JP5227704B2 - Optical module - Google Patents

Description

  The present invention relates to an optical fiber, one or more substrates holding at least a part of the optical fiber, and one optically coupled while maintaining a positional relationship in alignment with the end of the optical fiber. The substrate includes the light emitting element and / or the light receiving element, and the substrate includes a circuit electrically connected to the light emitting element and / or the light receiving element to operate the light emitting element and / or the light receiving element. The element relates to an optical module (optical wiring structure) mounted on the same substrate as an end of an optical fiber optically coupled to the element.

  In recent years, optical wiring is being studied for high-speed communication devices such as servers, video information devices such as game machines, and small electronic devices such as mobile phones. Conventionally, in these devices, high-density mounting of electric boards and integration of wiring have been advanced. For this reason, even when optical wiring is introduced into these devices, there is a strong demand for space saving and thinning. For this purpose, it is necessary to reduce the thickness of the optical transmission / reception unit and to maintain the wiring shape of the optical fiber.

In Patent Document 1, an electrical / optical conversion device is provided on the transmission side, an optical / electrical conversion device is provided on the reception side, and an optical signal is transmitted by a core and a clad. A metal-coated optical fiber that includes an electric signal receiving device and transmits an electric signal through a metal-coated portion is described.
Patent Document 2 describes an optical fiber coil sensor using one or a plurality of optical fiber coils made of an optical fiber having a resin coating and / or an optical fiber having a metal coating. In Example 8 of Patent Document 2 (the 94th to 101st paragraphs of the specification), a first metal coating having a thickness of 5 to 15 μm and a second metal coating having a thickness of 5 to 50 μm are formed on the resin coating. An optical fiber is described that is durable due to the thick metal coating.
JP-A 62-108412 JP 2005-208025 A

Conventionally, in order to provide an optical wiring on a substrate, there is a problem that it is difficult to maintain the shape of the optical fiber serving as an optical transmission line. The reason is that unlike an electric wire, an optical fiber is less likely to be plastically deformed, and even if the optical fiber is bent by hand or wired straight, it is more stable due to the repulsive force (elastic force) of the optical fiber itself. This is to return to
In a normal case, the optical fiber is stored in a state of being looped in an arc shape (in a state of being wound with a predetermined bending radius) in order to emphasize the storage property. For this reason, when it is desired to bend the optical fiber at a predetermined portion (for example, a corner portion) and straighten the other portion, it is necessary to bend the optical fiber according to the wiring shape or to straighten it.
Further, even if the optical fiber is wired in accordance with a predetermined wiring shape, there is a problem that the optical fiber rises in an unintended place with time and becomes an obstacle in using the device.

  However, in the case of the technique described in Patent Document 1, the effect of the metal coating is only telecommunications, and it is not described that the thickness is necessary for maintaining the wiring shape of the optical fiber. Also, as described in Patent Document 2, when a thick metal coating is simply provided to make the optical fiber strong, it is suitable for maintaining the wiring shape when the optical fiber is wired on the substrate. However, in a portion related to a movable part such as a hinge or a slide portion, deformation such as twisting or bending is repeatedly given to the portion. Then, there is a possibility that the deformation of the optical fiber locally exceeds the yield point and the allowable bending strain. In addition, since the metal coating is thinned to such an extent that the optical fiber can be bent, the metal coating may be damaged by the influence of metal fatigue. The damage of the metal coating not only prevents the metal coating from fully maintaining the wiring shape of the optical fiber, but also may cause the optical fiber to break due to breakage of the metal coating when the operation is frequent.

  The present invention has been made in view of the above circumstances, and in an optical module having a wiring structure in which an optical fiber is wired on a substrate, the wiring shape of the optical fiber on the substrate can be maintained, It is an object to provide an optical module capable of improving the degree of freedom of bending.

  In order to solve the above-described problems, the present invention provides an optical fiber, one or more substrates that hold at least a part of the optical fiber, and an optical fiber that maintains the positional relationship in which the end of the optical fiber is aligned. One or more light emitting elements and / or light receiving elements coupled to each other, the substrate having a circuit electrically connected to the light emitting elements and / or light receiving elements for operating the light emitting elements and / or light receiving elements; and The light emitting element and / or the light receiving element is an optical module mounted on the same substrate as an end of an optical fiber optically coupled to the element, and the optical fiber is a clad of a silica-based optical fiber This is a metal-coated optical fiber in which a resin coating is provided on the outer periphery of the optical fiber, and a metal coating is provided on the outer periphery of the resin coating to maintain the wiring shape of the optical fiber. An optical fiber having a void portion which is a portion not having a metal coating in a middle portion in the longitudinal direction of the fiber and having a resin coating exposed in the void portion is wired in a bent state. An optical module is provided.

