Optical circuit mounting substrate, computer, multicore optical ferrule and optical connection method

Abstract

To provide a multicore optical ferrule having connection compatibility with a conventional optical connector and a multicore optical connector.SOLUTION: A multicore optical ferrule 100 comprises: a main body composed of resin compositions; a multicore optical fiber insertion hole 103 provided in the main body for inserting an optical fiber 11; and two guide pin holes 102 provided in the main body for inserting a guide pin. The optical fiber insertion holes are 24 or more, provided on a straight line connecting the two guide pin holes, and include a small diameter part 110 and a large diameter part 106. The small diameter part has an inner diameter of 81 μm. Pitch Pm of the optical fiber insertion hole at a center part is twice as pitch P of the optical fiber insertion hole at parts other than the center part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a manufacturing method of a multi-core optical ferrule for optically connecting optical fibers of an optical cable for transmitting optical signals, an optical circuit mounting substrate including the multi-core optical ferrule, a computer, and an optical connection method.

Background Art

[0002] Optical cables using optical fibers are widely used for information communication in homes and industries because they enable high-speed communication of a large amount of information. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-108867), high accuracy is required for the diameter of the optical fiber hole, the diameter of the guide pin hole, the distance between the centers of the left and right guide pin holes, and the position of each optical fiber hole with respect to the midpoint between the line segments connecting the centers of the left and right guide pin holes. When the ferrule is injection-molded, if the required accuracy for these is not satisfied, it must be discarded as a defective product, resulting in a decrease in the manufacturing yield. However, it does not disclose a solution to the problem that as the number of fiber holes increases, the ferrule warps and eccentricity of the positions of the fiber holes occurs.

[0003] The ferrule for a multi-core optical connector described in Patent Document 1 is a plastic ferrule for a multi-core optical connector of a fitting pin alignment method in which guide pin holes are formed on both the left and right sides of a plurality of horizontally arranged optical fiber holes, and the middle part between the left and right guide pin holes is made thin and vertically symmetric.

[0004] Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-86069) discloses a multi-core optical ferrule, a multi-core optical connector, and an optical module using them, which can utilize a housing for an MT connector and are easy to mold with high precision for 16 cores or more. The multi-core optical ferrule described in Patent Document 2 is a multi-core optical ferrule having a plurality of optical fiber insertion holes and two guide pin holes. The optical fiber insertion holes are provided with 16 or more holes arranged in parallel in a row. The outer shape of the multi-core optical ferrule and the guide pin holes are configured in the same shape and arrangement as the MT ferrule defined in IEC60874-16.

[0005] Patent Document 3 (Japanese Patent Application Laid-Open No. 2007-286354) discloses an optical connector that prevents PC connection inhibition caused by a defective end face angle of the opposing ferrule end face due to a protrusion generated on the obliquely polished surface of the ferrule.

[0006] The optical connector described in Patent Document 3 is an optical connector in which a pair of ferrules having guide pin guide holes drilled in the longitudinal direction of the ferrule and obliquely polished end faces are press-held so that their obliquely polished surfaces are in close contact with each other. A recess is formed at the edge of the guide pin guide hole exposed on the obliquely polished surface.

[0007] Patent Document 4 (Japanese Patent Application Laid-Open No. 2012-194481) discloses an optical connector that can compensate for variations in the fiber protrusion amount between optical fibers and enable low-loss optical connection even if the polishing process at the optical connector end face is omitted.

[0008] The optical connector described in Patent Document 4 includes a fiber holding portion in which a plurality of guide holes for guiding a plurality of optical fibers are formed, a space that connects the plurality of guide holes and accommodates the plurality of optical fibers, and a deformable member that constitutes at least a part of the fiber holding portion and deforms the space to bend a part or all of the plurality of optical fibers within the space.

[0009] Patent Document 5 (Japanese Patent Application Laid-Open No. 5-60949) discloses a multi-core optical connector that can perform line switching from the main line to the standby line (or vice versa) by simply reversing one of a pair of multi-core optical connectors in the connected state, and does not require core wire comparison between the main line side and the standby line side, so that line switching can be performed in an extremely short time.

[0010] In the multi-core optical connector described in Patent Document 5, between two parallel pin holes into which guide pins are inserted, two rows of insertion hole arrays in which optical fiber insertion holes are arranged in the same number and at the same pitch are symmetric with respect to a plane P including the central axis lines of the two pin holes, and are also symmetric with respect to a plane Q perpendicular to the plane P passing through the center of the two pin holes.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0012] In the optical connectors or optical connector ferrules described in Patent Documents 1 to 4 above, techniques for improving dimensional accuracy or characteristics such as mechanical strength are disclosed.

[0013] In particular, Patent Document 2 discloses an optical connector in which light does not conduct between optical fibers even when misconnected to an MT connector. Therefore, the optical connector of Patent Document 2 does not have connection compatibility. In addition, Patent Document 5 discloses a multi-core optical connector in which two rows of insertion hole arrays of optical fiber insertion holes are provided symmetrically with respect to a plane perpendicular to a plane passing through the centers of two pin holes. Since this multi-core optical connector is for switching and connecting one for the main line and the other for the spare line, the connection density is rather low compared to existing connectors, and the pitch in the central part is not twice as large and it does not have connection compatibility. In recent years, there has been a demand for high-density mounting and space saving of ultra-small connectors. Furthermore, compatibility with existing MPO (Multi-Fiber Push On) connectors is also being demanded.

[0014] An object of the present invention is to provide a multi-core optical ferrule and a multi-core optical connector that can achieve low loss and high density even for an optical fiber with a cladding diameter of 80 μm and have connection compatibility with conventional optical connectors. Another object of the present invention is to provide a multi-core optical ferrule and a multi-core optical connector that can enable high-density and high-speed large-capacity communication while having connection compatibility with conventional optical connectors. Still another object of the present invention is to provide a multi-core optical ferrule and a multi-core optical connector that have low connection loss and little variation in quality even for an optical fiber with a cladding diameter of 80 μm.

