a plan view is not particularly limited and may be rectangular, elliptical, or the like.

[0047] The insulator 40 may be located on the side opposite to the emission end 123b of the core 122 that penetrates the inside of the cladding 121 constituting the optical waveguide 12. Thereby, the emission end 123b is not blocked by the insulator 40.

[0048] The composite wiring board 1 of the present disclosure may further include a support substrate 50 that faces the first substrate surface 11a corresponding to the upper surface side of the substrate 11 and is located on the second substrate surface 11b side corresponding to the lower surface side of the substrate 11. Further, the thermal conductivity of the support substrate 50 may be higher than the thermal conductivity of the substrate 11. Thereby, the heat generated by the conductive member 30 is more likely to be transmitted to the support substrate 50 side through the substrate 11 of the optical waveguide substrate 10. As a result, the possibility that the conductive member 30 becomes high temperature is reduced, and the possibility that the conductive member 30 is disconnected and the possibility that the optical waveguide substrate 10 is deformed are reduced. On the other hand, when the thermal conductivity of the support substrate 50 is lower than the thermal conductivity of the substrate 11, heat may be dissipated by using a support substrate having a larger surface area than the substrate 11.

[0049] The support substrate 50 may support the substrate 11 and extend to the external substrate 20 to support the external substrate 20 together. Thereby, it becomes possible to stabilize the relative positions of the optical waveguide substrate 10 and the external substrate 20. A part of the heat generated by the conductive member 30 can be transmitted to the support substrate 50 side through the external substrate 20. Thereby, the possibility that the conductive member 30 is disconnected and the possibility that the optical waveguide substrate 10 is deformed are further reduced.

[0050] As the support substrate 50, for example, a metal material such as aluminum or copper can be used. In addition, as the support substrate 50, a carbon material such as graphite, a ceramic material such as aluminum nitride, or a resin material such as glass epoxy may be used.

[0051] The composite wiring board 1 of this disclosure may further include a first heat transfer layer 60 between the second substrate surface 11b of the substrate 11 and the first support substrate surface 50a corresponding to the upper surface of the support substrate 50. This makes it possible to transfer heat generated by the conductive member 30 and electronic element 101 to the support substrate 50 more quickly via the substrate 11. The first heat transfer layer 60 can be formed by, for example, using a sintering paste containing silver particles and performing a sintering process. When a sintering paste containing silver particles is used for the first heat transfer layer 60, it does not need to contain resin components after sintering. The first heat transfer layer 60 is not limited to the above, and other materials that provide good heat transfer between the substrate 11 and the support substrate 50 may be used. The first heat transfer layer 60 may also be provided between the external substrate 20 and the support substrate 50. As the first heating layer 60, for example, silicone grease or epoxy resin containing silver particles can be used.

[0052] As shown in Figures 1 to 3, the composite wiring board 1 of this disclosure may further have through holes 70 that penetrate at least one of the external substrate 20 or the optical waveguide substrate 10 and the support substrate 50. Furthermore, the composite wiring board 1 may further include a heat dissipation member 80 fixed to the second support substrate surface 50b corresponding to the lower surface side of the support substrate 50 via the through holes 70. By including the heat dissipation member 80, the contact area with the support substrate 50 is increased. As a result, it becomes possible to efficiently dissipate the heat transferred from the base body 11 to the support substrate 50. For example, a metal material such as aluminum or copper can be used as the heat dissipation member 80.

[0053] Furthermore, the position and number of through holes 70 are not particularly limited. For example, as shown in Figure 2, the through holes 70 may be arranged in two locations along the second direction so as to penetrate the external substrate 20 and the support substrate 50 that extends to the lower side of the external substrate 20 (the second external substrate surface 20b side).

[0054] Furthermore, if the through-hole 70 is located on the external substrate 20 side, for example, a gap of at least 0.025 mm may be left between the through-hole 70 and the wiring conductor 21 of the external substrate 20. Also, the support substrate 50 and the heat dissipation member 80 can be fixed through the through-hole 70 using screws, for example. In this case, the shortest distance between the through-hole 70 and the wiring conductor 21 may be the same as or greater than the amount the screw protrudes from the external substrate 20.