It is preferable that one end of the optical fiber is optically coupled to the light emitting element, and the other end of the optical fiber is optically coupled to the light receiving element.
The length of the gap is preferably in the range of 30 mm or more and 50 mm or less.
The gap is preferably provided at two or more locations for one metal-coated optical fiber.
The core diameter of the optical fiber is in the range of 50 μm or more and 62.5 μm or less, and the metal coating is provided on the outer periphery of the first metal coating and the first metal coating provided on the outer periphery of the resin coating. Preferably, the second metal coating is formed.
The thickness of the first metal coating is preferably in the range of 0.1 μm or more and 5 μm or less.
The thickness of the second metal coating is preferably in the range of 50 μm or more and 95 μm or less.
The first metal coating is preferably made of any one of Cu, Ni, Sn, Cr, Zn, a Cu—Zn alloy, or a Cu—Ni alloy.
The second metal coating is preferably made of any one of Cu, Ni, Cr, Zn, Ag, Au, a Cu—Zn alloy, or a Cu—Ni alloy.
The metal-coated optical fiber is preferably soldered on a land pattern on the substrate and wired substantially parallel to the substrate.
Two or more substrates are provided, and the metal-coated optical fiber has the gap at a position where the optical fiber is wired between the substrates, and the relative position between the substrates can change between the substrates. It preferably has a structure.
Moreover, this invention provides the apparatus characterized by having the optical module which concerns on this invention mentioned above.

According to the present invention, by using a metal-coated optical fiber having a void portion (a portion having no metal coating in the middle portion), the wiring shape of the optical fiber can be maintained by the metal coating, and the void portion By bending and laying the optical fiber, the degree of freedom in bending can be improved, and failures due to the optical fiber floating in an unintended place with time can be prevented and reliability can be improved. Further, since the place having the metal coating is easily plastically deformed, it becomes easy to straighten the bending of the optical fiber, and the mounting workability can be improved.
Further, by soldering the metal-coated optical fiber onto the land pattern of the substrate, the metal-coated optical fiber can be wired substantially parallel to the substrate at a position close to the substrate.

  The optical module has two or more substrates, and the metal-coated optical fiber has a gap where the optical fiber is routed between the substrates, and the relative position between the substrates can change between the substrates. When it has, even if board | substrates are movable by hinges, a slide part, etc., damage to a metal coating | cover and an optical fiber can be suppressed.

The present invention will be described below with reference to the drawings based on the best mode.
In the present invention, an optical module refers to an optical fiber, one or more substrates that hold at least a part of the optical fiber (which may be the entire length or the majority of the optical fiber), and an end of the optical fiber. One or more light-emitting elements and / or light-receiving elements optically coupled to each other while maintaining an aligned positional relationship, and the substrate includes the light-emitting elements and / or light-receiving elements (hereinafter referred to as light-emitting elements and light-receiving elements). The light receiving element is generically referred to as “light emitting / receiving element” in some cases.), And the light emitting element and / or the light receiving element are optically connected to the element. This is an optical wiring structure having a configuration mounted on the same substrate as the ends of optically coupled optical fibers.
The optical module of the present invention may be one in which two or more optical fibers are wired on a substrate.

In the optical module, it is preferable that one end of the optical fiber is optically coupled to the light emitting element and the other end of the optical fiber is optically coupled to the light receiving element. As described above, a configuration in which transmission and reception are paired is suitable for information transmission by light.
A structure in which a light emitting element or a light receiving element is only coupled to one end of the optical fiber may be used. In that case, in order to transmit information by light, the other end of the optical fiber has a structure such as a ferrule or a connector, and the connection destination needs to be attached with a separate light receiving module or light transmitting module configured to receive the ferrule or the like. There is. For example, when a transmitter is attached to one end of an optical fiber of an optical module and a ferrule is attached to the other end, the ferrule on the other end is connected to a receptacle-type receiver to transmit and receive Can do.

An example of the configuration of the optical module of the present invention is shown in FIG. The optical module 20 shown in FIG. 1 is optically maintained while maintaining the positional relationship in which the optical fiber 10, one substrate 1 that holds the entire length of the optical fiber 10, and the end 7 of the optical fiber 10 are aligned. And a light-receiving element (not shown) optically coupled with the transmitter 2 incorporating a light-emitting element (not shown) coupled to the optical fiber 10 while maintaining an aligned positional relationship with respect to the end 8 of the optical fiber 10. ), And the transmitter 2 and the receiver 3 are mounted on one substrate 1.
In the present invention, “the light receiving and emitting element is mounted on the substrate” is not limited to the case where the bare light emitting and receiving element is mounted on the substrate. "Receiver is implemented".

