Optical connection assembly and mounting method

Abstract

An optical connection assembly of this disclosure includes: a first optical-connection component (110); and a second optical-connection component (120) including at least one optical waveguide (500). Either one of the first optical-connection component and the second optical-connection component has a projection (150), and the other of the first optical-connection component and the second optical-connection component has a hole (120d). The first optical-connection component and the second optical-connection component form a positioning structure that maintains relative positions to each other by insertion of the projection into the hole. The first optical-connection component includes: a first reference surface (110a) on which the projection or the hole is provided; and an opening (110c) formed in the first reference surface and exposing a light input / output part on a principal surface from the first reference surface. The second optical-connection component includes: a second reference surface (120b) on which the projection or the hole is provided and facing the first reference surface; and a connection end-surface (120a) protruding from the second reference surface and disposed inside the opening, facing the principal surface exposed from the opening, and having a tip end of the optical waveguide exposed and facing the light input / output part on the principal surface. A distance between the connection end-surface and the principal surface (30a) exposed from the opening is 50 μm or less.

Description

Optical connection assembly and mounting method

[0001] This application claims priority to Japanese Patent Application No. 2023-144202, filed on September 6, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] An optical communication module that performs optical communication via an optical transmission medium such as an optical fiber has a structure in which a communication LSI (Large Scale Integration) and multiple optical IC (Integrated Circuit) substrates electrically connected to the communication LSI are mounted on the same substrate. An optical connection assembly for optically connecting the optical IC and the optical transmission medium is attached to the optical IC substrate. For example, Patent Document 1 discloses an optical connection assembly in which a receptacle disposed on the optical IC substrate and a ferrule that holds the tip of an optical fiber are fitted together using a guide pin. In this optical connection assembly, the ferrule and the receptacle are arranged to face each other with a gap between them. The optical fiber and the optical IC are optically connected via lenses provided on the ferrule and the receptacle, respectively.

[0003] US Patent Application Publication No. 2016 / 0370544

[0004] The optical connection assembly of the present disclosure includes a first optical connection part mounted on a main surface of a circuit board including at least one optical input / output part, and a second optical connection part including at least one optical waveguide and connected to the first optical connection part, wherein one of the first optical connection part and the second optical connection part has a protrusion, and the other of the first optical connection part and the second optical connection part has a hole, and the first optical connection part and the second optical connection part form a positioning structure that maintains their relative positions by inserting the protrusion into the hole. the first optical connecting part includes a first reference surface on which a protrusion or a hole is provided, and an opening formed on the first reference surface to expose an optical input / output part on the main surface from the first reference surface; the second optical connecting part includes a second reference surface on which a protrusion or a hole is provided and facing the first reference surface, and a connection end surface that protrudes from the second reference surface, is disposed inside the opening, faces the main surface exposed from the opening, and has an exposed tip of the optical waveguide facing the optical input / output part on the main surface, and the distance between the connection end surface and the main surface exposed from the opening is 50 μm or less.

[0005] FIG. 1A is a plan view showing an example of an optical communication module to which the optical connection assembly of the present disclosure can be applied. FIG. 1B is a cross-sectional view showing the optical connection assembly of FIG. 1A. FIG. 2 is a perspective view showing the optical connection assembly of FIG. 1. FIG. 3 is a cross-sectional view of the optical connection assembly taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view showing the optical connection assembly of FIG. 3 with some configuration omitted. FIG. 5 is a cross-sectional view showing a state in which a second optical connection part is connected to a first optical connection part. FIG. 6 is a cross-sectional view showing an enlarged main portion of the optical connection assembly of FIG. 3. FIG. 7 is a view showing one step of a mounting method of the present disclosure. FIG. 7B is a view showing a step subsequent to FIG. 7A. FIG. 8A is a view showing a step subsequent to FIG. 7B. FIG. 8B is a view showing a step subsequent to FIG. 8A. FIG. 9 is a cross-sectional view showing an optical connection assembly of Modification 1. FIG. 10 is a cross-sectional view showing an optical connection assembly of Modification 2. FIG. 11A is a cross-sectional view showing an optical connection assembly of Modification 3. FIG. 11B is a cross-sectional view showing a state in which a second optical connection part constituting the optical connection assembly of FIG. 11A is connected to a first optical connection part. Fig. 12A is a cross-sectional view showing an optical connection assembly of Modification 4. Fig. 12B is a cross-sectional view showing a state in which a second optical connecting part constituting the optical connection assembly of Fig. 12A is connected to a first optical connecting part. Fig. 13A is a cross-sectional view showing an optical connection assembly of Modification 5. Fig. 13B is a cross-sectional view showing a state in which a second optical connecting part constituting the optical connection assembly of Fig. 13A is connected to a first optical connecting part.

[0006] [Problem to be Solved by the Present Disclosure] When optically connecting an optical fiber and an optical IC via a lens, as in the optical connection assembly described above, lenses must be provided in both the ferrule and the receptacle, making the configuration of the optical connection assembly complex. Furthermore, when a lens that expands the beam is used, the beam angle dependency on the connection loss increases, so the impact of lens angle misalignment on the connection loss increases. With the recent miniaturization of optical communication modules, when an optical IC substrate is brought close to a communication LSI that becomes hot, the optical connection assembly on the optical IC substrate is exposed to a high-temperature environment caused by the heat of the communication LSI. Therefore, distortion due to the difference in linear thermal expansion coefficient between the ferrule and the optical IC substrate causes lens angle misalignment. As a result, there is a risk of increased connection loss between the optical fiber and the optical IC.

[0007] When optically connecting an optical fiber and an optical IC without a lens, for example, instead of a fitting structure using a guide pin, it is possible to adopt an adhesive structure in which the ferrule is directly fixed to the optical IC substrate using an adhesive. In this case, as described above, when the optical connection assembly is exposed to a high-temperature environment, distortion caused by the difference in the linear thermal expansion coefficient between the ferrule and the optical IC substrate can cause the ferrule to peel off from the optical IC substrate. Such peeling can also cause an increase in connection loss between the optical fiber and the optical IC.

[0008] The present disclosure provides an optical connection assembly and a mounting method that can reduce an increase in connection loss with a simple configuration.

[0009] According to the optical connection assembly and mounting method of the present disclosure, an increase in connection loss can be reduced with a simple configuration.

[0010] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0011] (1) An optical connection assembly according to the present disclosure comprises a first optical connecting component mounted on a main surface of a circuit board including at least one optical input / output unit, and a second optical connecting component including at least one optical waveguide and connected to the first optical connecting component, wherein one of the first optical connecting component and the second optical connecting component has a protrusion, and the other of the first optical connecting component and the second optical connecting component has a hole, and the first optical connecting component and the second optical connecting component form a positioning structure that maintains their relative positions by inserting the protrusion into the hole, the first optical connecting component includes a first reference surface on which the protrusion or the hole is provided, and an opening formed in the first reference surface that exposes the optical input / output unit on the main surface from the first reference surface, the second optical connecting component includes a second reference surface on which the protrusion or the hole is provided and that faces the first reference surface, and a connection end surface that protrudes from the second reference surface, is disposed inside the opening, faces the main surface exposed from the opening, and has an exposed tip of the optical waveguide that faces the optical input / output unit on the main surface, and the distance between the connection end surface and the main surface exposed from the opening is 50 μm or less.

[0012] In the above optical connection assembly, the connection end face protruding from the first reference plane of the first optical connecting component is disposed inside an opening formed in the second reference plane of the second optical connecting component and faces the main surface exposed through the opening. The tip of the optical waveguide exposed from the connection end face faces the optical input / output unit on the main surface. The distance between the connection end face and the main surface of the circuit board exposed through the opening is 50 μm or less. By reducing the distance between the connection end face and the main surface of the circuit board in this manner, the connection loss between the optical waveguide and the optical input / output unit can be sufficiently reduced even when the optical waveguide is directly opposed to the optical input / output unit without a lens. In other words, the optical waveguide and the optical input / output unit can be optically connected with low loss using a simple configuration without using a lens. Furthermore, omitting the lens in this manner can avoid increased connection loss due to angular misalignment of the lens, even in high-temperature environments. Furthermore, when the relative positions of the second optical connecting component and the first optical connecting component on the main surface of the circuit board are maintained by a positioning structure, as in the above optical connection assembly, there is no need to fix the first optical connecting component to the circuit board with an adhesive. Therefore, it is possible to avoid an increase in connection loss due to the first optical connecting part peeling off from the circuit board. Therefore, the optical connection assembly described above makes it possible to reduce an increase in connection loss with a simple configuration.

[0013] (2) In the optical connection assembly described in (1) above, a gap may be formed between the first reference surface and the second reference surface. In order to flatten the connection end surface where the optical waveguide is exposed, the connection end surface may be polished. In this case, a certain amount of error occurs in the amount of polishing of the connection end surface due to manufacturing. In contrast, in the above configuration, a gap is formed between the first reference surface and the second reference surface. In this case, even if an error occurs in the amount of polishing of the connection end surface, the error can be absorbed by the gap. This prevents the first reference surface from abutting against the second reference surface before the connection end surface abuts against the main surface when connecting the second optical connecting part to the first optical connecting part. As a result, the connection end surface can be brought sufficiently close to the main surface, more effectively reducing an increase in connection loss between the optical waveguide and the optical input / output unit.

[0014] (3) In the optical connection assembly described in (2) above, the width of the gap from the first reference surface to the second reference surface may be 20 μm or more and 1 mm or less. When the gap width is 20 μm or more, the gap can more reliably absorb errors in the amount of polishing of the connection end face. Furthermore, when the gap width is 1 mm or less, the insertion length of the protrusion into the hole can be prevented from becoming excessively short. This prevents the relative position of the first optical connecting part and the second optical connecting part, which is maintained by the insertion of the protrusion into the hole, from becoming unstable. Therefore, with the above configuration, the relative position of the first optical connecting part and the second optical connecting part can be more stably maintained, while more effectively reducing an increase in connection loss between the optical waveguide and the optical input / output part.

[0015] (4) In the optical connection assembly described in any one of (1) to (3), the distance from the second reference surface to the connection end face may be longer than the distance from the first reference surface to the main surface. In this case, even if an error occurs in the amount of polishing of the connection end face, when connecting the second optical connecting part to the first optical connecting part, the first reference surface can be prevented from abutting on the second reference surface before the connection end face abuts on the main surface. As a result, the connection end face can be brought sufficiently close to the main surface, which more effectively reduces an increase in connection loss between the optical waveguide and the optical input / output unit.