[0055] The composite wiring board 1 of this disclosure may further include a second heat transfer layer 90 between the second support substrate surface 50b of the support substrate 50 and the first heat dissipation member surface 80a, which corresponds to the upper surface of the heat dissipation member 80. By having the second heat transfer layer 90, the composite wiring board 1 of this disclosure reduces the gap between the second support substrate surface 50b and the first heat dissipation member surface 80a, and increases the contact area between both surfaces. As a result, it becomes possible to improve heat transfer efficiency, and heat generated from the conductive member 30 can be efficiently transferred to the heat dissipation member 80 through the base 11 of the optical waveguide substrate 10 and the support substrate 50.

[0056] Furthermore, the composite wiring board 1 of this disclosure may have a plurality of conductive members 30, and the spacing between adjacent conductive members 30 may be arranged to expand radially from the optical waveguide board 10 side to the external board 20 side. That is, the spacing between adjacent conductive members 30 along the second direction may gradually expand from the optical waveguide board 10 side (electrode 14 side) to the external board 20 side (wiring conductor 21 side). This does not restrict the arrangement of the plurality of wiring conductors 21 on the external board 20 connected to the optical waveguide board 10. Furthermore, when a conductive bonding material such as solder is used to connect the conductive members 30 to the electrodes 14 and the wiring conductors 21, the spacing between adjacent wiring conductors 21 can be increased. Therefore, compared to the case where the spacing between adjacent wiring conductors 21 is narrow, the possibility of solder overflowing from the wiring conductors 21 and coming into contact with adjacent wiring conductors 21, causing a short circuit, can be reduced.

[0057] In the composite wiring board 1 of this disclosure, as described above, the spacing of the conductive members 30 is not limited to being arranged in a radial pattern from the optical waveguide board 10 side toward the external board 20 side. That is, the spacing between a plurality of adjacent electrodes 14 on the optical waveguide board 10 may be the same as the spacing between a plurality of adjacent wiring conductors 21 on the external board 20 that are opposite to the electrodes 14. In such a case, the conductive members 30, such as a plurality of bonding wires, may be arranged parallel to each other to connect the electrodes 14 and the wiring conductors 21.

[0058] The shape of the electrodes 14 constituting the optical waveguide substrate 10 is not particularly limited. For example, the electrode 14 may have a shape that combines a straight section, which is straight in plan view, and a circular section, which is connected to the straight section and is circular in plan view. In this case, the width of the straight section may be larger than the diameter of the circular section. Furthermore, the circular section may be located in the middle of the straight section. A conductive bonding material such as solder can be applied to the circular section when it is joined to the conductive member 30. Compared to a rectangular shape, this reduces the possibility of the electrode 14 peeling off from the substrate 11 or the substrate 11 itself warping due to stress generated when the conductive bonding material hardens or warping of the substrate 11.

[0059] The electrode 14 may have multiple layers. The multiple layers may consist of two layers, for example, an upper electrode (or upper conductor) and a lower electrode (or lower conductor). For example, if the electrode 14 has the circular portion described above, the circular portion itself may be composed of multiple layers. In this case, both the upper electrode and the lower electrode can be circular in shape when viewed from above. In addition, the portion of the electrode 14 having multiple layers will be partially thicker. The partially thickened electrode 14 facilitates connection between the electrode 14 and the conductive member 30. Furthermore, having multiple layers in the electrode 14 allows for different materials to be used for each layer. For example, a metal suitable for forming wiring may be applied to the lower electrode, and a metal such as Au with high wettability for conductive bonding material may be applied to the upper electrode. In plan view, the outer edge of the upper electrode may be spaced apart from the outer edge of the lower electrode. More specifically, in plan view, the outer edge of the upper electrode may be located inward from the outer edge of the lower electrode.

[0060] Each of the multiple electrodes 14 may have a straight portion and a circular portion. In this case, in a plan view, the multiple circular portions may be arranged alternately in a staggered pattern. This makes it possible to reduce the distance between the electrodes 14 compared to the case where the multiple circular portions are arranged in a straight line in the X direction. Furthermore, this configuration makes it possible to increase the size of the multiple circular portions.

[0061] When multiple circular portions are arranged alternately in a staggered pattern, the centers of the circular portions of adjacent electrodes 14 may be offset in the direction in which the straight portion extends (Y direction). Also, the circular portions of adjacent electrodes 14 may partially overlap in the direction in which the straight portion extends.

[0062] 2. [Electronic Module] As shown in Figure 1, the electronic module 100 may include a composite wiring board 1, an electronic element 101, a module cover, and a lens.