The substrate 1 includes a circuit (not shown) that is electrically connected to the light emitting / receiving element. Examples of such a substrate include a printed circuit board in which a circuit is formed by etching a copper foil, printing a conductive paste, or the like.
According to the optical module 20, since the end portions 7 and 8 of the optical fiber 10 and the transmitter 2 and the receiver 3 are mounted on one substrate 1, light receiving and emitting elements for the end portions 7 and 8 of the optical fiber 10. Alignment becomes easier.

As shown in FIG. 2, the optical fiber 10 used in the optical module 20 according to the first embodiment of the present invention has a metal coating 18 for maintaining the shape of the optical fiber on the outer periphery of the optical fiber 15. The metal-coated optical fiber 10 is provided.
Depending on the material and thickness of the metal layer, the metal coating 18 is provided with a “koshi” (elastic limit stress exceeding the repulsive force of the optical fiber) that resists the repulsive force (restoring force) of the optical fiber 15. 10 can be held in a straight shape (linear shape). Further, the metal coating 18 can be plastically deformed, and can be deformed in a bent state or a straight state with a high degree of freedom.
Further, in the optical module 20 of this embodiment, the metal-coated optical fiber 10 is attached to the substrate 1 by attaching the solder 4 between the land pattern 6 on the substrate 1 and the metal coating 18 of the metal-coated optical fiber 10. It is fixed. By soldering the metal-coated optical fiber 10 onto the land pattern 6 of the substrate 1, the metal-coated optical fiber 10 can be wired substantially parallel to the substrate 1 at a position close to the substrate 1.

FIG. 7 shows details of the cross-sectional structure of the metal-coated optical fiber 10.
The optical fiber 15 includes an optical fiber bare wire 13 made of a core 11 at the center and a clad provided on the outer periphery thereof, and a resin coating 14 on the outer circumference of the clad 12 of the optical fiber bare wire 13.
The metal coating 18 includes a first metal coating 16 provided on the outer periphery of the resin coating 14 and a second metal coating 17 provided on the outer periphery of the first metal coating 16.
The detailed structure shown in FIG. 7 is one example suitable for the present invention, but the metal-coated optical fiber applied to the optical module of the present invention is not intended to be limited to this structure.

  For the bare optical fiber 13, it is preferable to use a silica-based optical fiber in which the core 11 and the clad 12 are made of silica-based glass. A silica-based single-mode optical fiber can be adopted as the silica-based optical fiber, but it is preferable to use a silica-based multimode optical fiber as the optical fiber in the apparatus. The diameter of the core 11 can be in the range of 50 μm or more and 62.5 μm or less, for example.

The first metal coating 16 preferably has a thickness in the range of 0.1 μm to 5 μm. Examples of the metal material constituting the first metal coating 16 include Cu, Ni, Sn, Cr, Zn, a Cu—Zn alloy, and a Cu—Ni alloy.
The second metal coating 17 preferably has a thickness in the range of 50 μm or more and 95 μm or less. Examples of the metal material constituting the second metal coating 17 include Cu, Ni, Cr, Zn, Ag, Au, a Cu—Zn alloy, and a Cu—Ni alloy.

  Further, as shown in FIG. 8, the metal-coated optical fiber 10 has a gap portion 19 that is a portion that does not have the metal coating 18 in the middle portion in the longitudinal direction of the optical fiber. By removing the metal coating 18 in the middle of the metal-coated optical fiber 10 having the metal coating 18 over the entire length until the resin coating 14 is exposed by a cleaver, a laser processing machine, etching, a mechanical stripper, etc. Can be formed. For example, when a chemical solution such as an acid that dissolves the metal constituting the metal coating 18 is used, it is possible to selectively remove only the metal coating 18 without removing the resin coating 14. Alternatively, in the step of attaching the metal coating 18 to the resin coating 14 of the optical fiber 15, if a part or all of the part where the gap 19 is to be provided is masked with an insulator, the part is attached to the part. Since the amount of the metal coating to be performed can be reduced or eliminated, the amount of the metal coating to be removed when forming the gap portion 19 is reduced, which facilitates the metal coating removal operation, which is preferable.

The part having the metal coating 18 can be handled as a rigid part capable of maintaining the wiring shape. Further, the gap portion 19 without the metal coating 18 can be handled as a flexible portion that can be bent freely (within the range of the allowable bending radius of the optical fiber). For this reason, when the optical fiber 10 is wired, the air gap portion 19 is arranged at a bending portion having a small curvature radius in the substrate 1 so that highly reliable optical wiring (especially in-device wiring) can be easily provided. Can do.
The gap portion 19 can be provided at only one place per one metal-coated optical fiber, or can be provided at two or more places.