Means for Solving the Problems

[0015] (1) A multi-core optical ferrule according to one aspect has a main body made of a resin composition, a plurality of optical fiber insertion holes provided in the main body into which optical fibers are inserted, and two guide pin holes provided in the main body into which guide pins are inserted. The optical fiber insertion holes are composed of 24 or more, are arranged on a straight line connecting the two guide pin holes, the optical fiber insertion holes have a small diameter portion and a large diameter portion, the inner diameter of the small diameter portion is 81 μm, and the pitch Pm at the central part of the optical fiber insertion holes is twice the pitch P of the optical fiber insertion holes other than the central part.

[0016] The cladding diameter of the optical fiber currently mainly used is 125 μm, and the outer diameter of the coating for protecting the optical fiber is 250 μm. Then, in order to increase the communication density, as a multi-core optical fiber, a 12-core multi-core optical ferrule that connects 12 optical fibers in a tape shape is currently mainly used. In order to connect this 12-core multi-core optical ferrule, a multi-core optical ferrule with an optical fiber pitch of 250 μm is used as the standard. Furthermore, in order to perform high-density information communication by increasing the number of optical fibers, a 24-core multi-core optical ferrule has been developed in which 12 optical fibers are arranged in two rows and with a pitch of 250 μm. Also, a 16-core multi-core optical ferrule has been developed in which 16 optical fibers are grouped together, the plurality of optical fibers are arranged in a single row, and with a pitch of 250 μm. In recent years, furthermore, for even higher-density mounting, optical fibers with a coating film thickness of 200 μm or 180 μm are also being developed. In this case, a 16-core optical fiber tape with a pitch of 200 μm is also being considered.

[0017] On the other hand, in recent years, there has been a demand for further higher communication density and high-speed large-capacity communication, and it has been considered to further increase the number of cores by setting the cladding diameter of the optical fiber to 80 μm. In particular, this is because not only is the optical fiber used for long-distance communication, but also for optical wiring inside a computer such as a server and mounted on a substrate, it is necessary to perform communication with higher density, higher speed, and larger capacity than before in a narrow environment. However, when arranging 12 bundles of optical fibers with a cladding diameter of 80 μm in two rows for a 24-core connection, due to the structure of the molding die, it becomes difficult to obtain high precision, resulting in a problem of increased connection loss. Also, this leads to a problem that the quality of the product varies greatly as the number of cores of the optical fiber increases. Also, when there is a single row of 12 bundles of optical fibers, since CH1 to CH12 are in a single row, connecting with the one-sided connector reversed enables connection of the same CH. However, when there are two rows of 12 bundles of optical fibers, since CH1 and CH13 are connected, the optical characteristics become unstable.

[0018] Therefore, in the present invention, an optical fiber with an outer diameter of 80 μm is arranged in a single row to improve the positional accuracy of each optical fiber, and the pitch Pm at the center of the optical fiber insertion hole is designed to be twice the pitch P of the optical fiber insertion holes other than the center part, so as to enable low-loss and high-density mounting while having connection compatibility with conventional connectors. It was developed for the purpose of making a multi-core optical ferrule. That is, according to the multi-core optical ferrule of the present invention, by setting the pitch P to 1 / 2 of the conventional standard, the optical fibers with odd numbers starting from the center can communicate as they are in the communication method of the conventional standard, while the optical fibers with even numbers starting from the center located in between can perform high-density communication as newly added optical fibers. In this case, for the newly added optical fibers, they may communicate in the communication method of the conventional standard or in a communication method different from the conventional standard. For example, in the added optical fibers, if communicating in the conventional standard method, the communication density can be doubled, and if communicating by high-frequency / multiplex communication etc. as a new standard, more than twice the amount of information can be communicated. In this way, it is possible to make a multi-core optical ferrule that has connection compatibility with multi-core optical ferrules of existing standards and enables high-speed / high-density mounting between the multi-core optical ferrules of the present invention. Therefore, it also becomes easy to connect an existing optical fiber for long-distance communication and an optical fiber mounted on a substrate.

[0019] In this way, according to the present invention, while using an optical fiber with a cladding diameter of 80 μm, it is possible to make a multi-core optical ferrule that achieves low loss and high density while also having connection compatibility with conventional standards. Furthermore, when there are two rows of 12 bundles of optical fibers, when the connector is reversed and connected, CH1 and CH13 are connected. However, according to the present invention, since all CHs are in a single row, connection with the same CH is possible, and the optical characteristics can be stabilized.

[0020] By setting the inner diameter of the small-diameter portion to 81 μm, a slight clearance of 0.5 μm in radius is created between the optical fiber with a clad diameter of 80 μm, and thus an adhesive can be filled here to securely fix the ferrule while precisely ensuring the positional accuracy of the optical fiber connection end face. That is, when an optical fiber is mounted and fixed to a multi-core optical ferrule, an adhesive is filled on the large-diameter portion side of the optical fiber insertion hole, and the optical fiber is inserted. Then, the adhesive is pushed into the small-diameter portion together with the inserted optical fiber, and the small-diameter portion is filled with the adhesive within a clearance of 0.5 μm in radius. When the adhesive cures and shrinks, the central axis of the small-diameter portion 110 of the optical fiber insertion hole 103 and the central axis of the optical fiber can be precisely aligned.

[0021] (2) The multi-core optical ferrule according to the second invention is the multi-core optical ferrule according to an aspect of the invention, wherein 24 optical fiber insertion holes may be provided and the pitch P may be 125 μm.

[0022] Thereby, high connection compatibility with a general-purpose multi-core optical ferrule can be achieved. That is, the multi-core optical ferrules generally used at present are 12MT ferrules with 12 cores in a row at a pitch of 250 μm and 16MT ferrules with 16 cores in a row at a pitch of 250 μm. Therefore, by setting the pitch P to 125 μm and making a multi-core optical ferrule with 24 cores in a row, high connection compatibility with existing general-purpose multi-core optical ferrules can be achieved. Specifically, when connecting 24 optical fibers, it is preferable that the pitch at the center is 250 μm and the pitch of the optical fiber insertion holes other than the center is 125 μm. In this way, by setting the pitch at the center of the optical fiber insertion holes to 250 μm and the pitch of the optical fiber insertion holes other than the center to 125 μm, the optical fibers with a double interval (12 optical fibers at a pitch of 250 μm) are compatible with the conventional 12-core optical fiber line in terms of both arrangement and communication method, and the 12 optical fibers located therebetween are additional optical fibers, enabling high-density communication. Therefore, it is possible to obtain a multi-core optical ferrule that has connection compatibility with a conventional optical connector and is capable of performing low-loss and high-density mounting communication.