[0063] The electronic element 101 may be electrically connected to the electrode 14 on the composite wiring board 1. The electronic element 101 and the electrode 14 can be electrically connected by, for example, a brazing material, a conductive adhesive, a bonding wire, etc. The electronic element 101 can also be located inside the opening 13 of the cladding 121 that constitutes the optical waveguide 12. Furthermore, the number of electronic elements 101 is not particularly limited and may be one or more.

[0064] The electronic element 101 may be, for example, a light-emitting element, and more specifically, a laser diode (LD). The light-emitting element emits light at a predetermined wavelength and can cause light to be incident on the incident end 123a of the core 122. Alternatively, the electronic element 101 may be a light-receiving element. In this case, the electronic module 100 may receive light input from outside the electronic module 100 through the core 122 using the light-receiving element. In this case, the electronic element 101 may be, for example, a photodiode. Furthermore, the light may include electromagnetic waves outside the visible light spectrum, such as infrared rays, as long as the wavelength can be transmitted by the optical waveguide 12. Accordingly, the electronic element 101 may be a temperature-measuring element, for example. A temperature-measuring element is, for example, a thermistor.

[0065] The module cover may be the cover 15 of the composite wiring board 1 described above. The cover 15 may be located above the electronic element 101 which is placed inside the opening 13. As shown in Figure 1, if the cladding 121 has an opening 13, the cladding 121 may be placed on the upper surface of the cladding 121 (the first upper surface 12a of the optical waveguide 12) so as to cover the upper side of the electronic element 101, in order to seal the inside of the opening 13 in an airtight state.

[0066] The lid 15 may be flat or cup-shaped with a recess on its bottom surface (the lower surface in the Z direction).

[0067] As already mentioned, the material of the lid 15 may be, for example, glass, silicon, or metal. Examples of glass include quartz, borosilicate, and sapphire. Examples of metals include aluminum, copper, iron, and alloys such as Fe-Ni-Co. If the material of the lid 15 is metal, the lid 15 may have a plating layer on its surface. Examples of plating layer materials include gold and nickel.

[0068] The electronic module 100 may be provided with an annular conductor (seal ring) between the cover 15 and the optical waveguide substrate 10. By joining the cover 15 and the composite wiring board 1 with the conductor in between, the airtightness is improved compared to when they are directly joined with a resin-based adhesive.

[0069] The lens may be positioned in the direction from which light is emitted from the optical waveguide 12. The lens may be, for example, a convex lens, a diffracting lens, a rod lens, a ball lens, etc. The lens may also be a component that has the function of converting the light emitted from the optical waveguide 12 into parallel light.

[0070] 3. [Electronic Devices] The electronic device 200 may include an electronic module 100 and a display unit 201. The electronic device 200 may be, for example, AR glasses, a head-up display, a projector, etc.

[0071] For example, if the electronic device 200 is AR glasses, as shown in Figure 4, the electronic device 200 may further include temples 202 and a control unit 203. In this case, the electronic module 100 may be located inside the temples 202. The temples 202 may be bendable or not. If they are bendable, the electronic module 100 does not need to emit light when bent.

[0072] The display unit 201 may display information using light emitted from the electronic module 100. The display unit 201 may include a scanning mirror 204 and a light guide unit 205. The scanning mirror 204 is, for example, a MEMS (Micro-Electro Mechanical Systems) mirror and scans the light emitted from the electronic module 100. The scanned light is input to a light guide plate, half mirror, etc., of the light guide unit 205. The scanning mirror 204 may be located inside the arbor 202.

[0073] The light guide unit 205 may have a light guide plate or a half mirror as described above, and may be capable of projecting incident light onto the user's eyeball. The light guide unit 205 may also be light-transmitting. For example, the light guide unit 205, waveguide system, half mirror system, etc., may allow the user to view the projected image superimposed on the actual image transmitted through the display unit 201. If the light guide unit 205 is a half mirror system, the light guide unit 205 may be separated from the glass surface. The light guide unit 205 may be transparent or colored to block a portion of the transmitted light.

[0074] The projected image data is not particularly limited, but may be received from an external source via wireless communication or the like, or it may be generated by the control unit 203 based on measurement results from sensors equipped in the AR glasses. Furthermore, these image data may be used in combination.

