Mounting structure, device, and data center

Abstract

A mounting structure according to the present disclosure comprises a parent substrate, a child substrate, an optical connector disposed on an upper surface of the parent substrate, an optical chip disposed on a lower surface of the child substrate, a first electrical connector disposed on the upper surface of the parent substrate, a second electrical connector disposed on the lower surface of the child substrate, and an optical fiber optically connected to the optical connector. The upper surface of the parent substrate and the lower surface of the child substrate are disposed to face each other, the optical connector and the optical chip are optically connected, the first electrical connector and the second electrical connector are electrically connected, and the optical fiber is led out from a gap between the parent substrate and the child substrate.

Description

Implementation Structure, Device, and Data Center

[0001] The present disclosure relates to an implementation structure in which an optical connector and an optical chip are optically connected, a device using the implementation structure, and a data center.

[0002] As the amount of data processed increases, in data processing using only electrical wiring, the data transmission distance and the power consumption associated with data transmission increase. In a configuration using an optical fiber as a transmission medium instead of electrical wiring, a configuration is described in which an optical fiber is used for network connection outside an electronic substrate, and electrical wiring is used to connect a plurality of LSIs on the electronic substrate (Non-Patent Document 1).

[0003] FIG. 10A shows an example of the configuration of a conventional electronic substrate 30. In the electronic substrate 30, an electrical connector 311 is provided on a parent substrate 31, and a child substrate 32 including a GPU 352 and a PKG substrate 351 is mounted.

[0004] FIG. 10B shows an example of a GPU connection topology in a conventional electronic substrate. In this configuration example, four adjacent GPUs are interconnected within a block as one block, and are also connected to adjacent blocks. Further, as a network LSI 314 connected to the outside, it has an LSI having a retimer function for amplifying an electrical signal and optimizing timing.

[0005] ”Open Accelerator Infrastructure (OAI) - OCP Accelerator Module (OAM), Base Specification r2.0 v1.0.”, Open Compute Project, September 1343. Problems to be Solved by the Present Disclosure

[0006] However, conventional electronic circuit boards, due to the use of electrical wiring, have limitations on the distance over which high-speed signals can be transmitted, and were limited to connecting up to eight GPUs on a single motherboard. Furthermore, latency increases due to retimers and protocol conversions during external connections, making it difficult to connect GPUs at high density and perform calculations simultaneously. Thus, the number of connectable GPUs was limited, making it difficult to scale up computing resources.

[0007] Furthermore, because the design of electrical wiring for transmitting high-speed signals is limited, changing the GPU connection topology required modifying the parent board itself.

[0008] As described above, with conventional electronic circuit boards, when connecting LSIs such as GPUs with electrical wiring, the distance of the electrical wiring is limited, and connections can only be made on the same board. This presents problems in that it is not possible to increase the number of connected LSIs or change the connection topology.

[0009] To solve the problems described above, the implementation structure according to this disclosure comprises a parent substrate, a child substrate, an optical connector disposed on the upper surface of the parent substrate, an optical chip disposed on the lower surface of the child substrate, a first electrical connector disposed on the upper surface of the parent substrate, a second electrical connector disposed on the lower surface of the child substrate, and an optical fiber optically connected to the optical connector, wherein the upper surface of the parent substrate and the lower surface of the child substrate are arranged facing each other, the optical connector and the optical chip are optically connected, the first electrical connector and the second electrical connector are electrically connected, and the optical fiber is led out from the gap between the parent substrate and the child substrate. Effects of this Disclosure

[0010] According to this disclosure, it is possible to provide an implementation structure that can be adapted to high-speed transmission and implemented with high precision.