[0023] (3) The multi-core optical ferrule according to the third invention is the multi-core optical ferrule according to an aspect of the invention, wherein 32 optical fiber insertion holes are provided, and the pitch P may be 125 μm.

[0024] Thereby, it is possible to have high connection compatibility with a general-purpose multi-core optical ferrule. That is, the multi-core optical ferrules generally used at present are 12MT ferrules with 12 cores in one row with a pitch of 250 μm and 16MT ferrules with 16 cores in one row with a pitch of 250 μm. Therefore, by making the multi-core optical ferrule with 32 cores in one row with a pitch P of 125 μm, it is possible to have high connection compatibility with existing general-purpose multi-core optical ferrules.

[0025] Specifically, when connecting 32 optical fibers, it is preferable that the pitch at the center is 250 μm and the pitch of the optical fiber insertion holes other than the center is 125 μm. In this way, by making the pitch at the center of the optical fiber insertion holes 250 μm and the pitch of the optical fiber insertion holes other than the center 125 μm, the optical fibers with a double interval (16 optical fibers with a pitch of 250 μm) are compatible with the conventional 16-core optical fiber line in terms of both arrangement and communication method, and 16 optical fibers located therebetween are additional optical fibers, so high-density communication can be performed. Therefore, it is possible to obtain a multi-core optical ferrule that has connection compatibility with a conventional optical connector and is capable of performing low-loss and high-density mounting communication.

[0026] (4) The multi-core optical ferrule according to the fourth invention is the multi-core optical ferrule according to any one of the third inventions from an aspect, wherein the inner diameter of the large-diameter portion is 100 μm, and the distance of the small-diameter portion may be 0.5 mm.

[0027] (5) The multi-core optical ferrule according to the fifth invention, in the multi-core optical ferrule according to the fourth invention in one aspect, the inner diameter of the small-diameter portion has a tolerance of +10% or less on the + side and a tolerance of 5% or less on the - side, the pitch P of the optical fiber insertion holes has a tolerance of ±5% or less, and the bending angle of the optical fiber insertion holes may be 0.5° or less.

[0028] Thus, even an optical fiber with a cladding diameter of 80 μm can be connected with low loss. By setting the inner diameter of the small-diameter portion to have a tolerance of +10% or less on the + side and a tolerance of 5% or less on the - side (i.e., within +10% to -5%), a clearance of 0.5 μm can be ensured within the narrow clearance provided in the small-diameter portion, so that the adhesive can be surely filled. Thereby, the optical fiber can be fixed with high positional accuracy at the connection end face.

[0029] In this case, the tolerance on the + side of the inner diameter of the small-diameter portion is preferably +10% or less, more preferably +8% or less, and even more preferably +5% or less. Also, the tolerance on the - side is preferably -5% or more, more preferably -2% or more, and even more preferably 0% or more.

[0030] The bending angle of the optical fiber insertion hole refers to the angle formed by the perpendicular line of the connection end face and the center line of the optical fiber insertion hole as viewed from a depth position of 0.3 mm or more and 0.5 mm or less from the end face of the multi-core optical ferrule. When the bending angle of the optical fiber insertion hole is 0.5° or less, reliable connection can be achieved when performing multimode optical communication. Also, when the bending angle of the optical fiber insertion hole is 0.3° or less, low-loss connection can be achieved even when performing single-mode optical communication.

[0031] (6) The multi-core optical ferrule according to the sixth invention, in the multi-core optical ferrule according to the fifth invention in one aspect, the main body may be an integrally formed body of a resin composition containing polyphenylene sulfide.

[0032] In this case, since the main body is formed of a resin composition mainly containing polyphenylene sulfide, its dimensions can be maintained with high precision. As a result, displacement of the optical fiber can be suppressed, and adverse effects on connection loss and the like can be reduced. Further, even when the electronic components on the substrate are subject to temperature changes due to operation, characteristics such as connection loss do not fluctuate. Therefore, it is possible to obtain a ferrule for a multi-core optical connector with low connection loss even when an optical wiring is mounted on a substrate. In this specification, the ferrule for a multi-core optical connector may be simply referred to as a ferrule or an MT ferrule.

[0033] (7) In one aspect, the multi-core optical ferrule according to the seventh invention is the multi-core optical ferrule according to the sixth invention, wherein the main body may be provided on a photoelectric conversion element provided on a substrate or installed in an optical transceiver.

[0034] In this case, since the multi-core optical ferrule is installed on the photoelectric conversion element or the optical transceiver on the circuit board, it can be directly connected to the optical fiber. Thereby, optical mounting can be performed at a position closer to the electronic components (such as a CPU) on the circuit board. Also, high-density optical wiring can be mounted even at a position close to the electronic components, and high-speed and large-capacity information processing can be performed. Also, in this case, since the multi-core optical ferrule on the substrate side has connection compatibility, the ferrule on the optical fiber side may be an existing ferrule or the multi-core optical ferrule of the present invention. Thereby, an optical mounting substrate having connection compatibility can be obtained.

[0035] (8) A multi-core optical connector according to another aspect is one in which an optical fiber is connected to the multi-core optical ferrule according to the seventh invention.

[0036] In this case, since it has connection compatibility with an existing optical connector, it is possible to perform optical communication and obtain a multi-core optical connector capable of performing high-density mounting communication. In addition, in an optical connector with a small diameter and high density of optical fibers, if the positional relationship of all the optical fibers deviates slightly from the design, communication failures will occur. In particular, if a plurality of rows of optical fibers are provided, the structure of the mold becomes complicated and it is impossible to obtain the positional accuracy of the optical fibers.

[0037] Therefore, in the multi-core optical connector according to the present invention, the maximum bending angle of the fiber holes can be realized at 0.5 degrees or less. Furthermore, it is preferably 0.3 degrees or less. In addition, in order to achieve miniaturization and further suppress or prevent deviation, it has a plurality of guide pin holes. By realizing miniaturization in this way, high-density, high-speed, and large-capacity optical communication can be directly introduced onto the substrate (or up to the vicinity of the substrate), an optical mounting circuit without electrical wiring can be realized, and compatibility with the current multi-core optical connector can be maintained.