  An optical fiber 15 (an optical fiber having a resin coating 14) exposed in the gap 19 is wired in a bent state at a position away from the substrate 1. The length of the gap 19 for laying the optical fiber in a bent state on the substrate 1 is about 1.5 times the minimum bending radius or more (for example, when the minimum bending radius is 5 mm, The length is preferably 8 mm or more.

The wiring shape of the metal-coated optical fiber 10 can be arbitrarily set so that a space (area) for mounting the other component 5 on the substrate 1 can be secured. For example, as shown in FIG. 1, it is preferable to wire the metal-coated optical fiber 10 around the periphery of the substrate 1 because a space for mounting the other components 5 can be secured widely in the central portion of the substrate 1. Examples of the other component 5 include various electronic components such as an inductor, a capacitor, a resistor, and a diode.
In particular, as shown in FIG. 1, in the case of a rectangular substrate 1, when the optical fiber 10 is routed so as to pass through the corner portion of the substrate 1, the optical fiber 10 is bent at the corner portion of the substrate 1. When doing so, wiring can be performed with a small radius of curvature.

Further, since the metal coating 18 is exposed on the outer surface of the metal-coated optical fiber 10, solder is provided between the land pattern 6 on the substrate 1 and the metal coating 18 of the metal-coated optical fiber 10 as shown in FIG. By attaching 4, the metal-coated optical fiber 10 can be fixed to the substrate 1. By soldering the metal-coated optical fiber 10 onto the land pattern of the substrate, the metal-coated optical fiber can be wired substantially parallel to the substrate at a position close to the substrate.
Since the metal coating 18 has shape retention characteristics, the metal coated optical fiber 10 is not deformed by its own weight, and the metal coating 18 can be prevented from contacting the substrate 1. In addition, it is possible to prevent the metal-coated optical fiber 10 from greatly deviating from or jumping up from a desired wiring position, and to realize space saving and low profile. Further, since the optical transmission line is not affected by electrical noise, high-density mounting on the substrate can be achieved.

  It is also possible to solder the metal coating 18 of the metal-coated optical fiber 10 to the housing after the substrate is attached to the device housing. When the optical fiber is fixed by such soldering, the metal coating 18 is electrically divided by the gap portion 19, so that the potential of the soldered portion is the potential of the housing (module case) (usually GND). The degree of freedom in designing the land pattern (solder pad) 6 for soldering the metal-coated optical fiber 10 on the substrate 1 is improved.

  Also, as shown in FIG. 9, the metal coating 18 of the metal-coated optical fiber 10 is connected to the circuit on the substrate 1 by connecting the metal coatings 18 that are electrically separated through the gap portion 19 to each other. It can also be used for transmission. The wiring between the metal coatings 18 may be simply a jumper wire for conducting, but further, when connected via electronic components such as an inductor L, a capacitor, a resistor R, a diode, etc. The metal coating 18 as a transmission line is used as an electrical wiring having functionality such as reducing the influence of noise received from nearby electronic components and electrical wiring, and adjusting applied voltage and current value. Can do.

In another embodiment of the present invention, the metal-coated optical fiber is wired so as to span a plurality of substrates, at least a part of the length of the optical fiber is held on the substrate, and the optical fiber is stretched between the substrates. A gap portion is provided at the lined portion, and the relative position between the substrates can change between the substrates. In this case, it is suitable as an optical wiring at a location where a plurality of casings of the device are relatively movably connected by a hinge portion or a slide portion, such as flip and slide of a mobile phone.
In addition, the optical module can be folded and stored in the space between the substrates before being attached to the housing, which is excellent from the viewpoint of storage performance and mounting workability.

  The example shown in FIGS. 3 and 4 is suitable when a plurality of substrates are relatively rotated and moved by a hinge portion or the like. In that case, it is preferable that the length of the space | gap part arrange | positioned between board | substrates exists in the range of 30-50 mm.

  The optical module 30 of the second embodiment shown in FIG. 3 includes an optical fiber 10, two substrates 31 and 32 that hold most of the length of the optical fiber 10, and the optical fiber 10 on the first substrate 31. A transmitter 2 containing a light-emitting element (not shown) optically coupled while maintaining an aligned positional relationship with respect to the end 7 of the optical fiber 10, and the end of the optical fiber 10 on the second substrate 32. 8 includes a receiver 3 including a light receiving element (not shown) optically coupled while maintaining a positional relationship in which alignment is performed with respect to 8. The transmitter 2 is mounted on the first substrate 31, and the receiver 3 is mounted on the second substrate 32.