[0011] Figure 1A is a schematic diagram showing the configuration of the mounting structure according to the first embodiment of this disclosure. Figure 1B is a schematic diagram showing the configuration of the mounting structure according to the first embodiment of this disclosure. Figure 1C is a diagram for explaining the manufacturing method of the mounting structure according to the first embodiment of this disclosure. Figure 1D is a diagram for explaining the manufacturing method of the mounting structure according to the first embodiment of this disclosure. Figure 2 is a schematic perspective view from above of the mounting structure according to the second embodiment of this disclosure. Figure 3 is a schematic perspective view from above of the parent substrate in the mounting structure according to the second embodiment of this disclosure. Figure 4A is a perspective view from above of the optical connector in the mounting structure according to the second embodiment of this disclosure. Figure 4B is a perspective view from the side of the optical connector in the mounting structure according to the second embodiment of this disclosure. Figure 5A is a diagram for explaining the manufacturing method of the mounting structure according to the second embodiment of this disclosure. Figure 5B is a diagram for explaining the manufacturing method of the mounting structure according to the second embodiment of this disclosure. Figure 5C is a diagram for explaining the manufacturing method of the mounting structure according to the second embodiment of this disclosure. Figure 5D is a diagram for explaining the manufacturing method of the mounting structure according to the second embodiment of this disclosure. Figure 5E is a diagram illustrating a method for manufacturing a mounting structure according to a second embodiment of the present disclosure. Figure 5F is a diagram illustrating a method for manufacturing a mounting structure according to a second embodiment of the present disclosure. Figure 5G is a diagram illustrating a method for manufacturing a mounting structure according to a second embodiment of the present disclosure. Figure 5H is a diagram illustrating a method for manufacturing a mounting structure according to a second embodiment of the present disclosure. Figure 6A is a perspective view of the mounting structure according to a second embodiment of the present disclosure, viewed from below the sub-substrate. Figure 6B is a perspective view of the mounting structure according to a second embodiment of the present disclosure, viewed from above the sub-substrate. Figure 6C is a diagram illustrating the operation of the mounting structure according to a second embodiment of the present disclosure. Figure 7A is a diagram illustrating a mounting structure according to a second embodiment of the present disclosure. Figure 7B is a diagram illustrating a mounting structure according to a second embodiment of the present disclosure. Figure 7C is a diagram illustrating a mounting structure according to a second embodiment of the present disclosure. Figure 7D is a diagram illustrating a mounting structure according to a second embodiment of the present disclosure. Figure 8A is a side cross-sectional view showing the configuration of the mounting structure according to a second embodiment of the present disclosure.Figure 8B is an enlarged side cross-sectional view showing the configuration of the mounting structure according to the second embodiment of the present disclosure. Figure 9A is a diagram illustrating an example of the mounting structure according to the second embodiment of the present disclosure. Figure 9B is a diagram illustrating an example of the mounting structure according to the second embodiment of the present disclosure. Figure 10A is a diagram illustrating a conventional mounting structure. Figure 10B is a diagram illustrating a conventional mounting structure.

[0012] <First Embodiment> The implementation structure according to the first embodiment of this disclosure will be described with reference to Figures 1A and 1B.

[0013] <Configuration of the mounting structure> Figures 1A and 1B show the form of the mounting structure 10 according to this embodiment before and after mounting.

[0014] The mounting structure 10 comprises a parent board 11, a child board 12, an optical connector 13, and an optical chip 14. For example, the parent board 11 has dimensions of 655 mm x 420 mm, and the child board 12 has dimensions of 170 mm x 102 mm.

[0015] The main board 11 is equipped with an optical connector 13, a first electrical connector 111, electrical wiring 112, and a surface-mount fixing jig 113 on its upper surface. The surface-mount fixing jig 113 holds the optical connector 13 to the main board 11.

[0016] The optical connector 13 comprises an upper part 131, a lower part 132, and an elastic structure 133. The upper part 131 has a first optical input / output section 134 and a protrusion 136 on its upper surface for optical connection with the optical chip 14, and a second optical input / output section 135 on its side for optical connection with the optical fiber 16.

[0017] The elastic structure 133 is connected to the lower surface of the upper part 131 and the upper surface of the lower part 132, and deforms in a direction perpendicular to the upper surface of the main substrate 11.

[0018] In the optical connector 13, light propagates between the first optical input / output section 134 and the second optical input / output section 135 via an optical waveguide structure. For example, the optical waveguide structure may include lenses in the first optical input / output section 134 and the second optical input / output section 135 to concentrate or diffuse the input / output light, and may also include mirrors to bend the optical path of the propagating light between the first optical input / output section 134 and the second optical input / output section 135.

[0019] The optical connector 13 is mounted on the main board 11 with its lower part 132 having contact with the upper surface of the main board 11, and is movable horizontally on the upper surface of the main board 11. The movement of the optical connector 13 on the main board 11 is restricted to a predetermined range by a surface-mount fixing jig 113 (described later). This prevents the optical connector 13 from falling off the main board 11.

[0020] The sub-substrate 12 has an optical chip 14, a second electrical connector 121, and a stiffener 123 on its lower surface, and an LSI 15, such as a GPU (Graphics Processing Unit), on its upper surface. The GPU 15 is mounted on a PKG (Package) substrate (not shown) and connected to the second electrical connector 121 via electrical wiring 122.

[0021] Furthermore, the GPU 15 is connected to the optical chip 14 via electrical wiring 142 that penetrates the sub-board 12.

[0022] In the optical chip 14, an electrical signal is converted into an optical signal and output from the optical input / output unit 141. Alternatively, an optical signal input from the optical input / output unit 141 is converted into an electrical signal.

[0023] In the mounting structure 10, the parts (elements) connected by electrical wiring are fixed by soldering. On the other hand, the optical connector 13 is movable (described later).

[0024] In the mounting structure 10, as shown in Figure 1B, the first electrical connector 111 and the second electrical connector 121 are fitted together.