[0038] (9) A method for manufacturing a multi-core optical ferrule according to another aspect is a method for manufacturing a multi-core optical ferrule according to the seventh invention from one aspect. The main body is molded by injecting a resin composition into a cavity formed between an upper mold and a lower mold, and a plurality of optical fiber insertion holes are formed by a plurality of mold pins sandwiched between the upper mold and the lower mold.

[0039] In this case, the errors in the pitch and / or inclination of the plurality of optical fiber insertion holes of the multi-core optical ferrule can be suppressed to the maximum extent. For example, when the plurality of optical fiber insertion holes are formed in two stages, the structure of the mold for forming the insertion holes of the plurality of optical fibers becomes complicated, and it is impossible to stably form the pitch and / or the fiber hole bending angle of the plurality of optical fiber insertion holes. That is, when the plurality of optical fiber insertion holes are arranged in a straight line (single-row arrangement), the plurality of mold pins are firmly sandwiched by a pair of molds (upper mold and lower mold), and the main body is molded by injecting a resin composition into the cavity formed between the pair of molds. At the same time, since the optical fiber insertion holes are formed in the traces where the plurality of mold pins are removed, the error in the fiber hole bending angle can be suppressed to the maximum extent.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0041] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although a plurality of embodiments are shown as embodiments of the present invention, each embodiment may be implemented alone or in combination of one or more embodiments. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0042] [Embodiment] Figs. 1(a), (b), (c), (d) and (e) are examples of diagrams showing the front view, plan view, bottom view, right side view, and left side view of the ferrule 100 of the present embodiment, respectively, and Fig. 2 is the left side view of Fig. 1(e), that is, the enlarged view (tilted counterclockwise by 90°) of the left side view of the present embodiment. Further, Fig. 3 is a cross-sectional view taken along the line A-A' of Fig. 1(b), and Fig. 4 is a schematic diagram for explaining the ferrule 100 of the present embodiment.

[0043] The multi-core optical ferrule 100 (hereinafter, also simply referred to as the ferrule 100) is a main component constituting a multi-core optical connector, and is provided on both the end face of one optical fiber and the end face of the other optical fiber, and precisely adjusts the position of the connection end face of each optical fiber and gives a contact force for optical connection. The ferrule 100 enables simultaneous connection of a plurality of optical fibers, and can be formed by molding a resin composition containing polyphenylene sulfide (hereinafter, referred to as PPS) with a mold. The ferrule 100 has an optical fiber insertion hole 103 for the optical fiber of the optical fiber 11 and a guide pin hole 102 for inserting a guide pin, and is an integral molded product (main body) made of a resin composition containing polyphenylene sulfide.

[0044] (Ferrule 100) As shown in Figs. 1 to 3, the ferrule 100 of the present embodiment is provided with a fiber tape receiving port 101 for the optical fiber tape into which the optical fiber tape is inserted, and a plurality of optical fiber insertion holes 103 for inserting and arranging the optical fiber 11 from which the coating has been removed communicate with the fiber tape receiving port 101. Further, the ferrule 100 is provided with a guide pin hole 102 for positioning and connecting the multi-core optical connector 12 penetrating in parallel with the optical fiber insertion hole 103.

[0045] An opening 104 is formed in the ferrule 100 of the present embodiment as an adhesive filling hole for filling an adhesive. The opening 104 is provided at substantially the center of the upper surface of the ferrule 100 and is for filling an adhesive. The optical fiber tape has its coating at the tip portion removed and is inserted into the fiber tape receiving port 101 from the rear side of the ferrule 100. The plurality of exposed optical fibers 11 are respectively inserted into the optical fiber insertion holes 103 and fixed by an adhesive filled in the opening 104. The connection end face of the optical fiber 11 is fixed by the cured adhesive after inserting the optical fiber 11 into the ferrule 100 and is polished together with the connection surface of the ferrule 100.

[0046] The optical fiber 11 is led out while being protected by a boot made of an elastic material such as rubber or synthetic resin at the leading-out portion of the fiber tape receiving port 101 of the ferrule. The boot is fixed to the boot insertion hole of the fiber tape receiving port 101 of the ferrule 100 with an adhesive. In the ferrule 100 of this embodiment, the optical fiber insertion hole 103, the fiber tape receiving port 101, and the opening 104 communicate with each other. A support portion 105 is provided below the filling portion filled with this adhesive, and a guiding groove for guiding and inducing the optical fiber into the optical fiber insertion hole 103 is formed in this support portion 105. The guiding groove of this embodiment communicates with the rear end of the optical fiber insertion hole 103 and has a shape that is parallel to each other and has a semi-circular cross-section.

[0047] As the optical fiber tape attached to the ferrule 100, an optical fiber tape core wire in which coated optical fiber element wires are integrated with a common coating, or an optical fiber ribbon cord in which a protective coating is further applied on the optical fiber tape core wire can be used.

[0048] (Guide pin hole 102) A guide pin (not shown in the figure) is inserted and fixed in advance into the guide pin hole 102 of one ferrule 100 constituting the multi-core optical connector. By inserting this guide pin into the guide pin hole 102 of the other ferrule 100 and butting the connection surfaces of the multi-core optical connector 12, the connection of the optical fiber 11 is performed. The ferrule 100 configured as described above has the axis of the optical fiber 11 positioned by guide pins, and the connection surfaces are abutted by a coupling clip or the like, enabling optical connection. Therefore, the ferrule 100 is provided with two guide pin holes 102 having a predetermined guide pitch Pg.

[0049] The guide pin diameter is preferably 0.7 mm or 0.55 mm, and the guide pitch is also preferably 4.6 mm or 5.3 mm. Considering that 0.7-mm guide pins are widely used in existing MT ferrules, from the perspective of connection compatibility, the guide pin diameter is preferably 0.7 mm. And the 0.7-mm guide pin has higher reliability and higher alignment accuracy compared to the one with a diameter of 0.55 mm. The inner diameter of the guide pin hole 102 in this embodiment is set to 0.699 mm, and a 0.700-mm guide pin is inserted into the guide pin hole 102. Thereby, connection compatibility with a conventional optical connector can be achieved, and connection reliability can be enhanced.