  In the optical module 30 of the second embodiment, the two substrates 31 and 32 are relatively rotatable as indicated by an arrow 33, and the optical fiber 10 is arranged at a position where the optical fiber 10 is straddled between the substrates 31 and 32. A gap portion 19 is provided, and the optical fiber 15 (an optical fiber having the resin coating 14) exposed in the gap portion 19 is wired in a state where it can be bent in a space 34 between the substrates 31 and 32. .

  The optical module 30 of the second embodiment including the two substrates 31 and 32 is a first substrate of the optical module 30 in, for example, a device in which a first housing and a second housing are connected via a hinge. 31 can be used when the first substrate 31 is installed in the first housing, the second substrate 32 is installed in the second housing, and the space 34 between the substrates 31 and 32 is disposed at the bent position by the hinge portion. The rotation direction by the arrow 33 is such that the rotation center axis 35 is along the sides 36 and 37 of the substrates 31 and 32 facing each other.

  The optical module 40 of the third embodiment shown in FIG. 4 includes an optical fiber 10, three substrates 41, 42, 43 that hold most of the length of the optical fiber 10, and light on the first substrate 41. A transmitter 2 including a light-emitting element (not shown) optically coupled while maintaining an aligned positional relationship with respect to the end portion 7 of the fiber 10, and the optical fiber 10 on the third substrate 43. The receiver 3 includes a light receiving element (not shown) optically coupled to the end portion 8 while maintaining an aligned positional relationship. The transmitter 2 is mounted on the first substrate 41, and the receiver 3 is mounted on the third substrate 43. Neither the light receiving element nor the light emitting element is mounted on the second substrate 42.

  In the optical module 40 according to the third embodiment, the three substrates 41, 42, and 43 can be relatively rotated, and the space 44 between the first substrate 41 and the second substrate 42 and the second substrate 42. In this example, the gap portion 19 is provided in accordance with the space 45 between the first substrate 43 and the third substrate 43. The configuration around the inter-substrate spaces 44 and 45 can be the same as the configuration around the inter-substrate space 34 in the optical module 30 of the second embodiment.

  The examples shown in FIGS. 5 and 6 are suitable when a plurality of substrates are relatively translated by a slide portion or the like. Generally, the stroke (movement distance) of a slide portion used in an electronic device or the like is about 50 mm at the maximum (commercially available mobile phones are about 30 to 40 mm). The length of the gap portion 19 is preferably within a range of 45 to 65 mm. When the distance between the substrates and the stroke of the slide movement are longer, it is preferable to make the length of the gap portion 19 between the substrates longer in the metal-coated optical fiber.

The optical module 50 according to the fourth embodiment shown in FIG. 5 includes an optical fiber 10, two substrates 51 and 52 that hold the optical fiber 10, and the end 7 of the optical fiber 10 on the first substrate 51. The transmitter 2 incorporating a light emitting element (not shown) optically coupled while maintaining the aligned positional relationship is aligned with the end 8 of the optical fiber 10 on the second substrate 52. And a receiver 3 including a light receiving element (not shown) optically coupled while maintaining the positional relationship. The transmitter 2 is mounted on the first substrate 51, and the receiver 3 is mounted on the second substrate 52.
The two substrates 51 and 52 can relatively reciprocate as indicated by an arrow 53, and a gap portion 19 is provided at a location where the optical fiber 10 is wired between the substrates 51 and 52. The optical fiber strand 15 (optical fiber having the resin coating 14) exposed to the portion 19 is wired in a state where it can be bent and bent in a U-shape in a space 54 between the substrates 51 and 52. The transmitter 2 and the receiver 3 are mounted on the axis of the optical fiber 10 bent by sliding.
In the optical module 50, for example, in a device in which a first casing and a second casing are connected to each other by a slide portion so as to be movable in parallel, the first substrate 51 of the optical module 50 is installed in the first casing. Then, the second substrate 52 can be installed in the second housing, and the space 54 between the substrates 51 and 52 can be used between the first housing and the second housing.

  The optical module 60 of the fifth embodiment shown in FIG. 6 has two optical fibers 10 and two reciprocally movable along the arrow 63, like the optical module 50 of the fourth embodiment shown in FIG. The board 61, 62, the transmitter 2 mounted on the first board 61, and the receiver 3 mounted on the second board 62 are installed in a space 64 between the boards 61, 62. The receiver 3 is installed on an axis 66 at a position different from the position of the axis 65 of the optical fiber. As described above, the receiver 3 (similarly, the transmitter 2) can be installed at another position away from the sliding axis (distance W). The degree is improved.