[0016] (5) In the optical connection assembly according to any one of (1) to (4), the second optical connection part has a thickness of 0.5×10 －５ [ / K] or more and 5 × 10 －５ [ / K] or less. In this case, even if a material such as a glass material or a metal material is selected as the material for the first optical connecting part, the difference in the linear thermal expansion coefficient of the second optical connecting part relative to the linear thermal expansion coefficient of such a material can be made small. This makes it possible to reduce the occurrence of large positional deviations between the first optical connecting part and the second optical connecting part due to thermal stress caused by the difference in the linear thermal expansion coefficient of the first optical connecting part and the linear thermal expansion coefficient of the second optical connecting part. Note that an example of a resin material for the second optical connecting part is, for example, a resin material having a linear thermal expansion coefficient of 1×10 －５ LCP (liquid crystal polymer) having a linear thermal expansion coefficient of 2.5 × 10 －５ Examples of suitable materials include PPS (polyphenylene sulfide) having a linear thermal expansion coefficient of 0.1 to 1.0 [ / K] or less.

[0017] (6) In the optical connection assembly described in any one of (1) to (5) above, the connection end surface may be provided with an anti-reflection film that prevents light reflection at the connection end surface. When the tip of the optical waveguide exposed from the connection end surface of the second optical connection component is directly opposed to the optical input / output portion of the circuit board without the use of other components such as a lens or adhesive, manufacturing errors may cause the tip of the optical waveguide to not completely abut the optical input / output portion, resulting in a gap between the tip of the optical waveguide and the optical input / output portion. The presence of such a gap can cause problems with reflected backlight between the optical waveguide and the optical input / output portion. In contrast, when an anti-reflection film is provided on the connection end surface, even if a gap is formed between the tip of the optical waveguide and the optical input / output portion, the reflected backlight between the optical waveguide and the optical input / output portion can be effectively reduced, thereby reducing the degradation of optical characteristics caused by the reflected backlight.

[0018] (7) In the optical connection assembly described in any one of (1) to (6) above, a spacer may be disposed between the connection end face and the main surface exposed from the opening, and the spacer may have a thickness of 1 μm or more and 20 μm or less. In this case, by abutting the spacer against the connection end face of the second optical connection component and the main surface of the circuit board, the distance between the connection end face and the main surface can be maintained at 1 μm or more and 20 μm or less. By having a spacer thickness of 20 μm or less, the distance between the connection end face and the main surface can be further shortened. As a result, the connection loss between the optical waveguide exposed from the connection end face and the optical input / output portion on the main surface can be more effectively reduced. Furthermore, when a spacer is provided between the connection end face and the main surface in this manner, a gap can be formed between the optical waveguide and the optical input / output portion. In this case, unlike when the optical waveguide directly abuts against the optical input / output portion, foreign matter such as dust that may be present between the optical waveguide and the optical input / output portion can be prevented from being crushed by the optical waveguide and covering the optical waveguide. As a result, it is possible to avoid an increase in connection loss between the optical waveguide and the optical input / output section due to foreign matter.

[0019] (8) In the optical connection assembly according to any one of (1) to (7), the first optical connection part has a thickness of 1×10 －６ [ / K] or more and 7 x 10 －６ The first optical connecting part may be formed of a metal material having a linear thermal expansion coefficient of 1×10 [ / K] or less. By selecting a metal material as the material of the first optical connecting part in this way, it is possible to reduce the occurrence of damage to the first optical connecting part when inserting the protrusion into the hole. －６ [ / K] or more and 7 x 10 －６ A linear thermal expansion coefficient of 5×10 [ / K] or less is close to the linear thermal expansion coefficient of the material (e.g., silicon) constituting the circuit board on which the first optical connecting part is mounted, so even when the optical connecting assembly is used in a high-temperature environment, it is possible to reduce the occurrence of damage to the first optical connecting part due to thermal stress caused by the difference between the linear thermal expansion coefficient of the first optical connecting part and the linear thermal expansion coefficient of the circuit board. －６ Kovar having a linear thermal expansion coefficient of 2×10 －６ Examples of the material include Invar having a linear thermal expansion coefficient of 0.1 to 1.0 K or less.

[0020] (9) In the optical connection assembly described in any one of (1) to (7) above, the first optical connection component may be formed of a glass material. Glass materials have heat resistance and a small linear thermal expansion coefficient, even in high-temperature environments of 85°C or higher, which is difficult for resins commonly used in optical connectors, such as PPS (Poly Phenylene Sulfide) and PEI (Poly Ether Imide). Therefore, the use of glass components is expected to expand as components for connecting optical waveguides to circuit boards located near heat-generating semiconductors, such as ASICs (Application Specific Integrated Circuits), which are becoming increasingly practical in the future. Furthermore, since the linear thermal expansion coefficient of glass materials is close to that of the material (e.g., silicon) constituting the circuit board, even when the optical connection assembly is used in a high-temperature environment, damage to the first optical connection component due to thermal stress caused by the difference between the linear thermal expansion coefficient of the first optical connection component and the linear thermal expansion coefficient of the circuit board can be reduced. Furthermore, using a glass material that is transparent to ultraviolet light allows the first optical connection component to be easily fixed to the main surface of the circuit board using an ultraviolet-curable adhesive.

[0021] (10) In the optical connection assembly described in (9) above, the protrusion may be a guide pin fixed to the first optical connecting component while inserted into a guide hole formed in the first reference surface. The gap between the outer surface of the guide pin and the inner surface of the guide hole may be 2 μm or less. The guide pin may be formed of a material having a linear thermal expansion coefficient of 10 times or less than that of the glass material of the first optical connecting component. By providing a gap of 2 μm or less between the inner surface of the guide hole of the first optical connecting component and the outer surface of the guide pin, even if the guide pin thermally expands in a high-temperature environment, the thermal expansion of the guide pin can be absorbed by the gap. As a result, damage to the first optical connecting component caused by the thermally expanded guide pin can be reduced. Furthermore, by using a material for the guide pin with a linear thermal expansion coefficient of 10 times or less than that of the glass material, damage to the first optical connecting component caused by thermal stress resulting from the difference between the linear thermal expansion coefficient of the first optical connecting component and that of the guide pin can be reduced even when the optical connection assembly is used in a high-temperature environment.

[0022] (11) In the optical connection assembly described in (10) above, a coating layer formed of a resin material may be provided on the inner surface of the guide hole. Because the glass material of the first optical connecting component is a brittle material, it is expected that chipping may occur in the first optical connecting component when a protrusion is inserted into the hole, or that excessive force may be applied from the second optical connecting component to the first optical connecting component, causing the first optical connecting component to break. In contrast, in the above configuration, a coating layer is formed on the inner surface of the guide hole of the first optical connecting component. This reduces chipping and breakage of the first optical connecting component when a protrusion is inserted into the hole. Furthermore, by partially forming a coating layer on the glass first optical connecting component, the heat resistance of the glass material of the first optical connecting component can be utilized while the coating layer reinforces the parts of the first optical connecting component that are prone to problems.

[0023] (12) In the optical connection assembly described in any one of (1) to (11) above, the hole may be provided on the second reference plane, the optical waveguide may be constituted by an optical fiber held in the second optical connecting component, and a fiber insertion hole into which the optical fiber is inserted may be formed in the connection end face, and the fiber insertion hole may extend parallel to the hole. If the fiber insertion hole extends obliquely relative to the hole, depending on the amount of polishing, there is a possibility that the opening position of the fiber insertion hole on the connection end face and the opening position of the hole may be significantly misaligned, depending on the amount of polishing, during polishing. In contrast, if the fiber insertion hole extends parallel to the hole, significant misalignment between the opening position of the fiber insertion hole and the opening position of the hole due to polishing can be prevented. This reduces a decrease in the positioning accuracy of the optical fiber caused by misalignment between the opening position of the fiber insertion hole and the opening position of the hole.

[0024] (13) In the optical connection assembly according to any one of (1) to (12), the positioning structure may include a pair of protrusions provided on the first reference surface and a pair of holes provided on the second reference surface. The relationship of formula (1) may be established when the linear thermal expansion coefficient of the first optical connection part is C1 [ / K], the linear thermal expansion coefficient of the second optical connection part is C2 [ / K], the distance between the centers of the pair of holes at room temperature is L1 [mm], and the ambient temperature is T [K]. By selecting the material and size of the first optical connecting part, the material and size of the second optical connecting part, and the temperature range of the ambient temperature so as to satisfy the relationship of the above formula (1), even if the first optical connecting part and the second optical connecting part thermally expand in a high-temperature environment, the positional deviation of the optical waveguide relative to the optical input / output part can be kept within an acceptable range.

[0025] (14) In the optical connection assembly according to any one of (1) to (13), the positioning structure may include a pair of protrusions provided on the first reference surface and a pair of holes provided on the second reference surface. The pair of protrusions may be configured by a pair of guide pins fixed to the first optical connecting component while being inserted into a pair of guide holes formed on the first reference surface. The relationship of Equation (2) may be established when the linear thermal expansion coefficient of the first optical connecting component is C1 [ / K], the linear thermal expansion coefficient of the second optical connecting component is C2 [ / K], the distance between the centers of the pair of holes at room temperature is L1 [mm], the distance between the centers of the pair of guide holes at room temperature is L2 [mm], and the ambient temperature is T [K]. By selecting the material and size of the first optical connecting part, the material and size of the second optical connecting part, and the temperature range of the environmental temperature so as to satisfy the relationship of the above formula (2), even if the first optical connecting part and the second optical connecting part thermally expand in a high-temperature environment, the positional deviation of the optical waveguide with respect to the optical input / output part can be kept within an allowable range. Furthermore, in this case, even if a difference in thermal expansion occurs between the first optical connecting part and the second optical connecting part, damage to one or both of the first optical connecting part and the second optical connecting part due to the difference in thermal expansion can be reduced.

[0026] (15) The optical connection assembly described in any one of (1) to (14) above may further include a clip member that grips the first optical connecting component and the second optical connecting component. The clip member may include a base portion arranged to face the first reference surface of the first optical connecting component via the second optical connecting component, a pair of arms extending from the base portion through the outside of the second optical connecting component to positions facing the pair of side surfaces of the first optical connecting component, and a pair of hooks that protrude from the pair of arms toward the pair of side surfaces. A pair of step portions with which the pair of hooks engage may be formed on the pair of side surfaces. In this case, by providing a clip member that grips the first optical connecting component and the second optical connecting component in case the protrusions come out of the holes, it is possible to stably maintain the connection state between the first optical connecting component and the second optical connecting component.