[0050] Also, the guide pitch Pg of the pair of guide pin holes 102 according to this embodiment is 4.6 mm. Regarding the size of the guide pitch Pg, although it is not particularly limited, from the perspective of connection compatibility, it is preferably the same as the guide pitch Pg widely used in existing MT ferrules.

[0051] As the optical fiber 11, for example, a single-mode or multi-mode one can be used. The optical fiber 11 is standardized by ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) and IEC (International Electrotechnical Commission). In the case of the most commonly used one made of silica glass, the cladding diameters of 125μm ± 1μm and 80μm ± 1μm are defined. Currently, the optical fiber 11 with a cladding diameter of 125μm is mainly used. However, in the future, with the increasing demand for high-density mounting, the operation of the optical fiber 11 with a cladding diameter of 80μm is expected. Therefore, in the present embodiment, the optical fiber 11 with a nominal cladding diameter of 80μm is used. Also, as the optical fiber insertion hole 103 of the ferrule 100, for example, the number of cores can be 16, 24, 32, or 60.

[0052] The MT connector (JIS C5981) of the present embodiment is cabled using a ferrule 100 (JIS C5964-5) and can be coupled by a positioning pin coupling method. Since the ferrule 100 of the present embodiment conforms to the standard of the existing pin coupling method, existing connection components can be utilized for connection, so it has connection compatibility with existing MT ferrules. Also, since it can be connected to an optical transceiver or the like, optical mounting on the substrate 14 can also be realized.

[0053] (Opening 104) A plurality of optical fibers 11 are used as a tape-shaped ribbon, and the outer coating layer of this tape-shaped ribbon is removed to a predetermined terminal length to expose the optical fibers 11, which are inserted into the ferrule 100 and supported at a specified pitch for connection. The ferrule 100 may be a substantially rectangular parallelepiped with a stepped portion on the outside. On one end face side thereof, a fiber tape receiving port 101 for receiving the tape-shaped ribbon into the ferrule 100 is provided, and a support portion 105 for supporting the optical fibers 11 is provided.

[0054] The opening 104 is formed on the upper end surface of the ferrule 100 so as to communicate the internal space with the outside. As shown in FIG. 2, it is opened in a rectangular shape that allows the inside to be seen vertically above the surface where the adhesive is filled. The opening 104 is used not only to visually insert the optical fiber 11 into the support portion 105 but also as a filling port for pouring the adhesive to fix the optical fiber 11. The shape of the filling port (opening) 104 is arbitrary as long as the optical fiber insertion hole 103 can be overlooked.

[0055] (Optical fiber insertion hole 103) The optical fiber insertion hole 103 is a hole that penetrates from the insertion surface to the connection surface of the support portion 105, and adjacent holes are formed in parallel. Also, the axis of the optical fiber insertion hole 103 is provided perpendicular to the connection end surface of the ferrule 100, whereby the connection end surfaces of the optical fibers are precisely abutted on the same axis.

[0056] The angle of the optical fiber insertion hole 103 with respect to the connection end surface is quantified as a bending angle. The bending angle of the optical fiber insertion hole 103 refers to the angle formed by the perpendicular line of the connection end surface and the center line of the optical fiber insertion hole as viewed from a position at a depth of 0.3 mm or more and 0.5 mm or less from the end surface of the ferrule 100. The bending angle of this optical fiber insertion hole is preferably 0.5° or less. Thereby, reliable connection can be achieved when performing multimode optical communication. Also, the bending angle of the optical fiber insertion hole is more preferably 0.3° or less. Thereby, low-loss connection can be achieved even when performing single-mode optical communication. The bending angle in this embodiment is a numerical value measured as follows. That is, the amount of fiber hole misalignment at the end surface of the ferrule 100 is measured with a 2 / 3D automatic dimension measuring machine. For the measurement of the fiber hole misalignment amount, the intersection of the line connecting the midpoints of the two guide holes and its perpendicular bisector is set as the coordinates of (0,0), and then the positions of the respective fiber holes are measured, and the difference between the measured value and the designed value is calculated as the misalignment amount. Furthermore, even at a depth position of 0.3 mm or more and 0.5 mm or less from the end face, the amount of misalignment of the fiber hole position is calculated by the same method as described above. In this way, the fiber hole bending angle is calculated from the difference between the amount of misalignment of the fiber hole position at the end face and the amount of misalignment of the fiber hole position at a predetermined depth position.

[0057] Although the relationship between the connection end face of the ferrule 100 and the optical fiber insertion hole 103 in the present embodiment is as described above, in the field where two ferrules 100 are abutted for optical connection, in order to reduce the reflection attenuation amount, the connection end face of the ferrule 100 may be polished at an oblique angle of 8° and used. In this case, the connection end face will be inclined obliquely, but the two ferrules 100 will be abutted in a straight line by the guide pins, and the optical fibers 11 inside the ferrules 100 will be optically connected in a straight line.

[0058] The optical fiber insertion hole 103 is formed with a large-diameter portion 106 and a small-diameter portion 110 such that the diameter gradually decreases from the base end side through which the optical fiber 11 is inserted toward the tip end side. In the present embodiment, by setting the inner diameter of the small-diameter portion 110 to 81 μm, a clearance of 0.5 μm in radius is generated between the optical fiber with a cladding diameter of 80 μm. Therefore, an adhesive can be filled here to securely fix the optical fiber while precisely ensuring the positional accuracy of the optical fiber connection end face. That is, when the optical fiber is mounted and fixed to the ferrule 100, an adhesive is applied near the guide groove, and the optical fiber is inserted. Then, the adhesive is pushed from the large-diameter portion 106 into the small-diameter portion 110 together with the inserted optical fiber, and the adhesive fills the clearance of 0.5 μm in radius within the small-diameter portion 110. Then, when the adhesive cures, the adhesive shrinks, so that the central axis of the small-diameter portion 110 of the optical fiber insertion hole and the central axis of the optical fiber can be precisely aligned. Note that the inner diameter of the optical fiber insertion hole 103 can be appropriately changed according to the cladding diameter of the inserted optical fiber. For example, when using an optical fiber with a cladding diameter of 50 μm, the inner diameter of the small-diameter portion 110 can be set to 51 μm, and the inner diameter of the large-diameter portion 106 can be set to 80 μm or the like.