  In many devices such as mobile phones, functions such as a camera, a keyboard, and a memory are used on a plurality of modularized boards via a main board. When information transmission between the substrates serving as these branches is performed by optical wiring, an optical module having two or three or more substrates can be used to route the optical fibers along the plurality of substrates. . 3, 4, 5, and 6, the boards 31, 41, 51, 61 on which the transmitter 2 is mounted and the boards 32, 43, 52, 62 on which the receiver 3 is mounted are separate. However, the transmitter 2 and the receiver 3 may be mounted on the same substrate. Further, on the substrate on which neither the transmitter 2 nor the receiver 3 is mounted, the optical fiber 10 may be in a state of being wired, or other like the second substrate 42 shown in FIG. The electronic component 5 may be mounted. In the present invention, the wiring between the substrates is not limited to the optical wiring, and a separate electrical wiring may be provided.

In the optical modules 30 and 40, the substrates 31, 41, 51, and 61 on which the light emitting elements are mounted have circuits (not shown) that are electrically connected to the elements to operate the light emitting elements. The substrates 32, 43, 52, and 62 on which the light receiving element is mounted have a circuit (not shown) electrically connected to the light receiving element in order to operate the light receiving element.
Examples of such a substrate include a printed circuit board in which a circuit is formed by etching a copper foil, printing a conductive paste, or the like.

  Thus, since the end 7 of the optical fiber 10 and the light emitting element of the transmitter 2 are mounted on the same substrate 31, 41, 51, 61, the alignment of the light emitting element with respect to the end 7 of the optical fiber 10 is performed. It becomes easy. Similarly, since the end 8 of the optical fiber 10 and the light receiving element of the receiver 3 are mounted on the same substrate 32, 43, 52, 62, the alignment of the light receiving element with respect to the end 8 of the optical fiber 10 is easy. become.

  Here, the configuration of a metal-coated optical fiber suitable for the present invention will be described in more detail.

Specific examples of an optical fiber having a core diameter (outer diameter of the core 11) in the range of 50 μm or more and 62.5 μm or less include a graded index (GI) optical fiber having a core diameter of 50 μm and a cladding diameter of 125 μm, a core Examples include graded index (GI) optical fibers having a diameter of 62.5 μm and a cladding diameter of 125 μm, and graded index (GI) optical fibers having a core diameter of 50 μm and a cladding diameter of 80 μm.
A multi-mode optical fiber such as a GI optical fiber is preferable because the core diameter is larger than that of the single-mode optical fiber and optical coupling with the light emitting / receiving element is easy.

  The resin coating 14 is preferably made of polyimide from the standpoint of excellent heat resistance and chemical stability and durability against coating treatment for forming a metal coating. In addition, an ultraviolet curable resin, a silicone resin, or the like can be used for the resin coating 14. The resin coating 14 may be only one layer or may be two or more layers. As for the thickness of the resin coating 14, about 5-40 micrometers is mentioned, for example. As a specific example, for example, when the outer diameter (cladding diameter) of the bare optical fiber 13 is 125 μm, the outer diameter (coating diameter) of the optical fiber 15 is 160 μm.

  The first metal coating 16 preferably has a thickness in the range of 0.1 μm to 5 μm. In particular, about 1 μm is preferable. Examples of the metal material constituting the first metal coating 16 include Cu, Ni, Sn, Cr, Zn, a Cu—Zn alloy, and a Cu—Ni alloy.

  An example of a method for forming the first metal coating 16 is electroless plating. Specifically, an electroless copper plating bath chemical solution (trade name: OPC Copper (Okuno Pharmaceutical Co., Ltd.)) to which formalin is added as a reducing agent is used, the chemical temperature is maintained at 30 ° C., and a predetermined film thickness is obtained. The method of performing an electroless plating process is mentioned.

  In addition to the electroless plating, the first metal coating 16 can be formed by vacuum evaporation or sputtering. Furthermore, the first metal coating 16 is formed by combining two or more of these methods. May be. The first metal coating 16 also serves as an underlayer for the second metal coating 17 described later. If the thickness of the first metal coating 16 is too small, the thickness of the second metal coating 17 tends to be uneven, which is not preferable. On the other hand, if the thickness of the first metal coating 16 is too large, it takes a long time to form a film, which is not preferable because the productivity is poor and the manufacturing cost is high.

  When electroless plating is used to form the first metal coating 16, Cu, Ni, and Sn are generally preferred as metals that can be electrolessly plated. When other metal materials are used, other methods such as vacuum deposition and sputtering can be used. When using vacuum deposition or sputtering, it is practically difficult to increase the thickness of the first metal coating 16 as compared with electroless plating. Zn, Cu—Zn alloy, and Cu—Ni alloy are preferable.