[0025] <Method for Manufacturing the Mounting Structure> The method for manufacturing the mounting structure 10 according to this embodiment will be described with reference to Figures 1C and 1D.

[0026] First, when the first electrical connector 111 and the second electrical connector 121 are connected, the lower surface of the optical chip 14 and the upper surface of the optical connector 13 face each other and come into close proximity (Figure 1A).

[0027] In the optical connector 13, the upper part 131 is provided with one or more protrusions 136 on its upper surface. The inner side walls of each protrusion 136 are inclined toward the outer side walls of the mating portion as they move from the upper surface toward the outside (upwards in the figure). The pair or more protrusions 136 may be arranged symmetrically with respect to the center of the upper surface.

[0028] Subsequently, after the lower edge of the optical chip 14 contacts the inner slope of the protrusion 136 of the optical connector 13 (Figure 1C), the optical connector 13 moves horizontally by sliding along the slope (Figure 1D), and alignment is performed between the first optical input / output section 134 of the optical connector 13 and the optical input / output section 141 of the optical chip 14.

[0029] As a result, the edge (ridge) of the lower surface of the optical chip 14 is positioned in contact with the inner slope of the convex portion 136. A portion of the edge (ridge) of the lower surface of the optical chip 14 may be positioned in contact with the inner slope of the convex portion 136. In this case, the lower surface of the optical chip 14 and the upper surface of the optical connector 13 may be positioned parallel to each other. In this way, the optical connector 13 can be aligned with respect to the optical chip 14.

[0030] In this configuration, in the direction of the opposing protrusions 136, the length of the lower surface of the optical chip 14 is shorter than the distance between the tips of the opposing protrusions 136 and longer than the distance between their bottom surfaces.

[0031] Alternatively, the lower surface of the optical chip 14 may be positioned on the upper surface of the upper part 131 of the optical connector 13 inside the protrusion 136. In this case, for example, a horizontal gap may occur between the edge (ridge) of the lower surface of the optical chip 14 and the ridge of the bottom surface of the protrusion 136, which may cause alignment errors.

[0032] Due to manufacturing tolerances in the solder connections during the mounting of the mounting structure 10, there is a variation of approximately 50 μm in the distance between the child substrate 12 and the parent substrate 11. As a result, for example, when the optical connector 13 and the optical chip 14 come into contact and alignment is completed, a gap may be created between the first electrical connector 111 and the second electrical connector 121, and the first electrical connector 111 and the second electrical connector 121 may not be fully mated (Figure 1D).

[0033] In this case, after the optical connector 13 and the optical chip 14 have made contact, when the optical chip 14 is further pressed against the optical connector 13, the elastic structure 133 contracts, allowing the first electrical connector 111 and the second electrical connector 121 to fully engage (Figure 1B). In this way, the elastic structure 133 can absorb manufacturing tolerances.

[0034] The optical fiber 16 is connected to the optical input / output section 135 on the side of the optical connector 13. The optical fiber 16 is pulled out from between the parent board 11 and the child board 12 through the notch 124 of the stiffener 123.

[0035] In this configuration, the optical chip 14 is mounted directly beneath the LSI, such as the GPU, on the substrate, and the electrical wiring 142 between the LSI and the optical chip 14 is short. This allows for the transmission of signals to the optical chip 14 with low power consumption while maintaining the transmission quality of high-speed signals, such as 100 Gbps.

[0036] Furthermore, on the mounting board, electrical signals are converted into optical signals by the optical chip 14 and output to the optical fiber 16 for transmission, allowing for transmission over longer distances compared to electrical wiring.

[0037] Furthermore, the optical connector 13 on the mounting board has a protrusion 136 that contacts and guides the end of the optical chip 14, and an elastic structure 133 that can absorb manufacturing tolerances, enabling passive optical connection (alignment) when mounting the optical connector 13 (parent board) and the optical chip 14 (child board 12).

[0038] Furthermore, the heights of the optical connector 13 and optical chip 14 are set to match the thickness (approximately 5 mm) of the stiffener 123 and electrical connector on the mounting board, resulting in a smaller and thinner design. This allows for optical connection without changing the conventional electrical connection process, providing high convenience.

[0039] <Second Embodiment> The implementation structure according to the second embodiment of the present disclosure will be described with reference to FIGS. 2 to 9B.

[0040] <Configuration of the Implementation Structure> As shown in FIG. 2, the implementation structure 20 according to this embodiment includes a parent substrate 21, a child substrate 22, an optical connector 23, and an optical chip 24. The optical connector 23 and the optical chip 24 are mounted below the child substrate 22 and are not visible from the outside. An optical fiber 26 is connected to the optical connector 23 of the implementation structure 20 and is led out from the side of the child substrate 22. A network LSI 214 may also be provided.