[0059] (Board Mounting) FIG. 5 shows an example of a schematic diagram of an optical module mounted on a substrate 14. The ferrule 100 is mounted in a multi-core optical connector 12, and the multi-core optical connector 12 is fixed directly or in the vicinity on the substrate 14 and is connected to the optoelectronic conversion element 13 via the optical fiber 11. There is no particular limitation on the counterpart connected to the ferrule 100 of the present embodiment. For example, it can be connected to an existing MT ferrule 200 or the like, and the optical fiber 11' extending from the MT ferrule 200 is wired to the side of the case 10.

[0060] When optically mounting on the substrate 14 of the electronic circuit, an optical transceiver having an optoelectronic conversion element 13 may be provided at an end of the substrate 14 and connected to the multi-core optical connector 12 (FIG. 5). Examples of the optical transceiver include those in which a light receiving element and a light emitting element as optoelectronic conversion elements are housed in a device holder together with a lens. In this device holder type optical transceiver, the lead (or its FPC) of the optoelectronic conversion element 13 is soldered to the substrate 14 and connected to the ferrule 100 mounted on a receptacle fixed to the substrate 14. In this way, it becomes possible to perform optical wiring board mounting inside a computer such as a server, and it can also be connected to an optical fiber for long-distance communication between computers or the like.

[0061] The connector of the ferrule 100 used as the multi-core optical connector 12 is not particularly limited, and for example, a Lightray MPX connector, an MT-RJ connector, an MPO connector, or the like can be used. The ferrule 100 of this embodiment can be connected as a multi-core optical connector 12 using a general MPO housing (JIS C5982, IEC 61754-7 series), etc. A compression spring may be incorporated inside the housing to mechanically connect the optical fiber 11. This enables easy attachment and detachment with a push-pull operation.

[0062] The main body of the ferrule 100 can be obtained, for example, by transfer molding using a thermosetting resin such as epoxy resin, or injection molding using a thermoplastic resin such as polyphenylene sulfide resin (PPS) or liquid crystal polymer (LCP). The ferrule 100 of this embodiment is formed by molding a resin composition mainly composed of PPS. The resin composition can contain an inorganic filler in addition to PPS. As the inorganic filler, silica particles and fibrous fillers can be contained.

[0063] (Connection Compatibility) FIG. 6 is a schematic diagram for explaining the connection compatibility between the ferrule 100 according to this embodiment and an existing 12-core MT ferrule 90. As for the MT ferrule 90 generally used currently, the 12MT ferrule 90 with 12 cores in a row at a pitch of 250 μm is widely used, and in recent years, a 16MT ferrule with 16 cores in a row at a pitch of 250 μm has also been developed. Therefore, by setting the multi-core optical ferrule 100 with 24 or 32 cores in a row with a pitch P of 125 μm, high connection compatibility with the existing general-purpose MT ferrule 90 can be achieved. As shown in FIG. 6, in the multi-core optical connector 12 according to this embodiment, the pitch Pm of the optical fiber 11 in the central part is 250 μm, and the pitch P of the optical fibers other than the central part is 125 μm. That is, the pitch Pm in the central part is designed to be twice that of the other pitch P. Also, the diameter of the guide pin of the ferrule 100 of this embodiment is φ0.7 mm, and the guide pitch Pg of the pair of guide pin holes 102 is 4.6 mm, which is the same as that of the existing MT ferrule 90.

[0064] By arranging them in this way, the end faces of the odd-numbered optical fibers from the center are optically connected to the fiber end faces of the existing MT ferrule 90, so that communication can be carried out directly using the communication method of the conventional standard. Also, the even-numbered optical fibers from the center become newly added optical fibers that do not exist in the existing MT ferrule 90. Therefore, when the multi-core optical connectors 12 of the present embodiment are connected to each other, high-density optical communication including this newly added optical fiber becomes possible. In this case, for the newly added even-numbered optical fibers, communication may be carried out using the communication method of the conventional standard, or communication may be carried out using a communication method different from the conventional standard. For example, in the added optical fibers, the communication density can be doubled when communicating using the method of the conventional standard, and more than twice the amount of information can be communicated when communicating using high-frequency / multiplex communication or the like as a new standard. Therefore, according to the ferrule 100 of the present embodiment, high-speed / high-density optical communication can be realized, and it is also compatible and communicable with the existing MT ferrule 90.

[0065] An example of the compatible connection between the ferrule 100 according to the present embodiment and the existing MT ferrule 90 will be described in detail using the enlarged view of FIG. 6. The ferrule 100 of the present embodiment and the existing MT ferrule 90 can be easily positioned by guide pins. In this case, the optical fiber 11b of the ferrule 100 of the present embodiment is connected to the optical fiber 91a of the existing MT ferrule 90, the optical fiber 11d is connected to the optical fiber 91b, and the optical fiber 11f is connected to the optical fiber 91c. Further, the optical fiber 11h of the ferrule 100 of the present embodiment is connected to the optical fiber 91d of the existing MT ferrule 90, the optical fiber 11j is connected to the optical fiber 91e, the optical fiber 11m is connected to the optical fiber 91f, and the optical fiber 11n is connected to the optical fiber 91g. As a result, the existing 12 - core MT ferrule 90 and the ferrule 100 of the present embodiment can be optically connected and communicate with each other. Also, since the ferrule 100 of the present embodiment is symmetric and the optical fibers 11 are arranged, communication can be carried out even when the ferrule 100 is turned upside down. In this way, the compatibility between the existing MT ferrule 90 and the ferrule 100 of the present embodiment can be surely maintained.

[0066] Also, when the ferrule 100 of the present embodiment is connected to the ferrule 100 of the present embodiment, communication can be carried out by the 24 - core optical fibers 11, so that high - capacity communication can be achieved. In particular, the optical fibers 11a, 11c, 11e, 11g, 11i, 11k of the ferrule 100 of the present embodiment are the optical fibers 11 that are only connected to the ferrule 100 of the present embodiment and are not connected to the existing MT ferrule 90. Therefore, the same communication method as that of the existing MT ferrule 90 can be adopted, or a new communication method can be adopted. Therefore, according to the ferrule 100 of the present embodiment, high - speed and high - density optical communication can be realized, and it is also compatible with the existing MT ferrule 90 and they can communicate with each other.