[0027] (16) The mounting method of the present disclosure is a mounting method for mounting a first optical connecting component included in an optical connection assembly described in any one of (1) to (15) above on a main surface of a circuit board, and includes the steps of: preparing a first wafer on which a plurality of first optical connecting components arranged two-dimensionally are formed; and preparing a second wafer on which a plurality of circuit boards arranged two-dimensionally are formed; positioning the first wafer relative to the second wafer so that a plurality of first optical connecting components overlap each of the plurality of circuit boards; bonding the first wafer to the second wafer while the first wafer is positioned relative to the second wafer; and cutting the first wafer and the second wafer into individual pieces to form a plurality of first optical connecting components with circuit boards.

[0028] In the above mounting method, unlike when the first wafer and the second wafer are individually divided and each first optical connecting component is aligned with each circuit board, by positioning the first wafer with respect to the second wafer, it is possible to align each first optical connecting component with each circuit board all at once. In other words, in the above mounting method, aligning the first optical connecting component with one circuit board once can align the first optical connecting components with all circuit boards, so the number of alignment steps can be reduced to one compared to when alignment work is performed for each circuit board. Therefore, the above mounting method can simplify the mounting step of the first optical connecting components.

[0029] [Details of the embodiments of the present disclosure] Specific examples of the optical connection assembly and mounting method of the present disclosure will be described in detail below with reference to the accompanying drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the description of the drawings, the same elements are given the same reference numerals, and duplicate explanations will be omitted as appropriate.

[0030] FIG. 1A is a plan view showing an example of an optical communications module 10 to which the optical connection assembly 100 of the present embodiment can be applied. FIG. 1B is a cross-sectional view showing the optical communications module 10. For convenience, the portion of FIG. 1A showing the optical connection assembly 100 is hatched. The optical communications module 10 performs optical communications via multiple optical fibers 500 (optical waveguides). The optical communications module 10 includes, for example, a communication LSI 20, multiple optical IC boards 30 (circuit boards), and multiple optical connection assemblies 100. The optical communications module 10 has a structure in which, for example, the communication LSI 20 and the multiple optical IC boards 30 are mounted on the same substrate 50. Each optical IC board 30 is connected to the communication LSI 20 via electrical wiring 40. The substrate 50 is, for example, an interposer substrate. The electrical wiring 40 passes through, for example, the interior of the substrate 50, connecting the optical IC boards 30 and the communication LSI 20. The electrical wiring 40 may connect the optical IC substrate 30 and the communication LSI 20 through the surface layer of the substrate 50. Each optical connection assembly 100 is detachably attached to the optical IC substrate 30 in order to optically connect an optical input / output unit 31 (see FIG. 3 described later) provided on the optical IC substrate 30 to an optical fiber 500.

[0031] In addition, miniaturization of the optical communications module 10 is required to realize efficient use of storage space. As the optical communications module 10 becomes smaller, the optical IC substrate 30 approaches the communication LSI 20, which becomes hot, as shown in FIGS. 1A and 1B. As a result, the optical connection assembly 100 on the optical IC substrate 30 is exposed to a high-temperature environment (e.g., 85°C or higher) caused by the heat generated by the communication LSI 20. The optical communications module 10 of this embodiment is designed assuming use in such a high-temperature environment.

[0032] FIG. 2 is a perspective view showing the optical connection assembly 100. FIG. 3 is a cross-sectional view of the optical connection assembly taken along line III-III in FIG. 2. As shown in FIGS. 2 and 3, the optical connection assembly 100 includes, for example, a first optical connecting part 110 and a second optical connecting part 120. In the optical connection assembly 100, the first optical connecting part 110 is placed on the main surface 30a of the optical IC substrate 30, and the second optical connecting part 120 is disposed in a position facing the first optical connecting part 110 in the vertical direction. The first optical connecting part 110 and the second optical connecting part 120 are positioned relative to each other while facing each other in the vertical direction, and are connected along the vertical direction.

[0033] 3, each optical fiber 500 held in the second optical connecting part 120 is optically connected to each optical input / output unit 31 of the optical IC board 30 via the first optical connecting part 110. The first optical connecting part 110 and the second optical connecting part 120 may be positioned relative to each other while facing each other in the horizontal direction, or may be connected along the horizontal direction.

[0034] The optical fiber 500 held by the second optical connecting part 120 is preferably an optical fiber with low bending loss (hereinafter referred to as "low bending loss fiber") so that it can accommodate flexible bending shapes. In other words, the optical fiber 500 is preferably one that has bending loss characteristics conforming to ITU-T International Standard G.657.B3. The optical fiber 500 may have bending loss characteristics lower than those conforming to the above standard. An optical fiber with an enhanced light confinement function in the core is suitable as a low bending loss fiber. A low bending loss fiber is realized, for example, by a structure in which the refractive index of the core is higher than that of the core in a typical optical fiber, or by a refractive index structure in which a trench layer with a refractive index lower than that of the cladding is provided between the core and the cladding. A jacket layer is usually provided around the cladding to maintain the fiber outer diameter conforming to the above standard.

[0035] The composition of the optical fiber 500 can be realized by adding a dopant to silica glass to appropriately control the refractive index. As an example, the optical fiber 500 can be made of germanium dioxide (GeO ２The optical fiber 500 includes a central core mainly composed of silica glass doped with GeO, a cladding composed of pure silica glass or a cladding composed mainly of silica glass doped with fluorine (F), and a jacket layer composed of pure silica glass. This fiber composition makes it possible to obtain an optical fiber 500 that is economical and has good shape controllability. The jacket layer may or may not contain chlorine (Cl). The central core is composed of GeO. ２ and F may be co-doped. In order to increase the strength of optical fiber 500, a combination of methods may be used in the manufacturing stage of optical fiber 500, such as a method of applying a carbon coating to the outer periphery of the glass portion, or a method of applying compressive strain to the outer periphery of the glass portion by adjusting the thermal history during drawing.

[0036] 2, the optical fiber 500 is provided with a preheated bent portion. Heating means for forming the bent portion include a burner, a CO ２ Laser, arc discharge, and heater are applicable. ２ The laser allows for easy adjustment of irradiation intensity, irradiation range, and irradiation time, making it possible to precisely control the curvature distribution at the bent portion. ２ At the typical laser wavelength of around 10 μm, glass materials are opaque, so CO ２ It is believed that the laser irradiation energy is absorbed by the surface layer of the glass material and transmitted by re-radiation and thermal conduction. ２ If the laser power is too high, the surface temperature of the glass material will rise sharply to the glass evaporation temperature, making it impossible to maintain the shape of the glass component. ２ The laser irradiation power is appropriately adjusted so that the surface layer of the glass material does not evaporate, and the temperature inside the glass in the heated region rises to a temperature equal to or higher than the working point for a certain period of time, thereby removing strain inside the glass. －４ °C / sec or less is suitable.

[0037] The first optical connecting part 110 functions as an adapter for connecting the optical IC board 30 and the second optical connecting part 120. The first optical connecting part 110 is fixed to the main surface 30a of the optical IC board 30 by, for example, an ultraviolet-curing adhesive. The first optical connecting part 110 is, for example, a glass substrate made of a glass material. Such a glass first optical connecting part 110 is capable of transmitting ultraviolet light. Being capable of transmitting ultraviolet light means, for example, that when a material with a plate thickness of 10 mm is irradiated with ultraviolet light having a wavelength of 320 nm or more and 400 nm or less, the transmittance of ultraviolet light is 10% or more. The transmittance of ultraviolet light may be 50% or more. The glass material of the first optical connecting part 110 is, for example, 0.3×10 －６ [ / K] or more and 5 × 10 －６ [ / K] or less. Examples of the glass material of the first optical connecting part 110 include borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass.

[0038] In the following description, the normal direction to the surface 110a (first reference plane) of the first optical connecting part 110 is referred to as the Z-axis direction, and the directions along the surface 110a are referred to as the X-axis direction and the Y-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are, for example, perpendicular to each other. The first optical connecting part 110 is, for example, a rectangular plate with the Y-axis direction as the longitudinal direction, the X-axis direction as the lateral direction, and the Z-axis direction as the thickness direction.

[0039] The front surface 110a and the back surface 110b of the first optical connecting part 110 are flat surfaces along the X-axis direction and the Y-axis direction, and are aligned parallel to the Z-axis direction. The back surface 110b is in contact with the main surface 30a of the optical IC substrate 30. The main surface 30a of the optical IC substrate 30 is, for example, arranged parallel to the front surface 110a and the back surface 110b. The front surface 110a faces the opposite side to the main surface 30a and faces the second optical connecting part 120. The distance d1 in the Z-axis direction between the front surface 110a and the main surface 30a corresponds to the thickness of the first optical connecting part 110 (i.e., the distance in the Z-axis direction between the front surface 110a and the back surface 110b). The distance d1 is, for example, 0.01 mm or more and 1.00 mm or less.

[0040] An opening 110c is formed on the front surface 110a of the first optical connecting part 110. The opening 110c penetrates in the Z-axis direction from the front surface 110a to the back surface 110b, exposing the plurality of optical input / output units 31 mounted on the main surface 30a. The opening 110c defines a space for propagating optical signals between the plurality of optical input / output units 31 and the plurality of optical fibers 500. As shown in Fig. 2, the shape of the opening 110c as viewed along the Z-axis direction is, for example, rectangular with the Y-axis direction as the longitudinal direction and the X-axis direction as the lateral direction.

[0041] Furthermore, a pair of guide holes 110d are formed on the surface 110a of the first optical connecting part 110. The pair of guide holes 110d are through holes that penetrate in the Z-axis direction from the surface 110a to the back surface 110b at positions sandwiching the opening 110c in the Y-axis direction. The shape of each of the pair of guide holes 110d as viewed along the Z-axis direction is, for example, circular. A pair of guide pins 150 corresponding to each of the pair of guide holes 110d are inserted into the pair of guide holes 110d. The guide holes 110d may have any shape as long as they can maintain a space that accommodates a portion of the guide pin 150, and therefore may be not limited to through holes but may have other shapes, such as a recess or a groove.

[0042] Each of the pair of guide pins 150 has, for example, a cylindrical shape extending in the Z-axis direction. A portion of the guide pin 150 is inserted into the guide hole 110d and adhesively fixed to the inner surface of the guide hole 110d. The remaining portion of the guide pin 150 protrudes in the Z-axis direction from the surface 110a. Therefore, in this embodiment, of the guide pin 150 partially housed in the guide hole 110d, the exposed portion that protrudes from the guide hole 110d is configured as an example of a "protrusion" in the present disclosure.