  The second metal coating 17 preferably has a thickness in the range of 50 μm or more and 95 μm or less. In particular, about 60 μm is preferable. Examples of the metal material constituting the second metal coating 17 include Cu, Ni, Cr, Zn, Ag, Au, a Cu—Zn alloy, and a Cu—Ni alloy.

One example of a method for forming the second metal coating 17 is electrolytic plating. Specifically, a copper sulfate plating bath chemical solution (mixed in a weight ratio of sulfuric acid 4 to copper sulfate pentahydrate 1 and added to a chemical solution containing 50 ppm of chlorine ions, an additive (trade name: cover cream, manufactured by Meltex) In this chemical solution, a current density of 2.5 A / dm ² is passed through the first metal coating 16 and electrolytic plating is performed until a predetermined thickness is obtained.

  As a chemical solution for electrolytic plating, a copper bromide bath or a copper pyrophosphate bath generally used for electrolytic copper plating can be used in addition to the above-described one. When the second metal coating 17 is formed by electrolytic plating using the first metal coating 16 as a base layer, the thickness of the metal coating can be increased efficiently, and the bending state of the optical fiber 15 can be maintained. It is preferable because the required thickness can be reached in a relatively short time. If the thickness of the second metal coating 17 is too small, the bending state of the optical fiber 15 may not be maintained due to insufficient plastic force, which is not preferable. If the thickness of the second metal coating 17 is too large, the second metal coating 17 becomes too hard, and there is a possibility that the second metal coating 17 may crack when the optical fiber 10 is bent. It is not preferable.

  For the second metal coating 17, a preferable metal can be used as appropriate in consideration of a hue or the like. It is desirable to have the rigidity necessary to hold the optical fiber 15 in a bent state. The metal described above is suitable because of factors such as high rigidity and good color.

  An insulating coating (outer coating) made of an insulating resin can also be formed around the metal coating 18. As the outer cover, it is only necessary that the outer cover is soft enough to prevent plastic deformation of the metal coating 18 and has greenness. Preferred examples of the insulating resin used for the outer jacket include silicone resin and styrene rubber. When the metal coating 18 is composed of two layers of metal coatings 16 and 17, the jacket is provided around the second metal coating 17.

When soldering the metal-coated optical fiber 10 provided with the outer cover, it is necessary to remove the outer cover at least at the place to be soldered.
It is preferable to provide a jacket on the outside of the metal coating 18 because the metal coating 18 can be electrically insulated from the outside. When the optical fiber comes into contact with the circuit on the substrate or when an electric signal is transmitted to the metal coating 18, adverse effects on the operation of the circuit on the substrate and the electric signal transmitted to the metal coating 18 can be suppressed. .

FIG. 10 illustrates a method for measuring the shape retention force of the metal-coated optical fiber. As shown in FIG. 10A, a SUS mandrel M having an outer diameter of 30 mm is used, and the central portion of the optical fiber F having a total length of 1 m is wound around the mandrel M substantially perpendicularly with an unreasonable force. In this state, the mandrel M is removed, and the optical fiber F is left for a predetermined time (for example, 24 hours or 48 hours).
As shown in FIG. 10B, the maximum inner diameter r1 of the ring-shaped portion in a state where the optical fiber F is wound around the mandrel M and the maximum inner diameter r2 after a predetermined time (for example, 24 hours or 48 hours) have passed. Measure and define the strain release rate P according to the following equation (1).

  P = ((r2-r1) ÷ r1) × 100 (%) (1)

  If the strain release rate is 5% or less and there is almost no change between the maximum inner diameter after 24 hours and the maximum inner diameter after 48 hours, it is determined that the shape retention of the metal-coated optical fiber is good. be able to.

The outer diameter of the core 11 is 50 to 62.5 μm, the outer diameter of the cladding 12 is 80 to 125 μm, the thickness of the resin coating 14 is 5 to 40 μm, the thickness of the first metal coating 16 is 0.1 to 5.0 μm, For the metal-coated optical fiber having a thickness of 50 to 95 μm, a sample serving as an example was prepared.
In the sample, a silica-based GI optical fiber having a core outer diameter of 50 μm and a cladding outer diameter of 125 μm is used. The outer diameter of the resin coating made of polyimide is 160 μm, the thickness of the first metal coating made of Cu is 0.1 μm, and Ni A metal-coated optical fiber in which a coating is formed so that the thickness of the second metal coating is 50 μm. The strain release rate after 24 hours of this sample (P2 when r2 is measured after 24 hours) is 2.1%, and the strain release rate remains almost unchanged even after 48 hours, maintaining a good shape. Characteristics were shown.