[0067] Also, in recent years, for further high - density mounting, optical fibers with a coating film thickness of 200μm or 180μm are being developed. In this case, a 16 - core optical fiber tape with a pitch of 200μm is also being considered. In this case, the pitch Pm at the central part of the ferrule 100 is 200μm, and the pitch P outside the central part is 100μm. And the inner diameter of the large - diameter part may be 90μm.

[0068] (Manufacturing method) FIG. 7 is a schematic diagram showing the manufacturing method of the ferrule 100 of the present embodiment. This will explain the reason for arranging the optical fibers 11 in a straight line. As shown in FIG. 7, an optical fiber insertion hole 103 is formed from a support portion 105 that supports the optical fiber 11. The optical fiber insertion hole 103 is formed with a large-diameter portion 106 and a small-diameter portion 110 such that the diameter gradually decreases from the base end side through which the optical fiber is inserted toward the tip end side. The guiding groove of the support portion 105 is formed with a curvature having a diameter of 100 μm. The large-diameter portion 106 of the fiber insertion hole 103 is formed with a diameter of φ100 μm, and the small-diameter portion 110 of the fiber insertion hole 103 is formed with a diameter of φ81 μm.

[0069] In this case, since the inner diameter of the large-diameter portion 106 is less than 160 μm, only one optical fiber 11 having a cladding diameter of 80 μm can be inserted into each fiber insertion hole 103, and it is possible to surely avoid the inconvenience that two or more optical fibers 11 enter one fiber insertion hole 103. Moreover, only the inner diameter of the large-diameter portion 106 needs to be defined in this way, and no special configuration is required, so the configuration of the ferrule 100 does not become complicated.

[0070] Further, the guiding grooves of the support portion 105 communicate with the rear end of the large-diameter portion 106, are parallel to each other, and are configured to have a semi-circular cross-section. These plurality of guiding grooves are for guiding the optical fiber 11 inserted from the rear surface side of the ferrule 100 into the fiber insertion hole 103. Since the curvature of the guiding groove in the present embodiment is 100 μm, which is the same as the inner diameter radius of the large-diameter portion 106, the end face of the optical fiber disposed in the guiding groove is smoothly guided into the fiber insertion hole 103 as it is.

[0071] Here, FIG. 8 shows an example of a manufacturing die of an existing MT ferrule. In recent years, in order to increase the communication capacity and communication speed, as a method of increasing the density of optical fibers, a 24-core MT ferrule in which 12 optical fibers are arranged in two rows has been developed. FIG. 8 is an example of a die for manufacturing an existing 24-core MT ferrule. As shown in Fig. 8, the pin mold for forming the fiber insertion holes 103 is held while being precisely positioned by a pin holder as shown in Fig. 8(b). However, when the fiber insertion holes 103 are arranged in two rows, as shown in Fig. 8(b), it is necessary to stack three pin holders to hold the pin mold, so there is a problem that the accuracy is inferior compared to the case of a single row. In the case of an optical fiber with a clad diameter of 125 μm as in the prior art, there was no problem even when using a three-stage pin holder as shown in Fig. 8(b) to arrange the fiber insertion holes 103 in two rows. However, in the case of an optical fiber with a clad diameter of 80 μm, this accuracy problem cannot be ignored. That is, when arranging 12 optical fibers with a clad diameter of 80 μm in two rows, due to the problem of the mold structure, it is difficult to maintain high positional accuracy and angular accuracy of the fiber insertion holes 103 on the ferrule connection end face. When arranging 12 optical fibers in two rows as in the prior art for 24-core connection, a problem occurs that the connection loss increases. Also, this leads to a problem that the quality of the product varies greatly as the number of cores of the optical fiber increases.

[0072] In particular, when there is a single row of 12 optical fibers, since CH1 to CH12 are in a single row, the same CH can be connected by reversing one of the connectors on one side. However, when there are two rows of 12 optical fibers, since CH1 and CH13 are connected, the optical characteristics become unstable. That is, when connecting with the same displacement end face in a single row, in the X-axis direction (optical fiber arrangement direction; horizontal direction) during connector connection, the displacement occurs in the same direction in the two ferrules to be connected, so the displacement of the optical fiber end face can be offset. On the other hand, in the Y-axis direction (vertical direction), the displacement occurs in a direction where the displacements of the two ferrules to be connected are separated from each other, so the relative displacement amount becomes large. Thus, the positional accuracy in the Y-axis direction has a great influence on the connection loss compared to the positional accuracy in the X-axis direction. Therefore, when arranging the optical fiber bundle in two rows, it is necessary to ensure the connectivity between the upper row and the lower row with different displacement characteristics, and a problem occurs that the connection loss increases because the canceling effect that occurs in the case of a single row cannot be obtained.

[0073] Therefore, in the present embodiment, as shown in FIG. 7, since the plurality of optical fiber insertion holes 103 are arranged in a straight line, the pin mold is clamped only by two pin holders, so that the pin mold for creating the optical fiber insertion holes 103 can be held precisely and reliably. As a result, the arrangement of the optical fiber insertion holes 103 and the fiber bending angle can be precisely controlled, and a high-precision ferrule 100 can be formed. For the ferrule 100 of the present embodiment, it is preferable that the inner diameter of the small-diameter portion 110 has a tolerance of within 5% on the + side, more preferably within 3%. Also, it is preferable that the tolerance on the - side is 0%. Further, for the ferrule 100 of the present embodiment, the pitch P of the optical fiber insertion holes 103 preferably has a tolerance of within ±5%, more preferably within ±3%. Moreover, for the ferrule 100 of the present embodiment, the bending angle of the optical fiber insertion holes 103 is preferably 0.5° or less, more preferably 0.3° or less. Thereby, even for an optical fiber with a cladding diameter of 80 μm, low loss and high density are achievable, and a ferrule 100 having connection compatibility with a conventional optical connector can be obtained.

[0074] In the present invention, the optical fiber 11 corresponds to the "optical fiber", the optical fiber insertion hole 103 corresponds to the "optical fiber insertion hole", the guide pin hole 102 corresponds to the "guide pin hole", the multi-core optical ferrule 100 corresponds to the "multi-core optical ferrule", the large-diameter portion 106 corresponds to the "large-diameter portion", the small-diameter portion 110 corresponds to the "small-diameter portion", and the multi-core optical connector 12 corresponds to the "multi-core optical connector".