[0041] As shown in FIG. 3, the parent substrate 21 includes components of an electrical substrate such as a first electrical connector 211, a fixing jig 213 for surface mounting, and a backplane optical connector 215.

[0042] The child substrate 22 includes a GPU 252 and a PKG substrate 251 on its upper surface, and a second electrical connector 121 and an optical chip 24 (described later) on its lower surface.

[0043] As shown in FIG. 4A, the optical connector 23 includes an upper elastic structure 232 that constitutes the upper surface portion, a main body 231, and a lower elastic structure 233 that constitutes the lower surface portion. The height of the optical connector 23 is about 5 mm. The upper surface portion and the lower surface portion are circular in top view, and the diameter is about 15 mm. The main body 231 has a cylindrical shape, and the diameter is about 7 mm to 8 mm. The optical connector 23 is made of a resin with high transmittance of light in the long wavelength band (for example, 1.3 μm) and capable of molding. For example, resins such as polycarbonate, polymethyl methacrylate resin, cycloolefin copolymer, and polyetherimide may be used.

[0044] In the optical connector 23, the upper surface portion includes a first optical input / output portion 234, an upper elastic structure 232, and a convex portion 235. The first optical input / output portion 234 includes a lens 2341 and a stopper 2342 disposed around the lens 2341.

[0045] One pair or a plurality of convex portions 235 are arranged in the vicinity of the outer periphery on the upper surface of the upper elastic structure 232 of the upper surface portion. The one pair or a plurality of convex portions 235 may be arranged at symmetric positions with respect to the center of the upper surface.

[0046] The convex portion 235 is, for example, frustum-shaped. The convex portion 235 may be frustum-shaped with an elliptical cross-section or frustum-shaped with a polygonal cross-section. Or it may be cross-shaped in a top view. In the case of a shape other than frustum-shaped, a single convex portion may be provided.

[0047] The upper elastic structure 232 is an annular leaf spring having a thickness of about 100 μm. The upper elastic structure 232 is deformed by the force that pushes down the convex portion 235 when the optical chip 24 is pressed against the optical connector 23. At this time, the vicinity of the outer periphery where the convex portion 235 is arranged is deformed, and the position is displaced from the upper surface toward the lower surface. On the other hand, the position near the center where the stopper 2342 is arranged does not change.

[0048] As shown in FIG. 4B, the optical connector 23 includes a second optical input / output portion 236 on the side surface of the main body 231. The second optical input / output portion 236 includes a lens 2361 and a positioning convex portion 2362 for connecting an MT (Mechanically Transferable) connector. As an example, the second optical input / output portion 236 includes eight lenses and corresponds to an eight-core fiber.

[0049] Further, the optical connector 23 has a mirror hole on the lower surface of the main body 231 (not shown). The bottom surface of the mirror hole is inclined. This inclined surface functions as a mirror and reflects the light input from the first optical input / output portion 234 toward the second optical input / output portion 236.

[0050] Also, in the optical connector 23, its lower surface portion includes a lower elastic structure 233. The lower elastic structure 233 has the same configuration as the upper elastic structure 232.

[0051] <Manufacturing method of the mounting structure> The manufacturing method of the mounting structure 20 according to the present embodiment will be described with reference to FIGS. 5A to 5H.

[0052] First, as in the usual process, the LSI, electronic components, electrical connectors 211, and surface-mount fixing jigs 213 for the optical connectors 23 are mounted onto the substrate by solder reflow (Figure 5A). The surface-mount fixing jigs 213 are made of metal.

[0053] Next, the optical connector 23 is inserted into the surface mount fixing jig 213 (Figure 5B).

[0054] Next, the optical fiber 26 is connected to the side of the optical connector 23 (Figure 5C).

[0055] Figures 5D to 5F show a bird's-eye view, a top view, and an IVF-IVF' cross-sectional view of the optical connector 23 positioned on the surface-mount fixing jig 213, respectively. In Figures 5E and 5F, the optical connector 23 is shown by a dotted line.

[0056] The surface mount fixing jig 213 comprises a mating portion 2131 and a movement limiting portion 2132. The mating portion 2131 has a curved shape when viewed from above, and the peripheral edge of the lower surface of the optical connector 23 fits into it. The movement limiting portion 2132 is made of a thin plate member and is arranged to surround the peripheral edge opposite to the peripheral edge that mates into the mating portion 2131. In the horizontal direction of this configuration, there is a predetermined gap (for example, about 0.5 mm) between the peripheral edge of the lower surface of the optical connector 23 and the movement limiting portion 2132. As a result, the lower surface of the optical connector 23 contacts the main substrate 21, the movement limiting portion 2132 prevents it from falling out, and it has an in-plane movement range of about 0.5 mm.