  The present invention can be used for optical wiring in various devices such as high-speed communication devices such as servers, video information devices such as game machines, and small electronic devices such as mobile phones.

It is a perspective view which shows the 1st example of an optical module of this invention. It is sectional drawing which shows an example of the structure which soldered the metal-coated optical fiber to the board | substrate. It is a perspective view which shows the 2nd example of an optical module of this invention. It is a perspective view which shows the 3rd example of an optical module of this invention. It is a perspective view which shows the 4th example of an optical module of this invention. It is a perspective view which shows the 5th example of an optical module of this invention. It is sectional drawing which shows an example of the structure of a metal-coated optical fiber. It is sectional drawing which shows an example of the space | gap part of a metal-coated optical fiber. It is the schematic which shows an example of the structure which uses the metal coating | coated of a metal-coated optical fiber for electrical signal transmission. It is explanatory drawing which shows an example of the verification method of the shape maintenance characteristic of a metal-coated optical fiber, (a) is sectional drawing which shows the state which wound the metal-coated optical fiber around the mandrel, (b) is a metal-coated optical fiber. It is a top view which shows the state after removing from a mandrel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 31, 32, 41, 42, 43, 51, 52, 61, 62 ... Board | substrate, 2 ... Transmitter (transmitter module incorporating a light emitting element), 3 ... Receiver (receiver module incorporating a light receiving element) 4 ... solder, 6 ... land pattern, 7,8 ... end of optical fiber, 10 ... metal-coated optical fiber (optical fiber), 11 ... core, 12 ... cladding, 13 ... bare optical fiber (quartz-based light) Fiber), 14 ... resin coating, 15 ... optical fiber, 16 ... first metal coating, 17 ... second metal coating, 18 ... metal coating, 19 ... gap, 20, 30, 40, 50, 60 ... Optical module (optical wiring structure).

Claims (12)

One or more light-emitting elements optically coupled with an optical fiber, one or more substrates holding at least a part of the optical fiber, and an optical fiber having an alignment with respect to an end of the optical fiber And / or a light receiving element, and the substrate has a circuit electrically connected to the light emitting element and / or the light receiving element to operate the light emitting element and / or the light receiving element. An optical module mounted on the same substrate as the end of an optical fiber optically coupled to the element,
The optical fiber is a metal-coated optical fiber in which a resin coating is provided on the outer periphery of the clad of the silica-based optical fiber, and a metal coating is provided on the outer periphery of the resin coating to maintain the wiring shape of the optical fiber. Yes, this metal-coated optical fiber has a void portion that is a portion having no metal coating in the middle portion in the longitudinal direction of the optical fiber, and the optical fiber having a resin coating exposed in the void portion is bent. An optical module characterized by being wired in.   The optical module according to claim 1, wherein one end of the optical fiber is optically coupled to a light emitting element, and the other end of the optical fiber is optically coupled to a light receiving element. .   3. The optical module according to claim 1, wherein a length of the gap is in a range of 30 mm or more and 50 mm or less.   The optical module according to any one of claims 1 to 3, wherein the gap is provided at two or more locations per metal-coated optical fiber.   The core diameter of the optical fiber is in the range of 50 μm or more and 62.5 μm or less, and the metal coating is provided on the outer periphery of the first metal coating and the first metal coating provided on the outer periphery of the resin coating. The optical module according to claim 1, wherein the optical module is made of a second metal coating.   The optical module according to claim 5, wherein the thickness of the first metal coating is in a range of 0.1 μm to 5 μm.   7. The optical module according to claim 5, wherein a thickness of the second metal coating is in a range of 50 μm or more and 95 μm or less.   The said 1st metal coating consists of either Cu, Ni, Sn, Cr, Zn, a Cu-Zn alloy, or a Cu-Ni alloy, The said any one of Claims 5-7 characterized by the above-mentioned. Light module.   The said 2nd metal coating consists of either Cu, Ni, Cr, Zn, Ag, Au, Cu-Zn alloy, or Cu-Ni alloy, The any one of Claims 5-8 characterized by the above-mentioned. The optical module as described in.   The optical module according to any one of claims 1 to 9, wherein the metal-coated optical fiber is soldered onto a land pattern of a substrate and wired substantially parallel to the substrate.   Two or more substrates are provided, and the metal-coated optical fiber has the gap at a position where the optical fiber is wired between the substrates, and the relative position between the substrates can change between the substrates. It has a structure, The optical module as described in any one of Claims 1-10 characterized by the above-mentioned.   An apparatus comprising the optical module according to claim 1.

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