[0043] In FIG. 3 , the difference (D1-D2) between the outer diameter D1 of the guide pin 150 and the inner diameter D2 of the guide hole 110d, i.e., the gap between the outer surface of the guide pin 150 and the inner surface of the guide hole 110d, may be, for example, 2 μm or less, or may be 1 μm or less. The gap between the outer surface of the guide pin 150 and the inner surface of the guide hole 110d is filled with adhesive. The guide pin 150 is fixed to the inner surface of the guide hole 110d by adhesive. A heat-resistant adhesive is suitable as the adhesive for fixing the guide pin 150, as it is intended for use in a high-temperature environment. Note that the adhesive for fixing the guide pin 150 is omitted from the illustration in FIG. 3 .

[0044] The material of the guide pin 150 may be any material having a linear thermal expansion coefficient that is 10 times or less the linear thermal expansion coefficient of the glass material of the first optical connecting part 110. If the guide pin 150, which has a linear thermal expansion coefficient that is significantly different from that of the glass material, is inserted into the guide hole 110d and adhesively fixed, thermal stress will be generated in a high-temperature environment due to the difference in linear thermal expansion coefficient between the guide pin 150 and the first optical connecting part 110. As a result, there is a risk of damage to the first optical connecting part 110. Therefore, by selecting a material for the guide pin 150 having a linear thermal expansion coefficient that is 10 times or less the linear thermal expansion coefficient of the glass material, damage to the first optical connecting part 110 due to thermal stress can be reduced.

[0045] The second optical connecting part 120 is attached to the tip of the optical fiber 500. The second optical connecting part 120 is connected to the first optical connecting part 110 mounted on the optical IC board 30. In other words, the second optical connecting part 120 is connected to the optical IC board 30 via the first optical connecting part 110. The second optical connecting part 120 is, for example, a ferrule made of a resin material. The resin material of the second optical connecting part 120 is, for example, 0.5×10 －５ [ / K] or more and 5 × 10 －５ The resin material for the second optical connecting part 120 is selected to have a linear thermal expansion coefficient of 1×10 [ / K] or less. －５ and a liquid crystal polymer having a linear thermal expansion coefficient of 2.5 × 10 －５ Examples of suitable PPS include PPS having a linear thermal expansion coefficient of 0.1 to 1.0 K or less.

[0046] The second optical connecting part 120 may be a glass substrate in which a plurality of optical fibers 500 are embedded. Alternatively, the second optical connecting part 120 may be a glass substrate in which a plurality of refractive index change regions (optical waveguides) are formed by laser drawing. As the glass substrate in which the plurality of optical fibers 500 are embedded, for example, a porous glass substrate having a plurality of through holes into which the plurality of optical fibers 500 are respectively inserted may be used.

[0047] Such through holes are formed, for example, by a process combining photolithography and dry etching such as RIE, or by a laser-based drilling technique. However, any glass drilling technique can be used as long as the through hole position has an error of 1 μm or less from the predetermined design position and the inner diameter of the through hole can be within ±1 μm of the target inner diameter. The through holes provided in the glass substrate for inserting optical fibers do not need to be perpendicular to the surface of the glass substrate. For example, by forming the through holes at an angle of, for example, 8 degrees with respect to the perpendicular to the surface of the glass substrate, reflected back light can be effectively reduced.

[0048] The second optical connecting part 120 includes, for example, a connecting end face 120a where the tip of the optical fiber 500 is exposed, and a stepped face 120b (second reference plane) recessed from the connecting end face in the Z-axis direction. The connecting end face 120a and the stepped face 120b are, for example, flat faces along the X-axis direction and the Y-axis direction. The connecting end face 120a may include an inclined face tilted at 8 degrees with respect to the XY plane. When the second optical connecting part 120 is viewed along the Z-axis direction, for example, the connecting end face 120a is located at the center of the second optical connecting part 120 and has a rectangular shape. The stepped face 120b has a rectangular ring shape surrounding the connecting end face 120a. The stepped face 120b faces the surface 110a of the first optical connecting part 110 in the Z-axis direction. The connecting end face 120a protrudes from the stepped face 120b in the Z-axis direction and is disposed inside an opening 110c formed in the surface 110a. The connection end surface 120a faces the main surface 30a of the optical IC substrate 30 in the Z-axis direction.

[0049] As shown in Fig. 3, the connection end face 120a of the second optical connecting part 120 has a plurality of fiber insertion holes 120c formed therein, into which a plurality of optical fibers 500 are respectively inserted. The plurality of fiber insertion holes 120c extend from the connection end face 120a along the Z-axis direction and are aligned along the Y-axis direction. Each fiber insertion hole 120c viewed along the Z-axis direction has, for example, a circular shape. The tip of each optical fiber 500 inserted into each fiber insertion hole 120c is exposed from the connection end face 120a. The tip of each optical fiber 500 faces, in the Z-axis direction, each optical input / output unit 31 on the main surface 30a exposed from the opening 110c.

[0050] The connection end face 120a may be in contact with the main surface 30a or may be spaced apart from the main surface 30a in the Z-axis direction. Therefore, the tip of each optical fiber 500 exposed from the connection end face 120a may also be in contact with each optical input / output unit 31 on the main surface 30a or may be spaced apart from each optical input / output unit 31 in the Z-axis direction. This embodiment illustrates a case in which the connection end face 120a is spaced apart from the main surface 30a, and a small gap is formed between the connection end face 120a and the main surface 30a. In this case, each optical fiber 500 is optically connected to each optical input / output unit 31 via the gap. The distance G1 in the Z-axis direction between the connection end face 120a and the main surface 30a exposed through the opening 110c is, for example, 0 μm or more and 50 μm or less. The distance G1 may be, for example, 0 μm or more and 20 μm or less.

[0051] The step surface 120b of the second optical connecting part 120 is separated from the surface 110a of the first optical connecting part 110, for example, in the Z-axis direction. That is, a gap is formed between the step surface 120b and the surface 110a in the Z-axis direction. The width of the gap from the step surface 120b to the surface 110a, i.e., the distance G2 in the Z-axis direction between the step surface 120b and the surface 110a, is, for example, 20 μm or more and 1 mm or less. The protruding length of the connecting end surface 120a from the step surface 120b in the Z-axis direction is longer than the thickness of the first optical connecting part 110 in the Z-axis direction. The protruding length of the connecting end surface 120a from the step surface 120b is represented by the distance d2 in the Z-axis direction from the step surface 120b to the connecting end surface 120a. As described above, the thickness of the first optical connecting part 110 is represented by the distance d1 in the Z-axis direction from the surface 110a to the main surface 30a. In this case, d2 is greater than d1. That is, by setting the distance d2 to be greater than the distance d1, the gap between the step surface 120b and the surface 110a is maintained.

[0052] A pair of guide holes 120d are formed in the step surface 120b of the second optical connecting part 120. The pair of guide holes 120d are arranged at positions that overlap in the Z-axis direction with the pair of guide holes 110d formed in the surface 110a of the first optical connecting part 110. Each of the pair of guide holes 120d is a through-hole that penetrates the second optical connecting part 120 in the Z-axis direction. The shape of the guide hole 120d as viewed along the Z-axis direction is, for example, circular. The inner diameter D3 of the guide hole 120d is, for example, the same as the inner diameter D2 of the guide hole 110d.

[0053] The exposed portion of the guide pin 150 protruding from the surface 110a of the first optical connecting part 110 is inserted into the guide hole 120d. Therefore, in this embodiment, the guide hole 120d is configured as an example of a "hole" of the present disclosure into which the exposed portion of the guide pin 150 as a protrusion is inserted. The guide hole 120d may have any shape as long as it can maintain a space for accommodating a portion of the guide pin 150. Therefore, the guide hole 120d is not limited to a through hole, and may have other shapes, such as a recess or a groove.

[0054] 4 is a cross-sectional view of the optical connection assembly 100 of FIG. 3 , omitting the guide pin 150 and the optical fiber 500. As shown in FIG. 4 , the central axis CL2 of the guide hole 110d is located on an extension of the central axis CL1 of the guide hole 120d. In other words, when viewed along the Z-axis direction, the central axis CL1 coincides with the central axis CL2. Therefore, the distance L1 in the Y-axis direction between the central axes CL1 of the pair of guide holes 120d is the same as, for example, the distance L2 in the Y-axis direction between the central axes CL2 of the pair of guide holes 110d.

[0055] If the linear thermal expansion coefficient of the material constituting the first optical connecting part 110 is C1 [ / K], the linear thermal expansion coefficient of the material constituting the second optical connecting part 120 is C2 [ / K], and the ambient temperature is T [K], the relationship of the above-mentioned formula (1) holds between the linear thermal expansion coefficient C1 [ / K], the linear thermal expansion coefficient C2 [ / K], the ambient temperature T [K], and the distance L1 [mm]. Furthermore, the relationship of the above-mentioned formula (2) holds between the linear thermal expansion coefficient C1 [ / K], the linear thermal expansion coefficient C2 [ / K], the ambient temperature T [K], the distance L1 [mm], and the distance L2 [mm]. Note that the distances L1 and L2 are values ​​in a room temperature environment.

[0056] Equation (1) indicates the upper limit of the deviation of the distance L1 when the first optical connecting part 110 and the second optical connecting part 120 thermally expand due to a temperature change, using the distance L1 between the pair of guide holes 120d at room temperature as a reference. In other words, equation (1) indicates that the deviation of the distance L1 at ambient temperature T from the distance L1 at room temperature is less than 0.01. Equation (2) indicates the upper and lower limits of the deviation of the distances L1, L2 when the first optical connecting part 110 and the second optical connecting part 120 thermally expand due to a temperature change, using the distance L1 between the pair of guide holes 120d at room temperature and the distance L2 between the pair of guide holes 110d as a reference. In other words, equation (2) indicates that the deviation of the distances L1, L2 at ambient temperature T from the distances L1, L2 at room temperature is greater than −0.005 and less than 0.005.

[0057] By selecting the material and size of the first optical connecting part 110, the material and size of the second optical connecting part 120, and the temperature range of the environmental temperature so as to satisfy formula (1) and formula (2), it is possible to keep the misalignment between the materials of the first optical connecting part 110 and the second optical connecting part 120 within an allowable range. For example, when the material of the first optical connecting part 110 is Tempax (registered trademark) glass, the material of the second optical connecting part 120 is PPS (polyphenylene sulfide), and the environmental temperature T is 25°C or higher and 85°C or lower, formula (1) and formula (2) can be satisfied. The linear thermal expansion coefficient C1 of the first optical connecting part 110 is 3.25 × 10 －６ [ / K], and the linear thermal expansion coefficient C2 of the second optical connecting part 120 is 2×10 －５ [ / K].