[0057] When the optical connector 23 is mounted, the peripheral edge of the lower surface of the optical connector 23 is inserted into the mating portion 2131 from the movable limiting portion 2132 side and mated into the fixing jig 213 for surface mounting. In the movable limiting portion 2132, the first thin plate member located opposite the mating portion 2131 is thinner than the second thin plate member on the side. For example, the thickness of the first thin plate member is 0.1 μm, and the thickness of the second thin plate member is 0.2 μm. The optical connector 23 can be easily inserted into the mating portion 2131 by inserting it while pressing (pressing) the lower surface of the optical connector 23 into contact with the upper surface of the first thin plate member. In the vertical direction of this configuration, there is a predetermined gap (for example, about 0.5 mm) between the peripheral edge and the curved portion. In this configuration, the peripheral edge of the lower surface of the optical connector 23 is covered by the mating portion 2131.

[0058] In this manner, the optical connector 23 is fitted and mounted onto a surface-mount fixing jig 213 that has been pre-fixed to the substrate by solder reflow. This prevents the optical connector 23, which is made of resin, from deforming due to the heating during the solder reflow process.

[0059] Furthermore, when connecting the optical connector 23, it is possible to prevent the optical connector 23 from coming off the surface-mount fixing jig 213 in the insertion / removal direction of the optical fiber 26 (arrow in Figure 5E).

[0060] For example, even if the optical connector 23 is subjected to force when inserting the optical fiber 26 with an MT connector, the insertion (mounting) direction of the optical connector 23 and the insertion direction of the optical fiber 26 are perpendicular at the mating portion 2131, so the optical connector 23 is prevented from falling off the substrate. Furthermore, even if a force is applied that moves the optical connector 23 due to the tension of the optical fiber 26, the movement of the optical connector 23 can be restricted by the fixing jig 213 for surface mounting.

[0061] As an example of the optical fiber 26, if eight optical fibers are arranged in a line at the tip of the MT connector 261, it is necessary to bend the tape fiber 262 when routing the optical fiber 26 on the substrate. Therefore, as shown in Figure 5D, the shape of the tape fiber 262 may be changed to a rollable ribbon fiber 263 that can be easily bent. In a rollable ribbon fiber, eight 250um diameter fibers can be housed within a circle with a diameter of approximately 1 mm.

[0062] Next, the optical fiber 26 is routed and placed on the main substrate 21 (Figure 5G).

[0063] The main board 21 is equipped with a backplane optical connector 215. Figure 5H shows an enlarged view of the area around the backplane optical connector 215. MT connectors 261 are aligned, gathered, and connected to the backplane optical connector 215. For example, the optical fiber 26 has 64 cores (8 cores x 8 strands). The optical connection can be taken out to the outside via the backplane optical connector 215. The main board 21 may also be equipped with a power connector (not shown) for supplying power, etc., by inserting it into the backplane.

[0064] By configuring the connection of the backplane optical connector 215 to the outside, GPUs on the parent board 21 can be arbitrarily connected to each other, and GPUs on other parent boards 21 can be directly connected.

[0065] Furthermore, the routing of the optical fiber 26 may be ensured by a guide (not shown). Fiber routing guides may be marked on the main substrate 21 with solder resist.

[0066] Figure 6A shows a perspective view of the sub-substrate 22 viewed from below. The sub-substrate 22 includes a second electrical connector 221 and an optical chip 24. It also includes a stiffener 223 having a notch 224. The height of the stiffener 223 is, for example, 5 mm to 8 mm.

[0067] The stiffener 223 is a frame-shaped metal plate. This improves mechanical strength and prevents warping of the substrate and damage from external forces.

[0068] In the optical chip 24, the upper surface on which the electrodes are formed is connected to the lower surface of the sub-substrate 22, facing it.

[0069] Figure 6A shows an inset of the optical chip 24 as seen from below. The optical chip 24 has a recess 243 on its lower surface that engages with the protrusion 235 of the optical connector 23.

[0070] The recesses 243 are formed on the silicon substrate of the optical chip 24 by anisotropic dry etching, with an opening diameter of 1 mm and a depth of approximately 150 μm. The recesses 243 are positioned to align with the position of the protrusions 235 of the optical connector 23. For example, it is desirable that one or more pairs of recesses 243 be arranged symmetrically with respect to the center of the optical chip 24.

[0071] Light is transmitted through the substrate (e.g., silicon) of the optical chip 24 and input / output from the bottom surface of the optical chip 24.

[0072] Figure 6B shows a perspective view of the sub-substrate 22 from above. The sub-substrate 22 is equipped with a GPU 252 and a PKG substrate 251 on its upper surface, similar to the conventional configuration.

[0073] The sub-board 22 is mounted by pressing it against the main board 21 so that the second electrical connector 221 is connected to it.

[0074] The protrusion 235 of the optical connector 23 and the recess 243 of the optical chip 24 in the mounting structure 20 will be explained with reference to Figure 6C.