[0075] A preferred embodiment of the present invention is as described above, but the present invention is not limited thereto. It will be understood that various embodiments without departing from the spirit and scope of the present invention may be made. Further, in the present embodiment, the actions and effects according to the configuration of the present invention are described, but these actions and effects are merely examples and do not limit the present invention.

Explanation of Reference Numerals

[0076] 11 Optical fiber 12 Multicore optical connector 100 Multicore optical ferrule 101 Fiber tape receiving port 102 Guide pin hole 103 Optical fiber insertion hole 104 Opening 105 Support part 106 Large diameter part 110 Small diameter part

Claims

1. An electronic circuit board including a photoelectric conversion element or an optical transceiver, an optical fiber connected to the photoelectric conversion element or the optical transceiver, and a multi-core optical ferrule connected to the optical fiber, The multi-core optical ferrule includes: a plurality of optical fiber insertion holes into which optical fibers are inserted; Two guide pin holes into which guide pins are inserted; the optical fiber insertion hole is disposed on a straight line connecting the two guide pin holes, When optical fibers are inserted into each of the optical fiber insertion holes to form an optical connector, the optical connector can be connected to an optical connector having the same number of optical fibers inserted at the same pitch P, and can also be connected to an optical connector having half the number of optical fibers inserted at twice the pitch Pm. an optical fiber inserted into an odd-numbered optical fiber insertion hole from one guide pin hole side of the multi-core optical ferrule and an optical fiber inserted into an even-numbered optical fiber insertion hole from the one guide pin hole side of the multi-core optical ferrule are connected to the photoelectric conversion element or the optical transceiver of different communication standards.

2. 2. The optical circuit mounting board according to claim 1, wherein the communication speed of the even-numbered optical fibers is faster than the communication speed of the odd-numbered optical fibers.

3. the optical connector is capable of connecting an optical fiber for long distance communication used between computers with an optical fiber for optical wiring used inside the computer; an odd-numbered optical fiber from one guide pin hole side of the multi-core optical ferrule communicates in a communication system used in the long distance communication; 3. The optical circuit mounting board according to claim 1, wherein even-numbered optical fibers from said one guide pin hole side of said multi-core optical ferrule communicate in a communication system used in said optical wiring.

4. 4. The optical circuit mounting board according to claim 1, wherein the optical fiber insertion holes are arranged symmetrically so that a reverse connection is possible.

5. An electronic circuit board including a photoelectric conversion element or an optical transceiver, an optical fiber connected to the photoelectric conversion element or the optical transceiver, and a multi-core optical ferrule connected to the optical fiber, The multi-core optical ferrule includes: a plurality of optical fiber insertion holes into which optical fibers are inserted; Two guide pin holes into which guide pins are inserted; a pitch Pm in the central portion of the optical fiber insertion hole is twice the pitch P of the optical fiber insertion hole other than the central portion, an optical fiber inserted into an odd-numbered optical fiber insertion hole from one guide pin hole side of the multi-core optical ferrule and an optical fiber inserted into an even-numbered optical fiber insertion hole from the one guide pin hole side of the multi-core optical ferrule are connected to the photoelectric conversion element or the optical transceiver of different communication standards.

6. An electronic circuit board including a photoelectric conversion element or an optical transceiver, an optical fiber connected to the photoelectric conversion element or the optical transceiver, and a multi-core optical ferrule connected to the optical fiber, The multi-core optical ferrule includes: a plurality of optical fiber insertion holes into which optical fibers are inserted; Two guide pin holes into which guide pins are inserted; The optical fiber insertion holes are arranged in a row, a pitch Pm in the central portion of the optical fiber insertion hole is twice the pitch P of the optical fiber insertion hole other than the central portion, an optical circuit mounting board, in which optical fibers connected to the photoelectric conversion elements or the optical transceivers of two or more different communication standards are inserted into the optical fiber insertion holes provided in the row;

7. An electronic circuit board including a photoelectric conversion element or an optical transceiver, an optical fiber connected to the photoelectric conversion element or the optical transceiver, and a multi-core optical ferrule connected to the optical fiber, The multi-core optical ferrule includes: a plurality of optical fiber insertion holes into which optical fibers are inserted; Two guide pin holes into which guide pins are inserted; the optical fiber insertion hole is disposed on a straight line connecting the two guide pin holes, an optical circuit mounting board, in which optical fibers connected to the photoelectric conversion elements or the optical transceivers of two or more different communication standards are inserted into the optical fiber insertion holes provided on the straight line;

8. A computer comprising the optical circuit mounting board according to claim 1 .

9. A multi-core optical ferrule connected via an optical fiber to an electronic circuit board having a photoelectric conversion element or an optical transceiver, a plurality of optical fiber insertion holes into which optical fibers are inserted; Two guide pin holes into which guide pins are inserted; the optical fiber insertion hole is disposed on a straight line connecting the two guide pin holes, When optical fibers are inserted into each of the optical fiber insertion holes to form an optical connector, the optical connector can be connected to an optical connector having the same number of optical fibers inserted at the same pitch P, and can also be connected to an optical connector having half the number of optical fibers inserted at twice the pitch Pm. A multi-core optical ferrule in which an optical fiber inserted into an odd-numbered optical fiber insertion hole from one guide pin hole side of the multi-core optical ferrule and an optical fiber inserted into an even-numbered optical fiber insertion hole from the one guide pin hole side are connected to the photoelectric conversion element or the optical transceiver of different communication standards.

10. An optical connection method for connecting an optical fiber connected to a photoelectric conversion element or an optical transceiver of an electronic circuit board to an optical fiber for optical wiring or long-distance communication, comprising the steps of: an optical fiber connected to the photoelectric conversion element or the optical transceiver is connected to a multi-core optical ferrule; The multi-core optical ferrule includes: a plurality of optical fiber insertion holes into which optical fibers are inserted; Two guide pin holes into which guide pins are inserted; The optical fiber insertion holes are arranged in a row, An optical connection method, in which optical fibers connected to the photoelectric conversion elements or the optical transceivers of two or more different communication standards are inserted into the optical fiber insertion holes provided in a row.

Images