[0058] 4, the fiber insertion holes 120c extend, for example, parallel to the guide hole 120d. That is, the central axes CL3 of the fiber insertion holes 120c are parallel to the central axis CL1 of the guide hole 120d. For example, the central axes CL3 and CL1 both extend in the Z-axis direction. The central axes CL3 of the fiber insertion holes 120c are perpendicular to the splicing end face 120a, for example. The fiber insertion holes 120c do not necessarily need to be perpendicular to the splicing end face 120a; for example, they may be tilted at an angle of 8 degrees relative to the splicing end face 120a.

[0059] 5 is a cross-sectional view showing a state in which the second optical connecting part 120 is connected to the first optical connecting part 110. As shown in Fig. 5, when connecting the second optical connecting part 120 to the first optical connecting part 110, the second optical connecting part 120 is brought closer to the first optical connecting part 110 in the Z-axis direction so that exposed portions of the pair of guide pins 150 adhesively fixed to the pair of guide holes 110d of the first optical connecting part 110 are inserted into the pair of guide holes 120d of the second optical connecting part 120.

[0060] By inserting the exposed portions of the pair of guide pins 150 corresponding to the pair of guide holes 120d of the second optical connecting part 120 into the pair of guide holes 120d, the second optical connecting part 120 is positioned in a state facing the first optical connecting part 110 in the Z-axis direction. In this state, the connection end surface 120a of the second optical connecting part 120 faces the main surface 30a exposed from the opening 110c of the first optical connecting part 110 in the Z-axis direction, and the step surface 120b of the second optical connecting part 120 faces the surface 110a of the first optical connecting part 110 in the Z-axis direction.

[0061] Thereafter, the second optical connecting part 120 is moved toward the first optical connecting part 110 in the Z-axis direction along the pair of guide pins 150 until the connection end face 120a of the second optical connecting part 120 abuts against the main surface 30a of the optical IC substrate 30 in the Z-axis direction, or until the step surface 120b of the second optical connecting part 120 abuts against the surface 110a of the first optical connecting part 110 in the Z-axis direction. For example, with the pair of guide pins 150 inserted into the pair of guide holes 120d, the second optical connecting part 120 may be moved toward the first optical connecting part 110 until the connection end face 120a abuts against the main surface 30a.

[0062] As a result, as shown in Figure 3, the distance G1 between the connection end face 120a and the main surface 30a is 0 μm or more and 50 μm or less. The distance G2 between the step surface 120b and the surface 110a is, for example, 20 μm or more and 1 mm or less. The tips of the optical fibers 500 exposed from the connection end face 120a face in the Z-axis direction to the optical input / output units 31 on the main surface 30a exposed from the opening 110c, and are optically connected to the optical input / output units 31. In this way, an optical connection assembly 100 is obtained in which the second optical connecting part 120 is connected to the first optical connecting part 110.

[0063] As described above, in the present embodiment, the first optical connecting part 110 and the second optical connecting part 120 are positioned relative to each other by inserting the exposed portions of the pair of guide pins 150 protruding from the pair of guide holes 110d of the first optical connecting part 110 into the pair of guide holes 120d of the second optical connecting part 120. Therefore, the exposed portions of the pair of guide pins 150 protruding from the pair of guide holes 110d of the first optical connecting part 110 and the pair of guide holes 120d of the second optical connecting part 120 constitute a positioning structure M (see FIGS. 2 and 3 ) for maintaining the relative positions of the first optical connecting part 110 and the second optical connecting part 120.

[0064] FIG. 6 is a cross-sectional view showing the vicinity of the tip of the optical fiber 500 of the optical connection assembly 100 of FIG. 3 . As shown in FIG. 6 , the tip of the optical fiber 500 directly faces the optical input / output unit 31 on the main surface 30 a without any other structure such as a lens or adhesive. Therefore, if the distance G1 between the connection end face 120 a and the main surface 30 a is too large, the beam B emitted from the optical fiber 500 will diverge significantly before reaching the optical input / output unit 31. As a result, there is a concern that the connection loss between the optical fiber 500 and the optical input / output unit 31 will increase. In contrast, if the distance G1 is set to 50 μm or less, the divergence of the beam B between the optical fiber 500 and the optical input / output unit 31 can be sufficiently suppressed. In this case, the connection loss between the optical fiber 500 and the optical input / output unit 31 can be kept within an acceptable range, such as about 1 dB. Therefore, the optical connection assembly 100 can achieve a connection between the optical fiber 500 and the optical input / output unit 31 with low connection loss.

[0065] Next, an example of a mounting method for the first optical connecting part 110 constituting the optical connection assembly 100 will be described with reference to Figures 7A, 7B, 8A, and 8B. Figure 7A is a diagram showing one step of the mounting method for the first optical connecting part 110. Figure 7B is a diagram showing a step subsequent to Figure 7A. Figure 8A is a diagram showing a step subsequent to Figure 7B. Figure 8B is a diagram showing a step subsequent to Figure 8A.

[0066] First, as shown in Fig. 7A, an adapter wafer 11 (first wafer) is prepared, on which a plurality of first optical connecting parts 110 serving as adapters are formed. An optical IC wafer 3 (second wafer) is also prepared, on which a plurality of optical IC substrates 30 are formed. In the adapter wafer 11, the plurality of first optical connecting parts 110 are two-dimensionally arranged along the X-axis direction and the Y-axis direction. When viewed along the Z-axis direction, the adapter wafer 11 has a circular shape with a notch 11a in part of it.

[0067] Then, the adapter wafer 11 is superimposed in the Z-axis direction on an optical IC wafer 3 on which a plurality of optical IC substrates 30 (see, for example, FIGS. 1A and 1B) are formed. In the optical IC wafer 3, the plurality of optical IC substrates 30 are arranged two-dimensionally along the X-axis direction and the Y-axis direction so as to correspond to the arrangement of the plurality of first optical connecting parts 110. When viewed along the Z-axis direction, the optical IC wafer 3 has a circular shape with a notch 3a in part of it.

[0068] The notch 3a in the optical IC wafer 3 and the notch 11a in the adapter wafer 11 serve as positioning references for determining the position of the adapter wafer 11 relative to the optical IC wafer 3. Therefore, the adapter wafer 11 is positioned relative to the optical IC wafer 3 by overlapping the adapter wafer 11 on the optical IC wafer 3 so that the notch 11a coincides with the notch 3a when viewed in the Z-axis direction. In this state, the multiple optical input / output units 31 of each optical IC substrate 30 are exposed from the opening 110c of each first optical connecting part 110.

[0069] 7B , with the optical IC wafer 3 and the adapter wafer 11 aligned, each first optical connecting part 110 and each optical IC board 30 are aligned. Specifically, a second optical connecting part 120 holding a plurality of optical fibers 500 is connected to one of the first optical connecting parts 110. Then, the position of the adapter wafer 11 relative to the optical IC wafer 3 is adjusted so that the connection loss between each optical fiber 500 and each optical input / output unit 31 exposed from the opening 110c of the first optical connecting part 110 is minimized. Alternatively, the position of the adapter wafer 11 can be adjusted by connecting a plurality of second optical connecting parts 120 to a plurality of first optical connecting parts 110, respectively.

[0070] In this way, by adjusting the position of the adapter wafer 11 relative to the optical IC wafer 3, it becomes possible to collectively align each of the first optical connecting parts 110 of the adapter wafer 11 with each of the optical IC substrates 30 of the optical IC wafer 3. Then, with each of the first optical connecting parts 110 collectively aligned with each of the optical IC substrates 30, the adapter wafer 11 is bonded to the optical IC wafer 3. For example, the adapter wafer 11 may be bonded to the optical IC wafer 3 with a resin adhesive, or may be bonded to the optical IC wafer 3 by laser welding.

[0071] 8A , optical IC substrates 30 and first optical connecting parts 110 fixed to each other are cut out one by one from the bonded optical IC wafer 3 and adapter wafer 11, and these optical IC substrates 30 and first optical connecting parts 110 are mounted on the substrate of the optical communications module 10. In other words, by cutting the optical IC wafer 3 and the adapter wafer 11 into individual pieces, a plurality of first optical connecting parts 300 with optical IC substrates (first optical connecting parts with circuit boards) are formed. Each first optical connecting part 300 with optical IC substrates has a structure in which one first optical connecting part 110 is bonded to one optical IC substrate 30.

[0072] 8B, a second optical connecting part 120 holding a plurality of optical fibers 500 is connected to the first optical connecting part 110 using a pair of guide pins 150 adhesively fixed to the first optical connecting part 110. This results in the optical connecting assembly 100 shown in Fig. 3. Note that when a glass material is selected for the first optical connecting part 110 as in this embodiment, the glass material has high heat resistance, and therefore the optical IC wafer 3 and the adapter wafer 11 after being aligned together can withstand the reflow process during bonding.

[0073] The effects of the optical connection assembly 100 and the mounting method of this embodiment described above will now be described.

[0074] In this embodiment, the connection end face 120a protruding from the surface 110a of the first optical connecting part 110 is disposed inside an opening 110c formed in the stepped surface 120b of the second optical connecting part 120 and faces the main surface 30a exposed through the opening 110c. The tip of the optical fiber 500 exposed from the connection end face 120a faces the optical input / output unit 31 on the main surface 30a. The distance G1 between the connection end face 120a and the main surface 30a of the optical IC substrate 30 exposed through the opening 110c is 50 μm or less. By reducing the distance G1 in this manner, the connection loss between the optical fiber 500 and the optical input / output unit 31 can be sufficiently reduced even when the optical fiber 500 is directly opposed to the optical input / output unit 31 without a lens. In other words, the optical fiber 500 and the optical input / output unit 31 can be optically connected with low loss using a simple configuration without using a lens.

[0075] Furthermore, if the lens can be omitted in this manner, an increase in connection loss due to a misalignment of the lens can be avoided, even in a high-temperature environment. Furthermore, when the relative positions of the second optical connecting part 120 and the first optical connecting part 110 on the main surface 30a of the optical IC substrate 30 are maintained by the positioning structure M, as in the optical connection assembly 100, it is not necessary to fix the first optical connecting part 110 to the optical IC substrate 30 with an adhesive. Therefore, an increase in connection loss due to peeling of the first optical connecting part 110 from the optical IC substrate 30 can also be avoided. Therefore, the optical connection assembly 100 of this embodiment makes it possible to reduce an increase in connection loss with a simple configuration.