[0075] The inner wall of the recess 243 is inclined such that the opening is wider than the bottom surface due to the characteristics of dry etching. For example, the inclination angle of the inner wall (the inclination angle with respect to the direction perpendicular to the bottom surface of the recess 243, i.e., the upper surface of the optical connector 23) is 10 degrees or less. The recess 243 is, for example, a frustoconical shape that tapers towards the bottom surface. The recess 243 may also be a frustoconical shape. Alternatively, the recess 243 may have a shape that fits the convex portion 235, and may be cylindrical or a polygonal prism. The diameter of the opening of the recess 243 is 1 mm, and the depth of the recess 243 is 150 μm.

[0076] The protrusion 235 is formed by resin molding and is frustoconical in shape, tapering towards its tip. The inclination angle of the inclined side surface of the protrusion 235 is greater than the inclination angle of the inner wall of the recess 243. For example, the diameter of the base of the protrusion 235 is 1.01 mm, the height of the protrusion 235 is 100 μm, and the inclination angle of the inclined side surface is 45 degrees. The protrusion 235 may also be frustoconical in shape.

[0077] The shape of the opening of the recess 243 of the optical chip 24 is preferably the same as or narrower than the shape of the bottom surface of the protrusion 235 of the optical connector 23. As a result, the edge of the opening of the recess 243 of the optical chip 24 is positioned in contact with the side surface of the protrusion 235 of the optical connector 23. A portion of the edge of the opening of the recess 243 may be positioned in contact with the side surface of the protrusion 235.

[0078] The opening of the recess 243 of the optical chip 24 may be wider than the shape of the bottom surface of the protrusion 235 of the optical connector 23. In this configuration, the tip surface of the protrusion 235 of the optical connector 23 is positioned on the bottom surface of the recess 243 of the optical chip 24. In this case, for example, a horizontal gap may occur between the edge of the opening of the recess 243 and the edge of the bottom surface of the protrusion 235, which may cause alignment errors.

[0079] When the sub-substrate 22 is pressed against the main substrate 21 (shaded arrow in Figure 6C), the upper elastic structure 232 deforms as described above, and the ridge (end) of the opening of the recess 243 of the optical chip 24 slides on the slope of the side wall of the convex portion 235 of the optical connector 23 (white arrow in Figure 6C), causing the optical connector 23 to move horizontally (black arrow in Figure 6C), and aligning the first optical input / output portion 234 of the optical connector 23 with the optical input / output portion of the optical chip 24. In this configuration, the inclination angle of the side surface of the convex portion 235 with respect to the direction perpendicular to the upper surfaces of the optical connector 23 and the optical chip 24 is greater than the inclination angle of the inner wall of the recess 243.

[0080] The deformation of this upper elastic structure 232 stops when the lower surface of the optical chip 24 comes into contact with the stopper 2342 of the optical connector 23.

[0081] Furthermore, after the deformation of the upper elastic structure 232 stops, when the child substrate 22 (optical chip 24) is pressed against the parent substrate 21 (optical connector 23), the lower elastic structure 233 contracts, allowing the first electrical connector 211 and the second electrical connector 221 to be fully mated.

[0082] As shown in Figure 7A, the child board 22 is mounted on the parent board 21. In the figure, the dotted line shows the state of the child board 22 (excluding the stiffener) with the stiffener removed, in order to indicate the position of the stiffener 223 on the child board 22.

[0083] Figure 7B shows an example of a GPU connection topology. In a conventional configuration, four adjacent GPUs are interconnected within a block and connected to adjacent blocks. In addition, for external connectivity, each block is connected to a network LSI with a retimer function that amplifies electrical signals and optimizes timing. In addition to this configuration, the GPUs are connected to a backplane optical connector 215.

[0084] Thus, in addition to conventional electrical connections (solid lines), optical connections (dotted lines) have been added. This allows for arbitrary connections between GPUs, increasing the number of GPUs that can be connected.

[0085] Figures 7C and 7D show enlarged views illustrating the arrangement of the stiffener 223. The first optical fiber 26_1 is aligned from below the sub-substrate (first sub-substrate) 22_1, led out through the notch 224 of the stiffener 223, and introduced below the adjacent sub-substrate (second sub-substrate) 22_2. The first optical fiber 26_1 is aligned with the second optical fiber 26_2, which is led out from below the second sub-substrate 22_2, led out through the notch 224 of the stiffener 223, and routed and arranged on the parent substrate 21.

[0086] As shown in Figure 8A, the sub-board 22 is mounted on the main board 21. The optical chip 24 and optical connector 23 are housed within the height range (5 mm) of the stiffener 223.

[0087] As shown in Figure 8B, the GPU 252 is electrically connected to the PKG substrate 251 via a plurality of Cu pillars. The PKG substrate 251 is electrically connected to the sub-substrate 22 via a plurality of microbumps. The optical chip 24 is electrically connected to the back surface of the sub-substrate 22 via solder balls.