[0075] The control unit 203 includes, for example, a CPU, RAM, non-volatile memory, etc., and performs control processing related to image display. In addition to the above, the control unit 203 may also include an LD driver for controlling the LD, a MEMS driver for scanning and controlling the MEMS mirror, etc. The control unit 203 may be located inside or on the side of the handle 202, or it may be located outside via a cable. The control unit 203 may also be located on the aforementioned external substrate 20.

[0076] The glass surface including the light guide 205 may be separate on the left and right sides, as shown in Figure 4, or it may be a single unit. The glass surface may have a large curved surface, especially in the case of a half-mirror system.

[0077] The AR glasses electronic device 200 may also be a head-mounted display having a band, support, etc. for being attached to a person's head instead of the temples 202.

[0078] The electronic device 200 may also have a communication unit, a battery, etc. If the electronic device 200 is AR glasses, the communication unit, battery, etc. may be located inside or on the side of the temple 202, or they may be located outside via a cable.

[0079] The following are further examples of embodiments of the composite wiring board, electronic module, and electronic device relating to this disclosure.

[0080] (1) One embodiment of a composite wiring board according to the present disclosure comprises an optical waveguide substrate, an external substrate, a conductive member, and an insulator. The optical waveguide substrate has a base body, an optical waveguide, and electrodes. The base body includes a first base body surface. The optical waveguide is located on the first base body surface and includes an opening in the first strip surface. The electrodes extend from the inside of the opening to the outside of the opening. The external substrate has wiring conductors on the first external substrate surface. The conductive member electrically connects the electrodes and the wiring conductors. The insulator covers the conductive member from the first base body surface side and the first external substrate surface side. The height from the first base body surface to the top of the insulator is greater than the height from the first base body surface to the first top surface.

[0081] (2) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (1) above, wherein the insulator contains a resin material.

[0082] (3) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (1, J or (2) above, further comprising a cover that covers the opening from the first upper surface side, wherein in a plan view, the insulator is spaced apart from the cover.

[0083] (4) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (1) to (3) above, wherein the optical waveguide further has a stepped portion located outside the opening, and in a plan view, the insulator is spaced apart from the stepped portion.

[0084] (5) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (1) to (3) above, wherein in a plan view, the insulator has a first insulator width along a first direction in which the optical waveguide substrate and the external substrate are arranged side by side, and a second insulator width along a second direction perpendicular to the first direction, wherein the second insulator width is greater than the first insulator width.

[0085] (6) One embodiment of a composite wiring board according to the present disclosure is a composite wiring board as described in (1) to (5) above, wherein the optical waveguide comprises a cladding and a core located within the cladding and capable of transmitting light, the core having an incident end exposed to the opening and an exit end penetrating through the cladding from the incident end and reaching outside the cladding, and the insulator is located on the opposite side from the exit end.

[0086] (7) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (1) to (6) above, wherein the substrate further includes a second substrate surface facing the first substrate surface, and further comprises a support substrate located on the side of the second substrate surface.

[0087] (8) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (7) above, wherein the thermal conductivity of the support substrate is higher than the thermal conductivity of the base material.

[0088] (9) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (7) above, further comprising a first heat transfer layer containing metal between the second substrate surface and the first support substrate surface of the support substrate.

[0089] (10) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (7) above, further comprising a through hole that penetrates at least one of the external substrate or the optical waveguide substrate and the support substrate, and further comprising a heat dissipation member fixed to the second support substrate surface side of the support substrate facing the first support substrate via the through hole.

[0090] (11) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (10) above, further comprising a second heat transfer layer between the second support substrate surface of the support substrate and the first heat dissipation member surface of the heat dissipation member.

[0091] (12) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (1) to (11) above, wherein it has a plurality of conductive members, and the spacing between adjacent conductive members expands radially from the optical waveguide substrate side toward the external substrate.

[0092] (13) One embodiment of the composite wiring board according to the present disclosure is the composite wiring board described in (3) to (12) above, wherein the height is greater than the height from the first substrate surface to the top surface of the cover.

[0093] (14) One embodiment of the electronic module relating to the present disclosure comprises a composite wiring board as described in any of (1) to (13) above, an electronic element electrically connected to the electrode, and a module cover covering the electronic element.

[0094] (15) One embodiment of the electronic device relating to the present disclosure comprises the electronic module described in (14) above and a display unit, wherein the electronic element is a light-emitting element, and the display unit displays information using light emitted from the electronic module.