[0076] As in the present embodiment, a gap may be formed between the surface 110a and the step surface 120b. In order to flatten the connection end surface 120a where the optical fiber 500 is exposed, the connection end surface 120a may be polished. In this case, a certain amount of error may occur in the amount of polishing of the connection end surface 120a due to manufacturing. In contrast, in the present embodiment, a gap is formed between the surface 110a and the step surface 120b. In this case, even if an error occurs in the amount of polishing of the connection end surface 120a, the error can be absorbed by the gap. This prevents the surface 110a from hitting the step surface 120b before the connection end surface 120a hits the main surface 30a when connecting the second optical connecting part 120 to the first optical connecting part 110. As a result, the connection end surface 120a can be brought sufficiently close to the main surface 30a, thereby more effectively reducing the increase in connection loss between the optical fiber 500 and the optical input / output unit 31.

[0077] As in this embodiment, the width of the gap from the surface 110a to the step surface 120b, i.e., the distance G2 in the Z-axis direction between the surface 110a and the step surface 120b, may be 20 μm or more and 1 mm or less. When the gap width (distance G) is 20 μm or more, the gap can more reliably absorb errors in the amount of polishing of the connection end surface 120a. Furthermore, when the gap width (distance G2) is 1 mm or less, the insertion length of the guide pin 150 into the guide hole 120d can be prevented from becoming excessively short. This prevents the relative position between the first optical connecting part 110 and the second optical connecting part 120, which is maintained by the insertion of the guide pin 150 into the guide hole 120d, from becoming unstable. Therefore, with the above configuration, the relative position between the first optical connecting part 110 and the second optical connecting part 120 can be more stably maintained while more effectively reducing an increase in connection loss between the optical fiber 500 and the optical input / output unit 31.

[0078] As in the present embodiment, the distance d2 from the step surface 120b to the connection end surface 120a may be longer than the distance d1 from the surface 110a to the main surface 30a. In this case, even if an error occurs in the amount of polishing of the connection end surface 120a, when connecting the second optical connecting part 120 to the first optical connecting part 110, it is possible to prevent the surface 110a from hitting the step surface 120b before the connection end surface 120a hits the main surface 30a. As a result, the connection end surface 120a can be brought sufficiently close to the main surface 30a, so that the increase in connection loss between the optical fiber 500 and the optical input / output unit 31 can be more effectively reduced.

[0079] As in this embodiment, the second optical connecting part 120 has a thickness of 0.5×10 －５ [ / K] or more and 5 × 10 －５ [ / K] or less. In this case, even if a material such as a glass material or a metal material is selected as the material for the first optical connecting part 110, the difference in the linear thermal expansion coefficient of the second optical connecting part 120 relative to the linear thermal expansion coefficient of such a material can be made small. Therefore, it is possible to reduce the occurrence of large positional deviation between the first optical connecting part 110 and the second optical connecting part 120 due to thermal stress caused by the difference in the linear thermal expansion coefficient between the first optical connecting part 110 and the second optical connecting part 120.

[0080] As in the present embodiment, the first optical connecting part 110 may be formed of a glass material. Glass materials have heat resistance and a small linear thermal expansion coefficient, even in high-temperature environments of 85°C or higher, which is difficult for resins commonly used in optical connectors, such as PPS (Poly Phenylene Sulfide) and PEI (Poly Ether Imide). Therefore, glass components are expected to be used in a wider range of applications as components for connecting optical fibers 500 to optical IC boards 30 that are placed near heat-generating semiconductors, such as ASICs (Application Specific Integrated Circuits), which are becoming increasingly practical. Furthermore, because the linear thermal expansion coefficient of glass material is close to that of silicon that constitutes the optical IC board 30, even when the optical connection assembly 100 is used in a high-temperature environment, damage to the first optical connecting part 110 due to thermal stress caused by the difference between the linear thermal expansion coefficient of the first optical connecting part 110 and the linear thermal expansion coefficient of the optical IC board 30 can be reduced. Furthermore, by using a glass material that is transparent to ultraviolet light, the first optical connecting part 110 can be easily fixed onto the main surface 30a of the optical IC substrate 30 with an ultraviolet-curing adhesive.

[0081] As in the present embodiment, the gap between the outer surface of the guide pin 150 and the inner surface of the guide hole 110d may be 2 μm or less, and the guide pin 150 may be formed of a material having a linear thermal expansion coefficient of 10 times or less that of the glass material of the first optical connecting part 110. By providing a gap of 2 μm or less between the inner surface of the guide hole 110d of the first optical connecting part 110 and the outer surface of the guide pin 150, even if the guide pin 150 thermally expands in a high-temperature environment, the thermal expansion of the guide pin 150 can be absorbed by the gap. Therefore, damage to the first optical connecting part 110 caused by the thermally expanded guide pin 150 can be reduced. Furthermore, by using a material of the guide pin 150 having a linear thermal expansion coefficient of 10 times or less that of the glass material, damage to the first optical connecting part 110 due to thermal stress caused by the difference in the linear thermal expansion coefficient between the first optical connecting part 110 and the guide pin 150 can be reduced even when the optical connection assembly 100 is used in a high-temperature environment.

[0082] As in this embodiment, the fiber insertion hole 120c may extend parallel to the guide hole 120d. If the fiber insertion hole 120c extends obliquely relative to the guide hole 120d, there is a possibility that the opening position of the fiber insertion hole 120c and the opening position of the guide hole 120d at the splicing end face 120a may be significantly misaligned, depending on the amount of polishing, when the splicing end face 120a is polished. In contrast, if the fiber insertion hole 120c extends parallel to the guide hole 120d, significant misalignment between the opening positions of the fiber insertion hole 120c and the guide hole 120d due to polishing can be prevented. Therefore, a decrease in the positioning accuracy of the optical fiber 500 caused by misalignment between the opening positions of the fiber insertion hole 120c and the guide hole 120d can be reduced.

[0083] As in the present embodiment, when the linear thermal expansion coefficient of the first optical connecting part 110 is C1 [ / K], the linear thermal expansion coefficient of the second optical connecting part 120 is C2 [ / K], the distance between the centers of the pair of guide holes 120d at room temperature is L1 [mm], and the ambient temperature is T [K], the relationship of the above-mentioned formula (1) may be established. By selecting the material and size of the first optical connecting part 110, the material and size of the second optical connecting part 120, and the temperature range of the ambient temperature so as to satisfy the relationship of formula (1), even when the first optical connecting part 110 and the second optical connecting part 120 thermally expand in a high-temperature environment, it is possible to keep the positional deviation of the optical fiber 500 with respect to the optical input / output unit 31 within an allowable range.

[0084] As in the present embodiment, when the linear thermal expansion coefficient of the first optical connecting part 110 is C1 [ / K], the linear thermal expansion coefficient of the second optical connecting part 120 is C2 [ / K], the distance between the centers of the pair of guide holes 120d at room temperature is L1 [mm], the distance between the centers of the pair of guide holes 110d at room temperature is L2 [mm], and the ambient temperature is T [K], the relationship of the above-mentioned formula (2) may be established. By selecting the material and size of the first optical connecting part 110, the material and size of the second optical connecting part 120, and the temperature range of the ambient temperature so as to satisfy the relationship of formula (2), even when the first optical connecting part 110 and the second optical connecting part 120 thermally expand in a high-temperature environment, it is possible to keep the positional deviation of the optical fiber 500 with respect to the optical input / output unit 31 within an allowable range. Furthermore, in this case, even if a difference in thermal expansion occurs between the first optical connecting part 110 and the second optical connecting part 120, it is possible to reduce damage to one or both of the first optical connecting part 110 and the second optical connecting part 120 due to the difference in thermal expansion.

[0085] As in this embodiment, the mounting method for mounting the first optical connecting component 110 on the main surface 30a of the optical IC substrate 30 includes the steps of preparing an adapter wafer 11 on which a plurality of first optical connecting components 110 arranged two-dimensionally are formed, and an optical IC wafer 3 on which a plurality of optical IC substrates 30 arranged two-dimensionally are formed; positioning the adapter wafer 11 relative to the optical IC wafer 3 so that the plurality of first optical connecting components 110 overlap the plurality of optical IC substrates 30, respectively; bonding the adapter wafer 11 to the optical IC wafer 3 while the adapter wafer 11 is positioned relative to the optical IC wafer 3; and cutting the adapter wafer 11 and the optical IC wafer 3 into individual pieces to form a plurality of first optical connecting components 300 with optical IC substrates.

[0086] The above mounting method differs from the case where the adapter wafer 11 and the optical IC wafer 3 are individually divided and each first optical connecting part 110 is aligned with each optical IC substrate 30 one by one. With the above mounting method, once the adapter wafer 11 is positioned with respect to the optical IC wafer 3, it becomes possible to align each first optical connecting part 110 with each optical IC substrate 30 all at once. In other words, with the above mounting method, once the first optical connecting part 110 with respect to one optical IC substrate 30 is aligned, it is possible to align the first optical connecting parts 110 with all optical IC substrates 30. Therefore, compared to the case where alignment work is performed for each optical IC substrate 30, it is possible to reduce the number of alignment steps to one. Therefore, with the above mounting method, the mounting process of the first optical connecting parts 110 can be simplified.

[0087] The optical connection assembly 100 and the mounting method of the present invention are not limited to the above-described embodiment. The specific aspects of the optical connection assembly 100 and the mounting method of the present invention may be modified without departing from the spirit of the claims.

[0088] 9 differs from the optical connection assembly 100 described above in that it includes a first optical connection part 110A made of a metal material. As the metal material of the first optical connection part 110A, for example, a metal material whose linear thermal expansion coefficient is approximately the same as that of silicon constituting the optical IC substrate 30 is used, taking into consideration that the first optical connection part 110A will be used on the optical IC substrate 30. For example, the metal material of the first optical connection part 110A may be a metal material having a linear thermal expansion coefficient of 1×10 －６ [ / K] or more and 7 x 10 －６ For example, a material having a linear thermal expansion coefficient of 5×10 [ / K] or less is selected as the metal material of the first optical connecting part 110A. －６ Kovar having a linear thermal expansion coefficient of 2×10 [ / K] or less may be selected. －６ Invar having a linear thermal expansion coefficient of 1 / K or less may be selected. Alternatively, a metal ceramic composite material may be selected as the metal material of the first optical connecting part 110A.

[0089] As in the optical connection assembly 100A, by selecting a metal material as the material of the first optical connecting part 110A, it is possible to reduce the occurrence of damage to the first optical connecting part 110A when the guide pin 150 is inserted into the guide hole 120d. －６ [ / K] or more and 7 x 10 －６ Since a linear thermal expansion coefficient of [ / K] or less is close to the linear thermal expansion coefficient of the silicon that constitutes the optical IC substrate 30 on which the first optical connecting part 110A is placed, even when the optical connecting assembly 100A is used in a high temperature environment, it is possible to reduce the occurrence of damage to the first optical connecting part 110A due to thermal stress caused by the difference between the linear thermal expansion coefficient of the first optical connecting part 110A and the linear thermal expansion coefficient of the optical IC substrate 30.