[0088] On the main board 21, as shown in Figure 9A, an optical switch 216 may be placed instead of a backplane optical connector. Figure 9B shows an example of the connection topology for this configuration.

[0089] When flexibly changing the connection topology for multiple (e.g., eight) GPUs arranged on a master board 21, an optical switch 216 may be mounted on the master board 21. In this configuration, the optical switch 216 switches the optical signals, transmits them to the optical chip 24 via the optical connector 23, and the optical chip 24 converts them into electrical signals to switch the electrical signals transmitted to the GPUs. This allows for flexible changes to the connection topology.

[0090] Furthermore, some of the ports of the optical switch 216 may be provided for external connections. The optical switch 216 may be manufactured, for example, by planar lightwave circuit technology.

[0091] According to this embodiment, the same effects as the first embodiment are achieved, and the optical connector can be integrally formed into a small, thin structure by resin molding, allowing the optical chip and optical connector to be housed in the narrow gap between the main board 21 and the child board 22. Furthermore, the mounting structure according to this embodiment can be handled in the same way as conventional mounting structures, allowing the number of GPUs to be scaled up while maintaining convenience.

[0092] In this embodiment, an example is shown in which the optical connector has a protrusion and the optical chip has a recess, but it is not limited to this. The optical connector may have a recess and the optical chip may have a protrusion.

[0093] Furthermore, while an example was shown where the inclination angle of the side surface of the convex portion is greater than the inclination angle of the inner wall of the concave portion with respect to the direction perpendicular to the upper surface of the optical connector and optical chip, this is not the only example. The inclination angle of the inner wall of the concave portion may be greater than the inclination angle of the side surface of the convex portion. In this configuration, the optical connector moves horizontally as the ridge (end) of the tip surface of the convex portion slides on the slope of the inner wall of the concave portion of the optical connector. Thus, the inclination angle of the inner wall of the concave portion and the inclination angle of the side surface of the convex portion may be different. At least one part of the ridge of the tip surface or bottom surface of the other of the convex portion or concave portion may be in contact with the side surface or inner wall of either the convex portion or the concave portion.

[0094] The implementation structure according to the embodiments of this disclosure may be used in communication devices. Alternatively, it may be used in devices such as arithmetic units, computing devices (computers), and signal processing devices. A device equipped with the implementation structure according to this embodiment may be used in a data center. Multiple devices may be connected to form a network.

[0095] In the embodiments of this disclosure, examples of the structure, dimensions, materials, etc. of each component in the mounting structure, its manufacturing method, the device, and the configuration of the data center are shown, but the invention is not limited to these examples. Anything that allows the mounting structure, its manufacturing method, the device, and the data center to function and be effective is acceptable.

[0096] It should be noted that this disclosure is not limited to the embodiments described above, and it is evident that many modifications and combinations are possible within the technical concept of this disclosure by a person with ordinary skill in the art.

[0097] Some or all of the embodiments described above, or examples thereof, may also be described as follows, but are not limited to these.

[0098] (Note 1) A mounting structure comprising a parent board, a child board, an optical connector disposed on the upper surface of the parent board, an optical chip disposed on the lower surface of the child board, a first electrical connector disposed on the upper surface of the parent board, a second electrical connector disposed on the lower surface of the child board, an LSI disposed on the upper surface of the child board, and an optical fiber optically connected to the optical connector, wherein the upper surface of the parent board and the lower surface of the child board are arranged facing each other, the optical connector and the optical chip are optically connected, the first electrical connector and the second electrical connector are electrically connected, and the optical fiber is led out from the gap between the parent board and the child board.

[0099] (Note 2) The mounting structure according to Note 1, comprising either a convex portion or a concave portion disposed on the upper surface of the optical connector, and the other either a convex portion or a concave portion disposed on the lower surface of the optical chip, wherein at least one of the inner wall of the concave portion and the side surface of the convex portion is inclined.

[0100] (Note 3) The mounting structure according to Note 1 or Note 2, further comprising a surface mount fixing jig disposed on the upper surface of the main board, wherein the outer edge of the optical connector is curved, and the surface mount fixing jig comprises a curved mating portion and a movable limiting portion made of a thin plate member, wherein one portion of the outer edge of the optical connector is fitted into the mating portion, and the other portion of the outer edge is surrounded by the movable limiting portion.

[0101] (Appendix 4) The mounting structure according to any one of Appendix 1 to 3, further comprising electrical wiring that penetrates the sub-substrate and connects the optical chip and the LSI.

[0102] (Note 5) The mounting structure according to any one of Notes 1 to 4, further comprising a backplane optical connector disposed on the main substrate, wherein the optical fiber is connected to the backplane optical connector.