[0095] Furthermore, details shown in the embodiments described above may be modified as appropriate without departing from the spirit of this disclosure. The scope of this disclosure includes the scope of the invention as described in the claims and its equivalents. Various combinations of each embodiment are not limited to the examples of embodiments described above. Combinations of each embodiment are also possible.

[0096] 1 Composite wiring board 10 Optical waveguide board 11 Base body 11a First base body surface 11b Second base body surface 12 Optical waveguide 12a First upper surface 12b Second upper surface 13 Opening 14 Electrode 15 Cover 15a Top surface 16 Step portion 20 External substrate 20a First external substrate surface 20b Second external substrate 21 Wiring conductor 30 Conductive member 40 Insulator 41 Top portion 50 Support substrate 50a First support substrate surface 50b Second support substrate surface 60 First heat transfer layer 70 Through hole 80 Heat dissipation member 80a First heat dissipation member surface 90 Second heat transfer layer 100 Electronic module 101 Electronic element 121 Cladding 122 Core 123a Incident end 123b Output end 200 Electronic device 201 Display unit 202 Handle 203 Control unit 204 Scanning mirror 205 Light guide unit H1 Insulator height H2 Optical waveguide height H3 Cover height W1 First insulator width W2 Second insulator width

Claims

1. A composite wiring board comprising: a substrate including a first substrate surface; an optical waveguide substrate having an optical waveguide located on the first substrate surface and having an opening on a first upper surface; an electrode extending from the inside of the opening to the outside of the opening; an outer substrate having a wiring conductor on a first outer substrate surface; a conductive member electrically connecting the electrode and the wiring conductor; and an insulator covering the conductive member from the first substrate surface side and the first outer substrate surface side, wherein the height from the first substrate surface to the top of the insulator is greater than the height from the first substrate surface to the first upper surface.

2. The composite wiring board according to claim 1, wherein the insulator contains a resin material.

3. The composite wiring board according to claim 1 or 2, wherein the optical waveguide substrate further has a cover that covers the opening from the first upper side, and in a plan view, the insulator is spaced apart from the cover.

4. The composite wiring board according to any one of claims 1 to 3, wherein the optical waveguide further has a stepped portion located outside the opening, and in a plan view, the insulator is spaced apart from the stepped portion.

5. In a plan view, the insulator has a first insulator width along a first direction in which the optical waveguide substrate and the external substrate are arranged side by side, and a second insulator width along a second direction perpendicular to the first direction, wherein the second insulator width is greater than the first insulator width, as described in any one of claims 1 to 3.

6. The composite wiring board according to any one of claims 1 to 5, wherein the optical waveguide comprises a cladding and a core located within the cladding and capable of transmitting light, the core having an incident end exposed to the opening and an exit end penetrating the cladding from the incident end and reaching outside the cladding, and the insulator is located on the opposite side of the exit end.

7. The composite wiring board according to any one of claims 1 to 6, wherein the substrate further includes a second substrate surface facing the first substrate surface, and further comprises a support substrate located on the side of the second substrate surface.

8. The composite wiring board according to claim 7, wherein the thermal conductivity of the support substrate is higher than the thermal conductivity of the substrate.

9. The composite wiring board according to claim 7, further comprising a first heat transfer layer containing metal between the second substrate surface and the first support substrate surface of the support substrate.

10. The composite wiring board according to claim 7, further comprising a through hole that penetrates at least one of the external substrate or the optical waveguide substrate and the support substrate, and further comprising a heat dissipation member fixed to the second support substrate surface side of the support substrate facing the first support substrate via the through hole.

11. The composite wiring board according to claim 10, further comprising a second heat transfer layer between the second support substrate surface of the support substrate and the first heat dissipation member surface of the heat dissipation member.

12. A composite wiring board according to any one of claims 1 to 11, having a plurality of conductive members, wherein the spacing between adjacent conductive members expands radially from the optical waveguide substrate side toward the external substrate.

13. The composite wiring board according to any one of claims 3 to 12, wherein the height from the first base surface to the top is greater than the height from the first base surface to the top surface of the cover.

14. An electronic module comprising: a composite wiring board according to any one of claims 1 to 13; an electronic element electrically connected to the electrode; and a module cover covering the electronic element.

15. An electronic device comprising an electronic module as described in claim 14 and a display unit, wherein the electronic element is a light-emitting element and the display unit displays information using light emitted from the electronic module.

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