[0090] 10 is different from the optical connection assembly 100 described above in that an anti-reflection film 121 (AR coating) is provided on the connection end surface 120a of the second optical connecting part 120A. As shown in Fig. 10, the anti-reflection film 121 is provided on the connection end surface 120a of the second optical connecting part 120A, for example, and faces the main surface 30a exposed from the opening 110c in the Z-axis direction. The anti-reflection film 121 reduces reflected back light between the optical fiber 500 and the light input / output unit 31.

[0091] As in the above-described embodiment, when the tip of the optical fiber 500 exposed from the connection end face 120a is directly opposed to the optical input / output unit 31 of the optical IC substrate 30 without using other components such as a lens or adhesive, it is difficult to completely abut the tip of the optical fiber 500 against the optical input / output unit 31 due to manufacturing errors or the structure of the optical IC substrate 30. Therefore, a gap may occur between the tip of the optical fiber 500 and the optical input / output unit 31. If such a gap exists, the influence of reflected back light on the optical input / output unit 31 may become a problem. In contrast, in the optical connection assembly 100B, an anti-reflection film 121 is provided on the connection end face 120a, assuming that a gap will be formed between the tip of the optical fiber 500 and the optical input / output unit 31. In this case, the reflected back light between the optical fiber 500 and the optical input / output unit 31 can be effectively reduced, thereby reducing the degradation of optical characteristics caused by the reflected back light.

[0092] <Modification 3> The optical connection assembly 100C shown in FIG. 11A differs from the optical connection assembly 100 described above in that a pair of spacers 122 is provided on the connection end surface 120a of the second optical connecting component 120B. As shown in FIG. 11A , each of the pair of spacers 122 is, for example, a plate-like member whose thickness direction is in the Z-axis direction. The pair of spacers 122 are arranged at a pair of positions on the connection end surface 120a that sandwich the openings of the multiple fiber insertion holes 120c in the Y-axis direction. The pair of spacers 122 are, for example, adhesively fixed to the connection end surface 120a. The pair of spacers 122 may also be adhesively fixed to the main surface 30a exposed through the opening 110c. The pair of spacers 122 are used to maintain the distance G1 between the connection end surface 120a and the main surface 30a exposed through the opening 110c. The thickness of each of the pair of spacers 122 in the Z-axis direction is, for example, 1 μm or more and 20 μm or less.

[0093] 11B , when connecting the second optical connecting part 120B to the first optical connecting part 110, the pair of spacers 122 fixed to the connecting end face 120a are positioned facing the main surface 30a exposed from the opening 110c in the Z-axis direction, and the guide pins 150 are inserted into the guide holes 110d, 120d to bring the second optical connecting part 120B closer to the first optical connecting part 110 until the pair of spacers 122 abut against the main surface 30a in the Z-axis direction. As a result, the pair of spacers 122 are sandwiched between the connecting end face 120a and the main surface 30a in the Z-axis direction. Therefore, the distance G1 between the connecting end face 120a and the main surface 30a is the same as the thickness of each of the pair of spacers 122.

[0094] When a pair of spacers 122 is disposed between the connecting end face 120a and the main surface 30a, as in the optical connection assembly 100C, the distance G1 can be more reliably maintained by abutting the pair of spacers 122 against the connecting end face 120a and the main surface 30a. By setting the thickness of each of the pair of spacers 122 to 20 μm or less, the distance G1 can be further shortened. As a result, the connection loss between each optical fiber 500 exposed from the connecting end face 120a and each optical input / output unit 31 on the main surface 30a can be more effectively reduced.

[0095] Furthermore, when a pair of spacers 122 is provided between the connection end face 120a and the main surface 30a in this manner, a gap can be formed between the optical fiber 500 and the optical input / output unit 31. In this case, unlike when the optical fiber 500 directly abuts against the optical input / output unit 31, foreign matter such as dust that may be present between the optical fiber 500 and the optical input / output unit 31 can be prevented from being crushed by the optical fiber 500 and covering the core of the optical fiber 500. As a result, an increase in connection loss between the optical fiber 500 and the optical input / output unit 31 due to foreign matter can be avoided. Furthermore, when a gap exists between the optical fiber 500 and the optical input / output unit 31, low-loss optical coupling can be achieved without requiring a large pressing force, even when a multi-core fiber is used.

[0096] <Modification 4> The optical connection assembly 100D shown in FIG. 12A differs from the optical connection assembly 100 described above in that a resin coating layer 111 is formed on each of a pair of guide holes 110d of a first optical connecting part 110B. The resin coating layer 111 is a coating layer formed of a resin material. As shown in FIGS. 12A and 12B , the resin coating layer 111 is formed to cover the inner surface of the guide hole 110d. The resin coating layer 111 may be, for example, a cured resin adhesive. A resin material having a higher strength than the glass material of the first optical connecting part 110B is selected as the material for the resin coating layer 111. Examples of such resin coating layer 111 materials include resin materials such as polyphenylene sulfide (PPS), polyetherimide (PEI), and polytetrafluoroethylene (PTFE). These resin materials have excellent mechanical strength, such as durability, wear resistance, and sliding properties, as well as physical strength. Generally, the strength of glass is evaluated by fracture toughness. The fracture toughness can be evaluated by a Vickers strength test and a three-point bending test.

[0097] The resin coating layer 111 covers the entire inner surface of the guide hole 110d, for example, from the front surface 110a to the back surface 110b of the first optical connecting part 110B. The resin coating layer 111 may cover only a portion of the inner surface of the guide hole 110d. The outer diameter D1 of the guide pin 150 is 0.3 mm or more and 0.7 mm or less, and the inner diameter D2 of the guide hole 110d is 0.3 mm or more and 0.7 mm or less, while the thickness T1 of the resin coating layer 111 is, for example, 0.01 mm or more and 0.20 mm or less. In this case, the gap between the resin coating layer 111 and the outer surface of the guide pin 150 is maintained at, for example, 2 μm or less or 1 μm or less.

[0098] When forming the resin coating layer 111 on the inner surface of the guide hole 110d, for example, a resin adhesive is applied to the inner surface of the guide hole 110d, a release agent is applied to the outer surface of the guide pin 150, and then the guide pin 150 is removed from the guide hole 110d. This leaves the cured resin adhesive on the inner surface of the guide hole 110d as the resin coating layer 111. In this way, it is possible to obtain the resin coating layer 111 that covers the inner surface of the guide hole 110d.

[0099] Because the first optical connecting part 110B made of glass is a brittle material, when connecting the second optical connecting part 120 to the first optical connecting part 110B using the guide pin 150, it is expected that defects such as chipping of the first optical connecting part 110B or damage to the first optical connecting part 110B may occur due to excessive force being applied from the second optical connecting part 120 to the first optical connecting part 110B. In contrast, in the optical connection assembly 100D, a resin coating layer 111 that is stronger than glass material is formed on the inner surface of the guide hole 110d of the first optical connecting part 110B. In other words, the resin coating layer 111 protects the parts of the first optical connecting part 110B that are prone to defects.

[0100] Therefore, in the optical connection assembly 100D, it is possible to reduce defects such as chipping of the first optical connecting part 110B and breakage of the first optical connecting part 110B when connecting the second optical connecting part 120 to the first optical connecting part 110B using the guide pin 150. Furthermore, by partially forming the resin coating layer 111 on the glass first optical connecting part 110B, it is possible to utilize the heat resistance of the glass material of the first optical connecting part 110B while reinforcing the parts of the first optical connecting part 110B where defects are likely to occur with the resin coating layer 111.

[0101] <Variation 5> The optical connection assembly 100E shown in FIG. 13A further includes a clip member 130 in addition to the configuration of the optical connection assembly 100 described above. In the optical connection assembly 100E, when the guide pins 150 are inserted into the guide holes 110d and 120d to connect the second optical connecting part 120 to the first optical connecting part 110C, the pair of guide pins 150 adhesively fixed to the first optical connecting part 110C are detachably fitted into the pair of guide holes 120d of the second optical connecting part 120. In this case, there is a possibility that the guide pins 150 may unintentionally come out of the guide holes 120d during use. Therefore, the optical connection assembly 100E includes the clip member 130 as a structure for maintaining the connection between the first optical connecting part 110C and the second optical connecting part 120.

[0102] The clip member 130 includes, for example, a base 131 and a pair of arm portions 132. The base 131 is, for example, a plate-shaped member extending along the Y-axis direction on the second optical connecting part 120. The length of the base 131 in the Y-axis direction is longer than the width of the second optical connecting part 120 in the Y-axis direction. The base 131 is arranged in a position facing the first optical connecting part 110C in the Z-axis direction, with the second optical connecting part 120 sandwiched between them. Specifically, the base 131 is arranged on the second optical connecting part 120 so as to overlap the pair of guide holes 120d of the second optical connecting part 120 in the Z-axis direction.

[0103] The pair of arm portions 132 are plate-like members extending along the Z-axis direction from both ends of the base portion 131 in the Y-axis direction toward the main surface 30a of the optical IC substrate 30. The pair of arm portions 132 extend linearly along the Z-axis direction at positions sandwiching the second optical connecting part 120 and the first optical connecting part 110C, which are connected to each other, in the Y-axis direction. Specifically, the pair of arm portions 132 extend linearly along the Z-axis direction from a position facing the pair of side surfaces 120e of the second optical connecting part 120 in the Y-axis direction to a position facing the pair of side surfaces 110e of the first optical connecting part 110C in the Y-axis direction. The pair of side surfaces 120e are end faces located at both ends of the second optical connecting part 120 in the Y-axis direction. The pair of side surfaces 110e are end faces located at both ends of the first optical connecting part 110C in the Y-axis direction.

[0104] When viewed along the Y-axis direction, each of the pair of arm portions 132 is arranged to overlap the guide hole 120d of the second optical connecting part 120, the guide hole 110d of the first optical connecting part 110C, and the guide pin 150. A hook portion 132a that faces the side surface 110e of the first optical connecting part 110C in the Y-axis direction is formed at the tip of each of the pair of arm portions 132. The hook portion 132a protrudes in the Y-axis direction from the tip of the arm portion 132 toward the side surface 110e. A step portion 110f into which the hook portion 132a fits is formed on the side surface 110e.