[0103] (Note 6) The mounting structure according to any one of Notes 1 to 5, further comprising a plurality of child boards and an optical switch arranged on the parent board, wherein the optical switch switches an optical signal, the optical signal is transmitted to the optical chip via the optical connector, the optical chip converts it into an electrical signal, and the electrical signal switches the connection of the LSI.

[0104] (Appendix 7) An apparatus having the mounting structure described in any of Appendix 1 to 6.

[0105] (Note 8) A data center equipped with the devices described in Note 7.

[0106] (Note 9) The mounting structure according to any one of Notes 1 to 6, comprising a plurality of sub-substrates, wherein an optical fiber leading out from one of the plurality of sub-substrates and an optical fiber leading out from another sub-substrate are aligned and arranged on the main substrate.

[0107] (Note 10) The mounting structure according to any one of Notes 1 to 6 or 9, further comprising a stiffener disposed on the outer edge of the sub-substrate and a notch disposed in the stiffener, wherein the optical fiber is led out through the notch.

[0108] (Note 11) The mounting structure according to any one of Notes 1 to 6, 9, or 10, wherein the first electrical connector and the second electrical connector are mated together.

[0109] (Note 12) A method for manufacturing a mounting structure comprising a parent board, a child board, an optical connector disposed on the upper surface of the parent board, an optical chip disposed on the lower surface of the child board, and the upper surface of the optical connector having either a convex portion or a concave portion disposed on the upper surface of the optical connector, the other of the convex portion or a concave portion disposed on the lower surface of the optical chip, and at least one of the inner wall of the concave portion and the side surface of the convex portion having an inclined surface, wherein the upper surface of the optical connector and the lower surface of the optical chip are disposed opposite each other, the method for manufacturing a mounting structure comprising: displacing the upper surface of the optical connector and the lower surface of the optical chip, pushing the optical chip into the optical connector, sliding the ridge portion of either the tip surface of the convex portion or the opening of the concave portion on the inclined surface, and fitting the convex portion into the concave portion.

[0110] (Note 13) The method for manufacturing the mounting structure according to Note 12, wherein the mounting structure further comprises a first elastic structure disposed on the upper surface of the optical connector, a stopper disposed on the upper surface of the optical connector, a second elastic structure disposed on the lower surface of the optical connector, a first electrical connector disposed on the upper surface of the parent substrate, and a second electrical connector disposed on the lower surface of the child substrate, and further comprising the steps of: pushing the optical chip further into the optical connector, bending the first elastic structure, and bringing the lower surface of the optical chip into contact with the stopper; and pushing the optical chip further into the optical connector, bending the second elastic structure, and engaging the first electrical connector and the second electrical connector.

[0111] This disclosure can be applied to communication devices, computing devices, computers, signal processing devices and systems, networks, and data centers.

[0112] 10. Mounting structure 11. Parent board 111. First electrical connector 12. Child board 121. Second electrical connector 13. Optical connector 14. Optical chip 16. Optical fiber

Claims

1. A mounting structure comprising: a parent board; a child board; an optical connector disposed on the upper surface of the parent board; an optical chip disposed on the lower surface of the child board; a first electrical connector disposed on the upper surface of the parent board; a second electrical connector disposed on the lower surface of the child board; and an optical fiber optically connected to the optical connector, wherein the upper surface of the parent board and the lower surface of the child board are arranged facing each other, the optical connector and the optical chip are optically connected, the first electrical connector and the second electrical connector are electrically connected, and the optical fiber is led out from the gap between the parent board and the child board.

2. The mounting structure according to claim 1, comprising either a convex portion or a concave portion disposed on the upper surface of the optical connector, and the other either a convex portion or a concave portion disposed on the lower surface of the optical chip, wherein at least one of the inner wall of the concave portion and the side surface of the convex portion is inclined.

3. The mounting structure according to claim 1 or claim 2, further comprising a fixing jig for surface mounting disposed on the upper surface of the main board, wherein the outer edge of the optical connector is curved, the fixing jig for surface mounting comprises a curved mating portion and a movable limiting portion made of a thin plate member, one portion of the outer edge of the optical connector is fitted into the mating portion, and the other portion of the outer edge is surrounded by the movable limiting portion.

4. The mounting structure according to claim 1, further comprising an LSI disposed on the upper surface of the sub-substrate, and electrical wiring that penetrates the sub-substrate and connects the optical chip and the LSI.

5. The mounting structure according to claim 1 or claim 2, further comprising a backplane optical connector disposed on the parent substrate, wherein the optical fiber is connected to the backplane optical connector.

6. The mounting structure according to claim 1 or claim 2, further comprising a plurality of sub-sub 7. An apparatus comprising the mounting structure described in claim 1 or claim 2.

8. A data center comprising the apparatus described in claim 7.

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