[0105] When the hook portion 132a is fitted into the step portion 110f, the hook portion 132a abuts against the step portion 110f in the Z-axis direction. This causes the clip member 130 to engage with the first optical connecting part 110C in the Z-axis direction. In this state, the clip member 130 may press the second optical connecting part 120 toward the first optical connecting part 110C. The clip member 130 is made of a resin material that is elastically deformable in the Y-axis direction when subjected to an external force. Examples of resin materials that can be selected for the clip member 130 include liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyamide (PA46, PA6T, PA9T), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), and polyetherimide (PEI). The clip member 130 is detachably attached to the second optical connecting part 120 and the first optical connecting part 110C in a state in which the guide pins 150 are inserted into the guide holes 110d, 120d and connected to each other. When the clip member 130 is attached to the second optical connecting part 120 and the first optical connecting part 110C, the clip member 130 may press the second optical connecting part 120 toward the first optical connecting part 110C with a pressing force of, for example, 5 N or more and 20 N or less. The clip member 130 may be made of metal, such as sheet metal. The material of the clip member 130 may be, for example, a stainless steel plate, a cold-rolled steel plate, or an aluminum alloy.

[0106] 13B , when attaching the clip member 130 to the second optical connecting part 120 and the first optical connecting part 110C, the pair of arms 132 of the clip member 130 are spread apart in the Y-axis direction, and the second optical connecting part 120 and the first optical connecting part 110C are inserted in the Z-axis direction inside the clip member 130 until the pair of hooks 132a of the pair of arms 132 face the pair of side surfaces 110e of the first optical connecting part 110C in the Y-axis direction. Then, when the pair of arms 132 elastically return to their original positions, the pair of arms 132 fit into the pair of step portions 110f of the first optical connecting part 110C.

[0107] In this state, the pair of hooks 132a abut against the pair of step portions 110f in the Z-axis direction. In this way, the clip member 130 has a snap-fit ​​structure that utilizes the elasticity of the material to fit into the pair of step portions 110f of the first optical connecting part 110C. Note that this structure is not limiting, and a connector structure using an elastic spring may also be adopted. The clip member 130 fitted into the first optical connecting part 110C restricts movement of the second optical connecting part 120 relative to the first optical connecting part 110C. In other words, the connection state between the first optical connecting part 110C and the second optical connecting part 120 is stably maintained.

[0108] When removing the clip member 130 from the first optical connecting part 110C, the pair of arms 132 are pushed apart in the Y-axis direction until the pair of hooks 132a no longer abut against the pair of step portions 110f in the Z-axis direction, and the pair of hooks 132a are separated from the pair of side surfaces 110e of the first optical connecting part 110C. This makes it possible to remove the clip member 130 from the first optical connecting part 110C. In this way, in the optical connecting assembly 100E, the connection state between the first optical connecting part 110C and the second optical connecting part 120 can be stably maintained using the clip member 130. In this way, the optical connecting assembly 100E is provided with a clip member that grips the first optical connecting part 110C in case the guide pin 150 comes out of the guide hole 120d, and therefore, the connection state between the first optical connecting part 110C and the second optical connecting part 120 can be stably maintained.

[0109] The present disclosure is not limited to the above-described embodiments and modifications, and various other modifications are possible. For example, the above-described embodiments and modifications may be combined with each other to the extent that no contradictions exist, depending on the required purpose and effect. Furthermore, the configuration of the optical connection assembly is not limited to the above-described embodiments and modifications. For example, the above-described embodiments and modifications have been described with reference to a case where the connection end face of the second optical connecting part is spaced from the main surface of the circuit board. However, the second optical connecting part may abut the main surface. In this case, the optical waveguide abuts against the optical input / output portion on the main surface. Furthermore, the first reference surface of the first optical connecting part may abut against the second reference surface of the second optical connecting part. In the above-described embodiments and modifications, a protrusion is provided on the first reference surface of the first optical connecting part, and a hole is provided on the second reference surface of the second optical connecting part. However, a hole may be provided on the first reference surface of the first optical connecting part, and a protrusion may be provided on the second reference surface of the second optical connecting part.

[0110] DESCRIPTION OF SYMBOLS 3...Optical IC wafer (second wafer) 3a, 11a...Notch 10...Optical communication module 11...Adapter wafer (first wafer) 20...LSI 30...Optical IC board (circuit board) 30a...Main surface 31...Optical input / output section 40...Electrical wiring 50...Substrate 100, 100A, 100B, 100C, 100D, 100E...Optical connection assembly 110, 110A, 110B, 110C...First optical connecting part 110a...Front surface (first reference surface) 110b...Back surface 110c...Opening 110d, 120d...Guide hole 110e, 120e...Side surface 110f...Step portion 111...Resin coating layer 120, 120A, 120B...Second optical connecting part 120a...Connection end surface 120b...Step surface (second reference surface) 120c...Fiber insertion hole 121...Anti-reflection coating 122...Spacer 130...Clip member 131...Base 132...Arm portion 132a...Hook portion 150...Guide pin 300...First optical connecting part with optical IC board (first optical connecting part with circuit board) 500...Optical fiber (optical waveguide) B...Beam C1, C2...Linear thermal expansion coefficient CL2, CL1, CL3...Central axis D1...Outer diameter D2, D3...Inner diameter d1, d2, G1, G2...Distance L1, L2...Spacing M...Positioning structure T...Environmental temperature

Claims

1. A circuit board including a first optical connecting part mounted on a main surface of a circuit board and including at least one optical input / output part, and a second optical connecting part including at least one optical waveguide and connected to the first optical connecting part, wherein one of the first optical connecting part and the second optical connecting part has a protrusion, and the other of the first optical connecting part and the second optical connecting part has a hole, and the first optical connecting part and the second optical connecting part form a positioning structure that maintains their relative positions by inserting the protrusion into the hole, the first optical connecting part includes: a first reference surface on which the protrusion or the hole is provided, and an opening formed on the first reference surface and exposing the optical input / output part on the main surface from the first reference surface, and the second optical connecting part includes: a second reference surface on which the protrusion or the hole is provided and facing the first reference surface, and a connection end surface that protrudes from the second reference surface, is disposed inside the opening, faces the main surface exposed from the opening, and faces the optical input / output part on the main surface with a tip of the optical waveguide exposed, an optical connection assembly, wherein a distance between the connection end face and the main surface exposed through the opening is 50 μm or less.

2. The optical connection assembly according to claim 1, wherein an air gap is formed between the first reference surface and the second reference surface.

3. The optical connection assembly according to claim 2, wherein the distance between the first reference surface and the second reference surface is 20 μm or more and 1 mm or less.

4. An optical connection assembly according to any one of claims 1 to 3, wherein a distance from the second reference surface to the connection end surface is longer than a distance from the first reference surface to the main surface.

5. The second optical connecting part is 0.5×10 －５ [ / K] or more and 5 x 10 －５ 5. The optical connection assembly according to claim 1, which is formed from a resin material having a linear thermal expansion coefficient of not more than [ / K].

6. An optical connection assembly according to any one of claims 1 to 5, wherein a film is formed on the connection end surface to prevent reflection of light on the connection end surface.

7. An optical connection assembly according to any one of claims 1 to 6, wherein a spacer is disposed between the connection end face and the main surface exposed from the opening, and the thickness of the spacer is 1 μm or more and 20 μm or less.

8. The first optical connection part is 1×10 －６ [ / K] or more and 7 x 10 －６ 8. The optical connection assembly according to claim 1, which is formed from a metal material having a linear thermal expansion coefficient of not more than [ / K].

9. The optical connection assembly according to any one of claims 1 to 7, wherein the first optical connection part is made of a glass material.

10. The optical connection assembly described in claim 9, wherein the protrusion portion is constituted by a guide pin fixed to the first optical connection part while being inserted into a guide hole formed in the first reference surface, the gap between the outer surface of the guide pin and the inner surface of the guide hole is 2 μm or less, and the guide pin is formed of a material having a linear thermal expansion coefficient not more than 10 times the linear thermal expansion coefficient of the glass material of the first optical connection part.

11. The optical connection assembly according to claim 10, wherein the inner surface of the guide hole is provided with a coating layer made of a resin material.

12. An optical connection assembly as described in any one of claims 1 to 11, wherein the hole portion is provided on the second reference plane, the optical waveguide is constituted by an optical fiber held in the second optical connection part, a fiber insertion hole into which the optical fiber is inserted is formed in the connection end face, and the fiber insertion hole extends parallel to the hole portion.

13. An optical connection assembly as described in any one of claims 1 to 12, wherein the positioning structure includes a pair of the protrusions provided on the first reference surface and a pair of the holes provided on the second reference surface, and the relationship of formula (1) is established when the linear thermal expansion coefficient of the first optical connection part is C1 [ / K], the linear thermal expansion coefficient of the second optical connection part is C2 [ / K], the distance between the centers of the pair of the holes at room temperature is L1 [mm], and the ambient temperature is T [K].

14. The optical connection assembly described in any one of claims 1 to 13, wherein the positioning structure includes a pair of the protrusions provided on the first reference surface and a pair of the holes provided on the second reference surface, and the pair of the protrusions are constituted by a pair of guide pins fixed to the first optical connection component in a state where they are inserted into a pair of guide holes formed on the first reference surface, and the relationship of formula (2) is established when the linear thermal expansion coefficient of the first optical connection component is C1 [ / K], the linear thermal expansion coefficient of the second optical connection component is C2 [ / K], the distance between the centers of the pair of the holes at room temperature is L1, the distance between the centers of the pair of the guide holes at room temperature is L2 [mm], and the ambient temperature is T [K].

15. An optical connection assembly as described in any one of claims 1 to 14, further comprising a clip member for gripping the first optical connection part and the second optical connection part, the clip member including: a base portion arranged to sandwich the second optical connection part and face the first reference surface of the first optical connection part; a pair of arm portions extending from the base portion to positions facing a pair of side surfaces of the first optical connection part, respectively; and a pair of hook portions protruding from the pair of arm portions toward the pair of side surfaces, respectively; and the pair of side surfaces are formed with a pair of step portions for engaging with the pair of hook portions, respectively.

16. A mounting method for mounting the first optical connecting component included in the optical connection assembly described in any one of claims 1 to 15 on the main surface of the circuit board, comprising the steps of: preparing a first wafer on which a plurality of the first optical connecting components arranged two-dimensionally are formed, and a second wafer on which a plurality of the circuit boards arranged two-dimensionally are formed; positioning the first wafer with respect to the second wafer so that the plurality of first optical connecting components overlap the plurality of circuit boards, respectively; bonding the first wafer to the second wafer while the first wafer is positioned with respect to the second wafer; and cutting the first wafer and the second wafer into individual pieces to form a plurality of first optical connecting components with circuit boards.

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